Holographic camera and encoder mask thereof

Abstract

A camera system and a corresponding encoder mask are presented. The camera system comprises: a detector array comprising a plurality of light sensitive pixels, an encoder mask comprising an array of a plurality of similar unit cells having selected encoder pattern, and a lens arrangement comprising one or more optical lenses positioned for imaging input light onto said encoder mask. Each of the plurality of similar unit cells carries an encoding pattern having at least first and second axes of symmetry. Alternatively, or additionally, the unit cells of said encoder mask are larger than a diffraction limited spot defined by the lens arrangement and the encoder mask is displaced from image plane defined by the lens arrangement thereby allowing for optical spot to cover a unit cell of said encoder mask.

Description

[0001] HOLOGRAPHIC CAMERA AND ENCODER MASK THEREOF

[0002] TECHNOLOGICAL FIELD

[0003] The present disclosure relates to configurations of a holographic camera, and specifically relates to a holographic camera utilizing selected configurations of encoder mask.

[0004] BACKGROUND

[0005] Optical imaging is a powerful tool for measurement, inspection, and imaging. Current optical measurement and imaging techniques can provide high-resolution data about the intensity of the input optical field. However, a great portion of the information carried by the optical field is lost in typical conventional imaging techniques that measure only the intensity of the field.

[0006] Various techniques utilizing holographic cameras include for example:

[0007] US 11,293,806, assigned to the assignee of the present application, describes an optical detection system for detecting data on the optical mutual coherence function of input field. The system comprising an encoder having similar unit cells, and an array of sensor cells located at a distance downstream of said unit cells with respect to a general direction of propagation of input light. The array defines a plurality of sub-array unit cells, each sub-array corresponding to a unit cell of the encoder, and each sub-array comprising a predetermined number M of sensor elements. The encoder applies predetermined modulation to input light collected by the system, such that each unit cell of said encoder directs a portion of the collected input light incident thereon onto sub-array unit cell corresponding therewith and one or more neighboring sub-array unit cells within a predetermined proximity region. The number M is determined in accordance with a predetermined number of sub-arrays unit cells within the proximity region. US 2023 / 029,930, assigned to the assignee of the present application, provides systems and methods for imaging, measuring an object, and characterizing a sample. An optical, speckle-based imaging system may comprise an illumination unit comprising at least one coherent light source to illuminate a sample; a collection unit for collecting input light from the sample, the collection unit consisting of an imaging optics and a wavefront imaging sensor; and a control unit coupled to the illumination unit and the collection unit for analyzing the input light and generating a speckle wavefront image, wherein the at least one coherent light source is to generate primary speckles in the sample or thereon, and the imaging optics is to capture a secondary speckle pattern induced by the illumination unit in the sample or thereon.

[0008] WO 2021 / 229,575, assigned to the assignee of the present application, provides systems and methods for digital optical aberration correction and spectral imaging. An optical system may comprise an optical imaging unit, to form an optical image near an image plane of the optical system; a wavefront imaging sensor unit located near the image plane, to provide raw digital data on an optical field and image output near the image plane; and a control unit for processing the raw digital data and the image output to provide deblurred image output, wherein the control unit comprises a storage unit that stores instructions and a processing unit to execute the instructions to receive the image input and the raw digital data of the optical field impinging on the wavefront imaging sensor and generate a deblurred image based on an analysis of the optical mutual coherence function at the imaging plane.

[0009] GENERAL DESCRIPTION

[0010] The is a need in the art for a holographic camera system having improved design providing high accuracy color reproduction and large depth dynamic range. The present disclosure provides a camera system and encoder mask for us in holographic camera, enabling collection of input wavefront and determining image pattern including wavefront structure and coherence data of the wavefront. The encoder mask of the present disclosure further enables reconstruction of spectral components of the collected wavefront. Providing accurate color reproduction of the collected wavefront. According to a broad aspect, the present disclosure provides a camera system, comprising:

[0011] (a) a detector array comprising a plurality of light sensitive pixels;

[0012] (b) an encoder mask comprising an array of a plurality of similar unit cells having selected encoder pattern;

[0013] (c) a lens arrangement comprising one or more optical lenses positioned for imaging input light onto said encoder mask; wherein each of said plurality of similar unit cells carries an encoding pattern having at least first and second axes of symmetry.

[0014] In some embodiments, the unit cells of the encoder carry the same encoder pattern between them. In some embodiments, the encoder pattern of the unit cells is equal for the unit cells.

[0015] According to some embodiments, the encoding pattern of said plurality of similar unit cells comprises a phase affecting pattern comprising one or more regions configured to provide phase variation of 2it or more between radiation components.

[0016] According to some embodiments, the encoding pattern of said plurality of similar unit cells comprises etched pattern having etching depth larger than wavelength of light for which the camera is designed for.

[0017] According to some embodiments, the camera system may be configured for wavefront imaging in visible and near IR wavelength range, the etched pattern having etching depth greater than 1.2 micrometer.

[0018] According to some embodiments, the encoding pattern of said similar unit cells is characterized by reflection symmetry about at least first and second different axes.

[0019] According to some embodiments, the encoding pattern of said similar unit cells is characterized by 180° rotation symmetry.

[0020] According to some embodiments, the arrangement of said plurality of similar unit cells defines a global encoding pattern having at least one additional symmetry beyond the at least first and second axes of symmetry of the unit cells.

[0021] According to some embodiments, the encoder mask is displaced from image plane defined by the lens arrangement, causing spot dilation. According to one other broad aspect, the present disclosure provides a camera system, comprising:

[0022] (a) a detector array comprising a plurality of light sensitive pixels;

[0023] (b) an encoder mask comprising an array of a plurality of encoders, each of said plurality of encoders comprises an array of a plurality of similar unit cells;

[0024] (c) a lens arrangement comprising one or more optical lenses positioned for imaging input light onto said encoder mask; wherein the unit cells of said encoder mask are larger than a diffraction limited spot defined by said lens arrangement and wherein said encoder mask is displaced from image plane defined by the lens arrangement thereby allowing for optical spot to cover a unit cell of said encoder mask.

[0025] In some embodiments, the unit cells of the encoder carry the same encoder pattern between them. In some embodiments, the encoder pattern of the unit cells is equal for the unit cells.

[0026] According to yet another broad aspect, the present disclosure provides an encoder mask, comprising a periodic arrangement of repeating unit cell, each of the repeating unit cells comprises an encoding pattern having at least first and second axes of symmetry.

[0027] According to some embodiments, the encoding pattern has at least first and second axes of associated with different symmetry about the first and second axes.

[0028] According to some embodiments, the repeating unit cells are similar unit cells. The similar unit cells generally carry an equal encoder pattern between them. The encoder pattern of the unit cells is typically equal between them.

[0029] According to some embodiments, the encoding pattern of said plurality of similar unit cells comprises a phase affecting pattern comprising one or more regions configured to provide phase variation of 2it or more between radiation components.

[0030] According to some embodiments, the encoding pattern of said plurality of unit cells comprises etched pattern having etching depth larger than wavelength of light for which the encoder is designed for.

[0031] According to some embodiments, the encoder mask may be configured for wavefront imaging in visible and near IR wavelength range, said etched pattern having etching depth greater than 1.2 micrometer. According to some embodiments, the said encoding pattern of said plurality of unit cells is characterized by reflection symmetry about at least first and second different axes.

[0032] According to some embodiments, the encoding pattern of said plurality of unit cells is characterized by 180° rotation symmetry.

[0033] According to some embodiments, the arrangement of said plurality of unit cells defines a global encoding pattern having at least one additional symmetry beyond the at least first and second axes of symmetry of the unit cells.

[0034] According to a further broad aspect, the present disclosure provides an optical detection system, comprising: an encoder mask having a plurality of similar unit cells; and an array of sensor cells located at a distance downstream of said unit cells with respect to a general direction of propagation of input light through the optical detection system; wherein said array of sensor cells defines a plurality of sub-array unit cells, each of the plurality of sub-array unit cells corresponding to a unit cell of said plurality of similar unit cells of the encoder, and each of the plurality of sub-array unit cells comprising a predetermined number M of detector elements; wherein encoding pattern of each of said plurality of similar unit cells is characterized by at least first and second axes of symmetry.

[0035] According to some embodiments, the encoding pattern of each of said plurality of similar unit cells may be characterizes by first and second axes of symmetry having different symmetrical pattern there along.

[0036] According to some embodiments, the encoder mask is configured to apply predetermined modulation to input light collected by the optical detection system, such that each of the plurality of similar unit cells of said encoder expands a portion of the collected input light incident thereon onto one of the plurality of sub-array unit cells corresponding therewith and one or more neighboring sub-array unit cells within a predetermined proximity region; and

[0037] According to some embodiments, the predetermined number M is determined in accordance with a predetermined number of sub-arrays unit cells within the predetermined proximity region. In some embodiments, the predetermined number M of detector elements may be 9 or 16 or 25.

[0038] BRIEF DESCRIPTION OF THE DRAWINGS

[0039] In order to better understand the subject matter that is disclosed herein and to exemplify how it may be carried out in practice, embodiments will now be described, by way of non-limiting example only, with reference to the accompanying drawings, in which:

[0040] Fig. 1 schematically illustrates a camera system according to some embodiments of the present disclosure;

[0041] Figs. 2A to 2D exemplify four encoding patterns for unit cell of the encoder mask according to some embodiments of the present disclosure;

[0042] Figs. 3A to 3C exemplify symmetry of encoding pattern within unit cell of the encoder (Fig. 3A), symmetry effects on detector elements of respective sub-array of the detector array (Fig. 3B), and global symmetry effects associated with neighboring subarrays of the detector array (Fig. 3C); and

[0043] Figs. 4A to 4C exemplify optical arrangement of the camera system according to some embodiments of the present disclosure.

[0044] DETAILED DESCRIPTION OF EMBODIMENTS

[0045] As indicated above, the present disclosure provides a camera system, encoder mask and respective technique, capable of providing data indicative of light field properties at a desired spatial resolution. Reference is made to Fig. 1 schematically illustrating a camera system 100, or holographic camera system, configured for detection of light field phase, coherence, intensity data, and optionally spectral data. The camera system 100 includes a lens arrangement 110, an encoder mask 120 located at a selected distance LI downstream of the lens arrangement 110, and a detector array 140 located at predetermined distance L2 downstream of the encoder 120 with respect to general direction of radiation propagation. The encoder 120 may be formed as a separate unit from the detector array 140, or it may be monolithically integrated with the detector array 140, and even be part of the process stack used to manufacture the sensor array, e.g., using metallization process steps, and / or process steps similar to those used in manufacturing micro-lens arrays typically used to improve pixel fill-factors in sensor arrays.

[0046] Detector array 140, includes a plurality of detector elements (pixels), and configured such that selected sub-arrays of the detector elements are associated with respective unit cells of the encoder mask 120. Generally, a number of detector elements associated with each unit cell of the encoder mask may be selected to be 4, 9, 16 or any other selected number M. The number of detector elements associated with each unit cell of the encoder mask may determine resolution of phase and / or coherence data obtainable by the camera system 100.

[0047] Camera system 100 may also include a control system 500 configured for receiving data on intensity distribution of collected radiation from the detector array 140, and for processing the received data in accordance with pre-stored data on encoding pattern and arrangement of the encoder mask 120 to determine data about intensity, phase, coherence distribution, and / or spectral components of collected light. The control system may include one or more processors 550 and a memory 600, as well as input and output interface enabling input and output communication and possible user interface, which are not specifically shown.

[0048] The control system 500 may be integral with camera system 100 or separated therefrom. In some embodiments, the control system 500 may be remote from camera system 100 or it may utilize remote, or cloud processing of data collected by the detector array 140. In such configurations, camera system 100 may include a communication module configured for transmitting data about the pattern of the encoder 120 and intensity distribution data collected by the detector array 140 to the control system 500 for processing.

[0049] Generally, the at least one processor 550 and memory 600 of control system 500 provide a processor and memory circuitry, operatively connected to an input / output interface. The PMC is configured to provide processing necessary for operating the camera system 100 as further detailed below and comprises a processor 550 and a memory 600. The processor 550 of PMC can be configured to execute several functional modules in accordance with computer-readable instructions implemented on a non-transitory computer-readable memory comprised in the PMC. Such functional modules are comprised in the PMC.

[0050] Generally, in some embodiments, control system 500, and / or PMC thereof, is configured to receive data on intensity distribution collected by the detector array 140 and process the data in accordance with data on pattern of encoder mask 120, to determine wavefront image data of a scene or one or more objects being imaged. The wavefront data may include one or more of mutual coherence function, wavefront shape / structure, spectral components, and / or phase distribution data of the collected radiation field.

[0051] In this connection, camera system 100 is configured to provide imaging of a scene, (e.g., collected wavefront) onto, or in vicinity to, the encoder mask 120. The encoder mask 120 affects the radiation components transmitted therethrough by expanding radiation portions (e.g., by diffraction and / or refraction) to impinge on detector elements associated with the unit cell of the encoder mask 120 as well as to detector element associated with neighboring unit cell of the encoder mask 120. To this end, the pattern of the similar unit cells of encoder mask 120 may be configured to expand radiation components to impinge within a selected proximity region, which may be determined in part by a number of detector elements associated with each unit cell of the encoder 120.

[0052] Expansion of light components impinging on each unit cell onto a proximity region including sub-arrays of detector elements that are associated with neighboring unit cells of the encoder 120 provides for interference of light components. This enables reconstruction of phase and / or coherence data of the collected wavefront. Additionally, as described in more detail further below, selected symmetry properties of the encoder mask 120 enable reconstruction of spectral components, e.g., RGB, RGB+IR or other selected spectral bands, within the collected wavefront. Further additionally, variations from the symmetry properties of the encoder mask provides data on depth variation enabling reconstruction of three-dimensional image of based on the collected light. In this connection the term “light” as used herein should be understood broadly as relating to electromagnetic radiation of one or more selected wavelength ranges. The camera system of the present disclosure may generally be configured for operating in visible or visible and infrared wavelength ranges. However, in some embodiments, the camera system may be configured for operating in one or more selected infrared wavelength ranges and may provide for differentiating between selected spectral bands within a selected wavelength range such as infrared, UVA, UVB, UVC, X-ray wavelength ranges etc.

[0053] In some embodiments, control system 500 carries pre-stored data indicative of a selected number of fundamental response functions, indicating intensity of light passing through a unit cell of the encoder 120. The fundamental response functions may include data on amplitude and phase distribution of light propagating from the encoder mask 120 toward the detector array 140. The data about fundamental response function may be pre- processed for a set of ''coherence basis junctions’' acting as set of basis vectors that span the space of possible mutual coherence matrices to be collected by the camera system 100. The coherence basis functions may be complemented by a set of “ intensity basis functions", which is a set of predetermined intensity patterns, where each such intensity pattern is given by the intensity of the optical field of each corresponding coherence basis function as it propagates through the encoder mask 120 and impinges on the detector array 140. In some implementations, the coherence basis functions, and corresponding intensity basis functions may be pre-computed or pre-measured and stored in the memory 600.

[0054] In some embodiments, the present disclosure utilizes selected symmetry properties of the encoder mask 120 pattern to enhance imaging conditions of camera system 100. More specifically, according to some embodiments, encoder mask 120 includes an arrangement of a plurality of unit cells having similar encoding pattern, where the encoding pattern of the unit cells has a selected symmetry property about one or more axes. As indicated above, symmetry properties of the encoding pattern within the unit cells of the mask 120 provide differentiation in light pattern collected by the detector elements of detector array 140. This allows the camera system 100 to reconstruct image data including data on one or more, typically three or four, different spectral bands of the collected light. Further, variation from the symmetry conditions enables reconstruction of depth information and generating a three-dimensional image data indicative of a scene based on collected wavefront.

[0055] In this connection, reference is made to Figs. 2A to 2D exemplifying four encoding configurations of a single unit cell 122 according to some embodiments of the present disclosure. Figs. 2A and 2B exemplify a rectangular encoding pattern having reflection symmetries about first and second axes, Fig. 2C exemplifies a second encoding pattern having 180° rotation symmetry, and Fig. 2D exemplifies an additional rectangular encoding pattern having reflection symmetry about first and second diagonals.

[0056] More specifically, Figs. 2A to 2D exemplify encoding pattern of a unit cell 122, where a plurality of similar unit cells 122 may be arranged together to form encoder mask 120. The exemplified pattern includes selected number of regions R1 to R4 in Figs. 2A, 2B and 2D, and R1 to R5 in Fig. 2C, each region may relate to a selected phase affecting region. For example, in some embodiments, each region relates to a selected etching depth, where regions R1 to R5 indicate etching depth different than region Rl. This is while regions Rl to R5 may be different or similar between them. Generally, the encoding pattern may be any type of phase and / or amplitude affecting pattern and may cause expansion of light components by diffraction and / or refraction of light. In some embodiments the phase pattern may be formed by etching of selected depth into material of the encoder mask, in some embodiments, the phase pattern may be formed by metallization, doping, metasurfaces, and / or coating of selected regions of the encoder mask 120. For simplicity, the phase pattern is described herein as relating to etching, however, it should be noted that the present disclosure relates to any other phase affecting pattern.

[0057] As indicated above, symmetry properties of the encoding of the unit cells 122 enables spectral reconstruction and extraction of depth information from the collected wavefront. In this connection, Fig. 2A to 2D exemplify symmetry axes Al and A2, characterizing symmetry properties of the encoding pattern of the unit cell 122. As shown, the pattern of Figs. 2A and 2B is characterized by reflection symmetry about axes Al and A2, where Fig. 2A exemplifies variation in symmetry between axes Al and A2, while Fig. 2B exemplifies similar symmetry properties with respect to axes Al and A2. The pattern of Fig. 2C is characterized by 180° rotation symmetry. The pattern of Fig. 2D is characterized by reflection symmetry about diagonal axes Al and A2.

[0058] As indicated above, regions R1 to R5 exemplified in Figs. 2A to 2D indicate different phase affecting region. Variation in phase of light components passing through the encoder provide for expansion of radiation impinging thereon into a selected proximity region on the detector array and generate selected diffraction pattern typically associated with wavelength of the light components. In some embodiments of the present disclosure, phase difference between regions R2 to R5 and region R1 may be associated with 2it phase variation or greater. For example, in the case of phase affecting regions formed by etching, the etching depth may be larger than wavelength of radiation for which the encoder mask 120 or the camera system 100 is configured. For example, in a camera system configured for wavefront imaging within visible and near infrared wavelength range, the etching depth may be selected to be within a range between 1 micrometer and 3 micrometers. In some examples, the etching depth may be selected as 1.2 to 1.7 micrometers.

[0059] As indicated, the selected phase affecting pattern, e.g., formed by an etching pattern having selected depth, of the encoder mask 120 may provide phase variation that is generally greater than 2it for wavelength range for which the encoder, or camera system, is designed for. This provides for phase affecting pattern that induced effective interference for a broad spectral range. The variation in interference and diffraction of radiation of different wavelengths enables the camera system of the present disclosure to obtain spectral data of collected wavefront. By providing phase affecting pattern of the encoder, providing interference effects to broad spectral range, the camera system of the present disclosure may determine spectral components of input radiation, without the need for spectral filters of the detector array.

[0060] Additionally, design of the encoding pattern of unit cells 122, and replication of the unit cells in an array forming the encoder mask, provide selected diffraction properties, and cross-talk between light components impinging on different unit cells 122. The camera system utilizes cross talk between light components passing through neighboring unit cells of the encoder and generating interference on the detector array to determine phase relation and coherence matrix of the collected light. Additionally, symmetrical properties of the encoding patern of the different unit cells enables selective reconstruction of the collected image and determining spectral components of the collected light. More specifically, the encoder design having different symmetry properties with respect to different axes Al and A2, enables determining spectral components of the collected light to reconstruct collected image including intensity, coherence matrix, and selected spectral bands such as RGB spectral bands. The exemplary unit cell encodings illustrated in Figs. 2A to 2D provide reflection or rotation symmetry, such that encodings of Figs. 2A, 2B and 2D indicate reflection symmetry about first and second axe resulting in variation in interference pattern collected by the detector along the respective axes. The example of Fig. 2C illustrates rotation symmetry of 180°, providing corresponding variation in interference pattern collected by the detector array with respect to axes Al and A2 projected on the detector plane.

[0061] More specifically, due to variation in diffraction properties of light components in accordance with wavelength of light, variation in symmetry properties of the encoding patern in the unit cell 122 cause respective diffraction of light components of different wavelengths. As a result, different detector elements of the detector sub-array associated with a given unit cell 122 of the encoder provide data indicative of respective spectral components of the collected wavefront. Accordingly, using a selected number of different symmetry axes (e.g., axes Al and A2) enable reconstruction of the collected wavefront using corresponding number of spectral bands. For example, the encoding pattern of Fig. 2B has similar symmetry about axes Al and A2, and can thus provide image reconstruction using RGB spectral components. This is while the encoding paterns of Figs. 2A, 2C or 2D have different symmetry about axes Al and A2, and can support image reconstruction with an additional spectral band such as infrared.

[0062] As indicated, additional symmetry properties may be used to reconstruct further spectral bands, including e.g., RGB+IR spectral components of image data. Further variation in light collection along a selected axis of symmetry may be used for reconstruction of depth information. Figs. 3A to 3C exemplify the relation between symmetry of encoding pattern of a unit cell in Fig. 3A, arrangement of detector elements associated with a respect unit cell in Fig. 3B, and global arrangement of detector elements associated with a plurality of unit calls of the encoder mask in Fig. 3C.

[0063] Fig. 3A illustrates a unit cell 122 of the encoder mask having encoding pattern. In this example, the encoding pattern has symmetry for reflection about vertical and horizontal axes Al and A2, and also has symmetry for reflection about diagonal axes DI and D2. In this example, the encoding pattern is formed of main region R1 and phase affecting regions R2 and R’2 arranged within the unit call 122. Regions R2 and R’2 may be similar or different, determining symmetry levels and accordingly number of spectral bands that can be reconstructed in the wavefront data. Fig. 3B exemplifies an arrangement of detector elements 144 forming a sub-array 142 of detector elements, associated with a unit cell 122 of the encoder. As a result of symmetry of the encoder illustrated in Fig. 3A, illumination pattern collected by the sub-array 142 of detector elements 144 generally has corresponding symmetry. Accordingly, neglecting for this explanation the cross talk between unit cells, the detector elements 144 of the sub-array 142 collect light components with symmetrical properties that are generally similar to those of the encoded unit cell. In this example, the detector elements are marked by pixel relations including central pixel Pl, horizontally arranged pixels P2, vertically arranged pixels P’2, diagonal pixels P3 and P’3. More specifically, in case where regions R2=R’2 in Fig. 3A, detector elements are expected to have similar symmetry providing that P2=P’2 and / or P3=P’3.

[0064] Pixels P2 and P’2 relate to symmetry of the encoder along vertical and horizontal axes Al and A2 and may be similar or different in accordance with symmetry of the encoding of the unit cell 122, and similarly for diagonal regions P3 and P’3. In the example of Fig. 3A the encoding pattern has symmetry for reflection about vertical and horizontal axes Al and A2, and may have similar symmetry if regions R2 and R’2 are of equal dimensions, or both diagonals DI and D2, light components collected by pixels P2 and P’2 (or P3 and P’3) are expected to be similar. Generally maintaining common symmetry along the horizontal and vertical axes Al and A2, or common symmetry about the two diagonal axes DI and D2 may simplify reconstruction processing, but typically provides data on reduced number of spectral bands, while different symmetry about these axes may enable wavefront reconstruction with data on additional spectral bands. For example, if symmetry of the encoder provides that P2=P’2 and P3=P’3 (i.e. 90° rotation symmetry of the encoder), the camera system can provide spectral data to obtain RGB image, this is while if P2 is different than P’2, and P3 is different than P’3, as resulting from the encoder examples of Fig. 2A to 2D, the camera system can also determine infrared spectral band in wavefront reconstruction.

[0065] This expected symmetry in detection of light components may be further used in reconstruction of collected wavefront including intensity, coherence matrix and spectral components. More specifically, as detector sub-arrays associated with the different unit cells of the encoder mask have cross talk between them, interference of light components causes variation between the detector array allowing to reconstruct the shape of a collected wavefront. Fig. 3C exemplifies an arrangement of detector array 140 including a number of sub-arrays 144 associated with a number of unit cells of the encoder. Detector elements 142 associated with common symmetry such as P2, P’2, P3 and P’3 are marked in Fig. 3C by different patterns. In this example, filling pattern of the detector elements exemplifies a situation of different symmetry for reflection about Al an A2 axes, i.e., P2 P’2 Fig. 3C also illustrates symmetry within sub-array 144 marked by LI and symmetry relation shared by neighboring sub-arrays marked by L2. The symmetry conditions LI enable wavefront reconstruction providing RGB and / or RGB+IR in accordance with symmetry variations. Additionally, variation of collected intensity from expected symmetry condition can be used for reconstruction of depth data of the collected wavefront. This enables to determine three-dimensional structure of an object, or a scene based on reconstruction of the collected wavefront. More specifically, variation in intensity collected between pixels along a common symmetry axis may be used to determine edges, and depth variation in reconstruction of collected wavefront data. For example, as a result of depth variation, intensity collected at the right P2 pixel may differ from the intensity collected at the left P2 pixel.

[0066] It should be understood that the actual intensity collected by each pixel may relate also to light components passing through neighboring unit cells of the encoder mask. Accordingly, depth information may be obtained in image reconstruction based on variation from symmetry conditions within a number of pixels. This is exemplified in Fig. 3C using path L2 associated with pixels of a number (e.g., four) of sub-arrays associated with neighboring unit cells of the encoder. Variation in collected intensity along path L2, or variation in collected intensity from expected symmetry determined by encoding pattern of the mask 120 thus indicates depth information and may be used for reconstruction of three-dimensional data of the object / scene being imaged.

[0067] Generally, according to some embodiments of the present disclosure, a field of view of the camera system 100 may be determined in accordance with f-number (f / #) of the lens arrangement 110. Additionally, the f-number may also determine size of a diffraction limited spot / pixel of the camera system. In holographic camera system 100 of the present disclosure, image resolution and / or sampling ratio can be determined by a relation between diffraction limited spot size and unit cell 122 size. According to some embodiments, the camera system 100 may operate with a size of unit cell 122 determined to be larger than diffraction limited spot of the lens arrangement 110, thereby providing certain under sampling of the collected wavefront. Additionally, arrangement of the camera system, and positions of the encoder mask with respect to focal length of the lens arrangement may be used to generate selected spot dilation, improving wavefront collection properties.

[0068] For example, reference is made to Figs. 4A and 4C exemplifying arrangement of camera system 100 including lens arrangement 110, encoder mask 120 and detector array 130 with respect to focal plane of the lens arrangement 110. As shown, in Fig. 4A the encoder mask 120 is placed at a focal plane, or image plane for a selected focusing conditions of lens arrangement 110. In Fig. 4B, the encoder mask 120 is displaced from the focal / image plane and is placed at a location f+A, being further from focal plane f of the lens arrangement 110. Additionally, in Fig. 4C, the encoder mask 120 is located at a location f-A, being closer to the lens arrangement 110 than the focal plane f. Displacement of the encoder mask with respect to the focal plane f provides selected spot dilation and can improve and / or simplify wavefront reconstruction quality.

[0069] In this connection, it should be noted that lens arrangement 110 may typically include a focusing arrangement capable of varying optical focusing conditions. The term focal plane relates to imaging of objects located at large distance (infinity) and should be understood as relating to image plane for a selected imaging conditions. More specifically, the lens arrangement 110 may be used to adjust focal length thereof to bring the image plane of a selected imaging conditions onto the plane marked f in Figs. 4A to 4C.

[0070] Accordingly, the present disclosure provides a camera system, operable as a holographic camera system and capable of generating output data indicative of phase and / or coherence of a collected wavefront, and an encoding mask for use in such camera system. The camera system utilizes symmetry conditions of the encoding mask to determine a selected number of spectral bands within collected wavefront and may utilize variation from the symmetry conditions for determining depth information of the collected wavefront.

[0071] It is to be noted that the various features described in the various examples can be combined according to all possible technical combinations.

[0072] It is to be understood that the invention is not limited in its application to the details set forth in the description contained herein or illustrated in the drawings. The invention is capable of other examples and of being practiced and carried out in various ways. Hence, it is to be understood that the phraseology and terminology employed herein are for the purpose of description and should not be regarded as limiting. As such, those skilled in the art will appreciate that the conception upon which this disclosure is based can readily be utilized as a basis for designing other structures, methods, and systems for carrying out the several purposes of the presently disclosed subject matter.

[0073] Those skilled in the art will readily appreciate that various modifications and changes can be applied to the examples of the invention as hereinbefore described without departing from its scope, defined in and by the appended claims.

Claims

CLAIMS:

1. A camera system, comprising:(a) a detector array comprising a plurality of light sensitive pixels;(b) an encoder mask comprising an array of a plurality of similar unit cells, each having a selected encoding pattern; and(c) a lens arrangement comprising one or more optical lenses positioned to image input light onto the encoder mask; wherein each of the plurality of similar unit cells carries an encoding pattern with at least first and second axes of symmetry.

2. The camera system of claim 1, wherein the encoding pattern of each of the plurality of similar unit cells comprises a phase-affecting pattern having one or more regions configured to provide a phase variation of 2it or more between radiation components.

3. The camera system of claim 1 or 2, wherein the encoding pattern of each of the plurality of similar unit cells comprises an etched pattern with an etching depth greater than the wavelength of light for which the camera is designed.

4. The camera system of claim 3, configured for wavefront imaging in the visible and near-infrared (IR) wavelength range, wherein the etched pattern has an etching depth greater than 1.2 micrometers.

5. The camera system of any one of claims 1 to 4, wherein the encoding pattern of each similar unit cell is characterized by reflection symmetry about at least two different axes.

6. The camera system of any one of claims 1 to 5, wherein the encoding pattern of each similar unit cell is characterized by 180-degree rotational symmetry.

7. The camera system of any one of claims 1 to 6, wherein the arrangement of the plurality of similar unit cells defines a global encoding pattern having at least one additional symmetry beyond the first and second axes of symmetry of the unit cells.

8. The camera system of any one of claims 1 to 7, wherein the encoder mask is displaced from an image plane defined by the lens arrangement, causing spot dilation.

9. A camera system, comprising:(a) a detector array comprising a plurality of light sensitive pixels;(b) an encoder mask comprising an array of a plurality of encoders, each of said plurality of encoders comprises an array of a plurality of similar unit cells;(c) a lens arrangement comprising one or more optical lenses positioned for imaging input light onto said encoder mask; wherein the unit cells of said encoder mask are larger than a diffraction limited spot defined by said lens arrangement and wherein said encoder mask is displaced from image plane defined by the lens arrangement thereby allowing for optical spot to cover a unit cell of said encoder mask.

10. An encoder mask, comprising a periodic arrangement of repeating unit cells, each of the repeating unit cells including an encoding pattern with at least first and second axes of symmetry.

11. The encoder mask of claim 10, wherein the encoding pattern has different symmetries associated with the first and second axes.

12. The encoder mask of claim 10 or 11, wherein the repeating unit cells are similar unit cells.

13. The encoder mask of any one of claims 10 to 12, wherein the encoding pattern of the similar unit cells comprises a phase-affecting pattern having one or more regions configured to provide a phase variation of 2it or more between radiation components.

14. The encoder mask of any one of claims 10 to 13, wherein the encoding pattern of the similar unit cells comprises an etched pattern with an etching depth greater than a wavelength of light for which the encoder mask is designed.

15. The encoder mask of claim 14, configured for wavefront imaging in the visible and near-infrared (IR) wavelength range, wherein the etched pattern has an etching depth greater than 1.2 micrometers.

16. The encoder mask of any one of claims 10 to 15, wherein the encoding pattern of the similar unit cells is characterized by reflection symmetry about at least two different axes.

17. The encoder mask of any one of claims 10 to 16, wherein the encoding pattern of the similar unit cells is characterized by 180° rotation symmetry.

18. The encoder mask of any one of claims 10 to 17, wherein the arrangement of the similar unit cells defines a global encoding pattern having at least one additional symmetry beyond the first and second axes of symmetry of the unit cells.

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