Optical verification of parallelism between internal facets

Abstract

This document discloses a method for verifying the parallelism of internal facets of a sample. The method includes: (i) providing a sample comprising a transparent substrate and internal facets that are nominally parallel and at an angle μ relative to a flat surface of the sample. nom (ii) providing a prism having substantially the same refractive index as the substrate and comprising a flat first surface and a flat second surface opposite to and relative to the first surface at a substantially angle μ. nom (iii) Tilting the sample and the prism such that the surface of the sample is parallel to and adjacent to the second surface of the prism; (iv) Projecting an incident beam onto the first surface of the prism substantially perpendicular to the first surface; (v) Sensing the light returning from the prism after reflection from the inner facets; and (vi) Calculating the parallelism deviation between the inner facets.

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 comprising one or more internal facets. More specifically, but not exclusively, according to some embodiments of this disclosure, aspects of this disclosure relate to optical-based methods and systems for measuring samples comprising a plurality of nominally parallel internal facets.

[0004] Reflective waveguides are used in various displays, including 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 (via 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 (without 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 production stages 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 and in their later production stages. 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 of internal facets of a sample. The method includes the following stages:

[0008] - Provide a sample comprising a transparent substrate and two or more internal facets. The substrate has a refractive index n. s The internal facets are embedded within the substrate. Each internal facet is positioned relative to the outer, flat surface of the sample at a nominal acute angle μ. nom Nominal ground tilt.

[0009] - Provides a refractive index approximately equal to n s An optical element. The optical element includes an external, flat first surface and an external, flat second surface. The second surface of the optical element is opposite to the first surface of the optical element and is positioned relative to the first surface at approximately a nominal angle μ. nom tilt.

[0010] - Position the sample and optical element such that the second surface of the optical element is parallel to and adjacent to the surface of the sample.

[0011] - Project multiple incident light beams onto the first surface approximately perpendicular to the first surface of the optical element.

[0012] - Multiple return beams are obtained after the incident beam passes through the optical element, is transmitted into the sample and reflected away from the internal plane, passes through the optical element again and exits the optical element via the first surface of the optical element (e.g., refracted out).

[0013] -Sense the return beam.

[0014] - Based on the sensed data, calculate at least one parallelism deviation between at least some of the internal facets.

[0015] According to some embodiments of this method, the optical element has an n-value s The refractive index.

[0016] According to some embodiments of the method, the incident light beam is projected vertically onto the first surface of the optical element.

[0017] According to some embodiments of the method, the stage of calculating the parallelism deviation between the internal facets includes: calculating the angular deviation between the returning beams.

[0018] According to some embodiments of the method, the incident beam constitutes a complementary portion 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] According to some embodiments of this method, the optical element is a 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 the method, the second surface of the optical element is at an angle μ relative to the first surface of the optical element. nom +Δ tilt. |Δ| is greater than approximately 0.1° and less than approximately 1°.

[0025] According to some embodiments of the method, the second surface of the optical element is positioned relative to the first surface of the optical element at a nominal angle μ. nom tilt.

[0026] According to some embodiments of the method, the first surface of the optical element is coated with an anti-reflective coating.

[0027] According to some embodiments of the method, the method further includes: applying a liquid having the same refractive index as the substrate, such that the sample, the liquid, and the prism form a continuous medium.

[0028] According to some implementations of this method, an image sensor is used to sense the returning beam.

[0029] According to some embodiments of the method, the sensing data corresponding to each returning beam includes the measured intensity of the pixels that constitute the light spot formed by the returning beam on the image sensor.

[0030] According to some implementations of this method, an autocollimator is used to generate the incident beam and focus the returning beam.

[0031] According to some embodiments of this method, the stage of sensing the returning beam includes: viewing the returning beam through an eyepiece. The returning beam appears as a spot on the scale lines of the eyepiece.

[0032] 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 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.

[0033] According to some implementations of the method, the incident beam is continuously projected onto each internal facet.

[0034] According to some embodiments of the method, continuous projection is achieved using a slit or aperture optical mask that can be translated and / or multiple shutters.

[0035] According to some implementations of this method, when calculating the parallelism deviation, the parallelism deviation between pairs of internal facets from multiple internal facets is calculated.

[0036] According to some implementations of the method, the paired internal facets include a pair of adjacent internal facets.

[0037] According to some embodiments of this method, calculating the parallelism deviation between pairs of internal facets includes: calculating the 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 refer to different pairs of internal planes. 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 returning beam caused by reflection from the i-th internal facet and the j-th returning beam caused by reflection from the j-th internal facet. ij，r It is the roll deviation between the i-th returning beam and the j-th returning beam. This is a set of two-dimensional vectors specifying the position of the spot caused by the returning beam on the image sensor or relative to the scale lines of the eyepiece. Index k marks 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 the returning beam onto the image sensor or eyepiece.

[0038] 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 -nmin{x i}i ) / (2n s •f) and / or the maximum roll deviation between the internal facets (i.e., the range of roll deviation). This is a set of two-dimensional vectors specifying the position (e.g., center point) of the spot caused by the returning beam 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 returning beam onto the image sensor or eyepiece.

[0039] According to some embodiments of this method, the sample is a reflecting waveguide, and the first surface and the second surface of the sample correspond to the main surface of the waveguide. According to some such embodiments, the nominal angle μ... nom Less than 45°.

[0040] According to one aspect of some embodiments, an optical-based system for measuring a sample having a refractive index of n is provided. s The substrate and two or more internal facets, which are embedded in the substrate and relative to the external and flat surface of the sample at a nominal acute angle μ. nom Nominal orientation. The system includes a light-transmitting optical element and an optical device including a light source and a light-sensing component. The optical element has approximately equal to n. s The refractive index is defined by the optical element and includes an external, flat first surface and an external, flat second surface. The first surface and the second surface of the optical element are opposite to each other and define an angle approximately equal to the nominal angle μ between them. nomThe tilt angle. The optical device is configured to position the sample and / or optical element such that (i) the second surface of the optical element is parallel to and adjacent to the surface of the sample, and (ii) when so positioned, a light beam generated by the light source is incident on the first surface of the optical element approximately perpendicular to it; the optical device is also configured to focus the returned light beam onto a photosensitive element so that the angular deviation between the returned light beams can be determined. The returned light beam is obtained after the incident light beam passes through the optical element, is transmitted into the sample and reflected away from the internal facets, passes through the optical element again and exits the optical element via the first surface of the optical element (e.g., refracted). Therefore, the angular deviation indicates the deviation in parallelism between the internal facets.

[0041] According to some implementations of the system, the optical element has an n-value. s The refractive index.

[0042] According to some implementations of the system, the incident light beam is projected perpendicularly onto the first surface of the optical element.

[0043] 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 an incident light beam.

[0044] According to some implementations of this system, the light source is a monochromatic light source.

[0045] According to some implementations of this system, the light source is a laser light source.

[0046] According to some embodiments of the system, the optical device includes a focusing lens or focusing lens assembly configured to focus an outgoing light beam onto a photosensing component. According to some embodiments, for example, in which the optical device includes an autocollimator, the focusing lens or focusing lens assembly is a collimating lens or collimating lens assembly and may be included within the autocollimator.

[0047] According to some embodiments of the system, the second surface of the optical element is relative to the first surface of the optical element at a distance equal to μ. nom The angle of inclination is +Δ. |Δ| is greater than approximately 0.1° and less than approximately 1°.

[0048] According to some embodiments of the system, the second surface of the optical element is positioned relative to the first surface of the optical element at a nominal angle μ. nom tilt.

[0049] According to some embodiments of the system, the first surface of the optical element is coated with an anti-reflective coating.

[0050] According to some embodiments of the system, the optical device includes an orientation base structure configured to orient a sample.

[0051] According to some implementations of the system, the orientation base structure includes an elevation angle meter and a roll angle meter.

[0052] According to some implementations of the system, the directional foundation structure also includes a tilting platform, which tilts at an angle approximately equal to the nominal angle μ. nom The tilt angle is tilted. The tilting platform is configured to be mounted on the goniometer and the sample is placed on the tilting platform.

[0053] According to some implementations of the system, the sample is shaped as a thin plate or an elongated box.

[0054] According to some implementations of the system, the sample is a one-dimensional or two-dimensional reflective waveguide.

[0055] According to some embodiments of the system, the optical device also includes an autocollimator, which includes a light source and optionally includes a light-sensing component.

[0056] According to some embodiments of the system, the light-sensing component includes an image sensor configured to sense the return beam of light.

[0057] According to some implementations of the system, the light sensing component is or includes a camera device.

[0058] According to some embodiments of the system, the light sensing component includes an eyepiece assembly that includes scale markings.

[0059] According to some embodiments of the system, the optical device also includes a slit or aperture screen and / or multiple shutters that can be translated, the screen and / or multiple shutters being configured to allow for the inspection (probing) of the internal facets one at a time.

[0060] According to some embodiments of the system, the system also includes a calculation module configured to calculate the parallelism deviation between the internal facets based on sensing data of the returned beam obtained by the image sensor.

[0061] According to some implementations of the system, the sensing data associated with each returning beam includes the measured intensity of the pixels that constitute the corresponding light spot formed by the returning beam on the image sensor.

[0062] According to some implementations of the system, the calculation module is configured to calculate ε avg and / or ε max This is part of the calculation of the parallelism deviation between the internal facets. ε avg equal εmax Equal to max{ε ij} i，j＞i or

[0063] Here, is a set of two-dimensional vectors specifying the positions of the i-th and j-th light spots on the image sensor. 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 light beam onto the image sensor.

[0064] According to some implementations of the system, the optical device further includes a slit or aperture-like optical mask that can be translated and / or multiple shutters, and the computing module is configured to calculate the parallelism deviation between pairs of internal facets in a plurality of internal facets.

[0065] According to some implementations of the system, a pair of internal facets includes a pair of adjacent internal facets.

[0066] According to some implementations of the system, the calculation module is configured to calculate the pitch deviation and / or roll deviation between the pairs of internal facets as part of the calculation of the parallelism deviation between the pairs of internal facets.

[0067] According to some implementations of the system, calculating the parallelism deviation between pairs of internal facets includes: calculating the 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 refer to different pairs of internal planes. 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，pδ is the pitch deviation between the i-th returning beam caused by reflection from the i-th internal facet and the j-th returning beam caused by reflection from the j-th internal facet. ij，r It is the roll deviation between the i-th returning beam and the j-th returning beam. This is a set of two-dimensional vectors specifying the position of the spot on the image sensor caused by the returning beam. 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 the returning beam onto the image sensor.

[0068] 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 •f) and / or the maximum roll deviation between the internal facets (i.e., the range of roll deviation). This is a set of two-dimensional vectors specifying the position (e.g., center point) of the spot on the image sensor caused by the returning beam. 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 returning beam onto the image sensor.

[0069] According to some embodiments of the system, the sample is a reflecting waveguide, and the first surface and the second surface of the sample correspond to the main surface of the waveguide. According to some such embodiments, the nominal angle μ... nom Less than 45°.

[0070] 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 all, some, or none of the listed advantages.

[0071] Unless otherwise specified, 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 definition, 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”.

[0072] 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.

[0073] Embodiments of this disclosure may include devices for performing the operations described herein. These devices may be specifically constructed for a desired purpose or may include general-purpose computers selectively activated or reconfigured by computer programs stored in a computer. Such computer programs may be stored in computer-readable storage media, 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.

[0074] 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 programs based on the teachings 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, the implementations 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.

[0075] 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

[0076] 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.

[0077] In the attached diagram:

[0078] 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.

[0079] Figure 1B It is based on some implementation methods Figure 1A A cross-sectional view of a portion of the sample;

[0080] Figure 1C It is based on some implementation methods Figure 1A A three-dimensional view of the end of the sample;

[0081] Figure 1D The diagram schematically depicts the operation during sample inspection according to some embodiments. Figure 1A The system;

[0082] Figure 1E yes Figure 1D A magnified view of a portion;

[0083] Figure 2A The illustration schematically depicts the results obtained as part of sample inspection according to some embodiments. Figure 1A The light spot on the photosensitive surface of the system's image sensor;

[0084] Figure 2BThe illustration schematically depicts the results obtained as part of sample inspection according to some embodiments. Figure 1A The light spot on the photosensitive surface of the system's image sensor;

[0085] Figure 3 An optical-based system for measuring the internal facets of a sample is schematically depicted, which corresponds to Figure 1A Specific implementation methods of the system;

[0086] Figure 4 The illustration schematically depicts the results obtained as part of sample inspection according to some embodiments. Figure 3 The light spot on the digital display associated with the system's autocollimator;

[0087] Figure 5 A schematic depiction of... Figure 1A The specific implementation of the system corresponds to some components of an optical-based system for measuring the internal facets of a sample, and the sample that will be examined using the system;

[0088] Figure 6 A flowchart of an optical-based method for measuring the internal facets of a sample, according to some embodiments, is presented; and

[0089] Figure 7A and Figure 7B Laboratory results obtained using the disclosed methods and systems according to some implementations are presented. Detailed Implementation

[0090] 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.

[0091] 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.

[0092] As used herein, the term "about" can be used to specify a quantity or parameter (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 "about equal to" and "equal to about" also cover exact equality.

[0093] As used herein, the terms “substantially” and “about” may be used interchangeably according to some implementations.

[0094] 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 object being depicted 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".

[0095] In the accompanying drawings, optional elements and optional stages (in the flowchart) are depicted by dashed lines.

[0096] Throughout the description, vectors are represented by bold lowercase upright letters (e.g., v).

[0097] 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 quantities. 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 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, ns The symbols ε and f (and the symbols “μ”, “σ”, and “Δ” for angles) should not be considered limited to the specific implementations in which they are first introduced in the text. In particular, the parameters ε, δ, and n are considered within the context of one implementation. s The values ​​of f (and parameters μ, σ and Δ) and u (components), the range of values ​​and / or the constraints on the values ​​are not necessarily carried over to another implementation.

[0098] 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".

[0099] As used in this article, an object may be said to "nominally" represent a property (i.e., characterized by that property) when the object is designed and manufactured to represent a property, but in reality, that property may not be perfectly represented due to manufacturing tolerances, such as the angle of inclination between the flat surfaces of a sample.

[0100] system

[0101] According to one aspect of some embodiments, an optical-based system for measuring internal facets in a sample is provided. Figure 1A An optically based system 100, according to some embodiments, is schematically depicted. The optically 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.)

[0102] Sample 10 includes a light-transmitting substrate 12 and two or more internal facets 14 embedded within the substrate (i.e., embedded in the substrate). Sample 10 includes an external first surface 16a (also referred to as the "sample first surface"). The sample first surface 16a may be flat. According to some embodiments, each internal facet 14 may be a thin semi-reflective or reflective layer embedded within the substrate 12. According to some embodiments, one or more internal facets 14 may be a thin film or a partial reflector. According to some embodiments, one or more internal facets may be or include a glass layer and / or a dielectric coating. According to some embodiments, the substrate 12 may be a one-dimensional or two-dimensional reflective waveguide (also referred to as a "geometric waveguide"), in which case sample 10 may include an external and flat second surface 16b (also referred to as the "sample second surface") opposite and parallel to the sample first surface 16a. According to some embodiments, where sample 10 is a reflective waveguide, the sample first surface 16a and sample second surface 16b may correspond to the main surface of the waveguide. According to some embodiments, the substrate 12 may be made of glass, crystal, or a transparent polymer.

[0103] The output portion 18 of sample 10 corresponds to the portion (e.g., segment) where the internal facet 14 of substrate 12 is located (while the portion of the substrate complementary to the output portion may not have any internal facet 14). See also... Figure 1B , Figure 1B An enlarged view of the output portion 18 according to some embodiments is provided. This is intended as a non-limiting example for ease of description. 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. The second inner facet 14b is arranged 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).

[0104] Also refer to Figure 1C , Figure 1C A perspective view of the end portion 15 of a sample 10 according to some embodiments is provided, which includes a second inner facet 14b and a third inner facet 14c. The nominal orientations of the second inner facet 14b and the third inner facet 14c are shown by plane B and plane C (delineated by dashed lines), respectively. (Both plane B and plane C are parallel to the xy plane.)

[0105] 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 relative to the first surface 16a of the sample at a nominal angle μ. nom The nominal angle is tilted. However, in practice, each internal facet 14 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 14a, the second internal facet 14b, and the third internal facet 14c are oriented relative to the first surface 16a of the sample at a first actual angle μ1, a second actual angle μ2, and a third actual angle μ3, respectively. It should be noted that due to manufacturing defects, the actual angles μ1, μ2, and μ3 may differ slightly. i (i = 1, 2, 3) may be each other and / or with the nominal angle μ nom The differences lie not only in their magnitudes but also in their respective opposing planes. For example, if the nominal angle is directed toward a first plane parallel to the zx plane, then μ1 can be directed toward a second plane inclined relative to the first plane. Similarly, μ2 can be directed toward a third plane inclined relative to the first and / or second planes. In other words, μ1 is represented by unit vectors a, b, and c, respectively, 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, where it is assumed that there are no manufacturing defects. Here, This represents the unit vector along the z-axis.

[0106] 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.

[0107] b, indicated on plane B x and b y These are the x and y components of b, respectively. The second internal small plane 14b is shown as tilted relative to plane B in both pitch and roll, as represented by b, respectively. x and b y This indicates that each of them is non-zero. c is indicated on plane C. x and c y These are the x and y components of c, respectively. The third internal plane 14c is shown as tilted relative to plane C in both pitch and roll, as represented by c, respectively. x and c y This indicates that each is non-zero. Furthermore, the second inner plane 14b and the third inner plane 14c are shown to differ from each other in both pitch and roll (i.e., in...). Figure 1CIn the middle, c x >b x and c y >b y ).

[0108] 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 output portion 18 defines an output region 13 on the first sample surface 16a. According to some embodiments, the sample 10 can be configured such that light propagating in the direction of the second end 11b will exit the sample 10 through the output region 13 after being reflected by the internal facet 14.

[0109] 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 or constitute 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 or include an eyepiece assembly configured for visually determining (i.e., by eye) deviations 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.

[0110] Optical element 102 includes a substrate 132, which forms the body of optical element 102 and is made of a material having approximately the same refractive index as substrate 12 (e.g., within ±0.02 of the refractive index value). Optical element 102 also includes an outer first surface 134a (e.g., the outer first surface of substrate 132; also referred to as the "optical element first surface") and an outer second surface 134b (e.g., the outer second surface of substrate 132; also referred to as the "optical element second surface"). According to some embodiments, and as... Figure 1AAs depicted, the first surface 134a and the second surface 134b of the optical element are flat. According to some embodiments, the optical element 102 is a prism. According to some such embodiments, the prism may be a triangular prism.

[0111] like Figure 1C and Figure 1D As shown and described in detail below, optical element 102 is configured such that at least some of the light incident on the first surface 134a of optical element and at an incident angle sufficiently close to 0° exits optical element 102 via (i.e., through) the second surface 134b of optical element. More specifically, optical element 102 is configured such that at least some of the light incident perpendicularly on the first surface 134a of optical element and thus transmitted into optical element 102 will travel through optical element 102 at an angle approximately equal to the nominal tilt angle μ. nom The incident angle illuminates the second surface 134b of the optical element.

[0112] According to some embodiments, the second surface 134b of the optical element may be tilted relative to the first surface 134a of the optical element at a nominal tilt angle μ. nom Inclined (i.e., σ = μ) nom Alternatively, according to some implementations, and as described in detail below, σ = μ nom +Δ, where 0.3°≤|Δ|≤0.5°, 0.2°≤|Δ|≤0.7°, or even 0.1°≤|Δ|≤1°. Each possibility corresponds to a separate implementation.

[0113] The ICA 112 is configured to output a collimated beam (such as...). Figure 1C and Figure 1DAs shown, the collimated beam is generated by a light source 122 and optionally manipulated (e.g., collimated) by an optical device 128 (in embodiments including the 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) may be configured such that the beam output from the ICA 112 is perpendicular (or at least substantially perpendicular) to the first surface 134a of the optical element. According to some embodiments, the light source 122 may be configured to generate a monochromatic beam (and the beam output from the ICA 112 is monochromatic). According to some embodiments, the light source 122 may be a laser source (and the beam output from the ICA 112 is a laser beam). According to some embodiments where the light source 122 is a laser source, the ICA 112 may 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, for example when the sample 10 is a one-dimensional reflecting waveguide, the diameter of the expanded laser beam (e.g., the longest diameter when the cross-section of the expanded laser beam defines an ellipse) may be approximately equal to the longitudinal dimension of the output region 13. According to some embodiments, for example when the sample 10 is a two-dimensional reflecting waveguide, the cross-sectional area of ​​the expanded laser beam may have a size approximately equal to the cross-sectional area of ​​the output region 13.

[0114] According to some embodiments, the light source 122, the photosensing component 124, and at least some optical devices 128 may include an autocollimator or components including 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. According to some embodiments, the light source 122 and at least some optical devices 128 may constitute an autocollimator or components constituting an autocollimator, which are attached to an imaging device constituted by the photosensing component 124.

[0115] According to some embodiments, the optical device 128 may also include a slit or aperture-like optical mask (not shown; for example, the slit-like optical mask of FIG. 2), such an optical mask being configured to control the incident (i.e., irradiation, impact) position of a light beam (e.g., a laser beam) on the first surface 134a of the optical element, thereby allowing individual inspection of each internal facet 14. Alternatively, according to some embodiments, the optical device 128 may also include a plurality of shutters, such that the plurality of shutters are configured to allow individual inspection of each internal facet 14.

[0116] 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 (of the optical element 102). According to some embodiments, the retaining base structure 114 can also be configured to orient the sample 10 such that the incident beam output from the ICA 112 will 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 orientation base structure in the form of an orientable stage assembly 138 (e.g., a biaxial stage).

[0117] 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 (e.g., relative to ICA 112). 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 arranged on top of the other. According to some such embodiments, the stage assembly 138 may include a tilting platform (e.g., Figure 5 The inclined platform depicted in the image; Figure 1A (Not shown in the image), the tilting platform is configured to (i) be positioned on top of one of the two goniometers and (ii) place sample 10 thereon. The tilt angle of the platform may be equal to or approximately equal to the nominal angle μ. nom In some such embodiments, the optical element 102 may be positioned on and supported by the sample 10. Alternatively, according to some embodiments, the retaining base 114 may include an oriented retaining gear (not shown) configured to retain and controllably orient the optical element 102. According to some embodiments, the retaining base 114 may be functionally associated with and configured to be controlled by the controller 108.

[0118] 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 being inspected by the system 100. Figure 1E Provided by the dashed line L Figure 1DA magnified view of a portion of the image. In operation, according to some embodiments, an extended incident beam, indicated by arrow 105, is projected onto the first surface 134a of the optical element (not all extended incident beams are numbered). The incident beam is collimated. In embodiments where the incident beam is multicolored, the incident beam is projected perpendicularly onto the first surface 134a of the optical element, while in embodiments where the incident beam is monochromatic, the incident beam may be projected perpendicularly onto the first surface 134a of the optical element or at least approximately perpendicular to the first surface 134a of the optical element (e.g., within 1°, 1.5°, or even 2° of perpendicular incidence).

[0119] An incident light beam (or at least a portion thereof) is transmitted through (i.e., via) 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., is transmitted) the second surface 134b of the optical element and the first surface 16a of the sample into the sample 10, and propagates from the first surface 16a of the sample towards the inner facet 14. The transmitted light beam is reflected away from the inner facet 14 and returns towards the first surface 16a of the sample.

[0120] 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.

[0121] The reflected beam exits from sample 10 via the first surface 16a and enters optical element 102 via the second surface 134b. The reflected beam travels from the second surface 134b to the first surface 134a and exits from optical element 102, thus generating multiple return beams: the first return beam, generated by the refraction of the first transmitted beam from optical element 102, is indicated by arrow 135a; the second return beam, generated by the refraction of the second transmitted beam from optical element 102, is indicated by arrow 135b; and the third return beam, generated by the refraction of the third transmitted beam from optical element 102, is indicated by arrow 135c. The propagation direction of the i-th (i = 1, 2, 3) return beam is tilted relative to the direction defined by the positive z-axis by a return angle ζ. iFor example, the propagation direction of the first returning beam (indicated by arrow 135a) is tilted by a return angle ζ1 relative to the normal of the first internal facet 14a. The returning beam propagates toward ICA 112 and is focused onto the photosensing component 124 by the optical device 128.

[0122] The light-sensing component 124 is configured to allow the angular deviation between a pair of returning beams focused on the light-sensing component to be obtained from its sensing data. For example, as follows: Figure 2A and Figure 2B As described in the description, the deviation of parallelism, or at least the magnitude of the deviation of parallelism, between the internal facets 14 can be inferred from the angular deviation.

[0123] According to where σ=μ nom In some implementations, the first surface 134a of the optical element may be coated with an anti-reflective coating such that at most a negligible portion of the incident light beam is reflected away from the first surface 134a of the optical element.

[0124] According to where σ=μ nom Some implementations of +Δ, for example in or even Furthermore, when the first surface 134a of the optical element is not coated with an anti-reflective coating, a portion of the incident beam is reflected by the first surface 134a of the optical element, as indicated by arrow 145. Arrow 145 is drawn as a dashed line to emphasize that the reflected portion exists only in some embodiments (i.e., the portion of the incident beam reflected away from the first surface 134a of the optical element), and particularly not (or at least negligible) in embodiments where the first surface 134a of the optical element is coated with an anti-reflective coating. The value of Δ can be chosen to ensure that the returned beam (indicated by arrows 135a, 135b, and 135c) is distinguishable from the reflected portion (indicated by arrow 145). 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 reflected portion of the incident light beam fall noticeably outside the cluster.

[0125] 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 optical element contacts the entire first surface 16a of sample, or contacts at least the entire output 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.

[0126] According to some embodiments, the second surface 134b of the optical element does not contact the first surface 16a of the sample. When the transmitted beam exits the optical element 102 via the second surface 134b, the space between the optical element 102 and the sample 10 (unless filled as described below and / or the incident beam is sufficiently monochromatic) may cause dispersion. 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).

[0127] Additionally or alternatively, according to some embodiments (not depicted in the figures), to avoid or mitigate dispersion, a refractive index-matched shape-compliant interface (not shown) 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-compliant interface may have a refractive index approximately the same as (e.g., within ±0.02) that of the substrate 12 (and the optical element 102). The shape-compliant interface may be a paste, liquid, or gel characterized by surface tension and / or adhesive properties to maintain its integrity and arrangement when confined in a narrow space. According to some embodiments, the shape-compliant interface may be a stretchable material. Thus, a light beam propagating through the optical element 102, the shape-compliant interface, and the sample 10 will substantially maintain its propagation direction as it enters the shape-compliant interface from the optical element 102 and from the shape-compliant interface into the sample 10.

[0128] Refer again Figure 1B and Figure 1C It is understandable that attempts to directly examine the internal facet 14 without using an "intermediate" (refractive index matching) optical element such as optical element 102 might require projecting an incident beam onto the first surface 16a of the sample at a sufficiently large angle of incidence (i.e., at the air-sample interface that would be formed in the absence of optical element 102) to ensure that light (or at least most of the light) reflected from one internal facet 14 (e.g., the second internal facet 14b) reappears via the first surface 16a of the sample without being reflected from the other internal facet (e.g., the first internal facet 14a). In turn, a large angle of incidence can result in a weak signal (also due to dispersion) and a low signal-to-noise ratio.

[0129] The disclosed system and method advantageously address this problem by controlling the incident angle (e.g., setting the incident angle to be equal to or close to zero) using refractive index-matching optics (e.g., optics 102 on which the incident beam is projected). The tilt angle of the optics can be selected such that the transmitted beam will illuminate the internal facets nearly orthogonally, thereby ensuring that substantially all of the illumination light will be transmitted out of the sample without being reflected from any other internal facets.

[0130] 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, where (i) σ = μ nom (ii) The first surface 134a of the optical element is coated with an anti-reflective coating, and (iii) the ICA 112 includes an autocollimator (e.g., a digital or electronic collimator) containing an image sensor. The autocollimator includes an image sensor 224 corresponding to a specific embodiment of the light sensing element 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 the reflected beam (in... Figure 1D and Figure 1E (Indicated by arrow 135). 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 4 As described in the description, or alternatively, if additional information uniquely characterizing each internal facet is available, for example, if the internal facets are designed to differ from each other 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 away from the first internal facet 14a), a second returning beam (caused by reflection away from the second internal facet 14b), or a third returning beam (caused by reflection away from the third internal facet 14c). Similarly, the second spot 201″ can be formed by any one of the returning beams (but a different returning beam from the one forming the first spot 201'), and the third spot 201″′ can be formed by any one of the returning beams (but a different returning beam from each of the returning beams forming the first spot 201' and the second spot 201″). However, as described by way of example below, information such as the average value of the parallelism deviation (also referred to as the average "radial deviation") and the maximum value of the parallelism deviation (also referred to as the maximum "radial deviation") can be extracted from the coordinates of the spot 201.

[0131] As used in this article, the “parallelism radial deviation” between internal facets usually refers to the quantitative deviation of parallelism deviation, which takes into account the deviations of both pitch and roll.

[0132] 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 (measured) coordinates of the first spot 201′, the second spot 201″, and the third spot 201″′ are specified respectively. More precisely, since each spot 201 extends in space (i.e., is not one-dimensional), the vector u... α u β and u γ The center points of the first light spot 201′, the second point 201″, and the third point 201″′ can be specified separately. According to some embodiments, the center point can be calculated by averaging the coordinates of each pixel that constitutes the light spot, which is weighted by the sensed (i.e., measured) intensity of the pixels.

[0133] Vector p α This corresponds to the propagation direction of the returning beam that generates the first light spot 201'. Vector p β This corresponds to the propagation direction of the returning beam that generates the second light spot 201″. 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 p β The magnitude of the angle between them. Angular deviation δ αγ Corresponding to p α The magnitude of the angle between p″′ and the opposite direction. 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 It can then be deduced that, based on the angular deviation, the parallelism deviation (the magnitude) between the internal facets can be inferred.

[0134] Assumption Figure 2A The possible translations of the coordinate system depicted in the figure through the origin and Figure 1DThe coordinate system depicted is consistent. According to some embodiments, where a focusing lens (not shown; e.g., the focusing lens of an autocollimator) with a focal length f focuses the returned beam onto an image sensor (e.g., the image sensor of an autocollimator), a relation can be used. and To calculate the magnitude of the angular deviation between the returned beams.

[0135] Unit vector q α The normal to the inner plane from which the beam that generates the first spot 201' is reflected. 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 γ With q β 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. As will be obvious to those skilled in the art (according to Snell's law), n s ·sin(2ε α )=sin(δ α ), n s ·sin(2ε β )=sin(δ β ), and n s ·sin(2ε γ )=sin(δ γ ).

[0136] 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 will typically be solely attributable to reflection from a particular inner facet, the above expression is independent of the sign of the angular deviation.

[0137] Similarly (through the choice of the depicted coordinate system), the magnitude ε of the pitch deviation between the interior planes... γβ,p ε αγ,p εβα,p We can use the relation tan(δ) respectively γβ,p )=|u β,x -u γ,x | / f1 and n s ·sin(2ε γβ,p )=sin(δ γβ,p ), tan(δ) αγ,p )=|u γ,x -u α,x | / f1 and n s ·sin(2ε αγ,p )=sin(δ αγ,p ) and tan(δ βα,p )=|u α,x -u β,x | / f1 and n s ·sin(2ε βα,p )=sin(δ βα,p The value ε of the roll deviation between the internal flat sections is calculated using this method. γβ,r ε αγ,r ε βα,r We can use the relation tan(δ) to... γβ,r )=|u β , y -u γ,y | / f1 and n s ·sin(2ε γβ,r )=sin(δ γβ,r ), tan(δ) αγ,r )=|u γ,y -u α,y | / f1 and n s ·sin(2ε αγ , r )=sin(δ αγ,r ) and tan(δ βα,r )=|u α,y -u β,y | / f1 and n s ·sin(2ε βα,r )=sin(δ βα,r ) to calculate. 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 αThe 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 (deviation values) 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 (deviation value) of pitch and roll between the internal small planes 14.

[0138] Alternatively, according to some implementation methods, a relational expression can be used. n s ·sin(2ε max )=sin(δ max To quantify the maximum parallelism deviation ε between the internal facets 14 max .

[0139] According to some implementation methods, where the parallelism deviation is sufficiently small, a small-angle approximation can be used. In the case of a small-angle approximation (when calculated 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).

[0140] Also refer to Figure 2B , Figure 2B The light spots 221 and 231 on the photosensitive surface 244 according to some embodiments of system 100 are schematically depicted, where σ = μ nom +Δ and the first surface 134a of the optical element is not coated with an anti-reflective coating (and ICA 112 includes an autocollimator containing an image sensor). The portion of the light spot 231 that leaves the first surface 134a of the optical element by reflection from the incident beam (in Figure 1C and Figure 1D (Indicated by arrow 145)

[0141] The light spot 221 includes a first light spot 221′, a second light spot 221″, and a third light spot 221″′. The two-dimensional vector u′=(u′ x ,u′ y ), u″=(u″ x ,u″ y ) and u″′=(u″′ x ,u″′ y Specify the coordinates (e.g., center points) of the first spot 221′, the second spot 221″, and the third spot 221″′, respectively. Two-dimensional vector v = (v x ,v y The coordinates of light spot 231 are specified. The first light spot 221′ is the light spot within 221 that is closest to light spot 231. d represents the distance between the first light spot 221′ and light spot 231 (i.e., ...). According to some implementations, the tilt angle σ (or more precisely, the magnitude of Δ) of the optical element is selected to ensure that d will be much greater than each of ||u′-v||, ||u″-v||, and ||u″′-v||, thereby ensuring the identification of the light spot 231 (i.e., attributing the light spot 231 to the portion of the incident beam that is reflected away from the first surface 134a of the optical element).

[0142] The 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 calculate the overall (e.g., maximum or average) deviation of parallelism, and / or the deviation of parallelism between one or more pairs of internal facets, based on raw or processed sensing data (i.e., measurement data) from the light sensing component 124. The raw sensing data may include the intensity of the pixels constituting the light spot formed by the returning beam focused on the light sensing component 124. The processed sensing data of the light sensing component 124 may include the angular deviation between (pairs of) returning beams or the center point (e.g., vector u) of the light 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.

[0143] According to some embodiments, one or more processors may include a graphics processing unit (GPU) configured to execute image recognition software to identify spot 201. According to some embodiments 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 spot 231 from spot 221. According to some embodiments, one or more processors may be additionally configured to assign coordinates to each spot (i.e., calculate the center point of each spot).

[0144] According to some embodiments, and as depicted in the figures, the computing module 146 may be communicatively associated with the controller 108, and the sensing data (i.e., measurement data) of the light sensing component 124 may be relayed to the computing module 146 via the controller 108. Alternatively, according to some embodiments, the light sensing component 124 may be configured to send the sensing data directly to the computing module 146. According to some embodiments, the computing module 146 may be included in the system 100.

[0145] Figure 3 A system for verifying the parallelism between internal facets of a sample, according to some embodiments, is schematically depicted; namely, an optical system 300. 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.) System 300 corresponds to a specific embodiment of system 100.

[0146] 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.

[0147] Optical device 304 includes an ICA 312 and an orientable retaining base structure 314, corresponding to specific embodiments of ICA 112 and retaining base structure 114, respectively. ICA 312 includes an autocollimator 352, which includes an image sensor (not shown). According to some embodiments, the autocollimator 352 is a digital autocollimator or an electronic autocollimator. According to some embodiments, the autocollimator 352 is a laser autocollimator. According to some embodiments, ICA 312 may also include an optical mask 356, which includes a slit (elongated aperture) 358. According to some embodiments, the optical mask 356 may be translational to allow the slit 358 to be controllably positioned 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 the optical mask 356 to allow translation of the 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.

[0148] 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.

[0149] 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.

[0150] In operation, according to some embodiments, the optical mask 356 can be laterally translated to position the slits 358 one after another over each inner facet 14. A collimated beam, indicated by arrow 305, is projected onto the optical mask 356 in a direction orthogonal to the first surface 334a of the optical element. When the slits 358 are positioned over the first inner facet 14a, the (first) incident portion of the collimated beam passes through the slits 358, vertically illuminating the first surface 334a of the optical element, and is transmitted through the first surface 334a into the optical element 302, thereby obtaining a transmitted light beam. The first incident portion is indicated by arrow 355a, and the transmitted beam is indicated by arrow 315a. The transmitted beam travels through the optical element 302, traverses (i.e., transmits) through the second surface 334b ​​of the optical element and the first surface 16a of the sample into the sample 10, and propagates from the first surface 16a of the sample toward the first inner facet 14a. The transmitted beam is reflected away from the first internal plane 14a and returns toward the first surface 16a of the sample.

[0151] The first reflected beam—corresponding to the portion of the transmitted beam reflected from the first internal facet 14a—is indicated by arrow 325a. The first reflected beam exits from sample 10 via the first surface 16a of the sample and is transmitted into optical element 302 via the second surface 334b ​​of the optical element. The first reflected beam travels from the second surface 334b ​​to the first surface 334a of the optical element and exits from optical element 302 (e.g., refracted), thus obtaining a first returned beam. The first returned beam is indicated by arrow 335a. After passing through slit 358, the first returned beam travels to autocollimator 352 and is sensed by the image sensor of autocollimator 352.

[0152] The trajectories of the second incident portion, the second transmitted beam, the second reflected beam, and the second returned beam are indicated by dashed arrows 355b, 315b, 325b, and 335b, 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, and 335b 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, and the third returned beam are indicated by dashed arrows 355c, 315c, 325c, and 335c, respectively. This 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 and 335c are shown by dashed lines to indicate that the trajectory was not achieved when slit 358 was positioned above the first inner facet 14a (i.e., there was no corresponding beam when slit 358 was positioned above the first inner facet 14a).

[0153] 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.

[0154] According to some alternative embodiments, the optical mask 356 can be moved between different positions in a plurality of locations. At each of these locations, the slit 358 is positioned above a corresponding internal facet 14. Alternatively, according to some embodiments, the collimated beam 305 is projected only when the optical mask 356 is in one of the (different) positions.

[0155] Also refer to Figure 4 , Figure 4 A light spot 401 on a digital display 464 associated with an autocollimator 352 is schematically depicted according to some embodiments of system 100, where σ = μ nomFurthermore, 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 of the returning beams generated each of the light spots 401. Therefore, the parallelism deviation between each pair of internal facets 14 can be calculated, as explained below. The first light spot 401a is formed by the first returning beam (in... Figure 3 (Indicated by arrow 335a). The second spot 401b is formed by the second returning beam (in... Figure 3 (Indicated by arrow 335b). The third spot 401c is formed by the third returning beam (in... Figure 3 (Indicated by arrow 335c).

[0156] 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 u1, u2, and u3.

[0157] 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 δ 31,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 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 deviation ε of the second inner facet 14b relative to the first inner facet 14a. 21,p and roll deviation ε 21,r Using n respectively s ·sin(2ε 31,p )=sin(δ 31,p ) and n s ·sin(2ε 31,r )=sin(δ 31,r To calculate the pitch deviation ε of the third inner plane 14c relative to the first inner plane 14a. 31,p and roll 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 deviation ε of the third inner plane 14c relative to the second inner plane 14b. 32,p and roll deviation ε 32,r .

[0158] 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.

[0159] According to some implementation methods, 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 calculated 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).

[0160] 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 between one of the internal facets (e.g., the lateralmost internal facet) and each of all other internal facets. According to some embodiments, the calculation module 346 can also be configured to additionally calculate the uncertainty of the calculated parallelism deviation.

[0161] According to some alternative embodiments not depicted in the figures, instead of optical device 304, system 300 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 34. According to some such embodiments, the interferometric measuring device may include a beam splitter array and an associated array of controllably opening and closing optical blocking filters configured to allow examination of pairs of internal facets one at a time. More specifically, the beam splitter and optical blocking filter array may be configured to (i) split the incident beam into selectable pairs of incident sub-beams perpendicularly incident on optical element 302, and (ii) recombine the two returning sub-beams caused by each pair of incident beams into a single combined returning beam, which is then sensed by a light sensor. The beam splitter and optical blocking filter array is configured such that each selectable pair of incident sub-beams will cause reflections from a corresponding pair of internal facets, such that 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 from the i-th inner facet (after it is transmitted into, through and into the optical element 302, and into the sample 10), and the second incident sub-beam will cause reflection from the j-th inner facet (after it is transmitted into, through and into the optical element 102, and into the sample 10), 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.

[0162] Figure 5 A 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 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 top surface 578a and an outer, flat bottom surface 578b opposite the top surface 578a. According to some embodiments, the top surface 578a may be tilted relative to the bottom surface 578b at a platform tilt angle ι, which may be approximately equal to the nominal angle μ. nom .

[0163] The orientation of optical element 502 can be adjusted by orienting pitch goniometer 572 and roll goniometer 574, thereby allowing the incident angle of the light beam projected onto optical element 502 to be controllably set, for example, by ICA (not shown). According to some embodiments, each of pitch goniometer 572 and roll goniometer 574 can be oriented using a programmable micrometer (not shown). Additionally or alternatively, according to some embodiments, each of pitch goniometer 572 and roll goniometer 574 can be manually oriented.

[0164] It also indicates the tilt angle σ′ of the optical element 502, which can be approximately equal to the nominal angle μ. nom .

[0165] method

[0166] 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 6 A flowchart of such a method (optics-based method 600) according to some embodiments is presented. Method 600 may include:

[0167] - Stage 610, wherein a sample to be inspected (e.g., sample 10) is provided. The sample includes samples with a refractive index n. s The light-transmitting substrate and two or more nominally parallel internal facets (e.g., internal facet 14). Each internal facet is nominally positioned relative to the outer and flat surface of the sample at an angle μ. nom (For example, nominal angle μ) nom )tilt.

[0168] - Stage 620, 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. The optical element includes an external, flat first surface and an external, flat second surface, the second surface being opposite to the first surface of the optical element and at an angle approximately equal to the nominal angle μ. nom The angle σ is tilted.

[0169] - Stage 630, wherein the sample and optical element are positioned such that the second surface of the optical element is parallel to and adjacent to the surface of the substrate.

[0170] - Stage 640, wherein multiple incident light beams are projected onto the first surface of the optical element approximately perpendicularly (e.g., within 1°, 1.5° or even 2° of perpendicular incidence).

[0171] - Stage 650, wherein multiple return beams are obtained after the incident beam passes through the optical element, is transmitted into the sample and reflected away from the internal plane, passes through the optical element again and exits the optical element via the first surface of the optical element (e.g., refracted out).

[0172] - Stage 660, in which multiple return beams are sensed (e.g., measured using a light sensing component 124).

[0173] - Stage 670, wherein, based on the sensed data (measured data), at least one parallelism deviation between at least some internal facets is calculated.

[0174] As used herein, the term "obtain" can be used in both active and passive senses. Thus, for example, in stage 650, the return beam may be obtained not as a result of any operation performed in stage 650, but rather as a result of the generation of the incident beam in stage 640. 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.

[0175] Method 600 can be used to verify the parallelism of the internal facets of a sample such as sample 10 (including any embodiment of sample 10 described above). In particular, method 600 can be used to verify the parallelism of the internal facets of a one-dimensional reflecting waveguide and a two-dimensional reflecting waveguide.

[0176] Method 600 can be implemented using an optical system such as any of systems 100 and 300 detailed above in their respective descriptions, or similar systems. According to some embodiments, the optical element may be a prism.

[0177] According to some implementation methods, σ = μ nom According to some such embodiments, in order to eliminate the need to distinguish between the returning beam and the 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. Alternatively, according to some embodiments, σ ​​= μ nom +Δ. According to some such implementations, as described above... Figure 2B As described, the first surface of the optical element is not coated with an anti-reflective coating and |Δ| is sufficiently large to ensure that the returned beam is distinguishable 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 separate embodiment. An upper bound on the value of Δ can be chosen to ensure that the light spot formed on the image sensor is not blurred.

[0178] According to some embodiments, particularly those in which (i) the surface of the sample and / or the first surface of the optical element is not sufficiently polished and / or fails to be aligned with sufficient precision and (ii) the light source used is multicolor or not sufficiently monochromatic, in order to eliminate or at least mitigate dispersion, the optical element may be positioned between the sample having approximately the same (e.g., greater than n) shape as the substrate (constituting the main body of the sample). s -0.02 and less than n s The shape of the refractive index (+0.02) conforms to the interface, as described above in the description of system 100.

[0179] According to some embodiments, in stage 640, the incident beam can form a complementary portion of the collimated extended beam. According to some embodiments, the incident beam can form a complementary portion of the extended laser beam.

[0180] According to some implementations, the internal facets are inspected (i.e., probed) one at a time. More specifically, according to some implementations, stages 640, 650, and 660 can be implemented N times, where N is the number of internal facets, and where in each implementation, light illuminates only one of the internal facets, as described above in the description of system 300 and some implementations of system 100. System 300 or similar systems can be used to perform individual inspections of the internal facets.

[0181] According to some embodiments, stages 640, 650, and 660 are implemented using an autocollimator, for example, substantially as described above in the description of system 100 and its various embodiments (including system 300). According to some embodiments, the autocollimator includes an image sensor. In some such embodiments, in stage 660, the image sensor of the autocollimator can be used to sense the returning beam. Alternatively, according to some embodiments, the autocollimator is a visual autocollimator, and the returning beam is sensed using the eyepiece assembly of the autocollimator (through which scale lines are viewed).

[0182] According to some embodiments in which an image sensor is used to sense the returned beams, stage 670 may include an initial sub-stage in which image recognition software is used to identify light spots (e.g., spot 201, spot 221, or spot 401) formed by each returned beam on the photosensitive surface of the image sensor. 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 pixel constituting a light spot weighted by the sensed (i.e., measured) intensity of the pixels. According to some embodiments in which the first surface of the optical element is not coated with a reflective coating such that additional light spots (e.g., spot 231) can be formed on the photosensitive surface of the image sensor (i.e., by directly reflecting light leaving the first surface of the optical element), the image recognition software may also be configured to distinguish the additional light spots from the light spots formed by the returned beams.

[0183] According to some embodiments that examine the internal facets one at a time, in stage 670, the parallelism deviation between pairs of adjacent internal facets is calculated. Additionally or alternatively, according to some embodiments, the parallelism deviation between one of the internal facets (e.g., the lateralmost internal facet) and each of the other internal facets 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 average and / or maximum parallelism deviations are calculated (e.g., between adjacent internal facets and / or between the lateralmost internal facet and each of the other internal facets). According to some embodiments, average and / or maximum pitch deviation and / or average and / or maximum roll deviation may be calculated.

[0184] According to some implementation methods, the relation tan(δ) can be used. ij,p )=(x i -x j ) / f 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 x i and x j These are the x-coordinates (e.g., the horizontal coordinates of the center point of the spot on the image sensor) of the i-th and j-th return beams, respectively, determined under the implicit assumption that the coordinate system is such that the x-coordinate of the spot is determined by the pitch of the corresponding inner facet. Similarly, this can be achieved via tan(δ ij,r )=(y i -y j ) / f and n s ·sin(2εij,r )=sin(δ ij,r To calculate the roll deviation ε between the i-th and j-th inner facets. ij,r y i and y j These are the y-coordinates (e.g., the vertical coordinates of the center point of the spot on the image sensor) of the i-th and j-th return beams, respectively, which are determined by the implicit assumption that the coordinate system is such that the y-coordinate of the spot is determined by the roll of the corresponding inner facet.

[0185] Relational expressions can be used and n s ·sin(2ε ij )=sin(δ ij To calculate the parallelism deviation ε of the i-th inner facet relative to the j-th inner facet. ij The value of.

[0186] According to some implementations, where the parallelism deviation is sufficiently small, a small-angle approximation can be used. As will be readily apparent to those skilled in the art, under a small-angle approximation (when calculated in radians), ε ij,p =(x i -x j ) / (2n s ·f) and ε ij,r =(y i -y j ) / (2n s ·f).

[0187] Based on the fact that the first surface of the optical element is not coated with an anti-reflective coating and σ = μ nom Some implementations of +Δ can use the relation tan(δ′) i,p )=(x″–x i ′) / f and n s ·sin(2ε′ i,p )=sin(δ′ i,p ) and tan(δ′ i,r )=(y″–y i ′) / f and n s ·sin(2ε′ i,r )=sin(δ′ i,r To calculate the pitch deviation ε of each internal facet from the nominal orientation. i,p and roll deviation and ε i ′ ,r For each i, x i ′ and y i′ is the determined x and y coordinates of the light spot caused by the light beam reflected from the i-th internal small plane. x″ and y″ are the determined x and y coordinates of the light spot formed by the light beam reflected directly from the first surface of the optical element.

[0188] According to some implementations, determining the coordinates of the light spot may include calculating the associated uncertainty, and based on this, calculating the uncertainty of the parallelism deviation between pairs of internal facets.

[0189] According to some embodiments where the internal facets are not examined one at a time (e.g., all internal facets are examined simultaneously), such that each spot (formed by the returning beam) cannot typically be attributed to one of the internal facets (at least not without additional data), in stage 670, the average radial deviation of parallelism (i.e., the average deviation value) and / or the maximum radial deviation of parallelism (i.e., the deviation value) are calculated. More specifically, according to some embodiments, this can be achieved by using a relational expression... and n s ·sin(2ε ij )=sin(δ ij )calculate To obtain the average radial deviation of parallelism. 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. lm It is the magnitude of the 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. (x) l "′,y l "′) and (x m "′,y m "″′) are the calculated coordinates (e.g., center points) of the l-th and m-th light spots, respectively. M is the number of (distinct) interior plane pairs. This can be calculated by max{ε lm} l，m＞l To obtain the radial deviation of parallelism.

[0190] According to some implementations, pitch and roll deviations relative to the nominal orientation of each internal facet can be calculated additionally (or alternatively). For this purpose, a formula equal to μ can be used. nom The optical element is characterized by a tilt angle σ of +Δ (and the first surface of the optical element not coated with an anti-reflective coating).

[0191] Laboratory results

[0192] Figure 7A and Figure 7BLaboratory results obtained using the disclosed methods and systems according to some embodiments are presented. Two reflecting waveguides were examined: a first waveguide and a second waveguide. Each waveguide comprises six internal facets. (See reference...) Figure 7A The x-axis enumerates the internal facets, and the y-axis lists the magnitudes of the angles between a reference internal facet (in this case, the first internal facet, which is also the lateral facet) and each of the other facets. The solid curve 710a relates to the first waveguide, while the dashed curve 720a relates to the second waveguide. Each curve is fitted (i.e., obtained using fitting techniques) based on the uncertainty of the (calculated) magnitudes of the angles. Solid vertical bars 730a (not all solid vertical bars are numbered) represent the uncertainty related to the first waveguide. Dashed vertical bars 740a (not all dashed vertical bars are numbered) represent the uncertainty related to the second waveguide.

[0193] Reference Figure 7B The x-axis lists the internal facets, while the y-axis lists the magnitudes of the angles between consecutive internal facets (i.e., the angle between the first and second internal facets, the angle between the second and third internal facets, etc.). The solid curve 710b relates to the first waveguide, while the dashed curve 720b relates to the second waveguide. Each curve is fitted based on the uncertainty (represented by vertical bars) of the (calculated) angle magnitudes. The solid vertical bars 730b (not all solid bars are numbered) represent the uncertainty related to the first waveguide. The dashed vertical bars 740b (not all dashed vertical bars are numbered) represent the uncertainty related to the second waveguide.

[0194] 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.

[0195] 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.

[0196] 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. Specific stages in the disclosed method should not be considered essential stages of the method unless expressly specified otherwise.

[0197] 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.

[0198] The wording and terminology used herein are for descriptive purposes and should not be construed as restrictive. Any reference or designation in this application should not be interpreted as an admission that such reference can be used as prior art within 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 substrate and two or more internal facets, said two or more internal facets being embedded in the substrate and relative to the external and flat surface of the sample at a nominal acute angle μ. nom The system, nominally oriented, includes a light-transmitting optical element and an optical device, wherein the optical device includes a light source and a light-sensing component. The optical element has approximately equal to n s The refractive index includes an external and flat first surface and an external and flat second surface, the external and flat first surface and the external and flat second surface being opposite each other and defining an angle approximately equal to the nominal acute angle μ between them. nom ; The optical device is configured to position the sample and / or the optical element such that: (i) the second surface of the optical element is parallel to and adjacent to the surface of the sample, and (ii) when positioned in this way, a light beam generated by the light source is incident on the first surface of the optical element approximately perpendicular to the first surface; The optical device is further configured to focus the returned beam onto the photosensing component, thereby enabling the determination of the angular deviation between the returned beams; and The returned beam is obtained after the incident beam passes through the optical element, is transmitted into the sample and reflected away from the internal facet, passes through the optical element again and exits the optical element via the first surface of the optical element, and the angular deviation 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 incident light beam.

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

4. The system according to claim 1, wherein, The optical device includes a focusing lens or focusing lens assembly configured to focus an outgoing light beam onto the photosensitive component.

5. The system according to claim 1, wherein, The second surface of the optical element is relative to the first surface of the optical element at a distance equal to μ. nom + Δ, where |Δ| is greater than approximately 0.1° and less than approximately 1°.

6. The system according to claim 1, wherein, The second surface of the optical element is relative to the first surface of the optical element at the nominal acute angle μ. nom tilt.

7. The system according to claim 6, wherein, The first surface of the optical element is coated with an anti-reflective coating.

8. The system according to claim 1, wherein, The optical device includes an orientation base structure configured to orient the sample.

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

10. The system according to claim 1 further includes an autocollimator, the autocollimator comprising the light source.

11. The system according to claim 10, wherein, The autocollimator also includes the light sensing component.

12. The system according to any one of claims 1 to 11, wherein, The light-sensing component includes an image sensor configured to sense the returned light beam.

13. The system according to claim 1, wherein, The light sensing component is or includes a camera device.

14. The system according to claim 1, wherein, The light-sensing component includes an eyepiece assembly, which includes scale markings.

15. 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.

16. The system of claim 12, further comprising a calculation module configured to calculate the parallelism deviation between the internal facets based on sensing data of the returned beam obtained by the image sensor.

17. The system according to claim 16, wherein, The sensing data associated with each returning beam includes the measured intensity of the pixels that make up the corresponding spot formed by the returning beam on the image sensor.

18. The system according to claim 16, wherein, The calculation module is configured to calculate the angular deviation between the returned beams as part of the calculation of the parallelism deviation between the internal facets.

19. The system according to claim 16, wherein, Calculating the parallelism deviation includes: calculating ε avg and / or ε max , where ε avg equal , and ε max equal or ,and , where ε ij ε represents the parallelism deviation between the i-th and j-th inner facets. avg Represents ε ij The average value, ε max ε ij The maximum value, and the indices i and j involve different inner plane pairs, is a set of two-dimensional vectors specifying the positions of the i-th and j-th light spots on the image sensor, N is the number of the internal facets, M = N · (N - 1) / 2, and f is the focal length of the focusing lens or focusing lens assembly configured to focus the returned beam on the image sensor.

20. The system according to claim 16, 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 plurality of internal facets.

21. The system according to claim 20, wherein, Calculating the parallelism deviation between the paired internal facets includes: calculating the 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 Where indices i and j involve different inner plane pairs, and ε ij, p and ε ij, r These are the pitch deviation and roll deviation between the i-th and j-th internal small planes, respectively.

22. The system according to claim 21, wherein, 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 the ε ij, p and the ε ij,r , where δ ij, p The pitch deviation δ is the difference between the i-th returning beam caused by reflection from the i-th internal plane and the j-th returning beam caused by reflection from the j-th internal plane. ij, r It is the roll deviation between the i-th returning beam and the j-th returning beam. It is a set of two-dimensional vectors that specify the position of the spot on the image sensor caused by the returned beam, the index enumerating the beam, N being the number of the internal facets, and f being the focal length of the focusing lens or focusing lens assembly configured to focus the returned beam on the image sensor.

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