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2. (WO2014072818) MINIATURE OPTICAL ZOOM LENS
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MINIATURE OPTICAL ZOOM LENS

CROSS REFERENCE TO RELATED APPLICATIONS

[0001] This patent document claims the benefit of priority of U.S. Provisional Patent Application No. 61/724,221, entitled "INTEGRATED ELASTIC SUSPENSION

PLATFORM WITH OPTICAL COMPONENTS" filed on November 8, 2012, and of U.S. Provisional Patent Application No. 61/874,333, entitled "MINIATURE OPTICAL ZOOM LENS" filed on September 5, 2013. The entire contents of the aforementioned patent applications are incorporated by reference as part of the disclosure of this patent document.

BACKGROUND

[0002] The present disclosure relates to optical systems and methods of manufacturing thereof and more particularly to zoom lens systems and methods of manufacturing.

[0003] The alignment of components in an optical system is an important factor in achieving optimal system performance and a desired image quality. Proliferation of small-scale optical systems for use in, for example, a variety of handheld devices, such as cell phones and hand-held cameras, places additional challenges on alignment tolerances due to the small dimensions of optical components within such devices. As such, there exists a need to improve the alignment of components in an optical system in order to achieve optimal performance while minimizing the system's overall form factor. Further, it is essential to minimize the size of the optical systems that are used in, for example, consumer devices, such as phones and hand-held cameras.

SUMMARY

[0004] The disclosed embodiments relate to systems and methods for improving the alignment of optical components within an optical systems. The disclosed embodiments further relate to miniature zoom lens systems and methods for their manufacture and assembly that allow the production of small lens systems in a streamlined fashion. In some exemplary embodiments, the disclosed embodiments are used to align varifocal lenses of an optical system to decrease the overall size of the system while optimizing its performance.

[0005] In systems with moving optical components, such as zoom lens systems, alignment of optical components is complicated due to their mobility. In some systems, optical components are moved only along the optical axis (i.e., along the z-axis), which makes alignment along the optical axis particularly important. Alternatively, or additionally, in some systems, such as in an Alvarez lens configuration, optical components can move perpendicular to the optical axis, which makes proper alignment of the elements in multiple dimensions even more challenging. Alignment issues can be further exacerbated in systems where components with aspheric or free-form surfaces are used since such components may not have an axis of symmetry.

[0006] The disclosed embodiments seek to provide methods and system for properly aligning optical components by moving them both along and perpendicular to the z-axis (i.e., the optical axis) in order to minimize the length of the optical path while maintaining the quality of images captured by such optical systems. By using freeform lenses, such as Alvarez lenses, it is possible to achieve optimal focusing and zooming of an image within a diminutive amount of space by actuating lenses at right angles to the z-axis in addition to moving the lenses and other optical components along the z-axis.

[0007] This reduction in the optical path's length enables a reduction in the overall size of the optical system, since less space would be required to carry an image through the system's lenses. As such, optimized alignment of the lens elements in a miniature optical system in accordance with the disclosed embodiments leads to smaller optical systems in devices that use such systems, such as cell phones and digital cameras. This reduction in optical system size allows such devices to have more room for other components, such as batteries and processors, or allows them to achieve an overall reduction in size altogether. As these devices become smaller and smaller, the need for such miniaturization of key technological components will be paramount to maintaining a competitive edge for those companies that manufacture and sell such devices.

[0008] One aspect of the disclosed embodiments relates to an integrated optical device that includes an elastic suspension fixture fabricated using a first process, and an optical element integrated into the elastic suspension fixture. The optical element is fabricated using a second process. In one exemplary embodiment, the first process comprises one of the following processes: an injection molding process, an in- mold decoration process, a hot stamping process, a metal stamping process, a micro-fabrication process that produces a chip-based mold, or an insert molding process. In another exemplary embodiment, the second process comprises one of the following processes: an injection molding process, a casting from a mold process, an in-mold decoration process, a hot stamping process, a metal stamping process, a micro-fabrication process that produces a chip-based mold, or an insert molding process.

[0009] According to one exemplary embodiment, the integrated optical device further includes one or more of the following: a frame, one or more alignment structures, an actuator configured to displace the optical element, one or more additional optical elements, one or more additional elastic elements, and one or more rigid elements. In yet another exemplary embodiment, the elastic fixture is configured to allow movement of the optical element in one or more directions. In still another exemplary embodiment, the elastic fixture is configured to allow movement of the optical element in three dimensions.

[0010] In one exemplary embodiment, the integrated optical device further includes an actuator configured to displace the elastic feature and to thereby displace the optical element. In another exemplary embodiment, the optical element comprises at least one of the following surfaces: a spheric surface, an aspheric surface, or a free-form surface.

[0011] Another aspect of the disclosed embodiments relates to a zoom lens that includes the above noted integrated optical device. Yet another aspect of the disclosed embodiments relates to a handheld electronic device comprising the above noted integrated optical device.

[0012] Another aspect of the disclosed embodiments relates to a method for fabricating an integrated optical device, that includes obtaining a first mold that is structured to form an elastic suspension fixture, injecting a first injection material into the first mold, and placing a second mold in contact with the first mold and the first injection material within the first mold, where the second mold is structured to form an optical element. The method also includes injecting a second injection material into the second mold, removing the second mold, and removing the first mold to obtain the elastic suspension fixture with the optical element integrated thereto.

[0013] In one exemplary embodiment, the first injection material comprises a first polymer suitable for formation of the elastic suspension fixture, and the second injection material comprises a polymer suitable for formation of the optical element. In another exemplary embodiment, the method further includes further refining structure of the integrated optical device using a precision machining tool. In still another exemplary

embodiment, the method further includes, prior to removing the first mold, placing a third mold in contact with the first mold and the first injection material, where the third mold is structured to form an additional element, and injecting a third injection material into the third mold.

[0014] According to another exemplary embodiment, the additional element is one of: an additional optical element, an additional elastic fixture; or a rigid fixture. In one exemplary embodiment, the additional element is an alignment fixture. In yet another exemplary embodiment, components within the integrated optical devices are positioned according to a tolerance in the range of 1 to 5 microns. In another exemplary embodiment, the third injection material is the same material as one of the first injection material and the second injection material.

[0015] In one exemplary embodiment, the first mold is additionally structured to comprise a groove for placement of an actuation mechanism. In another exemplary embodiment, the above method further includes integrating a metallic frame into the elastic suspension fixture. In another exemplary embodiment, the metallic frame is formed using a metal stamping technique.

[0016] Another aspect of the disclosed embodiments relates to a method for fabricating an integrated optical device that includes oobtaining a first mold that is structured to form an elastic suspension fixture and an optical element, injecting a first injection material into the first mold, injecting a second injection material into the first mold, and removing the first mold to obtain the elastic suspension fixture with the optical element integrated thereto.

[0017] Another aspect of the disclosed embodiments relates to a method for fabricating an integrated optical device that includes obtaining a mold that is structured to form an elastic suspension fixture and to house an optical element, placing the optical element in the mold, injecting a first injection material into the mold to form an elastic suspension fixture, and removing the mold to obtain the elastic suspension fixture with the optical element integrated thereto. In one exemplary embodiment, the optical element is cast from a mold prior to placing the optical element in the mold.

[0018] Another aspect of the disclosed embodiments relates to a miniature zoom lens system that includes a first prism positioned to receive incident light from an entrance to the miniature lens system through a first face of the first prism and to bend the received light by approximately 90 degrees before allowing the light to exit from a second face of the first prism, and at least a first varifocal lens positioned to receive the light that exits the second face of the prism. The miniature zoom lens system further includes at least one base lens positioned to receive the light after passing through the first varifocal lens, a detector positioned to receive the light after passing through the base lens, and a first actuator configured to move the first varifocal lens in at least a direction perpendicular to propagation axis of the light passing through the first varifocal lens.

[0019] In one exemplary embodiment, at least one face of the first prism has a freeform surface. In another exemplary embodiment, the first varifocal lens is one of the following: a liquid crystal lens, a liquid lens, or an Alvarez-like lens. In another exemplary embodiment, the detector comprises a complementary metal-oxide semiconductor (CMOS). In yet another exemplary embodiment, the first actuator comprises one of a coil or a magnet. In still another exemplary embodiment, the above miniature zoom lens system includes a structural platform to allow one of the following to be directly molded onto, fabricated onto, or integrated with the structural platform: the first prism, a second prism, the first varifocal lens, or a second varifocal lens. In one exemplary embodiment, the structural platform comprises a spring flexure element. In another exemplary embodiment, thee structural platform includes a frame and an arm.

[0020] According to another exemplary embodiment, the structural platform frame comprises a lead frame metal structure that is one or more of: a metal-stamped structure, a laser-cut structure, a milled structure, an etched structure, or a molded structure. In such an exemplary embodiment, the arm is molded on the lead frame structure, and one or more of the first prism, a second prism, the first varifocal lens, or a second varifocal lens is molded onto the lead frame.

[0021] In one exemplary embodiment, a wafer-level optical component with a preformed lens element is bonded to the platform. In another exemplary embodiment, the first actuator is a voice-coil actuator with a bidirectional drive. In yet another exemplary embodiment, the miniature zoom lens system also includes a second actuator configured to move an optical component other than the first varifocal lens within the miniature zoom lens system. In still another exemplary embodiment, the second actuator and the first actuator are configured to displace both the optical component other than the first varifocal lens and the first varifocal lens by the same distance and in the same direction. In one exemplary embodiment, the optical component other than the first varifocal lens is one of: a second varifocal lens, the at least one base lens, the first prism, or a second prism.

[0022] According to another exemplary embodiment, the first varifocal lens has a rectangular or an oval-shaped cross section encompassing only an essential active area of the first varifocal lens. In another exemplary embodiment, the miniature zoom lens system further includes a second varifocal lens positioned to receive the light exiting the first varifocal lens before reaching the at least one base lens. In still another exemplary embodiment, the second varifocal lens has a rectangular or an oval-shaped cross section encompassing only an essential active area of the second varifocal lens. In yet another exemplary embodiment, both the first and the second varifocal lenses are movable with respect to one another so as to provide optical zoom capability for the lens system.

[0023] In one exemplary embodiment, the at least one base lens is configured to move along optical axis of the base lens so as to provide optical focusing ability for the lens system through only movement of the base lens. In another exemplary embodiment, one or more of the first varifocal lens, the second varifocal lens or the at least one base lens is a liquid lens, a liquid crystal lens, a MEMS-based lens, an Alvarez-like lens, a piezo-based lens, or a combination thereof. In another exemplary embodiment, the spring flexure is one of a simple beam flexure or a cascaded beam flexure.

[0024] Another aspect of the disclosed embodiments relates to a miniature zoom lens system that includes a first prism positioned to receive incident light from an entrance to the miniature lens system through a first face of the first prism and to bend the received light by approximately 90 degrees before allowing the light to exit from a second face of the first prism, and a first varifocal lens positioned to receive the light that exits the second face of the prism. Such a miniature zoom lens system also incudes a second varifocal lens positioned to receive the light that exits first varifocal lens, at least one base lens positioned to receive the light after passing through the second varifocal lens, a second prism positioned to receive the light that exits the at least one base lens through a first face of the second prism and to bend the light received by the second prism by approximately 90 degrees before allowing the light to exit from a second face of the second prism, a detector positioned to receive the light after exiting the second prism, and at least one actuator configured to move one or both of the first varifocal and second varifocal lenses in at least a direction perpendicular to propagation axis of the light passing through the first or the second varifocal lenses.

[0025] Another aspect of the disclosed embodiments relates to a miniature zoom lens system that includes a first varifocal lens positioned to receive the incident light from an entrance to the miniature lens system, a first prism positioned to receive the light that exits the first varifocal lens through a first face of the first prism and to bend the light received by the first prism by approximately 90 degrees before allowing the light to exit from a second face of the first prism, a second varifocal lens positioned to receive the light that exits first prism, at least one base lens positioned to receive the light after passing through the second varifocal lens, a second prism positioned to receive the light that exits the at least one base lens through a first face of the second prism and to bend the light received by the second prism by approximately 90 degrees before allowing the light to exit from a second face of the second prism, a detector positioned to receive the light after exiting the second prism, and at least one actuator configured to move one or both of the first varifocal and second varifocal lenses in at least a direction perpendicular to propagation axis of the light passing through the first or the second varifocal lenses.

[0026] In one exemplary embodiment, the second prism is orientated such as to allow placement of the detector on the same side of the miniature zoom lens system as the entrance to the miniature zoom lens system. In another exemplary embodiment, the second prism is orientated such as to allow placement of the detector on a side of the miniature zoom lens system that is opposite to the entrance to the miniature zoom lens system.

[0027] Another aspect of the disclose embodiments relates to a miniature zoom lens system that includes a first varifocal lens positioned to receive the incident light from an entrance to the miniature lens system, a first prism positioned to receive the light that exits the first varifocal lens through a first face of the first prism and to bend the light received by the first prism by approximately 90 degrees before allowing the light to exit from a second face of the first prism, a second varifocal lens positioned to receive the light that exits first prism, at least one base lens positioned to receive the light after passing through the second varifocal lens, a detector positioned along the optical axis of the at least one base lens to receive the light after exiting the at least one base lens, and at least one actuator configured to move one or both of the first varifocal and second varifocal lenses in at least a direction perpendicular to propagation axis of the light passing through the first or the second varifocal lenses.

[0028] In one exemplary embodiment, the first varifocal lens and the first prism are formed as an integrated structure thereby reducing optical path length of light propagating through the miniature lens system. In another exemplary embodiment, one or more optical elements of the first varifocal lens are positioned to configure the first varifocal lens as a lens with a negative optical power, and one or more optical elements of the second varifocal lens are positioned to configure the second varifocal lens as a lens with a positive optical power.

[0029] In yet another exemplary embodiment, one or more optical elements of the first varifocal lens are positioned to configure the first varifocal lens as a lens with a positve optical power, and one or more optical elements of the second varifocal lens are positioned to configure the second varifocal lens as a lens with a negative optical power. In still another exemplary embodiment, one or more optical elements of the first varifocal lens are movable so as to allow an optical power of the first varifocal lens to change in response to the movement of the one or more optical elements of the first varifocal lens. In one exemplary embodiment, one or more optical elements of the second varifocal lens are movable so as to allow an optical power of the second varifocal lens to change in response to the movement of the one or more optical elements of the first varifocal lens.

[0030] Another aspect of the disclosed embodiments relate to an Alvarez lens configuration that includes a first optical element and a second optical element, where each optical element includes two surfaces that are substantially perpendicular to an optical axis of the lens configuration, and a first surface of each the optical elements is a plane surface and a second surface of each of the optical elements is a surface characterized by a polynomial. The first optical element is positioned at a particular distance from the second optical element such that the second surface of the first optical element faces the second surface of the second optical element, where each of the first and the second optical elements is configured to move substantially perpendicular to the optical axis.

[0031] Another aspect of the disclosed embodiments relate to an Alvarez lens configuration that includes a first optical element and a second optical element, where each optical element includes two surfaces that are substantially perpendicular to an optical axis of the lens configuration. A first surface of each the optical elements is a freeform surface and a second surface of each of the optical elements is a surface characterized by a polynomial. The first optical element is positioned at a particular distance from the second optical element such that the second surface of the first optical element faces the second surface of the second optical element, where each of the first and the second optical elements is configured to move substantially perpendicular to the optical axis.

[0032] In one exemplary embodiment, the first optical element is configured to move synchronously with the second optical element and in opposite direction of the movement of the second optical element. In another exemplary embodiment, the first and the second optical elements are configured to move perpendicular to the optical axis by the same amount but in opposite directions.

[0033] In some embodiments with any of the above described systems, a z-height of at least 6 mm is achieved. In some embodiments with any of the above described systems, a field of view in the range 60 degrees to 75 degrees is achieved.

[0034] Another aspect of the disclosed embodiments relates to a method for manufacturing a miniature lens system that includes producing a structural platform comprising a frame and an arm, and molding a plurality of optical elements onto the frame of the structural platform subsequent to, and as a separate step from, producing the structural platform, the plurality of optical components comprising: a first varifocal lens, a first prism and a first base lens. In one exemplary embodiment, producing the structural platform comprises molding the arm onto the frame of the structural platform. In another exemplary embodiment, the above noted method further incudes connecting one or more actuators to the arm of the structural platform, the one or more actuators being coupled to one or more of the optical elements to allow movement of the one or more optical elements. In still another exemplary embodiment, the above noted method further comprises bonding a wafer-level optical component with a preformed lens element to the structural platform.

BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Fig. 1 depicts the dimensional tolerance versus component dimension for a precision injection molding regime that is implemented in accordance with the disclosed embodiments and other techniques.

[0036] Fig. 2 illustrates a sequence of operations that can be carried out to fabricate an integrated optical system in accordance with an exemplary embodiment.

[0037] Fig. 3 illustrates a top view of a fabricated molded structure in accordance with an exemplary embodiment.

[0038] Fig. 4 illustrates a set of operations that can be carried out to produce an integrated optical device in accordance with an exemplary embodiment.

[0039] Fig. 5 illustrates a set of operations that can be carried out to produce an integrated optical device in accordance with an exemplary embodiment.

[0040] Fig. 6 illustrates a set of operations that can be carried out in accordance with another exemplary embodiment to produce an integrated optical device.

[0041] Fig. 7 depicts an optical system in which the optical path is folded twice and varifocal lenses are located in between the folding optics in accordance with an exemplary embodiment.

[0042] Fig. 8 depicts an optical system with varifocal lenses located at the window, the optical path being folded before reaching the second varifocal lens and folded again before reaching the complementary metal-oxide semiconductor (CMOS) detector in accordance with an exemplary embodiment.

[0043] Fig. 9 depicts an optical system comprising a varifocal lens element integrated with a prism element and a CMOS detector placed vertically upright in accordance with an exemplary embodiment.

[0044] Fig. 10 is a ray diagram for an optical system in accordance with an exemplary embodiment.

[0045] Fig. 11 is a ray diagram for an optical system in accordance with another exemplary embodiment.

[0046] Fig. 12 illustrates a pair of varifocal lenses that include planar surfaces in accordance with an exemplary embodiment.

[0047] Fig. 13 illustrates a pair of varifocal lenses that include freeform surfaces in accordance with an exemplary embodiment.

[0048] Fig. 14 depicts the active area of an Alvarez-like lens in accordance with an exemplary embodiment.

[0049] Fig. 15 depicts an exemplary prism element with a freeform surface that can be utilized within at least one optical system of the disclosed embodiments.

[0050] Fig. 16 depicts an integrated lens platform and its associated components in accordance with an exemplary embodiment.

[0051] Fig. 17 illustrates a set of operations that can be carried out in accordance with an exemplary embodiment to produce a miniature lens system.

[0052] The disclosed embodiments relate to methods, devices, and fabrication processes that facilitate design and manufacturing of optical systems with improved alignment capabilities and reduced overall size, in addition to systems and methods for configuring components within an optical system.

[0053] To achieve movement of an optical component, such as a lens, along the optical axis (i.e., z-axis) or perpendicular to the optical axis (i.e., along the x- and y-axes), spring flexures can be utilized to allow the optical component to move laterally. The spring flexures can be simple beams or cascaded beam flexures.

[0054] In one approach, the lens element in an optical system can be fabricated through a molding process whereby a mold is created and liquid plastic resin is injected into the mold and hardened through UV or heat. The spring flexures can be fabricated separately, for example using micro fabrication processes. The lens element and the spring flexures can then be assembled. In this approach, however, alignment can be one major concern. For example, unlike typical spherical lens elements, free-form surfaces may not have rotational symmetry. Thus, besides the usual in-plane positioning issues, there is an additional rotational alignment between the lens element and the spring flexure structure. The actual step of assembly, whether through adhesives or other means, may also potentially disturb the alignment process.

[0055] The disclosed embodiments facilitate alignment of optical components in an optical system that can include optical components with spheric, aspheric, and/or free-form surfaces that may further move in any direction within the optical system. In some embodiments, monolithic integration of the lens element, spring flexures, and supporting

structures minimizes the number of post-assembly steps for integration and reduces possible misalignment issues.

[0056] Some of the disclosed embodiments rely on injection precision molding to fabricate optical systems that can include lenses and other optical components, as well as mechanical components such as flexible or rigid fixtures. Fig. 1 provides a comparison of dimensional tolerance versus component dimensions for a precision injection molding regime that is implemented in accordance with the disclosed embodiments. As illustrated in Fig. 1, precision injection molding enables the manufacture of smaller components with better tolerances compared to other techniques. As will be described in the sections that follow, multiple shots of injection molding can be sequentially introduced to produce integrated micro-optic devices in accordance with the techniques of the disclosed embodiments.

[0057] According to the disclosed embodiments, the lens and the flexures of an integrated optical device can be fabricated in a single step. This can be achieved in several ways. The lens element is essentially a refractive element with a certain surface profile. The required surface profile can be fabricated through casting from a mold. Fabrication of the lens together with the spring flexures can be accomplished by turning the additional spring flexures on the same mold as the lens. As such, when the plastic resin is injected into the mold, the resulting structure is a lens element with the spring flexures attached thereto. In this way, lens elements casted out separately can be assembled with the supporting structure. Other parts of the structure can be molded in the same step, as well. By way of example, and not by limitation, such other parts can include structures for assembly with other lens elements or structures for positioning and alignment.

[0058] In scenarios where a single-shot molding process is not feasible due to, for example, limitations in design flexibility, a multi-shot (e.g., two-shot, three-shot, four-shot, etc.) precision injection molding fabrication process can be used to fabricate the integrated optical system. For example, in a two-shot fabrication process, the first shot can cast out the spring flexures, and the second mold for the second shot can cast out the lens element integrated with the previously cast spring flexures. As the mold is removed, further fine-tuning on the dimensions can be done, if needed, through on-the-spot micromachining, such as with a precision computer numerical control (CNC) machine.

[0059] According to some embodiments, metal stamping can additionally, or

alternatively, used to mass-produce parts in a cost-efficient manner. In this case, the metal stamping mold can create the spring flexure skeleton structure that can be used to reinforce the subsequent molding step. The molding step can then cast out the lens element on the metal skeleton structure.

[0060] [0017] Besides molding the lens element on the metal skeleton structure, the lens elements can be molded in a separate process. This may be carried out to minimize the stress on the active lens area during the molding process. In such scenarios, the lens elements can be assembled onto the skeleton structure through a separate process such as ultrasonic welding or adhesives

[0061] According to some embodiments, micro-fabrication methods can additionally, or alternatively, be used to produce a chip-based mold. The chip or wafer produced using micro-fabrication techniques can include etched-out grooves that correspond to the locations of the spring flexures. The lens element can then be cast out separately and positioned on individual chips or wafers. Ultraviolet (UV) or heat-curable resin can then be poured to fill out the grooves together with the lens elements and subsequently cured. The resulting plastic piece is now a lens element with the spring flexures attached and aligned.

[0062] In another iteration, the above described fabricated integrated spring-flexure-lens can then be further assembled either with other components or another spring-flexure-lens assembly using one or more of the above-described techniques. As such, other structures can be incorporated into the molding process. Since other components also need to be assembled, some alignment structures can be molded as part of the overall structure.

[0063] In embodiments that require the movement of one or more optical components, an actuation mechanism is needed to move the lens. This actuation mechanism can also be incorporated into the mold design. For example, electromagnetic actuation can be implemented using a miniature coil of wire that is assembled on the integrated spring-flexure-lens. To this end, a groove can be designed to hold the miniature coil of wire on the integrated spring-flexure-lens.

[0064] As noted earlier, further refinements can be undertaken immediately after the plastic resin step through, for example, a precision micromachining that is performed on the cast plastic structure to further improve the tolerance of the components.

[0065] Fig. 2 illustrates a sequence of operations that can be carried out to fabricate an integrated optical system in accordance to an exemplary embodiment of the invention. The operations in Fig. 2 start with the creation of the elastic suspension mold. Next, the first shot of elastic suspension material is injected into the mold. Then, a second shot casts out the lens. Upon removal of the lens mold (in (d)) and removal of the integrated device (in (e)), the elastic suspension frame and the micro lens is obtained. Although the exemplary operations in Fig. 2 depict the fabrication process for a single-lens assembly with elastic suspension structures, it is understood that additional optical, mechanical (including alignment) structures can be integrated into the optical system through the existing or additional injection molding steps. Moreover, these additional structures can be rigid or elastic.

[0066] Fig. 3 illustrates a top view of a molded structure fabricated in accordance with an exemplary embodiment of the invention. The structure that is illustrated in Fig. 3 includes a supporting structure, a lens element, a holder for the lens actuator and elastic (e.g., spring) fixtures that allow the lens to be moved in the up/down direction indicated by the arrow. While the exemplary structure of Fig. 3 only shows movement of the lens in a single direction, it is understood that movement of the lens in three dimensions can be enabled. For example, additional elastic fixtures and appropriate actuation mechanisms can be included in the structure.

[0067] Further, alternate or additional optical components can be incorporated into the integrated systems that are fabricated in accordance with the disclosed embodiments. These components can include, but are not limited to, lenses, gratings, diffractive optical elements and the like. The disclosed embodiments provide for a sequence of manufacturing processes with tolerances in the region of 1 to 5 microns for an integrated platform incorporating elastic suspension, rigid frames, and optical components. The cost of manufacturing these components is estimated to be much lower than conventional MEMS micro fabrication.

[0068] Precision manufacturing technologies that are used for fabrication of the integrated systems in accordance with the disclosed embodiments can include injection molding, in-mold decoration, hot stamping, and/or insert molding. These processes allow mass manufacturing of integrated optical systems that can include a microlens on an elastic suspension platform. In some embodiments, the elastic suspension is made with a metal backbone that is fabricated using, for example, metal stamping followed by a polymer

molding (first shot). The metallic frames can enhance the elasticity of the suspension and robustness of the frame. In some embodiments, the elastic suspension is made without the metal backbone. The second shot can be a polymer material suitable for an optical lens. This component is then assembled into a larger structure making up an optical lens module. Multiple shots of injection molding process steps can be incorporated for multi-component integration.

[0069] Fig. 4 illustrates a set of operations 400 that can be carried out in accordance with an exemplary embodiment to produce an integrated optical device. At 402 a first mold is obtained that is structured to form an elastic suspension fixture. At 404, a first injection material is injected into the first mold. At 406 a second mold is placed in contact with the first mold and with the first injection material within the first mold. The second mold is structured to form an optical element. At 408, a second injection material is injected into the second mold. At 410 the second mold is removed and at 412 the first mold is removed to obtain the elastic suspension fixture with the optical element integrated thereto.

[0070] Fig. 5 and 6 illustrate two sets of operations 500 and 600, respectively, that can be carried out in accordance with other exemplary embodiments to produce an integrated optical device. In the exemplary embodiment of Fig. 5, at 502, a first mold is obtained that is structured to form an elastic suspension fixture and an optical element. At 504, a first injection material is injected into the first mold and, at 506, a second injection material is injected into the first mold. At 508, the first mold is removed to obtain the elastic suspension fixture with the optical element integrated thereto. In the exemplary operations 600 of Fig. 6, at 602, a mold is obtained that is structured to form an elastic suspension fixture and to house an optical element. At 604, the optical element is placed in the mold and, at 606, a first injection material is injected into the mold to form an elastic suspension fixture. At 608, the mold is removed to obtain the elastic suspension fixture with the optical element integrated thereto.

Zoom Lens Configuration

[0071] In applications with limited space (e.g., in a camera phone) the configuration of optical components significantly influences the size of the overall camera module that can be achieved. In such systems, the thickness (e.g., the thickness of the device in z-direction or "z-height") of the module is paramount. In order to deliver the smallest possible optical

configuration for a zoom lens system, several configurations are disclosed in this application.

[0072] As shown in Fig. 7, one embodiment features a light path-bending element, such as a prism 702 or a mirror, which is used to bend incoming rays 90 degrees, sending them through two varifocal lenses 704, 706 and another prism 708, which bends the optical path again for it to reach the detector (e.g., CMOS detector 710). In an exemplary embodiment, the fixed/base lens 714 is integrated with the prism 708, and the aperture 712 is placed in-between the two varifocal lenses 704, 706. Such a configuration offers the shortest z-height possible but suffers from limited field of view (FOV) and f-numbers. In this configuration, while it is possible to achieve a thin z-height of 6 mm, the FOV is limited to about 30°.

[0073] In order to increase the FOV, in some embodiments, at least one of the varifocal lenses may be located at the entrance of the optical system, as shown in Fig. 8. In the exemplary configuration of Fig. 8, a prism 802 is placed in-between the two varifocal lenses 804, 806 to bend the optical path 90 degrees and another prism 808 is used to bend the light an additional 90 degrees before reaching the detector (e.g., the CMOS detector 810). The aperture 812 is located between the prism 802 and the varifocal lens 806. The exemplary configuration of Fig, 8 allows a FOV of 60° to 75°. The z-height has to be increased to about 8 mm. Fig. 8 illustrates an exemplary configuration in which the detector is placed on the same side as the entrance of the optical system. However, it is understood that the detector can be placed on the side opposite to the entrance of the optical system (as, for example, illustrated in the configuration of Fig. 7). Placing the detector at the same side can minimize the z-height of the module since the increase in z-height is primarily due to the additional height of the lens and detector elements. Thus placing the detector 810 on the same side as the entrance window means that the z-height is increased only by the thicker of the two elements. However, since the optical path to reach the detector is relatively long, considering the need for the path to be folded before reaching the detector, the aperture and beam diameter is still relatively large in this configuration. An approach to shorten the optical path length to reach the detector can reduce the z-height even further.

[0074] To reduce the optical path length to reach the detector, in accordance with some embodiments, the detector is placed vertically upright and therefore closer to the lenses, as shown in Fig. 9. In the exemplary configuration of Fig. 9, a prism-like element 904 that includes a first varifocal lens integrated with a prism component is placed between the

window receiving the incident light and the second varifocal lens 906. Thus, the need for a second prism element is removed. The aperture 912 is located between the integrated varifocal lens and prism 904 and the second varifocal lens 906. The overall optical path length can be reduced from about 23 mm to about 18 mm. The reduction in optical path length allows a smaller aperture diameter along with smaller lens elements and therefore also smaller z-height. A z-height of approximately 6 mm can be obtained in this configuration. As another example, a z-height of between about 4-7 mm can be achieved. Without the varifocal lens integrated with the prism, the z-height will have to be increased slightly, to about 6.5 mm, to accommodate the gap between the varifocal lens and prism. In this configuration, a FOV in the range of 60°-75° can be achieved. Depending on the application, optical specification of the disclosed zoom lenses can be modified to meet the required size and form factor. For example, the z-height can be further reduced to meet specific implementation requirements.

[0075] Fig. 10 illustrates a ray diagram for a miniature lens configuration in accordance with an exemplary embodiment. The configuration of Fig. 10 provides a specific example of the lens system of Fig. 9 in which both varifocal lenses 1004 and 1006 are alvarez-like lenses. In addition, the various optical components in Fig. 10 are positioned to obtain the desired zoom capability. In particular, the first pair of Alvarez lenses 1004 is positioned to receive incident light from the entrance to the miniature lens system, and direct the light to the integrated prism. Although the exemplary diagram of Fig. 10 shows an integrated Alvarez lens-prism, it is understood that in some embodiments, the first Alvarez lens and the prism may be separate components. Referring back to Fig. 10, the light that enters the integrated prism is bent by 90 degrees before exiting the prism. The light is then received by the second Alvarez lens 1006, and subsequently travels through the Fixed/base lens group 1014 before reaching the detector 1010. In the example diagram of Fig. 10, by moving the two elements of the first Alvarez lenses 1004 perpendicular to the optical axis at opposite directions (e.g., one lens element is moved out and the other lens element is moved into the page), a negative optical power is produced. Further, in the exemplary diagram of Fig. 10, by moving the two elements of the second Alvarez lens 1006 perpendicular to the optical axis at opposite directions, a positive optical power is effectuated. The movement of the lens elements can be achieved using one or more actuators that are coupled to the lens elements. The exemplary configuration of Fig. 10 produces a miniature lens system with a small height, which makes this configuration particularly advantageous for implementation in devices with thin form factors, such as a cell phone or tablet.

[0076] Fig. 11 illustrates a ray diagram for a miniature lens configuration in accordance with another exemplary embodiment. The configuration of Fig. 11 provides yet another specific example of the lens system of Fig. 9 in which both varifocal lenses 1104 and 1106 are alvarez-like lenses. In addition, the various optical components in Fig. 11 are positioned to obtain the desired zoom capability. In particular, the first pair of Alvarez lenses 1104 is positioned to receive incident light from the entrance to the miniature lens system, and direct the light to the integrated prism. The light that enters the integrated prism is bent by 90 degrees before exiting the prism. The light is then received by the second Alvarez lens 1106, and subsequently travels through the Fixed/base lens group 1114 before reaching the detector 1110. In the example diagram of Fig. 11, by moving the two elements of the first Alvarez lenses 1104 perpendicular to the optical axis at opposite directions (e.g., one lens element is moved out and the other lens element is moved into the page), a positive optical power is produced. Further, in the exemplary diagram of Fig. 11, by moving the two elements of the second Alvarez lens 1106 perpendicular to the optical axis at opposite directions, a negative optical power is effectuated. The movement of the lens elements can be achieved using one or more actuators that are coupled to the lens elements. As is illustrated in Fig. 11 by the circled X and circled dot markings on the Alvarez lens elements, the movements of the lens elements are opposite to those illustrated in Fig. 10. By changing the optical power of the two pairs of Alvarez lenses, the focal length of optical system changed. In the exemplary diagram of Fig. 10, the lens system operates as a telescope with a long focal length.

[0077] Fig. 12 illustrates a lens configuration that includes two varifocal lenses in accordance with an exemplary embodiment. Each of the first varifocal lens 1202 and the second varifocal lens 1204 comprises two lens elements comprises two elements (Figure 12 illustrates elements 1 and 2 for the first lens 1202, and elements 3 and 4 for the second lens 1204). Each element is considered a thin plate, where each plate is characterized by two surfaces that are generally perpendicular to the optical axis. One surface is a plane surface and the other surface is a polynomial surface which is characterized by a function (e.g., a polynomial). The non-planar surface is designated as Alvarez surface in Fig. 12. For each of the lenses 1202 and 1204, by placing the two plates at a small distance from one another, and with the polynomial surfaces facing one another, an optical power is generated. By moving the two elements perpendicular to the optical axis at opposite directions synchronously, the optical power can be varied.

[0078] Fig. 13 illustrates a lens configuration that includes two varifocal lenses in accordance with another exemplary embodiment. The exemplary configuration of Fig. 13 includes a first varficoal lens 1302 and a second varifocal lens 1304 similar to those depicted in Fig. 12. However, instead of plane surfaces, the elements 1, 2, 3 and 4 in Fig. 13 each include a freeform surface that is shaped to correct aberrations in the optical system.

[0079] In each of the disclosed embodiments, the varifocal lenses can be, among other types, liquid crystals, liquid lenses, or Alvarez-like lenses. The varifocal lenses can also be made up of multiple lens elements, as in the case of Alvarez-like lenses. For each of the embodiments, it would not be feasible to configure conventional lenses for a small z-height module since a conventional lens moving along the optical axis would increase the z-height significantly. Further, to achieve a large FOV, at least one varifocal lens must be located at the entrance of the optical module.

Lens Active Area

[0080] The disclosed embodiments include additional improvements that further reduce the z-height of the optical module. In some embodiments that use Alvarez-like lenses, the Alvarez-like lenses are moved perpendicular to the optical path (instead of along the optical path) to perform tuning. Moreover, displacement of the Alvarez-like lenses perpendicular to the optical axis has a significant impact on the performance of the optical module. In particular, a larger displacement of the lens can result in a greater change of optical power. However, given that only a portion of the lens area is being utilized at a given position of the lenses (i.e., an "actual active area" of the lens), a larger displacement of the lenses also results in requiring a larger circular lens diameter to cover the active area. This scenario can be further illustrated with the aid of Fig. 14, in which the small circles represent two actual active areas of a varifocal lens at two different lens positions (i.e., displaced from one another perpendicular to the optical axis). While the diagram in Fig. 14 shows active areas of the same size for illustration purposes, the sizes of the actual active areas may not be the same. In the exemplary diagram of Fig. 14, the optical axis pointing in and out of the page. The large circle in Fig. 14 represents the circular area needed to encompass the active area of any single lens as the lens moves in x- and/or y-directions. The rectangular area represents the smaller single lens profile that is sufficient for the operation of the lens. The length of the rectangular area would typically represent the direction of motion.

[0081] In some embodiments, instead of a circular lens, a rectangular or oval-shaped lens that only covers the essential active area of the lenses is used. Such a lens in rectangular format is shown by the rectangular block in Fig. 14. In this manner, the actuation range can be increased without affecting the overall optical module size. Rotational alignment can be improved during assembly and fabrication.

Freeform Prism

[0082] According to some embodiments, the size of the optical system can be further reduced by combining the prism and varifocal lens elements. This is particularly relevant when Alvarez-like lenses are used. Using this technique, one of the sides of the prism can be molded with a freeform surface, as shown in Fig. 15, allowing additional gap space between the varifocal lens surfaces to be removed.

Integrated Platform

[0083] In moving lenses perpendicular to the optical axis, the mechanism has to be small, compact, and easily aligned and manufactured. Having the lens element integrated with a structural platform is a way of fulfilling these requirements. Fig. 16 shows an integrated platform in accordance with an exemplary embodiment. As shown in Fig. 16, the integrated platform comprises a frame that serves as a structural guide and an arm element that connects to an actuator element, such as a coil or magnet. The lens element can be directly molded or fabricated onto the frame with the correct orientation. A spring flexure element may or may not be incorporated with the integrated platform. In one embodiment, the platform frame and arm are molded in one step and the lens element molded after that. In another embodiment, the frame can be made of a lead frame metal structure. The lead frame can be metal- stamped, laser-cut, milled, etched, or molded. The arm element can be molded on the lead frame structure by an injection molding process, with the lens element molded onto the lead frame after the rest of the structures are completed.

[0084] In order for the molded lens to be aligned accurately, alignment structures can be incorporated onto the platform. Besides insert molding the lenses, a wafer-level optical

component with a preformed lens element can be bonded to the platform in a separate step. All of these processes are intended to allow the manufacturing process to be automated, keeping the overall structure compact and ensuring accurate alignment between structures and lens elements.

[0085] In actuating the integrated lens platform, incorporating a spring flexure element may or may not be necessary. A spring flexure primarily serves to provide a restoring force to the platform. This is necessary if the actuation mechanism is only capable of providing a force in a single direction, as in the case with a voice-coil actuator with a single-direction drive. A voice-coil actuator with a bidirectional drive can remove the need for a flexure-restoring element. Without the spring flexure element, the actuation range can be easily increased. By adding a position sensor on the system, the position of the lens platform can be well determined through a closed-loop control.

[0086] In some embodiments, the actuation requirement is simplified when two or more lenses are designed to move with the same displacement and direction. In this way, instead of having individual actuators for each lens element, one actuator is used to move two or more lenses. A mechanical structure can be designed to link the multiple lenses together. The structure is then actuated by an actuator.

Zoom and Focus Decouple Operation

[0087] Focusing and zoom are two operations that the optical system has to be able to perform. Regardless of the configuration that is used, the first varifocal lens element can be used for focusing purposes when the second varifocal lens is kept constant at a particular optical power. Operation in such a manner can be very elegant given the cost of more complex electronics and more constraints in terms of the optical optimization that has to be performed on the optical system.

[0088] To simplify the operation of the system, in some embodiments, the zoom and focusing operations are decoupled. Zoom is delivered through the tuning of the two varifocal lenses. Focusing can be performed through moving the base lens system along the optical axis. This simplifies the image optimization process and controls. In such embodiments, an actuator group actuates the varifocal lenses as a group. Focusing can be achieved through either moving the base lens group along the optical axis or a tunable lens element or elements in the base lens group. Suitable elements are optical lenses that can change their optical power, such as liquid lenses, liquid crystals, MEMS-based lenses, Alvarez-like lenses, and piezo-based lenses.

[0089] Fig. 17 illustrates a set of operations 1700 that can be carried out in accordance with an exemplary embodiment to produce a miniature lens system. At 1702, a structural platform comprising a frame and an arm is produced. At 1704, a plurality of optical elements are molded onto the frame of the structural platform subsequent to, and as a separate step from, producing the structural platform. The plurality of optical components comprising: a first varifocal lens, a first prism and a first base lens. In one exemplary embodiment, producing the structural platform comprises molding the arm onto the frame of the structural platform. In another exemplary embodiment, the above noted method further includes connecting one or more actuators to the arm of the structural platform. The one or more actuators are coupled to one or more of the optical elements to allow movement of the one or more optical elements. In yet another exemplary embodiment, the above method further includes bonding a wafer-level optical component with a preformed lens element to the structural platform.

[0090] It is understood that the operations that are described in the present application are presented in a particular sequential order in order to facilitate understanding of the underlying concepts. It is also understood, however, that such operations may be conducted in a different sequential order, and further, that additional or fewer steps may be used to carry out the various disclosed operations.

[0091] The foregoing description of embodiments has been presented for purposes of illustration and description. The foregoing description is not intended to be exhaustive or to limit embodiments of the present invention to the precise form disclosed, and modifications and variations are possible in light of the above teachings or may be acquired from practice of various embodiments. The embodiments discussed herein were chosen and described in order to explain the principles and the nature of various embodiments and their practical application to enable one skilled in the art to utilize the present invention in various embodiments and with various modifications as are suited to the particular use contemplated. The features of the embodiments described herein may be combined in all possible combinations of methods, apparatus, modules, systems, and articles of manufacture.