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1. WO2020117277 - MIRROR ASSEMBLY FOR LIGHT STEERING

Note: Text based on automatic Optical Character Recognition processes. Please use the PDF version for legal matters

[ EN ]

WHAT IS CLAIMED IS:

1. An apparatus comprising a Light Detection and Ranging (LiDAR) module, the LiDAR module comprising:

a light source;

a receiver; and

a semiconductor integrated circuit comprising a microelectromechanical system (MEMS) and a controller,

wherein the MEMS comprises:

an array of first rotatable mirrors to receive and reflect the light beam from the light source;

a second rotatable mirror to receive the light beam reflected by the array of first rotatable mirrors;

an array of first actuators configured to rotate each rotatable mirror of the array of first rotatable mirrors; and

a second actuator configured to rotate the second rotatable mirror;

and

wherein the controller is configured to control the array of first actuators and the second actuator to rotate, respectively, the array of first rotatable mirrors and the second rotatable mirror to set a first angle of light path with respect to a first dimension and to set a second angle of the light path with respect to a second dimension orthogonal to the first dimension to perform at least one of: reflecting light from the light source along the light path, or reflecting input light propagating along the light path to the receiver.

2. The apparatus of claim 1, wherein the light source is a laser diode.

3. The apparatus of claim 1, wherein the light comprises a first light signal; and wherein the controller is configured to:

control the light source to transmit the light including the first light signal at a first time;

control the array of first actuators and the second actuator to output the light including the first light signal along the light path towards an object;

control the array of first the array of first actuators and the second actuator to select the input light including a second light signal propagating along the light path from the object;

receive, via the receiver, the second light signal at a second time; and determine a location of the object with respect to the apparatus based on a difference between the first time and the second time, the first angle, and the second angle.

4. The apparatus of claim 1, wherein the array of first rotatable mirrors and the second rotatable mirror are formed on a surface of a semiconductor substrate of the

semiconductor integrated circuit.

5. The apparatus of claim 4, further comprising a third mirror facing the array of first rotatable mirrors and the second rotatable mirror and configured to reflect the light reflected from the array of first rotatable mirrors towards the second rotatable mirror.

6. The apparatus of claim 5, wherein the third mirror is separated from the surface of the semiconductor substrate by a first distance;

wherein the array of the first rotatable mirrors and the second rotatable mirror are separated by a second distance; and

wherein the first distance and the second distance are set based on an angle of incidence of the light from the light source with respect to the first rotatable mirror.

7. The apparatus of claim 1, further comprising a collimator lens positioned between the light source and the first rotatable mirror,

wherein the collimator lens has a pre-determined aperture length.

8. The apparatus of claim 7, wherein each dimension of the array of first rotatable mirrors and of the second rotatable mirror is substantially equal to the aperture length.

9. The apparatus of claim 1, wherein the array of first rotatable mirrors are formed on a first surface of a first semiconductor substrate of the semiconductor integrated circuit;

wherein the second rotatable mirror is formed on a second surface of a second semiconductor substrate of the semiconductor integrated circuit; and

wherein the first surface faces the second surface.

10. The apparatus of claim 1, wherein a mass of each rotatable mirror of the array of first rotatable mirrors is smaller than a mass of the second rotatable mirror;

wherein the controller is configured to adjust a first rotation angle of each rotatable mirror of the array of first rotatable mirrors at a first frequency; and

wherein the controller is configured to adjust a second rotation angle of the second rotatable mirror at a second frequency higher than the first frequency, the second frequency being substantially equal to a natural frequency of the second rotatable mirror.

11. The apparatus of claim 10, wherein each actuator of the array of first actuators and the second actuator comprises a rotary drive; and

wherein the controller is configured to adjust the first rotation angle and the second rotation angle based on adjusting, respectively, a first torque provided by each actuator of the array of first actuators and a second torque provided by the second actuator.

12. The apparatus of claim 11, wherein each actuator of the array of first actuators and second actuator comprises at least one of: a comb drive, a piezoelectric device, or an electromagnetic device.

13. The apparatus of claim 1, further comprising motion sensors, each motion sensor being coupled with each rotatable mirror of the array of first rotatable mirrors and the second rotatable mirror and configured to measure a rotation angle of each of the array of first rotatable mirrors and the second rotatable mirror;

wherein the controller is configured to:

receive data from the motion sensors; and

determine a signal for each actuator of the first rotatable mirror and the second rotatable mirror based on the data such that each rotatable mirror of the array of first rotatable mirrors and the second rotatable mirror rotate at, respectively, a first target angle and a second target angle.

14. A method, comprising:

determining a first angle and a second angle of a light path, the light path being one of a projection path for output light or an input path of input light, the first angle being with respect to a first dimension, the second angle being with respect to a second dimension orthogonal to the first dimension;

controlling an array of first actuators to rotate an array of first rotatable micro-mirrors of a microelectromechanical system (MEMS) to set the first angle;

controlling a second actuator to rotate a second rotatable mirror of the MEMS to set the second angle;

projecting, using a light source, a light beam including a light signal towards a mirror assembly, the mirror assembly comprising an array of first rotatable mirrors and a second rotatable mirror; and

with the array of first rotatable mirrors setting the first angle and the second rotatable mirror setting the second angle, using the array of first rotatable mirrors and the second rotatable mirror to perform at least one of: reflecting the output light from the light source along the projection path towards an object, or reflecting the input light propagating along the input path to a receiver.

15. The method of claim 14, further comprising:

controlling the light source to transmit the output light including a first light signal at a first time;

controlling the array of first actuators and the second actuator to output the output light including the first light signal along the light path towards an object;

controlling the array of first the array of first actuators and the second actuator to select the input light including a second light signal propagating along the light path from the object;

receiving, via the receiver, the second light signal at a second time; and determining a location of the object based on a difference between the first time and the second time, the first angle, and the second angle.

16. The method of claim 14, further comprising:

adjusting a first rotation angle of each rotatable mirror of the array of first rotatable mirrors at a first frequency; and

adjusting a second rotation angle of the second rotatable mirror at a second frequency higher than the first frequency, the second frequency being substantially equal to a natural frequency of the second rotatable mirror.

17. The method of claim 16, further comprising:

receiving, from motion sensors, information indicating the first rotation angle of each rotatable mirror of the array of first rotatable mirrors and the second rotation angle of the second rotatable mirror;

adjusting first control signals to the array of first actuators based on a difference between the first rotation angle and a first target rotation angle; and

adjusting a second control signal to the second actuator based on a difference between the second rotation angle and a second target rotation angle.

18. A non-transitory computer readable medium storing instructions that, when executed by a hardware processor, causes the hardware processor to:

determine a first angle and a second angle of a light path, the light path being one of a projection path for output light or an input path of input light, the first angle being with respect to a first dimension, the second angle being with respect to a second dimension orthogonal to the first dimension;

control an array of first actuators to rotate an array of first rotatable mirrors of a microelectromechanical system (MEMS) to set the first angle;

control a second actuator to rotate a second rotatable mirror of the MEMS to set the second angle;

project, using a light source, a light beam including a light signal towards a mirror assembly, the mirror assembly comprising an array of first rotatable mirrors and a second rotatable mirror; and

with the array of first rotatable mirrors setting the first angle and the second rotatable mirror setting the second angle, use the array of first rotatable mirrors and the second rotatable mirror to perform at least one of: reflecting the output light from the light source along the projection path towards an object, or reflecting the input light propagating along the input path to a receiver.

19. The non-transitory computer readable medium of claim 18, further comprising instructions that, when executed by the hardware processor, cause the hardware processor to:

control the light source to transmit the output light including a first light signal at a first time;

control the array of first actuators and the second actuator to output the output light including the first light signal along the light path towards an object;

control the array of first the array of first actuators and the second actuator to select the input light including a second light signal propagating along the light path from the object;

receive, via the receiver, the second light signal at a second time; and determine a location of the object based on a difference between the first time and the second time, the first angle, and the second angle.

20. The non-transitory computer readable medium of claim 18, further comprising instructions that, when executed by the hardware processor, cause the hardware processor to:

adjust a first rotation angle of each rotatable mirror of the array of first rotatable mirrors at a first frequency; and

adjust a second rotation angle of the second rotatable mirror at a second frequency higher than the first frequency, the second frequency being substantially equal to a natural frequency of the second rotatable mirror.