Polarization camera system and optical arrangement thereof

Abstract

A camera system and a corresponding optical module are described. The camera system comprising at least one detector array comprising a plurality of optical radiation sensitive pixels, an optical arrangement configured for imaging a scene onto a plane defined by the at least one detector array, and at least one polarization filter array comprising a plurality of polarization filter cells, each polarization filter cell is associated with a corresponding pixel of the detector array. The optical arrangement comprises at least a first imaging optics and a second optical relay arrangement, and the at least one polarization filter array is located at an image plane of the first imaging optics, and wherein the second optical relay is configured to relay radiation from the at least one polarization filter array to the at least one detector array.

Description

[0001] POLARIZATION CAMERA SYSTEM AND OPTICAL ARRANGEMENT

[0002] THEREOF

[0003] TECHNOLOGICAL FIELD

[0004] The present disclosure relates to polarization camera systems and to optical arrangement enabling polarization detection in camera systems.

[0005] BACKGROUND

[0006] Polarization is a fundamental property of light, which describes the orientation of oscillations of the electromagnetic waves. While conventional imaging systems capture color (wavelength) and intensity information, polarization imaging enables detection and analysis of the polarization states of collected radiation. This capability unveils additional information on the interaction with materials and surfaces, offering insights that are invisible to standard imaging techniques.

[0007] Polarization imaging systems typically consist of a camera equipped with polarization filters. The use of polarization filters enables such polarization imaging systems to analyze light waves oscillating in one or more specific directions. Further, such systems can at times measure several polarization parameters, including e.g., the degree of polarization, angle of polarization, etc., providing detailed insights about the scene or object under observation.

[0008] US9,829,384 Describes a long wave infrared imaging polarimeter (LWIP) is disclosed including a pixilated polarizing array (PPA) in close proximity to a microbolometer focal plane array (MFPA), along with an alignment engine for aligning and bonding the PPA and MFPA and method for assembly.

[0009] US10, 031,026 describes a short wave infrared polarimeter comprising a pixelated polarizer array and an Indium-Gallium-Arsenide (“InGaAs”) focal plane array. The short wave infrared polarimeter optionally includes a micro-lens array and / or an aperture layer. GENERAL DESCRIPTION

[0010] As indicated above, polarization imaging systems enable collection of additional information on a scene over what is possible using collection of images that only includes light intensity pattern. Polarization pattern of radiation collected from a scene can provide information associated with types of surface or materials, textures and / or orientation of objects in a scene.

[0011] In various polarization imaging systems, a polarization filter array is directly placed on top of detector array of the imaging system, to filter light of selected polarization orientation for each pixel of the detector array. Such configuration may be suitable for certain wavelength ranges. However, in accordance with detector parameters, a polarization focal plane array (polarization FPA) may be very expensive, and may require specifically made arrangement of detector pixels, adapted for detecting light of selected wavelength range and polarization.

[0012] The present disclosure provides an imaging system and an optical module configured as an addon for an imaging system. The optical module is configured to provide the associated imaging system with the ability to collect polarization data while avoiding the high costs associated with a polarization FPA. To this end the present disclosure utilizes at least one polarization filter array and an optical relay arrangement configured to relay radiation transmitted through the polarization filter array onto detector array of an associated imaging system.

[0013] Generally, the optical module is adapted to connect between an imaging system and a lens arrangement. The optical module comprises at least one polarization filter array comprising a plurality of polarization filter cells having at least two different orientations, and an optical relay module comprising one or more optical elements. The optical module may further comprise first and second connection adaptors. The first connection adaptor is configured for connecting the optical module to a respective imaging system. The optical relay module is configured to relay radiation from the at least one polarization filter array onto detector array of the imaging system, such that the polarization filter array and the detector array of the imaging system are on conjugated optical planes. The second connection adapter is configured for connecting the optical module to an imaging lens arrangement, having physical arrangement placing the at least one polarization filter array at imaging plane with respect to the imaging lens arrangement. Additionally, the polarization filter array is aligned with respect to optical axis of the optical relay module and that of the respective imaging system, to provide correspondence between unit cells of the polarization filter array and that of the detector array of the imaging system. In some embodiments such correspondence indicate that light transmitted through a unit cell of the polarization filter array falls onto a corresponding detector of the detector array. In some other embodiments, such correspondence indicate that light transmitted through a unit cell of the polarization filter array, falls onto a group of a selected number of detectors of the detector array.

[0014] Thus, according to a broad aspect, the present disclosure provides a camera system comprising: at least one detector array comprising a plurality of optical radiation sensitive pixels; an optical arrangement configured for imaging a scene onto a plane defined by the at least one detector array; at least one polarization filter array comprising a plurality of polarization filter cells, each polarization filter cell is associated with a corresponding pixel of the detector array; wherein the optical arrangement comprises at least a first imaging optics and a second optical relay arrangement, and the at least one polarization filter array is located at an image plane of the first imaging optics, and wherein the second optical relay is configured to relay radiation from the at least one polarization filter array to the at least one detector array.

[0015] According to some embodiments, the at least one polarization filter array and the at least one detector array are positioned in conjugated optical planes.

[0016] According to some embodiments, the at least one polarization filter array comprises a plurality of polarization filter cells, comprising polarization filter cells in at least two orthogonal orientations.

[0017] According to some embodiments, the at least one polarization filter array comprises a plurality of polarization filter cells, comprising the polarization filter cells in at least two orthogonal orientations, and at least two intermediate polarization orientations.

[0018] According to some embodiments, the at least one polarization filter array comprises a plurality of polarization filter cells, comprising horizontal polarization filter cells, vertical polarization filter cells, 45° orientated polarization filter cells and -45° oriented polarization filter cells.

[0019] According to some embodiments, the at least one polarization filter array comprises an arrangement of sub-array units, and wherein each sub-array unit comprises an arrangement of a horizontal polarization filter cell, a vertical polarization filter cell, a 45° orientated polarization filter cell and a -45° oriented polarization filter cell.

[0020] According to some embodiments, the at least one polarization filter array comprises an arrangement of sub-array units, and wherein each sub-array unit comprises an arrangement of polarization filter cells having polarization orientation of ±30°, ±60°, 0°, and 90°.

[0021] According to some embodiments, the filter cells of the at least one polarization filter array are arranged at varying distances between them in accordance with spatial optical distortion of the second optical relay arrangement.

[0022] According to some embodiments, the at least one polarization filter array comprises at least one opaque region thereby enabling alignment of the at least one polarization filter array with respect to pixel arrangement of the at least one detector array.

[0023] According to some embodiments, the second optical relay arrangement is characterized by magnification between 0.5 and 1.5. In some embodiments, the second optical relay arrangement has magnification of m=l.

[0024] According to some embodiments, the second optical relay arrangement is characterized by numerical aperture AN in a range between 0.7 and 0.9.

[0025] According to some embodiments, the camera system may be configured for operating in infrared radiation spectrum.

[0026] According to some embodiments, the camera system may be configured for collecting optical radiation within a wavelength range between 7 and 14 micrometers.

[0027] According to some embodiments, the camera system may be configured for collecting optical radiation within a wavelength range between 3 and 5 micrometers.

[0028] According to some embodiments, the optical arrangement is configured for passive thermalization within a temperature range between -40°C and 60°C.

[0029] According to one other broad aspect, the present disclosure provides an optical module configured to be attached to an imaging system and comprising an optical relay arrangement and a polarization filter array; the optical relay arrangement comprises one or more optical elements and is configured to relay optical radiation transmitted through the polarization filter array onto a detector array of the imaging system; the polarization filter array comprises a plurality of polarization filter cells having at least two different polarization orientations; wherein the optical module is configured such that the polarization filter cells correspond to pixels of a detector array of the corresponding imaging system such that each pixel collects radiation associated with a respective polarization filter cell.

[0030] According to some embodiments, the optical module may further comprise a case having first and second connection adaptors, the first connection adaptor is configured for connecting the optical module to the respective imaging system and the second connection adapter is configured for connecting the optical module to an imaging lens arrangement.

[0031] According to some embodiments, the optical module may be configured for connecting to a lens arrangement to provide imaging of collected radiation onto the polarization filter array.

[0032] According to some embodiments, the polarization filter array is positioned in a conjugated optical plane with respect to the detector of the imaging system.

[0033] According to some embodiments, the polarization filter array comprises a plurality of polarization filter cells, comprising polarization filter cells in at least two orthogonal orientations.

[0034] According to some embodiments, the polarization filter array comprises a plurality of polarization filter cells, comprising the polarization filter cells in at least two orthogonal orientations, and at least two intermediate polarization orientations.

[0035] According to some embodiments, the polarization filter array comprises a plurality of polarization filter cells, comprising horizontal polarization filter cells, vertical polarization filter cells, 45° orientated polarization filter cells and -45° oriented polarization filter cells.

[0036] According to some embodiments, the polarization filter array comprises an arrangement of sub-array units, and wherein each sub-array unit comprises an arrangement of a horizontal polarization filter cell, a vertical polarization filter cell, a 45° orientated polarization filter cell and a -45° oriented polarization filter cell.

[0037] According to some embodiments, the polarization filter array comprises an arrangement of sub-array units, and wherein each sub-array unit comprises an arrangement of polarization filter cells having polarization orientation of ±30°, ±60°, 0°, and 90°.

[0038] According to some embodiments, filter cells of the polarization filter array are arranged at varying distances between them in accordance with spatial optical distortion of the optical relay arrangement. According to some embodiments, the polarization filter array comprises at least one opaque region thereby enabling alignment of the polarization filter array with respect to pixel arrangement of the at least one detector array.

[0039] According to some embodiments, the optical relay arrangement is characterized by magnification between 0.5 and 1.5.

[0040] According to some embodiments, the optical relay arrangement has magnification of m=l.

[0041] According to some embodiments, the optical relay arrangement is characterized by numerical aperture AN in a range between 0.7 and 0.9.

[0042] According to some embodiments, the optical module may be configured for operating in infrared radiation spectrum.

[0043] According to some embodiments, the optical module may be configured for collecting optical radiation within a wavelength range between 7 and 14 micrometers.

[0044] According to some embodiments, the optical module may be configured for collecting optical radiation within a wavelength range between 3 and 5 micrometers.

[0045] According to some embodiments, the optical arrangement is configured for passive thermalization within a temperature range between -40°C and 60°C.

[0046] According to some embodiments, the polarization filter array comprises a plurality of polarization filter cells, comprising horizontal polarization filter cells, vertical polarization filter cells, 45° orientated polarization filter cells and -45° oriented polarization filter cells.

[0047] BRIEF DESCRIPTION OF THE DRAWINGS

[0048] 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:

[0049] Fig. 1 schematically illustrates a polarization camera system according to some embodiments of the present disclosure; Figs. 2A to 2C exemplify three configurations of polarization filter array, Fig. 2A exemplifies a polarization filter array with two orthogonal polarization filter cells, Fig. 2B exemplifies a polarization filter array having polarization filter cells with four different orientations, and Fig. 2C exemplifies a polarization filter array having polarization filter cells with six different orientations and blocking regions;

[0050] Fig. 3 exemplifies operation of a polarization filter;

[0051] Fig. 4 exemplifies an optical arrangement of a camera system according to some embodiments of the present disclosure and light ray tracing through the camera system;

[0052] Fig. 5 exemplifies an optical arrangement of an optical module according to some embodiments of the present disclosure; and

[0053] Fig. 6 exemplifies a patterned arrangement of clusters of polarization filter cells in accordance with optical distortions according to some embodiments of the present disclosure.

[0054] DETAILED DESCRIPTION OF EMBODIMENTS

[0055] As indicated above, the present disclosure provides a camera system for providing polarization data on optical radiation collected from a scene, and a corresponding optical module configured to be attached to an imaging (camera) system. Reference is made to Fig. 1 schematically illustrating an imaging system (camera system) 100 configured according to some embodiments of the present disclosure. Camera system 100 includes an optical arrangement, at least one detector array 122, typically held within housing 120, and at least one polarization filter array 112. According to the present disclosure, the at least one polarization filter array 112 is located at a selected distance from the at least one detector array 122. Additionally, the optical arrangement includes at least a first imaging optics 130 and a second optical relay arrangement 114. The first imaging optics 130 is configured for collecting optical radiation IR from a scene and generate an image of the scene on an image plane. The second optical relay arrangement 114 is positioned between the at least one polarization filter array 112 and the at least one detector array 122, and configured to relay radiation from the at least one polarization filter array 112 to the at least one detector array 122. More specifically, the optical relay arrangement 114 is configured to provide the at least one polarization filter array 112 and the at least one detector array 122 at conjugated optical planes, such that an image on the at least one polarization filter array 114 is reproduced on the at least one detector array 122. The at least one polarization filter array 112 is positioned at image plane with respect to radiation collected by the first imaging optics 130. More specifically, first imaging optics 130 operates to collect radiation from a scene and generate an image of the scene on the at least one polarization filter array 112. The polarization filter array 112 applies polarization encoding on the collected radiation, and the second optical relay arrangement 114 transmits the polarization encoded radiation to replicate the image plane on the detector array 122. This configuration enables collection of polarization information of the scene, while simplifying constructions where the polarization filter in not positioned directly on the detector array.

[0056] Camera system 100 may be configured as a complete system. Alternatively, in some embodiments, the present disclosure provides an optical module 110 adapted to be connected to a camera system. The optical module 110 includes the at least one polarization filter array 112 and the second optical relay arrangement 114. The optical module 110 may also include a casing having front and back connectors adapted to connect to an imaging optics 130, placing the at lease one polarization filter array 112 at an imaging plane of the imaging optics 130. The optical module 110 is further configured for connecting to an imaging system arrangement, e.g., camera casing 120, including at least one detector array 122. As indicated above, the second optical relay arrangement 114 is configured to relay radiation from the at lease one polarization filter array, onto a detector array 122 of the associated imaging / camera system, such that the at least one polarization filter array 112, and the detector array 114 are on conjugated image planes with respect to the imaging optics and a scene being imaged.

[0057] Reference is further made to Figs. 2A to 2C exemplifying three possible configurations of the polarization filter array 112 according to some embodiments of the present disclosure. Fig. 2A exemplifies a polarization filter array 112 having polarization filter call with two polarization orientations He and Vc; Fig. 2B exemplifies a polarization filter array 112 having polarization filter cells with four different orientations He, Vc, 45c and -45c; Fig. 2C exemplifies a polarization filter array having polarization filter cells of 6 different polarization orientations including 0°, 30°, 60°, 90°, -30°, and -60°. Fig. 2C also exemplifies radiation blocking cells Be within the array. Radiation blocking cells Be may be used in any type of polarization filter cell according to various embodiments of the present disclosure and may be used for calibration of the camera system 100 and / or optical relay module 110 according to some embodiments of the present disclosure. As indicated, the at least one polarization filter array 112 includes a plurality of polarization filter cells having a selected arrangement. To provide effective polarization data on a scene, the polarization filter array 112 and the optical relay arrangement 114 are both positioned and aligned, providing that radiation coming from the polarization filter cells is directed to a respective one or more detector elements (pixels of the detector array 122. Accordingly, the optical relay module 110, and / or the camera system 100, is configured to provide direct correspondence between polarization filter cells of the polarization filter array 112 and detector elements (or pixels) of the detector array 122. Such correspondence may be a 1 : 1 correspondence where radiation passing through a polarization filter cell is directed to impinge on a respective detector element. In some other embodiments the correspondence is such that radiation transmitted through each polarization filter cell impinges on a set of 2, 4, 6, 9, 12, 16 or any other selected number of detector elements. This configuration may be used to enhance efficiency of radiation collection. Generally, each detector element of the detector array 122 received optical radiation transmitted through one respective polarization filter array, thereby collecting optical radiation having a specific polarization orientation.

[0058] For example, as shown in Fig. 2A, the polarization filter array 112 may include polarization filter cells having two different polarization orientations. As shown in the figure, polarization filter cells He are configured to transmit optical radiation with horizontal polarization orientation, and polarization filter cells Vc are configured to transmit optical radiation having vertical polarization orientation. Generally, polarization filter array utilizing two different polarization orientations, may use any two orthogonal polarization orientations. The term vertical and horizontal as used here generally relate to vertical and horizontal polarization orientations with respect to any selected axis.

[0059] In some embodiments, e.g., as exemplified in Figs. 2B and 2C, the polarization filter array 112 may include polarization filter cells of two orthogonal orientations, and polarization filter cells having two or more additional polarization orientations. Fig. 2B exemplifies a polarization filter array including polarization filter cells having horizontal polarization orientation He, vertical polarization orientation Vc, as well as 45° orientated polarization filter cells and -45° oriented polarization filter cells. The polarization filter cells are generally arrangement in clusters or sub-array units, to provide substantially uniform distribution of polarization data across the frame of an image. The arrangement of polarization filter cells may be generally similar to arrangement of chromatic filters in a Bayer filter, enabling imaging of a scene where each pixel of the image data includes intensity and polarization data (in parallel to intensity in different wavelength ranges for color images).

[0060] Fig. 2C exemplifies an additional sub-array configuration of the polarization filter array 112. In this exemplary configuration, the polarization filter array 112 include subarrays having six different polarization orientations including 0°, 30°, 60°, 90°, -30°, and -60° polarization orientations. It should be noted that other selected arrangements of the polarization filter cells, or number of different polarization orientations may be used. The additional number over two orthogonal polarization orientations, enable improved polarization data on a scene. Such polarization data may for example enable identifying angular relation of various surfaces in an image, detection of different materials, etc.

[0061] Additionally, Fig. 2C illustrates several opaque filter cells Be. The opaque, or blocking, cell are configured to block transmission of optical radiation, resulting in dark pixels in the corresponding image data generated by the detector array. The sue of opaque cells Be is directed to allow spatial calibration of the polarization filter array 112 and optical relay arrangement 114 with respect to the detector array 122, such that optical radiation of different polarization filter cells is directed at different corresponding detector elements. It should be noted that opaque filter cells Be may be used in any of the above-described configurations of the polarization filter array and are not limited to the specific example of Fig. 2C. For example, opaque filter cells may be used in a polarization filter array having two orthogonal polarization orientations as exemplified in Fig. 2A and in polarization filter cells as exemplified in Fig. 2B.

[0062] The operation of a polarization filter is well known in the art. However, to enhance understanding, Fig. 3 summarizes the operation of polarization filters in general. While the optical radiation, or light, arrives from a scene may be unpolarized light, i.e., including light components having various different polarization orientations. The polarization filter transmits only light components having one selected polarization orientation, while light components of orthogonal polarization orientation are blocked by the polarization filter. For any intermediate polarization orientation, the transmission follows a relation of It~Iocos2(ff) where 0 is the angle between direction of polarization orientation of light component and direction of polarization transmitted by the polarization filter. As indicated above, the polarization filter array 112 include a plurality of polarization filter cells, having two or more different orientations, such that each detector element of the detector array 122 collected light components of one selected polarization orientation. Arrangement of the polarization filter cells in sub-arrays or clusters provides polarization information distributed across the image frame, providing polarization data on different locations in the scene.

[0063] Reference is now made to Fig. 4 exemplifying an optical arrangement of a camera system 100 according to some embodiments of the present disclosure. Fig. 4 also exemplifies light ray propagation through the camera system, illustrating the configuration placing the polarization filter array 112 and the detector array 122 at conjugated optical planes. As exemplified in Fig. 4, the camera system 100 includes a first imaging optics 130, generally including one or more lenses, apertures, etc. The first imaging optics 130 collects optical radiation from a scene to provide an image on an image plane, where the polarization filter array 112 is located. The optical radiation collected from the scene include various polarization orientations and is generally nonpolarized optical radiation.

[0064] The collected optical radiation impinges on the polarization filter array 112, and each of the different polarization filter cells transmits radiation components of the respective polarization orientation, while blocking radiation components of orthogonal polarization orientations. The optical radiation transmitted by the polarization filter array 112 is relayed using optical relay arrangement 114 onto the detector array 122. In this example optical relay arrangement 114 includes a first lens 114a, second lens 114b, third lens 114c, fourth lens 114d, and fifth lens 114e. the different lenses 114a-114e of the optical relay arrangement 114 provide for relaying an image from a first plane defined by location of the polarization filter array, onto a second plane defined by location of the detector array. Optical lenses 114a to 114e may be any type of optical lens. For example, lenses 114a to 114e may include spherical and / or aspherical lenses. In some embodiments lenses 114a to 114c are aspheric lenses.

[0065] The optical relay arrangement 114 is preferably configured to provide magnification M being within the range of 0.5 to 2, selected in accordance with relative dimensions of the polarization filter array 112 and the detector array 122. In some embodiments, the magnification of the optical relay arrangement 114 may be selected within the range between 0.8 and 1.5, in some embodiments the magnification of the optical relay arrangement 114 may be between 0.9 and 1.1, and in some embodiments the magnification is unity. Further, the optical relay arrangement 114 may be configured with numerical aperture NA between 0.7 and 0.9, and preferably with NA of about 0.9. The high numerical aperture may be selected to provide efficiency in relay of optical radiation between the polarization filter array and the detector array, and to avoid image degradation that may be associated with the relay operation. Generally, the magnification may be determined in accordance with relative size of unit cells of the polarization filter array 112 and detector elements of the detector array 122. Typically, a detector element may have a size in the range of 10-25 micrometer per detector element (pixel). To enable efficient imaging, the polarization filter cells of the polarization filter array 112 may also be within 10-25 micrometer size.

[0066] A larger illustration of the optical relay arrangement 114 is exemplified in Fig. 5, showing an example of optical configuration of a relay module 110 including a polarization filter array 112 and optical relay arrangement 114 according to some embodiments of the present disclosure. As shown, optical relay arrangement 114 includes a selected number of lenses, exemplified by lenses 114a to 114e, and may include additional optical elements such as aperture (pinhole) AP illustrated by lines extending from lens element 114b.

[0067] The optical relay arrangement 114 and the polarization filter array 112, forming together optical module 110 may be placed within a case, typically cylindrical, having first and second adaptors for connecting to a respective imaging lens arrangement 130 and to imaging system casing 120 as exemplified in Fig. 1. The adaptors may be any type of adapters, generally used in conventional optical systems.

[0068] Additionally, the optical module 110, including the optical relay arrangement 114, may preferably be configured to reduce thermal sensitivity of the module 110. Accordingly, the lenses and other optical elements of optical relay arrangement 114 are selected and configured to provide a-thermal response within a temperature range between 60°C and -40°C. In some embodiments, the optical relay module has maximal allowed thermal variation of focal lengths of the optical elements thereby of up to 0.6%.

[0069] Generally, the camera system 100, and / or the optical module 110 according to various embodiments of the present disclosure may be configured for operation is any selected wavelength range. In some embodiments, the camera system 100 and / or optical module 110 may be operable in infrared radiation. More specifically, while polarization detector arrays operable in visible spectrum may be relatively affordable, similar polarization detectors operable in infrared spectrum are typically very costly. The present disclosure thus enables reduction in costs providing at least one polarization filter array, relayed from a respective detector array, enabling the flexibility to operate the detector array for general imaging applications, as well as for polarization imaging applications in accordance with operators’ decision. Accordingly, in some embodiments, the camera system 100 and / or optical module 110 described above may be operable within wavelength range between 1 and 16 micrometers. In some embodiments the wavelength range may be between 2 and 6 and between 7 and 14 micrometers. In some embodiments, the wavelength range may be between 3 and 5 micrometers. In some further embodiments. The wavelength range may be between 8 and 12 micrometers.

[0070] A difficulty that may be associated with the use of optical relay arrangement 114 is exemplified in Fig. 6. Fig. 6 illustrates a distorted arrangement of sub-arrays 113 of the polarization filter array 112. In some embodiments, the use of optical relay arrangement 114 may result in certain distortions of the collected image when relayed between the polarization filter array 112 to the detector array 122. The distortion is associated with arrangement of the optical elements of optical relay arrangement 114 and can be compensated by arrangement of sub-arrays 113 (clusters) of the polarization filter array 112. As indicated above, polarization filter cells of the polarization filter array 112 are preferably arranged in clusters or sub-arrays, to ensure generally uniform distribution of polarization data across the frame of collected images. In some embodiments, where the optical relay arrangement 114 may cause image distortion above a selected threshold, this may be solved by proper arrangement of the polarization filter clusters 113, in accordance with the distortion. Fig. 6 exemplifies an arrangement of the polarization filter clusters 113 at varying distances between them, in an arrangement selected to compensate for distortions associated with the optical relay arrangement 114.

[0071] Generally, when arranged in a pattern selected to compensate for distortion of the optical relay arrangement 114, spaces between the clusters of polarization filter cells may be configured to block radiation transmission, to reduce noise and improve image quality.

[0072] Accordingly, the present disclosure provides a camera system, and an optical module, configured to enable polarization imaging. The camera system includes at least one polarization filter array positioned at a conjugated image plane with respect to detector array of the camera and utilizes an optical relay arrangement to relay optical radiation from the polarization filter array onto the detector array. The optical relay arrangement and arrangement and positioning of the polarization filter array provide that optical radiation collected by the different detector elements is polarized such that a typical detector element (or each detector element) collects optical radiation transmitted by a respective polarization filter cell of the polarization filter array.

[0073] It is to be noted that the various features described in the various embodiments can be combined according to all possible technical combinations.

[0074] 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 embodiments 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.

[0075] Those skilled in the art will readily appreciate that various modifications and changes can be applied to the embodiments 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) at least one detector array comprising a plurality of optical radiation sensitive pixels;(b) an optical arrangement configured for imaging a scene onto a plane defined by the at least one detector array;(c) at least one polarization filter array comprising a plurality of polarization filter cells, each polarization filter cell is associated with a corresponding pixel of the detector array; wherein the optical arrangement comprises at least a first imaging optics and a second optical relay arrangement, and the at least one polarization filter array is located at an image plane of the first imaging optics, and wherein the second optical relay is configured to relay radiation from the at least one polarization filter array to the at least one detector array.

2. The camera system of claim 1, wherein the at least one polarization filter array and the at least one detector array are positioned in conjugated optical planes.

3. The camera system of claim 1 or 2, wherein the at least one polarization filter array comprises a plurality of polarization filter cells, comprising polarization filter cells in at least two orthogonal orientations.

4. The camera system of claim 3, wherein the at least one polarization filter array comprises a plurality of polarization filter cells, comprising the polarization filter cells in at least two orthogonal orientations, and at least two intermediate polarization orientations.

5. The camera system of any one of claims 1 to 4, wherein the at least one polarization filter array comprises a plurality of polarization filter cells, comprising horizontal polarization filter cells, vertical polarization filter cells, 45° orientated polarization filter cells and -45° oriented polarization filter cells.

6. The camera system of any one of claims 1 to 5, wherein the at least one polarization filter array comprises an arrangement of sub-array units, and wherein each sub-array unit comprises an arrangement of a horizontal polarization filter cell, a vertical polarization filter cell, a 45° orientated polarization filter cell and a -45° oriented polarization filter cell.

7. The camera system of any one of claims 1 to 6, wherein the at least one polarization filter array comprises an arrangement of sub-array units, and wherein each sub-array unit comprises an arrangement of polarization filter cells having polarization orientation of ±30°, ±60°, 0°, and 90°.

8. The camera system of any one of claims 1 to 7, wherein filter cells of the at least one polarization filter array being arranged at varying distances between them in accordance with spatial optical distortion of the second optical relay arrangement.

9. The camera system of any one of claims 1 to 8, wherein the at least one polarization filter array comprises at least one opaque region thereby enabling alignment of the at least one polarization filter array with respect to pixel arrangement of the at least one detector array.

10. The camera system of any one of claims 1 to 9, wherein the second optical relay arrangement is characterized by magnification between 0.5 and 1.5.

11. The camera system of claim 9, wherein the second optical relay arrangement has magnification of m=l.

12. The camera system of claim 9 or 10, wherein the second optical relay arrangement is characterized by numerical aperture AN in a range between 0.7 and 0.9.

13. The camera system of any one of claims 1 to 12, configured for operating in infrared radiation spectrum.

14. The camera system of claim 13, configured for collecting optical radiation within a wavelength range between 7 and 14 micrometers.

15. The camera system of claim 13, configured for collecting optical radiation within a wavelength range between 3 and 5 micrometers.

16. The camera system of any one of claims 1 to 15, wherein the optical arrangement is configured for passive thermalization within a temperature range between -40°C and 60°C.

17. An optical module configured to be attached to an imaging system and comprising an optical relay arrangement and a polarization filter array; the optical relay arrangement comprises one or more optical elements and is configured to relay optical radiation transmitted through the polarization filter array onto a detector array of the imaging system; the polarization filter array comprises a plurality of polarization filter cells having at least two different polarization orientations; wherein the optical module is configured such that the polarization filter cells correspond to pixels of a detector array of thecorresponding imaging system such that each pixel collects radiation associated with a respective polarization filter cell.

18. The optical module of claim 17, further comprising a case having first and second connection adaptors, the first connection adaptor is configured for connecting the optical module to the respective imaging system and the second connection adapter is configured for connecting the optical module to an imaging lens arrangement.

19. The optical module of claim 17 or 18 configured for connecting to a lens arrangement to provide imaging of collected radiation onto the polarization filter array.

20. The optical module of any one of claims 17 to 19, wherein the polarization filter array is positioned in a conjugated optical plane with respect to the detector of the imaging system.

21. The optical module of any one of claims 17 to 20, wherein the polarization filter array comprises a plurality of polarization filter cells, comprising polarization filter cells in at least two orthogonal orientations.

22. The optical module of claim 21, wherein the polarization filter array comprises a plurality of polarization filter cells, comprising the polarization filter cells in at least two orthogonal orientations, and at least two intermediate polarization orientations.

23. The optical module of any one of claims 17 to 22, wherein the polarization filter array comprises a plurality of polarization filter cells, comprising horizontal polarization filter cells, vertical polarization filter cells, 45° orientated polarization filter cells and -45° oriented polarization filter cells.

24. The optical module of any one of claims 17 to 23, wherein the polarization filter array comprises an arrangement of sub -array units, and wherein each sub -array unit comprises an arrangement of a horizontal polarization filter cell, a vertical polarization filter cell, a 45° orientated polarization filter cell and a -45° oriented polarization filter cell.

25. The optical module of any one of claims 17 to 24, wherein the polarization filter array comprises an arrangement of sub -array units, and wherein each sub -array unit comprises an arrangement of polarization filter cells having polarization orientation of ±30°, ±60°, 0°, and 90°.

26. The optical module of any one of claims 17 to 25, wherein filter cells of the polarization filter array are arranged at varying distances between them in accordance with spatial optical distortion of the optical relay arrangement.

27. The optical module of any one of claims 17 to 26, wherein the polarization filter array comprises at least one opaque region thereby enabling alignment of the polarization filter array with respect to pixel arrangement of the at least one detector array.

28. The optical module of any one of claims 17 to 27, wherein the optical relay arrangement is characterized by magnification between 0.5 and 1.5.

29. The optical module of claim 28, wherein the optical relay arrangement has magnification of m=l.

30. The optical module of claim 28 or 29, wherein the optical relay arrangement is characterized by numerical aperture AN in a range between 0.7 and 0.9.

31. The optical module of any one of claims 17 to 30, configured for operating in infrared radiation spectrum.

32. The optical module of claim 31, configured for collecting optical radiation within a wavelength range between 7 and 14 micrometers.

33. The optical module of claim 31, configured for collecting optical radiation within a wavelength range between 3 and 5 micrometers.

34. The optical module of any one of claims 17 to 33, wherein the optical arrangement is configured for passive thermalization within a temperature range between -40°C and 60°C.

35. The optical module of any one of claims 17 to 20, wherein the polarization filter array comprises a plurality of polarization filter cells, comprising horizontal polarization filter cells, vertical polarization filter cells, 45° orientated polarization filter cells and -45° oriented polarization filter cells.

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