Method and system for verifying parallelism between internal facets

Abstract

This document discloses a method comprising: (i) providing a translucent sample comprising nominally parallel internal facets that are approximately orthogonal to an external surface of the sample; (ii) providing an optical element having a refractive index approximately equal to that of the sample and comprising an external first surface and an external second surface inclined at an acute angle relative to the first surface; (iii) positioning the second surface of the optical element adjacent to the first surface of the sample; (iv) illuminating the first surface of the optical element approximately perpendicularly to it; (v) sensing the beam of light after it has passed through the optical element, been transmitted into the sample, been reflected once from the internal facets, and exited the sample; and (vi) calculating a parallelism deviation between the internal facets based on the sensed data.

Description

Technical Field

[0001] This disclosure generally relates to methods and systems for measuring samples, including internal facets. Background Technology

[0002] Some optical waveguides include nominally parallel reflective internal facets. Current technologies require high-end optical components to verify the parallelism of such facets with high precision. Therefore, there is an unmet need in the art for a simple and readily implementable measurement technique that avoids the use of high-end optical components, thus addressing the needs of large-scale production. Summary of the Invention

[0003] According to some embodiments of this disclosure, aspects of this disclosure relate to methods and systems for measuring samples including internal facets. More specifically, but not exclusively, according to some embodiments of this disclosure, aspects of this disclosure relate to optically based methods and systems for measuring samples including a plurality of nominally parallel internal facets. More specifically, according to some embodiments of this disclosure, aspects of this disclosure relate to optically based methods and systems for measuring reflective waveguides including a plurality of nominally parallel internal facets, which are nominally orthogonal to the main surface of the waveguide.

[0004] Reflective waveguides are used in various displays such as head-up displays, smartphones, compact displays, 3D displays (stereoscopic displays), and compact beam expanders. A reflective waveguide comprises multiple nominally parallel internal facets across the output section of the waveguide. Light propagating from the input section of the waveguide along the direction of the output section (by total internal reflection) is gradually coupled out of the waveguide through partial reflection and transmission at each internal facet. The high parallelism between the internal facets (especially adjacent internal facets) helps ensure a sharp and clear image (free from ghosting or blurring) on ​​the display.

[0005] Various methods for monitoring the parallelism of internal facets in a stack of boards before the reflective waveguide is cut into individual units are known in the art. However, the parallelism of the internal facets is likely to change from these early stages of production until the finished product (i.e., until the production of the reflective waveguide is complete).

[0006] There is an unmet need in the art for improved methods to verify the parallelism of internal facets in (finished) reflective waveguides, as well as in later stages of their production. Advantageously, this application discloses a fast, simple, and accurate method for verifying the parallelism between internal facets of a reflective waveguide. This application also discloses a system capable of implementing the disclosed method, which advantageously avoids the use of high-end and / or complex components.

[0007] Therefore, according to one aspect of some embodiments, an optical-based method is provided for verifying the parallelism between internal facets of a sample. The method includes the following stages:

[0008] - Provide a sample, which includes samples with a refractive index n s The light-transmitting substrate and two or more internal facets. The internal facets are embedded in the substrate and are nominally parallel, and are approximately orthogonal to the outer and flat first surface of the sample.

[0009] - Provides approximately equal to n s The first optical element (FOE) has a refractive index of [missing information]. The FOE includes an external and flat first surface and an external and flat second surface. The second surface of the FOE is opposite to the first surface of the FOE and is inclined at an acute angle to the first surface.

[0010] Position the sample and FOE such that the second surface of the FOE is adjacent to the first surface of the sample.

[0011] - Project a first plurality of beams onto the first surface of the FOE approximately perpendicularly (i.e., approximately orthogonally) to the first surface.

[0012] - A second plurality of beams are obtained, each of the first plurality of beams passing through (i.e. through) the FOE, being transmitted into the sample and being reflected once from the internal facet before exiting the sample.

[0013] - Sensing (i.e., measuring) a second multiple beam.

[0014] - Based on the sensed data (obtained in sensing a second or more beams), calculate at least one parallelism deviation between at least some of the internal facets.

[0015] According to some implementations of this method, FOE has an equal to n s The refractive index.

[0016] According to some embodiments of the method, a first plurality of beams are projected perpendicularly onto a first surface of the FOE.

[0017] According to some embodiments of the method, the stage of calculating parallelism deviation includes: calculating the angular deviation between the beams in the second plurality of beams (i.e., the angle between such beams).

[0018] According to some embodiments of the method, the beams in the first plurality of beams constitute complementary portions of the collimated extended beam.

[0019] According to some implementations of this method, the extended beam is monochromatic.

[0020] According to some embodiments of the method, the extended beam is an extended laser beam.

[0021] In some embodiments of this method, the FOE is a prism. In some such embodiments, the FOE is a triangular prism.

[0022] According to some embodiments of the method, the sample is shaped as a thin plate or an elongated box.

[0023] According to some implementations of this method, the sample is a one-dimensional or two-dimensional reflective waveguide.

[0024] According to some embodiments of this method, in the stage of sensing the second plurality of light beams, an image sensor is used to sense the light beams in the second plurality of light beams. The sensing data thus obtained includes the measured intensity of the pixels constituting the light spots on the image sensor. Each light spot is caused by a corresponding light beam in the second plurality of light beams.

[0025] According to some embodiments of the method, the stage of sensing the second plurality of beams includes observing a beam in the second plurality of beams through an eyepiece. The beam in the second plurality of beams appears as a spot of light relative to a scale line on the eyepiece.

[0026] According to some implementations of this method, the stage of calculating the parallelism deviation includes: calculating ε avg and / or ε max ε avg equal ε max Equal to max{ε ij} i，j＞i or It is a set of two-dimensional vectors specifying the positions of the i-th and j-th light spots (formed by the beams in the second plurality of beams) on the image sensor or relative to the scale lines of the eyepiece. N is the number of internal facets. M is the number of distinct pairs of internal facets (i.e., M = N·(N-1) / 2). f is the focal length of the focusing lens or focusing lens assembly configured to focus the returned beam onto the image sensor or eyepiece.

[0027] According to some embodiments of the method, each of the first plurality of beams continues to be reflected from a corresponding internal facet in the sample.

[0028] According to some embodiments of the method, the beams in the first plurality of beams are projected continuously, so that the internal facets are examined one at a time.

[0029] According to some implementations of this method, continuous projection is achieved using a slit or aperture optical mask that can be translated and / or multiple shutters.

[0030] According to some implementations of this method, when calculating the parallelism deviation, the parallelism deviation between pairs of internal small planes in two or more internal small planes is calculated.

[0031] According to some embodiments of the method, the paired internal facets include a pair of adjacent internal facets.

[0032] According to some implementations of this method, calculating the parallelism deviation between pairs of internal facets includes: calculating two sets of deviations, i.e., pitch deviations {ε}, between the internal facets of each pair of internal facets in the pair of internal facets. ij,p} i,j and / or roll deviation {ε ij,r} i,j Indices i and j involve distinct pairs of internal facets (within the paired internal facets). ε ij,p and ε ij,r These are the pitch and roll deviations between the i-th and j-th inner minor planes, respectively. According to some such implementations, these deviations are respectively transmitted via ε... ij,p =δ ij,p / (2n s )=(x i -x j ) / (2n s ·f) and ε ij,r =δ ij,r / (2n s )=(y i -y j ) / (2n s ·f) to calculate ε ij,p and ε ij,r δ ij,p δ is the pitch deviation between the i-th beam in the second plurality of beams caused by reflection from the i-th internal small plane and the j-th beam in the second plurality of beams caused by reflection from the j-th internal small plane. ij,r It is the roll deviation between the i-th beam and the j-th beam in the second plurality of beams. This is a set of two-dimensional vectors specifying the position of the light spot on the image sensor or relative to the scale lines of the eyepiece. Index k marks the light beam. N is the number of internal facets. f is the focal length of the focusing lens or focusing lens assembly configured to focus one of the second or more light beams onto the image sensor or eyepiece.

[0033] According to some implementations of this method, the stage of calculating parallelism deviation includes calculating the maximum pitch deviation (i.e., the range of pitch deviation) ε between the internal facets. max，p =(max{x i} i -min{x i} i ) / (2n s The maximum roll deviation (i.e., the range of roll deviation) ε between f) and / or the internal facets max，r =(max{y i} i -min{y i} i ) / (2n s ·f). This is a set of two-dimensional vectors specifying the position (e.g., center point) of the spot caused by the second or more beams on the image sensor or relative to the scale lines of the eyepiece. Index i marks this point. N is the number of internal facets. f is the focal length of the focusing lens or focusing lens assembly configured to focus the second or more beams onto the image sensor or eyepiece.

[0034] According to some embodiments of the method, during the stage of positioning the sample and FOE, the sample and FOE are positioned such that the second surface of the FOE is parallel to the first surface of the sample.

[0035] According to some embodiments of the method, the sample and the FOE are positioned such that a first region on a first surface of the sample is in complete contact with a second surface of the FOE. The first region is defined by a portion of the sample including internal facets.

[0036] According to some implementations of this method, in the stage of calculating parallelism deviation, the parallelism deviation between pairs of adjacent internal small planes in two or more internal small planes is calculated.

[0037] According to some embodiments of the method, in the stage of calculating parallelism deviation, the parallelism deviation of one of the two or more inner planes relative to a reference inner plane (e.g., the outermost inner plane) is calculated.

[0038] According to some embodiments of the method, the first surface of the FOE is coated with an anti-reflective coating.

[0039] According to some embodiments of the method, the method further includes applying a shape-plastic interface between the FOE and the sample. The shape-plastic interface has a refractive index substantially the same as that of the substrate. According to some such embodiments, the shape-plastic interface can be a liquid, gel, or paste.

[0040] According to some embodiments of the method, an autocollimator is used to generate a first plurality of beams and to focus a beam from a second plurality of beams onto a photosensitive element, which is used to sense the second plurality of beams.

[0041] According to some embodiments of the method, the second plurality of beams includes beams that pass through the first surface of the sample and return from the sample via FOE.

[0042] According to some embodiments of the method, the sample includes an external, flat second surface opposite to the first surface of the sample. Before exiting the sample via the first surface, the returning beam is reflected away from the second surface.

[0043] According to some embodiments of this method, the internal plane of the sample is orthogonal to the first surface of the sample. The second surface of the sample is parallel to the first surface of the sample.

[0044] According to some embodiments of this method, adjacent internal facets of the sample are spaced apart at regular intervals. The first tilt angle is equal to approximately (90° - arctan(2d1 / d2)), that is, the tilt angle σ is equal to 90 degrees minus arctan(2d1 / d2). d1 is the distance between the first surface and the second surface of the sample. d2 is the distance between adjacent internal facets of the sample.

[0045] According to some implementations of the method, the first tilt angle makes the ratio of the power of the second plurality of beams to the power of the first plurality of beams approximately maximum.

[0046] According to some embodiments of the method, the sample includes an external and flat second surface opposite to the first surface of the sample. The second plurality of light beams includes light beams emitted from the sample via the second surface.

[0047] According to some embodiments of the method, the method further includes providing a second optical element (SOE) prior to the stage of projecting the first plurality of beams. The SOE has approximately equal to n s The refractive index is . The SOE includes an external and flat first surface and an external and flat second surface. The second surface of the SOE is opposite to the first surface of the SOE and is inclined at an acute second tilt angle relative to the first surface of the SOE. The stage of positioning the sample and the FOE further includes positioning the SOE and / or the sample such that the second surface of the SOE is adjacent to the second surface of the sample. The second plurality of beams includes beams that, after exiting from the sample via the second surface of the sample and being transmitted into the SOE, exit from the SOE via the first surface of the SOE. According to some such embodiments, the SOE has a refractive index equal to n. s The refractive index.

[0048] According to some embodiments of the method, during the stage of positioning the sample and FOE, the sample, FOE, and SOE are positioned such that the second surface of the FOE is parallel to the first surface of the sample and the second surface of the SOE is parallel to the second surface of the sample.

[0049] According to some embodiments of the method, the second tilt angle is approximately equal to the first tilt angle, such that each of the second plurality of beams exits the SOE approximately perpendicular to the first surface of the SOE. According to some such embodiments, the second tilt angle is equal to the first tilt angle.

[0050] According to some embodiments of the method in which an internal facet of the sample is orthogonal to a first surface of the sample and a second surface of the sample is parallel to the first surface of the sample, adjacent internal facets of the sample are spaced apart at regular intervals. Each of the first and second tilt angles is equal to approximately (90° - arctan(d1 / d2)), that is, the tilt angle σ is equal to 90 degrees minus arctan(d1 / d2). d1 is the distance between the first and second surfaces of the sample. d2 is the distance between adjacent internal facets of the sample.

[0051] According to some embodiments of the method, the first tilt angle and the second tilt angle make the ratio of the power of the second plurality of beams to the power of the first plurality of beams approximately maximum.

[0052] In some embodiments of this method, the SOE is a prism. In some such embodiments, the SOE is a triangular prism.

[0053] According to some embodiments of the method, the sample, FOE, and SOE are positioned such that a first region on a first surface of the sample is in complete contact with a second surface of the FOE, and a second region of the sample is in complete contact with a second surface of the SOE. The first and second regions are defined by a portion of the sample including internal facets. The second region is opposite to the first region.

[0054] According to some embodiments of the method, the first surface of the SOE is coated with an anti-reflective coating.

[0055] According to some embodiments of the method, the method further includes applying shape-plastic interfaces between the FOE and the sample, and between the SOE and the sample. The shape-plastic interfaces have approximately the same refractive index as the substrate. According to some such embodiments, the shape-plastic interfaces can be liquids, gels, or pastes.

[0056] According to one aspect of some embodiments, an optical-based system for measuring a sample having a refractive index of n is provided. sThe system includes a substrate and two or more internal facets embedded in the substrate, nominally parallel and approximately orthogonal to a flat first surface relative to the exterior of the sample. The system includes a first optical element (FOE) and an optical device comprising a light source, optical apparatus, and a photosensing component. The FOE has approximately equal to n. s The FOE has a refractive index and includes an external and flat first surface and an external and flat second surface. The second surface of the FOE is opposite to the first surface of the FOE and is inclined at an acute first angle relative to the first surface of the FOE. The optical device is configured such that the sample and / or the FOE is positioned such that (i) the second surface of the FOE is adjacent to the first surface of the sample, and (ii) when so positioned (i.e., when the second surface of the FOE is adjacent to the first surface of the sample), a first plurality of light beams generated by the light source will illuminate the first surface of the FOE approximately perpendicular to the first surface of the FOE. The FOE is also configured to focus a second plurality of light beams, which are the first plurality of light beams passing through the FOE, transmitted into the sample, and reflected once from the internal facets before exiting the sample, onto a photosensitive element, thereby enabling the measurement of the angular deviation between the light beams in the second plurality of light beams. The angular deviation between the light beams in the second plurality of light beams indicates the parallelism deviation between the internal facets.

[0057] According to some implementations of the system, FOE has an equal to n s The refractive index.

[0058] According to some embodiments of the system, the optical setup is configured such that the second surface of the FOE is positioned adjacent to the first surface of the sample, such that a first plurality of light beams generated by a light source will illuminate the first surface of the FOE perpendicularly to the first surface of the FOE.

[0059] According to some embodiments of the system, the optical device includes a collimating lens or collimating lens assembly configured to collimate a light beam generated by a light source, thereby preparing a first plurality of light beams.

[0060] According to some implementations of this system, the light source is a monochromatic light source.

[0061] According to some implementations of this system, the light source is a laser light source.

[0062] According to some embodiments of the system, the optical device includes a focusing lens or focusing lens assembly configured to focus a beam from a second plurality of beams onto a photosensitive element.

[0063] According to some embodiments of the system, the light-sensing component includes an image sensor configured to sense a second plurality of light beams.

[0064] According to some implementations of the system, the light sensing component is or includes a camera device.

[0065] According to some implementations of the system, the light-sensing component includes an eyepiece assembly.

[0066] According to some implementations of the system, the optical device is configured to position the sample and / or FOE such that the second surface of the FOE is parallel to the first surface of the sample.

[0067] According to some embodiments of the system, the optical setup is configured such that the sample and the FOE are positioned such that a first region on a first surface of the sample is in complete contact with a second surface of the FOE. The first region is defined by a portion of the sample including internal facets.

[0068] According to some implementations of the system, the sample is shaped as a thin plate or an elongated box.

[0069] According to some implementations of the system, the sample is a one-dimensional or two-dimensional reflective waveguide.

[0070] In some implementations of the system, the FOE is a prism. In some such implementations, the FOE is a triangular prism.

[0071] According to some embodiments of the system, the optical device also includes a slit or aperture-like optical mask and / or multiple shutters that can be translated, the optical mask and / or multiple shutters being configured to allow for the inspection of the internal facets one at a time.

[0072] According to some implementations of the system, the sensed data includes the measured intensity of the pixels that constitute a light spot on the image sensor. Each light spot is caused by a corresponding beam in a second plurality of light beams.

[0073] According to some implementations of the system, the system also includes a calculation module configured to calculate the parallelism deviation between the internal facets based on the sensed data.

[0074] According to some implementations of the system, as part of calculating parallelism deviation, the calculation module is configured to calculate the angular deviation (based on sensed data) between the beams in the second plurality of beams.

[0075] According to some implementations of the system, the calculation module is configured to calculate parameter ε. avg and / or ε max ε avg equal ε max Equal to max{ε ij} i，j＞ i or This is a set of two-dimensional vectors specifying the positions of the i-th and j-th light spots (formed by the beams in the second plurality of beams) on the image sensor or relative to the scale lines of the eyepiece. N is the number of internal facets. M is the number of distinct pairs of internal facets (i.e., M = N·(N-1) / 2). f is the focal length of the focusing lens or focusing lens assembly configured to focus the returning beam onto the image sensor.

[0076] According to some embodiments, the optical setup also includes a system configured to allow for the inspection of a translational slit or aperture optical mask and / or multiple shutters of the internal facets one at a time. The calculation module is configured to calculate the parallelism deviation between pairs of internal facets in two or more internal facets. According to some such embodiments, the pairs of internal facets comprise pairs of adjacent internal facets.

[0077] According to some implementations of the system, as part of calculating the parallelism deviation between pairs of internal facets, the calculation module is configured to calculate the grouped pitch deviation {ε} between the internal facets in each pair of internal facets. ij,p} i,j and / or roll deviation {ε ij,r} i,j Indices i and j involve distinct pairs of internal facets (within the paired internal facets). ε ij,p and ε ij,r These are the pitch and roll deviations between the i-th and j-th inner minor planes, respectively. According to some such implementations, these deviations are respectively transmitted via ε... ij,p =δ ij,p / (2n s )=(x i -x j ) / (2n s ·f) and ε ij,r =δ ij,r / (2n s )=(y i -y j ) / (2n s ·f) to calculate ε ij,p and ε ij,r δ ij,p δ is the pitch deviation between the i-th beam in the second plurality of beams caused by reflection from the i-th internal facet and the j-th beam in the second plurality of beams caused by reflection from the j-th internal facet. ij,r It is the roll deviation between the i-th beam and the j-th beam in the second plurality of beams. This is a set of two-dimensional vectors specifying the position of the spot on the image sensor caused by one of the second or more beams. The index k identifies the beam. N is the number of internal facets. f is the focal length of the focusing lens or focusing lens assembly configured to focus one of the second or more beams onto the image sensor.

[0078] According to some implementations of the system, the calculation module is configured to: as part of calculating the parallelism deviation between the internal facets, calculate the maximum pitch deviation (i.e., the range of pitch deviation) ε between the internal facets. max，p =(max{x i} i -min{x i} i ) / (2n s The maximum roll deviation (i.e., the range of roll deviation) ε between f) and / or the internal facets. max，r =(max{y i} i -min{y i} i ) / (2n s ·f). This is a set of two-dimensional vectors specifying the position (e.g., center point) of the spot caused by the second or more beams on the image sensor. The index i marks this point. N is the number of internal facets. f is the focal length of the focusing lens or focusing lens assembly configured to focus the second or more beams onto the image sensor.

[0079] According to some embodiments of the system, the optical device is configured to position the sample and / or FOE such that the second surface of the FOE is parallel to the first surface of the sample.

[0080] According to some embodiments of the system, the optical device is configured to position the sample and / or FOE such that a first region on a first surface of the sample is in complete contact with a second surface of the FOE. The first region is defined by a portion of the sample including an internal facet.

[0081] According to some implementations of the system, as part of calculating the parallelism deviation, the calculation module is configured to calculate the parallelism deviation between pairs of adjacent internal facets in two or more internal facets.

[0082] According to some implementations of the system, as part of calculating the parallelism deviation, the parallelism deviation of one of the two or more inner facets relative to a reference inner facet among the two or more inner facets is calculated.

[0083] According to some implementations of the system, the first surface of the FOE is coated with an anti-reflective coating.

[0084] According to some embodiments of the system, the optical device includes an autocollimator configured to generate a first plurality of light beams and focus a beam from a second plurality of light beams onto a photosensitive element.

[0085] According to some implementations of the system, the second plurality of beams includes beams that pass through the first surface of the sample and return from the sample via the FOE.

[0086] According to some embodiments of the system, the sample includes an external and flat second surface opposite to a first surface of the sample. Before exiting the sample via the first surface, the returning beam is reflected away from the second surface of the sample.

[0087] According to some embodiments of the system, the internal plane of the sample is orthogonal to the first surface of the sample. The second surface of the sample is parallel to the first surface of the sample.

[0088] According to some embodiments of the system, adjacent internal facets of the sample are spaced apart at regular intervals. A first tilt angle is equal to approximately (90° - arctan(2d1 / d2)). d1 is the distance between the first and second surfaces of the sample. d2 is the distance between adjacent internal facets of the sample.

[0089] According to some implementations of the system, the first tilt angle makes the ratio of the power of the second plurality of beams to the power of the first plurality of beams approximately maximum.

[0090] According to some embodiments of the system, the sample includes an external and flat second surface opposite to a first surface of the sample. The second plurality of light beams includes light beams emitted from the sample via the second surface of the sample.

[0091] According to some embodiments of the system, the system also includes a second optical element (SOE). The SOE has approximately equal to n s The refractive index is . The SOE includes an external and flat first surface and an external and flat second surface. The second surface of the SOE is opposite to the first surface of the SOE and is inclined at an acute second tilt angle relative to the first surface of the SOE. The optical device is additionally configured to enable the positioning of the sample and / or the SOE such that the second surface of the SOE is adjacent to the second surface of the sample. According to some such embodiments, the SOE has a refractive index equal to n. s refractive index

[0092] According to some embodiments of the system, the second plurality of beams includes beams that, after exiting the sample via a second surface of the sample, are transmitted into the SOE, and then exit the SOE via a first surface of the sample.

[0093] According to some embodiments of the system, the optical device is also configured to position the sample and / or SOE such that the second surface of the SOE is parallel to the second surface of the sample.

[0094] According to some embodiments of the system, the optical device is further configured to position the sample and / or SOE such that a first region on a first surface of the sample is in complete contact with a second surface of the FOE, and a second region of the sample is in complete contact with a second surface of the SOE. The first and second regions are defined by a portion of the sample including an internal facet. The second region is opposite to the first region.

[0095] According to some embodiments of the system, the second tilt angle is approximately equal to the first tilt angle, such that each of the second plurality of beams exits the SOE approximately perpendicular to the first surface of the SOE. According to some such embodiments, the second tilt angle is equal to the first tilt angle.

[0096] According to some embodiments of the system in which an internal facet of the sample is orthogonal to a first surface of the sample and a second surface of the sample is parallel to the first surface of the sample, adjacent internal facets of the sample are spaced apart at regular intervals. Each of the first and second tilt angles is equal to approximately (90° - arctan(d1 / d2)). d1 is the distance between the first and second surfaces of the sample. d2 is the distance between adjacent internal facets of the sample.

[0097] In some implementations of the system, the SOE is a prism. In some such implementations, the SOE is a triangular prism.

[0098] According to some implementations of the system, the first surface of the SOE is coated with an anti-reflective coating.

[0099] Some embodiments of this disclosure may include some, all, or none of the advantages described above. One or more other technical advantages may be readily apparent to those skilled in the art based on the accompanying drawings, description, and claims. Furthermore, while specific advantages have been listed above, various embodiments may include some, all, or none of the listed advantages.

[0100] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure pertains. In case of conflict, the patent specification including the definitions shall prevail. As used herein, unless the context clearly indicates otherwise, the indefinite articles “a” and “an” mean “at least one” or “one or more”.

[0101] Unless otherwise specifically stated, as will be apparent from the content of this disclosure, in some embodiments, terms such as “processing,” “computing,” “operation,” “determining,” “estimating,” “evaluating,” “measuring,” etc., may refer to the actions and / or processing of a computer or computing system or similar electronic computing device that manipulate and / or transform data represented as physical (e.g., electronic) quantities in computing system registers and / or memory into other data similarly represented as physical quantities in computing system memory, registers, or other such information storage, transmission, or display devices.

[0102] Embodiments of this disclosure may include means for performing the operations described herein. These means may be specifically constructed for a desired purpose, or may include a general-purpose computer selectively activated or reconfigured by a computer program stored in a computer. Such a computer program may be stored in a computer-readable storage medium, such as, but not limited to, any type of disk, including floppy disks, optical disks, CD-ROMs, magneto-optical disks, read-only memory (ROM), random access memory (RAM), electrically programmable read-only memory (EPROM), electrically erasable and programmable read-only memory (EEPROM), magnetic cards or optical cards, or any other type of medium suitable for storing electronic instructions and capable of being coupled to a computer system bus.

[0103] The processing and display described herein are not inherently associated with any particular computer or other device. Various general-purpose systems can be used with the programs taught herein, or it may prove convenient to construct more specialized devices to perform the desired methods. The desired structures of various such systems can be seen from the following description. Furthermore, embodiments of this disclosure are not described with reference to any particular programming language. It will be understood that the teachings of this disclosure as described herein can be implemented using various programming languages.

[0104] The various aspects of this disclosure can be described in the general context of computer-executable instructions, such as program modules, that are executed by a computer. Typically, program modules include routines, programs, objects, components, data structures, etc., which perform specific tasks or implement specific abstract data types. The disclosed implementations can also be practiced in a distributed computing environment, where tasks are performed by remote processing devices linked via a communication network. In a distributed computing environment, program modules can reside on both local computer storage media and remote computer storage media, including memory storage devices. Attached Figure Description

[0105] This document describes some embodiments of the present disclosure with reference to the accompanying drawings. This description, together with the drawings, makes it apparent to those skilled in the art how some embodiments can be practiced. The drawings are for illustrative purposes and do not attempt to show structural details of the embodiments in more detail than necessary for a basic understanding of the present disclosure. For clarity, some objects depicted in the drawings are not drawn to scale. Furthermore, two different objects in the same drawing may be drawn at different scales. In particular, in the same drawing, the scale of some objects may be greatly magnified compared to other objects.

[0106] In the attached diagram:

[0107] Figure 1A An optical-based system for measuring the internal facets of a sample, according to some embodiments, and a sample mounted on the system are schematically depicted.

[0108] Figure 1B It is based on some implementation methods Figure 1A An enlarged cross-sectional view of a portion of the sample;

[0109] Figure 1C It is based on some implementation methods Figure 1A A magnified perspective view of a portion of the sample;

[0110] Figure 1D The diagram schematically depicts the operation during sample inspection according to some embodiments. Figure 1A The system;

[0111] Figure 1E Provided according to some implementation methods Figure 1D A magnified view of a portion;

[0112] Figure 2A The illustration schematically depicts the results obtained as part of the inspection of a sample according to some embodiments. Figure 1A The light spot on the photosensitive surface of the system's image sensor;

[0113] Figure 2BThe illustration schematically depicts the results obtained as part of the inspection of a sample according to some embodiments. Figure 1A The light spot on the photosensitive surface of the system's image sensor;

[0114] Figure 3 An optical-based system for measuring the internal facets of a sample is schematically depicted, corresponding to... Figure 1A Specific implementation methods of the system;

[0115] Figure 4 The illustration schematically depicts the results obtained as part of the inspection of a sample according to some embodiments. Figure 3 The light spot on the photosensitive surface of the system's image sensor;

[0116] Figure 5 The diagram schematically depicts some components of an optical-based system on which the sample is mounted for measuring an internal facet of the sample. This optical-based system corresponds to... Figure 1A Specific implementations of the system; and

[0117] Figure 6A An optical-based system for measuring the internal facets of a sample, according to some embodiments, and a sample mounted on the system are schematically depicted.

[0118] Figure 6B It is based on some implementation methods Figure 6A An enlarged cross-sectional view of a portion of the sample;

[0119] Figure 7 An optical-based system for measuring the internal facets of a sample is schematically depicted, corresponding to... Figure 6A Specific implementation methods of the system;

[0120] Figure 8 A flowchart of an optical-based method for measuring the internal facets of a sample, according to some embodiments, is presented;

[0121] Figure 9 A flowchart is presented for an optical-based method for measuring the internal facets of a sample, which corresponds to... Figure 8 Specific implementations of the method; and

[0122] Figure 10 A flowchart is presented for an optical-based method for measuring the internal facets of a sample, which corresponds to... Figure 8 Specific implementations of the method. Detailed Implementation

[0123] The principles, uses, and implementation methods of the teachings herein can be better understood by referring to the accompanying specifications and figures. After carefully reading the descriptions and figures presented herein, those skilled in the art will be able to implement the teachings herein without excessive effort or experimentation. In the figures, the same reference numerals consistently denote the same parts.

[0124] In the specification and claims of this application, the words “comprising”, “having”, and their forms are not limited to members of the list that the words may be associated with.

[0125] As used herein, the term "about" can be used to specify a value of a parameter or argument (e.g., the length of an element) within a continuous range of values ​​near (and including) a given value. According to some embodiments, "about" can specify a parameter value between 80% and 120% of a given value. For example, stating "the length of the element is about 1 m" is equivalent to stating "the length of the element is between 0.8 m and 1.2 m." According to some embodiments, "about" can specify a parameter value between 90% and 110% of a given value. According to some embodiments, "about" can specify a parameter value between 95% and 105% of a given value. In particular, it should be understood that the terms "approximately equal to" and "equal to about" also cover exact equality.

[0126] As used herein, the terms “substantially” and “about” may be used interchangeably according to some implementations.

[0127] For ease of description, a three-dimensional Cartesian coordinate system is introduced in some of the accompanying drawings. Note that the orientation of the coordinate system relative to the depicted object can change from one drawing to another. Furthermore, the symbol ⊙ can be used to indicate an axis pointing "outside the page," while the symbol... It can be used to represent an axis pointing "inside the page".

[0128] In the accompanying drawings, optional elements and optional stages (in the flowchart) are depicted by dashed lines.

[0129] Throughout the description, vectors are represented by lowercase letters, typos, and bold (e.g., v).

[0130] The description includes quantitative relationships between parameters in the form of equations. Therefore, to make the description clearer, certain symbols are used throughout the description specifically to label particular types of parameters and / or parameters. The vector “u” (including superscripts and / or subscripts) represents a two-dimensional vector specifying the coordinates of a light spot (e.g., on an image sensor). The Greek letter “ε” (including superscripts and / or subscripts) represents an angle or the magnitude of an angle between planes. More specifically, the Greek letter “ε” is used to represent the parallelism deviation or the magnitude of parallelism misalignment between paired internal planes of a sample. The Greek letter “δ” (including superscripts and / or subscripts) represents an angle or the magnitude of an angle between two vectors. More specifically, the Greek letter “δ” is used to represent the angular deviation between the propagation directions of two beams. “n” s "" indicates the refractive index of the sample being examined using the disclosed system and / or method. "f" indicates the focal length of the focusing lens or lens assembly used to focus the returning beam onto a photosensitive element included in the disclosed system for examining the sample and / or used as part of the disclosed method for examining the sample. Therefore, the symbols u, ε, δ, n s The parameters ε, δ, and n in the context of an implementation should not be considered as being constrained by the specific implementation in which they are first introduced in the text. Specifically, the parameters ε, δ, and n in the context of an implementation should be considered as specific to the implementation. s The description of the values, ranges and / or constraints on the values ​​of f (and parameters μ, σ and Δ) and u (components) does not necessarily continue in another implementation.

[0131] Throughout the specification, the internal flat surfaces of a three-dimensional element (such as the flat boundary between two parts of a three-dimensional element or the internal flat material layer incorporated into a three-dimensional element) are referred to as "internal facets".

[0132] As used in this article, when an object is designed and manufactured to represent a property, the object may be said to represent that property (i.e., characterized by it), such as the angle of inclination between the flat surfaces of a sample. However, in reality, the property may not be perfectly represented due to manufacturing tolerances.

[0133] system

[0134] According to one aspect of some embodiments, an optical-based system is provided for measuring a sample (e.g., a one-dimensional or two-dimensional reflective waveguide), the sample comprising a substrate (constituting the body of the sample) characterized by a uniform refractive index and two or more internal facets embedded in the substrate and nominally parallel, and at least approximately orthogonal to the outer (first) surface of the sample (e.g., the main surface of the reflective waveguide). This system can be used to achieve… Figure 8An optical-based method (used to verify the parallelism between internal facets of a sample).

[0135] The system includes at least one optical element (e.g., a prism) and an optical device comprising a light source, a light-sensing component, and optional optical apparatus. The optical apparatus includes at least a collimating lens or collimating lens assembly configured to collimate the light generated by the light source, thereby preparing a first plurality of light beams.

[0136] The optical element has a refractive index approximately equal to that of the substrate and includes an external, flat first surface and an external, flat second surface opposite to the first surface. The second surface of the optical element is inclined at an acute (first) angle relative to the first surface of the optical element. The optical device is configured such that a sample and / or the optical element can be positioned such that (i) the second surface of the optical element is adjacent to the first surface of the sample, and (ii) when positioned in this manner (i.e., when the second surface of the positioned optical element is adjacent to the first surface of the sample), a first plurality of light beams generated by a light source will illuminate the first surface of the optical element approximately perpendicular to it.

[0137] The optical device may include a focusing lens or focusing lens assembly configured to focus a second plurality of light beams onto a photosensitive element to allow measurement of angular deviations between the beams in the second plurality of light beams. The second plurality of light beams comprises beams from a first plurality of light beams that pass through (i.e., via) the optical element, are transmitted into the sample, and are reflected off the sample after exiting an internal facet once. Based on the (measured) angular deviations between the beams in the second plurality of light beams, parallelism deviations between the internal facets can be calculated.

[0138] According to some implementation methods, such as the following: Figures 1A to 5 In the embodiment described in the description, after being reflected away from the inner facet, the reflected beam is reflected away from the second surface of the sample, which is opposite to the first surface of the sample. These double-reflected (i.e., reflected twice within the sample) beams are transmitted out of the sample and enter the optical element via the first surface of the sample and the second surface of the optical element, and exit the optical element via the first surface of the optical element (e.g., refracted out) (thus obtaining a second plurality of beams).

[0139] According to some implementation methods, such as the following: Figures 6A to 7The embodiment described in the description includes a second optical element (SOE) that may be similar to a first optical element (FOE). The SOE has a refractive index approximately equal to that of the substrate and includes an external, flat first surface and an external, flat second surface. The second surface of the SOE is inclined at an acute second angle relative to the first surface of the SOE. The optical device is additionally configured to position the sample and / or the SOE such that the second surface of the SOE is adjacent to the second surface of the sample. After reflection away from the inner facet, the reflected light beam (i) is transmitted from the sample and enters the second optical element via the second surface of the sample opposite to the first surface of the sample and the second surface of the SOE, and (ii) exits from the SOE via the first surface of the SOE (e.g., refracted) (thus obtaining a second plurality of light beams).

[0140] According to some implementations in which the second surface of the sample is parallel to the first surface of the sample (e.g., when the first and second surfaces of the sample are the main surfaces of the reflecting waveguide), the second tilt angle can be approximately equal to the first tilt angle, thereby ensuring that the beams in the second plurality of beams exit the SOE approximately perpendicular to the first surface of the SOE (which can help reduce dispersion).

[0141] Figure 1A An optical-based system 100 for measuring internal facets in a sample, according to some embodiments, is schematically depicted. The optical-based system 100 is configured to verify the parallelism between internal facets of a sample. More specifically, Figure 1A A cross-sectional side view of system 100 and sample 10 according to some embodiments is presented. (It should be understood that sample 10 does not constitute part of system 100.)

[0142] Sample 10 includes a light-transmitting substrate 12 and two or more internal facets 14 embedded in the substrate 12. Sample 10 also includes an external first surface 16a (also referred to as the "sample first surface") and an external second surface 16b (also referred to as the "sample second surface"). The sample second surface 16b is opposite to the sample first surface 16a. Each of the sample first surface 16a and the sample second surface 16b may be planar. According to some embodiments, and as... Figures 1A to 1EAs depicted, the second surface 16b of the sample is parallel to the first surface 16a of the sample. According to some embodiments, each internal facet 14 constitutes a thin semi-reflective or reflective layer embedded in the substrate 12. According to some embodiments, one or more internal facets 14 may be a thin film or a partial mirror. According to some embodiments, one or more internal facets 14 may be composed of or comprise glass and / or dielectric materials. According to some embodiments, the substrate 12 may be a one-dimensional or two-dimensional reflective waveguide (also referred to as a "geometric waveguide"). According to some such embodiments, the first surface 16a and the second surface 16b of the sample constitute the main surfaces of the waveguide. According to some embodiments, the substrate 12 may be made of glass, crystal, or a transparent polymer.

[0143] The sample portion 18 of sample 10 corresponds to the portion (e.g., a segment) where the internal facet 14 of substrate 12 is located (while the portion of sample 10 complementary to sample portion 18 may not have any internal facet 14). See also... Figure 1B and Figure 1C , Figure 1B Enlarged views of sample portion 18 according to some embodiments are provided. These are provided as non-limiting examples, intended to facilitate description by making them more concrete. Figure 1A and Figure 1B In the diagram, the inner facet 14 is shown as comprising three inner facets: a first inner facet 14a, a second inner facet 14b, and a third inner facet 14c, wherein the second inner facet 14b is disposed between the first inner facet 14a and the third inner facet 14c. Those skilled in the art will readily recognize that the case of three inner facets encompasses the nature of any number of inner facets (e.g., 4, 5, 10, or more). Figure 1C A perspective view of the end 15 of a sample portion 18 including a first inner facet 14a and a second inner facet 14b, according to some embodiments, is provided.

[0144] The internal facets 14 are nominally parallel. That is, according to the intended design of sample 10, the internal facets 14 are parallel. In reality, due to manufacturing defects, the internal facets 14 may not typically exhibit perfect parallelism. According to some embodiments, each internal facet 14 is positioned at a nominal angle μ relative to the first surface 16a of the sample at approximately 90°. nom (Across a plane parallel to the zx plane) nominally inclined. According to some such embodiments, and as... Figures 1A to 1E As depicted, the internal facet 14 is nominally orthogonal to the first sample surface 16a (and, in the embodiment where the second sample surface 16b is parallel to the first sample surface 16a), i.e., μ nom=90°. In practice, each internal facet 14 can be oriented at its own actual angle, which is equal to the nominal angle μ. nom Slightly different. The first internal plane 14a, the second internal plane 14b, and the third internal plane 14c are oriented relative to the first surface 16a of the sample at a first angle μ1, a second angle μ2, and a third angle μ3, respectively.

[0145] It should be noted that due to manufacturing defects, the actual angle μ i (i = 1, 2, 3) may be each other and / or with the nominal angle μ nom They differ not only in magnitude but also in the corresponding containment plane. For example, considering μ nom If μ1 is contained in a first plane parallel to the zx plane, then μ1 can be contained in a second plane inclined relative to that first plane. Similarly, μ2 can be contained in a third plane inclined relative to the first plane and / or the second plane. In other words, using a, b, and c respectively (in... Figure 1C The diagram shows that a and b) represent unit vectors perpendicular to the first inner plane 14a, the second inner plane 14b, and the third inner plane 14c. Most generally, a ≠ b, b ≠ c, and c ≠ a.

[0146] As used in this article, "pitch of the internal facet" refers to the angle of rotation of the internal facet about the y-axis relative to its nominal orientation. "Roll of the internal facet" refers to the angle of rotation of the internal facet about the x-axis relative to its nominal orientation.

[0147] The nominal orientation of the internal facet 14 is in Figure 1C The value is indicated by the unit vector q (i.e., a = b = c = q in the absence of manufacturing defects). According to... Figure 1C The coordinate system is chosen such that q points along the direction defined by the z-axis. The first plane 17a (depicted by dashed lines) indicates the nominal location of the first inner plane 14a. The coordinates indicated on the first plane 17a are a... a x and a y The first inner plane 14a is shown as differing from the first plane 17a in both pitch and roll, as represented by the non-zero x and y components of a (i.e., a). x and a y The second plane 17b (described by dashed lines) indicates the nominal location of the second inner plane 14b. The plane 17b indicates the positions of b... b x and b yThe second inner plane 14b is shown as differing from the second plane 17b in both pitch and roll, as indicated by the non-zero x and y components of b (i.e., b...). x and b y The first inner plane 14a and the second inner plane 14b are shown as differing from each other in both pitch and roll (i.e., in...). Figure 1C In the middle, b x >a x And b y >a y ).

[0148] Each of the first sample surface 16a and the second sample surface 16b extends from the first end 11a of the sample 10 to the second end 11b. The sample portion 18 defines a region 13 on the first sample surface 16a that is positioned above the (all) internal facets 14.

[0149] According to some embodiments, system 100 includes a light-transmitting optical element 102 and an optical device 104. System 100 may also include a controller 108 functionally associated with and configured to control the operation of the optical device 104. According to some embodiments, and as... Figure 1A The depicted optical device 104 includes an illumination and collection assembly (ICA) 112 and a holding base structure 114 for mounting a sample 10 thereon. According to some embodiments, and as described in detail below, the holding base structure 114 may include an orientation base structure configured to allow controllable setting of the orientation of the sample 10. The ICA 112 includes a light source 122 (or multiple light sources) and a light sensing element 124. According to some embodiments, the light sensing element 124 may include an image sensor. According to some embodiments, the image sensor may be a CCD sensor or a CMOS sensor. According to some embodiments, the light sensing element 124 may be a camera device. Alternatively, according to some embodiments, the light sensing element 124 may be an eyepiece assembly configured to visually determine (i.e., by eye) the deviation between light rays focused onto the eyepiece assembly. According to some embodiments, the ICA 112 may also include an optical device 128, the function of which is described below.

[0150] Optical element 102 includes a substrate 132, which forms the body of optical element 102 and has a refractive index (e.g., greater than n) that is approximately the same as that of substrate 12 of sample 10. s -0.02 and less than n sThe substrate 132 is made of a material having a refractive index of +0.02. According to some embodiments, the substrate 132 is made of a material having the same refractive index as the substrate 12. The optical element 102 also includes an outer first surface 134a (e.g., the outer first surface of the substrate 132) and an opposite outer second surface 134b (e.g., the outer second surface of the substrate 132). According to some embodiments, and as... Figure 1A As depicted, the first surface 134a of the optical element is flat. According to some such embodiments, and as... Figure 1A As depicted, the second surface 134b of the optical element is also flat and inclined relative to the first surface 134a of the optical element. According to some embodiments, the optical element 102 is a prism. According to some such embodiments, the prism may be a triangular prism.

[0151] According to some embodiments, particularly in which (i) the first sample surface 16a and the second sample surface 16b are parallel, (ii) the inner facet 14 is nominally orthogonal to each of the first sample surface 16a and the second sample surface 16b, and (iii) adjacent inner facets are spaced apart at regular intervals, the second optical element surface 134b may be tilted relative to the first optical element surface 134a at an angle σ, which is parallel to the zx plane and equal to (90° - arctan(2d1 / d2)), that is, the angle σ is equal to 90 degrees minus arctan(2d1 / d2). Here, d1 is the distance between the first sample surface 16a and the second sample surface 16b, and s2 is the distance between adjacent inner facets (e.g., inner facets 14a and 14b, inner facets 14b and 14c). Distances d1 and d2 are determined by... Figure 1B The double-headed dashed arrow indicates this. Below is... Figure 1D and Figure 1E The description explains the reason for the above tilt angle selection. The ICA 112 is configured to output a collimated beam (such as...). Figure 1C and Figure 1D As shown, the collimated beam is generated by a light source 122 and optionally manipulated (e.g., collimated) by an optical device 128. According to some embodiments, the optical device 128 may include a collimating lens or a collimating lens assembly (not shown). The relative orientation of the optical element 102 and the ICA 112 (more precisely, the illumination component of the ICA 112) can be configured such that the beam output from the ICA 112 illuminates the first surface 134a of the optical element perpendicularly or at least approximately perpendicularly (e.g., within 1°, 1.5°, or even 2° of perpendicular incidence) onto the first surface 134a of the optical element.

[0152] Optical element 102 and optical device 104 can be configured to ensure that the incident beam is reflected at most negligibly away from the first surface 134a of the optical element, or to ensure that any portion directly reflected from the first surface 134a of the optical element is distinguishable from the returning beam caused by transmission into the optical element 102 and sample 10, reflection away from the internal facet 14, and re-passing through the optical element 102. As follows... Figure 1C and Figure 1D As described in the description, the parallelism deviation between the internal facets 14 is calculated based on the sensing data of the returned beam (i.e., by measuring one or more parameters characterizing each returned beam). According to some embodiments, the incident beam exiting from the first surface 134a of the optical element with negligible reflection can be achieved by coating the first surface 134a of the optical element with an anti-reflective coating (if it has not already been coated). The coating can be permanent or temporary.

[0153] In order not to hinder Figure 1D and Figure 1E The light beam reflected off the first surface 134a of the optical element is not shown.

[0154] Alternatively, according to some embodiments, the incident beam may be slightly tilted by an angle Δ relative to the normal of the first surface 134a of the optical element to ensure that the propagation direction of the light directly reflected from the first surface 134a of the optical element is sufficiently different from the propagation direction of each of the returning beams (when exiting the optical element 102 after reflection from the inner facet 14). In such embodiments, the incident beam may be selected to be monochromatic to minimize dispersion transmitted into the optical element 102. According to some embodiments, 0.3° ≤ |Δ| ≤ 0.5°, 0.2° ≤ |Δ| ≤ 0.7°, or even 0.1° ≤ |Δ| ≤ 1°. Each possibility corresponds to a different embodiment.

[0155] According to some embodiments, the light source 122 can be configured to generate a monochromatic beam (such that the beam output by the ICA 112 is monochromatic). According to some embodiments, the light source 122 can be a laser source (and the beam output by the ICA 112 is a laser beam). According to some embodiments where the light source 122 is a laser source, the ICA 112 can be configured to output a collimated extended laser beam. According to some such embodiments, the optical device 128 may include a beam expander (not shown) configured to increase the diameter of the laser beam. According to some embodiments, such as where the sample 10 is a one-dimensional waveguide, the diameter of the extended laser beam (e.g., the maximum diameter when the cross-section of the extended laser beam defines an ellipse) can be approximately equal to the longitudinal dimension of region 13. According to some embodiments, such as where the sample 10 is a two-dimensional waveguide, the cross-sectional area of ​​the extended laser beam can be approximately equal to the size of the cross-sectional area of ​​region 13.

[0156] Note that in embodiments where the first surface 134a of the optical element is coated with an anti-reflective coating, a multi-color incident beam can be used, as long as the incident beam is projected perpendicularly onto the first surface 134a of the optical element (thereby preventing dispersion or at least significantly reducing dispersion).

[0157] According to some embodiments, the light source 122, the photosensing component 124, and at least some optical devices 128 can constitute an autocollimator or components constituting an autocollimator. According to some embodiments, the autocollimator is a digital autocollimator or an electronic autocollimator. According to some embodiments, the autocollimator is a laser autocollimator. According to some embodiments, the autocollimator is a visual autocollimator.

[0158] According to some embodiments, the optical device 128 may also include a translationally slit or apertureed optical mask (not shown; for example, the translationally slit optical mask of FIG2), such an optical mask being configured to control the incident position of a light beam (e.g., a laser beam) on the first surface 134a of the optical element, thereby allowing each internal facet 14 to be inspected individually. Alternatively, according to some embodiments, the optical device 128 may also include a plurality of shutters, such a plurality of shutters being configured to allow (enable) individual inspection of each internal facet 14.

[0159] According to some embodiments, the retaining base structure 114 can be configured to allow controllable setting of the orientation between the sample 10 and the optical element 102. Specifically, the retaining base structure 114 can be configured to allow orientation of the sample 10 and / or the optical element 102 such that the first surface 16a of the sample is adjacent to and parallel to the second surface 134b of the optical element. According to some embodiments, the retaining base structure 114 can also be configured to orient the sample 102 such that the incident beam output from the ICA 112 will vertically (i.e., orthogonally) illuminate the first surface 134a of the optical element. As a non-limiting example, according to some embodiments, the retaining base structure 114 may include an orientable stage assembly 138 or an orientable stage (e.g., a biaxial stage).

[0160] The stage assembly 138 is configured to allow mounting of a sample, such as sample 10, and adjustment of the sample's pitch and / or roll angles. According to some embodiments, the stage assembly 138 may be configured to allow manipulation of the sample mounted thereon in each of the six degrees of freedom. According to some embodiments, the stage assembly 138 may include two goniometers (e.g., Figure 5 The goniometer depicted in the image; Figure 1A (Not shown): A pitch goniometer and a roll goniometer, one mounted on top of the other. According to some such embodiments, the stage assembly 138 may include a platform (e.g., Figure 5 The inclined platform depicted in the image; Figure 1A (Not shown in the image), the platform is configured to (i) be positioned on top of one of the two goniometers and (ii) place the sample 10 thereon. In some such embodiments, the optical element 102 may be positioned on and supported by the sample 10. Alternatively, according to some embodiments, the holding base 114 may include an oriented holding gear (not shown) configured to hold and controllably orient the optical element 102. According to some embodiments, the holding base 114 may be functionally associated with and configured to be controlled by the controller 108.

[0161] Also refer to Figure 1D and Figure 1E , Figure 1D A cross-sectional side view of a system 100 and a sample 10 according to some embodiments is presented, wherein the sample 10 is subjected to an inspection performed by the system 100. Figure 1E Provided by the dashed line L Figure 1D A magnified view of a portion. In operation, according to some embodiments, an extended and collimated incident beam, indicated by arrow 105, is projected onto the first surface 134a of the optical element (not all extended and collimated incident beams are numbered). According to some embodiments, particularly those in which the first surface 134a of the optical element is coated with an anti-reflective coating, the incident beam can be projected perpendicularly onto the first surface 134a of the optical element.

[0162] An incident light beam (or at least a portion thereof) is transmitted through the first surface 134a of the optical element into the optical element 102, thereby obtaining a transmitted light beam. The transmitted light beam is indicated by arrow 115 (not all transmitted light beams are numbered). The transmitted light beam travels through the optical element 102, passes through (i.e., through) the second surface 134b of the optical element and the first surface 16a of the sample into the sample 10, and propagates toward the inner facet 14. The transmitted light beam is reflected from the inner facet 14 toward the second surface 16b of the sample.

[0163] More specifically, since the internal facets 14 may differ slightly from each other in their respective orientations, the transmitted beam can be reflected away from each internal facet 14 at slightly different angles. Therefore, multiple reflected beams can be obtained, each slightly different in its propagation direction. The first reflected beam—corresponding to the portion of the transmitted beam reflected away from the first internal facet 14a—is indicated by arrow 125a. The second reflected beam—corresponding to the portion of the transmitted beam reflected away from the second internal facet 14b—is indicated by arrow 125b. The third reflected beam—corresponding to the portion of the transmitted beam reflected away from the third internal facet 14c—is indicated by arrow 125c.

[0164] As indicated by arrows 135a, 135b, and 135c, the reflected beam (again) exits the sample 10 via the sample 10 through the sample 10's first surface 16a and re-enters (i.e., is transmitted into) the optical element 102 via the optical element's second surface 134b. After re-entering the optical element 102, the double-reflected (i.e., reflected twice within the sample 10) beam travels to the optical element's first surface 134a and exits (e.g., is refracted) from the optical element 102, thus obtaining multiple returning beams. The first returning beam caused by the refraction of the first double-reflected beam (indicated by arrow 135a) from the optical element 102 is indicated by arrow 145a. The second returning beam caused by the refraction of the second double-reflected beam (indicated by arrow 135b) from the optical element 102 is indicated by arrow 145b. The third returning beam caused by the refraction of the third double-reflected beam (indicated by arrow 135c) from the optical element 102 is indicated by arrow 145c. The returning beam propagates toward ICA 112 and is focused onto the photosensing component 124 by the optical device 128.

[0165] The light sensing element 124 is configured to allow the angular deviation between pairs of returning beams focused thereon to be obtained from its sensing data (i.e., measurement data of the returning beams obtained by the light sensing element 124 or using the light sensing element 124). For example, as follows: Figure 2A and Figure 2B As described in the description, the magnitude of the parallelism deviation between the internal facets 14 can be inferred from the angular deviation.

[0166] According to some implementations, the tilt angle σ is equal to (90° - arctan(2d1 / d2)). (By reading...) Figure 1D and Figure 1E Clearly, the above selection of σ ensures that each ray in the reflected beam (or at least a portion thereof) is transmitted back into the optical element 102 after being reflected away from the second surface 16b of the sample without being reflected again by any of the internal facets 14. Therefore, the above selection of σ reduces losses, thereby improving the detection of the returning beam (e.g., by ensuring that the returning beam forms a bright spot on the photosensitive surface of the image sensor). According to some embodiments, the tilt angle σ is equal to approximately (90° - arctan(2d1 / d2)).

[0167] In some embodiments where the first surface 134a of the optical element is not coated with an anti-reflective coating, light projected onto the first surface 134a of the optical element will have a second portion reflected, in addition to its first portion being transmitted into the optical element 102. In such embodiments, to ensure that the returned beam (i.e., the beam returning through the optical element 102 after being reflected away from the inner facet 14) is distinguishable from the portion of the incident beam reflected from the first surface 134a of the optical element, the incident beam can be projected at a small (non-zero) angle of incidence (relative to the first surface 134a of the optical element). Therefore, as Figure 2B In the embodiments described in the present invention and detailed below, in which the light sensing component 124 is an image sensor, the light spots formed by the returned light beam typically cluster (i.e., concentrate), while the light spots formed by the direct reflection portion of the incident light beam fall clearly outside the cluster.

[0168] According to some implementation methods, and as Figure 1A , Figure 1D and Figure 1E As depicted, optical element 102 can be positioned on (and optionally supported by) sample 10 such that the second surface 134b of the optical element contacts the entire first surface 16a of the sample, or at least the entire region 13. In such an embodiment, the transmitted light beam enters the sample 10 directly from optical element 102, while the reflected light beam enters the optical element 102 directly from sample 10.

[0169] According to some embodiments, the second surface 134b of the optical element does not contact the first surface 16a of the sample. If the incident beam is not monochromatic, the space between the optical element 102 and the sample 10 (unless filled as described below) may cause dispersion as the transmitted beam exits the optical element 102 via the second surface 134b. In embodiments where the second surface 134b of the optical element is parallel to and sufficiently polished with respect to the first surface 16a of the sample (and the refractive index of the optical element 102 is equal to the refractive index of the substrate 12), beams of different frequencies will be realigned upon entering the sample 10. Otherwise, to avoid or at least mitigate dispersion, according to some embodiments, the light source 122 may be configured to generate a monochromatic beam (e.g., a laser beam), and / or a shape-moldable interface (not shown) with a refractive index matching may be inserted between the sample 10 and the optical element 102 (to be confined between the first surface 16a of the sample and the second surface 134b of the optical element). The shape-moldable interface may have approximately the same refractive index as the sample 10 (e.g., greater than n). s -0.02 and less than n s+0.02). The shape-plastic interface can be a paste, liquid, or gel characterized by surface tension and / or adhesive properties, so as to maintain its integrity and arrangement when confined in a narrow space. According to some embodiments, the shape-plastic interface can be a stretchable material. Therefore, the light beam propagating through the optical element 102, the shape-plastic interface, and the sample 10 will substantially maintain its propagation direction as it enters the shape-plastic interface from the optical element 102 and from the shape-plastic interface into the sample 10.

[0170] According to some embodiments, a shape-moldable interface (as described above) can also be used to prevent total internal reflection of the double-reflected beam (i.e., in embodiments where the tilt angle σ allows the double-reflected beam to irradiate the first surface 134a of the optical element at an angle of incidence greater than the critical angle defined by the substrate 12 and the air).

[0171] Also refer to Figure 2A , Figure 2A A light spot 201 on the photosensitive surface 244 of an image sensor 224 according to some embodiments of system 100 is schematically depicted, wherein (i) the first surface 134a of the optical element is coated with an anti-reflective coating, and (ii) the ICA 112 includes an autocollimator. The autocollimator includes the image sensor 224, which corresponds to or is included in a specific embodiment of the photosensing component 124. According to some embodiments, the light spot 201 includes: a first light spot 201′, a second light spot 201″, and a third light spot 201″′. The light spot 201 is formed by a returned beam (in... Figure 1D and Figure 1E (Indicated by arrow 145). According to some implementations, the spot may not be attributable to a specific returning beam. (Unless each internal facet is examined individually, for example, as shown below). Figure 3 and Figure 4As described in the description, or alternatively, if additional information uniquely characterizing each internal facet is available, for example, if the internal facets differ from each other by design in terms of their reflectivity. In particular, it should be understood that the first spot 201' can be formed by a first returning beam (caused by reflection from the first internal facet 14a), a second returning beam (caused by reflection from the second internal facet 14b), or a third returning beam (caused by reflection from the third internal facet 14c). Similarly, the second spot 201″ can be formed by any of the returning beams (but a different returning beam from the one that formed the first spot 201'), and the third spot 201″′ can be formed by any of the returning beams (but a different returning beam from each of the returning beams that formed the first spot 201' and the second spot 201″). However, as described below by way of example, information such as the average parallelism deviation (also known as the average “radial deviation”) and the maximum parallelism deviation (also known as the maximum “radial deviation”) can be extracted from the coordinates of the spot 201. As used herein, the “parallelism radial deviation” between the inner facets generally refers to a quantized deviation of the parallelism deviation that takes into account both pitch and roll deviations.

[0172] Two-dimensional vector u α =(u α,x ,u α,y ), u β =(u β,x ,u β,y ) and u γ =(u γ,x ,u γ,y The positions of the first light spot 201′, the second light spot 201″, and the third light spot 201″′ are specified respectively. Note that the light spot 201 is spatially extended (i.e., not one-dimensional), and according to some implementations, the vector u α u β and u γ The center points (coordinates) of the first spot 201', the second spot 201" and the third spot 201"′ can be specified separately. According to some implementations, the center point can be calculated by averaging the coordinates of each pixel that constitutes the intensity-weighted spot.

[0173] Unit vector p α This corresponds to the propagation direction of the returning beam that generates the first light spot 201'. Unit vector p β This corresponds to the propagation direction of the returning beam that generates the second spot 201″. Unit vector p γ This corresponds to the propagation direction of the returning beam that generates the third spot 201″′. Angular deviation δ γβ Corresponding to p γ With pβ The magnitude of the angle between them. Angular deviation δ αγ Corresponding to p α With p γ The magnitude of the angle between them. Angular deviation δ βα Corresponding to p β With p α The magnitude of the angle between them. Angular deviation δ γβ δ αγ and δ βα According to vector u α u β and u γ From this, it can be deduced that... Then, based on the angular deviation, the parallelism deviation (the magnitude) between the internal small planes can be deduced.

[0174] Assumption Figure 2A The coordinate system depicted in the figure has possible translations through the origin and Figure 1D The coordinate system depicted is consistent. According to some embodiments where a focusing lens (not shown; for example, the focusing lens of an autocollimator) with a focal length of f1 is used to focus the returning beam onto an image sensor (e.g., the image sensor of an autocollimator), the relation can be used. and To calculate the magnitude of the angular deviation between the returned beams.

[0175] Unit vector q α The normal to the inner plane from which the beam that generates the first spot 201' is reflected. (Therefore, most generally, the unit vector q) α (This can correspond to the normals of the first inner facet 14a, the second inner facet 14b, or the third inner facet 14c). Unit vector q β The normal to the inner plane from which the beam that generates the second spot 201″ is reflected. Unit vector q γ The normal to the inner plane from which the beam that produces the third spot 201″′ is reflected. Deviation ε γβ Corresponding to q β With q γ The magnitude of the angle between them. Deviation ε αγ Corresponding to q α With q γ The magnitude of the angle between them. Deviation ε βα Corresponding to q β With q α The magnitude of the angle between them. This will be obvious to a technician (according to Snell's law), n s ·sin(2ε γβ )=sin(δ γβ ), ns ·sin(2 αγ )=sin(δ αγ ), and n s ·sin(2ε βα )=sin(δ βα ).

[0176] The expression max{ε γβ ,ε αγ ,ε βα} can be used to quantify the maximum radial deviation of parallelism. The expression (ε) γβ +ε αγ +ε βα ) / 3 can be used to quantify the average radial deviation of parallelism between the inner facets. Since no spot 201 is typically attributable solely to reflections departing from a particular inner facet, the above expression is independent of the sign of the angular deviation.

[0177] Similarly (through the choice of the depicted coordinate system), the magnitude of the pitch deviation between the interior planes (i.e., ε) γβ,p ε αγ,p and ε βα,p ) can be determined according to the relation tan(δ) γβ,p )=|u β,x -u γ,x | / f and n s ·sin(2ε γβ,p )=sin(δ γβ,p ),tan(δ αγ,p )=|u γ,x -u α,x | / f and n s ·sin(2ε αγ,p )=sin(δ αγ,p ), and tan(δ) βα,p )=|u α,x -u β,x | / f and n s ·sin(2ε βα,p )=sin(δ βα,p ) can be calculated using the relation tan(δ). γβ,r )=|u β,y -u γ,y | / f and n s ·sin(2ε γβ,r )=sin(δ γβ,r ), tan(δ) αγ,r )=|u γ,y -u α,y | / f and n s ·sin(2ε αγ,r )=sin(δαγ,r ) and tan(δ βα,r )=|u α,y -u β,y | / f and n s ·sin(2ε βα,r )=sin(δ βα,r This is used to calculate the magnitude of the roll deviation between the internal facets (i.e., ε). γβ,r ε αγ,r ε βα,r ). δ γβ,p and δ γβ,r Corresponding to p respectively γ With p β The values ​​of pitch and roll between. δ αγ,p and δ αγ,r Corresponding to p respectively α With p γ The values ​​of pitch and roll between. δ βα,p and δ βα,r Corresponding to p respectively β With p α The values ​​of pitch and roll between. The expression max{ε γβ,p ,ε αγ,p ,ε βα,p} and max{ε γβ,r ,ε αγ,r ,ε βα,r} can be used to quantify the maximum pitch and roll deviations between the internal facets 14. The expression (ε) γβ,p +ε αγ,p +ε βα,p ) / 3 and (ε γβ,r +ε αγ,r +ε βα,r ) / 3 can be used to quantify the average deviation (value) of pitch and roll between the internal small planes 14.

[0178] Alternatively, according to some implementation methods, a relational expression can be used. and n s ·sin(2ε max )=sin(δ max To quantify the maximum parallelism deviation ε between the internal facets 14 max .

[0179] Based on some implementations where the parallelism deviation is sufficiently small, a small-angle approximation can be used. In the case of a small-angle approximation (when processed in radians), and Similarly, ε γβ,p =|u β,x -u γ,x| / (2n s ·f1), ε αγ,p =|u γ,x -u α,x | / (2n s ·f1) and ε βα,p =|u α,x -u β,x | / (2n s ·f1) and ε γβ,r =|u β,y -u γ,y | / (2n s ·f1)ε αγ,r =|u γ,y -u α,y | / (2n s ·f1) and ε βα,r =|u α,y -u β,y | / (2n s ·f1).

[0180] Also refer to Figure 2B , Figure 2B A light spot 221 and a light spot 231 on a photosensitive surface 244 according to some embodiments of system 100 are schematically depicted, wherein the incident light beam is projected at a slight angle relative to the normal of the first surface 134a of the optical element and the first surface 134a of the optical element is not coated with an anti-reflective coating (and ICA 112 includes an autocollimator with an image sensor). The light spot 231 is formed by a portion of the incident light beam that is directly reflected away from the first surface 134a of the optical element (i.e., this portion of the incident light beam is specularly reflected from the first surface 134a of the optical element).

[0181] Two-dimensional vector v = (v x ,v y Specify the coordinates of spot 231 (e.g., the coordinates of the center point of the spot). Two-dimensional vector u′=(u x ′,u y ′), u″=(u x ",u y ″) and u″′=(u x "′,u yThe coordinates of spot 221 are specified by ″′, which includes a first spot 221′, a second spot 221″, and a third spot 221″′ formed by the beam returning from the inner facet 214. The first spot 221′ is the spot closest to spot 231 among the spots 221. d represents the distance between the first spot 221′ and spot 231 (i.e., d = |u′-v|). According to some embodiments, the incident angle of the incident beam on the first surface 134a of the optical element (the angle at which the incident beam is tilted relative to the normal of the first surface 134a of the optical element) can be selected to ensure that d will be much larger than each of |u′-v|, |u″-v|, and |u″′-v|, thereby making it possible to identify spot 231 (i.e., the portion of spot 231 that leaves the first surface 134a of the optical element due to the direct reflection of the incident beam).

[0182] According to some embodiments, controller 108 may be communicatively associated with computing module 146. Computing module 146 may include one or more processors and volatile and / or non-volatile memory components. One or more processors may be configured to receive raw or processed sensing data (i.e., measurement data obtained by the light sensing component 124) from controller 108 and, based on the sensing data, calculate the overall (e.g., average or maximum) deviation of parallelism and / or the parallelism deviation between pairs of internal facets 14. Raw sensing data may include the intensity of pixels constituting the spot formed by the returning beam focused on the light sensing component 124. Processed sensing data may include the angular deviation between (pairs of) returning beams or the center point (e.g., vector u) of the spot formed by the returning beams. α u β and u γ (or the coordinates of vectors u′, u″, and u″′). According to some such implementations, the calculation module 146 may be configured to process the raw sensing data of the light sensing component 124 to obtain the angular deviation between (pairs of) the returning beams.

[0183] According to some embodiments, one or more processors may include a graphics processing unit (GPU) configured to execute image recognition software to identify light spot 201 (or light spots 221 and 231). According to some embodiments, for example, in which the first surface 134a of the optical element is not coated with a reflective coating, the image recognition software may also be configured to distinguish light spots (e.g., light spot 231) formed by light beams directly reflected off the first surface 134a of the optical element from light spots (e.g., light spot 221) formed by returning light beams that have undergone reflection from the inner facet 14.

[0184] According to some implementations, the computing module 146 may be included in the system 100.

[0185] According to some alternative embodiments not depicted in the figures, instead of optical device 104, system 100 may include an interferometric measuring device and may extract information from the interference pattern formed by the returning beam, including the radial deviation of parallelism between pairs of internal facets 14. According to some such embodiments, the interferometric measuring device may include a beam splitter array and an associated array of controllably opening and closing blocking filters configured to allow examination of pairs of internal facets one at a time. More specifically, the beam splitter and blocking filter array may be configured to (i) split the incident beam into a selectable pair of incident sub-beams normally incident on optical element 102, and (ii) recombine the two returning sub-beams, respectively, caused by this pair of incident beams, into a single combined returning beam, which is then sensed by an image sensor. The beam splitter and blocking filter array are configured such that each selectable pair of incident sub-beams will cause reflections from a corresponding pair of internal facets, wherein a first incident sub-beam detects one of the internal facets and a second incident beam detects the other internal facet. For example, the first incident sub-beam will cause reflection (after being transmitted into optical element 102, through optical element 102, and transmitted into sample 10) from the i-th inner facet, and the second incident sub-beam will cause reflection (after being transmitted into optical element 102, through optical element 102, and transmitted into sample 10) from the j-th inner facet, where i and j are controllably selected. As will be readily appreciated by those skilled in the art, the parallelism radial deviation between the i-th and j-th inner facets can be extracted from the interference pattern thus formed on the optical sensor.

[0186] According to some implementations, each of the internal facets 14 can be inspected (probeed) one at a time, for example, using a slit or aperture-like optical mask or shutter assembly that can be translated. Figure 3 The illustration is schematically an optical-based system 300, corresponding to a specific implementation of system 100, and configured to verify the parallelism between the internal facets of a sample by examining the internal facets one at a time. More specifically, Figure 3 A cross-sectional side view of system 300 and sample 10 according to some embodiments is presented. (It should be understood that sample 10 does not constitute part of system 300.)

[0187] System 300 includes a light-transmitting optical element 302, an optical device 304, and an optional controller 308, which correspond to specific embodiments of optical element 102, optical device 104, and controller 108, respectively. Optical element 302 includes a substrate 332, a first optical element surface 334a, and a second optical element surface 334b, which correspond to specific embodiments of substrate 132, first optical element surface 134a, and second optical element surface 134b, respectively.

[0188] Optical device 304 includes an ICA 312 and an orientable retaining base 314, corresponding to specific embodiments of ICA 312 and retaining base 314, respectively. ICA 312 includes an autocollimator 352, which includes an image sensor (not shown). According to some embodiments, autocollimator 352 is a digital autocollimator or an electronic autocollimator. According to some embodiments, autocollimator 352 is a laser autocollimator. According to some embodiments, ICA 312 may also include an optical mask 356, which includes a slit 358. According to some embodiments, optical mask 356 may be translational to allow controllable positioning of slit 358 over any of the internal facets 14, thereby allowing each internal facet 14 to be examined one at a time. According to some such embodiments, optical device 304 may also include a motor 360, which may be mechanically associated with optical mask 356 to allow translation of optical mask 356. According to some implementations, motor 360 may be a linear stepper motor, which may be mechanically connected to optical mask 356 via screw 362.

[0189] It also indicates a computing module 346, which corresponds to a specific implementation of computing module 146. According to some implementations, computing module 346 may be included in system 300.

[0190] according to Figure 3 In some alternative implementations not depicted, instead of optical mask 356 (and motor 360), ICA 312 may include a shutter assembly comprising a plurality of individually openable and closable shutters. Each shutter may be positioned over a corresponding internal facet 14, thereby allowing each internal facet 14 to be examined one at a time.

[0191] In operation, according to some embodiments, the optical mask 356 is translated to position the slits 358 one after another above each of the inner facets 14. For example, and as... Figure 3As depicted, when slit 358 is positioned above the first inner facet 14a, a collimated beam (not all collimated beams are numbered) indicated by arrow 305 is projected onto optical mask 356 in a direction orthogonal to the first surface 334a of the optical element. The (first) incident portion of the collimated beam passes through slit 358, strikes the first surface 334a of the optical element perpendicularly, and is transmitted through the first surface 334a into optical element 302, thus obtaining a transmitted beam. The first incident portion is indicated by arrow 355a, and the transmitted beam is indicated by arrow 315a.

[0192] The transmitted beam travels through optical element 302, passes through the second surface 334b ​​of optical element and the first surface 16a of sample into sample 10, and propagates toward the first internal facet 14a. The transmitted beam is reflected from the first internal facet 14a toward the second surface 16b of sample. The first reflected beam—corresponding to the portion of the transmitted beam reflected away from the first internal facet 14a—is indicated by arrow 325a. A first double-reflected beam is obtained by reflecting the first reflected beam from the second surface 16b of sample toward the first surface 16a of sample. The first double-reflected beam is indicated by arrow 335a. The first double-reflected beam (i.e., reflected twice: once from the first internal facet 14a and then from the second surface 16b of sample) exits from sample 10 and enters optical element 302 via the first surface 16a of sample and the second surface 334b ​​of optical element. The first double-reflected beam travels to the first surface 334a of optical element and exits from optical element 302 (e.g., refracted), thereby obtaining a first returning beam. The first returning beam is indicated by arrow 345a. The first returning beam travels to the autocollimator 352 after passing through the slit 358 and is sensed by the image sensor of the autocollimator 352.

[0193] The trajectories of the second incident portion, the second transmitted beam, the second reflected beam, the second double-reflected beam, and the second returning beam are indicated by dashed arrows 355b, 315b, 325b, 335b, and 345b, respectively. This trajectory is achieved when the optical mask 356 is translated such that the slit 358 is positioned above the second inner facet 14b. Arrows 355b, 315b, 325b, 335b, and 345b are shown as dashed lines to indicate that this trajectory is not achieved when the slit 358 is positioned above the first inner facet 14a (i.e., no corresponding beam exists when the slit 358 is positioned above the first inner facet 14a). The trajectories of the third incident portion, the third transmitted beam, the third reflected beam, the third double-reflected beam, and the third returning beam are indicated by dashed arrows 355c, 315c, 325c, 335c, and 345c, respectively. The trajectory is achieved when the optical mask 356 is translated such that the slit 358 is positioned above the third inner facet 14c. Arrows 355c, 315c, 325c, 335c, and 345c are indicated by dashed lines to show that the trajectory is not achieved when the slit 358 is positioned above the first inner facet 14a (i.e., there is no corresponding beam when the slit 358 is positioned above the first inner facet 14a).

[0194] According to some implementations, the optical mask 356 can be continuously translated. When the transmitted light is scanned along the inner facets, the corresponding spot formed on the image sensor of the autocollimator 352 remains substantially fixed (unless the inner facets are bent, flexed, and / or otherwise deformed). When the transmitted beam is transferred to an adjacent inner facet, a new spot is formed on the image sensor (when the two inner facets are sufficiently misaligned). Once the transfer is complete, only the new spot remains on the image sensor.

[0195] According to some alternative embodiments, the optical mask 356 can be moved between different positions among a plurality of locations. At each of these locations, the slit 358 is correspondingly positioned above one of the inner facets 14. The collimated beam 305 can only be projected when the optical mask 356 is in one of the (different) locations.

[0196] In order not to hinder Figure 3 The light beam reflected off the first surface 334a of the optical element is not shown.

[0197] Also refer to Figure 4 , Figure 4A light spot 401 on a digital display 464 of an autocollimator 352 according to some embodiments of system 300 is schematically depicted, wherein the first surface 334a of the optical element is coated with an anti-reflective coating. According to some embodiments, the light spot 401 includes a first light spot 401a, a second light spot 401b, and a third light spot 401c. Since the internal facets 14 are examined one at a time, it is known which returned beam generated each light spot 401, and therefore which internal facet 14 generated each light spot 401. Thus, the parallelism deviation between each pair of internal facets 14 can be calculated. The first light spot 401a is generated by the first returned beam (in... Figure 3 (as indicated by arrow 345a). The second spot 401b is formed by the second returning beam (in...). Figure 3 (Indicated by arrow 345b). The third spot 401c is formed by the third returning beam (in...). Figure 3 The middle part is formed by arrow 345c.

[0198] Two-dimensional vector u1=(u 1,x ,u 1,y ), u2=(u 2,x ,u 2,y ) and u3=(u 3,x ,u 3,y The coordinates (e.g., center points) of the first spot 401a, the second spot 401b, and the third spot 401c are specified respectively. The pitch and roll deviations between each pair of inner facets 14 can be calculated based on the values ​​of the components u1, u2, and u3.

[0199] According to some embodiments in which a focusing lens (not shown; for example, the focusing lens of an autocollimator) with a focal length of f2 is used to focus the returned beam onto an image sensor (e.g., the image sensor of an autocollimator), by appropriately selecting a coordinate system, the beam can be focused via tan(δ) 21,p )=(u 2,x -u 1,x ) / f2 and tan(δ 21,r )=(u 2,y -u 1,y The pitch deviation δ of the second returning beam relative to the first returning beam is calculated using f / 2. 21,p and roll deviation δ 21,r Similarly, it can be obtained through tan(δ) 31,p )=(u 3,x -u 1,x ) / f2 and tan(δ 31,r )=(u 3,y -u 1,y The pitch deviation δ of the third returning beam relative to the first returning beam is calculated using f / 2. 31,p and roll deviation δ31,r And can be obtained separately via tan(δ) 32,p )=(u 3,x -u 2,x ) / f2 and tan(δ 32,r )=(u 3,y -u 2,y The pitch deviation δ of the third returning beam relative to the second returning beam is calculated using f / 2. 32,p and roll δ 32,r Therefore, the relation n can be used separately. s ·sin(2ε 21,p )=sin(δ 21,p ) and n s ·sin(2ε 21,r )=sin(δ 21,r To calculate the pitch parallelism deviation ε of the second inner facet 14b relative to the first inner facet 14a. 21,p and roll parallelism deviation ε 21,r n can be used separately. s ·sin(2ε 31,p )=sin(δ 31,p ) and n s ·sin(2ε 31,r )=sin(δ 31,r To calculate the pitch parallelism deviation ε of the third inner plane 14c relative to the first inner plane 14a. 31,p and roll parallelism deviation ε 31,r n can be used separately. s ·sin(2ε 32,p )=sin(δ 32,p ) and n s ·sin(2ε 32,r )=sin(δ 32,r To calculate the pitch parallelism deviation ε of the third inner facet 14c relative to the second inner facet 14b. 32,p and roll parallelism deviation ε 32,r .

[0200] Relational expressions can be used separately. and n s ·sin(2ε 21 )=sin(δ 21 ), And n s ·sin(2ε 31 )=sin(δ 31 )as well as And n s ·sin(2ε 32 )=sin(δ 32To calculate the magnitude of the parallelism deviation (i.e., radial deviation) of the second inner plane 14b relative to the first inner plane 14a, the third inner plane 14c relative to the first inner plane 14a, and the third inner plane 14c relative to the second inner plane 14b.

[0201] According to some implementations where the parallelism deviation is sufficiently small, a small-angle approximation can be used. As will be apparent to those skilled in the art, under a small-angle approximation (when treated in radians), ε 21,p =(u 2,x -u 1,x ) / (2n s ·f2) and ε 21,r =(u 2,y -u 1,y ) / (2n s ·f2), ε 31,p =(u 3,x -u 1,x ) / (2n s ·f2) and ε 31,r =(u 3,y -u 1,y ) / (2n s ·f2) and ε 32,p =(u 3,x -u 2,x ) / (2n s ·f2) and ε 32,r =(u 3,y -u 2,y ) / (2n s ·f2).

[0202] According to some embodiments, the calculation module 346 can be configured to calculate the parallelism deviation between some or all pairs of internal facets in the test sample. According to some embodiments (particularly embodiments with a large number of internal facets), the calculation module 346 can be configured to calculate the parallelism deviation between all pairs of adjacent internal facets in the test sample. According to some such embodiments, the calculation module 346 can be configured to calculate the parallelism deviation of one of the internal facets (e.g., the first or last internal facet) relative to all other facets. According to some embodiments, the calculation module 346 can also be configured to additionally calculate the uncertainty of the calculated parallelism deviation.

[0203] Figure 5A stage assembly 538, on which a sample 10 is disposed, is schematically depicted according to some embodiments. An optical element 502 disposed on the sample 10 is also depicted. The stage assembly 538 and the optical element 502 correspond to specific embodiments of the stage assembly 138 and the optical element 102 of the system 100. The second surface 534b of the optical element is inclined at an angle σ′ relative to the first surface 534a of the optical element. The first surface 534a and the second surface 534b of the optical element correspond to specific embodiments of the first surface 134a and the second surface 134b of the optical element, respectively.

[0204] The stage assembly 538 includes a pitch goniometer 572, a roll goniometer 574, and a tilting platform 576. According to some embodiments, and as... Figure 5 As depicted, a tilting platform 576 is mounted on a roll goniometer 574, which in turn is mounted on a pitch goniometer 572. The tilting platform 576 includes an outer, flat platform top surface 578a and an outer, flat platform base surface 578b opposite to the platform top surface 578a. According to some embodiments, the platform top surface 578a is tilted relative to the base surface 578b at a platform tilt angle ι approximately equal to σ'.

[0205] The orientation of the tilting platform 576, and thus the orientation of the sample 10 and the optical element 502, can be adjusted by orienting the pitch goniometer 572 and the roll goniometer 574, thereby allowing the incident angle of a light beam projected onto the optical element 502, for example, via an ICA (not shown), to be controllably set. According to some embodiments, each of the pitch goniometer 572 and the roll goniometer 574 can be oriented using a programmable micrometer (not shown). Additionally or alternatively, according to some embodiments, each of the pitch goniometer 572 and the roll goniometer 574 can be manually oriented.

[0206] Figure 6A and Figure 6B An optical-based system 600 for measuring internal facets in a sample, according to some embodiments, is schematically depicted. Figure 6B yes Figure 6A A magnified view of the portion depicted by the dashed line L'. The optically based system 600 is configured to verify the parallelism between the internal facets of the sample. More specifically, Figure 6A A cross-sectional side view of a system 600 and a sample 60 according to some embodiments is presented, wherein the sample 60 is undergoing an inspection performed by the system 600. (It should be understood that the sample 600 does not constitute part of the system 600.)

[0207] Sample 60 includes a light-transmitting substrate 62 and two or more internal facets 64 embedded in the substrate 62. The substrate 62 may be made of material with a refractive index n.s The sample 60 also includes an outer first surface 66a (also referred to as the "sample first surface") and an outer second surface 66b (also referred to as the "sample second surface"). The sample second surface 66b is opposite to the sample first surface 66a. Each of the sample first surface 66a and the sample second surface 66b may be flat. According to some embodiments, and as... Figure 6A and Figure 6B As depicted, the second surface 66b of the sample is parallel to the first surface 66a of the sample. According to some embodiments, each internal facet 64 constitutes a thin semi-reflective or reflective layer embedded in the substrate 62. According to some embodiments, the sample 60 may be a one-dimensional or two-dimensional reflective waveguide. According to some such embodiments, the first surface 66a and the second surface 66b of the sample constitute the main surface of the waveguide.

[0208] Sample 60 may be similar to Sample 10, but according to some embodiments, Sample 60 may differ from Sample 10 in its internal dimensions (or at least its proportions)—particularly in the ratio of d1′ / d2′ to d1 / d2, as detailed below—and in its refractive index. Here, d1′ is the distance between the first surface 66a and the second surface 66b of the sample, and d2′ is the distance between adjacent internal facets (e.g., internal facets 64a and 64b, internal facets 64b and 64c). Figure 6B d1′ and d2′ are shown in the figure.

[0209] The sample portion 68 of sample 60 corresponds to the portion (e.g., a segment) where the internal facet 64 of substrate 62 is located (while the portion of sample 60 complementary to sample portion 68 may not have any internal facet 64). As a non-limiting example intended to facilitate the description by making it more specific, Figure 6A and Figure 6B In the diagram, the inner facet 64 is shown as comprising three inner facets: a first inner facet 64a, a second inner facet 64b, and a third inner facet 64c, wherein the second inner facet 64b is disposed between the first inner facet 64a and the third inner facet 64c. Those skilled in the art will readily recognize that the three-inner-facet configuration encompasses the nature of any number of inner facets (e.g., 4, 5, 10, or more).

[0210] The internal facets 64 are nominally parallel. In reality, due to manufacturing defects, the internal facets 64 may not typically exhibit perfect parallelism. According to some embodiments, each internal facet 64 is positioned at a nominal angle μ′ of approximately 90° relative to the first surface 66a of the sample. nom (Spanning a plane parallel to the zx plane) nominally inclined. According to some such embodiments, and as... Figure 6Aand Figure 6B As shown, the internal facet 64 is nominally orthogonal to the first sample surface 66a (and, in an embodiment where the second sample surface 66b is parallel to the first sample surface 66a), i.e., μ′ nom = 90°. However, in practice, each internal facet 64 can be oriented at its own actual angle, which is different from the nominal angle μ′. nom There are slight differences. The first internal facet 64a, the second internal facet 64b, and the third internal facet 64c are oriented relative to the first surface 66a of the sample at a first angle μ′1, a second angle μ′2, and a third angle μ′3, respectively.

[0211] It should be noted that due to manufacturing defects, the actual angle μ′ i (i = 1, 2, 3) may be each other and / or with the nominal angle μ′ nom The differences lie not only in the magnitude but also in the corresponding plane of inclusion, as explained above for sample 10.

[0212] Each of the first sample surface 66a and the second sample surface 66b extends from the first end 61a of the sample 60 to the second end 61b. The sample portion 68 defines a first region 63a and a second region 63b on the first sample surface 66a and the second sample surface 66b, respectively, wherein an internal facet 64 is positioned between the first region 63a and the second region 63b.

[0213] According to some embodiments, system 600 includes a first optical element (FOE) 602, a second optical element (SOE) 682, and an optical device 604. Each of FOE 602 and SOE 682 is light-transmitting. System 600 may also include a controller 608 functionally associated with and configured to control the operation of optical device 604, substantially as described with respect to controller 108 and optical device 104 of system 100. According to some embodiments, and as... Figure 6AThe depicted optical device 604 includes an illumination and collection assembly (ICA) 612 and a holding base structure 614 for mounting a sample 60 thereon. According to some embodiments, the holding base structure 614 may include an orientation base structure configured to allow controllable orientation of the sample 60. The ICA 612 includes a light source 622 (or multiple light sources) and a photosensing element 624, which may be similar to the light source 122 and photosensing element 124 of system 100, respectively. According to some embodiments, the photosensing element 624 may be a camera device. According to some embodiments, the ICA 612 may also include an optical device 628, whose function may be similar to that of the optical device 128 of system 100.

[0214] FOE 602 includes a substrate 632, which constitutes the body of FOE 602 and is made of a material having approximately the same refractive index as substrate 62 (e.g., greater than n). s -0.02 and less than n s The substrate 632 is made of a material with a refractive index of 0.02 (±0.02). According to some embodiments, the substrate 632 is made of a material having the same refractive index as the substrate 62. The FOE 602 also includes an outer first surface 634a and an opposite outer second surface 634b. According to some embodiments, and as... Figure 6A As depicted, the first surface 634a of the FOE is flat. According to some such embodiments, and as... Figure 6A As depicted, the second surface 634b of the FOE is also flat and inclined relative to the first surface 634a of the FOE. According to some embodiments, the FOE 602 is a prism. According to some such embodiments, the prism may be a triangular prism.

[0215] SOE 682 includes a substrate 692, which constitutes the body of SOE 682 and is made of a material having approximately the same refractive index as the substrate 62 (e.g., greater than n). s -0.02 and less than n s The substrate 692 is made of a material having a refractive index of 0.02 (±0.02). According to some embodiments, the substrate 692 is made of a material having the same refractive index as the sample 60. The SOE 682 also includes an outer first surface 694a and an opposite outer second surface 694b. According to some embodiments, and as... Figure 6A As depicted, the SOE first surface 694a is flat. According to some such embodiments, and as... Figure 6AAs depicted, the second surface 694b of the SOE is also flat and inclined relative to the first surface 694a of the SOE. According to some embodiments, the SOE 682 is a prism. According to some such embodiments, the prism may be a triangular prism. According to some embodiments, the SOE 682 has the same dimensions or at least the same proportions as the FOE 602.

[0216] According to some embodiments, the second surface 634b of the FOE and the second surface 694b of the SOE can be inclined relative to the first surface 634a of the FOE and the first surface 694a of the SOE with a first inclination angle σ1 (σ1 is included parallel to zx) and a second inclination angle σ2 (σ2 is included parallel to zx), respectively. According to some embodiments, σ2 is approximately equal to σ1. Figure 6B The text indicates σ1 and σ2.

[0217] According to some embodiments, particularly in which (i) the first sample surface 66a and the second sample surface 66b are parallel, (ii) the internal plane 64 is nominally orthogonal to each of the first sample surface 66a and the second sample surface 66b, and (iii) adjacent internal planes are spaced apart at regular intervals, each of σ1 and σ2 can be equal to (90° - arctan(d1′ / d2′)), that is, 90 degrees minus arctan(d1 / d2). The reason for choosing the above tilt angle is explained below.

[0218] ICA 612 is configured to output a collimated beam generated by light source 622 and optionally manipulated (e.g., collimated) by optical device 628 (in embodiments including optical device 628). According to some embodiments, optical device 628 may include a collimating lens or collimating lens assembly (not shown). The relative orientation of FOE 602 and ICA 612 (more precisely, the illumination component of ICA 612) can be (controllably) set such that the beam output by ICA 612 illuminates the first surface 634a of FOE perpendicularly or at least approximately perpendicularly to it (e.g., within 1°, 1.5°, or even 2° of perpendicular incidence).

[0219] According to some embodiments, the optical device 628 may also include a translatable slit or aperture optical mask (not shown; for example...). Figure 7 The optical device 628 may include a translationally slit optical mask configured to control the irradiation (i.e., impact) position of a light beam (e.g., a laser beam) on the first surface 634a of the FOE, thereby allowing individual inspection of each internal facet 64. Alternatively, according to some embodiments, the optical device 628 may also include a plurality of shutters configured to allow (enable) individual inspection of each internal facet 64.

[0220] According to some embodiments, the retaining base structure 614 can be configured to mount or retain the sample 60 between FOE 602 and SOE 682, such that each of FOE 602 and SOE 682 is adjacent to the sample 60. More specifically, according to some such embodiments, the relative positioning of the sample 60 and FOE 602 can such that the second surface 634b of the FOE is adjacent and optionally parallel to the first surface 66a of the sample, and the relative positioning of the sample 60 and SOE 682 can such that the second surface 694b of the SOE is adjacent and optionally parallel to the second surface 66b of the sample.

[0221] According to some embodiments, the retaining base structure 614 may include a platform 638, which includes a slit (or hole) 696 extending from a top surface 698 of the platform 638 into the platform 638. The slit 696 is configured to receive a sample 60 therein, such that a sample portion 68 protrudes from the slit 696. The platform 638 is also configured for mounting an FOE 602 and an SOE 682 thereon, wherein a first surface 634a of the FOE is adjacent to and parallel to a first region 63a, and a second surface 694b of the SOE is adjacent to and parallel to a second region 63b.

[0222] According to some implementations, platform 638 can be manipulated in six degrees of freedom.

[0223] In operation, according to some embodiments, the extended and collimated incident beam (not all extended and collimated incident beams are numbered) indicated by arrow 605 is projected onto the FOE first surface 634a approximately perpendicularly. According to some embodiments, the incident beam can be projected perpendicularly onto the FOE first surface 634a.

[0224] An incident light beam (or at least a portion thereof) is transmitted through (i.e., via) the first surface 634a of the FOE into the FOE 602, thus obtaining a transmitted light beam. The transmitted light beam is indicated by arrow 615 (not all transmitted light beams are numbered). The transmitted light beam travels through the FOE 602, passes through (i.e., is transmitted into) the sample 60 via the second surface 634b of the FOE and the first surface 66a of the sample, and propagates towards the inner facet 64. The transmitted light beam is reflected from the inner facet 64 towards the second surface 66b of the sample.

[0225] More specifically, since the internal facets 64 may differ slightly from each other in their respective orientations, the transmitted beam can be reflected off each internal facet 64 at slightly different angles. Therefore, multiple reflected beams can be obtained, each slightly different in its propagation direction. The first reflected beam—corresponding to the portion of the transmitted beam reflected off the first internal facet 64a—is indicated by arrow 625a. The second reflected beam—corresponding to the portion of the transmitted beam reflected off the second internal facet 64b—is indicated by arrow 625b. The third reflected beam—corresponding to the portion of the transmitted beam reflected off the third internal facet 64c—is indicated by arrow 625c.

[0226] The reflected beam exits from sample 60 via sample second surface 66b and enters SOE 682 via SOE second surface 694b. Next, the reflected beam travels to SOE first surface 694a and exits from SOE 682 (e.g., refracted), thus obtaining (secondary) multiple beams (also referred to as "outgoing beams"): the first outgoing beam caused by the refraction of the first reflected beam from SOE 682 is indicated by arrow 635a. The second outgoing beam caused by the refraction of the second reflected beam from SOE 682 is indicated by arrow 635b. The third outgoing beam caused by the refraction of the third reflected beam from SOE 682 is indicated by arrow 635c. The outgoing beams propagate toward ICA 612, are focused by optical device 628 onto photosensing element 624, and are thereby sensed (e.g., by an image sensor included in photosensing element 624).

[0227] According to some implementations, each of σ1 and σ2 is equal to (90° - arctan(d1′ / d2′)). (By reading...) Figure 6A and Figure 6B Clearly, the above selection of σ1 and σ2 ensures that virtually every ray (or at least a portion thereof) in the reflected beam exits from the sample 60 via the second surface 66b of the sample and is transmitted into the SOE 682 without being reflected again by any internal facet 14 or the first surface 66a of the sample. Therefore, the above selection of σ1 and σ2 reduces losses, thereby improving the detection of the returning beam (e.g., by ensuring that the returning beam forms a bright spot on the photosensitive surface of the image sensor). According to some embodiments, σ1 and σ2 may each be equal to approximately (90° - arctan(d1′ / d2′)).

[0228] According to some embodiments, the first surface 634a of the FOE and the first surface 694a of the SOE may each be coated with an anti-reflective coating to increase the intensity of light transmitted into the FOE 602 and refracted out of the SOE 682.

[0229] In order not to hinder Figure 6A and Figure 6B The light beam reflected off the first surface 634a of the FOE is not shown.

[0230] According to some embodiments, controller 608 may be communicatively associated with computing module 646. Computing module 646 may include one or more processors and volatile and / or non-volatile memory components. One or more processors may be configured to receive raw or processed sensing data obtained from photosensing component 624 from controller 608, and calculate, based on the sensing data, overall parallelism deviation (e.g., average or maximum) and / or parallelism deviation between pairs of internal facets 64, substantially as detailed in the description of system 100 above. Raw sensing data may include the intensity of pixels constituting a spot formed by an outgoing light beam focused on photosensing component 624. Processed sensing data may include the center point of the spot formed by the outgoing light beam and the angular deviation between (pairs of) outgoing light beams. According to some such embodiments, computing module 646 may be configured to process the raw sensing data obtained from photosensing component 624 to obtain the angular deviation between (pairs of) outgoing light beams.

[0231] According to some embodiments, one or more processors may include a graphics processing unit (GPU) configured to execute image recognition software to identify light spots formed by an outgoing light beam on an image sensor included in the light sensing component 624. According to some embodiments, a computing module 646 may be included in system 600.

[0232] The magnitude of the parallelism deviation between the internal facets can be inferred from the angular deviation between the emitted beams, essentially as described in the above description of system 100. The angular deviation can be derived from sensing data of the emitted beam obtained using the photosensing component 624 (e.g., based on the coordinates of the spot formed by the emitted beam on the image sensor of the photosensing component 624), essentially as detailed above in the description of system 100. According to some embodiments, the derivation of the angular deviation may involve using image recognition software, and optionally, other software (both of which can be executed by the calculation module 146) to identify the spot formed by the emitted beam on the image sensor, calculate the coordinates of the spot (e.g., its center point), etc., essentially as detailed above in the description of system 100.

[0233] As a non-limiting example, according to some implementations, where a collimating lens with a focal length of f1′ is used to focus the outgoing beam onto an image sensor (e.g., an autocollimator), the relation can be used. and n ssin(2ε′) max )=sin(δ′ max To obtain the maximum radial deviation ε′ of the parallelism between the (paired) internal facets 64. max Here, u′ α =(u′ α,x ,u′ α,y ), u′ β =(u′ β,x ,u′ β,y ) and u′ γ =(u′ γ,x ,u′ γ,y ) is a two-dimensional vector that specifies the coordinates of the first spot, the second spot, and the third spot formed on the image sensor by the emitted light beam.

[0234] According to some implementation methods, relational expressions can be used. and and n s sin(2ε′) γβ )=sin(δ′ γβ ), n s sin(2ε′) αγ )=sin(δ′ αγ ) and n s sin(2ε′) βα )=sin(δ′ βα To obtain the average radial deviation ε′ of the parallelism between the internal facets 64. avg , where ε′ avg =(ε′) γβ +ε′ αγ +ε′ βα ) / 3. Here, δ′ γβ It is the magnitude of the angle between the emitted beams that form the third and second beam spots. δ′ αγ It is the magnitude of the angle between the emitted beams that form the first and third light spots. δ′ βα It is the magnitude of the angle between the emitted beams forming the second and first light spots. ε′ γβ It is the radial deviation between the two internal small planes from which the outgoing beams that form the third and second beam spots are reflected. ε′ αγ ε′ is the radial deviation between the two internal small planes from which the emitted beams, forming the first and third light spots respectively, are reflected. βα This refers to the radial deviation between the two internal small planes from which the emitted beams, forming the second and first light spots respectively, are reflected. This can be compared with the above... Figure 2A In the description (about u) α u β and uγ The same method described in detail is based on u′ α u′ β and u′ γ Similar expressions for the average pitch deviation and average roll deviation between the internal planes 64 are derived.

[0235] Based on some implementations where the parallelism deviation is sufficiently small, a small-angle approximation can be used. In the case of a small-angle approximation (when processed in radians), and Similarly, ε′ γβ,p =|u′ β,x -u′ γ,x | / (2n s ′·f1′),ε′ αγ,p =|u′ γ,x -u′ α,x | / (2n s ′·f1′) and ε′ βα,p =|u′ α,x -u′ β,x | / (2n s ′·f1′) and ε′ γβ,r =|u′ β,y -u′ γ,y | / (2n s ′·f1′),ε′ αγ,r =|u′ γ,y -u′ α,y | / (2n s ′·f1′) and ε′ βα,r =|u′ α,y -u′ β,y | / (2n s According to some implementations, and as ′·f1′). Figure 6A and Figure 6B As depicted, sample 60 can be sandwiched between FOE 602 and SOE 682, such that the second surface 634b of FOE and the second surface 694b of SOE are in complete contact with the entire first region 63a and the entire second region 63b, respectively. In this embodiment, the transmitted light beam enters sample 60 directly from FOE 602, while the reflected light beam enters SOE 682 directly from sample 60.

[0236] According to some embodiments, the second surface 634b of the FOE does not contact the first surface 66a of the sample, and the second surface 694b of the SOE does not contact the second surface 66b of the sample. According to some such embodiments, refractive index-matched shape-plastic interfaces (not shown) can be inserted between the FOE 602 and the sample 60, and between the SOE 682 and the sample 60, substantially as described above in the description of system 100. The shape-plastic interfaces may have approximately the same (e.g., greater than n) shape as the substrate 62. s -0.02 and less than n s The refractive index is 0.02 (+0.02).

[0237] According to some alternative embodiments not depicted in the figures, instead of optical device 604, system 600 may include an interferometric measuring device and may extract information from the interference pattern formed by the outgoing beam, including radial deviations in parallelism between the pair of internal facets 64. According to some such embodiments, the interferometric measuring device may include a beam splitter array and an associated array of controllably opening and closing blocking filters configured to allow examination of the pair of internal facets one at a time. More specifically, the beam splitter and blocking filter array may be configured to (i) split the incident beam into a selectable pair of incident sub-beams perpendicularly incident on FOE 602, and (ii) recombine the two outgoing sub-beams (i.e., the sub-beams emanating from SOE 682)—caused respectively by the pair of incident beams—into a single combined outgoing beam, which is then sensed by an image sensor. The beam splitter and blocking filter array are configured such that each selectable pair of incident sub-beams will cause reflection from a corresponding pair of internal facets, wherein the first incident sub-beam probes one of the internal facets and the second incident sub-beam probes the other internal facet. For example, the first incident sub-beam will cause reflection from the i-th internal facet (after transmission into FOE 602, through FOE 602 and into sample 60), and the second incident beam will cause reflection from the j-th internal facet (after transmission into FOE 602, through FOE 602 and into sample 60), where i and j are controllably selectable. As will be readily appreciated by those skilled in the art, the parallelism radial deviation between the i-th and j-th internal facets can be extracted from the interference pattern thus formed on the optical sensor.

[0238] According to some implementations, each of the internal facets 64 can be inspected (probeed) one at a time, for example, using a slit or aperture-like optical mask or shutter assembly that can be translated. Figure 7 The illustration is schematically an optical-based system 700, corresponding to a specific implementation of system 600, and configured to verify the parallelism between the internal facets of a sample by examining the internal facets one at a time. More specifically, Figure 7 A cross-sectional side view of system 700 and sample 60 according to some embodiments is presented. (It should be understood that sample 60 does not constitute part of system 700.)

[0239] System 700 includes a light-transmitting FOE 702, a light-transmitting SOE 782, an optical device 704, and an optional controller 708, corresponding to specific embodiments of FOE 602, SOE 682, optical device 604, and controller 608, respectively. FOE 702 includes a first FOE surface 734a and a second FOE surface 734b, corresponding to specific embodiments of first FOE surface 634a and second FOE surface 634b, respectively. SOE 782 includes a first SOE surface 794a and a second SOE surface 794b, corresponding to specific embodiments of first SOE surface 694a and second SOE surface 694b, respectively.

[0240] Optical device 704 includes an ICA 712 and a holding base structure 714, corresponding to specific embodiments of ICA 612 and holding base structure 614, respectively. ICA 712 includes a light source 722, an image sensor 724, a collimating lens 740, and a focusing lens 750. According to some embodiments, ICA 712 may also include an optical mask 756, which includes a slit 758. According to some embodiments, the optical mask 756 may be translational to allow the slit 758 to be controllably positioned over any one of the internal facets 64, thereby allowing each internal facet 64 to be inspected one at a time. According to some such embodiments, optical device 704 may also include a motor 760, which may be mechanically associated with the optical mask 756 to allow translation of the optical mask 756. According to some embodiments, the motor 760 may be a linear stepper motor, which may be mechanically coupled to the optical mask 756 via a screw 762.

[0241] The document also indicates a platform 738 for maintaining infrastructure 714. Platform 738 corresponds to a specific implementation of platform 638 for maintaining infrastructure 614.

[0242] It also indicates a computing module 746, which corresponds to a specific implementation of computing module 646. According to some implementations, computing module 746 may be included in system 700.

[0243] according to Figure 7 In some alternative implementations not depicted, instead of the optical mask 756 (and motor 760), the ICA 712 may include a shutter assembly comprising a plurality of individually openable and closable shutters. Each shutter may be positioned above a corresponding internal facet 64, thereby allowing each internal facet 64 to be examined one at a time.

[0244] In operation, according to some implementations, the optical mask 756 is translated to position the slits 758 one after another above each of the inner facets 64. For example, and as... Figure 7 As depicted, when slit 758 is positioned above the first inner facet 64a, a collimated beam (not all collimated beams are numbered) indicated by arrow 705 is projected onto optical mask 756 in a direction orthogonal to the first surface 734a of the FOE. (More specifically, the light generated by light source 722 can be collimated by collimating lens 740 to prepare a collimated beam.) The (third) incident portion of the collimated beam passes through slit 758, illuminates the first surface 734a of the FOE perpendicularly, and is transmitted through the first surface 734a of the FOE into FOE 702, thereby obtaining a (third) transmitted beam. The incident portion is indicated by arrow 745c, and the transmitted beam is indicated by arrow 715c.

[0245] The transmitted light beam travels through FOE 702, passes through (i.e., is transmitted into) sample 60 via FOE second surface 734b and sample first surface 66a, and propagates toward third inner facet 64c. The transmitted light beam is reflected from third inner facet 64c toward sample second surface 66b, thus obtaining a (third) reflected light beam. The reflected light beam is indicated by arrow 725c. The reflected light beam exits from sample 60 into SOE 782 via sample second surface 66b and SOE second surface 794b. The beam travels to SOE first surface 794a and exits from SOE 782 (e.g., is refracted), thus obtaining a third exited light beam. The exited light beam is indicated by arrow 735c. The exited light beam passes through slit 758, is focused by focusing lens 750 onto image sensor 724, and is thereby sensed.

[0246] The trajectories of the first incident portion, the first transmitted beam, the first reflected beam, and the first emitted (e.g., refracted) beam are indicated by dashed arrows 745a, 715a, 725a, and 735a, respectively. This trajectory is achieved when the optical mask 756 is translated such that the slit 758 is positioned above the first inner facet 64a. Arrows 745a, 715a, 725a, and 735a are shown as dashed lines to indicate that this trajectory is not achieved when the slit 758 is positioned above the third inner facet 64c (i.e., no corresponding beam exists when the slit 758 is positioned above the third inner facet 64c). The trajectories of the second incident portion, the second transmitted beam, the second reflected beam, and the second emitted (e.g., refracted) beam are indicated by dashed arrows 745b, 715b, 725b, and 735b, respectively. This trajectory is achieved when the optical mask 756 is translated such that the slit 758 is positioned above the second inner facet 64b. Arrows 745b, 715b, 725b and 735b are shown by dashed lines to indicate that the trajectory was not achieved when slit 758 was positioned above the third inner facet 64c (i.e., there was no corresponding beam when slit 758 was positioned above the third inner facet 64c).

[0247] In order not to hinder Figure 7 The light beam reflected off the first surface 734a of the FOE is not shown.

[0248] According to some embodiments, the optical mask 756 can be continuously translated, essentially as described above with respect to the optical mask 356 of system 300. According to some alternative embodiments, the optical mask 756 can be moved between different positions in a plurality of locations, essentially as described above with respect to the optical mask 356 of system 300.

[0249] Based on the angular deviation between the two emitted beams, the parallelism deviation between the two internal facets that can be tracked by the two beams can be inferred, essentially as detailed in the description of system 300 above. The angular deviation can be calculated based on sensing data of the two emitted beams (e.g., based on the center point of the spot formed by the two emitted beams on the image sensor 724). This is illustrated below by way of non-limiting example, in some embodiments, a focusing lens 750 with a focal length of f2′ is used to focus the emitted beams onto the image sensor 724.

[0250] Two-dimensional vector u1′=(u1′ ,x ,u1′ ,y ), u2′=(u2′ ,x ,u2′ ,y ) and u3′=(u3′ ,x ,u3′ ,yThe coordinates (e.g., center points) of the first, second, and third light spots are specified respectively. The first light spot is caused by light reflected from the first inner facet 64a, the second light spot by light reflected from the second inner facet 64b, and the third light spot by light reflected from the third inner facet 64c. By appropriately choosing the coordinate system, the coordinates can be determined via tan(δ′). 21,p )=(u2′ ,x -u1′ ,x ) / f2′ and tan(δ′ 21,r )=(u2′ ,y -u1′ ,y The pitch deviation δ′ of the second returning beam relative to the first returning beam is calculated using f / f2′. 21,p and roll deviation δ′ 21,r Similarly, this can be achieved via tan(δ′) 31,p )=(u3′ ,x -u1′ ,x ) / f2′ and tan(δ′ 31,r )=(u3′ ,y -u1′ ,y The pitch deviation δ′ of the third returning beam relative to the first returning beam is calculated using f / f2′. 31,p and roll deviation δ′ 31,r And can be obtained separately via tan(δ′) 32,p )=(u3′ ,x -u2′ ,x ) / f2′ and tan(δ′ 32,r )=(u3′ ,y -u2′ ,y The pitch deviation δ′ of the third returning beam relative to the second returning beam is calculated using f / f2′. 32,p and roll deviation δ′ 32,r Therefore, the relation n can be used separately. s sin(2ε′) 21,p )=sin(δ′ 21,p ) and n s sin(2ε′) 21,r )=sin(δ′ 21,r To calculate the pitch parallelism deviation ε′ of the second inner facet 64b relative to the first inner facet 64a. 21,x and roll parallelism deviation ε′ 21,y n can be used separately. s sin(2ε′) 31,p )=sin(δ′ 31,p ) and n s sin(2ε′) 31,r )=sin(δ′31,r To calculate the pitch parallelism deviation ε′ of the third inner facet 64c relative to the first inner facet 64a. 31,p and roll parallelism deviation ε′ 31,r n can be used separately. s sin(2ε′) 32,p )=sin(δ′ 32,p ) and n s sin(2ε′) 32,r )=sin(δ′ 32,r To calculate the pitch parallelism deviation ε′ of the third inner facet 64c relative to the second inner facet 64b. 32,p and roll parallelism deviation ε′ 32,r .

[0251] According to some implementations where the parallelism deviation is sufficiently small, a small-angle approximation can be used. As will be apparent to those skilled in the art, under a small-angle approximation (when treated in radians), ε′ 21,p =(u2′) ,x -u1′ ,x ) / (2n s ′·f2′) and ε′ 21,r =(u2′) ,y -u1′ ,y ) / (2n s ′·f2′),ε′ 31,p =(u3′) ,x -u1′ ,x ) / (2n s ′·f2′) and ε′ 31,r =(u3′) ,y -u1′ ,y ) / (2n s ′·f2′), and ε′ 32,p =(u3′) ,x -u2′ ,x ) / (2n s ′·f2′) and ε′ 32,r =(u3′) ,y -u2′ ,y ) / (2n s (f2').

[0252] method

[0253] According to one aspect of some embodiments, an optical-based method is provided for measuring the internal facets of a sample. This method can be used to verify the parallelism between the internal facets of a sample. Figure 8 A flowchart of such a method (optics-based method 800) according to some embodiments is presented. Method 800 may include:

[0254] --Stage 810, wherein a sample to be inspected (e.g., sample 10 or 60) is provided. The sample includes samples with a refractive index n. s The light-transmitting substrate (e.g., substrate 12 or 62) and two or more nominally parallel internal facets (e.g., internal facets 14 or 64) embedded in the substrate. Each internal facet is oriented approximately orthogonally to the outer and flat first surface of the sample.

[0255] - Stage 820, where a value approximately equal to n is provided. s (For example, greater than n) s -0.02 and less than n s A (first) optical element with a refractive index of +0.02 (e.g., optical element 102 or 302 or FOE 602 or 702, or similar optical elements). The optical element includes an external and flat first surface and an external and flat second surface, the second surface being opposite to the first surface of the optical element and inclined at an acute (first) angle relative to the first surface.

[0256] - Stage 830, wherein the sample and optical element are positioned such that the second surface of the optical element is adjacent to the first surface of the sample.

[0257] - Stage 840, wherein a first plurality of light beams (also referred to as “incident beams”) are projected onto the first surface of the optical element approximately perpendicularly (e.g., within 2° of perpendicular incidence).

[0258] - Stage 850, wherein a second plurality of beams is obtained as a result of each of the first plurality of beams passing through an optical element, being transmitted into the sample, being reflected once from an internal facet and exiting the sample (i.e., being transmitted out).

[0259] - Stage 860, in which a second plurality of light beams are sensed (measured, for example, using a light sensing component 124).

[0260] - Stage 870, wherein, based at least on the sensing data obtained in stage 860, at least one parallelism deviation between at least some of the internal facets is calculated.

[0261] As used herein, the term "acquisition" can be used in both active and passive senses. Thus, for example, in stage 850, a second plurality of beams may be acquired, not as a result of any operation performed in stage 850, but as a consequence of the generation of the first plurality of beams in stage 840. Generally, a stage can describe an active operation performed by a user or by the system used to implement the method, and / or the result or effect of one or more operations performed in one or more earlier stages.

[0262] Method 800 can be used to verify the parallelism between internal facets of a sample (e.g., sample 10 or sample 60). In particular, method 800 can be used to verify the parallelism between internal facets of a one-dimensional waveguide and between internal facets of a two-dimensional waveguide.

[0263] As detailed above in their respective descriptions, method 800 can be implemented using an optical system such as any of systems 100, 300, 600 and 700 or similar systems.

[0264] According to some embodiments, a single optical element is employed, such as optical element 102 or optical element 302. According to some embodiments, as described above... Figures 1A to 1E In the description and in Figure 3 As described in the description, and as follows in Figure 9 As described in the description, a second or more beams are obtained after the beam (first) passes through the optical element and is reflected once from an internal facet, and then passes through the optical element again. According to some embodiments, the optical element may be a prism (e.g., a triangular prism).

[0265] According to some embodiments, a pair of optical elements may be employed: a first optical element (e.g., FOE 602 or 702) and a second optical element (e.g., SOE 682 or 782). According to some embodiments, as described above... Figure 6A and Figure 6B In the description and in Figure 7 In the description and below Figure 10 As described in the description, a second plurality of beams are obtained after the beam passes (single) through the first optical element, is transmitted into the sample, is reflected once from an internal facet, and passes (single) through the second optical element. According to some embodiments, each optical element may be a prism (e.g., a triangular prism).

[0266] According to some embodiments, in stage 840, the beams of the first plurality of beams constitute complementary portions of the collimated extended beam. According to some embodiments, the extended beam may be monochromatic. According to some such embodiments, the extended beam may be a laser beam.

[0267] According to some implementations, the internal facets are inspected sequentially, one after another. According to some such implementations, the internal facets can be inspected "continuously" by scanning the light spots on the internal facets one after another.

[0268] According to some embodiments, the internal facets are inspected (probeled) one at a time. More specifically, according to some embodiments, stages 840, 850, and 860 may be implemented N times, where N is the number of internal facets, and wherein, in each implementation, light is irradiated only on one of the internal facets, substantially as described above in the description of system 100 according to some embodiments thereof, in the description of system 600 according to some embodiments thereof, or in the description of system 300 and in the description of system 700.

[0269] According to some embodiments, where the image sensor is used to sense the beams in the second plurality of beams (e.g., when using a camera device and / or an autocollimator), stage 870 may include an initial sub-stage in which image recognition software is used to identify light spots formed by the beams in the second plurality of beams on the photosensitive surface of the image sensor (e.g., light spot 201, light spot 401, a light spot formed on the image sensor of system 600, or a light spot formed on image sensor 724). According to some embodiments, the initial sub-stage may further include assigning coordinates to each light spot, for example, determining the center point of the light spot. According to some embodiments, the center point may be determined by averaging the coordinates of each point constituting the intensity-weighted light spot.

[0270] According to some embodiments that examine the internal facets one at a time, in stage 870, the parallelism deviation between pairs of adjacent internal facets is calculated. Additionally or alternatively, according to some embodiments, the parallelism deviation between each internal facet (except for the reference internal facet) and a reference internal facet (e.g., the lateral facet) is calculated. According to some embodiments, the parallelism deviation between each pair of internal facets is calculated. According to some embodiments, based on the calculated deviations, one or more of the average parallelism deviation and / or maximum parallelism deviation are calculated. According to some embodiments, the average and / or maximum pitch and / or roll deviations can be calculated. (The following is in...) Figure 9 and Figure 10 The description details various ways to calculate the parallelism (mentioned above).

[0271] According to some embodiments, an optical-based method is provided for measuring the internal facets of a sample. This method can be used to verify the parallelism between the internal facets of a sample. Figure 9 A flowchart of such a method (optics-based method 900) according to some embodiments is presented. Method 900 may include:

[0272] --Stage 910, wherein a sample to be inspected (e.g., sample 10) is provided. The sample includes samples with a refractive index n. sA light-transmitting substrate and two or more nominally parallel internal facets (e.g., internal facet 14) embedded in the substrate. Each internal facet is oriented approximately orthogonally to an external and flat first surface and an external and flat second surface of the sample.

[0273] - Stage 920, wherein an optical element (e.g., optical element 102 or optical element 302) is provided, the optical element having approximately equal to n s (For example, greater than n) s -0.02 and less than n s The refractive index is 0.02 (+0.02). The optical element includes an external and flat first surface and an external and flat second surface, the second surface being opposite to the first surface of the optical element and inclined at an acute angle relative to the first surface.

[0274] - Stage 930, wherein the sample and optical element are positioned such that the second surface of the optical element is adjacent to the first surface of the sample.

[0275] - Stage 940, wherein a first plurality of light beams (also referred to as “incident beams”) are projected onto the first surface of the optical element approximately perpendicularly (e.g., within 2° of perpendicular incidence) to the first surface of the optical element.

[0276] - Stage 950, in which a second plurality of beams (also known as “return beams”) are obtained as a result of each incident beam passing through the optical element, being transmitted into the sample, being reflected once from the internal facet and the second surface of the sample, and passing through the optical element again.

[0277] - Stage 960, in which a second plurality of light beams are sensed (i.e., measured; for example, using a light sensing component 124).

[0278] - Stage 970, wherein, based at least on the sensing data obtained in stage 960, at least one parallelism deviation between at least some internal facets is calculated.

[0279] Method 900 corresponds to a specific implementation of method 800. Method 900 can be used to verify the parallelism between the internal facets of a sample (e.g., sample 10). Method 900 can employ the methods described above. Figures 1A to 5 This is achieved through optical-based systems (e.g., systems 100 and 300 or any of similar systems) as taught in the description.

[0280] According to some embodiments, for example, essentially as detailed above in the descriptions of system 100 and system 300 according to some embodiments thereof, stages 940, 950, and 960 are implemented using an autocollimator (e.g., autocollimator 352). According to some embodiments, the autocollimator includes an image sensor, and in stage 960, the image sensor senses a beam among a second plurality of beams. Alternatively, according to some embodiments, the autocollimator is a visual autocollimator, and the returned beam is sensed using an eyepiece assembly of the autocollimator (through which scale lines are viewed).

[0281] According to some embodiments in which (i) an image sensor is used to sense the returning beam, (ii) stage 970 includes an initial sub-stage in which image recognition software is used to identify the light spot formed by the returning beam on the photosensitive surface of the image sensor, and (iii) the first surface of the optical element is not coated with a reflective coating so that an additional light spot (e.g., light spot 211) can be formed on the photosensitive surface of the image sensor (i.e., by light directly reflected away from the first surface of the optical element), the image recognition software may also be configured to distinguish the additional light spot from the light spot formed by the returning beam.

[0282] According to some implementations where each of the returning beams can be traced back to a corresponding specific internal facet (e.g., by examining the internal facets one at a time), the relation tan(δ) can be used. ij,p )=(x i -x j ) / f1 and n s ·sin(2ε ij,p )=sin(δ ij,p To calculate the pitch deviation ε between the i-th and j-th inner planes. ij,p Similarly, the relation tan(δ) can be used. ij,r )=(y i –y j ) / f1 and n s ·sin(2ε ij,r )=sin(δ ij,r To calculate the roll deviation ε between the i-th and j-th inner facets. ij,y f1 is the focal length of the focusing lens or focusing lens assembly used to focus the returning beam onto the light-sensing component used to sense the returning beam. i and x j These are the x-coordinates of the determined i-th and j-th return beams (e.g., the horizontal coordinates of the center point of the light spot formed by the i-th and j-th return beams on the image sensor). y i and y jThese are the y-coordinates of the determined i-th and j-th return beams (e.g., the vertical coordinates of the center point of the spot formed by the i-th and j-th return beams on the image sensor). (By appropriately choosing the coordinate system, the tilt in pitch and the tilt in roll are decoupled, so that pitch only affects the value of the x-coordinate of the spot, and roll only affects the value of the y-coordinate of the spot.)

[0283] Relational expressions can be used and n s ·sin(2ε ij )=sin(δ ij To calculate the radial deviation ε of the parallelism between the i-th inner plane and the j-th inner plane. ij .

[0284] According to some implementations where the parallelism deviation is sufficiently small, a small-angle approximation can be used. As will be obvious to those skilled in the art, under a small-angle approximation (when treated in radians), ε ij,p =(x i -x j ) / (2n s ·f1) and ε ij,r =(y i –y j ) / (2n s ·f1).

[0285] According to some implementations, determining the coordinates of the light spot may include: calculating the associated uncertainty, and based thereon, calculating the uncertainty of the parallelism deviation between the pair of internal facets.

[0286] In some embodiments where the internal facets are not examined one at a time (e.g., all internal facets are examined simultaneously), such that the coordinates of the determined returning beam (e.g., the center point of the spot formed by the returning beam on the image sensor) are generally (at least without additional data) not attributable to one of the internal facets, in stage 970, the average radial deviation of parallelism (i.e., the average deviation magnitude) and / or the maximum radial deviation of parallelism (i.e., the deviation magnitude) are calculated. According to some embodiments, the angular deviation between pairs of returning beams can be calculated first. More specifically, this can be achieved by using a relational expression... and n s sin(2ε′) ij )=sin(δ′ ij To obtain the average radial deviation of parallelism, in order to calculate... Here, δ′ lm ε′ is the magnitude of the angular deviation between the beam causing the l-th spot and the beam causing the m-th spot. lmIt is the magnitude of the deviation (i.e., radial deviation) between the inner facet that causes the beam of the l-th spot to be reflected away and the inner facet that causes the beam of the m-th spot to be reflected away. M is the number of (different) pairs of inner facets. This can be calculated by max{ε} lm} l，m＞1 To obtain the maximum radial deviation of parallelism.

[0287] According to some embodiments, in order to eliminate the need to distinguish between the returning beam and light directly reflected off the first surface of the optical element, the first surface of the optical element may be coated with an anti-reflective coating. Additionally or alternatively, according to some embodiments, the incident beam may be slightly tilted at an angle Δ′ relative to the normal of the first surface of the optical element. As explained above in the description of system 100, |Δ′| is chosen to be sufficiently large to ensure that the returning beam can be distinguished from light directly reflected off the first surface of the optical element. According to some embodiments, 0.3° ≤ |Δ′| ≤ 0.5°, 0.2° ≤ |Δ′| ≤ 0.7°, or even 0.1° ≤ |Δ′| ≤ 1°. Each possibility corresponds to a different embodiment.

[0288] According to some embodiments, particularly those in which the first surface of the sample and / or the first surface of the optical element is not sufficiently polished and / or cannot be aligned with sufficient precision to eliminate or at least mitigate dispersion, as detailed above in the description of system 100, the sample has approximately the same refractive index as the substrate (e.g., greater than n). s -0.02 and less than n s A shape-adjustable interface (+0.02) can be positioned between the optical element and the sample.

[0289] According to some embodiments, an optical-based method is provided for measuring the internal facets of a sample. This method can be used to verify the parallelism between the internal facets of a sample. Figure 10 A flowchart of such a method (optics-based method 1000) according to some embodiments is presented. Method 1000 may include:

[0290] - Stage 1010, wherein a sample to be inspected (e.g., sample 60) is provided. The sample includes samples with a refractive index n. s The light-transmitting substrate has two or more nominally parallel internal facets (e.g., internal facet 64) embedded in it. Each internal facet is oriented approximately orthogonally to an external and flat first surface and an external and flat second surface of the sample.

[0291] - Stage 1020, wherein a first optical element (FOE; e.g., FOE 602 or FOE 702) and a second optical element (SOE; e.g., SOE 682 or SOE 782) are provided. Each of the FOE and SOE has approximately equal to n. s "(For example, greater than n)" s -0.02 and less than n s The corresponding refractive index is ″+0.02. The FOE includes an external and flat first surface and an external and flat second surface, the second surface being opposite to the first surface of the FOE and inclined at an acute angle relative to the first surface. The SOE includes an external and flat first surface and an external and flat second surface, the second surface being opposite to the first surface of the SOE and inclined at approximately (the second surface of the FOE relative to the first surface of the FOE) angle.

[0292] - Stage 1030, wherein the sample, FOE and SOE are positioned such that the sample is disposed between FOE and SOE, wherein the second surface of FOE and the second surface of SOE are adjacent to the first surface and the second surface of the sample, respectively.

[0293] - Stage 1040, wherein multiple incident beams are projected onto the first surface of the FOE approximately perpendicular to it (e.g., within 1°, 1.5° or even 2° of perpendicular incidence).

[0294] - Stage 1050, wherein a second plurality of beams (also referred to as “outgoing beams”) are obtained by passing the incident beam through the FOE, transmitting it into the sample, reflecting it once from the internal facet, transmitting it into the SOE, and exiting the SOE (e.g., refracting it out).

[0295] - Stage 1060, wherein a second plurality of light beams are sensed (i.e., measured, for example, using a light sensing component 624 or an image sensor 724).

[0296] - Stage 1070, wherein, based on the sensed data, at least one parallelism deviation between at least some internal facets is calculated.

[0297] Method 1000 corresponds to a specific implementation of method 800. Method 1000 can be used to verify the parallelism between the internal facets of a sample (e.g., sample 60). As described above... Figures 6A to 7 As taught in the description, method 1000 can be implemented using an optical-based system (e.g., system 600 and system 700 or any of similar systems).

[0298] According to some implementations in which each of the beams emitted from the SOE can be traced back to a specific internal facet in the sample (e.g., by examining the internal facets one at a time), the relation tan(δ″) can be used. ij,p )=(x′ i -x′ j ) / f2 and n s "·sin(2ε") ij,p )=sin(δ″ ij,p To calculate the pitch deviation ε″ between the i-th and j-th inner planes. ij,p Similarly, the relation tan(δ″) can be used. ij,r )=(y′ i -y′ j ) / f1 and n s "·sin(2ε") ij,r )=sin(δ″ ij,r To calculate the roll deviation ε″ between the i-th and j-th inner facets. ij,r f2 is the focal length of the focusing lens or focusing lens assembly used to focus the emitted light beam onto the photosensitive component used to sense the emitted light beam. x′ i and x′ j These are the x-coordinates of the i-th and j-th emitted beams, respectively (e.g., the horizontal coordinates of the spots formed on the image sensor by the i-th and j-th emitted beams). y′ i and y′ j These are the y-coordinates of the i-th and j-th emitted beams, respectively (e.g., the vertical coordinates of the spots formed on the image sensor by the i-th and j-th emitted beams). (Here, it is implicitly assumed that the coordinate system decouples the tilt in pitch and the tilt in roll, as illustrated in the description of method 900 above.)

[0299] According to some implementations, determining the coordinates of the light spot may include: calculating the associated uncertainty, and based thereon, calculating the uncertainty of the parallelism deviation between the pair of internal facets.

[0300] In some embodiments where the coordinates of the determined outgoing beam (e.g., the center point of the spot formed on the image sensor) are not typically attributed to one of the internal facets, rather than being examined one at a time, in stage 1070, the average radial deviation of parallelism and / or the maximum radial deviation of parallelism are calculated. According to some embodiments, the angular deviation between pairs of outgoing beams can be calculated first. More specifically, this can be achieved by using a relational expression... and n s "·sin(2ε″′ ij )=sin(δ″′ ijTo obtain the average radial deviation of parallelism, in order to calculate Here, δ″′ lm It is the magnitude of the angular deviation between the beam causing the l-th spot and the beam causing the m-th spot. δ″′ lm ε″ is the magnitude of the deviation (i.e., radial deviation) between the inner facets from which the beam reflected from the l-th spot and the inner facets from which the beam reflected from the m-th spot. M′ is the number of (different) pairs of inner facets. This can be calculated by max{ε″′. lm} l，m＞1 To obtain the maximum radial deviation of parallelism.

[0301] According to some embodiments, particularly those in which the first and second surfaces of the sample and / or the second surfaces of the FOE and SOE are not sufficiently polished and / or cannot be aligned with adequate precision, in order to eliminate or at least mitigate dispersion, a substrate having approximately the same dimensions as (the sample) (e.g., greater than n) can be used. s -0.02 and less than n s A shape-plastic interface with a refractive index of +0.02 is positioned between the FOE and the sample, and between the SOE and the sample, as detailed in the description of system 600 above.

[0302] As used herein, the terms “measurement” and “sensing” are used interchangeably. Similarly, the terms “sensed data” and “measured data” (or “measured data”) are used interchangeably.

[0303] It should be understood that certain features of this disclosure described in the context of a single implementation for clarity may also be provided in combination in a single implementation. Conversely, various features of this disclosure described in the context of a single implementation for brevity may also be provided individually or in any suitable sub-combination or as suitably provided in any other described implementation of this disclosure. Features described in the context of an implementation should not be considered essential features of that implementation unless expressly specified otherwise.

[0304] Although the stages of a method according to some embodiments may be described in a specific order, the method of this disclosure may include some or all of the described stages performed and / or occurring in a different order. The method of this disclosure may include several or all of the described stages. No particular stage in the disclosed method should be considered a necessary stage of the method unless expressly specified otherwise.

[0305] Although this disclosure has been described in conjunction with specific embodiments thereof, it will be apparent to those skilled in the art that many alternatives, modifications, and variations may be possible. Therefore, this disclosure encompasses all such alternatives, modifications, and variations that fall within the scope of the appended claims. It should be understood that the application of this disclosure is not necessarily limited to the details of the construction and arrangement of the components and / or methods set forth herein. Other embodiments may be practiced, and embodiments may be implemented in various ways.

[0306] The wording and terminology used herein are for descriptive purposes and should not be construed as limiting. Any references or designations made herein should not be interpreted as an admission that such references can be used as prior art to this disclosure. Section headings used herein are for ease of understanding and should not be construed as necessarily limiting.

Claims

1. An optical-based system for measuring a sample having a refractive index of n s The system includes a substrate and two or more internal facets embedded in the substrate, nominally parallel and perpendicular to an external and flat first surface of the sample; the system includes a first optical element and an optical device, the optical device including a light source, an optical apparatus and a photosensing component. in, The first optical element has an n s The refractive index and includes an external and flat first surface and an external and flat second surface, the second surface being opposite to the first surface of the first optical element and inclined at an acute first angle relative to the first surface of the first optical element; The optical device is configured such that the sample and / or the first optical element are positioned such that the second surface of the first optical element is adjacent to the first surface of the sample, and when positioned in this way, a first plurality of light beams generated by the light source will illuminate the first surface of the first optical element perpendicularly to the first surface of the first optical element. The first optical element is further configured to focus a second plurality of beams emitted from the sample after passing through the first optical element, being transmitted into the sample, and being reflected once from the internal facet, onto the photosensitive component, thereby enabling the measurement of the angular deviation between the beams in the second plurality of beams; and The angular deviation between the beams in the second plurality of beams indicates the parallelism deviation between the internal facets.

2. The system according to claim 1, wherein, The optical device includes a collimating lens or collimating lens assembly configured to collimate the light beam generated by the light source, thereby preparing the first plurality of light beams, and / or The optical device includes a focusing lens or focusing lens assembly, which is configured to focus a beam from the second plurality of beams onto the photosensitive component.

3. The system according to claim 2, wherein, The light source is a laser source.

4. The system according to claim 1, wherein, The light-sensing component includes an image sensor configured to sense the second plurality of light beams; and / or The light-sensing component includes an eyepiece assembly.

5. The system according to claim 1, wherein, The optical device is configured to position the sample and the first optical element such that a first region on a first surface of the sample is in complete contact with a second surface of the first optical element, the first region being defined by a portion of the sample including the internal facet.

6. The system according to claim 1, wherein, The sample is a one-dimensional or two-dimensional reflective waveguide.

7. The system according to claim 1, wherein, The first optical element is a prism.

8. The system according to claim 1, wherein, The optical device also includes a slit or aperture-like optical mask and / or multiple shutters that can be translated, the optical mask and / or the multiple shutters being configured to allow the internal facets to be inspected one at a time.

9. The system according to claim 4, wherein, The sensed data includes the measured intensity of the pixels that constitute the light spots caused by the beams in the second plurality of beams on the image sensor.

10. The system of claim 9, further comprising a calculation module configured to calculate the parallelism deviation between the internal facets based on the sensed data.

11. The system according to claim 10, wherein, As part of calculating the parallelism deviation, the calculation module is configured to calculate the angular deviation between the beams in the second plurality of beams based on the sensed data.

12. The system according to claim 10, wherein, The calculation module is configured to calculate parameters. and / or ,in, equal And, equal or ,and , It is a set of two-dimensional vectors specifying the positions of the i-th and j-th light spots on the image sensor, where N is the number of the internal facets. And f is the focal length of the focusing lens or focusing lens assembly configured to focus the beam of the second plurality of beams onto the image sensor.

13. The system according to claim 10, wherein, The optical device further includes a slit or aperture-like optical mask and / or multiple shutters that can be translated, the optical mask and / or the multiple shutters being configured to allow the internal facets to be inspected one at a time, and wherein the computing module is configured to calculate the parallelism deviation between pairs of internal facets in the two or more internal facets.

14. The system according to claim 13, wherein, Calculating the parallelism deviation between the paired internal facets includes: calculating the pitch deviation between the internal facets in each pair of internal facets. and / or roll deviation Where indices i and j involve different inner plane pairs, and and These are the pitch deviation and roll deviation between the i-th and j-th internal small planes, respectively.

15. The system according to claim 14, wherein, Separate Path and To calculate the and stated ,in, The pitch deviation between the i-th beam in the second plurality of beams caused by reflection from the i-th internal plane and the j-th beam in the second plurality of beams caused by reflection from the j-th internal plane is... It is the roll deviation between the i-th beam and the j-th beam in the second plurality of beams. It is a set of two-dimensional vectors that specify the position of the spot on the image sensor caused by the beam of the second plurality of beams, the index k denotes the beam, N is the number of the internal facets, and f is the focal length of the focusing lens or focusing lens assembly configured to focus the beam of the second plurality of beams on the image sensor.

16. The system according to claim 1, wherein, The optical device is configured to position the sample and / or the first optical element such that a first region on a first surface of the sample is in complete contact with a second surface of the first optical element, the first region being defined by a portion of the sample including the internal facet.

17. The system according to claim 1, wherein, The first surface of the first optical element is coated with an anti-reflective coating.

18. The system according to claim 1, wherein, The optical device includes an autocollimator configured to generate the first plurality of light beams and focus one of the second plurality of light beams onto the photosensitive element.

19. The system according to any one of claims 1 to 18, wherein, The second plurality of light beams includes light beams that pass through the first surface of the sample and light beams that return from the sample via the first optical element.

20. The system according to claim 19, wherein, The sample includes an external and flat second surface opposite to a first surface of the sample, and wherein the returning light beam is reflected from the second surface of the sample before exiting the sample via the first surface.

21. The system according to claim 20, wherein, The inner plane of the sample is orthogonal to the first surface of the sample, and the second surface of the sample is parallel to the first surface of the sample.

22. The system according to claim 21, wherein, The adjacent internal facets of the sample are spaced apart at regular intervals, and the first tilt angle is equal to Where d1 is the distance between the first surface and the second surface of the sample, and d2 is the distance between adjacent internal facets of the sample.

23. The system according to any one of claims 1 to 15, wherein, The sample includes an external and flat second surface opposite to a first surface of the sample, and wherein the second plurality of light beams includes light beams emitted from the sample via the second surface of the sample.

24. The system of claim 23, further comprising a second optical element having a number equal to n s The refractive index and includes an external and flat first surface and an external and flat second surface, the second surface being opposite to the first surface of the second optical element and inclined at an acute second angle relative to the first surface of the second optical element; and in, The optical device is additionally configured to position the sample and / or the second optical element such that the second surface of the second optical element is adjacent to the second surface of the sample.

25. The system according to claim 24, wherein, The second plurality of light beams includes light beams that exit from the sample via a second surface of the sample and are transmitted into the second optical element, and then exit from the second optical element via a first surface of the second optical element.

26. The system according to claim 25, wherein, The optical device is further configured to position the sample and / or the second optical element such that a first region on a first surface of the sample is in complete contact with a second surface of the first optical element, and a second region of the sample opposite to the first region is in complete contact with a second surface of the second optical element, the first region and the second region being defined by a portion of the sample including the internal facet.

27. The system according to claim 26, wherein, The inner plane of the sample is orthogonal to the first surface of the sample, and the second surface of the sample is parallel to the first surface of the sample.

28. The system according to claim 27, wherein, The second tilt angle is equal to the first tilt angle, such that each of the second plurality of beams exits from the second optical element perpendicularly to the first surface of the second optical element.

29. The system according to claim 28, wherein, The adjacent internal facets of the sample are spaced apart at regular intervals, and each of the first tilt angle and the second tilt angle is equal to Where d1 is the distance between the first surface and the second surface of the sample, and d2 is the distance between adjacent internal facets of the sample.

30. The system according to claim 24, wherein, The second optical element is a prism.

31. The system according to claim 24, wherein, The first surface of the first optical element and the first surface of the second optical element are coated with an anti-reflective coating.

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