Holographic and diffractive optical encoding systems

Abstract

Holographic and diffractive optical encoding techniques for forming reflection or transmission holograms. The encoding device includes a substrate with an interference pattern that allows light to propagate from one side of the substrate to the other side of the substrate along a light propagation path. Furthermore, optical elements can be used to propagate the light according to a four-dimensional bright-field coordinate system. [Selected Figure] Figure 1

Description

[Technical field]

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS This application claims the benefit of priority to U.S. Provisional Patent Application No. 62 / 617,284, filed January 14, 2018, entitled “Holographic and Diffractive Optical Encoding Systems,” which is hereby incorporated by reference in its entirety.

[0002] FIELD OF THE DISCLOSURE This disclosure relates generally to optical technology, and more specifically to holographic and diffractive optical encoding systems for forming reflection or transmission holograms. [Background technology]

[0003] Holography is a technique that allows a light field to be recorded and then reconstructed when the original light field no longer exists because the original object is no longer present. Holography can be thought of as somewhat analogous to sound recording, whereby the sound field created by a vibrating object such as a musical instrument or vocal cords is encoded in such a way that it can later be replicated even if the original vibrating object is no longer present.

[0004] There are two basic types of holograms: reflection holograms and transmission holograms. Reflection holograms reflect light. A bright field is formed when the light used for reconstruction reflects off an interference pattern in the photographic medium. Transmission holograms transmit light. During reconstruction, light diffracts through the hologram. Reflection holograms generally provide the highest quality images, but are the most expensive to produce. Transmission holograms are the most commonly found, as they can be mass-produced cheaply in the form of embossed holograms. Credit cards often contain embossed holograms. It should be understood that the embodiments discussed herein can implement either type of hologram, and further that techniques for encoding either type of hologram and converting reflection holograms to transmission holograms and vice versa are well known in the art and need not be repeated herein. Summary of the Invention

[0005] An embodiment of a waveguide of the present disclosure may include a substrate comprising a photographic medium and an interference pattern encoded within the photographic medium, the interference pattern defining an array of substrate sites within the substrate. The interference pattern is configured to propagate light along optical propagation paths extending from an optical position on a first side of the substrate toward a second side of the substrate. The optical propagation paths comprise a plurality of sets of optical propagation paths extending through the same substrate site and the same optical position, each set of optical propagation paths extending in a substantially unique direction on the second side of the substrate and configured to converge from the same substrate site to the same optical position on the first side of the substrate, the unique direction being determined by the angular orientation of the chief ray propagation path within each set of optical propagation paths. Thus, the array of substrate sites is configured to propagate light according to a four-dimensional bright-field coordinate system with spatial coordinates defined for each substrate site by the position of the substrate site and angular coordinates defined by the unique orientations of the plurality of sets of optical propagation paths.

[0006] In one embodiment, the bright field is encoded as an interference pattern in a photographic medium. When properly lit, the interference pattern diffracts light into the original bright field and a replica of the objects that still appear to be there, exhibiting visual depth cues such as parallax and perspective that change realistically with any change in the observer's relative position. Photographic media, including photographic emulsions, can include dichromated gelatin, photoresists, photothermoplastics, photopolymers, and optical refractive index, among others.

[0007] In another embodiment, the array of waveguides may include a substrate comprising a photographic medium, an interference pattern encoded within the photographic medium, the interference pattern defining an array of substrate sites within the substrate, each substrate site comprising a plurality of substrate subsites, and an optical element, the optical element defining an array of optical element sites, each corresponding to a respective substrate site, each optical element site comprising a plurality of optical element subsite locations. The interference pattern is configured to propagate light to optical element subsite locations at each optical element site along optical propagation paths extending through the substrate subsites at each substrate site, the optical propagation paths comprising a plurality of sets of optical propagation paths extending through the same optical element site and the same substrate subsite at the corresponding substrate site. Each set of optical propagation paths extends from the optical element away from the substrate in a substantially unique direction and converges from different optical element subsite locations at the same optical element site to the same substrate subsite at the corresponding substrate site, the unique direction being determined by the angular orientation of the chief ray propagation paths within each set of optical propagation paths. The array of optical element sites is therefore configured to propagate light according to a four-dimensional bright field coordinate system with spatial coordinates defined by the positions of the optical element sites and angular coordinates defined by the unique directions of the sets of light propagation paths for each optical site. [Brief description of the drawings]

[0008] [Figure 1] FIG. 1 is an illustration of a holographic lenslet array ("HLA") site. [Diagram 2]FIG. 1 is an illustration of corresponding HLA and illumination source array ("ISA") sites. [Diagram 3] FIG. 1 is an illustration of the coordinate system for HLA and ISA sites. [Figure 4] FIG. 1 is an illustration of an alternative coordinate system for HLA and ISA sites. [Diagram 5] FIG. 1 is an illustration of the shapes of HLA and ISA sites. [Figure 6] FIG. 1 is an illustration of the coordinate systems of HLA and ISA subsites. [Figure 7] FIG. 1 is an explanatory diagram of the chief ray angle at the ISA subsite position. [Figure 8] FIG. 1 is an explanatory diagram of the principal ray propagation path at the HLA subsite location. [Figure 9] FIG. 13 is an illustration of a common input reference beam angle for an ISA subsite location and multiple HLA subsite locations. [Figure 10] FIG. 13 is an illustration of object beam angles for an ISA subsite location and multiple HLA subsite locations. [Figure 11A] 11A and 11B are illustrations of reference and object beam angles. [Figure 11B] Same as above. [Figure 12] FIG. 2 is a perspective illustration of three-dimensional reference and object beam angles. [Figure 13] FIG. 1 is an illustration of exemplary coding parameters of an interference pattern of the present disclosure. [Figure 14] FIG. 1 is an illustration of a first embodiment of encoding an interference pattern of the present disclosure. [Figure 15] FIG. 13 is an illustration of a second embodiment of encoding an interference pattern of the present disclosure. [Figure 16] FIG. 13 is an illustration of a third embodiment of encoding an interference pattern of the present disclosure. [Figure 17] FIG. 1 is an explanatory diagram of prerequisites for direct HLA encoding. [Figure 18] FIG. 1 is an illustration of the convergence of light rays at the ISA subsite position. [Figure 19] FIG. 1 is an illustration of exact convergence in a hypothetical HLA element. [Figure 20] FIG. 1 is an illustration of an uncorrected virtual HLA reproduction. [Figure 21] FIG. 1 is an illustration of a desired virtual HLA reproduction. [Figure 22] FIG. 1 is an illustration of diffractive optical element ("DOE") correction. [Figure 23] FIG. 13 is an explanatory diagram of DOE-corrected virtual HLA reconstruction. [Figure 24] FIG. 1 is an explanatory diagram of coding in a virtual HLA plane. [Diagram 25] FIG. 1 is an explanatory diagram of ISA reference beam encoding. [Figure 26] FIG. 13 is an illustration of ISA illumination source reconstruction. [Figure 27] FIG. 1 is an illustration of one embodiment of a DOE site. [Figure 28] FIG. 1 is an illustration of coding considerations for a large ISA site. [Figure 29] FIG. 1 is an illustration of a multiple element DOE HLA optical system. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] An embodiment according to the principles of one aspect of the present disclosure may include a holographic lenslet array (herein "HLA") that may include interference patterns encoded in a photographic medium that define two unique planes, i.e., many unique holographic elements, and an illumination source array (herein "ISA") that may be positioned below the HLA. The HLA elements may be divided into N x M subsites, each at the HLA subsite location. An aspect of the present disclosure describes the encoding of these subsites such that the HLA elements essentially function as an array of lenses. An embodiment according to the principles of another aspect of the present disclosure may include encoding an interference pattern configured to direct light similar to an ISA onto an optical element having optical element subsites similar to the HLA subsites.

[0010] 1, which illustrates one embodiment of an HLA 100, the HLA 100 may include multiple HLA elements 102, each with an individual digital hologram encoded to substantially replicate the properties of a theoretically perfect lens. These holograms may have digitally constructed light profiles and functions associated with, but not limited to, micro-optical elements.

[0011] Referring to FIG. 2, which illustrates one embodiment of the ISA 200 , the ISA includes multiple light sources that direct light to corresponding locations on the HLA sites 102 .

[0012] In one embodiment, the HLA and ISA planes are each subdivided into a number of locations called sites. In one embodiment, each site may be independently encoded. The HLA and ISA sites may be in a regular, irregular, or overlapping configuration. Figure 1 shows a diagram of an HLA site 102.

[0013] In one embodiment, the HLA and ISA sites may be regularly packed rectangles with overlapping regions between the ISA sites, as shown in Figure 2. It is understood that other designs following the principles disclosed herein may be used and are contemplated by this disclosure.

[0014] The desired number of HLA and ISA sites per display defines the viewable resolution of the display and the size of each physical site, which is defined by the following formula:

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[0015] In the formula, H WH and I WH are the physical width and height measurements of each HLA and ISA site, respectively, and D WH are the total width and height of the entire display surface, and DN XY is the total number of individual HLA sites in the vertical and horizontal dimensions for the entire HLA display surface, and O XYis the overlap coefficient, which accounts for the fact that each ISA region can be larger than its corresponding HLA region. These parameters are shown in Figures 1 and 2. XY If is non-zero, then an illumination source lying within the overlap region of an ISA may contribute not only to the HLA immediately above it, but also to at least one adjacent HLA.

[0016] The irregular configuration can be determined by more advanced calculations.

[0017] The locations containing the concentric HLA and ISA site pairs are arranged in a regular coordinate system that can be indexed by the variable i in the x direction and the variable j in the y direction: HLA H ij <=>ISA I ij

[0018] The origin i,j=0,0 is placed at the center of the display as shown in Figure 3. The range of values ​​for i and j is:

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[0019] For simplicity, HLA H ij and ISA I ij The pairs of are collectively called HI ij It is called. H ij and I ij Pair <=>H ij

[0020] HI ij Each of the positions has a dimension D W ×D H 1 represents a single optical element 300 with corresponding HLA and ISA sites from within an overall display system having

[0021] D W ×D H may indicate the variation of W, H values ​​across the surface of the display system and may be expressed as a function of index position.

[0022] HI 00 Even, odd, and non-integer DNs that are not centered at an HLA site XY In order to properly compensate the value, as shown in Figure 4

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[0023] Indices HI of the two coordinate systems ij and

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[0024] By properly describing the optical center of each HLA, each HI with respect to the origin of the display ij The exact location of the element's center can be calculated. HI ij x c = i × HLA W HI ij y c =j×HLA H

[0025] By describing the coordinates of the holographic lens array, each HI in the system ijThe site 300 may now include an additional subsite coordinate system defined by N subdivisions on the x-axis and M subdivisions on the y-axis. ij Both the ISA and HLA sites of site 300 are each subdivided into N×M individual regions. To fully specify a set of coordinates for an HI element, the following notation is used: HI ij n H m H n I m I

[0026] where ij is the index of the ISA and HLA site of the HLA element, and n H m H represents the index of the HLA subsite of the HLA site, while n I m I represents the index of the ISA subsite of the ISA site.

[0027] As shown in Figure 5, the size of each HLA subsite is ij It is determined by dividing the width of the HLA site 502 of the HLA optical element 500 by N on the x-axis and dividing the height of the HLA site 502 by M on the y-axis. Similarly, the size of the ISA subsite is determined by dividing the width of the HLA site 502 of the HLA optical element 500 by N on the x-axis and dividing the height of the HLA site 502 by M on the y-axis. ij The HLA is defined based on the width and height of the ISA site 504 of the optical element 500 .

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[0028] Each HLA and ISA subsite can exhibit different values ​​for each site, which can be expressed as a function of index position.

[0029] Although the HLA and ISA may have different dimensions, each HI ij The HLA optical elements may share a common (0,0) point at the center. H m H n I m IThe subsite index can be treated in the same manner as the ij HLA element index above, as follows:

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[0030] Each HI ij Both HLA and ISA subsites in share the same N×M coordinate system, but may have different physical locations between the planes outside the central axis, where n I =m I =n H =m H =0.

[0031] The physical location of a particular HLA subsite in units of length is given by the formula:

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[0032] Similarly, the physical location of a particular ISA subsite in units of length is given by:

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[0033] Each index may be defined by an integer or an integer minus 0.5. H ,m H It has also been found useful to define an alternative coordinate system when (0,0) is not centered on the HLA subsite. As shown in FIG. 6, this coordinate system when (0,0) is in the lower left corner of the subsite is:

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[0034] It should be noted that while all of the above assumes that the configuration of HLA and ISA sites is uniform and regular, such a configuration should not be understood to be required, and it should be understood that the principles of the present disclosure may be applied to other configurations of HLA and ISA sites contemplated herein.

[0035] The distance 706 between the parallel HLA plane 702 and the ISA plane 704 is denoted by f. This parameter is ij The ISA subsite position n is designed to provide control of the field of view ("FOV") and chief ray angle ("CRA") of any ISA subsite position n, as shown in FIG. I ,m I , the index (n H ,m H )=(0,0), the HLA element H ij It is a ray that connects to the center of the HLA site.

[0036] The maximum total FOV angle of each HLA is determined by the following formula:

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[0037] The CRA half angle formed between the center of the HLA site and the ISA subsite position is the ISA subsite position coordinate

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[0038] As shown in Figure 8, n I , m IFor each ISA subsite position defined by ij Each ISA subsite position (n I ,m I Note that there are different CRAs that represent a set of CRA angles, one for each (n H ,m H )=(0,0), the input reference beam angle is equal to the output object beam angle (assuming a system with equal steps between each of the formed CRA angles, uniformly sized HLA subsites, and uniformly sized ISA subsites).

[0039] It should be understood that both the CRA angles and the HLA / ISA sites may be defined by irregular intervals or angles in more complex optical configurations, and the principles of this disclosure may be applied to these configurations as contemplated herein.

[0040] In one embodiment, each individual HLA site Hij is encoded as follows: A) Each ISA subsite position as shown in Figure 9

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[0041] To illustrate the principles of the present disclosure, an embodiment is provided in FIG. 13 as Example A. In Example A, illumination source prerequisites for consideration may include: Bayer RGB, non-laser, diffuse lighting source plane ●Diffusion surface at the HOE focus ● White light must be visible -Transmission elements between the viewer and the illumination source

[0042] In embodiment A, single HOE encoding outperforms the state-of-the-art (SOTA) HOE encoding methodology. Limitations of the SOTA process include: ●100um 2 Minimum subsite encoding size ● Maximum of 1 reference angle (θφ) per 10 degrees with a multiplied effective transmission reduction of 1 / (θ×φ) (check prerequisites) Effective transmission of 1 / L (or less), where L = number of multiplexed λs

[0043] Given the above discussion of the structural relationships of HLA and ISA sites and subsites, and the encoding of HLA sites to multiple ISA subsite locations within an ISA site, one skilled in the art will understand that the principles of one embodiment of the present disclosure may be implemented in a waveguide.

[0044] In one embodiment, a waveguide of the present disclosure may include a substrate comprising a photographic medium and an interference pattern encoded within the photographic medium such that the interference pattern defines an array of substrate sites within the substrate. In one embodiment, the interference pattern comprises a hologram encoded to direct light as an array of lenslets, thereby forming a holographic lenslet array ("HLA") as discussed above. The HLA may include a plane subdivided into sites, such as sites Hij as discussed above. The HLA sites correspond to substrate sites. Additionally, the interference pattern of the substrate may be configured to propagate light along a light propagation path that extends from a light location (e.g., an ISA subsite location) on a first side of the substrate (e.g., HLA site Hij) toward a second side of the substrate (e.g., HLA site Hij). Examples of light propagation paths are shown in Figures 10-12 above.

[0045] In one embodiment, the light propagation paths include multiple sets of light propagation paths that extend through the same substrate site (e.g., HLA site 1108 in FIGS. 11A and 11B, or HLA site 1204 in FIG. 12) and the same optical position (e.g., ISA subsite positions 1102 and 1104 in FIGS. 11A and 11B, or ISA subsite position 1206 in FIG. 12), with each set of light propagation paths extending in a substantially unique direction on the second side of the substrate as shown in FIG. 10 and configured to converge from the same substrate site to the same optical position on the first side of the substrate. As shown in FIG. 10, the unique direction is determined by the angular orientation of the chief ray propagation paths within each set of light propagation paths.

[0046] In one embodiment, as discussed above with respect to Figures 7-9, the chief ray propagation paths comprise light propagation paths between one of the ISA subsite locations and the center of a corresponding respective subsite of the HLA. The unique direction of each set of light propagation paths is determined by the chief ray angle ("CRA") of the respective chief ray propagation path. Thus, the array of substrate sites is configured to propagate light according to a four-dimensional bright-field coordinate system with spatial coordinates defined by the location of the substrate sites (e.g., HLA site 1108 in Figures 11A and 11B, or HLA site 1204 in Figure 12) and angular coordinates defined by the unique directions (e.g., CRA) of the sets of light propagation paths of each substrate site location.

[0047] In one embodiment shown in Figures 10-12, for each ISA subsite position of the first site of the ISA, a corresponding site of the HLA in the interference pattern is encoded by a common input reference beam angle determined by the CRA of the respective chief ray propagation path for each ISA subsite position, and by an output object beam angle determined by the light propagation paths converging from the HLA subsite positions in the corresponding site of the HLA to each ISA subsite position of the first site of the ISA.

[0048] In one embodiment, the encoding methodology for encoding the HLA sites assumes that for each N×M input reference angle, there are associated N×M output object angles, as defined in the discussion above, and a single beam is generally separated into reference and object beams when performed by the holographic encoding methodology. As shown in FIG. 14, for a first site 1402 of the ISA and a corresponding site 1404 of the HLA, one of the respective HLA subsite locations 1406 is encoded at a time by a common input reference beam angle 1410 of a single respective ISA subsite location 1408, and one pair of output object beam angles 1412 of a single respective ISA subsite location 1408.

[0049] While it should be understood that illustrations of the present disclosure, such as Figure 14, show an object beam from below or from the opposite side of the reference beam and thus may represent a reflection type hologram, etc., those skilled in the art will readily appreciate that the illustrations provided herein are intended only to illustrate the principles of the present disclosure and are not limiting. Based on the principles disclosed or illustrated in this disclosure, it should be readily apparent to one skilled in the art that the embodiments of the present disclosure need not have the precise orientation shown, and that the encoding methodology of the present disclosure may be implemented using the same / similar side, edge, off-axis embodiments providing for transmission, volume, edge illumination, gratings, diffraction, refraction, etc.

[0050] Those skilled in the art will appreciate that encoding the photopolymers described in this disclosure involves additional optics, motor control systems, and photonics.

[0051] The encoding approach of FIG. 14 may include associated hardware known in the art for reflective, transmissive, and / or volume holographic photopolymer media, etc., and provides the most flexible, but most time-consuming, optical digital encoding configuration, such that there is a one-to-one mapping between the input and output beams.

[0052] In this system, the reference and object beams are Wijnm , H Hijnm and having a spot size of

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[0053] However, an exemplary 1.731 x 1.731 mm 2 For an HLA element size of , the SOTA limits above are 33% transmission per color and approximately 289 (17 2 ) allows for a single reference beam per wavelength at the coding HLA subsites.

[0054] In comparison, embodiment A provides a subsite encoding size of 27×40.5 um and 2,741.3 (64.125×42.75) encoded HLA subsites.

[0055] Additionally, each HLA subsite can be configured to provide a unique output angle for each of the N×M reference angles. However, the SOTA provides a maximum of 36 (6×100) at the expense of 1 / 36 effective transmission multiplied for a 1 / 3 multiplexed RGB transmission reduction. 2 ) reference angle, resulting in only about 1% of the transmitted illumination per subsite being visible for a fraction of the required encoded information.

[0056] Alternatively, for a more efficient encoding methodology, multiple HLA or ISA subsite locations may be encoded simultaneously by fabricating offset optics that produce the desired effect for encoding the HLA. This can be done in one of two different ways, due to the functionality of the encoding system.

[0057] In one embodiment, as shown in FIG. 15 , a plurality of HLA subsite locations 1504 of an HLA site 1502 are aligned with each possible ISA subsite location 1506 having a common input reference beam angle 1512 and a respective plurality of output object beam angles 1510.

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[0058] In one embodiment, as shown in FIG. 16, one of the HLA subsite locations 1602 at an HLA site 1604 is encoded at one time with a plurality of common input reference beam angles 1610 for a plurality of ISA subsite locations 1606 at an ISA site 1608, and a plurality of output object beam angles 1612 for each of the plurality of ISA subsite locations 1606. This process is repeated for other HLA subsite locations 1602 with corresponding converging object beam rays. This approach may be implemented with offset optics designed to converge at a single subsite location, and the angle formed is the reference angle for the designated HLA subsite location, ISA n H , m H Accurately reconstruct the required angle formed between the subsite location and the required reference angle that defines the desired HLA subsite FOV. The optical elements here are shown folded for illustrative purposes only. The reference beam angle may be further defined or limited by a photopolymer reaction.

[0059] While it should be understood that the illustrative diagrams of the present disclosure, such as Figures 15 and 16, show the object beam from below or from the opposite side of the reference beam and thus may represent reflection holograms and the like, one of ordinary skill in the art will readily appreciate that the illustrative diagrams provided herein are intended only to illustrate the principles of the present disclosure and are not intended to be limiting. Based on the principles disclosed or shown in this disclosure, it should be readily apparent to one of ordinary skill in the art that the embodiments of the present disclosure need not have the precise orientation shown, and that the encoding methodology of the present disclosure may be implemented using the same / similar side, edge, off-axis embodiments providing for transmission, volume, edge illumination, gratings, diffraction, refraction, and the like.

[0060] Utilizing real optics rather than the brute force methodology described in Figure 14 limits the accuracy of the encoding procedure not only to the accuracy of the motion control hardware, but also to the accuracy of the optics itself. However, this brute force methodology does not limit the maximum N 2 ×M 216 involve only N×M encoded exposures, due to the fact that the input and output angles are paired together during each exposure. In FIG. 15, all HLA subsites are encoded simultaneously for each CRA, and in FIG. 16, all angles are encoded simultaneously for each HLA subsite.

[0061] Each of these embodiments provides conversion to the appropriate transmission and / or volume hologram to produce the expected optical effect.

[0062] The above encoding methodologies may be limited by the maximum density of encoding sites within the photopolymer.

[0063] Virtual HLA encoding: In addition, it is possible to decouple the ISA and HLA planes by encoding for the virtual plane, which may consider either the HLA plane or the ISA plane, and the following disclosure focuses on the encoding procedure for the virtual HLA plane and the physical ISA for illustrative purposes only.

[0064] In the above discussion, the HLA site is simultaneously coded for both the input and output angles, and therefore N 2 ×M 2 It is envisaged that this would create a requirement to encode individual HLA subsite positions.

[0065] However, this means that each H ij n H m H n I m I For the HLA subsite positions, the HI ij n H m H n I m I It is assumed that the input reference beam converges and the output object beam diffracts as a function of coordinate pairs.

[0066] This means that when repeated for all subsite locations, for each optical element, the required H ij n H m H n I m I Form all of the input reference and output object angles. However, this requires N 2 ×M 2 This sacrifices the need for multiple encoding angles and complicates the replication process by requiring multiple reference beam angles. Direct encoding is the simplest method since this plane is the desired convergence point for the optical element and forms an almost direct substitute for any such other form of optical component.

[0067] However, for a given Hijn I m I When tracing the convergent rays from the ISA plane to the HLA plane from the coordinates, the required input reference angle as defined by the CRA can be viewed as the same parallel rays rather than the fluctuating convergent and diffracted rays as shown in Figure 18, which is the same n,m coordinates as shown in Figure 17, but now convergent in the ISA plane, and all of the input reference rays as refined are now viewed as parallel rays in the virtual HLA plane rather than convergent and diffracted.

[0068] Thus, the encoding process can be simplified to allow a single reference beam angle to be encoded for the necessary angles, as needed, to properly converge at the virtual HLA plane.

[0069] Exemplary Encoding Methodology When encoding for the desired focus position in the ISA plane, it is possible to focus the rays to the required HLA subsite position with only a single reference beam orientation and offset the optics to form a virtual HLA plane.

[0070] In addition, each ISA site will have a coordinate position H Wijnm , H Hijnmis greater than I Wijnm , I Hijnm It should be noted that the physical dimensions of the subsites may be shown. For the exemplary values ​​provided in Figure 13, each ISA subsite is 27 x 40.5 um for an HLA subsite size of approximately 54 x 81 um. With a virtual HLA encoding methodology in the ISA plane, the SOTA encoding technique is approximately capable of producing the desired encoding density.

[0071] By this methodology, it is possible to accurately form all of the rays converged at the HLA plane as shown in FIG. 19, but upon reconstruction, the rays are no longer accurately converged at the HLA plane, as they are unconstrained and no longer diffract as shown in FIG.

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[0072] For certain applications, the above uncorrected results highlighted in FIG. 20 may be sufficient and can be compensated for by the original image source to compensate for any visual distortions that may occur.

[0073] However, for most applications, HI ij n H m H n I m I It is desirable to closely maintain the correct angle when formed by the lens to ensure that adequate viewing image quality is maintained.

[0074] Additional N 2 ×M 2To achieve this without relying on the individual encoded HLA correction angles, it is possible to add optical elements such as lenses or relatively simple diffractive optical elements ("DOEs") that exhibit multiple angular dispersions across the optical surface to more precisely diffract the light rays to the desired angles beyond the HLA plane. The fabrication of these DOEs can be produced through a number of different DOE fabrication methodologies known in the art. It is understood that the embodiments herein may be discussed with reference to DOEs, but that the present disclosure contemplates embodiments in which the DOEs may be replaced with other optical elements, such as lenses, to enable the same optical effect.

[0075] In the simplest approach, a DOE is characterized by a diffraction value determined for each of the hypothetical N×M HLA subsite positions. ij n H m H Subsite location is ISA I ij All N × M output object angles from are simultaneously corrected.

[0076] Each H ij n H m H A single subsite location configuration

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[0077] Given Desired

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[0078] Throughout this discussion, we often use the normalized system based on + / -(nHIm HI ) It is easier to discuss the location,

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[0079] Generally speaking, given

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[0080] In view of the particular complexities of this DOE design, to help state these corrections more clearly, we consider all H from 0 → (N-1), 0 → (M-1) ij n' H m' H A single I ij n I m I In position

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[0081] FIG. 22 is an exemplary table that helps illustrate the uncorrected virtual HLA angles that form when generating a HOE (e.g., a photographic medium encoded with an interference pattern) for the ISA plane, the angles defined as a perfect lens, the DOE correction factors applied to each subsite location, and the resulting angles that form when the DOE corrections are applied. It will be apparent that these angles, although perhaps not perfect, will be close to the ideal goal even when only a single correction prescription is applied. All the above values ​​should be considered merely exemplary, as any particular application will require different considerations. The values ​​explicitly stated in FIG.

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[0082] FIG. 23 is a diagram showing a corrected virtual HLA reconstruction with DOE correction elements in the virtual HLA plane. The virtual HLA is reconstructed by only a single DOE correction optical value for each n, m virtual HLA subsite position. ij n H m H n I m I It is possible to approximately correct the angle to the exact angle defined by

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[0083] In one embodiment, the correction shown in Figure 23 may be implemented by an interference pattern that is coded to direct light similar to the ISA discussed with reference to Figures 8-12, and an optical element configured to direct light similar to the HLA discussed with reference to Figures 8-12. In one embodiment, the interference pattern may define an array of substrate sites in a substrate similar to the ISA sites discussed with reference to Figures 1-12, each substrate site comprising a plurality of substrate subsites (similar to the ISA subsites). The optical elements may define an array of optical element sites similar to the HLA sites discussed with reference to Figures 1-12, each corresponding to a respective substrate site, each optical element site comprising a plurality of optical element subsite positions (similar to the HLA subsite positions). The optical elements and interference patterns are configured such that each set of light propagation paths extending through the same optical element site and the same substrate subsite of the corresponding substrate site extend from the optical elements in a substantially unique direction away from the substrate and converge from different optical element subsite positions of the same optical element site to the same substrate subsite of the corresponding substrate site, the unique direction being determined by the angular orientation of the chief ray propagation paths within each set of light propagation paths.

[0084] FIG. 24 is an explanatory diagram of one embodiment of an encoding method for an ISA site 2402. IThe subsite positions of are encoded by a reference beam from the bottom and an object beam angled collimated ray based on the desired CRA angle defined by the ISA subsite positions. The reference optic may or may not indicate an angle and may or may not include an offset encoded ray.

[0085] As discussed above, it should be understood that the illustrative diagrams of the present disclosure, such as Figures 23 and 24, show the object beam from below or from the opposite side of the reference beam and therefore may represent reflection holograms and the like, however, one of ordinary skill in the art will readily appreciate that the illustrative diagrams provided herein are intended only to illustrate the principles of the present disclosure and are not intended to be limiting. Based on the principles disclosed or shown in this disclosure, it should be readily apparent to one of ordinary skill in the art that the embodiments of the present disclosure need not have the precise orientation shown, and that the encoding methodology of the present disclosure may be implemented using the same / similar side, edge, off-axis embodiments providing for transmission, volume, edge illumination, gratings, diffraction, refraction, and the like.

[0086] With this encoding methodology, the mechanical and optical process is much simplified and the object beam (now above the HLA plane) is precisely focused at the desired ISA plane based on the CRA and by the parallel rays that can fill the entrance pupil of the optical elements, converging the rays to produce the required angle as defined. The optical elements do not necessarily have to move, but rather the collimated beam can be precisely oriented to compensate for the required angle of the CRA. The optical elements of the reference beam (now below the ISA plane) are much simplified and do not necessarily have to be angled in any particular way, as their position now represents the illumination plane, which is a diffuse illumination surface. These beams can be offset, orthogonal, and / or angled depending on the characteristics of the encoding system.

[0087] To compensate the illumination surface for reconstruction, it is possible to generate a set of divergent beams that mimic the behavior of a specified light source. In one embodiment, the coded reference optic (or object beam of any of the above disclosures) is aligned with the holographic optical element subsite H, with the beam passing through the focal point of a converging optical assembly as depicted in FIG. Wijnm , I Hijnm A range of angles may be intentionally created when creating a range of illumination angles limited to 1000 nm. As discussed elsewhere in this disclosure, the holographic optical element may include a substrate with a photographic medium encoded with an interference pattern, in the embodiment of Figure 25, the encoded interference pattern includes a substrate site 2502 having subsites 2504.

[0088] As shown in FIG. 26, for a given illumination source 2602 indication, the encoded angles now accurately reconstruct the encoded object beam without the need for a laser illumination source.

[0089] Depending on the profile of the illumination pixel, other optical configurations are included that may include multiple smaller elements, different focal lengths, apertures, offsets, and / or various other optical reconfigurations to precisely reduce the requirement for a collimated beam for proper use of the HOE elements.

[0090] Additionally, other DOE elements may be utilized in the illumination source to more accurately generate a nearly collimated beam from a non-coherent / non-collimated illumination source, for example, a micro-Fresnel or kinoform element.

[0091] Each DOE subsite position can be divided into dx, dy subdivisions. x , d y It is possible to divide it into subdivisions, n H m H It serves to modify the above DOE correction calculations by additional functions based on the coordinates and / or to add additional DOE optical elements before or after the virtual HLA plane.

[0092] Assuming a virtual HLA spot size smaller than the HLA subsite itself, we have a single DOE element offset below or above the virtual HLA plane, x , d y It is additionally possible to utilize a subdivision correction mechanism methodology. This offset allows for the diffraction of rays that are not yet converged (below) or just beyond the convergence point (above) in the desired HLA plane, and at this point H ij n H m H distributed over a larger spatial distribution within the subsite locations and encoded only by a single or multi-element DOE plane(s). x , d y It is possible to create beams that provide additional control with finer subdivision.

[0093] The simplest approach is to place the HOE above a virtual HLA plane to compensate for potential diffraction errors, and the resulting subdivision is HI ij n H m H d x d y It can be expressed as: Each d x , d y The coordinates represent the local coordinate system of each nH, mH subsite, resulting in an offset position close to where the converging rays from the virtual HLA plane just begin to intersect the adjacent subsite rays, as shown in Figure 27. H Distance H indicating the second element DOE subdivisions Ox, Oy juxtaposed at the distance where the light rays converge between adjacent subsite locations D 27 shows an exemplary multi-element DOE correction element having a first element 2702 and a second element 2704 arranged at a position 2706 of the second element DOE. Also shown is an alternative position 2706 of the second element DOE.

[0094] The same logic can be applied to the multi-element designs presented above, utilizing similar considerations implemented by a single DOE correction provision.x , d y Through the addition of subsite locations, additional corrections can be refined.

[0095] Other correction opportunities include the addition of a virtual H ij n H m H One approach is to holographically encode the subsite positions into finely divided exit angles. In this manner, it is possible to vary the application of corrections based on the entrance angle (defined from the ISA plane to the DOE element), with different corrections applied based on the entrance angle. This can be done as a single element, in conjunction with the DOE element, or as a varying multi-element optical design.

[0096] ISA>HLA Region Considerations In addition, it should be noted that the complexity of encoding the ISA HOE is more complex when encoding for an ISA region that is larger than the HLA region. In this case, some illumination plane subsites contribute simultaneously to more than one HLA. For example, if the ISA overlap coefficient is non-zero in only one axis (e.g., OX=1 and OY=0), then each ISA source contributes to two different HLA elements. More specifically for this example, for any one HLA site H ij Regarding the concurrent ISA I ij Encoding must occur: 1) all subsites are ij 2) negative n I The subsite contributes to the neighborhood in the negative x direction, and 3) positive n I The subsites contribute to their neighbors in the positive X direction. The encoding process for this example arrangement requires three different coherent light and lens sources. The diagram in Figure 28 shows the O X Three planar HLA lenses are shown, taking into account an overscan of 1.

[0097] To compensate for the number of HLA lenses contributing to the final ISA subsite coding area, there are a number of ways to accommodate this factor, the simplest being lens multiplexing as depicted in Figures 14-16. This additionally requires splitting multiple beams into different optical regions to accommodate the required CRA of each lens throughout the coding process for each of the n,m subsites.

[0098] Similarly, if overlap exists in both dimensions (O X =1 and O Y =1), up to nine separate lenses may be required simultaneously when encoding these overscan regions.

[0099] Optical design with only diffractive elements While there are certain advantages to encoding the HOE, it is possible to engineer a given optical system design with single or multi-element arrays of diffractive optical components.

[0100] Diffractive optical elements (DOEs) allow the advantage of leveraging well-established and refined fabrication methodologies. These elements, such as multi-level phase zone plates (PZPs), can be fabricated in thin sheets with thicknesses of less than 1 mm, and multiple planes of such elements can be used to create lensing functions. The illustration in Figure 29 shows a ray trace of one such design, which includes three diffractive optical elements with unique diffraction properties for each element and for each subsite position.

[0101] DOE systems can additionally be fabricated taking into account a virtual HLA or using diffractive optics in the ISA plane.

[0102] DOE elements generally suffer from a degradation in overall imaging quality given the large negative chromatic aberration they introduce. This can be addressed by using a hybrid between refractive and diffractive elements to achieve the lens function instead. A simple refractive lens can be attached to a thin DOE element in such a way that the large negative chromatic aberration of the DOE is compensated by the positive chromatic aberration of the lens. Such a hybrid combination can reduce distortion and produce a more uniform point spread function (PSV) across the image plane, improving the off-axis performance of a single simple lens.

[0103] Additional considerations: Other options were considered to reduce the necessary HOE resolution requirements, including: • Multiplexing each subsite to form a pattern of different encoding wavelengths similar to a Bayer pattern; Layering multiple HOEs together to form more complex optical systems from a larger overall holo pixel; and Simply temporarily abandon the concept of replicating the lens aperture characteristics and provide each illumination pixel with an independent input reference and output object angle, at the expense of significantly reducing the viewable illumination.

[0104] To account for photopolymer limitations and limit transmission losses, ideally each subsite would be further divided into an additional series of N x M subsites, each representing a single, series, and / or multiplexed RGB characteristic (or some value larger or smaller, depending on which variables are multiplexed or removed).

[0105] In its simplest form, sub-dividing every subsite into N x M "sub-subsites", each having only a single input reference and output object angle respectively coded (at the expense of lower visible transmission so that each subsite now only shows 1 / (N x M) of the total illumination previously assumed), and each having only a single color coded (with a repeating pattern of RGB with a loss of 1 / 3 of the angle coding resolution per subsite, or with some other similar pattern, or alternatively multiplexing for RGB), each of the resulting sub-sub coding sites is now approximately (27.4um / 60 x 41.1um / 40) 456um x 1.0275um.

[0106] Alternatives: Considering that the input reference angle should ideally be a single beam (for N×M), and that a single reference beam can produce complex output angles, it is possible to directly encode the ISA plane versus the HLA plate to form a virtual HOE plane.

[0107] In some embodiments, additional considerations may be included where this methodology is more appropriate. 1. Rather than directly encoding the input reference, we directly encode the ISA coordinates by a process similar to that proposed above. 2. The illumination source is not natively collimated, but it is possible to create a near-collimated illumination source per ISA site by placing a HOE directly on the ISA surface as close to the illumination plane as possible with a simple diffractive element (e.g., kinoform or similar), and / or a pinhole mask array, and / or appropriate refractive matching adhesives and / or materials. This can also be explored for all of the above considerations. 3. At this point, the input reference beam is from a single angle (ideally perpendicular to the normal to the HOE surface or another direction compensated for by a diffractive optical element) and the object beam utilizes a series of optical elements to expand the beam and focus it to the same ISA coordinates as the reference beam. 4. The object beam is shaped to correspond to: a. Size of HLA optical element w×h at virtual f distance from ISA encoding site b. Angling the CRA appropriately so that it passes through a ray that intersects both the center of the virtual HLA and the ISA-encoded coordinates. c. have appropriate aperture and focal length, taken as a whole, so that the light rays converge at the ISA in proper agreement with the diagram provided above; d. When viewed as a reflection (or other) hologram

[0108] Note: The w×h of the ISA may need to match the HLA at this point, or the HLA is potentially (much) larger in the virtual coordinate system. This may not be a problem, and may allow for multiple encoding angles where the specified ISA overlap region may be offset by some amount, or even more than 10°.

[0109] Or alternatively, each ISA subsite is encoded with each partially covered from exposure by a masked portion of the object beam such that only a "pie-shaped" segment from the complete beam is focused at the HOE to provide a portion of the entire lens. In the current embodiment, there is a 200% overlap between each of the HLAs and ISAs, resulting in a maximum of four shared HLAs per ISA coordinate. This results in a quarter interference pattern exposure that maintains this relationship, which should be possible with this approach or some combination of segments and multiplexing.

[0110] At this point, since all of the light rays (when viewed as a transmission / volume or similar replicated hologram) pass through the HLA coordinate system, the challenge may be that the light rays are no longer collimated from the reference beam and associated diffracted object beam as originally envisioned by the encoding scheme; the light rays emanating from the illumination source continue to travel through space, passing through the virtual HLA plane, without any further angle changes, as necessary, to properly view each HLA subsite. Depending on the ideal viewing distance and subsite FOV, this may or may not be a major issue (currently assumed to be at the expense of viewable image quality).

[0111] However, the addition of a second (or more) HOE at or near the location of the virtual HLA plane has the ability to encode a corrective treatment of the rays passing through each of these virtual HLA subsite coordinates.

[0112] Each coordinate in the virtual HLA now has the convergent contributions of rays from all ISA subsites. At this point, the addition of diffractive elements (e.g., kinoforms, gratings, Fresnel arrays, etc.) can be designed to correct the CRA from each of the HLA subsites, and the central ray from the set of ISA ray bundles can be calculated and corrected to meet the desired HLA specifications.

[0113] In this manner, in addition, it is possible to create a simple digital holopixel by the same method as explicitly stated above to perform this correction, where the CRA from the object beam (at this point its location from the previous reference beam is reversed) is formed to diffract the erroneously diverging light rays into the correct orientation, matching the required correction factor, by changing the focal length, aperture, position and rotation according to the most ideal configuration of the given reference beam.

[0114] Other approaches contemplated in this disclosure: Encode the master HOE as an edge-lit hologram and include this illumination source as an element in the final display throughout the replication Converting a master from a reflection / volume / transmission to a transmission / reflection / volume hologram by offsetting the replica plane from the HLA position (or original placement position depending on the configuration implemented) to the ISA plane (or an alternative plane) to allow conversion between the master and various replicas Converting a master or replica from a reflection / volume / transmission hologram to a reflection or transmission edge-lit hologram by a laser illumination source optimized and controlled based on the encoding process to provide a higher quality HOE without the use of white light, providing the ability to view the encoded optical properties.

[0115] Although various embodiments according to the principles disclosed herein have been described above, it should be understood that these embodiments are presented for illustrative purposes only and are not limiting. Thus, the breadth and scope of the invention(s) should not be limited by any of the exemplary embodiments described above, but should be defined only in accordance with the claims that derive from this disclosure, and their equivalents. Moreover, the above advantages and features are provided in the described embodiments, but do not limit the application of such claims to processes and structures that achieve any or all of the above advantages.

[0116] It should be understood that the principal features of this disclosure can be employed in various embodiments without departing from the scope of the disclosure. Those skilled in the art will recognize, or be able to discover using no more than routine experimentation, many equivalents to the specific procedures described herein. Such equivalents are considered to be within the scope of this disclosure and are covered by the claims.

[0117] In addition, the section headings herein are provided for consistency with the teachings under 37 CFR 1.77 or to otherwise provide organizational guidance. These headings are not intended to limit or characterize the invention(s) described in any claim that may originate from this disclosure. Specifically, as an example, even if a heading is entitled "Field of the Invention," such claims should not be limited by the language of this heading to describe the so-called technical field. Furthermore, the description of a technology in the "Background of the Invention" section should not be construed as an admission that the technology is prior art to any invention(s) in this disclosure. The "Summary" is in no way intended to characterize the invention(s) described in the claims at issue. Furthermore, references to the singular "invention" in this disclosure should not be used to assert that there is only a single novelty in this disclosure. Multiple inventions may be described according to the limitations of multiple claims originating from this disclosure, and such claims thus define the invention(s) and their equivalents protected thereby. In all instances, the scope of such claims will be considered on their own merits in light of this disclosure, but should not be constrained by the headings set forth herein.

[0118] The words "a" or "an" when used in conjunction with the term "comprising" in the claims and / or specification may mean "one," but it is also consistent with the meanings of "one or more," "at least one," and "one or more than one." The term "or" used in the claims is used to mean "and / or" unless expressly referring to alternatives only or the alternatives are mutually exclusive, but the present disclosure supports the definition referring to alternatives only and "and / or." Throughout this application, the term "about" is used to indicate that a value includes the inherent error variation of the device and the method is used to determine the value, or the variation that exists among the research subjects. Generally, but subject to the foregoing considerations, numerical values ​​herein modified by approximation words such as "about" can vary from the stated value by at least + / - 1, 2, 3, 4, 5, 6, 7, 10, 12, or 15%.

[0119] As used in this specification and claim(s), the words "comprising" (and any form of comprising, such as "comprise" and "comprises"), "having" (and any form of having, such as "have" and "has"), "including" (and any form of including, such as "includes" and "include"), or "containing" (and any form of including, such as "contains" and "contain") are inclusive or open-ended, and do not exclude additional, unrecited elements or method steps.

[0120] Words relating to comparisons, measurements, and timings such as "at the time," "equivalent," "during," "complete," and the like, should be understood to mean "substantially at the time," "substantially equivalent," "substantially during," "substantially complete," and the like, where "substantially" means that such comparisons, measurements, and timings are practical to achieve the desired result implicitly or explicitly stated. Words relating to the relative positions of elements, such as "near," "proximate to," "adjacent to," and the like, are intended to mean close enough to substantially affect the interaction of the respective system elements. Other words of approximation similarly refer to conditions that, when so modified, are not necessarily considered absolute or complete, but would be considered close enough by one of ordinary skill in the art to warrant specifying the condition as existing. The extent to which the description may vary will depend on how significant the change is, and one of ordinary skill in the art would recognize the modified features as still having the desired properties and capabilities of the unmodified features.

[0121] The term "or combinations thereof" as used herein refers to all permutations and combinations of the listed items preceding the term. For example, "A, B, C, or combinations thereof" is intended to include at least one of A, B, C, AB, AC, BC, or ABC, as well as BA, CA, CB, CBA, BCA, ACB, BAC, or CAB, if the order is important in a particular context. Continuing with this example, combinations including repeats of one or more items or terms, such as BB, AAA, AB, BBC, AAABCCCC, CBBAAA, CABABB, etc., are expressly included. Those skilled in the art will understand that there is typically no limit to the number of items or terms in any combination, unless otherwise clear from the context.

[0122] All of the compositions and / or methods disclosed and claimed herein can be made and executed without undue experimentation in light of the present disclosure.The compositions and methods of the present disclosure are described in terms of preferred embodiments, but it will be apparent to those skilled in the art that various variations can be applied to the compositions and / or methods, and in the steps or sequence of steps of the methods described herein, without departing from the concept, spirit and scope of the present disclosure.All such similar substitutes and modifications that are apparent to those skilled in the art are deemed to be within the spirit, scope and concept of the disclosure as defined by the appended claims.

Claims

1. An array of waveguides, a substrate having a photographic medium; an interference pattern encoded within the photographic media, the interference pattern defining an array of substrate sites within the substrate, each substrate site comprising a plurality of substrate subsites; an optical element defining an array of optical element sites, each optical element site corresponding to a respective substrate site, each optical element site including a plurality of optical element subsite locations; the interference pattern is configured to propagate light to the optical element subsite locations of each of the optical element sites along optical propagation paths that extend through the substrate subsites of each substrate site, the optical propagation paths comprising a plurality of sets of optical propagation paths that extend through the same optical element site and the same substrate subsite of a corresponding substrate site; each set of light propagation paths extends from the optical elements away from the substrate in a unique direction and converges from different optical element subsite locations at the same optical element site to the same substrate subsite at the corresponding substrate site, the unique direction being determined by an angular orientation of a chief ray propagation path within each set of light propagation paths; whereby the array of optical element sites is configured to propagate light according to a four-dimensional bright field coordinate system having spatial coordinates defined by positions of the optical element sites and angular coordinates defined by the unique directions of the sets of light propagation paths of each optical element site; the optical element is an array of lenslets disposed at the optical element sites; An array of waveguides.

2. An array of waveguides, a substrate having a photographic medium; an interference pattern encoded within the photographic media, the interference pattern defining an array of substrate sites within the substrate, each substrate site comprising a plurality of substrate subsites; an optical element defining an array of optical element sites, each optical element site corresponding to a respective substrate site, each optical element site including a plurality of optical element subsite locations; the interference pattern is configured to propagate light to the optical element subsite locations of each of the optical element sites along optical propagation paths that extend through the substrate subsites of each substrate site, the optical propagation paths comprising a plurality of sets of optical propagation paths that extend through the same optical element site and the same substrate subsite of a corresponding substrate site; each set of light propagation paths extends from the optical elements away from the substrate in a unique direction and converges from different optical element subsite locations at the same optical element site to the same substrate subsite at the corresponding substrate site, the unique direction being determined by an angular orientation of a chief ray propagation path within each set of light propagation paths; whereby the array of optical element sites is configured to propagate light according to a four-dimensional bright field coordinate system having spatial coordinates defined by positions of the optical element sites and angular coordinates defined by the unique directions of the sets of light propagation paths of each optical element site; the optical element is an array of diffractive optical elements disposed at the optical element sites; An array of waveguides.

3. 3. The array of waveguides of claim 1 or 2, wherein the photographic medium comprises one of the materials selected from the group consisting of photographic emulsion, dichromated gelatin, photoresist, photothermoplastic, and photopolymer.

4. The array of waveguides of claim 2 , wherein each diffractive optical element propagates light according to a lens function.

5. 3. An array of waveguides as claimed in claim 2, wherein each diffractive optical element is subdivided into an array of subsite locations, each subsite location serving to deflect the light propagation path therethrough by a deflection angle.

6. 6. The array of waveguides of claim 5, wherein for all of the multiple sets of propagation paths associated with the diffractive optical element, the deflection angle of each subsite is selected to deflect light of each set of propagation paths incident on a first side of the optical element site in a unique direction.

7. 7. The array of waveguides of claim 1, wherein the interference pattern comprises a reflection hologram.

8. 7. The array of waveguides of claim 1, wherein the interference pattern comprises a transmission hologram.

9. A Holodeck energy directing system comprising an array of waveguides as described in any one of claims 1 to 8 and an illumination source array ("ISA") configured to provide illumination at each substrate site, the ISA being a collection of multiple illumination sources.

10. The Holodeck energy directing system of claim 9 , wherein the ISA comprises a plurality of illumination sources proximate to the substrate site.

11. 11. The Holodeck energy directing system of claim 10, wherein each interference pattern substrate site is encoded to direct a distribution of incident light from the corresponding light source along a respective set of the light propagation paths.

12. The Holodeck energy directing system of claim 11 , wherein the optical element site and the corresponding substrate site at least partially overlap.

13. The Holodeck energy directing system of claim 11 , wherein the optical element site and the corresponding substrate site have different dimensions.

14. 14. The Holodeck energy directing system of claim 11, wherein the optical element site and the corresponding substrate site of the ISA are concentric in a direction of light propagation, and the optical element site and the corresponding substrate site of the ISA are rectangular.

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