Optical assembly including plenoptic microlens array

An optical assembly includes a solid spacing layer between a plenoptic microlens array (MLA) and a pixel-level MLA, avoiding the need for an air gap. Such an assembly, and systems and methods for manufacturing same, can yield improved reliability and efficiency of production, and can avoid many of the problems associated with prior art approaches. In at least one embodiment, the plenoptic MLA, the spacing layer, and the pixel-level MLA are created from optically transmissive polymer(s) deposited on the photosensor array and shaped using photolithographic techniques. Such an approach improves precision in placement and dimensions, and avoids other problems associated with conventional polymer-on-glass architectures. Further variations and techniques are described.

FIELD OF THE INVENTION

The present invention relates to an optical assembly including a plenoptic microlens array such as can be used in a light-field camera to capture directional information for light rays passing through the camera's optics.

BACKGROUND

Light-field cameras, which may also be referred to as plenoptic cameras, use a plenoptic microlens array (MLA), in combination with a photosensor array, to capture directional information of light rays passing through the camera's optics. Such directional information can be used for providing and implementing advanced display of and interaction with captured pictures, such as refocusing after capture. Such techniques are described, for example, in Ng et al., “Light Field Photography with a Hand-Held Plenoptic Camera”, Technical Report CSTR 2005-02, Stanford Computer Science, and in related U.S. Utility application Ser. No. 12/632,979, for “Light-field Data Acquisition Devices, and Methods of Using and Manufacturing Same,” filed Dec. 8, 2009, the disclosure of which is incorporated herein by reference.

Plenoptic microlens arrays are often manufactured using a polymer-on-glass approach, including a stamping or replication process wherein the plenoptic MLA is fabricated as a polymer attached to a transparent glass surface. Plenoptic MLAs can be constructed in such a manner using machines and processes available, for example, from Suss MicroOptics of Neuchatel, Switzerland. The polymer-on-glass MLA array is placed with the lens side down, such that incoming light passes through the glass and is then directed by the plenoptic MLA onto the surface of a photosensor array.

Referring now toFIG. 1A, there is shown an example of an assembly100for a light-field camera according to the prior art, wherein the plenoptic MLA102, including any number of individual microlenses116, is constructed using a polymer-on-glass approach, resulting in MLA102being fabricated on glass103. An air gap105has been introduced between plenoptic MLA102and photosensor array101of the device, to allow for light rays to be properly directed to correct locations on photosensor array101.

In general, existing techniques for manufacturing a light field sensor require that photosensor array101and plenoptic MLA102be fabricated as separate components. These components may be assembled using a mechanical separator that adds air gap105between the components. Such an assembly process can be expensive and cumbersome; furthermore, the resulting air gap105is a potential source of misalignment, unreliability, and/or reduced optical performance. It is desirable to avoid such separate fabrication of parts and later assembly using mechanical separation so as to improve manufacturing efficiency, and so that precision in placement of the lens components can be achieved.

In many image capture devices, a different type of microlens array, referred to herein as a pixel-level microlens array, is used to improve light capture performance and/or reduce crosstalk between neighboring pixels in a photosensor array101. Referring now toFIG. 1B, there is shown an example of an assembly150according to the prior art. Relative toFIG. 1A, this diagram is shown at much higher magnification. Microlenses206in pixel-level microlens array202direct incoming light104so as to maximize the amount of light that reaches each individual photosensor106, and to avoid losing light that would otherwise hit the areas between individual photosensors106. Such an arrangement is well known in the art, and may be included on many commercially available image sensors.

The plenoptic microlens array102depicted inFIG. 1Aand the pixel-level microlens array202depicted inFIG. 1Bserve completely different purposes. In general, these two types of microlens arrays are constructed to be of differing sizes and locations. For example, each microlens206of pixel-level microlens array202may be approximately2microns across, while each microlens116of the plenoptic microlens array102may be approximately20microns across. These measurements are merely examples. In general, pixel-level microlenses206may have a 1:1 relationship with photosensors106, while plenoptic microlenses116may have a 1:many relationship with photosensors106.

Referring now toFIG. 2, there is shown an optical assembly200including both a plenoptic MLA102and a pixel-level MLA202according to the prior art. Such an assembly200effectively combines the components depicted and described in connection withFIGS. 1A and 1B. Here, plenoptic MLA102directs incoming light104toward pixel-level MLA202. Microlenses206in pixel-level MLA202then further direct light toward individual photosensors106in photosensor array101. In the arrangement ofFIG. 2, air gap105is provided between plenoptic MLA102and pixel-level MLA202.

As described above, plenoptic MLA102ofFIG. 2can be constructed using a polymer-on-glass approach, wherein plenoptic MLA102is attached to glass surface103. For example, plenoptic MLA102may be formed using a mold that is stamped out using polymer and affixed to glass surface103. The resulting plano-convex microlens assembly is positioned in a “face-down” manner as shown inFIG. 2, with the convex lens surfaces facing away from the light source.

The inclusion of both a plenoptic MLA102and a pixel-level MLA202serves to further complicate the construction of the image capture apparatus. Existing techniques offer no reliable method for constructing an image capture apparatus that employs both a plenoptic MLA102and a pixel-level MLA202, without introducing an air gap105. Introduction of such an air gap105potentially introduces further complexity, cost, and potential for misalignment.

SUMMARY

According to various embodiments of the present invention, an improved system and method of manufacturing an optical assembly including a plenoptic microlens array are described. Further described is an improved optical assembly including a plenoptic microlens array, fabricated according to such an improved manufacturing method. The various systems, methods, and resulting optical assembly described herein yield improved reliability and efficiency of production, and avoid many of the problems associated with prior art approaches.

According to various embodiments of the present invention, an optical assembly including a plenoptic microlens array (MLA) is fabricated without the need to introduce an air gap between the plenoptic MLA and other components of the optical system. In at least one embodiment, the plenoptic MLA, along with a solid spacing layer, is manufactured in such a manner that it is integrated with the photosensor array. For example, in at least one embodiment, the plenoptic MLA is created from an optical polymer deposited on the photosensor array, and then shaped using photolithographic techniques. The use of the solid spacing layer avoids the need for an air gap between the plenoptic MLA and other components.

Such an approach improves precision in placement and dimensions, and avoids other problems associated with polymer-on-glass architectures. The use of a photolithographic process also allows the plenoptic microlens array to be positioned in a face-up manner, so as to improve optical performance. Misalignment and imprecision resulting from assembly can also be reduced or eliminated. In addition, the photolithographic approach allows for more precise alignment of the plenoptic microlens array relative to the photosensor array.

In at least one embodiment, the plenoptic MLA is constructed together with a pixel-level MLA, without the need for an air gap between the two MLA's. The plenoptic MLA, along with a solid spacing layer, are fabricated directly atop the pixel-level MLA. Such a technique provides the added functionality associated with a pixel-level MLA while avoiding problems associated with prior art approaches that involve the use of an air gap.

The present invention also provides additional advantages, as will be made apparent in the description provided herein.

DETAILED DESCRIPTION OF THE EMBODIMENTS

According to various embodiments of the present invention, optical assemblies are constructed that avoid the need for an air gap between a plenoptic microlens array (MLA) and other components. In at least one embodiment, a photolithographic process is used, wherein a spacing layer containing solid spacing material is introduced between the plenoptic MLA and other components, so as to avoid the need for an air gap.

For illustrative purposes, various configurations of optical assemblies including plenoptic MLA's are described herein. One skilled in the art will recognize that the particular configurations depicted herein are exemplary only, and that other configurations, arrangements, and manufacturing techniques can be implemented without departing from the essential characteristics of the claimed invention.

In at least one embodiment, the various optical assemblies described and depicted herein can be implemented as part of any suitable image capture device, such as a camera. For example, any of such optical assemblies can be implemented as part of a light-field camera such as described in Ng et al., and/or in related U.S. Utility application Ser. No. 12/632,979 for “Light-field Data Acquisition Devices, and Methods of Using and Manufacturing Same,” filed Dec. 8, 2009, the disclosure of which is incorporated herein by reference. Such a light-field camera can be designed to capture and store directional information for the light rays passing through the camera's optics. Such directional information can be used for providing and implementing advanced display of and interaction with captured pictures, such as refocusing after capture. One skilled in the art will recognize, however, that the techniques described herein can be applied to other types of devices and apparatuses, and are not necessarily limited to light-field cameras.

Referring now toFIG. 3, there is an optical assembly300including both a plenoptic MLA102and a pixel-level MLA202, wherein plenoptic MLA102is positioned “face-up”, i.e., with the convex lens surfaces facing toward the light source, according to one embodiment of the present invention. In at least one embodiment, such a configuration can provide improved optical performance. However, existing polymer-on-glass approaches can make such an arrangement difficult to achieve, because glass103may be too thick to allow proper and accurate positioning of the convex lens elements of plenoptic MLA102at the appropriate distance from pixel-level MLA202.

The approaches inFIGS. 2 and 3both involve separate construction of photosensor array101and plenoptic MLA102; the components are then assembled using a mechanical separator that adds air gap105between the components. As discussed above, the resulting air gap105can also be a source of misalignment, unreliability, and/or reduced optical performance.

Integration of Plenoptic MLA with Photosensor Array

According to various embodiments of the present invention, an optical assembly including plenoptic MLA102is fabricated without the need to introduce an air gap between plenoptic MLA102and other components of the optical system. Referring now toFIG. 4, there is shown a cross-sectional diagram depicting a detail of optical assembly400including both plenoptic MLA102and pixel-level MLA202, constructed according to an embodiment of the present invention. Plenoptic MLA102, along with layer401of spacing material, are manufactured in such a manner that they adjoin one another. Spacing layer401also adjoins pixel-level MLA202. Such an arrangement avoids the need for an air gap. For example, in at least one embodiment, plenoptic MLA102and spacing layer401are created from an optical polymer deposited or “spin-coated” on photosensor array101, and then shaped using photolithographic techniques. Plenoptic MLA102and spacing layer401may be created at the same time in a single process, or sequentially by first creating spacing layer401and then adding plenoptic MLA102. One method to create the profile for plenoptic MLA102is to use a gray-scale mask for photolithography. Once cured, spacing layer401and plenoptic MLA102are solid. One skilled in the art will recognize, however, that other techniques can be used to generate an optical assembly400as shown inFIG. 4.

In the example ofFIG. 4, the index of refraction of plenoptic MLA102(and spacing layer401) is lower than that of pixel-level MLA202. One skilled in the art will recognize, however, that different materials, such as polymers of varying types or other materials of varying refractive indices can be used for the various layers and components. As described herein, variations in the indexes of refractions of the materials can be exploited to achieve desired optical characteristics of the overall assembly400.

For example, referring now toFIG. 5, there is shown a cross-sectional diagram depicting a detail of an optical assembly500wherein the index of refraction of plenoptic MLA102(and spacing layer401) is higher than that of pixel-level MLA202. Again, in at least one embodiment, such an assembly500can be fabricated using photolithographic processes.

In the examples ofFIGS. 4 and 5, the shaping of the microlenses206in pixel-level MLA202is optimized to focus light on photosensors106based on the optical interface between pixel-level MLA202and spacing layer401. InFIG. 4, the index of refraction R1of plenoptic MLA102and spacing layer401is lower than the index of refraction R2of pixel-level MLA202. In this case, microlenses206in pixel-level MLA202have a convex shape. Conversely, inFIG. 5, the index of refraction R2of plenoptic MLA102and spacing layer401is higher than the index of refraction R1of pixel-level MLA202. In this case, microlenses206in pixel-level MLA202have a concave shape, so as to properly direct light rays onto photosensors106.

As can be seen from the example configurations shown inFIGS. 4 and 5, the techniques of the present invention avoid the need for mechanical spacing and an air gap, since spacing is accomplished via spacing layer401deposited, for example, as part of the photolithographic process. This arrangement results in improved precision in placement of the plenoptic MLA102.

In at least one embodiment, the techniques of the present invention provide improved horizontal and vertical alignment between plenoptic MLA102and other components such as pixel-level MLA202and photosensor array101, by using the precise alignment techniques used in lithographic manufacture. Such improvements in horizontal (x-y) alignment help ensure that microlenses116of plenoptic MLA102accurately direct light to appropriate locations along pixel-level MLA202. In at least one embodiment, plenoptic MLA102may be created in a manner such that each microlens116covers an integral number of pixels (for example, using a square layout with each plenoptic microlens116covering an area corresponding to 10×10 photosensors106in photosensor array101). The improved vertical (z) alignment ensures that proper focus is obtained.

In addition, the techniques of the present invention provide reduced error. Lithographic depositing of materials to generate the microlens structures has the potential to produce more precise optics than conventional polymer-on-glass assemblies.

The techniques of the present invention can provide improved reliability and alignment of components, and can reduce manufacturing costs by removing the need for mechanical separators to introduce an air gap. Furthermore, such techniques help to ensure that the plenoptic MLA102is constructed in such a manner that the optical performance of pixel-level MLA202is not unduly comprised.

Method of Manufacture

In at least one embodiment, the optical assemblies described herein are manufactured using stamping to deposit and shape an optical material directly onto photosensor array101. The optical material can be any suitable material, such as polymer that can be cured using ultraviolet light. The stamp forms the optical material into the desired shape, including, for example, the convex surfaces that will make up plenoptic MLA102. In at least one embodiment, the stamping can be performed using a stamp that is transparent or semi-transparent to ultraviolet light, allowing the polymer to be cured while the stamp is in place. Such a mechanism assures precise and accurate positioning of plenoptic MLA102with respect to other components.

Referring now toFIG. 12, there is shown a flow diagram depicting a method for fabricating an optical assembly including a pixel-level MLA202, spacing layer401, and plenoptic MLA102, according to an embodiment of the present invention. Referring also toFIG. 11, there is shown a cross-sectional diagram depicting a detail of an example of an optical assembly1100constructed according to the method ofFIG. 12.

One skilled in the art will recognize that the particular steps and sequence described and depicted herein are merely exemplary, and that the present invention can be practiced using other steps and sequences. One skilled in the art will recognize that the optical assemblies described herein can be constructed using any suitable material or combination of materials, and that the mention of particular materials and/or properties of such materials herein is merely intended to be exemplary, and is not intended to limit the scope of the invention to those particular materials/or properties of such materials. In particular, the example indexes of refraction depicted and described herein are merely exemplary.

The method begins1200. Pixel-level MLA202is created1201, using, in at least one embodiment, a material with a very high index of refraction, such as silicon nitride, with an index of refraction of approximately 2.05. In at least one embodiment, lenses206of pixel-level MLA202are made in a convex shape, and are positioned directly above photosensor array101. One skilled in the art will also recognize that the pixel-level MLA is a converging lens, and that a converging lens may be made in many shapes and complexities, and that the mention of particular shapes and/or orientations herein is merely intended to be exemplary, and is not intended to limit the scope of the invention. In at least one embodiment, lenses206of pixel-level MLA202are aligned with sensors106of photosensor array101.

Optionally, planarization layer1101is added1202on top of pixel-level MLA202. In at least one embodiment, planarization layer1101is formed using a material with a lower index of refraction than that of pixel-level MLA202, creating an optical interface between planarization layer1101and pixel-level MLA202. An example of a material that can be used for planarization layer1101is silicon dioxide, with an index of refraction of approximately 1.5.

In at least one embodiment, optical spacing layer401composed of spacing material is added1203, for example via deposition or spin coating, on top of planarization layer1101. Spacing layer401may be composed of any optically transmissive material, and may be applied in such a manner so that the thickness of layer401may be precisely controlled to match the optimal focal length of plenoptic MLA102, adjusted for the index of refraction of spacing layer401material. For example, in at least one embodiment, optically transmissive photoresist may be used to apply spacing layer401. Spacing layer401may be applied using spin-coating, deposition and/or any other suitable process. Preferably, such a process is optimized so as to ensure the addition of a very flat and evenly distributed layer.

Material for plenoptic MLA102is then added1204on top of optical spacing layer401. In at least one embodiment, plenoptic MLA102is added1204by depositing a layer of photoresist with a precisely controlled thickness. This layer of photoresist is developed into plenoptic MLA102using any suitable means, such as for example a grayscale mask and photolithographic process. In at least one embodiment, the optical properties of plenoptic MLA102are determined in order to provide optimal focus on the plane of pixel-level MLA202, taking into account all optical materials between plenoptic MLA102and pixel-level MLA202. In at least one embodiment, the layer of photoresist has an index of refraction in the range of 1.4-1.6. Plenoptic MLA102is shaped1212, for example by a stamping process. As described above, in an embodiment wherein the optical material used for plenoptic MLA202is a polymer that can be cured using ultraviolet light, the stamp is transparent or semi-transparent to ultraviolet light, allowing the polymer to be cured while the stamp is in place.

In at least one embodiment, spacing layer401and plenoptic MLA102are constructed from the same material and are deposited at the same time using, for example, a layer of photoresist and grayscale mask photolithography. The single layer is then shaped to form both spacing layer401and plenoptic MLA102, according to known photolithographic techniques. In such an embodiment, steps1203and1204can be combined into a single step wherein the material for both spacing layer401and plenoptic MLA102are deposited; in step1212, stamping is performed to form both spacing layer401and plenoptic MLA102.

In various embodiments, the various layers described and depicted herein, including pixel-level MLA202, planarization layer1101, spacing layer401, and/or plenoptic MLA102, may be manufactured using any method or process now known or later developed, including, for example, deposition, spin coating, any lithographic method, ion implantation, silicon doping, and/or diffusion.

Referring now toFIGS. 14A through 14C, there is shown a series of cross-sectional diagrams depicting an example of fabrication of a plenoptic MLA102and spacing layer401using a stamping method, according to an embodiment of the present invention. InFIG. 14A, lens material1402, such as a polymer or other suitable material, has been dispensed on photosensor array101. For clarity, pixel-level MLA202and other aspects have been omitted fromFIGS. 14A through 14C. As described above, such material1402can include, for example, a polymer, silicon nitride, photoresist, and/or any other suitable material. MLA stamp1401contains indentations1404for shaping material1402into microlenses for plenoptic MLA102. Standoffs1403are affixed to photosensor array101to ensure that stamp1401descends to an appropriate distance from photosensor array101but no closer. These standoffs1403may be used to set the height of spacing layer401. In at least one embodiment, standoffs1403are removable, so that they can be detached after the process is complete.

InFIG. 14B, MLA stamp1401has descended so that it forms material1402into the appropriate shape for plenoptic MLA102. In at least one embodiment, a curing process is now performed, for example by exposing material1402to ultraviolet light. In at least one embodiment, MLA stamp1401is constructed from a material that is optically transmissive with respect to the type of light used for curing, so that curing can take place while stamp1401is in the descended position. In at least one embodiment, standoffs1403are constructed to allow any excess material1402to escape through the sides.

InFIG. 14C, curing is complete and MLA stamp1401has been removed. Material1402has now formed into plenoptic MLA102. If desired, standoffs1403can now be removed, along with any excess material1402.

AlthoughFIGS. 14A through 14Cdepict fabrication of a plenoptic MLA102, a similar technique can also be used for fabrication of pixel-level MLA202and/or other layers of the optical assembly.

Variations

One skilled in the art will recognize that many variations are possible without departing from the essential characteristics of the present invention. The following is an exemplary set of such variations, and is not intended to be limiting in any way.

No Pixel-Level MLA

In at least one embodiment, pixel-level MLA202can be omitted. Photolithographic techniques can be used to deposit material for spacing layer401and plenoptic MLA102directly onto the surface of photosensor array101. Plenoptic MLA202directs light directly onto individual sensors106of photosensor array101.

Multiple Layers of Pixel-Level MLAs

Referring now toFIG. 6, there is shown is a cross-sectional diagram depicting a detail of an optical assembly600including plenoptic MLA102and a two-layer pixel-level MLA202, wherein optical assembly600is fabricated using a photolithographic process according to an embodiment of the present invention. Here, pixel-level MLA202is depicted as having two layers601A,601B, although any number of layers601of pixel-level MLA202can be provided. Such an approach can be useful when, for example, the difference in index of refraction between the material used for spacing layer401and the material used for the pixel-level MLA202is insufficient to obtain the desired degree of optical refraction in a single layer. Layers601of pixel-level MLAs202can have the same index of refraction as one another, or different indexes of refraction.

Pixel-Level MLA Formed Using GRIN

Referring now toFIG. 7, there is shown a cross-sectional diagram depicting a detail of an optical assembly700including plenoptic MLA102and pixel-level MLA202C, wherein pixel-level MLA202C is fabricated using a material having a gradient index of refraction (GRIN), according to an embodiment of the present invention. Such a material is characterized by variations in the index of refraction for different portions of the material. The use of gradient-index optics allows for a great degree of customizability in the optical characteristics of pixel-level MLA202C. In the example shown inFIG. 7, the optical material is deposited in such a manner that an area701of higher index of refraction R2is positioned above each photosensor106in photosensor array107. These areas701of higher index of refraction R2serve to direct light to photosensors106, in a similar manner to the microlenses206described in connection withFIG. 4and elsewhere herein. The gradient index may be created using any method now known or later developed. See, for example, R. S. Moore, U.S. Pat. No. 3,718,383, for “Plastic Optical Element Having Refractive Index Gradient”, issued Feb. 27, 1973.

Pixel-Level MLA Modified to Match Optical Properties of Plenoptic MLA

Referring now toFIG. 8, there is shown is a cross-sectional diagram depicting a detail of an optical assembly800including plenoptic MLA102and pixel-level MLA202D, wherein pixel-level MLA202D is fabricated in a manner that matches certain optical properties of plenoptic MLA102, according to an embodiment of the present invention. Specifically, pixel-level MLA202D is shaped to form a series of concave areas, or bowls801. In this example, bowls801are highly aligned (in X-Y) with individual microlenses116in plenoptic MLA102. Such an arrangement may be useful in situations where plenoptic MLA102has significant field curvature. The precise alignment allowed by lithographic techniques facilitate shaping of pixel-level MLA202D to match the field curvature of plenoptic MLA102, allowing for better focus and more efficient light capture.

Opaque Microstructures on Pixel-Level MLA

FIG. 9is a cross-sectional diagram depicting a detail of an optical assembly900including plenoptic MLA102and pixel-level MLA202, further including opaque microstructures901to block stray light from neighboring microlenses116in plenoptic MLA102, according to an embodiment of the present invention.

In general, it is optimal if light from one plenoptic microlens116does not overlap with light from a neighboring plenoptic microlens116. In practice, optical aberrations and diffraction often lead to some overlap. In at least one embodiment, this problem is addressed by adding optically opaque microstructures901at positions corresponding to the edges of plenoptic microlenses116; these areas are referred to as lens intersection zones.

Optical assembly900can be constructed using any suitable technique. Referring now toFIG. 13, there is shown a flow chart depicting a method of constructing an optical assembly900having opaque microstructures901as depicted in the example ofFIG. 9.

The method begins1300. Steps1201and1202are performed substantially as described above in connection withFIG. 12, so as to create1201pixel-level MLA202and add1202planarization layer1101. Then, an optically opaque material is deposited and etched1301, forming boundary microstructures901. In at least one embodiment, boundary microstructures901are generated using a binary photomask and dry etching. If needed, multiple iterations may be deposited to reach the desired height and/or shape. Microstructures901, which may also be referred to as baffles, can be constructed to be of any desired height, thickness, and/or shape.

In at least one embodiment, microstructures901are upright with respect to photosensor array107. In other embodiments, microstructures901may be positioned at angles that vary across the surface of photosensor array107, for example to match the designated chief ray angle at different positions on photosensor array107. Thus, different microstructures901can have different angles with respect to photosensor array107, so that they are all correctly oriented with respect to the apparent center of the light reaching photosensor array107from a particular plenoptic microlens116.

In various embodiments, boundary microstructures901can be included instead of or in addition to planarization layer1101depicted inFIG. 11. Accordingly, step1202, depicted inFIG. 12, can be included or omitted as appropriate.

Steps1203,1204, and1212are performed substantially as described in connection withFIG. 12, so as to add1203spacing layer,401, and add1204and shape1212the material for plenoptic MLA102. As described above, any suitable technique, such as grayscale photolithography or some other method, can be used to create plenoptic MLA102.

Referring now toFIG. 10, there is shown a cross-sectional diagram depicting a detail of an optical assembly1000including a plenoptic MLA102having multiple layers1001A,1001B, according to an embodiment of the present invention. In various embodiments, each layer1001can have the same index of refraction or different indexes of refraction. Such a plenoptic MLA102can be generated, for example, using successive lithographic steps.

A multi-layer plenoptic MLA102as shown inFIG. 10can be used, for example, when the index of refraction used for plenoptic MLA102is insufficient to direct the incoming light in the desired direction. Additionally, the use of multiple optical surfaces may improve the optical performance of plenoptic MLA202. Any number of layers can be included. Accordingly, such a layering technique may be expanded to create more advanced plenoptic MLAs.

In the example ofFIG. 10, plenoptic MLA102is deposited on spacing layer401having a different index of refraction than that of plenoptic MLA102itself. One skilled in the art will recognize that other arrangements are possible, including those in which spacing layer401has the same index of refraction as one or both of the layers1001of plenoptic MLAs102. Pixel-level MLA202and photosensor array107are omitted fromFIG. 10for clarity only.

As will be understood by those familiar with the art, the invention may be embodied in other specific forms without departing from the spirit or essential characteristics thereof. For example, the particular architectures depicted above are merely exemplary of one implementation of the present invention.

The functional elements, components, and method steps described above are provided as illustrative examples of one technique for implementing the invention; one skilled in the art will recognize that many other implementations are possible without departing from the present invention as recited in the claims. The particular materials and properties of materials described herein are merely exemplary; the invention can be implemented with other materials having similar or different properties.

The particular capitalization or naming of the modules, protocols, features, attributes, or any other aspect is not mandatory or significant, and the mechanisms that implement the invention or its features may have different names or formats. In addition, the present invention may be implemented as a method, process, user interface, computer program product, system, apparatus, or any combination thereof. Accordingly, the disclosure of the present invention is intended to be illustrative, but not limiting, of the scope of the invention, which is set forth in the following claims.

While the invention has been described with respect to a limited number of embodiments, those skilled in the art, having benefit of the above description, will appreciate that other embodiments may be devised which do not depart from the scope of the present invention as described herein. In addition, it should be noted that the language used in the specification has been principally selected for readability and instructional purposes, and may not have been selected to delineate or circumscribe the inventive subject matter. Accordingly, the disclosure of the present invention is intended to be illustrative, but not limiting, of the scope of the invention, which is set forth in the claims.