PATENT DOCUMENT

Publication Number: US-11105963-B1
Application Number: US-201715454195-A
Country: US
Kind Code: B1

Title: Optical systems with adjustable lenses

Abstract:
Optical systems may have tunable lenses with focal lengths that are adjusted by control circuitry. A display may produce image light that is received by a tunable lens. The display may be transparent so that light from objects can pass through the display and be received by the tunable lens. The tunable lens may include a birefringent lens element and a polarization rotator and may receive light that has been linearly polarized by passing through a linear polarizer. The polarization rotator may be operable in a first state in which the polarization of light passing through the polarization rotator is not rotated and a second state in which the polarization of light passing through the polarization rotator is rotated by 90°. The birefringent lens element may be formed from a cured liquid crystal polymer or other polymer and may have a liquid crystal additive to enhance birefringence.

Claims:
What is claimed is: 
     
       1. A system, comprising:
 a display having an array of pixels that creates images; 
 a birefringent polymer lens; 
 a polarization rotator, wherein light from the images passes through the polarization rotator and the birefringent polymer lens in that order; and 
 control circuitry that places the polarization rotator alternately in first and second states, wherein the light passes through the polarization rotator without rotation when the polarization rotator is in the first state and wherein the light passes through the polarization rotator with a 90° polarization rotation when the polarization rotator is in the second state, wherein the polarization rotator comprises a liquid crystal polarization rotator, wherein the birefringent polymer lens comprises liquid crystal material in a cured polymer, wherein the birefringent polymer lens comprises one of a plurality of birefringent polymer lenses, wherein the polarization rotator comprises one of a plurality of polarization rotators, and wherein the system includes a plurality of stacked tunable lenses each of which includes a respective one of the plurality of birefringent polymer lenses and each of which includes a respective one of the plurality of polarization rotators. 
 
     
     
       2. The system defined in  claim 1  wherein the polarization rotator comprises a twisted nematic liquid crystal polarization rotator. 
     
     
       3. The system defined in  claim 1  wherein the display comprises a transparent display and wherein light from an external object passes through the display and through the polarization rotator. 
     
     
       4. The system defined in  claim 1  further comprising a linear polarizer that linearly polarizes light entering the polarization rotator. 
     
     
       5. The system defined in  claim 1  wherein the birefringent polymer lens comprises first and second liquid crystal alignment layers. 
     
     
       6. The system defined in  claim 5  wherein the liquid crystal material in the cured polymer is interposed between the first and second liquid crystal alignment layers. 
     
     
       7. The system defined in  claim 1 , wherein the polarization rotator is interposed between the display and the birefringent polymer lens. 
     
     
       8. A tunable lens, comprising:
 a birefringent lens element; 
 a liquid crystal polarization rotator; 
 a linear polarizer that polarizes light entering the liquid crystal polarization rotator to produce light with a linear polarization, wherein the liquid crystal polarization rotator is operable in a first state in which the linear polarization of the light is not rotated by the liquid crystal polarization rotator and the birefringent lens element has a first focal length and a second state in which the linear polarization of the light is rotated by the liquid crystal polarization rotator and the birefringent lens element has a second focal length that is different than the first focal length; and 
 a polymer layer on the birefringent lens element, wherein the birefringent lens element is characterized by an ordinary index of refraction and an extraordinary index of refraction, and wherein the polymer layer has an index of refraction equal to the ordinary index of refraction. 
 
     
     
       9. The tunable lens defined in  claim 8  wherein the liquid crystal polarization rotator comprises a twisted nematic polarization rotator. 
     
     
       10. The tunable lens defined in  claim 8  wherein the birefringent lens element comprises a polished birefringent crystal. 
     
     
       11. A system, comprising:
 control circuitry; 
 a display coupled to the control circuitry that produces image light; and 
 a plurality of stacked tunable lenses that receive the image light, wherein each of the tunable lenses has a respective tunable focal length, wherein each of the stacked tunable lenses comprises a birefringent polymer lens element and a polarization rotator, wherein the control circuitry is configured to control the polarization rotator of each tunable lens to select an overall focal length for the plurality of stacked tunable lenses, and wherein the control circuitry is configured to repeatedly switch the overall focal length in synchronization with images being displayed on the display. 
 
     
     
       12. The system defined in  claim 11  wherein the polarization rotator comprises first and second transparent electrodes and a layer of liquid crystal material interposed between the first and second transparent electrodes and wherein the birefringent polymer lens elements each include a pair of liquid crystal alignment layers. 
     
     
       13. The system defined in  claim 11  wherein the birefringent polymer lens elements each include a plurality of ring-shaped electrodes.

Description:
This application is a continuation of U.S. patent application Ser. No. 15/381,882, filed Dec. 16, 2016, and U.S. provisional patent application No. 62/305,811, filed Mar. 9, 2016, which are hereby incorporated by reference herein in their entireties. 
    
    
     BACKGROUND 
     This relates generally to optical systems and, more particularly, to optical systems with adjustable lenses. 
     Cameras, display projectors, and other optical systems have lenses. It may sometimes be desirable to adjust a lens. For example, it may be desirable to adjust the focal length of a zoom lens or it may be desirable to focus a lens. Many optical systems are provided with manually adjustable lens mounts that allow lens adjustments such as focal length adjustments to be made. Motors and other electrically controllable elements may also be used in making lens adjustments. 
     Optical systems with adjustable lenses such as these may be bulky and may respond more slowly than desired to control commands. It would therefore be desirable to be able to provide improved optical systems with adjustable lenses such as compact electrically adjustable lenses. 
     SUMMARY 
     Optical systems may have adjustable lenses. The adjustable lenses may have focal lengths that are adjusted by control circuitry. Adjustable lenses may be used in adjusting magnification and focus in optical systems, may be used in optical systems with displays, and may be used in other optical systems. 
     A display in an optical system may produce images. The display may be transparent so that light from external objects can pass through the display. Light from images on the display and external objects can pass through an adjustable lens before reaching a viewer. The adjustable lens may be configured to exhibit different focal lengths. 
     The adjustable lens may include a birefringent lens element and a polarization rotator. Light received by the polarization rotator may be passed through a linear polarizer before being received by the polarization rotator. The polarization rotator may be operable in a first state in which the polarization of light passing through the polarization rotator is not rotated by the polarization rotator and a second state in which the polarization of light passing through the polarization rotator is rotated by 90° before reaching the birefringent lens element. The birefringent lens element may be formed from a liquid crystal polymer or other polymer having a liquid crystal additive to enhance birefringence or may be formed from a polished birefringent crystal. 
     Tunable lenses may be formed from a stack of multiple tunable focal length lenses. Polymer layers may be formed over lenses and may have indices of refraction that are selected to adjust the optical properties of the lenses. In polymer liquid crystal lenses, alignment layers or electrodes may be used to align liquid crystal material in desired orientations during polymer curing. 
     The polarization rotator may be a liquid crystal polarization rotator such as a twisted nematic (TN) liquid crystal polarization rotator. Control circuitry in the optical system can adjust polarization rotators and therefore lens focal length using control signals while creating synchronized images on a display. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a diagram of an illustrative optical system having a tunable lens in accordance with an embodiment. 
         FIG. 2  is perspective view of an illustrative tunable lens having a polarization rotator and a birefringent lens in accordance with an embodiment. 
         FIG. 3  is a cross-sectional side view of an illustrative tunable liquid crystal lens in accordance with an embodiment. 
         FIG. 4  is a cross-sectional side view of an illustrative lens having a stack of two tunable lenses in accordance with an embodiment. 
         FIG. 5  is a diagram showing operations and structures associated with forming a liquid crystal lens in accordance with an embodiment. 
         FIG. 6  is a cross-sectional side view of an illustrative liquid crystal lens with ring-shaped concentric electrodes for applying electric fields to liquid crystal material in the lens in accordance with an embodiment. 
         FIG. 7  is a top view of an illustrative liquid crystal lens in accordance with an embodiment. 
         FIG. 8  is a cross-sectional side view of an illustrative tunable birefringent lens formed from a polished birefringent material in accordance with an embodiment. 
     
    
    
     DETAILED DESCRIPTION 
     An illustrative optical system of the type that may be provided with tunable optical structures is shown in  FIG. 1 . As shown in  FIG. 1 , optical system  10  may include a tunable lens such as adjustable lens  14 . Lens  14  may include one or more lens elements (lenses) and may be adjusted electrically based on control signals received from control circuitry  12 . Control circuitry  12  may include storage and processing circuitry for supporting the operation of system  10 . The storage and processing circuitry may include storage such as hard disk drive storage, nonvolatile memory (e.g., flash memory or other electrically-programmable-read-only memory configured to form a solid state drive), volatile memory (e.g., static or dynamic random-access-memory), etc. Processing circuitry in control circuitry  12  may be used to control the operation of system  10 . The processing circuitry may be based on one or more microprocessors, microcontrollers, digital signal processors, baseband processors, power management units, audio chips, application specific integrated circuits, etc. System  10  may form all or part of an electronic device such as a camera, a projector, a display (e.g., a head mounted display), an embedded system such as a system in an automobile, airplane, or other vehicle, a cellular telephone, a computer, or other electronic equipment. For example, system  10  may be a system that displays images to a user such as user  20 . 
     To control the operation of system  10 , system  10  may be provided with input-output devices  28 . Input-output devices  28  be used to allow data to be supplied to system  10  and to allow data to be provided from system  10  to external devices. Input-output devices  28  may include buttons, joysticks, scrolling wheels, touch pads, key pads, keyboards, microphones, speakers, tone generators, vibrators, cameras, sensors, light-emitting diodes and other status indicators, data ports, etc. A user can control the operation of system  10  by supplying commands through input-output devices  28  and may receive status information and other output from system  10  using the output resources of input-output devices  28 . 
     System  10  may include one or more displays such as display  16 . Display  16  may be a liquid crystal display, an organic light-emitting diode display, a display formed from discrete light-emitting diode dies, or a display formed using other types of display technology. Display  16  may include an array of pixels for displaying images for user  20  such as image  18 . User  22  may view image  18  in direction  22  through lens  14 . Due to the presence of lens  14 , a virtual image such as virtual image  24  that corresponds to image  18  on display  16  may be viewed by user  22 . In the illustrative arrangement of  FIG. 1 , lens  14  is located at a distance D from user  20  that is larger than focal length f of lens  14  and is located at a distance d from display  16  that is less than focal length f, so virtual image  24  is magnified, but other configurations may be used, if desired. Display  16  may be opaque or may be transparent (e.g., display pixels may be formed on transparent substrates) so that real-life objects such as illustrative object  26  (e.g., a building, road, household object, or other object) may be viewed by user  20  through display  16  in addition to the images produced by display  16 . 
     The properties of lens  14  may be adjusted to adjust the appearance of virtual image  24 . For example, the focal length of lens  14  may be adjusted. In systems such as head-up displays (e.g., augmented reality or virtual reality displays), the focal length of lens  14  may be adjusted to reduce or eliminate vergence-accommodation mismatch. Other types of systems may also use lens focal length adjustments. In general, an adjustable-focal-length lens such as lens  14  of  FIG. 1  may be used in any suitable optical system in which it is desired to change the focal length properties of a lens. The use of lens  14  in a system of the type shown in  FIG. 1  in which lens  14  is interposed between a display such as illustrative transparent display  16  and user  20  is merely illustrative. 
     Lens  14  may have optical components of the type shown in  FIG. 2 . In particular, lens  14  may have a polarization rotator such as polarization rotator  14 A and a birefringent lens element such as birefringent lens  14 B. Optical system  10  may have a linear polarizer such as polarizer  30 . Polarizer  30  may polarize light from display  16  and/or light from objects in the user&#39;s environment such as object  26 . With one illustrative configuration, linear polarizer  30  is formed as the uppermost layer in display  16 . In general, linear polarizer  30  may be associated with any suitable structure in optical system  10  and need not be incorporated into a display. 
     Control circuitry  12  may adjust the polarization rotation properties of polarization rotator  14 A so that lens  14  exhibits either a first focal length fo or a second focal length fe&lt;fo. This adjusts the position at which light  32  is focused in the example of  FIG. 2 . In the  FIG. 2  example, birefringent lens  14 B has an ordinary index of refraction no that is aligned with dimension Y and an extraordinary index of refraction ne that is aligned with dimension X. Linearly polarized light  32  that is being received by rotator  14 A has an electric field that is aligned with dimension X. After passing through rotator  14 A, light  32  passes through adjustable lens  14  and is focused at point Pe or Po. 
     Polarization rotator  14 A has two different states. When control circuitry  12  places polarization rotator  14 A in its first state, polarization rotator  14 A will not rotate the polarization of light  32  (i.e., electric field E of light  32  will remain aligned with dimension X). In this situation, light  32  will experience an index of refraction of ne when passing through lens  14 B and the focal length of lens  14 B will be fe. Light  32  will therefore focus at point Pe. When control circuitry  12  places polarization rotator  14 A in its second state, polarization rotator  14 A will rotate the polarization of light  32  by 90° about axis Z (i.e., electric field E of light  32  will rotate out of alignment with dimension X and into alignment with dimension Y). In this situation, light  32  will experience an index of refraction of no when passing through lens  14 B and the focal length of lens  14 B will be fo. Light  32  will therefore focus at point Po. 
     Lens structures such as polarization rotator  14 A and birefringent lens element  14 B may be stacked on top of each other and may, if desired, be stacked in groups (i.e., lens  14  may be formed from multiple pairs of polarization rotators and birefringent lenses). In this way, the overall properties of lens  14  may be altered for different applications (e.g., the focal length of lens  14  may be shortened by stacking additional lenses). Stacked lens systems may also exhibit additional tuning states. For example, in a stacked lens system having a first tunable lens with two focal lengths and a second tunable lens with two focal lengths, the stacked lens system may exhibit four selectable focal lengths. 
     Polarization rotator  14 A may be formed from a liquid crystal polarization rotator structure or other suitable polarization rotator device. Birefringent lens  14 B may be formed from a birefringent crystal (e.g., calcite), may be formed from a birefringent liquid crystal lens, or may be formed from any other suitable birefringent lens structure. 
     As shown in the illustrative configuration of  FIG. 3 , polarization rotator  14 A may be formed from a liquid crystal polarization rotator such as a twisted nematic liquid crystal polarization rotator and birefringent lens  14 B may be formed from a liquid crystal lens structure. 
     In the example of  FIG. 3 , lens  14  has clear substrates such as substrates  34  and  46 . Substrates  34  and  36  may be formed from transparent materials such as clear glass or plastic. Transparent electrodes such as electrodes  36  and  44  may be formed from a transparent conductive material such as indium tin oxide and may receive electrical signals from control circuitry  12  to control the electric field across liquid crystal layer  40 . Electrode  36  may be formed on the surface of substrate  34  that faces liquid crystal layer  40 . Electrode  44  may be formed on the surface of substrate  46  that faces liquid crystal layer  40 . Liquid crystal alignment layers such as layers  38  and  42  may be formed on electrodes  36  and  44 . Layer  38  may be interposed between electrode  36  and layer  40 . Layer  42  may be interposed between electrode  44  and layer  40 . 
     Alignment layers  38  and  42  may be formed from polyimide or other suitable material that has been processed to form surfaces that help align the liquid crystals of layer  40  in a desired direction. With one suitable arrangement, layers  38  and  42  may be formed from photosensitive polymer (e.g., polyimide) that is exposed to linearly polarized ultraviolet light during curing. Other processes may be used for forming liquid crystal alignment layers for polarization rotator  14 A, if desired. 
     When liquid crystal layer  40  is placed between alignment layers  38  and  42 , the liquid crystals of layer  40  will be aligned in an orientation determined by the properties of alignment layers  38  and  42 . In the absence of an applied electric field across electrodes  36  and  44 , the liquid crystals of layer  40  will not be rotated away from their default alignment and light  32  that passes through polarization rotator  14 A will be emitted as light  32 - 2  having a polarization direction (electric field orientation) aligned with axis X (as an example). Light  32 - 2  will experience index of refraction ne when passing through birefringent lens  14 B. When an electric field is applied across electrodes  36  and  44  by control circuitry  12 , polarization rotator  14 A will rotate the polarization of light  32 . In particular, the liquid crystals of layer  40  will be rotated in response to the electric field so that layer  40  will, in turn, rotate the polarization of light  32  by 90° into alignment with axis Y (i.e., light  32  will be emitted as light  32 - 1  having a polarization aligned with axis Y). Light  32 - 1  will experience index of refraction no when passing through birefringent lens  14 B. Accordingly, lens  14 B and therefore lens  14  will exhibit different focal lengths depending on the setting of polarization rotator  14 B. 
     Lens  14 B of  FIG. 3  may be formed from a birefringent material such as an ultraviolet-light-curable liquid crystal polymer with an optional liquid crystal additive to enhance birefringence. The liquid crystal polymer may initially be dispensed in an uncured liquid monomer state and may fill a lens-shaped cavity between layer  54  and substrate layer  48 . Layers  48  and  54  may be clear layers formed from glass, polymer, or other clear material. For example, layer  54  may be formed from polymer. Alignment layers may be formed on the inner surfaces of the lens cavity. For example, alignment layer  52  may be formed on the lower surface of layer  54  and alignment layer  48  may be formed on the upper layer of substrate  46 . Alignment layers  52  may be formed by exposing photosensitive polymer such as a photosensitive polyimide to linearly polarized ultraviolet light during curing of the polyimide from a liquid polymer precursor or may be formed using other suitable alignment layer formation techniques. The presence of alignment layers  52  and  48  aligns the liquid crystal material of lens layer  50  in a desired direction and thereby gives rise to a desired birefringence (differing indices no and ne) in layer  50 . Ultraviolet light may be applied to layer  50  to cure and thereby solidify layer  50  (i.e., to convert layer  50  from its liquid monomer form into a solid polymer birefringent material). 
     The index of layer  54  and the birefringent properties of layer  50  may be selected to provide lens  14 B with desired optical characteristics. With one suitable arrangement, layer  50  may be formed from an ultraviolet-light-cured polymer such as RM257 (e.g., a liquid crystal polymer) and layer  54  may be formed from a polymer (e.g., an ultraviolet-light-cured polymer) such as polymethylmethacrylate (PMMA). In a configuration in which the index of refraction of layer  54  is equal to ordinary index no of layer  50 , lens  14 B will exhibit a focal length of infinity (when the polarization of light  32  is aligned with axis Y) and a finite focal length when the polarization of light  32  is aligned with axis X). If the index of refraction of layer  54  is greater than ordinary index no of layer  50 , lens  14  will, depending on the polarization of light exiting rotator  14 A, have a first focal length that is negative (lens  14 B will act as a concave lens) or will have a second focal length that is either positive or negative. If the index of refraction of layer  54  is less than no, lens  14 B will act as a convex lens with two focal lengths (depending on the polarization of light from rotator  14 A). 
     In the example of  FIG. 3 , substrate  46  serves both as a substrate for alignment layer  44  (and electrode  44 ) and as a substrate for alignment layer  48 . If desired, multiple substrate layers may be used to form layer  46  (e.g., multiple layers of glass and/or plastic). 
     The thickness of liquid crystal layer  40  in polarization rotator  14 A may be 1-10 microns, less than 50 microns, less than 20 microns, less than 5 microns, more than 1 micron, or other suitable thickness. When the thickness of liquid crystal layer is sufficiently thin, the tuning speed of rotator  14 B may be high (e.g., 5 ms, less than 10 ms, more than 1 ms, or other suitable amount). 
     As shown in  FIG. 4 , lens  14  may include multiple stacked tunable lenses. In the  FIG. 4  example, lens  14  includes first tunable lens  14 - 1  with polarization rotator  14 A- 1  and birefringent lens  14 B- 1  and second tunable lens  14 - 2  with polarization rotator  14 A- 2  and birefringent lens  14 B- 2 . In general, adjustable focal length lens  14  may include any suitable number of stacked adjustable lenses (one or more, two or more, three or more, etc.). In configurations with more stacked lenses, lens  14  can be adjusted to produce correspondingly larger numbers of focal lengths. For example in a two-lens stacked lens arrangement of the type shown in  FIG. 4 , lens  14 - 1  may be adjusted to produce focal length fa or focal length fb and lens  14 - 2  may be adjusted to produce focal length fc or fd. By cycling through different combinations of focal length (e.g., fa/fc, fa/fd, fb/fc, and fb/fd), lens  14  may exhibit four different focal lengths. 
     The ability to switch the polarization rotators of lens  14  at relatively high speeds (e.g., on the order of kHz) may allow lenses such as stacked lens  14  of  FIG. 4  to exhibit each of its different focal lengths in rapid succession. The images produced by display  16  (e.g., image frames) may be synchronized with these focal length changes, so that different images may be rendered by system  10  at different apparent distances from user  20  while minimizing or eliminating vergence accommodation mismatch. 
     Illustrative operations associated with forming birefringent liquid crystal lenses are shown in  FIG. 5 . Initially, a liquid ultraviolet-light-curable polymer for forming layer  54  may be deposited over mold  56 . Mold  56  may have lens-shaped protrusions. The liquid polymer of layer  54  may be cured by application of ultraviolet light  58  or may be cured using other curing techniques (catalyst, elevated temperature, room temperature curing, etc.). 
     After curing the polymer of layer  54  to solidify layer  54 , layer  54  may be removed from mold  56 . 
     Layer  54  and associated substrate layer  46  may then be coated with alignment layers  52  and  48 , respectively and may be sandwiched together to form a lens cavity that receives layer  50  (e.g., an ultraviolet-light-curable liquid polymer such as a liquid crystal polymer with an optional liquid crystal additive for enhancing birefringence). While the liquid crystals of layer  50  are being aligned by alignment layers  48  and  52 , the polymer material of layer  50  may be cured. For example, ultraviolet light  58  may be applied to layer  50  to cure layer  50  and thereby lock the birefringence of layer  50  in place. Lens  14 B may then be peeled away from substrate  46  (or may be left in place on substrate  46 ) and may be assembled with rotator  14 A to form a tunable lens. 
       FIG. 6  shows how lens  14 B may be formed by using patterned electrodes to rotate the liquid crystals of layer  50  during polymer curing. As shown in  FIG. 6 , lens  14 B may have a curable birefringent layer such as layer  50  that is formed between transparent substrates  62  and  66  (e.g., glass or plastic layers). Transparent electrode  64  (e.g., an indium tin oxide layer) may be formed on the surface of substrate  66  that faces layer  50 . A set of patterned electrodes  60  may be formed on the surface of substrate  62  that faces layer  50 . Layer  64  may be a blanket film that covers the surface of substrate  66 . Electrodes  60  may form a series of concentric rings such as illustrative rings  60 - 1 ,  60 - 2 , and  60 - 3 . There may be any suitable number of rings in electrodes  60  (e.g., five or more, ten or more, twenty or more, etc.). Each ring-shaped electrode may receive a different respective voltage (see, e.g., voltages V 0 , V 1 , and V 2  in the example of  FIG. 6 ) and may therefore rotate the liquid crystals in a respective underlying portion of layer  50  by a correspondingly different amount. By appropriate selection of the voltages of the ring-shape electrodes, the index of refraction of layer  50  may be progressively varied as a function of radial distance R from center CNT of lens  14 B, thereby providing lens  14 B with a desired index of refraction profile and focal length. Birefringence may be imparted to lens  14 B using an asymmetric configuration for electrodes  60 , using alignment layers, etc. The polymer material of layer  50  may be cured by application of ultraviolet light to layer  50  while the voltages are applied to electrodes  60 . After layer  50  has been cured in this way, the voltages on electrodes  60  may be removed. A top view of illustrative electrodes  60 - 1 ,  60 - 2 , and  60 - 3  of  FIG. 6  is shown in  FIG. 7 . 
     If desired, lens  14 B may be formed from a polished solid birefringent material such as calcite or other birefringent crystal. This type of arrangement is shown in  FIG. 8 . As shown in  FIG. 8 , lens  14  may include polished birefringent crystal  68  having a desired shape for forming lens  14 B and may include polarization rotator  14 A. Polarization rotator  14 A may be, for example, a twisted nematic liquid crystal polarization rotator of the type described in connection with  FIG. 3  or may be any other type of polarization rotator. If desired, an optional layer of material such as layer  70  may be applied to the upper surface of lens element  68 . As described in connection with layer  54  of  FIG. 3 , the index of refraction of layer  70  may be the same as the ordinary index of refraction no of lens element  68  or may be greater or less than index no. Lenses of the type shown in  FIG. 8  may be stacked with other adjustable lenses and may be incorporated into an optical system such as optical system  10  of  FIG. 1  or other suitable optical system, as described in connection with  FIG. 4 . 
     The foregoing is merely illustrative and various modifications can be made by those skilled in the art without departing from the scope and spirit of the described embodiments. The foregoing embodiments may be implemented individually or in any combination.

Metadata:
Filing Date: 20170309
Publication Date: 20210831
Grant Date: 20210831
Priority Date: 20160309
Inventors: CHEN, YUAN
WILBURN, BENNETT S.
CHEN, CHENG
SLOOTSKY, MICHAEL
WANG, SHUANG
GE, ZHIBING
Assignee: APPLE INC
CPC Classifications: [{"code": "G02B7/08", "inventive": false, "first": false, "tree": "[]"}, {"code": "G02B27/286", "inventive": false, "first": false, "tree": "[]"}, {"code": "G02F1/294", "inventive": true, "first": true, "tree": "[]"}, {"code": "G02F1/294", "inventive": true, "first": false, "tree": "[]"}, {"code": "G02B30/25", "inventive": true, "first": false, "tree": "[]"}, {"code": "G02B15/14", "inventive": true, "first": false, "tree": "[]"}, {"code": "G02B27/288", "inventive": true, "first": false, "tree": "[]"}, {"code": "G02B3/14", "inventive": true, "first": true, "tree": "[]"}, {"code": "G02B5/20", "inventive": true, "first": false, "tree": "[]"}, {"code": "G02B3/14", "inventive": true, "first": true, "tree": "[]"}, {"code": "G02F1/294", "inventive": true, "first": false, "tree": "[]"}, {"code": "G02B27/288", "inventive": true, "first": false, "tree": "[]"}, {"code": "G02B15/14", "inventive": true, "first": false, "tree": "[]"}, {"code": "G02B5/20", "inventive": true, "first": false, "tree": "[]"}, {"code": "G02B30/25", "inventive": true, "first": false, "tree": "[]"}]
Family ID: 77465185