System and method for testing an optical plate

Abstract

The invention provides a system and a method for testing defects of an optical plate. The optical plate has first and second end surfaces and a pair of mutually parallel major outer surfaces that support propagation of light through the optical plate by internal reflection at the major outer surfaces. The light source generates light and is disposed proximate the optical plate such that light generated by the light source enters the optical plate proximate the first end surface and propagates through the optical plate toward the second end surface by internal reflection at the major outer surface. The detector arrangement has at least a first detector disposed in association with a first one of the major outer surfaces and detects light generated by the light source exiting the optical plate through the first one of the major outer surfaces due to scattering caused by a flaw of light propagating through the optical plate by internal reflection.

Description

[0001] Cross - reference to related applications

[0002] This application claims priority from U.S. Provisional Patent Application No. 63 / 460,329, filed on April 19, 2023, the entire disclosure of which is incorporated herein by reference. Technical Field

[0003] The present disclosure relates to test systems and methods, and particularly to systems and methods for testing for defects in an optical plate by detecting scattered light. Background Art

[0004] Optical devices for near - eye displays (NEDs), head - mounted displays (HMDs), and head - up displays (HUDs) require large apertures to cover the area where the observer's (user's) eyes are located (commonly referred to as the eye - motion box or EMB (Eye Motion Box)). To achieve a compact device, the image to be projected onto the observer's eyes is generated by a small optical image generator (projector) with a small optical aperture. The image from the image projector is transmitted to the eyes through an optical waveguide (also referred to as a light - transmissive substrate or a light - guiding optical element). The image light from the projector is injected into the optical waveguide, and the optical waveguide guides the image light through total internal reflection at the mutually parallel main outer surfaces of the optical waveguide and gradually couples out the image light (e.g., via a diffraction element or a partial reflector embedded in the optical waveguide), thereby expanding (multiplying) the image in at least one dimension to generate a large aperture. Even the smallest defect in the optical waveguide, particularly a defect at or near one or more of the parallel main outer surfaces of the optical waveguide, can disrupt the conditions for total internal reflection. Therefore, even the smallest defect in the optical waveguide is critical to providing a clear and distinct image to the observer. Conventional measurement tools and instruments lack the sensitivity required to identify even minute defects in the optical waveguide. Summary of the Invention

[0005] The present disclosure provides systems and methods for testing for defects in an optical plate by detecting scattered light.

[0006] In accordance with the teachings of embodiments of the present disclosure, a system for testing for defects in an optical plate is provided. The optical plate includes a plurality of surfaces, the plurality of surfaces including a first end surface and a second end surface and a pair of mutually parallel major outer surfaces, the pair of mutually parallel major outer surfaces being configured to support the propagation of light through the optical plate by internal reflection at the major outer surfaces. The system includes: a light source that generates light and is deployed proximate to the optical plate such that the light generated by the light source enters the optical plate near the first end surface and propagates through the optical plate toward the second end surface by internal reflection at the major outer surfaces; and a detector device that includes at least a first detector, the first detector being deployed in association with a first major outer surface of the major outer surfaces and being configured to detect light that is generated by the light source and that exits the optical plate through the first major outer surface of the major outer surfaces due to scattering of the light that propagates through the optical plate by internal reflection caused by a defect.

[0007] Optionally, the detector device further includes a second detector that is deployed in association with a second major outer surface of the major outer surfaces.

[0008] Optionally, the system further includes: an absorber device that includes at least one light-absorbing surface, the absorber frame device being configured to be deployed relative to the optical plate such that the at least one light-absorbing surface is associated with a corresponding surface of the surfaces of the optical plate.

[0009] Optionally, the plurality of surfaces further includes a first edge surface and a second edge surface, and the at least one light-absorbing surface includes a plurality of light-absorbing surfaces, the plurality of light-absorbing surfaces including: a first light-absorbing surface associated with a first major outer surface of the major outer surfaces, a second light-absorbing surface associated with a second major outer surface of the major outer surfaces, a third light-absorbing surface associated with the second end surface, a fourth light-absorbing surface associated with the first edge surface, and a fifth light-absorbing surface associated with the second edge surface.

[0010] Optionally, the optical plate includes: one or more optical coatings at one or more of the major outer surfaces.

[0011] Optionally, the optical plate includes: at least one optical component deployed inside the optical plate between the major outer surfaces.

[0012] Optionally, the at least one optical component includes a plurality of partially reflective surfaces that are obliquely inclined with respect to the major outer surfaces.

[0013] Optionally, the at least one optical component includes a partially reflective surface that is parallel to the major outer surfaces.

[0014] Optionally, the optical plate is formed as a plurality of stacks that make up the optical plate.

[0015] Optionally, the optical plate is part of a combined stack of optical plates.

[0016] Optionally, the system further includes: an integrating sphere, the integrating sphere including an input region associated with a light source and at least a first output region associated with a first detector.

[0017] Optionally, the first output region is associated with a second end surface of the optical plate.

[0018] Optionally, the first output region is associated with one of the main outer surfaces of the optical plate.

[0019] Optionally, the system further includes: at least one computer processor, the at least one computer processor being electrically associated with the detector device and configured to process a signal generated by the detector device in response to the first detector detecting light leaving the optical plate generated by the light source to obtain an integrity measurement result of the optical plate.

[0020] Optionally, the integrity measurement result is a count of the number of times the first detector detects light leaving the optical plate generated by the light source, and the at least one processor is further configured to perform a comparison of the count of the number of detections with one or more thresholds and output the availability status of the optical plate based on the comparison.

[0021] In accordance with the teachings of embodiments of the present disclosure, a system for testing for defects in an optical plate is also provided. The optical plate includes a plurality of surfaces, the plurality of surfaces including a first end surface and a second end surface and a pair of mutually parallel main outer surfaces, the pair of mutually parallel main outer surfaces being configured to support light to propagate through the optical plate by internal reflection at the main outer surfaces. The system includes: an integrating sphere, the integrating sphere including an input region and at least a first output region; a light source, the light source generating light and positioned outside the integrating sphere and adjacent to the input region; and a detector device, the detector device including a photodetector, the photodetector positioned outside the integrating sphere and adjacent to the first output region, and the integrating sphere, the light source, and the detector device being arranged such that: light generated by the light source passes through the input region and enters the optical plate near the first end surface, and propagates through the optical plate toward the second end surface by internal reflection at the main outer surfaces, and light reflected from the inner surface of the integrating sphere passes through the output region to reach the photodetector, and the light reflected from the inner surface is a portion of the light that propagates through the optical plate by internal reflection at the main outer surfaces, and this portion of the light leaves the optical plate through one of the main outer surfaces due to scattering caused by a defect.

[0022] Optionally, the first output region is associated with a second end surface of the optical plate.

[0023] Optionally, the first output region is associated with one of the main outer surfaces of the optical plate.

[0024] Optionally, the system further includes: an imaging system having at least one image sensor associated with a second output region of the integrating sphere to capture one or more images of an interior portion of the integrating sphere.

[0025] Optionally, the integrating sphere is formed by a pair of hemispherical portions that are spatially separated from each other to form an air gap therebetween for accommodating the optical plate.

[0026] Optionally, the air gap defines an input region and an output region.

[0027] In accordance with the teachings of embodiments of the present disclosure, a system for testing for defects in an optical plate is also provided. The optical plate includes a plurality of surfaces including a first end surface and a second end surface and a pair of mutually parallel major outer surfaces that support light to propagate through the optical plate by internal reflection at the major outer surfaces. The system includes: a light source deployed in association with a first major outer surface of the major outer surfaces and configured to generate light incident on the first major outer surface of the major outer surfaces such that the generated light encounters a defect in the optical plate and a portion of the generated light undergoes scattering caused by the defect and is thus coupled into the optical plate and propagates towards the first end surface or the second end surface by internal reflection at the major outer surfaces; and a detector deployed in association with the first end surface or the second end surface such that the detector detects light that propagates through the optical plate by internal reflection at the major outer surfaces.

[0028] In accordance with the teachings of embodiments of the present disclosure, a method for testing for defects in an optical plate is also provided. The optical plate includes a plurality of surfaces including a first end surface and a second end surface and a pair of mutually parallel major outer surfaces that support light to propagate through the optical plate by internal reflection at the major outer surfaces. The method includes: deploying the optical plate relative to a detector device having at least a first detector and a light source such that the first detector is associated with a first major outer surface of the major outer surfaces and light generated by the light source enters the optical plate near the first end surface and propagates through the optical plate towards the second end surface by internal reflection at the major outer surfaces; and detecting light generated by the light source that leaves the optical plate through one of the major outer surfaces due to scattering caused by a defect.

[0029] Optionally, the detector device further includes a second detector and the optical plate is deployed such that the second detector is associated with a second major outer surface of the major outer surfaces.

[0030] Optionally, the optical plate includes one or more optical coatings at one or more of the major outer surfaces.

[0031] Optionally, the optical plate includes: at least one optical component disposed inside the optical plate between the main outer surfaces.

[0032] Optionally, the at least one optical component includes a plurality of partially reflective surfaces obliquely inclined to the main outer surfaces.

[0033] Optionally, the at least one optical component includes a partially reflective surface parallel to the main outer surface.

[0034] Optionally, the optical plate is formed as a stack of a plurality of constituent optical plates.

[0035] Optionally, the optical plate is part of a combined stack of optical plates.

[0036] Optionally, the method further includes: deploying an absorber device including at least one light-absorbing surface such that the at least one light-absorbing surface is associated with a corresponding surface among the surfaces of the optical plate.

[0037] Optionally, the plurality of surfaces further includes a first edge surface and a second edge surface, and the at least one light-absorbing surface includes a plurality of light-absorbing surfaces, the plurality of light-absorbing surfaces including: a first light-absorbing surface associated with a first main outer surface among the main outer surfaces, a second light-absorbing surface associated with a second main outer surface among the main outer surfaces, a third light-absorbing surface associated with the second end surface, a fourth light-absorbing surface associated with the first edge surface, and a fifth light-absorbing surface associated with the second edge surface.

[0038] Optionally, deploying includes: positioning the optical plate in an integrating sphere having an input region and an output region such that the input region is associated with a light source and the output region is associated with a first detector.

[0039] Optionally, the method further includes: capturing one or more images of an interior portion of the integrating sphere by at least one image sensor.

[0040] Optionally, the integrating sphere is formed of a pair of hemispherical parts spatially separated from each other to form an air gap therebetween, and deploying includes positioning the optical plate in the air gap.

[0041] Optionally, the scattering is caused by at least one flaw at one or both of the main outer surfaces.

[0042] Optionally, the method further includes: cleaning or polishing the optical plate to at least partially remove the at least one flaw.

[0043] Optionally, the scattering is caused by at least one flaw including one or more of the following: surface-level flaws or bulk flaws.

[0044] Optionally, surface-level defects are selected from the group consisting of recesses, scratches, chips, dust, dirt, debris, one or more particles, non-uniformities, residues of adhesives, rough areas, and discontinuities of the optical coating at one or both of the major outer surfaces.

[0045] Optionally, bulk defects are selected from the group consisting of non-uniformities at one or more internal portions of the optical plate and air bubbles in one or more internal portions of the optical plate.

[0046] Unless otherwise defined herein, all technical and / or scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure pertains. Although methods and materials similar or equivalent to those described herein can be used in the practice or testing of embodiments of the present disclosure, exemplary methods and / or materials are described below. In case of conflict, the patent specification, including definitions, will control. Additionally, the materials, methods, and examples are illustrative only and are not necessarily intended to be limiting. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] Some embodiments of the present disclosure are described herein by way of example only with reference to the drawings. By specifically and in detail referring to the drawings, it is emphasized that the details shown are by way of example and for the purpose of illustrative discussion of embodiments of the present disclosure. In this regard, the description in conjunction with the drawings enables those skilled in the art to clearly understand how embodiments of the present disclosure can be practiced.

[0048] Now referring to the drawings, where like reference numerals indicate corresponding or similar components. In the drawings:

[0049] Figure 1A is a schematic side view of a system for testing an optical plate according to an embodiment of the present disclosure, Figure 1A showing a light source for emitting light into a clean optical plate under test and a detector associated with a first major outer surface of the clean optical plate, the detector for sensing the light emitted by the light source, and showing the light propagating through the clean optical plate by internal reflection;

[0050] Figure 1B is associated with Figure 1A a corresponding schematic top view;

[0051] Figure 2 is a schematic side view similar to Figure 1A but in Figure 2 which the optical plate under test has a defect, and showing a portion of the light propagating through the optical plate by internal reflection deflecting out of the optical plate from the first major outer surface of the optical plate towards the detector.

[0052] Figure 3 is Figure 2 a schematic side view of a section of an optical plate, Figure 3 showing the interaction of the propagating light with the defects that scatter the light, such that a portion of the scattered light is deflected out of the optical plate towards a detector;

[0053] Figure 4 is similar to Figure 2 but Figure 4 shows an additional detector that is deployed to sense a portion of the propagating light that is deflected out of the optical plate from a second major outer surface of the optical plate;

[0054] Figure 5A and Figure 5B are respectively a schematic side view and a top view of a system for testing an optical plate according to an embodiment of the present disclosure, the system having a light absorption frame surrounding the optical plate under test;

[0055] Figure 6 is similar to Figure 5A but Figure 6 also shows an integrating sphere for receiving the optical plate under test according to an embodiment of the present disclosure;

[0056] Figure 7 is similar to Figure 6 but Figure 7 also shows a pair of imaging sensors forming an imaging system according to an embodiment of the present disclosure, the pair of imaging sensors being configured to capture an image of an interior portion of the integrating sphere;

[0057] Figure 8 is similar to Figure 6 but in Figure 8 according to an embodiment of the present disclosure, the integrating sphere is formed by a pair of hemispherical portions that are spatially separated from each other to form an air gap in which the optical plate under test can be received;

[0058] Figure 9 is a schematic side view of a system for testing an optical plate, wherein the optical plate under test has defects, Figure 9 showing a light source for emitting light into the optical plate and a detector for sensing the light emitted by the light source associated with a first major outer surface of the optical plate, and showing a portion of the light emitted by the light source that is deflected into the optical plate to propagate through the optical plate by internal reflection;

[0059] Figure 10 isFigure 9 Schematic side view of a section of an optical plate, Figure 10 showing the interaction of light emitted by a light source with a flaw that scatters the light, such that a portion of the scattered light is deflected at an angle and propagates through the optical plate by total internal reflection;

[0060] Figure 11 is similar to Figure 1A but in Figure 11 , the optical plate under test is in the form of a light guiding optical element having a pair of mutually parallel main outer surfaces and a series of mutually parallel partially reflecting inner surfaces that are obliquely inclined with respect to the main outer surfaces;

[0061] Figure 12 is similar to Figure 1A but in Figure 12 , the optical plate under test is formed as a stack of optically clean plates, and also shows an integrating sphere that houses the optical plate under test; and

[0062] Figure 13 is similar to Figure 12 but in Figure 13 , at least one of the optically clean plates in the stack under test has at least one flaw such that a portion of the light that propagates through the stack by total internal reflection is deflected out of the stack and reflected from the inner surface of the integrating sphere. DETAILED DESCRIPTION

[0063] Certain embodiments of the present disclosure provide systems and methods for testing flaws in an optical plate by detecting scattered light.

[0064] The principles and operations of the systems and methods according to the present disclosure can be better understood with reference to the accompanying drawings of the specification.

[0065] Before detailing at least one embodiment of the present disclosure, it should be understood that the present disclosure is not necessarily limited in its application to the details of the construction and arrangement of the components and / or methods set forth in the following description and / or illustrated in the drawings and / or examples. The present disclosure is capable of other embodiments or of being practiced or carried out in various ways. First, throughout this document, references are made to directions such as up and down, left and right, etc. These directional references are merely exemplary for illustrating embodiments of the present disclosure. Additionally, it should be noted that the optical plates shown in the figures are not necessarily drawn to scale.

[0066] The systems and methods of the present disclosure can be used to test various types and sizes of optical materials, and are of particular value when used to test smaller-sized optical plates that are used to fabricate optical substrate devices for use in near-eye displays (NEDs), head-mounted displays (HMDs), and head-up displays (HUDs), or are themselves optical substrate devices.

[0067] Referring now to the drawings, Figure 1A and Figure 1B schematically shows a system, generally designated 10, for testing for defects in an optical plate 50 in accordance with the teachings of embodiments of the present disclosure. Generally speaking, system 10 includes an illumination device 14 having at least one light source 15 for generating (emitting) light and a detection device 20 having at least one detector (i.e., an “optical sensor” or “photoelectric detector”) 21 for detecting / sensing light generated (emitted) by the light source 15 (specifically, light emitted by the light source 15 that enters the optical plate 50 and then exits the optical plate 50). System 10 may also include a processing subsystem 26 having at least one computerized processor 28 coupled to a computerized storage medium 30 (such as a computer memory, etc.), the processing subsystem 26 being electrically associated with the detection device 20 for receiving signals from the detection device 20 and deriving integrity measurements of the optical plate 50 from the received signals.

[0068] The optical plate 50 is formed of a light-transmissive material (such as glass). Generally speaking, the optical plate 50 includes a plurality of outer surfaces, the plurality of outer surfaces including a pair of mutually parallel main outer surfaces 52, 54 that support the propagation of light through the optical plate 50 by internal reflection at the main outer surfaces 52, 54. In the non-limiting example shown in the figures, the outer surfaces also include a pair of opposite end surfaces 56, 58 and a pair of edge surfaces 60, 62.

[0069] Incidentally, the propagation of light through the optical plate 50 by internal reflection can be total internal reflection (TIR), whereby light propagating at an angle greater than the critical angle (partially defined by the refractive index of the light-transmissive material and the refractive index of the medium (such as air, optical coating, etc.) surrounding the optical plate 50) incident on the main outer surfaces 52, 54 is totally internally reflected at the main outer surfaces 52, 54. Alternatively, the propagation by internal reflection can be achieved by an optical coating (such as an angle-selective reflection coating) applied to the main outer surfaces 52, 54 to effect the reflection of light incident on the main outer surfaces 52, 54 within a specific angular range. In the context of this document, light propagating through a light-transmissive material (such as an optical plate) by internal reflection is referred to as being “guided” or “trapped” by internal reflection.

[0070] Returning to Figure 1Aand Figure 1B , the lighting device 14 and the detector device 20 are each deployed near the optical plate 50 in a specific arrangement and orientation. Specifically, the optical plate 50 and the detector device 20 are arranged relative to each other such that the detector 21 is associated with one of the main outer surfaces 52 (the upper surface 52 in this example, but the detector 21 can also be deployed in association with the lower surface 54) to be able to detect the light leaving (escaping) the optical plate 50 from one of the main outer surfaces 52. A collection optical device (not shown) can be deployed between the detector 21 and the main outer surface of the optical plate 50 to direct the escaping light onto the detector 21. The optical plate 50 and the lighting device 14 are arranged relative to each other such that the light generated by the light source 15 (schematically represented in Figure 1A as an illumination beam having a sample ray 16) enters the optical plate 50 near one of the end surfaces 56 (e.g., through the end surface 56), and propagates through the optical plate 50 along a propagation direction toward the other end surface 58 by internal reflection at the main outer surfaces 52, 54. This deployment can be achieved by positioning the light source 15 close to the end surface 56. The light propagating through the optical plate 50 by internal reflection is labeled 17 in the figure. In the example shown, the propagation direction is aligned with the elongation direction of the optical plate 50 (horizontal direction in the figure). When the light 17 reaches the end surface 58, in some cases, the light can freely leave the optical plate 50 through the surface 58, or in other cases, it can be absorbed by a light-absorbing coating deployed at the end surface 58.

[0071] The deployment of the lighting device 14 and the detector device 20 relative to the optical plate 50 can be facilitated by the mounting device 12, which receives the optical plate 50 and positions it. The mounting device 12 can be configured to receive the optical plate 50 and position the received optical plate 50 in a specific arrangement and orientation relative to the light source 15 and the detector device 20. Preferably, the light source 15 and the detector 21 are positioned relative to the mounting device 12 in a specific position and orientation such that when the optical plate 50 is received into the mounting device 12, a specific arrangement and orientation of the optical plate 50 relative to the light source 15 and the detector device 20 are provided. In certain embodiments, the lighting device 14 and the detector device 20 are mechanically coupled to the mounting device 12 in a specific position and orientation relative to the mounting device 12. In other embodiments, the mounting device 12 is mechanically separated from the lighting device 14 and the detector device 20. The mounting device 12 (although only schematically shown in the figure) can be implemented as any suitable mechanical device commonly used to hold an optical substrate (such as a substrate holder used in spectroscopy or a bench-top optical holder).

[0072] Regarding the lighting device 14, it should be noted that the wavelength of the light emitted by the lighting device 14 can be in any suitable region of the electromagnetic spectrum, such as the visible spectrum, infrared, UV, etc. In embodiments where more than one light source 15 is used, the light sources 15 can emit light of the same wavelength or different wavelengths. It should also be noted that the light source 15 can generate a wide beam that fills the input aperture of the optical plate 50. In this regard, the ray 16 of the illumination beam emitted by the Figure 1A light source 15 shown in is only one of the numerous rays across the beam. Therefore, the propagated light 17 shown in the figure is only a sample of the propagated illumination beam, which corresponds to one of the sample rays of the input illumination, and the propagated light 17 actually preferably fills the optical plate 50 such that all parts (or practically all parts) of the main outer surface are illuminated by the illumination 17. Alternatively, the light source 15 can generate a narrower beam, and a mechanism for translating and tilting the light source 15 can be provided to accommodate the mechanical span of the input aperture.

[0073] When the optical plate 50 is ideal, the optical plate 50 does not include any defects, or only includes minor or slight defects, and the conditions for total internal reflection are maintained along the entire propagation direction of the optical plate 50, such that the propagated light 17 is guided through the optical plate 50 without leakage through the main outer surfaces 52, 54, or without significant intensity loss. Under such ideal conditions, the optical plate is referred to as a "clean plate". In Figure 1A , the optical plate 50 is a clean plate. Therefore, the light 17 is guided through the optical plate 50 by total internal reflection without leakage, and the detector 21 does not detect any light (or a negligible amount of light) leaving through the main outer surface 52 associated with the detector 21.

[0074] Now turning to Figure 2 , here the optical plate 50 is no longer a "clean plate", but includes one or more defects (which can also be interchangeably referred to herein as "surface and / or bulk defects of the optical plate", "surface or and / or bulk non-uniformities of the optical plate", or "surface and / or bulk anomalies of the optical plate"), which disrupt the conditions for total internal reflection and can present as "haze" in the optical plate 50. Specifically, these defects (which can be surface and / or bulk defects) cause a portion of the propagated beam 17 to become scattered when the propagated beam 17 encounters the defect (represented as a dot 51 in the figure), i.e., a portion of the beam experiences scattering caused by the defect, resulting in the propagation of light at an angle that does not satisfy the conditions for total internal reflection, which ultimately causes a portion of the propagated beam 17 to leave (escape) the optical plate 50 through one or more of the main outer surfaces 52, 54. In Figure 2In [the figure], light propagating at an angle that does not satisfy the total internal reflection condition is represented as a dashed ray, while light that exits the optical plate 50 through the main outer surface 52 (due to scattering) is represented by ray 19 (which is a continuation of the dashed ray). In the example shown, ray 19 exits the optical plate 50 at point 63 on the main outer surface 52. In this case, the detector 21 deployed in association with the main outer surface 52 through which the light escapes detects / senses the escaping light 19.

[0075] Figure 3 is Figure 2 a close-up of a section of the optical plate 50, Figure 3 showing an example of a flaw 51 in the optical plate 50 that may cause the propagating beam 17 to scatter. Here, the flaw 51 is a dent in the main outer surface 54, generally formed as a recess, depression, pit, cavity, or slit in the main outer surface. This dent causes a small portion of the main outer surface 54 to project inward into the inner part of the optical plate 50. The projecting portion (i.e., the protrusion) is generally labeled 53 in Figure 3 [the figure]. Due to the presence of the dent, the portion of the light 17 that encounters the protrusion 53 is reflected (i.e., scattered) in multiple directions by the protrusion 53, schematically represented by the scattered rays 18. Due to the variation in the surface profile of the protrusion 53, the scattered rays 18 are scattered in different directions such that at least some of the scattered light 18 propagates at an angle that does not satisfy the total internal reflection condition and escapes from the optical plate 50 (e.g., as ray 19 through point 63). Some of the scattered light can be at an angle that satisfies the total internal reflection condition, so a portion of the intensity of some of the scattered light can continue to propagate through total internal reflection at the main outer surfaces 52, 54.

[0076] It should be noted that, Figure 3The indentations shown are merely illustrative examples of the types of defects that may be present in the optical plate under test, and are illustrative examples of the locations of defects in the optical plate under test. In general, defects in the optical plate under test that can be detected by embodiments of the present disclosure can be located in different regions of the optical plate, including the outer portion of the optical plate (i.e., portions of one or both of the main outer surfaces 52, 54) and / or the inner portion of the optical plate (i.e., the bulk portion), although in some cases, the defects are more often located near the main outer surface (i.e., the outer and / or inner portions of the optical plate, but near the main outer surface). In addition, embodiments of the present disclosure can detect (i.e., identify) the presence of various types of surface defects and bulk defects, including but not limited to: recesses, scratches, chips, dust, dirt, debris, particles, non-uniformities, or residues of adhesives located on one or both of the main outer surfaces 52, 54; discontinuities or non-uniformities of the optical coating applied on one or both of the main outer surfaces 52, 54 (including cracking, peeling, flaking, blistering, and clouding in the optical coating); rough regions on one or both of the main outer surfaces 52, 54; non-uniformities (i.e., bulk non-uniformities) in one or more inner portions or regions of the optical plate; gas (such as air) bubbles in one or more inner portions or regions of the optical plate, etc. Defects in the optical plate under test may occur for various reasons. For example, a rough region on the main outer surface may be caused by the optical plate being incompletely polished or partially polished. For example, polishing may also, for example, produce recesses. For example, scratches or chips may appear on one or both of the main outer surfaces due to improper handling of the optical plate (such as dropping). Residues of adhesives may accumulate on one or both of the main outer surfaces of the optical plate, for example, in the case where the optical plate is formed of multiple material layers that are glued (adhesively bonded) to each other. For example, dust, dirt, debris, and particles may naturally accumulate on one or both of the main outer surfaces over time or during the manufacturing process, and may be removable by cleaning or polishing. For example, bulk defects such as bubbles and internal non-uniformities may occur during the manufacturing process of the raw materials used to produce the optical plate, for example, during the formation of the glass from which the optical plate is extracted.

[0077] It should also be noted that Figure 3 the scattering pattern shown is merely a representation of the possible scattering patterns caused by defects in the optical plate. In principle, Figure 3 some of the light in Figure 2 and Figure 3It is shown that the escaping light 19 exits the optical plate 50 through the upper major outer surface 52 at a specific point 63, but the light that escapes the optical plate 50 due to the lack of internal reflection conditions caused by scattering due to defects may exit the optical plate 50 at different points along either major outer surface, where it may be sensed by the detector 21 (or detectors).

[0078] In response to detecting / sensing the light 19 escaping from the optical plate 50, the detector 21 generates a detector signal. In some embodiments, the detector device 20 provides these signals to the processing subsystem 26, and the processor 28 may derive an integrity measurement of the optical plate 50 from the received detector signals. In some embodiments, the processing subsystem 26 may use the integrity measurement to detect / identify the presence of one or more defects on the optical plate. In one example embodiment, the integrity measurement is in the form of a signal count, and the processing subsystem 26 counts the number of detections (by the detector 21) of the light 19 that exits the optical plate 50 (generated by the light source 15). In some embodiments, if the counted number of detections is above a threshold, the processing subsystem 26 may indicate a positive detection / identification of one or more defects. In some embodiments, the processing subsystem 26 may compare the counted number of detections with one or more thresholds and output the availability status or classification (or integrity characterization) of the optical plate 50 based on the comparison. For example, if the signal count is within a first range, e.g., in the range of 0 to 50, the processing subsystem 26 may characterize the optical plate 50 as a "clean plate". For example, if the signal count is within a second range, e.g., in the range of 50 to 200, the processing subsystem 26 may characterize the optical plate 50 as a "dirty plate". Depending on the location and / or type of the defect, the "dirty plate" may be cleaned or polished to remove the defect and then optionally retested. An imaging system may be used to identify the location of the defect, as discussed in subsequent sections of the present disclosure. As another example, if the signal count is within a third range, e.g., above 200, the processing subsystem 26 may characterize the optical plate 50 as a "non - usable plate" (i.e., a plate that cannot be sufficiently cleaned or polished to reduce the signal count to the first range), and the optical plate may be discarded or recycled. Obviously, any appropriate number of threshold comparisons and corresponding categories may be applied.

[0079] Now referring to Figure 4 , Figure 4 is shown in connection with Figures 1A to 2An embodiment of a similar system 10 is shown, but in this embodiment, the detector device 20 includes a second detector 21b deployed in association with the lower major outer surface 54 of the optical plate 50. This configuration allows the detector device 20 to detect light emitted from both major outer surfaces of the optical plate 50, effectively doubling the test area that can be inspected by the detector device 20, thereby increasing the overall signal-to-noise ratio (SNR) of the detector signal. In the example shown, two defects 51 scatter the light 17 propagating by internal reflection, causing the light to propagate at an angle that does not satisfy the internal reflection condition (represented as dashed light rays in the figure), which results in the light 19 escaping through both major outer surfaces 52, 54.

[0080] The signal strength of the detector signal can be further increased by employing a light absorption device or frame at some or all of the outer surfaces of the optical plate 50 to reduce the effect of stray light that is not caused by scattering. Figure 5A and Figure 5B A non-limiting example of such an embodiment is schematically shown, in which the absorber device 32 (in the form of an absorber frame) includes a plurality of light absorption surfaces 34, 36, 38, 40, 42 associated with the outer surfaces 52, 54, 58, 60, 62 respectively. In one non-limiting implementation, the light absorption surfaces 34, 36, 38, 40, 42 are implemented as black paint coatings applied to a base surface placed in association with the above-mentioned surfaces of the optical plate 50. In embodiments where light propagates through the optical plate by total internal reflection, a small air gap is preferably present between the light absorption surfaces 34, 36 and the corresponding major outer surfaces 52, 54 such that the conditions for total internal reflection are maintained.

[0081] Although Figure 5A and Figure 5B the illustrated embodiment shows each of the outer surfaces 52, 54, 58, 60, 62 having an associated light absorption surface, reasonable performance can still be achieved in cases where only some of the outer surfaces have an associated light absorption. For example, in certain embodiments, only the edge surfaces 60, 62 may have associated light absorption surfaces 40, 42. It should also be noted that embodiments using an absorber device can be combined with embodiments deploying a single detector (such as Figures 1A to 2 the embodiment shown in

[0082] The SNR of the detector signal can be further increased by employing an integrating sphere, which may be particularly advantageous in cases where the optical plate includes significant surface or bulk scattering centers. Figure 6An exemplary embodiment is schematically shown in which the optical plate 50 is housed in an integrating sphere 70, which is a hollow spherical cavity 73 known in the art having an inner surface 71 coated with a diffusive white reflective coating. The integrating sphere 70 includes an input region 72 and at least one output region 74. The input and output regions may be defined as openings or ports in the sphere 70, or alternatively may be light transmissive regions, such as light transmissive windows. In the embodiment shown, the light source 15 is disposed outside the integrating sphere 70 and adjacent to the input region 72 of the integrating sphere 70 such that the light 16 emitted by the light source 15 passes through the input region 72 and into the optical plate (e.g., near the end surface 56), and propagates through the optical plate 50 by internal reflection at the main outer surfaces 52, 54 towards the other end surface 58. Similar to the previously described embodiments, when the propagating light beam 17 encounters a flaw, a portion of the propagating light beam 17 undergoes scattering such that a portion of the propagating light beam 17 exits the optical plate 50 through the main outer surfaces 52, 54. The light 19 that exits the optical plate 50 due to scattering caused by the flaw is incident on the inner surface 71 of the integrating sphere 70. The incident light 19 is reflected from the inner surface 71 as light 19b. This reflected light 19b passes through the output region 74 of the integrating sphere 70 and reaches the detector 21, which is disposed outside the integrating sphere 70 and adjacent to the output region 74.

[0083] Although the output region 74 and thus the detector 21 are shown as being located adjacent to the end surface 58 of the optical plate 50, the position of the output region and the detector can be arbitrary, mainly due to the fact that the exiting light 19 is typically subject to uniform scattering or the diffusion effect of the integrating sphere, causing the light 19 to undergo multiple reflections from the inner surface 71 of the integrating sphere 70 and thus resulting in deflection and multiple angles of the exiting light 19.

[0084] Now refer to Figure 7 , Figure 7 With Figure 6The implementation is similar, but it includes an imaging system (which can be functionally part of the detector device or separated from the detector device), and the imaging system has at least one image sensor, and the at least one image sensor is shown as a pair of image sensors 22, 24 in this example. The image sensors 22, 24 (which can be implemented as cameras) are each deployed outside the integrating sphere 70 and close to the corresponding output regions 76, 78. The image sensors 22, 24 are angled with respect to the corresponding output regions 76, 78 such that a portion of the inner cavity 73 is within the respective fields of view of the image sensors 22, 24, so that the image sensors 22, 24 can view the inner cavity 73 through the output regions 76, 78 and capture one or more images of an inner portion of the integrating sphere 70, in particular one or more images of one or more regions of the optical plate 50 within the integrating sphere 70. A processing subsystem 26 that is electrically associated with the image sensors 22, 24 of the imaging system can use these images to further characterize the physical location / position of defects in the optical plate 50. For example, the processing subsystem 26 can correlate the detector counts with the images captured by the imaging system to determine the location of the defects that cause scattering and result in an increase in the detector signal counts of the detector 21.

[0085] It is obvious that the number of image sensors and the deployment positions of the image sensors are not limited to any specific number or deployment configuration. In fact, any suitable number of image sensors (including a single image sensor) and any suitable deployment configuration can be used, but it is advantageous to use a sufficient number of image sensors with a specific deployment configuration such that the combined fields of view of the image sensors cover the entire surface area of the main outer surfaces 52, 54 of the optical plate 50.

[0086] It should be noted that although the absorber arrangement 32 is shown in the Figure 6 and Figure 7 illustrated implementation, the integrating sphere implementation can still be advantageously used in cases without the absorber frame 32.

[0087] Although the integrating sphere implementations described so far involve an integrating sphere that is implemented as a single-piece hollow spherical cavity, other implementations in which the integrating sphere is formed by two separate hemispherical parts are also possible. Figure 8 An example of such an implementation is shown, in which the integrating sphere 70 is formed by a pair of hemispherical parts 80, 82 that are spatially separated from each other to form an air gap 84 therebetween, and the air gap 84 is large enough to be able to accommodate the optical plate 50 therein. In this implementation, the air gap 84 defines the input region 72 and the output region 74.

[0088] Figure 8The illustrated embodiment has particular value when used for mass production and testing of an optical plate or an optical product made from an optical plate. Specifically, the size of the air gap 84 allows for quick accommodation and replacement of the optical plate therein, enabling sequential analysis of a large number of optical plates in a rapid manner.

[0089] Figure 8 The embodiment of Figure 7 shown can be used for further advantages when combined with an imaging system such as

[0090] The embodiments described so far relate to a detector deployed to detect / sense light escaping from the main outer surface of the optical plate. However, advantageously, a detector is employed to detect / sense the propagating light 17 naturally leaving the optical plate 50. In one configuration, namely Figures 1A to 2 a variant of the illustrated embodiment, the detector 21 can be deployed in association with the end surface 58 through which the propagating light 17 naturally leaves the optical plate 50. In such an embodiment, the detector 21 can be configured to monitor the intensity of the propagating light 17 naturally leaving the optical plate 50 through the end surface 58, and the processing subsystem 26 can derive an integrity measurement based on the monitored intensity. For example, the processing subsystem 26 can determine a baseline (i.e., "nominal") intensity for a "clean plate", then compare the monitored intensity of the optical plate under test with the baseline intensity, and output a characterization of the optical plate under test based on the comparison. As another example, when the light source 15 is translated and tilted to cover a range of illumination angles, the intensity can be monitored to identify changes (such as drops) in the intensity. For example, if the light source 15 is angled in a first direction such that the light beam 16 does not encounter any defects, the output intensity monitored by the detector 21 will be maximum; if the light source 15 is then angled in a second direction such that the light beam 16 encounters a defect (or defects), the output intensity monitored by the detector 21 will be lower than the maximum intensity, and the processing subsystem 26 can characterize the optical plate 50 as a "dirty plate".

[0091] However, it should be noted that monitoring for intensity drops requires very high-precision detection and processing, mainly due to the fact that the leaks causing the intensity drops are usually too small to be accurately detected using conventional electronics. Thus, referring to Figures 1A to 8The described embodiments are generally more effective and perform better than the alternative embodiments mentioned above. Figure 9 An alternative embodiment that may be more effective is schematically shown in Figures 1A to 2 and is similar to the embodiment shown in Figure 9 except that the positions / orientations of the light source 15 and the detector 21 are swapped. Specifically, in the embodiment shown, the light source 15 is deployed in association with one of the main outer surfaces 52, and the detector 21 is deployed in association with one of the end surfaces 56. Here, the light source 15 emits a light beam 16, which is incident on the main outer surface 52. If any of the light beam 16 encounters a flaw, a portion of the light beam 16 becomes scattered in multiple directions by the flaw (i.e., undergoes flaw-induced scattering) and is deflected into the optical plate 50. At least some of the light is deflected at an angle that satisfies the conditions for total internal reflection ( Figure 9 One such deflected ray is represented as a dashed ray in

[0092] Figure 10 ), so at least some of the scattered light is coupled into the optical plate 50 and propagates towards the end surface 56 by total internal reflection at the main outer surfaces 52, 54. When reaching the end surface 56, the propagating light 17 naturally / freely exits the optical plate 50 and is detected / sensed by the detector 21.

[0092] Figure 10 is Figure 9 a close-up of a section of the optical plate 50 of Figure 10 showing an example of a flaw 51 (with a protrusion 53) in the optical plate 50 that may cause scattering of the light 16, which results in a portion of the light 16 being coupled into the optical plate 50 by total internal reflection. As shown, the portion of the light 16 that encounters the protrusion 53 is reflected (i.e., scattered) in multiple directions by the protrusion 53, schematically represented by the scattered rays 18. The rays 18 are scattered in different directions due to the change in the surface profile of the protrusion 53, such that at least some of the scattered light 18 propagates at an angle that satisfies the conditions for total internal reflection and is coupled into the optical plate 50 (i.e., is guided / trapped within the optical plate 50 by total internal reflection), and thus propagates towards the end surface 56 by total internal reflection at the main outer surfaces 52, 54.

[0093] It should be clear that the detector 21 can be deployed in association with the other end surface 58 instead of the end surface 56. Alternatively, a pair of detectors can be deployed, each associated with a respective one of the end surfaces 56, 58. It should also be clear that either or both of the main outer surfaces 52, 54 can have a light source 15 deployed in association therewith, and one or more detectors 21 are correspondingly positioned.

[0094] In Figure 9 and Figure 10In the illustrated embodiment, the light source 15 may be configured to emit diffused light covering a wide angle such that the incident light beam 16 interacts with a large area of the main outer surface 52. In certain embodiments, in order to generate a wide beam, a scanning device such as a scanning mirror may be deployed adjacent to the light source 15. The light source 15 may be mounted to a mechanical sliding device (e.g., a motorized bracket) such that the light source 15 is capable of laterally moving along the elongation direction of the optical plate 50. However, it should be noted that light 16 from the light source 15 that is incident on the main outer surface 52 at a certain incident angle and does not interact with any defects may be coupled into the optical plate 50 and be trapped by total internal reflection due to the incident angle of the incident light. Therefore, care should be taken to ensure that the light 16 emitted by the light source 15 does not impinge on the main outer surface 52 at these incident angles such that only the light that interacts with defects will be trapped within the optical plate by total internal reflection.

[0095] The embodiments described above with reference to Figure 9 and Figure 10 may be combined with other embodiments (e.g., the embodiments described with reference to Figure 2 ). For example, an embodiment is contemplated in which a first light source may be deployed in association with the first end surface 56 or the second end surface 58, a first detector may be deployed in association with the upper main outer surface 52 or the lower main outer surface 54 to sense light emitted by the first light source that avoids total internal reflection due to one or more defects, and a second light source may be deployed in association with the lower main outer surface 54 or the upper main outer surface 52 to illuminate the optical plate, and a second detector may be deployed in association with the second end surface 58 or the first end surface 56 to sense light emitted by the second light source and deflected into the optical plate by one or more defects and thus trapped within the optical plate by total internal reflection. In such an embodiment, the pair of light sources may be operated asynchronously such that the pair of light sources alternate between light emission states (i.e., only one of the two light sources emits illumination at a given time). In such a configuration, if a light absorption frame is used, it is advantageous to employ a movable member that moves the light absorption surface associated with the main outer surface associated with the second light source away from the main outer surface when the second light source emits light. Alternatively, the pair of light sources may emit light simultaneously.

[0096] Optical plates that can be tested using the systems and methods according to embodiments of the present disclosure can take various forms. In one example, the optical plate is a sample of an optical material that has been pre-treated (e.g., cleaned, cut, polished, etc.) and is ready to be used as a raw material for constructing an optical substrate device (e.g., a Light-Guide Optical Element (LOE) available from Lumus Ltd. of Israel) for use in a near-eye display (NED), a head-mounted display (HMD), or a head-up display (HUD). In certain embodiments, the pre-treatment can include applying one or more layers of optical coatings to the main outer surface of the optical plate such that the main outer surface of the optical plate includes the optical coating. Non-limiting examples of the optical coating are angle-selective reflection coatings that can provide internal reflection conditions.

[0097] In other embodiments, the optical plate can include one or more embedded optical elements. For example, in certain embodiments, the optical plate can include a partially reflective surface or a polarization element that is embedded within the optical plate, parallel to the main outer surface of the optical plate, and extends partially along the elongation direction of the optical plate. In other embodiments, the optical plate itself is such an LOE that has a series of mutually parallel partially reflective inner surfaces embedded therein, and these mutually parallel partially reflective inner surfaces are obliquely inclined with respect to the main outer surface of the LOE, or obliquely inclined with respect to the elongation direction of the LOE, and they pass partially through the optical plate along the elongation direction. In such embodiments, the systems and methods according to embodiments of the present disclosure can be used to identify flaws or other defects in the LOE. Figure 11 An example of a system 10 for testing an optical plate implemented as an LOE is shown. Here, the LOE includes a series of mutually parallel partially reflective inner surfaces 66 that pass through the LOE along the elongation direction and are obliquely inclined with respect to the main outer surfaces 52, 54. It should be apparent that the position of the light source 15 and the orientation of the partially reflective surface 66 should inform the decision of where to deploy the detector 21. For example, in the configuration shown, light 16 is injected from the left end surface 56 and is coupled with a particular orientation of the partially reflective surface 66, causing a portion of the light 17 that propagates through the LOE by internal reflection to be deflected out of the LOE towards the lower main outer surface 54. Thus, in such a test configuration, the detector 21 should be deployed in association with the upper main outer surface 52. If the light source 15 were to be positioned near the right end surface 58 and the partially reflective surfaces 66 were to maintain their same orientation, then a portion of the light 17 that propagates through the LOE by internal reflection would be deflected out of the LOE towards the upper main outer surface 52, and thus the detector 21 would need to be deployed in association with the lower main outer surface 54.

[0098] In additional embodiments, the optical plate under test can be formed as a stack of constituent optical plates, where each plate in the stack can be configured as the optical plate 50. The constituent optical plates can be aligned and bonded together (e.g., using an optical adhesive applied at the major outer surfaces of some or all of the constituent optical plates in the stack). In these embodiments, the major outer surfaces of the constituent optical plates form the major inner surfaces of the stack of bonded plates, except for the upper major outer surface of the top optical plate in the stack and the lower major outer surface of the bottom optical plate in the stack (which form the upper and lower major outer surfaces of the stack, respectively).

[0099] The optical adhesive used to bond the constituent optical plates together can be or can not be a refractive-index-matching adhesive. In the case where the optical adhesive is refractive-index-matching, the stack of optical plates will behave as a thick optical plate with an internally embedded optical coating, where light can propagate by internal reflection between the major outer surfaces of the stack. In the case where the optical adhesive is not refractive-index-matching and the refractive index of the optical adhesive is sufficiently lower than the refractive index of the optical plate material to define a critical angle, each optical plate in the stack will behave like an optical plate in air, i.e., for each optical plate, light incident on the major outer surface of the optical plate at an angle greater than the critical angle will be trapped between the major outer surfaces by total internal reflection. In this case, flaws in the stack of optical plates may cause scattering, which results in the loss of the total internal reflection condition in the optical plate, thereby causing light to leave the optical plate and transmit through adjacent optical plates in the stack until it completely exits the stack. In embodiments testing such a stack of optical plates, it may be advantageous to employ an illumination device having a plurality of light sources. For example, the illumination device can include a light source for each optical plate in the stack of optical plates, where each light source provides input illumination to the corresponding optical plate of the stack of optical plates. Alternatively, a plurality of light sources can be provided, where each light source provides input illumination to a different respective group of the stack of optical plates. In practice, the stack can be formed of any number of two or more optical plates, provided that the geometry of the illumination device is adjusted accordingly.

[0100] It should be apparent that any of the previously described embodiments can be used to test such a stack of constituent optical plates. By way of a non-limiting illustrative example, Figure 12 an optical plate 50' formed from a stack of clean constituent optical plates 50 (the clean constituent optical plates 50 being bonded together with a refractive-index-matching optical adhesive) is shown, and it is deployed in association with Figure 6In a test apparatus similar to the apparatus shown (but without the absorption frame 32). Here, the optical plate 50' behaves like a thicker version of the optical plate 50. Accordingly, light 17 propagates through the optical plate 50' by internal reflection between the main outer surfaces 52, 54 of the optical plate 50' / stack, and no internally reflected light 17 escapes through the main outer surfaces 52, 54 (no scattering due to no defects). Figure 13 The following opposite example is shown: At least one of the constituent optical plates 50 in the stack has at least one defect such that the optical plate 50' itself has at least one defect. Here, at least part of the internally reflected light 17 escapes through one or more of the main outer surfaces 52, 54 as light 19.

[0101] As described above, the systems and methods of the present disclosure are applicable to testing optical plates of various sizes and are of particular value when used to test smaller-sized optical plate devices for manufacturing near-eye displays (NEDs), head-mounted displays (HMDs), or head-up displays (HUDs) in a small form factor or optical plate devices themselves. Nevertheless, the systems and methods of the present disclosure can still be used to test samples of any optical material that is a light-transmitting material having a pair of parallel main outer surfaces that can support light to propagate through it by internal reflection, including large-scale optical plates such as automotive windshields and portions of flat glass used as part of windows and / or doors.

[0102] The description of the various embodiments of the present disclosure has been presented for purposes of illustration, but the description is not intended to be exhaustive or limited to the disclosed embodiments. Many modifications and variations will be apparent to a person of ordinary skill in the art without departing from the scope and spirit of the described embodiments. The terms used herein are chosen to best explain the principles of the embodiments, the practical application, or the technical improvement of technologies found in the marketplace, or to enable other persons of ordinary skill in the art to understand the embodiments disclosed herein.

[0103] As used herein, unless the context clearly dictates otherwise, the singular forms "a", "an", and "the" include plural referents.

[0104] The word "exemplary" is used herein to mean "serving as an example, instance, or illustration". Any embodiment described as "exemplary" is not necessarily to be construed as preferred or advantageous over other embodiments and / or excludes features from other embodiments.

[0105] It should be understood that certain features of the present disclosure that are described in the context of separate embodiments for clarity may also be provided in combination in a single embodiment. Conversely, for the sake of brevity, the various features of the present disclosure that are described in the context of a single embodiment may also be provided separately or in any suitable sub-combination or in any other of the described embodiments of the present disclosure as appropriate. Certain features described in the context of the various embodiments should not be considered essential features of those embodiments unless the embodiment is inoperable without those elements.

[0106] To the extent that the appended claims are written without multiple references, this is done solely to meet the formal requirements of a jurisdiction that does not permit such multiple references. It should be noted that all possible combinations of the implied features are clearly contemplated by making the claims multiple-referenced and should be considered part of the present disclosure.

[0107] Although the present disclosure has been described in connection with specific embodiments thereof, it will be apparent that many alternatives, modifications, and variations will be apparent to those skilled in the art. Accordingly, the present invention is intended to embrace all such alternatives, modifications, and variations that fall within the spirit and broad scope of the appended claims.

Claims

1. A system for testing defects of an optical plate, the optical plate including a plurality of surfaces, the plurality of surfaces including a first end surface and a second end surface and a pair of mutually parallel main outer surfaces for supporting light to propagate through the optical plate by means of internal reflection at the main outer surfaces, the system comprising: a light source that generates light and is deployed close to the optical plate such that the light generated by the light source enters the optical plate near the first end surface and propagates through the optical plate towards the second end surface by means of internal reflection at the main outer surfaces; and a detector device including at least a first detector, the first detector being deployed in association with a first main outer surface of the main outer surfaces and being configured to detect light that is generated by the light source and exits the optical plate through the first main outer surface of the main outer surfaces due to scattering caused by defects of the light propagating through the optical plate by means of internal reflection.

2. The system according to claim 1, wherein, The detector device further includes a second detector deployed in association with a second main outer surface of the main outer surfaces.

3. The system according to claim 1, further comprising: An absorber device including at least one light-absorbing surface, the absorber frame device being for deployment relative to the optical plate such that the at least one light-absorbing surface is associated with a corresponding surface of the surfaces of the optical plate.

4. The system according to claim 3, wherein The plurality of surfaces further includes a first edge surface and a second edge surface, and wherein the at least one light-absorbing surface includes a plurality of light-absorbing surfaces, the plurality of light-absorbing surfaces including: a first light-absorbing surface associated with the first main outer surface of the main outer surfaces, a second light-absorbing surface associated with the second main outer surface of the main outer surfaces, a third light-absorbing surface associated with the second end surface, a fourth light-absorbing surface associated with the first edge surface, and a fifth light-absorbing surface associated with the second edge surface.

5. The system according to claim 1, wherein, The optical plate includes: one or more optical coatings at one or more of the main outer surfaces.

6. The system according to claim 1, wherein The optical plate includes: at least one optical component deployed inside the optical plate between the main outer surfaces.

7. The system according to claim 6, wherein, The at least one optical component includes a plurality of partially reflective surfaces obliquely inclined to the main outer surfaces.

8. The system according to claim 6, wherein, The at least one optical component includes a partially reflective surface parallel to the main outer surfaces.

9. The system according to claim 1, wherein, The optical plate is formed as a stack of a plurality of constituent optical plates.

10. The system according to claim 1, wherein, The optical plate is part of a combined stack of optical plates.

11. The system according to claim 1, further comprising: An integrating sphere including an input region associated with the light source and at least a first output region associated with the first detector.

12. The system according to claim 11, wherein, The first output region is associated with the second end surface of the optical plate.

13. The system according to claim 11, wherein, The first output region is associated with one of the main outer surfaces of the optical plate.

14. The system according to claim 1, further comprising: At least one computer processor electrically associated with the detector device and configured to process a signal generated by the detector device in response to the first detector detecting light generated by the light source and exiting the optical plate to obtain an integrity measurement result of the optical plate.

15. The system according to claim 14, wherein, The integrity measurement result is a count of the number of times the light exiting the optical plate generated by the light source is detected by the first detector, and wherein the at least one processor is further configured to perform a comparison of the count of the number of times of detection with one or more thresholds, and output the availability status of the optical plate based on the comparison.

16. A system for testing for defects in an optical plate, the optical plate including a plurality of surfaces, the plurality of surfaces including a first end surface and a second end surface and a pair of mutually parallel major outer surfaces for supporting the propagation of light through the optical plate by internal reflection at the major outer surfaces, the system comprising: An integrating sphere including an input region and at least a first output region; A light source that generates light and is positioned outside the integrating sphere and adjacent to the input region; And A detector device including a photodetector positioned outside the integrating sphere and adjacent to the first output region, wherein the integrating sphere, the light source, and the detector device are arranged such that: The light generated by the light source enters the optical plate near the first end surface through the input region, and propagates through the optical plate toward the second end surface by internal reflection at the major outer surfaces, and the light reflected from the inner surface of the integrating sphere passes through the output region to reach the photodetector, wherein the light reflected from the inner surface is a portion of the light that propagates through the optical plate by internal reflection at the major outer surfaces, and the portion of the light exits the optical plate through one of the major outer surfaces due to scattering caused by a defect.

17. The system according to claim 16, wherein, The first output region is associated with the second end surface of the optical plate.

18. The system according to claim 16, wherein, The first output region is associated with one of the major outer surfaces of the optical plate.

19. The system according to claim 16, further comprising: An imaging system having at least one image sensor associated with a second output region of the integrating sphere to capture one or more images of an interior portion of the integrating sphere.

20. The system according to claim 16, wherein The integrating sphere is formed by a pair of hemispherical portions that are spatially separated from each other to form an air gap therebetween for accommodating the optical plate.

21. The system according to claim 20, wherein, The air gap defines the input region and the output region.

22. A system for testing for defects in an optical plate, the optical plate including a plurality of surfaces, the plurality of surfaces including a first end surface and a second end surface and a pair of mutually parallel major outer surfaces for supporting the propagation of light through the optical plate by internal reflection at the major outer surfaces, the system comprising: A light source deployed in association with a first major outer surface of the major outer surfaces, the light source being configured to generate light incident on the first major outer surface of the major outer surfaces such that the generated light encounters a defect in the optical plate, and a portion of the generated light undergoes scattering caused by the defect and is thus coupled into the optical plate and propagates toward the first end surface or the second end surface by internal reflection at the major outer surfaces; And A detector, the detector being deployed in association with the first end surface or the second end surface such that the detector detects light that propagates through the optical plate by internal reflection at the main outer surface.

23. A method for testing for defects in an optical plate, the optical plate including a plurality of surfaces, the plurality of surfaces including a first end surface and a second end surface and a pair of mutually parallel main outer surfaces for supporting light to propagate through the optical plate by internal reflection at the main outer surface, the method comprising: Deploying the optical plate relative to a detector device having at least a first detector and a light source such that the first detector is associated with a first main outer surface of the main outer surfaces, and light generated by the light source enters the optical plate near the first end surface and propagates through the optical plate towards the second end surface by internal reflection at the main outer surface; And Detecting light that is generated by the light source and exits the optical plate through one of the main outer surfaces due to scattering caused by a defect.

24. The method according to claim 23, wherein The detector device further includes a second detector, and wherein the optical plate is deployed such that the second detector is associated with a second main outer surface of the main outer surfaces.

25. The method according to claim 23, wherein The optical plate includes: one or more optical coatings at one or more of the main outer surfaces.

26. The method according to claim 23, wherein The optical plate includes: at least one optical component disposed inside the optical plate between the main outer surfaces.

27. The method according to claim 26, wherein, The at least one optical component includes a plurality of partially reflective surfaces that are obliquely inclined with respect to the main outer surface.

28. The method according to claim 26, wherein The at least one optical component includes a partially reflective surface parallel to the main outer surface.

29. The method according to claim 23, wherein The optical plate is formed as a stack of a plurality of constituent optical plates.

30. The method according to claim 23, wherein, The optical plate is part of a combined stack of optical plates.

31. The method according to claim 23, further comprising: Deploying an absorber device including at least one light-absorbing surface such that the at least one light-absorbing surface is associated with a corresponding surface of the surfaces of the optical plate.

32. The method according to claim 31, wherein, The plurality of surfaces further includes a first edge surface and a second edge surface, and wherein the at least one light-absorbing surface includes a plurality of light-absorbing surfaces, the plurality of light-absorbing surfaces including: a first light-absorbing surface associated with a first main outer surface of the main outer surfaces, a second light-absorbing surface associated with a second main outer surface of the main outer surfaces, a third light-absorbing surface associated with the second end surface, a fourth light-absorbing surface associated with the first edge surface, and a fifth light-absorbing surface associated with the second edge surface.

33. The method according to claim 23, wherein, The deployment includes: positioning the optical plate in an integrating sphere having an input region and an output region such that the input region is associated with the light source and the output region is associated with the first detector.

34. The method according to claim 33 further comprises: Capturing one or more images of an internal portion of the integrating sphere by at least one image sensor.

35. The method according to claim 33, wherein, The integrating sphere is formed by a pair of hemispherical parts that are spatially separated from each other to form an air gap therebetween, wherein the deployment includes positioning the optical plate in the air gap.

36. The method according to claim 23, wherein The scattering is caused by at least one flaw at one or both of the major outer surfaces.

37. The method according to claim 36, further comprising: Clean or polish the optical plate to at least partially remove the at least one flaw.

38. The method according to claim 36, wherein, The scattering is caused by at least one flaw including one or more of the following: surface-level flaws or bulk flaws.

39. The method according to claim 38, wherein The surface-level flaws are selected from the group consisting of: recesses, scratches, chips, dust, dirt, debris, one or more particles, non-uniformities, residues of adhesives, rough areas, and discontinuities of the optical coating at one or both of the major outer surfaces.

40. The method according to claim 38, wherein, The bulk flaws are selected from the group consisting of: non-uniformities at one or more internal portions of the optical plate and air bubbles in one or more internal portions of the optical plate.

Images