System and method for testing optical plates for scratches

Abstract

A system and method for testing an optical plate for defects. The optical plate has first and second end faces and a pair of parallel main outer surfaces for supporting the propagation of light through the optical plate by internal reflection at the main outer surfaces. A light source is a light source that generates light and is positioned close to the optical plate such that the light generated by the light source enters the optical plate close to the first end face and propagates through the optical plate toward the second end face by internal reflection at the main outer surfaces. A detector configuration has at least a first detector positioned in association with the first main outer surface and configured to detect light that exits the optical plate through the first main outer surface due to scattering induced by a defect in the light generated by the light source and propagating through the optical plate by internal reflection.

Description

Technical Field

[0001] Cross - reference to Related Applications This application claims priority from U.S. Provisional Patent Application No. 63 / 460,329, filed on April 19, 2023, the disclosure of which is hereby incorporated by reference in its entirety.

[0002] This disclosure relates to testing systems and methods, and in particular, to systems and methods for testing an optical plate for defects through the detection of scattered light.

Background Art

[0003] The optical configurations of 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 called the eye - motion box or EMB). To implement a compact device, the image that will 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 by an optical waveguide (also called a light - transmissive substrate or a light - guiding optical element). The image light from the projector is incident on the optical waveguide, and the optical waveguide guides the image light by internal reflection on the main outer surfaces of the optical waveguide that are parallel to each other, and gradually couples and outputs the image light (e.g., through a partial reflector or a diffraction element embedded in the optical waveguide), thereby magnifying (doubling) the image in at least one dimension and generating a large aperture. Even the smallest defect in the optical waveguide, especially a defect on or near one or more of the parallel main outer surfaces of the optical waveguide, can disrupt the conditions for internal reflection. Thus, the smallest defects in the optical waveguide are of utmost importance for generating a clear and sharp image for the observer. Conventional measurement tools and devices lack the sensitivity required to identify even minor defects in the optical waveguide.

Summary of the Invention

[0004] This disclosure provides a system and method for testing an optical plate for defects through the detection of scattered light.

[0005] According to the teaching of one embodiment of the present disclosure, a system is provided for testing an optical plate for defects. The optical plate includes a plurality of surfaces, including first and second end faces, and a pair of parallel main outer surfaces to support the propagation of light through the optical plate by internal reflection at the main outer surfaces. The system comprises a light source that generates light and is positioned close to the optical plate such that the light generated by the light source enters the optical plate close to the first end face and propagates through the optical plate toward the second end face by internal reflection at the main outer surfaces, and a detector configuration that includes at least a first detector positioned in association with the first main outer surface and configured to detect the light generated by the light source that exits the optical plate through the first main outer surface by scattering induced by a defect in the light propagating through the optical plate by internal reflection.

[0006] Optionally, the detector configuration further includes a second detector deployed in association with the second main outer surface.

[0007] Optionally, the system further comprises an absorber configuration including at least one light-absorbing surface, and the absorber frame configuration is for deploying to an optical plate such that at least one light-absorbing surface is associated with one corresponding surface of the optical plate.

[0008] Optionally, the multiple surfaces further include a first edge surface and a second edge surface, and at least one light-absorbing surface includes multiple light-absorbing surfaces, including a first light-absorbing surface associated with the first main outer surface, a second light-absorbing surface associated with the second main outer surface, 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.

[0009] Optionally, the optical plate includes one or more optical coating layers on one or more of its main outer surfaces.

[0010] Optionally, the optical plate includes at least one optical component disposed inside the optical plate between its main outer surfaces.

[0011] Optionally, at least one optical component includes a plurality of partial reflective surfaces that are obliquely inclined with respect to the main outer surface.

[0012] Optionally, at least one optical component includes a partial reflective surface parallel to the main outer surface.

[0013] Optionally, the optical plate is formed as a stack of multiple constituent optical plates.

[0014] Optionally, the optical plate is part of a stack of bonded optical plates.

[0015] Optionally, the system further comprises an integrating sphere including an input region associated with a light source and at least a first output region associated with a first detector.

[0016] Optionally, the first output region is associated with the second end face of the optical plate.

[0017] Optionally, the first output region is associated with one of the main outer surfaces of the optical plate.

[0018] Optionally, the system further comprises at least one computer processor electrically associated with the detector configuration and configured to process signals generated by the detector configuration in response to the detection by the first detector of light generated by a light source emanating from the optical plate, in order to derive integrity measurements of the optical plate.

[0019] Optionally, the integrity measurement is a count of the number of times the first detector detects light generated by a light source emanating from the optical plate, and at least one processor is further configured to perform a comparison of the detection count with one or more thresholds and output the usability status of the optical plate based on the comparison.

[0020] Furthermore, a system for testing an optical plate for defects is provided according to the teaching of one embodiment of the present disclosure. The optical plate includes a plurality of surfaces, including first and second end faces and a pair of parallel main outer surfaces to support the propagation of light through the optical plate by internal reflection on the main outer surfaces. The system comprises 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 adjacent to the input region, and a detector configuration including a photodetector positioned outside the integrating sphere adjacent to the first output region, wherein the integrating sphere, light source, and detector configuration are configured such that the light generated by the light source passes through the input region, enters the optical plate adjacent to the first end face, propagates through the optical plate toward the second end face by internal reflection on the main outer surfaces, and the light reflected from the inner surface of the integrating sphere passes through the output region toward the photodetector, the light reflected from the inner surface being a proportion of the light propagating through the optical plate by internal reflection on the main outer surfaces that exits the optical plate through one of the main outer surfaces due to scattering induced by a defect.

[0021] Optionally, the first output region is associated with the second end face of the optical plate.

[0022] Optionally, the first output region is associated with one of the main outer surfaces of the optical plate.

[0023] Optionally, the system further comprises 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 the interior portion of the integrating sphere.

[0024] Optionally, the integrating sphere forms an air gap between it to accommodate an optical plate formed by a pair of hemispherical sections that are spatially separated from each other.

[0025] Optionally, an air gap defines the input and output regions.

[0026] Also, in accordance with the teachings of one embodiment of the present disclosure, a system for testing an optical plate for scratches is provided. The optical plate includes a plurality of surfaces including first and second end faces, and a pair of parallel main outer faces for supporting the propagation of light through the optical plate by internal reflection at the main outer faces. The system includes a light source disposed in association with the first main outer face and configured to generate light that strikes the first main outer face, such that a portion of the generated light that collides with a scratch on the optical plate, is coupled to the optical plate, and propagates by internal reflection at the main outer face toward the first end face or the second end face, undergoes the disturbance induced by the scratch; and a detector disposed in association with the first end face or the second end face, the detector being configured to detect light that propagates through the optical plate by internal reflection at the main outer face.

[0027] Also, in accordance with the teachings of one embodiment of the present disclosure, a method for testing an optical plate for scratches is provided. The optical plate includes a plurality of surfaces including first and second end faces, and a pair of parallel main outer faces for supporting the propagation of light through the optical plate by internal reflection at the main outer faces. The method includes disposing the optical plate with respect to a detector configuration having at least the first detector and the light source such that the first detector is associated with the first main outer face and light generated by the light source enters the optical plate proximate the first end face and propagates through the optical plate toward the second end face by internal reflection at the main outer face; and detecting light generated by the light source that exits the optical plate through one of the main outer faces due to scatter induced by the scratch.

[0028] Optionally, the detector configuration further includes a second detector, and disposing the optical plate includes associating the second detector with the second main outer face.

[0029] Optionally, the optical plate includes one or more optical coating layers on one or more of the main outer faces.

[0030] Optionally, the optical plate includes at least one optical component disposed inside the optical plate between the main outer faces.

[0031] Optionally, at least one optical component includes a plurality of partial reflective surfaces that are obliquely inclined with respect to the main outer surface.

[0032] Optionally, at least one optical component includes a partial reflective surface parallel to the main outer surface.

[0033] Optionally, the optical plate is formed as a stack of multiple constituent optical plates.

[0034] Optionally, the optical plate is part of a stack of bonded optical plates.

[0035] Optionally, the method further comprises deploying an absorber configuration including at least one light-absorbing surface, wherein the at least one light-absorbing surface is associated with a corresponding surface of an optical plate.

[0036] Optionally, the multiple surfaces further include a first end face and a second end face, and at least one light-absorbing surface includes multiple light-absorbing surfaces, including a first light-absorbing surface associated with the first main outer surface, a second light-absorbing surface associated with the second main outer surface, a third light-absorbing surface associated with the second end face, a fourth light-absorbing surface associated with the first end face, and a fifth light-absorbing surface associated with the second end face.

[0037] Optionally, deployment involves positioning an optical plate within an integrating sphere having an input region and an output region, where the input region is associated with a light source and the output region is associated with a first detector.

[0038] Optionally, the method further includes capturing one or more images of the interior portion of the integrating sphere using at least one image sensor.

[0039] Optionally, the integrating sphere is formed of a pair of hemispherical sections spatially separated from each other to form an air gap between them, and deployment involves positioning an optical plate within the air gap.

[0040] Optionally, scattering is caused by at least one flaw on one or both of the main outer surfaces.

[0041] Optionally, the method further includes cleaning or polishing the optical plate to remove at least one scratch, at least partially.

[0042] Optionally, scattering is caused by at least one defect, which may include one or more surface-level defects or bulk defects.

[0043] Optionally, surface-level defects are selected from the group consisting of shallow dents, scratches, chips, dust, dirt, fragments, one or more fine particles, heterogeneity, residue from adhesives, rough areas on one or both of the main outer surfaces, and discontinuities in the optical coating on one or both of the main outer surfaces.

[0044] Optionally, bulk defects are selected from the group consisting of heterogeneity in one or more internal parts of the optical plate and air bubbles in one or more internal parts of the optical plate.

[0045] Unless otherwise defined herein, all technical and / or scientific terms used herein have the same meaning as those commonly understood by those skilled in the art to whom this disclosure relates. Similar or equivalent methods and materials may be used in the practice or testing of embodiments of this disclosure, but exemplary methods and / or materials are described below. In case of any conflict, the patent specification, including definitions, shall prevail. In addition, materials, methods, and examples are illustrative and not necessarily intended to be limiting.

[0046] Some embodiments of this disclosure are described herein only as examples, with reference to the accompanying drawings. In referring to the drawings in detail, it is emphasized that the specific details shown are illustrative and for the purpose of illustrative discussion of embodiments of this disclosure. In this regard, the description provided with the drawings will make it clear to those skilled in the art how embodiments of this disclosure may be put into practice.

[0047] Now, turning our attention to the drawings, we see that similar reference numbers or letters indicate corresponding or similar components. The drawing description is as follows: [Brief explanation of the drawing]

[0048] [Figure 1A] This is a schematic side view of a system for testing an optical plate according to one embodiment of the present disclosure, showing a light source for emitting light onto a clean optical plate under test, and a detector associated with the first main outer surface of the clean optical plate for sensing the light emitted by the light source, illustrating the propagation of light by internal reflection through the clean optical plate. [Figure 1B] This is a schematic top view corresponding to Figure 1A. [Figure 2] This is a schematic side view similar to Figure 1A, but it shows that there is a scratch on the optical plate during the test, and that some of the light propagating through the optical plate is deflected outwards from the first main outer surface of the optical plate towards the detector due to internal reflection. [Figure 3] Figure 2 is a schematic side view of a section of the optical plate, illustrating the interaction of propagating light with a scratch that scatters light so that some of the scattered light is deflected outwards from the optical plate towards the detector. [Figure 4] This is a schematic side view similar to Figure 2, but it shows an additional detector deployed to sense a portion of the propagating light deflected from the second main outer surface of the optical plate outwards. [Figure 5A] This is a schematic side view of a system for testing an optical plate having a light-absorbing frame surrounding the optical plate under test, according to one embodiment of the present disclosure. [Figure 5B] This is a schematic top view of a system for testing an optical plate having a light-absorbing frame surrounding the optical plate under test, according to one embodiment of the present disclosure. [Figure 6] Figure 5A is a schematic side view of a system for testing an optical plate similar to that shown, but further shows an integrating sphere that receives the optical plate under test according to one embodiment of the present disclosure. [Figure 7]Figure 6 shows a schematic side view of a system for testing an optical plate similar to that shown in Figure 6, but further illustrates a pair of image sensors forming an image system for capturing an image of the interior portion of an integrating sphere, according to one embodiment of the present disclosure. [Figure 8] Figure 6 shows a schematic side view of a system for testing an optical plate similar to that shown in Figure 6, but in one embodiment of the present disclosure, the integrating sphere is formed from a pair of spatially separated hemispherical sections that form an air gap into which the optical plate under test can be received. [Figure 9] This is a schematic side view of a system for testing an optical plate, which has a scratch on it during testing. It shows a light source associated with the first main outer surface of the optical plate to emit light into the optical plate, and a detector to sense the light emitted by the light source, showing a portion of the light emitted by the light source deflected into the optical plate to propagate through the optical plate by internal reflection. [Figure 10] Figure 9 is a schematic side view of a section of the optical plate, illustrating the interaction between light emitted by a light source and a defect that scatters the light so that some of the scattered light is deflected at a certain angle to propagate through the optical plate by internal reflection. [Figure 11] This is a schematic side view similar to Figure 1A, but the optical plate under test has the form of a light guide optical element having a pair of mutually parallel main outer surfaces and a series of mutually parallel partial reflective inner surfaces that are inclined obliquely with respect to the main outer surfaces. [Figure 12] This is a schematic side view of a system for testing optical plates similar to Figure 1A, but the optical plate under test is formed as a stack of clean constituent optical plates, and an integrating sphere that receives the optical plate under test is also shown. [Figure 13] This is a schematic side view similar to Figure 12, but at least one of the constituent optical plates of the stack under test has at least one defect, causing some of the light propagating through the stack to be deflected out of the stack by internal reflection and reflected from the inner surface of the integrating sphere. [Modes for carrying out the invention]

[0049] Certain embodiments of this disclosure provide a system and method for testing an optical plate for defects through the detection of scattered light.

[0050] The principles and operation of the systems and methods described herein can be better understood by referring to the drawings accompanying this specification.

[0051] Before describing in detail at least one embodiment of this disclosure, it should be understood that in its application, this disclosure is not necessarily limited to the structural details and configurations of components and / or methods described below and / or illustrated in the drawings and / or examples. The present invention can be practiced or carried out in other embodiments or in various ways. First, throughout this specification, references to directions such as up and down, left and right, etc., are made. These references to directions are merely illustrative for illustrating embodiments of this disclosure. Furthermore, it should be noted that optical plates, as illustrated in the drawings, are not necessarily shown to scale.

[0052] The systems and methods of this disclosure can be used to test optical materials of various types and sizes and are particularly valuable when used to test smaller optical plates that are used in the fabrication of optical substrate devices used in near-eye displays (NEDs), head-mounted displays (HMDs), and head-up displays (HUDs), or that are themselves optical substrate devices.

[0053] Referring here to the drawings, Figures 1A and 1B schematically illustrate a system, generally denoted as 10, for testing an optical plate 50 for defects, as taught in one embodiment of the present disclosure. Generally speaking, system 10 includes an illumination configuration 14 having at least one light source 15 for generating (emitting) light, and a detection configuration 20 having at least one detector (i.e., “photosensor” or “photodetector”) 21 for detecting / sensing the light generated (emitting) by the light source 15, in particular the light emitted by the light source 15 that enters the optical plate 50 and subsequently 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 (e.g., computer memory) electrically associated with the detection configuration 20 in order to receive signals from the detection configuration 20 and derive integrity measurements of the optical plate 50 from the received signals.

[0054] The optical plate 50 is formed from a light-transmitting material (e.g., glass). Generally speaking, the optical plate 50 includes a plurality of outer surfaces, including a pair of 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 embodiments illustrated in the drawings, the outer surfaces further include a pair of opposing end faces 56, 58 and a pair of edge faces 60, 62.

[0055] To elaborate, the propagation of light through the optical plate 50 by internal reflection may be total internal reflection (TIR), in which propagating light incident on the main outer surfaces 52, 54 at an angle greater than the critical angle (partially defined by the refractive index of the light-transmitting material and the refractive index of the medium surrounding the optical plate 50, e.g., air, optical coating(s)) is entirely internally reflected on the main outer surfaces 52, 54. Alternatively, propagation by internal reflection can be achieved by optical coatings, such as angle-selective reflective coatings, applied to the main outer surfaces 52, 54 to achieve 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 by internal reflection through a light-transmitting material (such as an optical plate) is referred to as being "guided" or "confined" by internal reflection.

[0056] Returning to Figures 1A and 1B, the illumination configuration 14 and the detector configuration 20 are each positioned close to the optical plate 50 in a particular configuration and orientation. Specifically, the optical plate 50 and the detector configuration 20 are positioned relative to each other such that the detector 21 is associated with one of the main outer surfaces 52 (in this embodiment, the top surface 52, but the detector 21 can be positioned in association with the bottom surface 54) and can detect light escaping from the optical plate 50 through one of the main outer surfaces 52. A focusing optical system (not shown) may be positioned between the detector 21 and the main outer surface of the optical plate 50 to direct the escaping light towards the detector 21. The optical plate 50 and the illumination configuration 14 are positioned relative to each other such that light generated by the light source 15 ( schematically represented in Figure 1A as an illumination beam with a sample ray 16) enters the optical plate 50 in close proximity to one end face 56 (for example, through the end face 56) and propagates through the optical plate 50 along a propagation direction toward the other end face 58 due to internal reflection at the main outer surfaces 52, 54. This arrangement can be achieved by positioning the light source 15 in close proximity to the end face 56. The light propagating through the optical plate 50 by internal reflection is denoted as 17 in the drawings. In the illustrated embodiment, the propagation direction coincides with the elongation direction of the optical plate 50 (the direction along the horizontal dimension in the drawing). When the light 17 reaches the end face 58, the light may, in some cases, be free to exit the optical plate 50 through the surface 58, or in other cases, be absorbed by a light-absorbing coating layer positioned on the end face 58.

[0057] The deployment of the illumination configuration 14 and detector configuration 20 relative to the optical plate 50 may be facilitated by a mounting configuration 12 that receives and positions the optical plate 50. The mounting configuration 12 may be configured to receive the optical plate 50 and position the received optical plate 50 in a specific alignment and orientation relative to the light source 15 and detector configuration 20. Preferably, the light source 15 and detector 21 are positioned in a specific location and orientation relative to the mounting configuration 12, thus providing a specific alignment and orientation of the optical plate 50 relative to the light source 15 and detector configuration 20 when the optical plate 50 is received into the mounting configuration 12. In certain embodiments, the illumination configuration 14 and detector configuration 20 are mechanically coupled to the mounting configuration 12 in a specific location and orientation relative to the mounting configuration 12. In other embodiments, the mounting configuration 12 is mechanically separated from the illumination configuration 14 and detector configuration 20. Although the mounting configuration 12 is illustrated purely schematicly in the drawings, it can be implemented as any suitable mechanical arrangement commonly used to hold optical substrates, such as benchtop optical mounts or substrate holders used in spectroscopy.

[0058] With respect to the illumination configuration 14, it should be noted that the wavelength(s) of the light emitted by the illumination configuration 14 can be any preferred region of the electromagnetic spectrum, such as the visible spectrum, infrared, ultraviolet, etc. In embodiments where one or more light sources 15 are used, the light sources 15 may emit light of the same wavelength or light of different wavelengths. Furthermore, the light sources 15 can generate a broad beam that fills the input aperture of the optical plate 50, and in this respect, it should be noted that the rays of the illumination beam 16 emitted by the light source 15 shown in Figure 1A are only representative of one of many rays across the entire beam. As a result, the propagated light 17 shown in the drawing is only a sample of the beam of propagated illumination corresponding to one of the sample rays of input illumination 16, and the actual propagated light 17 preferably fills the optical plate 50 so that all (or substantially all) of the main outer surface is illuminated by the illumination 17. Alternatively, the light sources 15 can generate a narrower beam of light, and a mechanism for panning and tilting the light sources 15 can be provided to mechanically straddle the input aperture.

[0059] If the optical plate 50 is ideal, it contains no scratches, or only minor or minute scratches, and the conditions for internal reflection are maintained along the entire propagation direction of the optical plate 50, so that the propagating light 17 is guided through the optical plate 50 without leakage or significant loss of intensity through the main outer surfaces 52, 54. 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. As a result, the light 17 is guided through the optical plate 50 by internal reflection without leakage, and the detector 21 detects no light at all (or only a very small amount of light) that passes through the main outer surface 52 to which the detector 21 is associated.

[0060] Next, looking at Figure 2, the optical plate 50 is no longer a "clean plate" and contains one or more defects (synonymously referred to herein as "surface and / or bulk defects in the optical plate," "surface and / or bulk mismatches in the optical plate," or "surface and / or bulk anomalies in the optical plate") that disrupt the conditions for internal reflection, which may manifest as "haze" in the optical plate 50. In particular, these defects, which may be surface and / or bulk defects, cause a portion of the propagating beam 17 to be scattered (i.e., a portion of the beam is scattered by the defect) when the propagating beam 17 collides with the defect (represented as dot 51 in the figure), resulting in the light propagating at an angle that does not satisfy the conditions for internal reflection, and ultimately causing a portion of the propagating beam 17 to exit (escape) the optical plate 50 through one or more of the main outer surfaces 52, 54. In Figure 2, light propagating at an angle that does not satisfy the conditions for internal reflection is represented by a dashed ray, and light that passes through the main outer surface 52 and exits the optical plate 50 (due to scattering) is represented by ray 19 (an extension of the dashed ray). In the illustrated embodiment, ray 19 exits the optical plate 50 at point 63 on the main outer surface 52. In this case, the detector 21, which is positioned in association with the main outer surface 52 from which the light escapes, detects / senses the escaping light 19.

[0061] Figure 3 is a magnified view of a section of the optical plate 50 in Figure 2, illustrating an example of a defect 51 in the optical plate 50 that may cause scattering of the propagating beam 17. Here, the defect 51 is a dent in the main outer surface 54, generally formed as a shallow dent, depression, depression, cavity, or crack on the main outer surface. This dent causes a small portion of the main outer surface 54 to protrude inward into the internal section of the optical plate 50. This protruding portion (i.e., projection) is generally denoted as 53 in Figure 3. As a result of the dent, some of the light 17 striking the projection 53 is reflected (i.e., scattered) in multiple directions by the projection 53, which is schematically represented by scattered rays 18. The rays 18 are scattered in various directions due to variations in the surface shape of the projection 53, so that at least some of the scattered light 18 propagates at angles that do not satisfy the conditions for internal reflection and escapes from the optical plate 50, for example, as a ray 19 through point 63. Some of the scattered light may be at an angle that satisfies the conditions for internal reflection, and therefore, the intensity of a certain proportion of the scattered light may continue to propagate due to internal reflection at the main outer surfaces 52, 54.

[0062] It should be noted that the dents illustrated in Figure 3 are merely illustrative examples of one type of defect that may be present on the optical plate under test, and are illustrative examples of one location of defects on the optical plate under test. Generally, defects on the optical plate under test that can be detected by embodiments of this disclosure may be located in various areas of the optical plate, including the external portion of the optical plate (i.e., one or both of the main outer surfaces 52, 54) and / or the internal portion of the optical plate (i.e., the bulk portion), but in certain particular cases, the defects are more often located in close proximity to the main outer surfaces (i.e., outside and / or inside the optical plate but near the main outer surfaces). Furthermore, embodiments of the present disclosure can detect (i.e. identify) the presence of various types of surface and bulk scratches, including, but not limited to, shallow dents, scratches, chips, dust, dirt, debris, particulate matter, impurities, or adhesive residues located on one or both of the main outer surfaces 52, 54; discontinuities or non-uniformities of the optical coating applied to one or both of the main outer surfaces 52, 54 (including cracks, peeling, flaking, blistering, and clouding of the optical coating); rough areas(s) on one or both of the main outer surfaces 52, 54; non-uniformities in one or more internal parts or areas of the optical plate (i.e., bulk non-uniformities); and gas (e.g., air) bubbles in one or more internal parts or areas of the optical plate. Scratches on an optical plate during testing can occur due to a variety of causes. For example, incomplete or partial polishing of the optical plate may result in rough areas on the main outer surface. For example, polishing may result in shallow dents. Scratches or chips on one or both of the main outer surfaces may occur, for example, due to improper handling of the optical plate (e.g., dropping). Adhesive residue may accumulate on one or both of the main outer surfaces of the optical plate, for example, if the optical plate is formed from multiple material layers that are bonded together. Dust, dirt, debris, and fine particles may accumulate naturally on one or both of the main outer surfaces, for example, over time or during the manufacturing process, and may potentially be removed by cleaning or polishing.Bulk defects such as bubbles or internal inhomogeneities can occur, for example, during the processing of raw materials used to produce optical plates, or during the formation of the glass from which the optical plates are extracted.

[0063] Furthermore, it should be noted that the scattering pattern illustrated in Figure 3 is merely a representation of the scattering patterns that may be caused by scratches on the optical plate. In principle, some of the light in Figure 3 may be scattered downward so as to exit the optical plate through the lower main outer surface 54, which can be detected by a detector deployed in association with the lower main outer surface 54. Thus, although Figures 2 and 3 illustrate escaping light 19 that exits the optical plate 50 through the upper main outer surface 52 at a particular point 63, light escaping from the optical plate 50 due to insufficient conditions for internal reflection caused by scratch-induced scattering may exit the optical plate 50 at various points along any of the main outer surfaces, in which case this can be detected by a detector 21 (or more detectors).

[0064] In response to the detection / sensing of light 19 escaping from the optical plate 50, the detector 21 generates a detector signal. In a particular embodiment, the detector configuration 20 provides these signals to a processing subsystem 26, which may derive an integrity measurement of the optical plate 50 from the received detector signals. In a particular embodiment, the integrity measurement can be used by the processing subsystem 26 to detect / identify the presence of one or more defects in the optical plate. In one exemplary embodiment, the integrity measurement is in the form of a signal count, which the processing subsystem 26 counts the number of detections (performed by the detector 21) of light 19 (generated by the light source 15) emanating from the optical plate 50. In a particular embodiment, if the counted number of detections exceeds a threshold, the processing subsystem 26 may indicate a positive detection / identification of one or more defects. In a particular embodiment, the processing subsystem 26 may compare the counted number of detections to one or more thresholds and output an 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., 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., 50 to 200, the processing subsystem 26 may characterize the optical plate 50 as a “dirty plate”. Depending on the location(s) and / or type(s) of the scratches(s), the “dirty plate” may be cleaned or polished to remove the scratches(s) and then optionally retested. The location of the scratches may be identified using an imaging system, as will be discussed in subsequent parts of this disclosure. In another embodiment, if the signal count is within a third range, e.g., greater than 200, the processing subsystem 26 may characterize the optical plate 50 as an “unusable plate” (i.e., a plate that cannot be cleaned or polished sufficiently to reduce the signal count to the first range), and the optical plate may be discarded or recycled. As is obvious, any number of suitable threshold comparisons and corresponding classifications can be applied.

[0065] Referring now to Figure 4, an embodiment of the system 10 similar to that shown in Figures 1A-2 is illustrated, but the detector configuration 20 includes a second detector 21b positioned in association with the lower main outer surface 54 of the optical plate 50. This configuration allows the detector configuration 20 to detect light emitted from both main outer surfaces of the optical plate 50, effectively doubling the test area that can be inspected by the detector configuration 20, and thus increasing the overall signal-to-noise ratio (SNR) of the detector signal. In the illustrated embodiment, two scratches 51 scatter light 17 propagating by internal reflection, causing light to propagate at angles that do not satisfy the conditions for internal reflection (represented as dashed rays in the figure), and as a result, both main outer surfaces 52, 54 transmit the escaped light 19.

[0066] To reduce the effects of stray light not caused by scattering, the signal intensity of the detector signal can be further improved by employing a light-absorbing configuration or frame on part or all of the outer surface of the optical plate 50. Figures 5A and 5B schematically illustrate non-limiting embodiments of such a configuration, in which the absorber configuration 32 in the form of an absorber frame includes a plurality of light-absorbing surfaces 34, 36, 38, 40, and 42 associated with the outer surfaces 52, 54, 58, 60, and 62, respectively. In one non-limiting embodiment, the light-absorbing surfaces 34, 36, 38, 40, and 42 are implemented as a coating of black paint applied to a base surface that is positioned in relation to the aforementioned surfaces of the optical plate 50. In embodiments in which the propagation of light through the optical plate is due to total internal reflection, it is preferable that a small air gap exists between the light-absorbing surfaces 34, 36 and the respective main outer surfaces 52, 54 so as to maintain the conditions for total internal reflection.

[0067] The embodiments illustrated in Figures 5A and 5B show that each of the outer surfaces 52, 54, 58, 60, and 62 has an associated light-absorbing surface; however, reasonable performance can be achieved with only a portion of the outer surfaces having associated light-absorbing surfaces. For example, in a particular embodiment, only the edge surfaces 60 and 62 may have associated light-absorbing surfaces 40 and 42. It should also be noted that embodiments using an absorber configuration can be used in combination with embodiments where a single detector is deployed (for example, the embodiments shown in Figures 1A and 2).

[0068] The signal-to-noise ratio (SNR) of the detector signal may be further improved by employing an integrating sphere, which may be particularly advantageous in situations where the optical plate contains significant surface scattering centers or bulk scattering centers. Figure 6 schematically illustrates one embodiment in which an optical plate 50 is received within an integrating sphere 70, which is a hollow spherical cavity 73 whose inner surface 71 is coated with a diffuse white reflective coating, as is well known in the art. The integrating sphere 70 includes an input region 72 and at least one output region 74. The input and output regions can be defined as openings or ports of the sphere 70, or alternatively, as light-transmitting regions such as light-transmitting windows. In the illustrated embodiment, a light source 15 is positioned outside the integrating sphere 70, close to the input region 72 of the integrating sphere 70, and light 16 emitted by the light source 15 passes through the input region 72 (closely, for example, through an end face 56) into the optical plate and propagates through the optical plate 50 toward the other end face 58 by internal reflection at the main outer surfaces 52, 54. Similar to the previously described embodiment, when the propagating beam 17 strikes the scratch, a portion of the propagating beam 17 is scattered, and a certain proportion of the propagating beam 17 exits the optical plate 50 through the main outer surfaces 52 and 54. The light 19 that exits the optical plate 50 through the main outer surfaces 52 and 54 due to the scattering induced by the scratch strikes the inner surface 71 of the integrating sphere 70. The struck 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 positioned outside the integrating sphere 70 and close to the output region 74.

[0069] Although the output region 74, and by extension the detector 21, are shown to be located adjacent to the end face 58 of the optical plate 50, the positions of the output region and detector may be arbitrary, as this largely depends on the fact that the emitted light 19 is normally subjected to uniform scattering or the diffusion effect of the integrating sphere, and as a result the light 19 is subjected to multiple reflections from the inner surface 71 of the integrating sphere 70, and therefore the deflection and multiple angles of the emitted light 19.

[0070] Referring now to Figure 7, which is similar to the embodiment in Figure 6, this embodiment includes an image system having at least one image sensor (which may be functionally part of the detector configuration or separate from it), shown in this embodiment as a pair of image sensors 22, 24. The image sensors 22, 24, which may be implemented as cameras, are each positioned outside the integrating sphere 70, close to their respective output regions 76, 78. The image sensors 22, 24 are angled with respect to their respective output regions 76, 78 such that a portion of the internal cavity 73 is within the respective field of view of the image sensors 22, 24, thereby allowing the image sensors 22, 24 to see the internal cavity 73 through the output regions 76, 78 and capture one or more images of the internal 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. The images can be used by a processing subsystem 26 electrically associated with the image sensors 22, 24 of the image system to further characterize the physical location / location of a defect in the optical plate 50. For example, the processing subsystem 26 can correlate the detector count with an image captured by the imaging system to determine the location of a scratch that caused scattering, which resulted in the detector 21 increasing the detector signal count.

[0071] As is clear, the number of image sensors and their placement are not limited to any particular number or configuration. In practice, any suitable number of image sensors (including a single image sensor) and any suitable configuration can be used, but there may be advantages to using a sufficient number of image sensors in a particular configuration so that the combined field of view of the image sensors covers the entire surface area of ​​the main outer surfaces 52, 54 of the optical plate 50.

[0072] Although the absorber configuration 32 is shown in the embodiments illustrated in Figures 6 and 7, it should be noted that the integrating sphere embodiment can be advantageously used without the absorber frame 32.

[0073] The embodiments of the integrating sphere described so far relate to an integrating sphere implemented as a hollow spherical cavity formed as a single piece, but other embodiments are also possible in which the integrating sphere is formed from two separate hemispherical sections. Figure 8 illustrates one such embodiment, in which the integrating sphere 70 is formed from a pair of spatially separated hemispherical sections 80, 82 that form an air gap 84 between them that is large enough to receive an optical plate 50 therein. In this embodiment, the air gap 84 defines the input region 72 and the output region 74.

[0074] The embodiment illustrated in Figure 8 is particularly valuable when used for mass production and testing of optical plates or optical products made from optical plates. Specifically, the dimensions of the air gap 84 allow for the rapid acceptance and replacement of optical plates, thereby enabling rapid sequential analysis of a large number of optical plates.

[0075] The embodiment shown in Figure 8 can be used more advantageously when combined with an imaging system such as the one shown in Figure 7. In particular, if the processing subsystem can use information obtained from the imaging system and detector configuration to identify defects in the same location on a group of optical plates, procedures can be taken to mitigate defects in future batch production. For example, if all the optical plates in a group are pre-treated plates from the same batch, measurement errors can be checked for in the pre-treatment tools used to produce or pre-treat those optical plates, and they may be recalibrated or cleaned (or re-cleaned) to prevent similar defects in future batches.

[0076] The embodiments described so far have concerned detectors deployed to detect / sens light escaping from the optical plate through the main outer surface of the optical plate. However, there may be advantages to employing a detector to detect / sens naturally propagating light 17 emanating from the optical plate 50. In one configuration, a variation of the embodiment illustrated in Figures 1A-2, the detector 21 can be deployed to associate the propagating light 17 through it with an end face 58 through which it naturally emanates from the optical plate 50. In such an embodiment, the detector 21 can be configured to monitor the intensity of the propagating light 17 emanating naturally from the optical plate 50 through the end face 58, and the processing subsystem 26 can derive an integrity measurement based on the monitored intensity. For example, the processing subsystem 26 can determine the baseline (i.e., "nominal") intensity of 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 panned and tilted to cover a range of illumination angles, the intensity can be monitored to identify changes in intensity (e.g., a decrease). For example, if the light source 15 is angled in a first direction so that the beam 16 does not collide with any scratch, the output intensity monitored by the detector 21 will be at its maximum. Subsequently, if the light source 15 is angled in a second direction so that the beam 16 collide with a scratch (or multiple scratches), 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".

[0077] However, it should be noted that monitoring the decrease in intensity requires very high-precision detection and processing, largely due to the fact that leaks that induce a decrease in intensity are usually too small to be accurately detected by conventional electronic devices. Therefore, the embodiments described with reference to Figures 1A-8 are generally more effective and perform better than the alternative embodiments described above. A more effective alternative embodiment is schematically illustrated in Figure 9, which is similar to the embodiments shown in Figures 1A-2, but with the positions of the light source 15 and the detector 21 reversed. Specifically, in the illustrated embodiment, the light source 15 is positioned in association with one of the main outer surfaces 52, and the detector 21 is positioned in association with one of the end surfaces 56. Here, the light source 15 emits a beam of light 16 that strikes the main outer surface 52. If any of the beams 16 strike a scratch, a portion of the beam 16 is scattered in multiple directions by the scratch (i.e., subjected to scratch-induced scattering) and deflected into the optical plate 50. At least a portion of the light is deflected at an angle that satisfies the conditions for internal reflection (one such deflected ray is shown as a dashed ray in Figure 9), and thus at least a portion of the scattered light is coupled to the optical plate 50 and propagates toward the end face 56 by internal reflection at the main outer surfaces 52, 54. Upon reaching the end face 56, the propagated light 17 exits the optical plate 50 naturally / free and is detected / sensed by the detector 21.

[0078] Figure 10 is a magnified view of a section of the optical plate 50 in Figure 9, illustrating an example of a defect 51 (having a projection 53) in the optical plate 50 that causes scattering of light 16, thereby coupling a certain proportion of the light 16 to the optical plate 50 by internal reflection. As illustrated, some of the light 16 that strikes the projection 53 is reflected (i.e., scattered) in multiple directions by the projection 53, which is schematically represented by scattered rays 18. The rays 18 are scattered in various directions due to the change in the surface shape of the projection 53, so that at least some of the scattered light 18 propagates at an angle that satisfies the conditions for internal reflection, coupling within the optical plate 50 (i.e., guided / trapped within the optical plate 50 by internal reflection), and thereby propagating toward the end face 56 by internal reflection at the main outer surfaces 52, 54.

[0079] It is clear that the detector 21 can be deployed in association with the other end face 58 instead of being deployed in association with end face 56. Alternatively, a pair of detectors can be deployed, each associated with end faces 56 and 58, respectively. It is also clear that one or both of the main outer surfaces 52 and 54 may have a light source 15 deployed in association with it, and one or more detectors 21 may be positioned accordingly.

[0080] In the embodiments illustrated in Figures 9 and 10, the light source 15 may be configured to emit wide-angle dispersed light so that the struck beam 16 interacts with a wide area of ​​the main outer surface 52. In certain embodiments, a scanning configuration, such as a scanning mirror, may be deployed adjacent to the light source 15 to generate a wide beam. The light source 15 may be mounted on a mechanical sliding configuration, such as an electric mount, to allow lateral movement of the light source 15 along the elongation direction of the optical plate 50. However, it should be noted that light 16 from the light source 15 that strikes the main outer surface 52 at a certain angle of incidence and does not interact with any scratches may be coupled to the optical plate 50 and confined by internal reflection due to the angle of incidence of the struck light. Therefore, care must be taken to ensure that the light 16 emitted by the light source 15 does not strike the main outer surface 52 at an angle of incidence such that only the light that interacts with scratches is confined within the optical plate by internal reflection.

[0081] The embodiments described above with reference to Figures 9 and 10 may be combined with other embodiments, such as the embodiments described with reference to Figure 2. For example, an embodiment may be devised in which a first light source may be deployed in association with a first end face 56 or a second end face 58, a first detector may be deployed in association with an upper main outer surface 52 or a lower main outer surface 54 to sense light emitted by the first light source that has escaped internal reflection due to a scratch or multiple scratches, a second light source may be deployed in association with an lower main outer surface 54 or an upper main outer surface 52 to illuminate the optical plate, and a second detector may be deployed in association with a second end face 58 or a first end face 56 to sense light emitted by the second light source that is trapped within the optical plate by internal reflection and deflected into the optical plate by a scratch or multiple scratches. In such embodiments, the pair of light sources may operate asynchronously such that the pair of light sources alternately repeat the light-emitting state (i.e., only one of the two light sources illuminates at a time). In such a configuration, if a light-absorbing frame is used, it may be advantageous to employ a movable member that moves the light-absorbing surface associated with the main outer surface to which the second light source is associated away from that main outer surface when the second light source emits light. Alternatively, the pair of light sources may emit light simultaneously.

[0082] Optical plates that can be tested using the systems and methods according to embodiments of this disclosure can take on a variety of forms. In one embodiment, the optical plate is a sample of optical material that has been pre-treated (e.g., cleaned, cut, polished, etc.) in preparation for use as a raw material for constructing optical substrate devices such as light guide optical elements (LOEs) available from Lumus Ltd. of Israel for use in near-eye displays (NEDs), head-mounted displays (HMDs), or head-up displays (HUDs). In certain embodiments, the pre-treatment may include applying one or more layers of optical coating to the main outer surface of the optical plate such that the main outer surface of the optical plate includes the optical coating. A non-limiting example of the optical coating is an angle-selective reflective coating, which can provide conditions for internal reflection.

[0083] In other embodiments, the optical plate may include one or more embedded optical elements. For example, in a particular embodiment, the optical plate may include a partial reflective surface or polarizing element embedded within the optical plate parallel to the main outer surface of the optical plate and partially extending in the elongation direction of the optical plate. In other embodiments, the optical plate is itself an LOE with a series of mutually parallel partial reflective inner surfaces embedded therein, which are inclined obliquely to the main outer surface of the LOE or obliquely to the elongation direction of the LOE and partially traverse 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 scratches or other defects in the LOE. Figure 11 shows an embodiment of system 10 used to test an optical plate mounted as an LOE, where the LOE includes a series of mutually parallel partial reflective inner surfaces 66 that traverse the LOE along the elongation direction and are inclined obliquely to the main outer surfaces 52, 54. It is clear that the location of the light source 15 and the orientation of the partial reflective surfaces 66 provide information useful in determining where to deploy the detector 21. For example, in the illustrated configuration, the incident light 16 from the left end face 56 is coupled with a specific orientation of the partial reflective surface 66, causing a certain percentage of the light 17 propagating through the LOE by internal reflection to be deflected out of the LOE towards the lower main outer surface 54. Therefore, in this test configuration, the detector 21 should be positioned in association with the upper main outer surface 52. If the light source 15 is positioned close to the right end face 58 and the partial reflective surface 66 maintains the same orientation, a certain percentage of the light 17 propagating through the LOE by internal reflection will be deflected out of the LOE towards the upper main outer surface 52, so the detector 21 needs to be positioned in association with the lower main outer surface 54.

[0084] In further embodiments, the optical plate under test may be formed as a stack of constituent optical plates, and each plate in the stack may be configured as an optical plate 50. The constituent optical plates may be aligned and joined together, for example, using an optical adhesive applied to some or all of the main outer surfaces of the constituent optical plates. In such embodiments, the main outer surfaces of the constituent optical plates form the main inner surfaces of the stack of joined plates, except for the upper main outer surfaces of the upper optical plate of the stack and the lower main outer surfaces of the lower optical plate of the stack, which form the upper and lower main outer surfaces of the stack, respectively.

[0085] The optical adhesive used to bond the constituent optical plates may or may not be a refractive index-matching adhesive. If the optical adhesive is refractive index-matching, the stack of optical plates behaves as a thick optical plate with an optical coating embedded inside, and light can propagate by internal reflection between the main outer surfaces of the stack. If 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 the critical angle, each optical plate in the stack behaves like an optical plate in air; that is, at each optical plate, light incident on the main outer surface of the optical plate at an angle greater than the critical angle is confined between the main outer surfaces by total internal reflection. In such a case, scratches on the optical plates in the stack can cause scattering, resulting in the loss of the condition for total internal reflection at that optical plate, and the light exits that optical plate and passes through adjacent optical plates in the stack until it completely exits the stack. In embodiments in which such a stack of optical plates is tested, it may be advantageous to employ an illumination configuration with multiple light sources. For example, the lighting configuration may include a light source for each optical plate in the stack, with each light source providing input illumination to a corresponding optical plate in the stack. Alternatively, multiple light sources may be provided, in which case each light source provides input illumination to a different group of optical plates in the stack. In practice, the stack can be formed from any number of two or more optical plates, as long as the geometric shape of the lighting configuration is appropriately adapted.

[0086] As is clear, any of the embodiments described above can be used to test a stack of such constituent optics. As one non-limiting embodiment, Figure 12 shows an optics plate 50' formed from a stack of clean constituent optics plates 50 bonded together with refractive index-matched optical adhesive, deployed in a test setup similar to the setup shown in Figure 6 (but without the absorption frame 32). Here, the optics plate 50' behaves like a thicker version of the optics plate 50. Thus, light 17 propagates through the optics plate 50' by internal reflection between the main outer surfaces 52, 54 of the optics plate 50' / stack, and none of the internally reflected light 17 escapes through the main outer surfaces 52, 54 (due to not scattering because there are no scratches). Figure 13 illustrates the opposite example, where the optics plate 50' itself has at least one scratch because at least one of the constituent optics plates 50 in the stack has at least one scratch. Here, at least a portion of the internally reflected light 17 escapes as light 19 through one or more of the main outer surfaces 52 and 54.

[0087] As described above, the systems and methods of the present disclosure are applicable to testing optical plates of various sizes and are particularly valuable when used to test smaller optical plates that are used in the manufacture of optical substrate devices used in small form factor near-eye displays (NEDs), head-mounted displays (HMDs), or head-up displays (HUDs), or that are optical substrate devices themselves. Nevertheless, the systems and methods of the present disclosure can be used to test any sample of optical material that is a light-transmitting material having a pair of parallel main outer surfaces capable of supporting the propagation of light by internal reflection through it, such as large optical plates such as automotive windshields, as well as portions of plate glass used as part of windows and / or doors.

[0088] The descriptions of the various embodiments of this disclosure have been presented for illustrative purposes only and are not intended to be exhaustive or to limit the embodiments disclosed. Many modifications and variations made without departing from the scope and spirit of the described embodiments will be apparent to those skilled in the art. The terms used herein have been selected to best describe the principles of the embodiments, their practical applications or technical improvements to the technology available on the market, or to enable those skilled in the art to understand the embodiments disclosed herein.

[0089] As used herein, the singular forms "a," "an," and "the" also have plural meanings unless the context clearly indicates otherwise.

[0090] The term “exemplary” is used herein to mean “presented as an example, case, or illustration.” Any embodiment described as “exemplary” should not necessarily be construed as being preferable or advantageous to other embodiments, and / or preclude the incorporation of features from other embodiments.

[0091] For clarity, certain features of the Disclosure described in the context of separate embodiments may also be provided in combination in a single embodiment. Conversely, various features of the Disclosure described in the context of a single embodiment may also be provided individually, in any preferred partial combination, or as suitable for any other described embodiment of the Disclosure. Certain features described in the context of various embodiments are not considered essential features of those embodiments unless those embodiments would not function without those elements.

[0092] In some cases, the attached claims may be drafted without multiple dependencies; this is done solely to comply with the formal requirements of jurisdictions that do not permit such multiple dependencies. It should be noted that all possible combinations of features that would be suggested by making the claims multiple dependents are explicitly assumed and should be considered part of this disclosure.

[0093] While this disclosure has been described in conjunction with its specific embodiments, it is obvious that many alternatives, modifications, and variations are apparent to those skilled in the art. Therefore, it is intended to encompass all such alternatives, modifications, and variations that fall within the spirit and broad scope of the appended claims.

Claims

1. A system for testing an optical plate for defects, wherein the optical plate comprises a plurality of surfaces, the plurality of surfaces comprising first and second end faces, and a pair of parallel main outer surfaces, the pair of parallel main outer surfaces for supporting the propagation of light through the optical plate by internal reflection at the main outer surfaces, and the system, A light source that generates light, the light source being positioned close to the optical plate such that the light generated by the light source enters the optical plate close to the first end face and propagates through the optical plate toward the second end face by internal reflection on the main outer surface, A system comprising a detector configuration including at least a first detector, which is arranged in association with the first main outer surface and configured to detect light emitted from the optical plate through the first main outer surface due to scattering induced by scratches in the light generated by the light source and propagating through the optical plate by internal reflection.

2. The system according to claim 1, wherein the detector configuration further includes a second detector arranged in relation to the second main outer surface.

3. The system according to claim 1, further comprising an absorber configuration including at least one light-absorbing surface, wherein the absorber frame configuration is for positioning on the optical plate such that the at least one light-absorbing surface is associated with a corresponding surface among the surfaces of the optical plate.

4. The system according to claim 3, wherein the plurality of surfaces further include 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 which include a first light-absorbing surface associated with the first main outer surface, a second light-absorbing surface associated with the second main outer surface, 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 coating layers on 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 disposed 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 partial reflective surfaces that are inclined obliquely with respect to the main outer surface.

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

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 bonding 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 face 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 configuration and configured to process a signal generated by the detector configuration in response to the detection by the first detector of light generated by the light source emanating from the optical plate, in order to derive an integrity measurement of the optical plate.

15. The system according to claim 14, wherein the integrity measurement is a count of the number of times the first detector has detected the light generated by the light source that is emitted from the optical plate, 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 to output the usability status of the optical plate based on the comparison.

16. A system for testing an optical plate for defects, wherein the optical plate comprises a plurality of surfaces, the plurality of surfaces comprising first and second end faces, and a pair of parallel main outer surfaces, the pair of parallel main outer surfaces for supporting the propagation of light through the optical plate by internal reflection at the main outer surfaces, and the system 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 in close proximity to the input region, The detector configuration includes a photodetector positioned outside the integrating sphere and in close proximity to the first output region, The integrating sphere, the light source, and the detector configuration are configured such that light generated by the light source passes through the input region, approaches the first end face and enters the optical plate, propagates through the optical plate toward the second end face by internal reflection on the main outer surface, and the light reflected from the inner surface of the integrating sphere passes through the output region to the photodetector, wherein the light reflected from the inner surface is a certain proportion of the light that propagates through the optical plate by internal reflection on the main outer surface and exits the optical plate through one of the main outer surfaces due to scattering induced by a scratch.

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

18. The system according to claim 16, wherein the first output region is associated with one of the main 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 for capturing one or more images of the internal portion of the integrating sphere.

20. The system according to claim 16, wherein the integrating sphere is formed of a pair of hemispherical sections spatially separated from each other, with an air gap formed between them to receive 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 an optical plate for defects, wherein the optical plate comprises a plurality of surfaces, the plurality of surfaces comprising first and second end faces, and a pair of parallel main outer surfaces, the pair of parallel main outer surfaces for supporting the propagation of light through the optical plate by internal reflection at the main outer surfaces, and the system A light source deployed in association with the first main outer surface, wherein the light source is configured to generate light that strikes the first main outer surface, and a certain proportion of the generated light is subjected to scattering induced by the scratch, such that the generated light collides with a scratch on the optical plate, fuses with the optical plate, and propagates toward the first or second end face by internal reflection on the main outer surface, A detector arranged in association with the first end face or the second end face, wherein the detector detects the light propagating through the optical plate by internal reflection on the main outer surface, A system equipped with these features.

23. A method for testing an optical plate for defects, wherein the optical plate comprises a plurality of surfaces, the plurality of surfaces comprising first and second end faces, and a pair of parallel main outer surfaces, the pair of parallel main outer surfaces for supporting the propagation of light through the optical plate by internal reflection at the main outer surfaces, and the method The present invention relates to a detector configuration having at least a first detector and a light source, wherein the first detector is associated with the first main outer surface, and light generated by the light source enters the optical plate in close proximity to the first end surface, and propagates through the optical plate toward the second end surface by internal reflection at the main outer surface. A method comprising detecting light generated by the light source that exits the optical plate through one of the main outer surfaces due to scattering induced by a scratch.

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

25. The method according to claim 23, wherein the optical plate includes one or more optical coating layers on 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 partial reflective surfaces that are inclined obliquely with respect to the main outer surface.

28. The method according to claim 26, wherein the at least one optical component includes a partial 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 bonding stack of optical plates.

31. The method according to claim 23, further comprising arranging an absorber configuration including at least one light-absorbing surface, wherein the at least one light-absorbing surface is associated with a corresponding surface among the surfaces of the optical plate.

32. The method according to claim 31, wherein the plurality of surfaces further include 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 which include a first light-absorbing surface associated with the first main outer surface, a second light-absorbing surface associated with the second main outer surface, 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 an optical plate within an integrating sphere having an input region and an output region, wherein 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 comprising capturing one or more images of the interior portion of the integrating sphere by at least one image sensor.

35. The method according to claim 33, wherein the integrating sphere is formed of a pair of hemispherical sections spatially separated from each other to form an air gap between them, and the deployment includes positioning the optical plate within the air gap.

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

37. The method according to claim 36, further comprising cleaning or polishing the optical plate to remove at least one of the scratches in part.

38. The method according to claim 36, wherein the scattering is caused by at least one defect, which includes one or more surface-level defects or bulk defects.

39. The method according to claim 38, wherein the surface-level scratches are selected from the group consisting of shallow dents, scratches, chips, dust, dirt, fragments, one or more fine particles, heterogeneity, adhesive residue, rough areas on one or both of the main outer surfaces, and discontinuities in the optical coating on one or both of the main outer surfaces.

40. The method according to claim 38, wherein the defects in the bulk are selected from the group consisting of heterogeneity in one or more internal parts of the optical plate and air bubbles in one or more internal parts of the optical plate.

Images