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1. (WO2019064022) WIRELESS OPTICAL COMMUNICATION AND IMAGING SYSTEMS AND METHODS
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WIRELESS OPTICAL COMMUNICATION AND IMAGING SYSTEMS AND

METHODS

FIELD

The present disclosure relates to a wireless optical communication system and method for use in manufacturing operations, and in particular, though not exclusively, for controlling multiple apparatus using light. The present disclosure also relates to a system and method for use in photometric stereo-imaging and in particular, though not exclusively, for use in manufacturing operations and/or surveillance operations.

BACKGROUND

Manufacturing operations using multiple apparatus are known. However, coordinating the manufacturing operations performed using different apparatus can be difficult and/or expensive to implement, especially when the different apparatus are manufactured by different manufacturers.

Methods of photometric stereo imaging are known for providing photometric stereo images of still objects. However, such methods are not suitable for imaging moving objects.

SUMMARY

It should be understood that any one or more of the features of any of the following aspects or embodiments may be combined with any one or more of the features of any of the other aspects or embodiments.

According to at least one aspect or to at least one embodiment there is provided a wireless optical communication system for use in manufacturing operations, the system comprising:

an optical transmitter arrangement;

a first optical receiver arrangement for attachment to a first apparatus;

a second optical receiver arrangement for attachment to a second apparatus; and

a controller configured to control the optical transmitter arrangement to transmit a first signal using a first light beam to the first optical receiver arrangement and to transmit a second signal using a second light beam to the second optical receiver arrangement,

wherein the first optical receiver arrangement is configured to detect the first light beam and determine the first signal from the detected first light beam and the second optical receiver arrangement is configured to detect the second light beam and determine the second signal from the detected second light beam, and

wherein the first signal includes one or more commands or instructions for causing the first apparatus to perform a first manufacturing operation and the second signal includes one or more commands or instructions for causing the second apparatus to perform a second manufacturing operation.

The controller may control the optical transmitter arrangement to transmit the first and second signals using the first and second light beams so as to co-ordinate the first and second manufacturing operations. Use of such a system may be particularly advantageous where the first and second apparatus are manufactured by different manufacturers and/or where the first and second apparatus use different command sets, instruction sets and/or computer languages.

The controller may be configured to operate in a controller computer language.

The first apparatus may be configured to operate in a first apparatus computer language. The second apparatus may be configured to operate in a second computer language.

The controller may be configured to control the optical transmitter arrangement to transmit the first signal in the controller computer language using the first light beam to the first optical receiver arrangement. The first optical receiver arrangement may be configured to translate the first signal from the controller computer language to the first apparatus computer language. The controller may be configured to control the optical transmitter arrangement to transmit the second signal in the controller computer language using the second light beam to the second optical receiver arrangement. The second optical receiver arrangement may be configured to translate the second signal from the controller computer language to the second apparatus computer language. Transmitting the first and/or second signals in the controller computer language and translating the first and/or second signals using the first and/or second optical receiver arrangements may avoid any requirement for the user of the system to configure or program the controller to translate between the controller computer language and the each of the first and second apparatus computer languages. This may be particularly advantageous when different apparatus are made by different manufacturers and use different computer languages.

The controller may be configured to translate one or more commands or instructions between the controller computer language and the first apparatus computer language and to control the optical transmitter arrangement to transmit the first signal to the first optical receiver arrangement in the first apparatus computer language using the first light beam. The controller may be configured to translate one or more commands or instructions between the controller computer language and the second apparatus computer language and to control the optical transmitter arrangement to transmit the second signal to the second optical receiver arrangement in the second apparatus computer language using the second light beam.

The first signal may be defined by varying one or more properties of the first light beam in time and/or in space. The first signal may be defined by varying at least one of the amplitude, phase, intensity, power, wavelength, and polarisation of the first light beam in time and/or in space. The first signal may be encoded on the first light beam in time and/or in space.

The second signal may be defined by varying one or more properties of the second light beam in time and/or in space. The second signal may be defined by varying at least one of the amplitude, phase, intensity, power, wavelength, and polarisation of the second light beam in time and/or in space. The second signal may be encoded on the second light beam in time and/or in space.

The optical transmitter arrangement and the first optical receiver arrangement may be separated by a gap such as an air gap so as to define a first optical path therebetween in free space. The optical transmitter arrangement and the second optical receiver arrangement may be separated by a gap such as an air gap so as to define a second optical path therebetween in free space.

The optical transmitter arrangement may be configured to transmit the first and second light beams independently of one another.

The first and second light beams may be spatially distinct. The first and second light beams may be spectrally distinct (e.g. emitted at different wavelengths), temporally distinct (e.g. emitted at different times) and/or modulated at different frequencies. This may avoid the second optical receiver arrangement receiving the first signal, and may avoid the first optical receiver arrangement receiving the second signal.

The system may be configured such that each optical receiver arrangement may only detect the corresponding light beam or receive the corresponding signal.

Each light beam may be detected by only one optical receiver arrangement. Each light beam may be detected by only one optical receiver arrangement at a time.

The first and/or second manufacturing operation may comprise an additive or a subtractive manufacturing process of any kind. The first and/or second manufacturing operation may comprise at least one of: a forming operation, a shaping operation, a processing operation, a heating operation, a cooling operation, a temperature controlled operation, an assembly operation, a joining operation, a cutting operation, a moving operation, a mixing operation, a hazardous operation, a chemical process, and/or a packaging operation.

The manufacturing operation may comprise a light-activated process e.g. a process which is directly initiated by the absorption of light. The light-activated process may be a photochemical process. The light activated process may be a light activated chemical reaction e.g. light activated chemical bond formation. The light activated process may be a light activated chemical decomposition e.g. light activated chemical bond breaking.

The first and second manufacturing operations may be performed on the same sample, object or item. The first and second manufacturing operations may be performed on different samples, objects or items. Each sample, object or item may comprise at least one of a gas, a liquid and a solid.

The first and second manufacturing operations may be simultaneous. The first and second manufacturing operations may be sequential. The first and second manufacturing operations may at least partially overlap. The first and second manufacturing operations may be independent from each other. The first and second manufacturing operations may be performed repeatedly and/or continuously.

The first and second manufacturing operations may be performed on different samples, objects or items at the same time.

The first and second manufacturing operations may be performed on the same sample, object or item at different times.

The first and/or second apparatus may comprise manufacturing equipment. The first and/or second apparatus may comprise a machine tool or the like.

The first and/or second apparatus may be configured to manipulate or move a sample, object or item. For example, the first and/or second apparatus may comprise a robot. The first and/or second apparatus may be moveable. The first and/or second apparatus may comprise moving parts.

One of the first and second apparatus may be configured to move relative to the other of the first and second apparatus. For example, the first apparatus may comprise manufacturing equipment for performing the first manufacturing operation on a sample, object or item and the second apparatus may comprise a robot for moving or manipulating the sample, object or item relative to the first apparatus.

The first and/or second apparatus may be configured to contain and/or hold a sample, object or item. For example, the first and/or second apparatus may be configured to contain and/or hold a sample, object or item in a container, on a stage and/or in a bath.

The sample, object or item may comprise a device. For example, the sample, object or item may comprise at least one of an electronic device, an optoelectronic device and a photonic device. The sample, object or item may comprise an LED such as an organic LED (OLED). The sample, object or item may comprise a photovoltaic device and/or a solar cell, for example an organic solar cell.

The sample, object or item may be processed and/or produced during the manufacturing operations.

The sample, object or item may comprise a light-sensitive chemical composition. The sample, object or item may comprise one or more chemical precursors. The sample, object or item may comprise one or more polymer precursors. The sample, object or item may comprise one or more additives in a polymer.

The first and/or second apparatus may be semi-autonomous. Specifically, the first and second apparatus may be configured to act on their respective instructions, and to act independently of the controller and/or one another after receipt of the first and second signals at the first and second optical receiver arrangements respectively.

The optical transmitter arrangement may comprise one or more optical sources.

The optical transmitter arrangement may comprise one optical source for each optical receiver arrangement. Each optical source may be configured to transmit or emit a different light beam. Each optical source may be configured to transmit or emit a different light beam to a different optical receiver arrangement.

The optical transmitter arrangement may comprise one or more LEDs. The optical transmitter arrangement may comprise a micro-LED array. Each LED may have an active or light emitting area from 5 μηι χ 5 μηι to 10 mm χ 10 mm, for example of the order of 100 μηι χ 100 μηι. Each LED may be a gallium nitride (GaN) LED. Each LED may be a white LED. Each LED may be a red-green-blue-white LED. The LEDs

may transmit or emit white light. The LEDs may all transmit or emit the same spectrum. The LEDs may transmit or emit ultraviolent and/or infrared radiation.

The optical sources may be arranged in any shape. The optical sources may be arranged in a rectangular, square, or other shape. The one or more optical sources may be arranged in an n χ m array. The preferred arrangement of the optical sources will be readily understood by one skilled in the art, based on the nature of the optical sources, the first and second apparatus, the first and second manufacturing operations, and the scene into which the optical transmitter arrangement transmits light.

The one or more optical sources may be configured to operate independently. The one or more optical sources may be configured to transmit or emit light independently of each other. The one or more optical sources may be configured to transmit or emit light in a different direction to the other optical sources. The one or more optical sources may be configured to transmit or emit light which is spatially distinct from the light transmitted or emitted from the other optical sources. The one or more optical sources may be configured to transmit or emit light which does not spatially overlap with the light transmitted or emitted from the other optical sources.

The optical transmitter arrangement may comprise an optical source and at least first and second controllable optical redirection elements, wherein the first controllable optical redirection element is configured to direct or transmit a first portion of the light beam to the first optical receiver arrangement as the first light beam and the second controllable optical redirection element is configured to direct or transmit a second portion of the light beam to the second optical receiver arrangement as the second light beam.

The optical transmitter arrangement may comprise an array of controllable optical redirection elements, wherein the array of controllable optical redirection elements includes the first and second controllable optical redirection elements.

The array of controllable optical redirection elements may comprise a spatial light modulator. The array of controllable optical redirection elements may comprise a micro-mirror array.

The first and/or second light beams may comprise structured light. Structured light may encode or define information using the spatial distribution of the light. The use of first and/or second light beams comprising structured light may allow more information or data to be transmitted using the first and/or second light beams. As will be described below, the use of first and/or second light beams comprising structured

light may allow the position of the first and/or second optical receiver arrangements to be determined and/or tracked.

The optical transmitter arrangement may be configured to transmit structured light. The optical transmitter arrangement may be a structured light projection apparatus. The optical transmitter arrangement may be configured to project, transmit or emit structured light.

The first and/or second light beams may comprise at least one of visible, ultraviolet and infrared light.

The optical transmitter arrangement may be configured to transmit visible light. The optical transmitter arrangement may be configured to transmit ultraviolet and/or infrared light.

The optical transmitter arrangement may be configured to illuminate a scene in which the first and second apparatus are located. The optical transmitter arrangement may be configured to illuminate the scene in a flicker-free manner. A flicker-free manner may be one in which the flickering, modulation and/or frequency of the light illuminating the room is too fast for the human eye to perceive i.e. the human eye perceives a constant average illumination. The scene may comprise at least part of an enclosed area or space such as a room or part of a room. The optical transmitter arrangement may be a room light e.g. a source of light to at least partially illuminate at least part of an enclosed area or space. The optical transmitter arrangement may be configured to illuminate, in a flicker-free manner, a scene which includes the first and second apparatus whilst also transmitting the first signal using the first light beam to the first optical receiver arrangement and transmitting the second signal using the second light beam to the second optical receiver arrangement.

The optical transmitter arrangement may be configured for covert optical communications with the first and second optical receiver arrangements. The first and second light beams transmitted by the optical transmitter arrangement may be difficult to distinguish from light generated by other light sources or room lights in the scene. The optical transmitter arrangement may be difficult to distinguish from a room light.

The optical transmitter arrangement may comprise one or more optical elements. Each optical element may be configured to alter light emitted from one or more optical sources of the optical transmitter arrangement. Each optical element may comprise a filter, a lens, a mirror and/or a waveplate.

The first and/or second optical receiver arrangement may comprise a point detector. The first and/or second optical receiver arrangement may comprise at least

one of a photodiode such as an avalanche photodiode (APD), a photomultiplier tube (PMT), and a photoconductor. The first and/or second optical receiver arrangement may comprise an area detector or an image sensor e.g. a CCD image sensor or a CMOS image sensor. The first and second optical receiver arrangements may be the same, or they may be different.

The first apparatus and/or the second apparatus may comprise one or more sensors. The one or more sensors may comprise one or more of a temperature sensor, a pressure sensor, a position sensor, an accelerometer, a range finder, an image sensor, a camera such as a video camera, and a machine vision system. One skilled in the art will understand that other sensors may be used and that the type of sensor required will be readily apparent based on the nature of the first and second apparatus, and/or the first and second manufacturing operations.

The system may comprise a first apparatus optical transmitter arrangement for attachment to the first apparatus. The first apparatus optical transmitter arrangement may be provided with, or located or mounted adjacent to, the first optical receiver arrangement.

The system may comprise a second apparatus optical transmitter arrangement for attachment to the second apparatus. The second apparatus optical transmitter arrangement may be provided with, or located or mounted adjacent to, the second optical receiver arrangement.

The system may comprise a system optical receiver arrangement. The system optical receiver arrangement may be provided with, or located or mounted adjacent to, the controller. The system optical receiver arrangement may be configured for communication with the controller. The system optical receiver arrangement may comprise a plurality of optical detectors. Each optical detector may correspond to a different apparatus.

The first apparatus optical transmitter arrangement may be configured to transmit a first return signal from the first apparatus optical transmitter arrangement to the system optical receiver arrangement using a first return optical beam. In effect, this may allow for two-way communication between the controller and the first apparatus.

The second apparatus optical transmitter arrangement may be configured to transmit a second return signal from the second apparatus optical transmitter arrangement to the system optical receiver arrangement using a second return optical beam. In effect, this may allow for two-way communication between the controller and the second apparatus.

The first and/or second apparatus optical transmitter arrangement may be a structured light projector, transmitter or emitter. The first and/or second apparatus optical transmitter arrangement may be configured to communicate a corresponding return signal using structured light. The first and/or second apparatus optical transmitter arrangement may be configured to transmit data at high speeds, for example to transmit data at speeds of the order of Mb/s.

The system optical receiver arrangement may be comprise an area detector, such as an image sensor. The system optical receiver arrangement may be configured to receive a return signal transmitted from the first and/or second apparatus optical transmitter arrangements using structured light.

The use of such first and/or second apparatus optical transmitter arrangements and such a system optical receiver arrangement may allow large quantities of data to be communicated from the first and/or second apparatus to the controller at high data transfer speeds. For example, the one or more sensors of the first and/or second apparatus may generate large quantities of data, and it may be advantageous to communicate data measured by the one or more sensors in real-time to the controller. The controller may use the data received from the first and/or second apparatus to monitor, control and/or modify the first and/or second manufacturing operations.

Each of the first and/or second apparatus optical transmitter arrangements may comprise any of features of the optical transmitter arrangement. The system optical receiver arrangement may comprise any of the features of the first and/or second optical receiver arrangements.

Such a system may not only use light to provide commands or instructions to the first and second apparatus to co-ordinate the first and second manufacturing operations, but may also use light to perform one or both of the first and second manufacturing operations, to sense or image a sample, object or item before, during and/or after one or both of the first and second manufacturing operations and/or to send sensed data such as image data back to the controller so that the controller may determine or know a property of the sample, object or item before, during and/or after the first and second manufacturing operations.

The system may comprise one or more further optical receiver arrangements. Each of the further optical receiver arrangements may be configured for attachment to the first and/or second apparatus. The optical transmitter arrangement may be configured to transmit a corresponding signal using a corresponding light beam to each of the further optical receiver arrangements. Any of the further optical receiver arrangements may comprise any of the features of the first and/or second optical receiver arrangements.

Each of the further optical receiver arrangements may be configured for attachment to a corresponding further apparatus.

Some of the optical receiver arrangements may be configured for attachment to the same apparatus, for example to the first or second apparatus or to a further apparatus. Any of the further apparatus may comprise any of the features of any of the first and/or second apparatus.

At least one of the first signal, the second signal, the first return path signal and the second return path signal may comprise data.

The first optical receiver arrangement may be configured to decode the first signal. The first optical receiver arrangement may be configured to communicate the first signal to the first apparatus.

The second optical receiver arrangement may be configured to decode the second signal. The second optical receiver arrangement may be configured to communicate the second signal to the second apparatus.

The controller and the optical transmitter arrangement may be configured for communication, for example wired or wireless communication, with one another. The controller and the optical transmitter arrangement may be configured for electrical and/or optical communication with one another. The controller and the optical transmitter arrangement may be unitary, may be located adjacent to one another, or may be located remotely from one another.

The controller may be configured to control the temporal variation and/or spatial distribution of light transmitted by the optical transmitter arrangement. The controller may be configured to control the one or more optical sources. The controller may be configured to control which optical sources are on and which are off. The controller may be configured to control any property of the light transmitted or emitted from each optical source.

The controller may comprise a computer. The controller may comprise a user interface.

The system may be off-grid. The system may comprise a renewable energy source, such as a wind turbine or solar cell. The system may comprise a battery. The renewable energy source may charge the battery. The system may be powered by the renewable energy source and/or the battery. The optical transmitter arrangement may be low power. For example, the optical transmitter arrangement may transmit or emit

light with a power of the order of a mW or less. The optical transmitter arrangement may be configured to transmit or emit the first and second light beams with a low intensity and/or a low power. This may advantageously allow the system to be low power. The system may have sufficiently low power requirements to be off-grid and powered by renewable energy sources e.g. a solar panel.

The system may be configured for photometric stereo-imaging. For example, the system may be configured for photometric stereo-imaging of a scene. The scene may include one or more samples, objects or items.

The system may comprise a camera.

The camera may be configured for communication, for example wired or wireless communication, with the controller. The controller may be configured to analyse images recorded by the camera.

The system may comprise a single camera.

The optical transmitter arrangement may comprise 2, 3, 4, or more, optical sources. The optical transmitter arrangement may comprise 10 or fewer optical sources.

The optical sources may be spatially distinct. Each of the optical sources may be configured to transmit or emit light in different directions and/or at different angles from the other optical sources. Each optical source may be separated from each of the other optical sources by a distance which is comparable to, or which constitutes a significant proportion of, the distance from the optical source to a sample, object or item in the scene. Each optical source may be separated from each of the other optical sources by a distance which is at least 10%, at least 50%, or at least 90% of the distance from the optical source to the sample, object or item in the scene to be imaged. One skilled in the art will understand how to arrange the optical sources relative to one another and/or to the camera to achieve photometric stereo-imaging.

The optical sources may be arranged in a plane. The optical sources may be arranged in a pattern or array, such as a regular pattern or a regular array. The optical sources may be arranged in a rectangle or a square. The optical sources may be arranged in a symmetric configuration.

The spatial arrangement of the optical sources may be fixed. The spatial arrangement of the optical sources may be known. The spatial arrangement of the optical sources may be known by the controller.

The camera may comprise a video camera.

The video camera may have a frame rate sufficiently high to capture video images.

The video may be flicker-free i.e. the video may have a frame rate sufficiently high such that movement in the video is perceived to be smooth and/or fluid by the human eye. The video may have a frame rate of 15 Hz or more. The video may have a frame rate of 60 Hz or more. The video may have a frame rate of 100 Hz or more, or a frame rate of 1 kHz or more.

The optical sources may be synchronised with the camera.

The controller may be configured to create a photometric stereo video from images recorded by the video camera.

According to at least one aspect or to at least one embodiment there is provided a wireless optical communication method for use in manufacturing operations, the method comprising:

transmitting a first signal using a first light beam from a controller to a first apparatus, detecting the first light beam at the first apparatus and determining the first signal from the detected first light beam; and

transmitting a second signal using a second light beam from a controller to a second apparatus, detecting the second light beam at the second apparatus, and determining the second signal from the detected second light beam,

wherein the first signal includes one or more commands or instructions for causing the first apparatus to perform a first manufacturing operation and the second signal includes one or more commands or instructions for causing the second apparatus to perform a second manufacturing operation. The method may be performed using the system described above.

The first signal may be defined by varying one or more properties of the first light beam in time and/or in space. The first signal may be defined by varying at least one of the intensity, the power, the wavelength, and the polarisation of the first light beam in time and/or in space.

The second signal may be defined by varying one or more properties of the second light beam in time and/or in space. The second signal may be defined by varying at least one of the intensity, the power, the wavelength, and the polarisation of the second light beam in time and/or in space.

The first signal may be transmitted using a spatial intensity distribution of the first light beam, for example a time-varying spatial intensity distribution of the first light beam. The first signal may be transmitted by varying the intensity of the first light beam in time. The variation in the intensity of the first light beam may be small. The variation in the intensity of the first light beam may be undetectable by the human eye e.g. the first light beam may change faster than the human eye can detect.

The second signal may be transmitted using the second light beam in any of the same ways as the first signal may be transmitted using the first light beam as described above.

The method may comprise exclusively transmitting the first signal from the controller to the first apparatus using the first light beam. The method may comprise exclusively transmitting the second signal from the controller to the apparatus using the second light beam. Transmitting the first and second signals exclusively from the controller to the first and second apparatus respectively using the first and second light beams may avoid any requirement to use a handshake protocol which would otherwise be required when broadcasting information such as commands, instructions or data to both the first and second optical receiver arrangements. Transmitting the first and second signals exclusively from the controller to the first and second apparatus respectively may allow different information such as different commands, instructions or data to be transmitted from the controller as the first and second signals to the first and second apparatus, for example using different command sets, different instruction sets or different computer languages. This may be advantageous where the first and second apparatus use different command sets, different instruction sets or different computer languages, for example because the first and second apparatus are manufactured by different manufacturers.

The method may comprise:

translating the first signal into a computer language used or understood by the first apparatus; and

translating the second signal into a computer language used or understood by the second apparatus.

The method may comprise using an optical transmitter arrangement to transmit the first signal using the first light beam and the second signal using the second light beam.

The method may comprise using the optical transmitter arrangement to transmit the first signal using the first light beam to a first optical receiver arrangement provided with the first apparatus. The method may comprise using the optical transmitter

arrangement to transmit the second signal using the second light beam to a second optical receiver arrangement provided with the second apparatus.

The method may comprise using a controller to control the optical transmitter arrangement.

The controller may use or understand a controller computer language. The first apparatus may use or understand a first apparatus computer language. The second apparatus may use or understand a second apparatus computer language.

The method may comprise transmitting the first signal in the controller computer language using the first light beam. The method may comprise using the first optical receiver arrangement to translate the first signal from the controller computer language into the first apparatus computer language.

The method may comprise transmitting the second signal in the controller computer language using the second light beam. The method may comprise using the second optical receiver arrangement to translate the second signal from the controller computer language into the second apparatus computer language.

Translating from the controller computer language into the first and/or second apparatus computer language using the first and/or second optical receiver arrangement may advantageously allow easier implementation of the method. For example, if a standard communication language or protocol were established, the controller, optical transmitter arrangement and the first and second signals could all use the standard communication language or protocol. The first and second optical receiver arrangements may be configured to understand the first and second signals transmitted in the standard communication language or protocol and to translate the first and second signals into the first and second apparatus computer languages. This would avoid any requirement for the user of the system to have to program the controller to translate one or more commands or instructions in the controller computer language into the first and/or second apparatus computer languages. One or more further apparatus could be used without any requirement for the user of the system to program the controller to translate between the controller computer language and the one or more computer languages used by the one or more further apparatus. This would be particularly advantageous when using different apparatus from different manufacturers and/or where each apparatus has a different computer language. The method may be cheaper to implement, as a simple controller and optical transmitter arrangement could be used which could communicate with apparatus from any manufacturer.

The method may comprise translating from the controller computer language to the first and/or second apparatus computer language using the controller. The method may comprise transmitting the first signal in the first apparatus computer language using the first light beam from the optical transmitter arrangement to the first optical receiver arrangement. The method may comprise transmitting the second signal in the second apparatus computer language using the second light beam from the optical transmitter arrangement to the second optical receiver arrangement. This may allow all the translation from the controller computer language to the first and/or second apparatus computer language to be performed centrally using the controller.

The method may comprise using one or more sensors associated with the first apparatus to measure first apparatus data. The method may comprise using the first apparatus data to monitor and/or control the first manufacturing operation.

The method may comprise transmitting the first apparatus data from the first apparatus to the controller. For example, the method may comprise transmitting the first apparatus data using a first return optical beam, detecting the first return optical beam, determining the first apparatus data from the detected first return optical beam and providing the determined first apparatus data to the controller.

The method may comprise using one or more sensors associated with the second apparatus to measure second apparatus data. The method may comprise using the second apparatus data to monitor and/or control the second manufacturing operation.

The method may comprise transmitting the second apparatus data from the second apparatus to the controller. For example, the method may comprise transmitting the second apparatus data using a second return optical beam, detecting the second return optical beam, determining the second apparatus data from the detected second return optical beam and providing the determined second apparatus data to the controller.

The method may comprise performing a calibration step. For example, the method may comprise communicating from the first apparatus to the controller one or more commands or instructions the first apparatus is capable of executing and/or the manufacturing operations the first apparatus is capable of performing. The method may comprise communicating from the first apparatus to the controller the one or more commands or instructions the first apparatus is capable of executing and/or the manufacturing operations the first apparatus is capable of performing to the controller via the first apparatus optical transmitter arrangement and the system optical receiver arrangement.

Similarly, the method may comprise communicating from the second apparatus to the controller one or more commands or instructions the second apparatus is capable of executing and/or the manufacturing operations the second apparatus is capable of performing. The method may comprise communicating from the first apparatus to the controller the one or more commands or instructions the second apparatus is capable of executing and/or the manufacturing operations the second apparatus is capable of performing to the controller via the second apparatus optical transmitter arrangement and the system optical receiver arrangement.

The controller may then know the high level commands or instructions each of the first and second apparatus can execute and/or the manufacturing operations each of the first and second apparatus can perform. The controller may co-ordinate the first and second manufacturing operations without the first and second apparatus having to communicate which each other.

The method may comprise communicating from one or more further apparatus to the controller one or more commands or instructions the one or more further apparatus is/are capable of executing and/or the manufacturing operations the one or more further apparatus is/are capable of performing.

The method may comprise transmitting position information to a plurality of positions in a scene which includes the first and second apparatus. The method may comprise transmitting the position information as a series of light patterns. The method may comprise transmitting the series of light patterns into the scene so that each position in the scene receives a unique time-varying optical signal. The method may comprise transmitting the series of light patterns into the scene so that the first and/or second apparatus receives a unique time-varying optical signal. The method may comprise using the optical transmitter arrangement to transmit the series of light patterns.

The method may comprise determining a position associated with the first apparatus from the time-varying optical signal detected at the first apparatus. The method may comprise determining the position of the first optical receiver arrangement from a time-varying optical signal detected by the first optical receiver arrangement.

The method may comprise determining a position associated with the second apparatus from the time-varying optical signal detected at the second apparatus. The method may comprise determining the position of the second optical receiver

arrangement from a time-varying optical signal detected by the second optical receiver arrangement.

The series of light patterns may be selected so that each position in the scene receives a unique time-varying optical signal.

The series of light patterns may comprise opposing or orthogonal light patterns.

Each light pattern in the series of light patterns may be the inverse pattern of the preceding pattern or of the next pattern.

The series of light patterns may comprise pairs of complementary or inverse light patterns. Each pair of complementary light patterns may have an average illumination which is the same. The pairs of complementary light patterns may be determined according to a Manchester encoding method or may be used to implement a Manchester encoding method. Using pairs of complementary light patterns may allow use of the same duty cycle for each optical source.

The series of light patterns may comprise a Hadamard sequence or series of light patterns. The series of light patterns may comprise a subset of a Hadamard sequence or series of light patterns. The use of a Hadamard sequence or a subset of a Hadamard sequence may provide greater average illumination than raster-scanning the scene, one position at a time.

The Hadamard sequence or subset of a Hadamard sequence may comprise stripe patterns.

The Hadamard sequence or subset of a Hadamard sequence may be transmitted at a frame rate above 1 kHz. No visual flicker may be detected by the human eye above a frame rate of 1 kHz. The Hadamard sequence or subset of a Hadamard sequence may be transmitted at a frame rate of 2 kHz.

The method may comprise k patterns in the pattern sequence, where

/c = 2 1og2(iV)

and N is the number of optical sources.

The method may comprise using a series of light patterns which comprises a starting light pattern in which all the optical sources are on. The method may comprise using a series of light patterns which comprises a finishing light pattern in which all the optical sources are off. Using such starting and finishing light patterns may allow an optical receiver arrangement, such as the first or second optical receiver arrangement, located at any position in the scene to know when transmission of the series of light patterns begins and ends. In effect, such starting and finishing light patterns may constitute an embedded clock in the time-varying optical signal received at each

position in the scene. The method may comprise detecting a starting pattern by detecting a maximum light intensity. The method may comprise detecting an end pattern by detecting a minimum light intensity. The method may comprise synchronising the detection of the series of light patterns by detecting the starting pattern and the end pattern.

The first and/or second signal may comprise on/off keying. The first and/or second signal may comprise pulse width modulation (PWM), pulse position modulation (PPM) or pulse amplitude modulation (PAM). The first and/or second signal may comprise a data signal having a data rate of 100 kb/s - 1 Mb/s, or 1 Mb/s or more.

The method may comprise illuminating a scene in which the first and second apparatus are located. The scene may comprise an enclosed area or space such as a room or part of a room. The method may comprise illuminating an enclosed area or space whilst transmitting the first and/or second signal.

The method may comprise using an optical transmitter arrangement to transmit the first and second signals using the first and second light beams and using the same optical transmitter arrangement to illuminate the scene in which the first and second apparatus are located.

The method may comprise generating a photometric stereo-image. For example, the method may comprise:

illuminating a scene from a plurality of different directions;

recording an image of at least part of the scene illuminated from each different direction; and

analysing the recorded images to create a photometric stereo-image of at least part of the scene.

The scene may include at least one sample, object and/or item upon which the first and/or second manufacturing operations are performed.

The method may comprise using a camera or an image sensor to record the image of at least part of the scene illuminated from each different direction.

The method may comprise using a plurality of optical sources to illuminate the scene from the different directions.

The method may comprise using a plurality of LEDs such as a plurality of visible or white LEDs to illuminate the scene from the different directions.

The method may comprise using the optical transmitter arrangement to illuminate the scene from the different directions.

The method may comprise using different optical sources of the optical transmitter arrangement to illuminate the scene from the different directions.

The method may comprise illuminating the scene from each of the different directions sequentially. The method may comprise recording one image for each illumination direction, to create a set of images. The method may comprise analysing the set of images to create a photometric stereo-imaging image of at least part of the scene. The method may comprise synchronising the illumination of the scene from the plurality of different directions with the camera, such that the direction of illumination corresponding to each image recorded by the camera can be known.

The method may comprise illuminating the scene from each of the different directions simultaneously. The method may comprise modulating the light used to illuminate the scene from each direction differently. The method may comprise orthogonally modulating the light used to illuminate the scene from different directions. The method may comprise modulating the intensity of the light used to illuminate the scene from different directions with different frequencies. The method may comprise using frequency-division multiple access (FDMA) to modulate the intensity of the light used to illuminate the scene from different directions. The method may comprise recording a series of images of at least part of the scene illuminated simultaneously using the modulated intensity light from each of the different directions. The method may comprise performing a Fourier analysis on the recorded series of images to determine an image of at least part of the scene corresponding to illumination of the scene from each different direction. The method may comprise analysing each of the images of at least part of the scene corresponding to illumination of the scene from each individual direction to create a photometric stereo-imaging image of at least part of the scene.

Using FDMA as described above does not require the different optical sources used to illuminate the scene from different directions to be synchronised with the camera, as the illumination from each direction is determined by performing the Fourier transform. This may also allow for use of a higher duty cycle of the optical sources, as the scene is illuminated from different directions simultaneously, and so the optical sources are transmitting light simultaneously instead of sequentially. This may allow for higher average illumination levels.

The method may comprise generating a series of photometric stereo-images. The method may comprise generating a photometric stereo video of at least part of a scene such as a moving or changing scene. For example, the scene may include at

least one of: a changing or moving sample; a changing or moving object; and/or a changing or moving item.

The method may comprise:

repeatedly recording images of at least part of the scene illuminated from each different direction at a video frame rate; and

analysing the recorded images to create a photometric stereo video image of at least part of the scene.

Each frequency may be real-valued. Each frequency may be less than or equal to the video frame rate.

The method may comprise modulating the intensity of the light used to illuminate the scene from the different directions with different frequencies, wherein each frequency is binary-valued and Manchester encoded. The method may comprise recording a series of images of at least part of the scene when illuminated simultaneously using the modulated intensity light from each of the different directions so as to oversample the modulated intensity light from each of the different directions. The method may comprise multiplying a received signal associated with the recorded series of images by a pre-determined decoding matrix to determine an image of at least part of the scene corresponding to illumination of the scene from each different direction.

The method may comprise:

repeatedly recording images of at least part of the scene illuminated from each different direction at a video frame rate; and

analysing the recorded images to create a photometric stereo video image of at least part of the scene.

Each frequency may be less than or equal to the video frame rate.

The method may comprise using a Manchester-encoded binary FDMA (MEB-FDMA) method to modulate the intensity of the light used to illuminate the scene from the different directions. In MEB-FDMA, each emitter may be modulated with on-off keying at a bit rate equal to or less than the video frame rate, and the FDMA frequencies may be oversampled at this bitrate. Furthermore, each bit may be Manchester-encoded. This approach may enable flicker-free operation and remove the need for synchronisation between the illumination sources and a video camera used to record the images. This approach may enable visible light positioning and photometric stereo-imaging at the same time using the same illumination. The received signal may be decoded via matrix-multiplication with a decoding matrix that can be determined upon system manufacture or installation. The decoding matrix for each emitter may be constructed from the emitter modulation as follows. Let s,, e [-1 1] be the modulation of the ith emitter, where the index j denotes the timeslot. An nxn matrix S(l) may be constructed according to:

c( _

si,l+(j-l+k)%n

where % is the modulo operator. The decoding matrix D(l) for the ith emitter may then obtained by stabilised Gram-Schmidt orthogonalisation of the matrix S(l). The received signal strength of the ith emitter may be retrieved by matrix-multiplication of D(l) with the received signal.

The method may comprise using a video camera to repeatedly record the images of at least part of the scene illuminated from each different direction at a video frame rate.

The method may comprise modulating the intensity of the light from each direction at a different frequency, wherein each frequency is chosen such that the video camera can detect the variation in the intensity of light from each direction. The method may comprise modulating the intensity of the light from each direction at a different frequency, wherein each frequency is less than the frame rate of the video camera. The method may comprise modulating the intensity of the light from each direction at a different frequency, wherein each frequency is less than half the frame rate frequency of the video camera. For example, if the video camera has a frame rate of 60 Hz, the method may comprise modulating the intensity of the light from each direction at a different frequency in the range of 1 to 30 Hz.

The method may comprise transmitting a time-varying data signal using the light illuminating the scene from at least one of the different directions. The method may comprise superimposing the time-varying data signal on the light illuminating the scene from at least one of the different directions. Where the light illuminating the scene from each different direction is modulated at a different frequency, the method may comprise superimposing the time-varying data signal on the modulated light. For example, the method may comprise superimposing the time-varying data signal on the modulated light using at least one of ASK modulation, FSK modulation, PSK modulation, ON/OFF keying, Pulse Amplitude Modulation (PAM), Pulse Width Modulation (PWM) and Pulse Position Modulation (PPM). The method may comprise superimposing the time-varying data signal on the modulated light at a data rate which

is greater than the frequency of modulation of the modulated light. The method may comprise superimposing the time-varying data signal on the modulated light at a data rate of 100 kb/s to 1 Mb/s, 1 Mb/s - 10 Mb/s or 10 Mb/s - 100 Mb/s. The method may comprise superimposing the time-varying data signal on the modulated light at a data rate of 100 kb/s to 1 Mb/s, 1 Mb/s - 10 Mb/s or 10 Mb/s - 100 Mb/s using ON/OFF keying. One skilled in the art will understand that the method may comprise superimposing the time-varying data signal on the modulated light at data rates of up to Gb/s or more with more complex encoding schemes, and that the data rate achievable will vary with the encoding method used.

The method may comprise transmitting data using the light illuminating the scene from more than one direction. The method may comprise transmitting the same data from different directions, or different data from different directions. The method may comprise transmitting data from different directions at different frequencies. The method may comprise separating the data transmitted from different directions by frequency. The method may comprise separating the data transmitted from different directions by performing a Fourier transform on the detected signal.

According to at least one aspect or to at least one embodiment there is provided a computer program or computer program product which, when executed on a processor, causes the processor to implement a wireless optical communication method for use in manufacturing operations, the method comprising:

transmitting a first signal using a first light beam from a controller to a first apparatus, detecting the first light beam at the first apparatus and determining the first signal from the detected first light beam; and

transmitting a second signal using a second light beam from a controller to a second apparatus, detecting the second light beam at the second apparatus, and determining the second signal from the detected second light beam,

wherein the first signal includes one or more commands or instructions for causing the first apparatus to perform a first manufacturing operation and the second signal includes one or more commands or instructions for causing the second apparatus to perform a second manufacturing operation.

The computer program or computer program product may be provided on a carrier medium. The carrier medium may be tangible and/or non-transient.

According to at least one aspect or to at least one embodiment there is provided a system for use in photometric stereo-imaging, the system comprising:

a plurality of optical sources arranged so as to illuminate a scene from a plurality of different directions;

a video camera for repeatedly recording images of at least part of the scene illuminated from each different direction at a video frame rate; and

a controller for analysing the recorded images to create a photometric stereo video of at least part of the scene.

The scene may include one or more samples, objects and/or items.

The video camera may be configured for communication, for example wired or wireless communication, with the controller.

The video camera may have a frame rate sufficiently high to capture video images.

The video may be flicker-free i.e. the video may have a frame rate which is sufficiently high such that movement in the video is perceived to be smooth and/or fluid by the human eye. The video may have a frame rate of 15 Hz or more. The video may have a frame rate of 60 Hz or more. The video may have a frame rate of 100 Hz or more, or a frame rate of 1 kHz or more. The system may comprise a single video camera. This may advantageously allow for a simple photometric stereo imaging system.

The system may comprise 2, 3, 4, or more, optical sources. The system may comprise 10 or fewer optical sources. One, some, or all of the optical sources may be configured to illuminate the scene. The scene may be an enclosed space or area such as a room. One, some, or all of the optical sources may be operable as room lights. The one or more of the optical sources may be configured to illuminate the scene in a flicker-free manner. A flicker-free manner may be one in which the flickering, modulation and/or frequency of the light illuminating the room is too fast for the human eye to perceive i.e. the human eye perceives a constant average illumination. The one or more of the optical sources may be configured to illuminate, in a flicker-free manner, the scene whilst also illuminating the scene from the plurality of different directions.

The optical sources may be spatially distinct. Each of the optical sources may be configured to transmit or emit light in different directions and/or at different angles from the other optical sources. Each optical source may be separated from each of the other optical sources by a distance which is comparable to, or which constitutes a significant proportion of, the distance from the optical source to a sample, object or item in the scene. Each optical source may be separated from each of the other optical sources by a distance which is at least 10%, at least 50%, or at least 90% of the distance from the optical source to the sample, object or item in the scene. One skilled in the art will understand how to arrange the optical sources relative to one another and/or to the camera to achieve photometric stereo-imaging.

The optical sources may be arranged in a plane. The optical sources may be arranged in a pattern or array, such as a regular pattern or a regular array. The optical sources may be arranged in a rectangle or a square. The optical sources may be arranged in a symmetric configuration.

The spatial arrangement of the optical sources may be fixed. The spatial arrangement of the optical sources may be known. The spatial arrangement of the optical sources may be known by the processor.

One or more of the optical sources may comprise an LED or a laser. The plurality of optical sources may comprise a plurality of LEDs such as a plurality of visible or white LEDs. The plurality of optical sources may be configured to emit or transmit structured light.

The optical sources may be synchronised with the video camera.

The system may comprise a receiver. The receiver may comprise an optical receiver arrangement. The optical receiver arrangement may comprise a optical point detector such as photodiode. The optical receiver arrangement may comprise an image sensor such as a CCD sensor or a CMOS sensor.

The system may be configured such that the receiver is in the field of view of the video camera and/or in the scene. The receiver may be moveable in the field of view of the video camera and/or in the scene.

The receiver may be attached to or provided with a robot, an agent and/or a semi-autonomous device. The agent may be a security officer. The receiver may be configured to receive data from the controller.

The receiver may be configured to receive data from the controller via one or more of the optical sources.

The system may comprise a transmitter. The transmitter may be configured for communication with the controller. The receiver may be configured to receive data from the controller via the transmitter.

The receiver may be configured to instruct the robot or semi-autonomous device according to the received data.

This may advantageously allow a robot, agent, or semi-autonomous device to be instructed to investigate and/or correct abnormalities detected by the controller in the photometric stereo video. For example, if the system is used as a security system, a robot or security guard can be informed of the location of a security risk and instructed to investigate further.

The system for use in generating a photometric stereo video may be configured for monitoring one or more manufacturing operations. The receiver may be configured to instruct the robot or semi-autonomous device to investigate and/or fix problems in the manufacturing operation.

According to at least one aspect or to at least one embodiment there is provided a method for use in photometric stereo-imaging, the method comprising: illuminating a scene from a plurality of different directions;

repeatedly recording images of at least part of the scene illuminated from each different direction at a video frame rate; and

analysing the recorded images to create a photometric stereo video of at least part of the scene.

The scene may include one or more samples, objects, and/or items.

The method may comprise using a video camera to repeatedly record the images of at least part of the scene illuminated from each different direction.

The method may comprise illuminating the scene from each of the different directions sequentially. The method may comprise recording one image for each illumination direction, to create a set of images. The method may comprise analysing the set of images to create a photometric stereo video of at least part of the scene. The method may comprise synchronising the illumination of the scene from the plurality of different directions with the video camera, such that the direction of illumination corresponding to each image recorded by the video camera can be known.

The method may comprise illuminating the scene from each of the different directions simultaneously. The method may comprise modulating the light used to illuminate the scene from each direction differently. The method may comprise orthogonally modulating the light used to illuminate the scene from different directions. The method may comprise modulating the intensity of the light used to illuminate the scene from different directions with different frequencies. The method may comprise using frequency-division multiple access (FDMA) to modulate the intensity of the light used to illuminate the scene from different directions. The method may comprise

recording a series of images of at least part of the scene illuminated simultaneously using the modulated intensity light from each of the different directions. The method may comprise performing a Fourier analysis on the recorded series of images to determine an image of at least part of the scene corresponding to illumination of the scene from each different direction. The method may comprise analysing each of the images of at least part of the scene corresponding to illumination of the scene from each different direction to create a photometric stereo-imaging image of at least part of the scene.

Using FDMA as described above does not require the different optical sources used to illuminate the scene from different directions to be synchronised with the camera, as the illumination from each direction is determined by performing the Fourier transform. This may also allow for use of a higher duty cycle of the optical sources, as the scene is illuminated from different direction simultaneously, and so the optical sources are transmitting light simultaneously instead of sequentially. This may allow for higher average illumination levels.

The method may comprise modulating the intensity of the light from each direction at a different frequency, wherein each frequency is chosen such that the video camera can detect the variation in the intensity of light from each direction. The method may comprise modulating the intensity of the light from each direction at a different frequency, wherein each frequency is less than the frame rate of the video camera. The method may comprise modulating the intensity of the light from each direction at a different frequency, wherein each frequency is less than half the frame rate frequency of the video camera. For example, if the video camera has a frame rate of 60 Hz, the method may comprise modulating the intensity of the light from each direction at a different frequency in the range of 1 to 30 Hz.

Each frequency may be real-valued.

The method may comprise modulating the intensity of the light used to illuminate the scene from the different directions with different frequencies, wherein each frequency is binary-valued and Manchester encoded. The method may comprise recording a series of images of at least part of the scene when illuminated simultaneously using the modulated intensity light from each of the different directions so as to oversample the modulated intensity light from each of the different directions. The method may comprise multiplying a received signal associated with the recorded series of images by a pre-determined decoding matrix to determine an image of at

least part of the scene corresponding to illumination of the scene from each different direction.

Each frequency may be less than or equal to the video frame rate.

The method may comprise using a Manchester-encoded binary FDMA (MEB-FDMA) method to modulate the intensity of the light used to illuminate the scene from the different directions. In MEB-FDMA, each emitter may be modulated with on-off keying at a bit rate equal to or less than the video frame rate, and the FDMA frequencies may be oversampled at this bitrate. Furthermore, each bit may be Manchester-encoded. This approach may enable flicker-free operation and remove the need for synchronisation between the illumination sources and a video camera used to record the images. This approach may enable visible light positioning and photometric stereo-imaging at the same time using the same illumination. The received signal may be decoded via matrix-multiplication with a decoding matrix that can be determined upon system manufacture or installation. The decoding matrix for each emitter may be constructed from the emitter modulation as follows. Let s,, e [-1 1] be the modulation of the ith emitter, where the index j denotes the timeslot. An nxn matrix S(l) may be constructed according to:

si,l+(j-l+k)%n

where % is the modulo operator. The decoding matrix D(l) for the ith emitter may then obtained by stabilised Gram-Schmidt orthogonalisation of the matrix S(l). The received signal strength of the ith emitter may be retrieved by matrix-multiplication of D(l) with the received signal.

The method may comprise transmitting a time-varying data signal using the light illuminating the scene from at least one of the different directions. The method may comprise superimposing the time-varying data signal on the light illuminating the scene from at least one of the different directions. Where the light illuminating the scene from each different direction is modulated at a different frequency, the method may comprise superimposing the time-varying data signal on the modulated light. For example, the method may comprise superimposing the time-varying data signal on the modulated light using at least one of ASK modulation, FSK modulation, PSK modulation, ON/OFF keying, Pulse Amplitude Modulation (PAM), Pulse Width Modulation (PWM) and Pulse Position Modulation (PPM). The method may comprise superimposing the time-varying data signal on the modulated light at a data rate which

is greater than the frequency of modulation of the modulated light. The method may comprise superimposing the time-varying data signal on the modulated light at a data rate of 100 kb/s to 1 Mb/s, 1 Mb/s - 10 Mb/s or 10 Mb/s - 100 Mb/s, for example using ON/OFF keying. One skilled in the art will understand that the method may comprise using more complex schemes to achieve data transmission rates of the order of Gb/s or greater.

The method may comprise transmitting data using the light illuminating the scene from more than one direction. The method may comprise transmitting the same data from different directions, or different data from different directions. The method may comprise transmitting data from different directions at different frequencies. The method may comprise separating the data transmitted from different directions by frequency. The method may comprise separating the data transmitted from different directions by performing a Fourier transform on the detected signal.

The transmitter may include at least one of the optical sources used to illuminate the object. The receiver may comprise an optical detector.

The method may comprise identifying one or more objects in the photometric stereo video. The method may comprise tracking movement of the one or more objects in the photometric stereo video. The method may comprise tracking movement of the receiver. The method may comprise tracking the movement of the object and/or the receiver from the photometric stereo video.

At least one of the one or more objects may comprise a receiver, and the method may comprise transmitting data to the one or more receiver. The receiver may be within a field of view of the video camera. The receiver may be capable of moving in the field of view of the video camera.

The method may comprise transmitting data to the at least one receiver in response to the photometric stereo video. The method may comprise transmitting data to the at least one receiver, which data is representative of the position of at least one of the one or more objects. The method may comprise transmitting data to the at least one receiver in response to movement of at least one of the one or more objects in the photometric stereo video.

Transmitting the data to the receiver may permit the robot, agent or semi-autonomous device to which the receiver is attached to be informed of the position of the object and/or the receiver in the scene. Such a method may be used to monitor a scene for security and/or surveillance purposes.

The method may comprise using the plurality of optical sources to illuminate, in a flicker-free manner, the scene, whilst also illuminating the scene from the plurality of different directions.

The method may be performed before, during and/or after a manufacturing operation is performed on an object in the scene.

The object may comprise a sample, an item and/or a device such as an electronic device, an optoelectronic device and/or a photonic device.

The object may comprise at least one of a solid, liquid and a gas.

According to at least one aspect or to at least one embodiment there is provided a computer program or computer program product which, when executed on a processor, causes the processor to implement a method for use in photometric stereo-imaging, the method comprising:

illuminating a scene from a plurality of different directions;

repeatedly recording images of at least part of the scene illuminated from each different direction at a video frame rate; and

analysing the recorded images to create a photometric stereo video.

The computer program or computer program product may be provided on a carrier medium. The carrier medium may be tangible and/or non-transient.

BRIEF DESCRIPTION OF THE DRAWINGS

A wireless optical communication system and method for use in manufacturing operations, and a photometric stereo-imaging system and method, will now be described by way of non-limiting example only with reference to the drawings of which:

Figure 1A shows a wireless optical communication system for use in manufacturing operations;

Figure 1 B shows another wireless optical communication system for use in manufacturing operations;

Figure 2 shows a wireless optical communication method of using the system of Figure 1A or 1 B to control manufacturing operations;

Figure 3 shows a further wireless optical communication system for use in manufacturing operations;

Figure 4 shows a wireless optical communication method of monitoring and/or controlling a manufacturing operation using sensed data associated with a first apparatus;

Figure 5 shows a wireless optical communication system for use in controlling manufacturing operations using structured light;

Figure 6 shows another wireless optical communication system for use in manufacturing operations;

Figure 7 shows a subset of a Hadamard sequence of patterns;

Figure 8A shows two different signals detected when illuminating a scene using the subset of a Hadamard sequence of Figure 7;

Figure 8B shows two different data transmissions;

Figure 9 shows a method for use in determining positions associated with first and second apparatus;

Figure 10 shows a photometric stereo-imaging system;

Figures 1 1A shows modulation of the intensity of light used to illuminate an object from one direction when performing photometric stereo imaging; and

Figure 11 B shows a data signal superimposed on the modulated light of Figure 1 1A for use in data transmission whilst performing photometric stereo-imaging.

DETAILED DESCRIPTION OF THE DRAWINGS

Referring initially to Figure 1A, there is shown a wireless optical communication system 105 for use in manufacturing operations. The system 105 includes an optical transmitter arrangement 110, a first optical receiver arrangement 125a and a second optical receiver arrangement 125b. The first optical receiver arrangement 125a is located on a first apparatus 130a. The second optical receiver arrangement 125b is located on a second apparatus 130b.

The optical transmitter arrangement 110 has a first optical source 115a and a second optical source 1 15b. The first optical source 115a transmits or emits a first signal using a first light beam 120a which is detected by the first optical receiver arrangement 125a. Similarly, the second optical source 115b transmits or emits a second signal using a second light beam 120b which is detected by the second optical receiver arrangement 125b. The system 105 further includes a controller 135 which is configured to control the optical transmitter arrangement 110.

The light beams 120a-b are spatially distinct i.e. light beams 120a-b do not spatially overlap with each other. The fist optical receiver arrangement 125a therefore does not need to determine which light beams 120a-b are intended for the first optical receiver arrangement 125a or the first apparatus 130a, as the first optical receiver arrangement 125a can only detect the first light beam 120a. This means the first optical source 115a can securely communicate a first signal using the first light beam 120a to the first apparatus 130a without having to use a handshake protocol. The same is true for the second optical source 1 15b, the second signal, the second light beam 120b, the second optical receiver arrangement 125b and the second apparatus 130b.

Figure 1 B shows another wireless optical communication system 155 for use in controlling manufacturing operations. The system 155 includes an optical transmitter arrangement 160, a first optical receiver arrangement 175a, and a second optical receiver arrangement 175b. The first optical receiver arrangement 175a is located on a first apparatus 180a. The second optical receiver arrangement 175b is located on a second apparatus 180b.

The optical transmitter arrangement 160 transmits or emits a first signal using a first light beam 170a which is detected by the first optical receiver arrangement 175a. Similarly, the optical transmitter arrangement 160 transmits or emits a second signal using a second light beam 170b which is detected by the second optical receiver arrangement 175b. The system 155 further includes a controller 185 which is configured to control the optical transmitter arrangement 160.

The first apparatus 180a is a robot with an articulated arm 181. The second apparatus 180b is a machine tool. The robot 180a is commanded by the first signal using the first light beam 170a to perform a first operation by placing one part 182 on the machine tool 180b. The machine tool is commanded by the second signal using the second light beam 170b to perform a second operation by machining the part 182 which has been placed on the machining tool 170b. The first and second manufacturing operations of the robot 180a and the machining tool 180b are therefore co-ordinated.

Figure 2 shows a flow diagram of a wireless optical communication method of controlling manufacturing operations using the system 105 of Figure 1A. First, the controller 135 accepts an input from a human or computer 210. This input defines or specifies the manufacturing operations. Next, the controller 135 sends a command 220 to the optical transmitter arrangement 1 10. This command determines what signals the optical transmitter arrangement 1 10 transmits using the light beams 120a-b. The optical transmitter arrangement 1 10 then transmits 230a-b the first and second signals using the first and second light beams 120a-b.

The first optical receiver arrangement 125a then detects 241a the transmitted first light beam 120a. The first optical receiver arrangement 125a then determines the transmitted first signal and translates 242a the transmitted first signal 120a into a signal the first apparatus 130a can understand. The first optical receiver arrangement 125a then commands 243a the first apparatus 130a. The first apparatus 130a then performs 250a the first manufacturing operation.

The second optical receiver arrangement 125b similarly transmits 230b the second light beam 105b, which is similarly detected 241 b, the second signal is determined and translated 242b by the second optical receiver arrangement 125b, which then similarly commands 243b the second apparatus 130b, and the second apparatus 130b similarly performs 250b the second manufacturing operation.

Figure 3 shows a further wireless optical communication system 305 for use in manufacturing operations. The system 305 includes an optical transmitter arrangement 310, a first optical receiver arrangement 325a and a second optical receiver arrangement 325b. The first optical receiver arrangement 325a is provided with a first apparatus 330a. The second optical receiver arrangement 325b is provided with a second apparatus 330b. The optical transmitter arrangement 310 has a first optical source 315a and a second optical source 315b.

The first apparatus 330a includes a first apparatus optical transmitter arrangement 340a and a first sensor 332a. The second apparatus 330b includes a second apparatus optical transmitter arrangement 340b and a second sensor 332b.

The system 305 includes a system optical receiver arrangement 350, comprising a first system optical detector 350a and a second system optical detector

350b. Although the first and second optical detectors 350a, 350b are shown in Figure 3 provided with the first and second optical sources 315a, 315b, it should be understood that the first and second optical detectors 350a, 350b may be located separately or remotely from the first and second optical sources 315a, 315b.

The system 305 further includes a controller 335 which is configured for communication with the first and second optical sources 315a, 315b of the optical transmitter arrangement 310 and for communication with the first and second optical detectors 350a, 350b of the system optical receiver arrangement 350. The first optical source 315a transmits or emits a first signal using a first light beam 320a which is detected by the first optical receiver arrangement 325a. Similarly, the second optical source 315b transmits or emits a second signal using a second light beam 320b which is detected by the second optical receiver arrangement 325b.

The first apparatus optical transmitter arrangement 340a is emits or transmits a first return signal using a first return light beam 345a to the first system optical detector 350a. Similarly, the second apparatus optical transmitter arrangement 340b transmits or emits a second return signal using a second return light beam 345b to the second system optical detector 350b. Such a system may permit two-way communication between the controller 335 and the first and second apparatus 330a, 330b.

The first and/or second sensors 332a-b may be a temperature sensor, a pressure sensor, a position sensor, an accelerometer, a range finder, an image sensor, a camera such as a video camera, or a machine vision system. The first and/or second sensors 332a-b may be used to determine the progress of the first and/or second manufacturing operations by sensing or measuring one or more parameters. The first and/or second apparatus 330a-b may communicate the one or more sensed parameters to the first and second system optical detectors 350a-b using the first and second return light beams 345a-b.

Figure 4 shows a flow diagram of a method for use in controlling a first manufacturing operation performed by the first apparatus 330a shown in Figure 2.

The controller 335 commands 420 the first apparatus 330a to perform a first manufacturing operation. The command is sent from the controller 325 to the optical transmitter arrangement 310, which transmits a first signal using the first light beam 320a to the first optical receiver arrangement 325a. The first apparatus 330a then begins to perform 430 the first manufacturing operation.

The first apparatus 330a determines 440 the progress of the first manufacturing operation by sensing a parameters. The first apparatus 330a is fitted with a first sensor 332a, for example a position sensor or a temperature sensor. The first sensor 332a measures a parameter of the first apparatus 330a and/or the first manufacturing operation. The type of sensors required will be based on the nature of the first apparatus 330a and/or the first manufacturing operation, and it will be well understood by one skilled in the art which sensors are most appropriate for a given situation.

The first apparatus 330a then determines 450 whether the first manufacturing operation is complete. If the first manufacturing operation is complete 451 , then the first apparatus 330a stops 460 performing the first manufacturing operation. If the first manufacturing operation is not complete 452, then the first apparatus 330a determines 470 whether the sensed parameter is within an acceptable range.

If the sensed parameter is 471 within an acceptable range, then the first apparatus 330a continues to perform 430 the first manufacturing operation. If the sensed parameter is not 472 within an acceptable range, then the first manufacturing operation is modified 480 based on the sensed parameter, and the first apparatus 330a again determines 440 the progress of the first manufacturing operation by sensing a parameter.

The modification 480 of the first manufacturing operation may be performed either by the first apparatus 330a itself, or the sensed parameter may be communicated to the controller 335 using the return signal 345a, and the controller 335 may then decide how to modify the first manufacturing operation and command the first apparatus 330a accordingly. The computation power and the decision making ability to modify 480 the first manufacturing operation may therefore be located on the first apparatus 330a itself and/or on the controller 335.

Figure 5 shows a wireless optical communication system 505 for use in manufacturing operations where the optical transmitter arrangement 510 has three optical sources 515a-c which are structured light transmitters. The optical transmitter arrangement 510 is coupled to, and controlled by, the controller 535. Each structured light optical transmitter 515a-c sends a separate structured light beam 520a-c to a corresponding separate optical receiver arrangement 525a-c on a corresponding separate apparatus 530a-c. Each optical receiver arrangement 525a-c is an image sensor, able to detect the corresponding structured light beam 520a-c.

The structured light beams 520a-c may comprise a pattern of light, or a series of patterns of light. The intensity of the structured light beams 520a-c may also vary with time. As temporal and spatial variations in the structured light beams 520a-c can be used to encode data, the structured light beams 520a-c are able to carry more data

than an unstructured light beam which uses only a temporal variation in the light beam to transmit data, and so the data transfer rate between the optical receiver arrangement 510 and the apparatus 530a-c is increased.

Figure 6 shows a wireless optical communication system 605 for use in manufacturing operations. The system 605 includes a structured light optical transmitter arrangement 610 in the form of a micro-LED array 610 which includes four LEDs 615a-d. The system also includes optical receiver arrangements 625a-d and apparatus optical transmitter arrangements 640a-d provided with apparatus 630a-d. The system 605 also includes a system optical receiver arrangement 650 which includes four system optical detectors 651 a-d. The system 605 further includes a controller 635 which is configured for communication with the optical transmitter arrangement 610 and the system optical receiver arrangement 650.

In use, each LED of the micro-LED array 610 transmits an independent light signal using a corresponding light beam 620a-d to a different optical receiver arrangement 625a-d on a different apparatus 630a-d. The apparatus optical transmitter arrangements 640a-d transmits an individual apparatus return signal using a corresponding return light beam 645a-d to the optical detectors 651 a-d of the system optical receiver arrangement 650. The light beams 620a-d are spatially distinct from each other. The scene 657 and the scene boundaries 658 are defined by the area covered by the light beams 620a-d. Outside the scene boundaries 658 the intensity of light transmitted from the optical transmitter arrangement 610 is below a threshold amount.

Figure 7 shows a series of patterns 700 which can be transmitted by a 16 by 16 array of LEDs such that each LED transmits a unique series of flashes. The series of patterns 700 is a subset of a Hadamard sequence. In each pattern 1-16 half of the LEDs are on and half of the LEDs are off. The odd-numbered patterns are immediately followed in the series 700 by an opposing even-numbered pattern. For example, in pattern 1 the left half of LEDs are on and the right half of LEDs are off, and in pattern 2, the left half of LEDs are off and the right half of LEDs are on. This Manchester encoding ensures that each LED is on for half the time and off for half the time, so the average illumination across the 16 by 16 array of LEDs is constant. If the Manchester encoding was not used, and only the odd-numbered patterns were used, the top left LED would always be on, and the bottom right LED would always be off, which would result in an uneven illumination across the LED array over time.

Figure 8A shows the unique response 855a which is detected by an optical receiver arrangement in a first position in response to the series of patterns 700, and a different unique response 855b for an optical receiver arrangement in a second position in response to the series of patterns 700. The series of patterns 700 begins with a start pattern S in which all the LEDs are on, and finished with an end pattern E, in which all the LEDs are off. During the start pattern S, the intensity of the light detected by the optical receiver arrangement is above the light intensity threshold required for the optical receiver arrangement to determine the light is on. During the end pattern E, the intensity of light detected by the optical receiver arrangement is at its lowest intensity. This indicates the end of the pattern sequence 700. . An optical receiver arrangement can determine which part of a scene 657 it is in from the response 855a-b to the series of patterns 700. The optical receiver arrangement uses the detection of the start pattern S and the end pattern E to synchronise to the series of patterns 700.

Figure 8B shows the unique light signal 820a which is detected by an optical receiver arrangement in a first position, and a different unique light signal 820b which is detected by an optical receiver arrangement in a second position. The series of patterns 700 are not being transmitted whilst the light signals 820a-b are being transmitted. Light signals 820a-b are sent simultaneously by different LEDs.

Figure 9 shows a flow diagram of a method of transmitting the first and second signals using first and second light beams 620a-b which includes determination of the location of the first and second optical receiver arrangements 625a-b. When the first and second light beams 620a-b are directional beams, it is necessary to know the positions of the first and second optical receiver arrangements 625a-b to communicate the correct beams 620a-b to the correct apparatus 630a-b.

The optical transmitter arrangement 610 must first determine whether the positions of the first and second optical receiver arrangements 630a-b are known 910. If the positons of the first and second optical receiver arrangements 630a-b are known 912, than the first and second light beams 620a-b are simply transmitted 930 to the first and second apparatus 630a-b via the first and second optical receiver arrangements 625a-b. However, if the positons of the first and second optical receiver arrangements 630a-b are not known 914, the optical transmitter arrangement 610 transmits 940 a Hadamard pattern sequence 700.

The first optical receiver arrangement 625a then receives 952a the Hadamard pattern sequence 700 at the location of the first optical receiver arrangement 625a. The first optical receiver arrangement 625a uses the received 952a Hadamard pattern sequence 700 to determine 954a the position of the first optical receiver arrangement 625a. The first apparatus optical transmitter arrangement 640a then transmits 956a the determined position of the first optical receiver arrangement 625a to the system optical detector 651 a. The optical transmitter arrangement 610 then transmits 960a the first signal 820a using the first light beam 620a to the first optical receiver arrangement 625a.

Similarly, the second optical receiver arrangement 625b receives 952b the Hadamard pattern sequence 700 and determines 954b its position. The second apparatus optical transmitter arrangement 640b then transmits 956b that position information to the system optical detector 651 b. The optical transmitter arrangement 610 then transmits 960b the second signal 820b using the second light beam 620b to the second optical receiver arrangement 625b.

Figure 10 shows a photometric stereo-imaging system 1070 which has an optical transmitter arrangement comprising four optical sources in the form of four LEDs 1072a-d, a video camera 1074, and a controller 1078. The LEDs 1072a-d are arranged in a square configuration, separated by a distance d, which is about 30 cm. The camera 1074 is in the centre of the LEDs 1072a-d. The LEDs 1072a-d transmit or emit light which illuminates a scene 1077 and an object 1076 which is in the scene 1077. The object 1076 is a distance L, about 0.5 m, from the camera 1074. The LEDs 1072a-d illuminate both the scene 1077 and the object 1076 from different angles. The camera 1074 images at least part of the scene 1077 which includes the object 1076 as the scene 1077 and the object 1076 are illuminated by the LEDs 1072a-d. The camera 1074 has a resolution of 640 χ 460 and a frame rate of 60 frames per second (fps).

The frame rate of the camera 1074 is high enough that images of at least part of the scene 1077 and the object 1076 can be captured quickly enough to create a photometric stereo video of at least part of the scene 1077 and the object 1076 in motion.

The camera 1074 is coupled to the controller 1078. The controller 1078 analyses the images from the camera 1074 to create the photometric stereo video of at least part of the scene 1077 and the object 1076. The controller 1078 is also coupled to the LEDs 1072a-d. The controller 1078 controls the light transmitted or emitted by the LEDs 1072a-d.

To analyse the images from the camera 1074 to create the photometric stereo video, it is necessary to know the illumination of at least part of the scene and the object 1076 from each LED 1072a-d individually. This can be done by operating the LEDs 1072a-d sequentially, and capturing an individual image on the camera 1074 of at least part of the scene 1077 and the object 1076 whilst at least part of the scene 1077 and the object 1076 are illuminated by each LED 1072a-d one at a time. Alternatively, all the LEDs 1072a-d may be operated simultaneously, and the intensity of the light emitted by each LED 1072a-d varied sinusoidally at a different frequency. The frequency of modulation for each LED 1072a-d is selected to be less than half the frame rate of the camera 1074. The controller 1078 can then perform a Fourier transform on the images captured by the camera 1074 to separate the images captured when at least part of the scene 1077 and the object 1076 are illuminated by different LEDs 1072a-d in order to generate the photometric stereo video. As the LEDs 1072a-d are always illuminating at least part of the scene and the object, there is no need to synchronise the illumination of the LEDs 1072a-d with the frame rate of the camera 1074.

The photometric stereo-imaging system 1070 can be used in conjunction with the systems for use in controlling manufacturing operations shown in Figures 1 , 5 or 6. For example, the object 1076 may comprise the first apparatus 130a or a part of the first apparatus 130a, the second apparatus 130b or a part of the second apparatus 130a. The object 1076 may comprise a sample, image or object upon which the first and/or second manufacturing operations are performed. At least one of the LEDs 1072a-d could be one of the optical sources 115a-b of the system 105 of Figure 1. Similarly, at least one of the LEDs 1072a-d could be replaced with one of the optical sources 515a-c of system 505 shown in Figure 5, or with the optical transmitter arrangement 610 of system 605 shown in Figure 6.

Alternatively, the photometric stereo-imaging system 1070 may be used completely separately from the systems shown in Figures 1 , 5 or 6, or separately of any manufacturing operations. For example, the photometric stereo-imaging system 1070 may be used to monitor at least part of a scene 1077 for security and/or surveillance purposes. The photometric stereo-imaging system 1070 may include a transmitter and a receiver. The transmitter may be configured for communication with the controller 1078. The transmitter may include at least one of the LEDs 1072a-d. The receiver may be an optical detector 1085. The receiver may be provided with a robot, an agent such as a security officer, and/or a semi-autonomous device.

Figure 1 1A shows the sinusoidally varying illumination 1 180 from one of the LEDs 1072a-d, and Figure 11 B shows a data signal 1 182 superimposed by the

controller 1078 on the sinusoidally varying illumination 1 180 from one of the LEDs 1072a-d for transmission to the optical detector 1085. The data signal 1 182 may carry information relating to one or more photometric stereo-images generated by the photometric stereo-imaging system 1070. The data signal 1 182 may carry information relating to a position of the object 1076 and/or the optical detector 1085. Transmitting the data signal 1 182 from at least one of the LEDs 1072a-d to the optical detector 1085 may permit the robot, agent or semi-autonomous device to which the optical detector 1085 is attached to be informed of the position of the object 1076 and/or the optical detector 1085 in the scene 1077.

The illumination 1 180 varies with a frequency of F1 and by an amplitude of A1 .

The illumination 1 180 has a non-zero background 1 181 , such that the LED 1072a is always transmitting or emitting some light. One of ordinary skill in the art will understand that the data signal 1 182 is transmitted at a data rate F2 which is high enough that the camera 1074 is unable to detect the data signal 1 182. Additionally, the data signal 1 182 may have an amplitude A2 which is small enough that the camera 1074 is unable to detect the data signal 1 182. In Figure 1 1 B, the data signal 1 182 is shown as being encoded using amplitude-shift keying (ASK) modulation. In other embodiments, the data signal 1 182 may be encoded using ON/OFF keying, Frequency Shift Keying (FSK), Phase Shift Keying (PSK), Pulse Amplitude Modulation, Pulse Position Modulation (PPM), or any other suitable encoding method.

In one or more further embodiments, instead of using FDMA as described above, a specifically developed variant of FDMA, called Manchester-encoded binary FDMA (MEB-FDMA), can be used for the same purpose. In MEB-FDMA, each emitter is modulated with on-off keying at a bit rate equal to or less than the camera frame rate, and the FDMA frequencies are oversampled at this bitrate. Furthermore, each bit is Manchester-encoded. This approach may enable flicker-free operation and remove the need for synchronisation between the illumination sources and the camera. It enables visible light positioning and photometric stereo-imaging at the same time using the same illumination. The received signal is decoded via matrix-multiplication with a decoding matrix that can be determined upon system manufacture or installation. The decoding matrix for each emitter is constructed from the emitter modulation as follows. Let Sjj e [-1 1 ] be the modulation of the ith emitter, where the index j denotes the timeslot. An nxn matrix S(l) is constructed via:

*k,j ~ si,l+ 0'- l+fc)%n

where % is the modulo operator. The decoding matrix D(l) for the i emitter is then obtained by stabilised Gram-Schmidt orthogonalisation of the matrix S(l). The received signal strength of the ith emitter can be retrieved by matrix-multiplication of D(l) with the received signal.

It will be appreciated by one skilled in the art that the systems of Figures 1 , 5 and 6 are interchangeable, and that one or more of the features from different wireless optical communication systems can be combined together.

It will be appreciated by one skilled in the art that a Fourier transform is a well-known mathematical operation. One skilled in the art will understand that a discrete Fourier transform and/or a fast Fourier transform may be equivalent to a Fourier transform.

It will be appreciated by one skilled in the art that the particular geometry and scale of the photometric stereo-imaging apparatus shown is exemplary only, and that the spacing of the LEDs and the object can be scaled up or down. One skilled in the art will understand how to scale the photometric stereo-imaging apparatus shown to a room or warehouse scale.