Method and system for verifying parallelism between internal facets

Abstract

Disclosed herein is a method comprising: (i) providing a light-transmitting sample including nominally parallel internal facets that are approximately perpendicular to an exterior surface of the sample; (ii) providing an optical element having a refractive index approximately equal to that of the sample and including an outer first surface and an outer second surface inclined at an acute angle relative to the outer first surface; (iii) positioning the second surface of the optical element adjacent to the first surface of the sample; (iv) impinging a light beam on the first surface of the optical element in a direction approximately normal to the first surface; (v) sensing the impinging light beam as it passes through the optical element, transmits into the sample, and exits the sample after being reflected once from the internal facets; and (vi) calculating deviations from parallelism between the internal facets based on the sensed data.

Description

[Technical Field]

[0001] This disclosure relates, in general terms, to methods and systems for measuring samples including internal facets. [Background technology]

[0002] Some optical waveguides contain reflective internal facets that are nominally parallel. Current state-of-the-art technology requires high-end optical components to verify the parallelism of such internal facets with high precision. There is an unmet need in this field for simple, easily implementable measurement techniques that avoid the use of high-end optical components and thereby meet the demands of mass production. [Overview of the project]

[0003] Aspects of the present disclosure, according to some embodiments thereof, relate to methods and systems for measuring samples including internal facets. More specifically, according to some embodiments of the present disclosure, though not limited thereto, aspects of the present disclosure relate to optical methods and systems for measuring samples including a plurality of nominally parallel internal facets. Even more specifically, according to some embodiments of the present disclosure, aspects of the present disclosure relate to optical methods and systems for measuring reflective waveguides including a plurality of nominally parallel internal facets, wherein the plurality of nominally parallel internal facets are perpendicular to the main surface of the waveguide.

[0004] Reflective waveguides are used in a variety of displays, including head-mounted displays, head-up displays, smartphones, compact displays, 3D displays (stereo displays), and compact beam expanders. A reflective waveguide contains multiple nominally parallel internal facets across the waveguide's output section. Light propagating from the waveguide's coupling-in section towards the output section (by total internal reflection) is gradually coupled away from the waveguide through partial reflection and transmission at each of the internal facets. High parallelism between internal facets, especially between adjacent internal facets, helps ensure that a sharp, clear image (without duplication or blurring) is formed on the display.

[0005] Several methods are known in the art for monitoring the parallelism of internal facets within a plate stack before dicing the reflective waveguide into individual units. However, changes in the parallelism of internal facets may occur from these early stages of manufacturing to the finished product (i.e., until the manufacturing of the reflective waveguide is complete).

[0006] In the art, there is an unmet need for an improved method for verifying the parallelism of internal facets in (finished) reflective waveguides, as well as in later stages of their manufacture. Advantageously, this application discloses a fast, simple, and accurate method for verifying the parallelism between internal facets of a reflective waveguide. The application further discloses a system that can implement the disclosed method, advantageously avoiding the use of high-end and / or complex components.

[0007] Accordingly, according to some embodiments, an optical-based method is provided for verifying the parallelism between internal facets of a sample. This method includes the following steps: -refractive index n sTo provide a sample comprising a light-transmitting substrate having two or more internal facets. The internal facets are embedded within the substrate, nominally parallel, and substantially perpendicular to a first, flat surface on the outside of the sample. -n s To provide a first optical element (FOE) having a refractive index approximately equal to . The FOE includes an outer, flat first surface and an outer, flat second surface. The second surface of the FOE is opposite the first surface of the FOE and is inclined at a first acute angle with respect to the first surface of the FOE. - Position the sample and FOE such that the second surface of the FOE is adjacent to the first surface of the sample. - Projecting a first set of light beams onto the first surface of the FOE in a direction approximately normal to (i.e., approximately perpendicular to) the beams. - Acquire a second set of light beams. Each of the first set of light beams travels through (i.e., through) the FOE, penetrates into the sample, is reflected once from the internal facets, and then exits the sample. - Sensing (i.e., measuring) a second set of light beams. - Based on the sensed data (obtained by sensing a second set of light beams), calculate at least one deviation from the parallelism between at least some of the internal facets.

[0008] According to some embodiments of the method, the FOE is n s It has a refractive index equal to .

[0009] According to some embodiments of the method, a first set of light beams are projected in a direction normal to a first surface of the FOE.

[0010] According to some embodiments of the method, the step of calculating the deviation from parallelism includes calculating the angular deviation between a second set of light beams (i.e., the angle formed between the light beams).

[0011] According to some embodiments of the method, a first set of light beams constitute a complementary portion of the collimated, expanded light beam.

[0012] According to some embodiments of the method, the expanded light beam is monochromatic.

[0013] According to some embodiments of the method, the expanding light beam is an expanding laser beam.

[0014] According to some embodiments of the method, the FOE is a prism. According to some such embodiments, the FOE is a triangular prism.

[0015] According to some embodiments of the method, the sample is formed as a thin slab or an elongated box.

[0016] According to some embodiments of the method, the sample is a one-dimensional reflective waveguide or a two-dimensional reflective waveguide.

[0017] According to some embodiments of the method, in the step of sensing a second plurality of light beams, the second plurality of light beams are sensed using an image sensor. The sensed data acquired thereby includes the measured intensity of pixels that make up spots on a component. Each of the spots is induced by the respective second plurality of light beams.

[0018] According to some embodiments of the method, the step of sensing a second plurality of light beams includes viewing the second plurality of light beams through an eyepiece. The second plurality of light beams appear as spots relative to the graduated reticle of the eyepiece.

[0019] According to some embodiments of the method, the step of calculating the deviation from parallelism is ε avg and / or ε max This includes calculating ε. avg teeth,

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[0020] According to some embodiments of the method, each of the first plurality of light beams continues to be reflected from each internal facet in the sample.

[0021] According to some embodiments of the method, a first set of light beams are projected sequentially so that the internal facets are inspected one at a time.

[0022] According to some embodiments of the method, continuous projection is implemented using a translationable slit-type optical mask or aperture-type optical mask or multiple shutters.

[0023] According to some embodiments of the method, in calculating the deviation from parallelism, the deviation from parallelism from two or more internal facets between pairs of internal facets is calculated.

[0024] According to some embodiments of the method, the pair of internal facets includes pairs of adjacent internal facets.

[0025] According to some embodiments of the method, calculating the deviation from parallelism between pairs of internal facets involves calculating (two) sets of deviations of the pitch {ε ij,p} i、j and / or roll {ε ij,r} i、j between the internal facets of each pair of internal facets. The indices i and j range over different pairs of internal facets (from the pair of internal facets). ε ij,p and ε ij,r are the pitch and roll deviations between the i-th internal facet and the j-th internal facet, respectively. According to some such embodiments, ε ij,p and ε ij,r are, respectively, 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), where δ ij,p is the pitch deviation between the i-th light beam of the second plurality of light beams induced by reflection from the i-th internal facet and the j-th light beam of the second plurality of light beams induced by reflection from the j-th internal facet. δ ij,r is the roll deviation between the i-th light beam of the second plurality of light beams and the j-th light beam of the second plurality of light beams.

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[0026] According to some embodiments of the method, the step of calculating the deviation from parallelism is to determine the maximum deviation of pitch between internal facets (i.e., the range of pitch deviations) ε max,p =(max{x i} i -min{x i} i ) / (2n s f) The maximum deviation of the roll between and / or internal facets (i.e., the range of roll deviations) ε max,r =( max{y i} i -min{y i} i ) / (2n s f) Includes calculation.

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[0027] According to some embodiments of the method, in the step of positioning the sample and FOE, the sample and FOE are positioned such that the second surface of the FOE is parallel to the first surface of the sample.

[0028] According to some embodiments of the method, the sample and the FOE are positioned such that a first area on the first surface of the sample is in complete contact with the second surface of the FOE. The first area is defined by a section of the sample containing internal facets.

[0029] According to some embodiments of the method, in the step of calculating the deviation from parallelism, the deviation from parallelism between adjacent pairs of internal facets is calculated from two or more internal facets.

[0030] According to some embodiments of the method, in the step of calculating the deviation from parallelism, the deviation from parallelism of an internal facet, the deviation from two or more internal facets, the deviation relative to a reference internal facet (e.g., the internal facets of the lateral edges), and the deviation from two or more internal facets are calculated.

[0031] According to some embodiments of the method, the first surface of the FOE is coated with an anti-reflective coating.

[0032] According to some embodiments of the method, the method further includes applying a shape-fitting interface between the FOE and the sample. The shape-fitting interface has a refractive index substantially the same as that of the substrate. According to some such embodiments, the shape-fitting interface may be a liquid, gel, or paste.

[0033] According to some embodiments of the method, an autocollimator is used to generate a first plurality of light beams and to focus a second plurality of light beams onto a photosensing component used to sense the second plurality of light beams.

[0034] According to some embodiments of the method, the second set of light beams includes a light beam returned from the sample via a first surface of the sample and a light beam returned from the sample via the FOE.

[0035] According to some embodiments of the method, the sample includes an outer, flat second surface opposite a first surface of the sample. The returned light beam is reflected from the second surface of the sample before it exits the sample through the first surface of the sample.

[0036] According to some embodiments of the method, the internal facets are perpendicular to the first surface of the sample. The second surface of the sample is parallel to the first surface of the sample.

[0037] According to some embodiments of the method, adjacent internal facets of the sample are spaced at regular intervals. The first tilt angle is equal to approximately (90° - arctan(2d1 / d2)), i.e., the tilt angle σ is equal to 90 degrees minus arctan(2d1 / d2). d1 is the distance between the first surface of the sample and the second surface of the sample. d2 is the distance between adjacent internal facets of the sample.

[0038] According to some embodiments of the method, the first tilt angle is such that the ratio of the power of the second plurality of light beams to the power of the first plurality of light beams is approximately maximized.

[0039] According to some embodiments of the method, the sample includes an outer, flat second surface opposite to a first surface of the sample. The second plurality of light beams include light beams that exit the sample through the second surface of the sample.

[0040] According to some embodiments of the method, the method further includes providing a second optical element (SOE) prior to the step of projecting a first plurality of light beams. The SOE is n sIt has a refractive index approximately equal to . The SOE includes an outer, flat first surface and an outer, flat second surface. The second surface of the SOE is opposite the first surface of the SOE and is inclined at a second acute angle with respect to the first surface of the SOE. The step of positioning the sample and FOE further includes positioning the SOE and / or the sample such that the second surface of the SOE is adjacent to the second surface of the sample. The second plurality of light beams include light beams that exit the sample through the second surface of the sample, pass through the SOE into the SOE, and then exit the SOE through the first surface of the SOE. According to some such embodiments, the SOE is n s It has a refractive index equal to .

[0041] According to some embodiments of the method, in the step of positioning the sample and FOE, the sample, FOE, and SOE are positioned such that the second surface of the FOE is parallel to the first surface of the sample and the second surface of the SOE is parallel to the second surface of the sample.

[0042] According to some embodiments of the method, the second inclination angle is approximately equal to the first inclination angle, and therefore each of the second plurality of light beams exits from the SOE in a direction normal to the first surface of the SOE. According to some such embodiments, the second inclination angle is equal to the first inclination angle.

[0043] According to some embodiments of a method in which the internal facets of a sample are perpendicular to the first surface of the sample and the second surface of the sample is parallel to the first surface of the sample, adjacent internal facets of the sample are spaced at regular intervals. Each of the first and second inclination angles is equal to approximately (90° - arctan(d1 / d2)), i.e., the inclination angle σ is equal to 90 degrees minus arctan(d1 / d2). d1 is the distance between the first surface of the sample and the second surface of the sample. d2 is the distance between adjacent internal facets of the sample.

[0044] According to some embodiments of the method, the first and second inclination angles are such that the ratio of the power of the second plurality of light beams to the power of the first plurality of light beams is approximately maximized.

[0045] According to some embodiments of the method, the SOE is a prism. According to some such embodiments, the SOE is a triangular prism.

[0046] According to some embodiments of the method, the sample, FOE, and SOE are arranged such that a first region on the first surface of the sample is in complete contact with the second surface of the FOE, and a second region on the sample is in complete contact with the second surface of the SOE. The first and second regions are defined by sections of the sample containing internal facets. The second region is opposite the first region.

[0047] According to some embodiments of the method, the first surface of the SOE is coated with an anti-reflective coating.

[0048] According to some embodiments of the method, the method further includes applying shape-fitting interfaces between the FOE and the sample, and between the SOE and the sample. The shape-fitting interfaces have substantially the same refractive index as the substrate. According to some such embodiments, the shape-fitting interfaces may be a liquid, gel, or paste.

[0049] According to some embodiments, an optical-based system for measuring a sample is provided, with refractive index n s The system comprises a substrate having and two or more internal facets, the internal facets being embedded in the substrate, nominally parallel, and substantially perpendicular to the outer, flat first surface of the sample. The system includes a first optical element (FOE) and an optical setup including a light source, optical instruments, and a light-sensing component. The FOE is n sThe FOE has a refractive index approximately equal to 1, and includes an outer, flat first surface and an outer, flat second surface. The second surface of the FOE is opposite the first surface of the FOE and is inclined at a first acute angle of inclination with respect to the first surface of the FOE. The optical setup is configured to allow positioning of the sample and / or FOE such that (i) the second surface of the FOE is adjacent to the first surface of the sample, and (ii) when positioned in this manner (i.e., when the second surface of the FOE is adjacent to the first surface of the sample), a first plurality of light beams that can be generated by the light source collide with the first surface of the FOE approximately normal to it. The FOE is further configured to allow focusing of a second plurality of light beams, which pass through the FOE, through into the sample, and after being reflected from the internal facets, onto a photosensing component, thereby allowing measurement of the angular deviation between the second plurality of light beams. The angular deviation between the second plurality of light beams represents the deviation from the parallelism between the internal facets.

[0050] According to some embodiments of the system, FOE is n s It has a refractive index equal to .

[0051] According to some embodiments of the system, the optical setup is configured to allow positioning of a second surface of an FOE adjacent to a first surface of a sample such that a first plurality of light beams, which can be generated by a light source, collide with the first surface of the FOE in a direction normal to the first surface of the FOE.

[0052] According to some embodiments of the system, the optical instrument includes a collimating lens or collimating lens assembly configured to collimate a light beam generated by a light source, thereby preparing a first plurality of light beams.

[0053] According to some embodiments of the system, the light source is a monochromatic light source.

[0054] According to some embodiments of the system, the light source is a laser source.

[0055] According to some embodiments of the system, the optical instrument includes a focusing lens or focusing lens assembly configured to focus a second plurality of light beams onto a photosensing component.

[0056] According to some embodiments of the system, the light-sensing component includes a component configured to sense a second plurality of light beams.

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

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

[0059] According to some embodiments of the system, the optical setup is configured to allow positioning of the sample and / or FOE such that the second surface of the FOE is parallel to the first surface of the sample.

[0060] According to some embodiments of the system, the optical setup is configured to allow positioning of the sample and FOE such that a first area on the first surface of the sample is in full contact with a second surface of the FOE. The first area is defined by a section of the sample containing internal facets.

[0061] According to some embodiments of the system, the sample is formed as a thin slab or an elongated box.

[0062] According to some embodiments of the system, the sample is a one-dimensional reflective waveguide or a two-dimensional reflective waveguide.

[0063] According to some embodiments of the system, the FOE is a prism. According to some such embodiments, the FOE is a triangular prism.

[0064] According to some embodiments of the system, the optical setup further includes a translationable slit-type or aperture-type optical mask, and / or a plurality of shutters, configured to allow inspection of internal facets one at a time.

[0065] According to some embodiments of the system, the sensed data includes the measured intensity of pixels that make up a spot on the image sensor. Each of the spots is induced by a second plurality of respective light beams.

[0066] According to some embodiments of the system, the system further includes a computation module configured to calculate deviations from parallelism between internal facets based on sensed data.

[0067] According to some embodiments of the system, as part of the calculation of deviations from parallelism, the calculation module is configured to calculate the angular deviation between a second set of light beams (based on the sensed data).

[0068] According to some embodiments of the system, the computation module calculates the quantity ε avg and / or ε max It is configured to calculate ε. avg teeth,

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[0069] According to some embodiments of the system, the optical setup further includes a translationable slit-type or aperture-type optical mask and / or multiple shutters configured to allow inspection of internal facets one at a time, and a calculation module configured to calculate the deviation from parallelism between pairs of internal facets from two or more internal facets. According to some such embodiments, a pair of internal facets includes a pair of adjacent internal facets.

[0070] According to some embodiments of the system, as part of the calculation of the deviation from parallelism between pairs of internal facets, the calculation module calculates the pitch between internal facets {ε} in each pair of internal facets. ij,p} i,j and / or roll {ε ij,r} i,j It is configured to calculate a set of deviations in ε. The indices i and j are ranges on different pairs of inner facets (from pairs of inner facets). ij,p and ε ij,r These are the pitch and roll deviations between the i-th internal facet and the j-th internal facet, respectively. According to some such embodiments, ε ij,p and ε ij,r These are, respectively, ε ij,p =δ ij,p / (2ns )=(x i -x j ) / (2n s f) and ε ij,r =δ ij,r / (2n s )=(y i -y j ) / (2n s It is calculated via f). δ ij,p δ is the pitch deviation between the i-th light beam, one of a second set of light beams induced by reflection from the i-th internal facet, and the j-th light beam, one of a second set of light beams induced by reflection from the j-th internal facet. ij,r This is the roll deviation between the i-th light beam of the second set of multiple light beams and the j-th light beam of the second set of multiple light beams.

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[0071] According to some embodiments of the system, the calculation module calculates the deviation from parallelism between internal facets as part of the calculation of internal facet ε max,p =(max{x i} i -min{x i} i ) / (2n s f) The maximum pitch deviation (i.e., the range of pitch deviations) and / or internal facet ε max,r =( max{y i} i -min{y i} i ) / (2n s It is configured to calculate the maximum deviation of the rolls between f) (i.e., the range of roll deviations).

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[0072] According to some embodiments of the system, the optical setup is configured to allow positioning of the sample and / or FOE such that the second surface of the FOE is parallel to the first surface of the sample.

[0073] According to some embodiments of the system, the optical setup is configured to allow positioning of the sample and / or FOE such that a first area on a first surface of the sample is in full contact with a second surface of the FOE. The first area is defined by a section of the sample containing internal facets.

[0074] According to some embodiments of the system, as part of calculating deviations from parallelism, the calculation module is configured to calculate deviations from parallelism between pairs of adjacent internal facets from two or more internal facets.

[0075] According to some embodiments of the system, as part of calculating the deviation from parallelism, the deviation from parallelism of the internal facets, the deviation from two or more internal facets, the deviation relative to a reference internal facet, and the deviation from two or more internal facets are calculated.

[0076] According to some embodiments of the system, the first surface of the FOE is coated with an anti-reflective coating.

[0077] According to some embodiments of the system, the optical setup includes an autocollimator configured to generate a first plurality of light beams and to focus a second plurality of light beams onto a photosensing component.

[0078] According to some embodiments of the system, the second plurality of light beams include light beams that pass through a first surface of the sample and are returned from the sample via the FOE.

[0079] According to some embodiments of the system, the sample includes an outer, flat second surface opposite a first surface of the sample. The returned light beam is reflected from the second surface of the sample before it exits the sample through the first surface of the sample.

[0080] According to some embodiments of the method, the internal facets of the sample are perpendicular to the first surface of the sample. The second surface of the sample is parallel to the first surface of the sample.

[0081] According to some embodiments of the system, adjacent internal facets of the sample are spaced at regular intervals. The first tilt angle is equal to approximately (90° - arctan(2d1 / d2)), where d1 is the distance between the first surface and the second surface of the sample, and d2 is the distance between adjacent internal facets of the sample.

[0082] According to some embodiments of the system, the first tilt angle is such that the ratio of the power of the second plurality of light beams to the power of the first plurality of light beams is approximately maximized.

[0083] According to some embodiments of the system, the sample includes an outer, flat second surface opposite to the first surface of the sample. The second plurality of light beams include light beams that exit the sample through the second surface of the sample.

[0084] According to some embodiments of the system, the system further includes a second optical element (SOE). The SOE is approximately n s It has a refractive index equal to . The SOE includes an outer, flat first surface and an outer, flat second surface. The second surface of the SOE is opposite the first surface of the SOE and is inclined at a second acute angle with respect to the first surface of the SOE. The optical setup is additionally configured to allow positioning of the sample and / or the SOE such that the second surface of the SOE is adjacent to the second surface of the sample. According to some such embodiments, the SOE is n s It has a refractive index equal to .

[0085] According to some embodiments of the system, the second plurality of light beams include light beams that exit the sample through a second surface of the sample, pass through the SOE, and then exit the SOE through a first surface of the SOE.

[0086] According to some embodiments of the system, the optical setup is further configured to position the sample and / or SOE such that the second surface of the SOE is parallel to the second surface of the sample.

[0087] According to some embodiments of the system, the optical setup is further configured to allow positioning of the sample and / or SOE such that a first region on the first surface of the sample is in full contact with the second surface of the FOE, and a second region of the sample is in full contact with the second surface of the SOE. The first and second regions are defined by sections of the sample including internal facets. The second region is opposite the first region.

[0088] According to some embodiments of the system, the second tilt angle is approximately equal to the first tilt angle such that each of the second plurality of light beams exits from the SOE in a direction approximately normal to the first surface of the SOE. According to some such embodiments, the second tilt angle is equal to the first tilt angle.

[0089] According to some embodiments of the system, the internal facet of the sample is perpendicular to the first surface of the sample, the second surface of the sample is parallel to the first surface of the sample, and the adjacent internal facets of the sample are spaced apart at regular intervals. Each of the first tilt angle and the second tilt angle is equal to approximately (90° - arctan(d1 / d2)). d1 is the distance between the first surface of the sample and the second surface of the sample. d2 is the distance between adjacent internal facets of the sample.

[0090] According to some embodiments of the system, the SOE is a prism. According to some such embodiments, the SOE is a triangular prism.

[0091] According to some embodiments of the system, the first surface of the SOE is coated with an anti-reflection coating.

[0092] Certain embodiments of the present disclosure may include some or all of the above advantages, or may include none of them. One or more other technical advantages may be readily apparent to those skilled in the art from the drawings, the specification, and the claims included in this application. Further, although specific advantages are listed above, various embodiments may include all or some of the listed advantages, or may include none of them.

[0093] Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the technical field to which this disclosure pertains. In case of conflict, including definitions, this patent specification shall prevail. As used herein, the indefinite articles "a" and "an" mean "at least one" or "one or more" unless the context clearly dictates otherwise.

[0094] Unless otherwise specified, as will be apparent from the present disclosure, according to some embodiments, terms such as "process", "calculate", "operate", "determine", "estimate", "evaluate", or "measure" may refer to the act and / or process of a computer or computing system, or a similar electronic computing device that manipulates and / or transforms data represented as a physical (e.g., electronic) quantity within a register and / or memory of the computing system into other data similarly represented as a physical quantity within a memory, register, or other such information storage, transmission, or display device of the computing system.

[0095] Embodiments of the present disclosure may include an apparatus for performing operations herein. The apparatus may be specially constructed for the desired purpose or may include a general-purpose computer selectively activated or reconfigured by a computer program stored in the computer. Such a computer program may be stored in a computer-readable storage medium, such as, but not limited to, a floppy disk, optical disk, CD-ROM, magneto-optical disk, read-only memory (ROM), random access memory (RAM), electrically programmable read-only memory (EPROM), electrically erasable and programmable read-only memory (EEPROM), magnetic or optical card, or any other type of medium suitable for storing electronic instructions and capable of being coupled to a computer system bus.

[0096] The processes and displays presented herein are not inherently related to any particular computer or other apparatus. Various general-purpose systems may be used with programs in accordance with the teachings herein, or it may be convenient to construct a more specialized apparatus to perform the desired method. The desired structure for various such systems will be apparent from the following description. Also, in the description of embodiments of the present disclosure, no reference is made to any particular programming language. It will be understood that various programming languages may be used to implement the teachings of the present disclosure as described herein.

[0097] Aspects of this disclosure may be described in the general context of computer executable instructions, such as program modules, that are executed by a computer. Generally, a program module includes routines, programs, objects, components, and data structures that perform a particular task or implement a particular abstract data type. The disclosed embodiments may also be implemented in a distributed computing environment in which tasks are performed by remote processing devices linked over a communication network. In a distributed computing environment, program modules may reside on both local and remote computer storage media, including memory storage devices. [Brief explanation of the drawing]

[0098] Several embodiments of this disclosure will be described with reference to the accompanying drawings. The description, along with the drawings, will make it clear to those skilled in the art how some embodiments may be carried out. The drawings are for illustrative purposes only and do not attempt to show structural details of the embodiments in more detail than necessary for a fundamental understanding of this 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 to different scales. In particular, the scale of some objects may be significantly exaggerated compared to other objects in the same drawing. In the diagram,

[0099] [Figure 1A] Several embodiments of an optics-based system for measuring the internal facets of a sample, and a sample mounted on the system, are schematically described. [Figure 1B] This is an enlarged cross-sectional view of a section of the sample in Figure 1A, according to several embodiments. [Figure 1C] Figure 1A is an enlarged perspective view of a section of the sample according to several embodiments. [Figure 1D]Figure 1A schematically depicts the system in operation during sample inspection, according to several embodiments. [Figure 1E] Several enlarged views of Figure 1D are provided according to several embodiments. [Figure 2A] Figure 1A schematically depicts a spot on the photosensitive surface of the image sensor, acquired as part of a sample inspection according to several embodiments. [Figure 2B] Figure 1A schematically depicts a spot on the photosensitive surface of the image sensor, acquired as part of a sample inspection according to several embodiments. [Figure 3] A schematic diagram of an optics-based system for measuring the internal facets of a sample, corresponding to a specific embodiment of the system shown in Figure 1A, is provided. [Figure 4] Figure 3 schematically depicts spots on the photosensitive surface of the image sensor of the system, acquired as part of sample inspection in several embodiments. [Figure 5] This diagram schematically depicts several components of an optics-based system for measuring the internal facets of a sample, corresponding to a specific embodiment of the system shown in Figure 1A, with the sample attached. [Figure 6A] Several embodiments of an optics-based system for measuring the internal facets of a sample, and a sample mounted on the system, are schematically described. [Figure 6B] This is an enlarged cross-sectional view of a section of the sample in Figure 6A, according to several embodiments. [Figure 7] A schematic diagram of an optics-based system for measuring the internal facets of a sample, corresponding to a specific embodiment of the system shown in Figure 6A, is provided. [Figure 8] A flowchart of an optics-based method for measuring the internal facets of a sample, according to several embodiments, is presented. [Figure 9] A flowchart of an optics-based method for measuring the internal facets of a sample, corresponding to a specific embodiment of the method shown in Figure 8, is presented. [Figure 10] Present a flowchart of an optical-based method for measuring the internal facets of a sample corresponding to a specific embodiment of the method of FIG. 8. **Embodiments for Carrying Out the Invention**

[0100] The principles, uses, and implementations of the teachings disclosed in this application can be better understood by referring to the accompanying specification and drawings. Those skilled in the art who have examined the specification and drawings of this application will be able to implement the teachings of this specification without undue effort or experimentation. In the figures, the same reference numbers refer to the same parts throughout.

[0101] In the specification and claims of this application, the words "comprising" and "having," and their forms, are not limited to the components in the list to which these words may be associated.

[0102] As used in this application, the term "about" can be used to specify a value of a quantity or parameter (e.g., the length of an element) within a range of continuous values near (and including) a given (stated) value. According to some embodiments, "about" can specify a value of a parameter to be 80% - 120% of a given value. For example, the description "the length of the element is about 1 m" is equivalent to the description "the length of the element is 0.8 m - 1.2 m." According to some embodiments, "about" can specify a value of a parameter to be 90% - 110% of a given value. According to some embodiments, "about" can specify a value of a parameter to be 95% - 105% of a given value. In particular, it should be understood that the terms "substantially equal" and "substantially equivalent" also encompass exact equivalence.

[0103] As used in this specification, according to some embodiments, the terms "substantially" and "about" may be synonymous.

[0104] For the sake of simplicity, some of the drawings use a three-dimensional Cartesian coordinate system. Note that the orientation of the coordinate system relative to the depicted objects may differ from drawing to drawing. Also, the symbols...

number

number

[0105] In the diagram, optional elements and optional stages (in the flowchart) are depicted with dashed lines.

[0106] Throughout the specification, vectors are lowercase, bold upright characters (e.g., symbol 1).

[0107] It is represented as TIFF0007881224000017.tif33).

[0108] The explanation includes quantitative relationships between parameters in the form of equations. Therefore, to make the explanation clearer, throughout the explanation, certain symbols are used exclusively to indicate specific types of parameters and / or quantities. Vector symbol 2

[0109] JPEG0007881224000018.jpg57 (including superscripts and / or subscripts) represents a two-dimensional vector specifying the coordinates of a spot (e.g., on a component). The Greek letter "ε" (including superscripts and / or subscripts) represents an angle or magnitude of an angle between planes. More specifically, the Greek letter "ε" is used to represent the deviation from parallelism, or the magnitude of the deviation from parallelism, between pairs of internal facets of a sample. The Greek letter "δ" (including superscripts and / or subscripts) represents an angle or 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 light beams. s " indicates the refractive index of the sample examined using the disclosed system and / or method. "f" represents the focal length of the focusing lens or lens assembly used to focus the light beam returned onto the photosensitive component included in the disclosed system, which is used to examine the sample and / or used as part of the disclosed method used to examine the sample. Thus, symbol 3

[0110] TIFF0007881224000019.tif33, ε, δ, n s , and f (and angle symbols "μ", "σ", and "Δ") should not be considered associated with the specific embodiment in which those symbols are first introduced in the text. In particular, values, ranges of values, and / or symbols 4 in the context of one embodiment

[0111] TIFF0007881224000020.tif33 and parameters ε, δ, n s The constraints on the values ​​of f (and the parameters μ, σ, and Δ) (components) are not necessarily carried over to other embodiments.

[0112] Throughout this specification, flat surfaces within a three-dimensional element (such as a flat boundary between two parts of a three-dimensional element or a flat internal layer of material incorporated within a three-dimensional element) are referred to as "internal facets."

[0113] In this specification, when an object is intended, in terms of design and manufacture, to exhibit (i.e., be characterized by) a characteristic such as the angle of inclination between the flat surfaces of a sample, the object may be said to "nominally" exhibit that characteristic, although due to manufacturing tolerances, the characteristic may only be exhibited imperfectly.

[0114] system According to some embodiments, an optics-based system is provided for measuring a sample (e.g., a one-dimensional or two-dimensional reflective waveguide) comprising a substrate characterized by a uniform refractive index (making up the majority of the sample) and two or more internal facets embedded within the substrate, nominally parallel and substantially perpendicular to at least the outer (first) surface of the sample (e.g., the main surface of the reflective waveguide). The system may be used to implement the optics-based method (for verifying the parallelism between the internal facets of the sample) shown in Figure 8.

[0115] The system includes (at least one) optical element (e.g., a prism), a light source, a light-sensing component, and optionally, an optical setup including an optical instrument. The optical instrument includes at least a collimator lens or collimator lens assembly configured to collimate the light produced by the light source, thereby preparing a first set of light beams.

[0116] The optical element has a refractive index approximately equal to that of the substrate and includes an outer, flat first surface and an outer, flat second surface opposite it. The second surface of the optical element is inclined at an acute (first) inclination angle with respect to the first surface of the optical element. The optical setup is configured to allow the sample and / or the optical element to be positioned such that (i) the second surface of the optical element is adjacent to the first surface of the sample, and (ii) when positioned in this manner (i.e., when the positioned second surface of the optical element is adjacent to the first surface of the sample), a plurality of first light beams that can be generated by the light source collide with the first surface of the optical element in a direction approximately normal to it.

[0117] The optical instrument may include a focusing lens or focusing lens assembly configured to focus a second plurality of light beams onto a photosensing component in order to enable the measurement of angular deviations between light beams in the second plurality of light beams. The second plurality of light beams include light beams that travel through (i.e., through) the optical element, are transmitted into the sample, are reflected once from the internal facets, and then exit the sample. Based on the (measured) angular deviations between the second plurality of light beams, deviations from the parallelism between the internal facets can be calculated.

[0118] According to some embodiments, such as those described in the following descriptions of Figures 1A to 5, following reflection from an internal facet, the reflected light beam is reflected from a second surface of the sample opposite to the first surface of the sample. These double-reflected (i.e., reflected twice within the sample) light beams pass through the sample via the first surface of the sample and the second surface of the optical element, and then pass through the optical element into the optical element, exiting the optical element via the first surface of the optical element (e.g., being refracted) (thus obtaining a second set of light beams).

[0119] According to some embodiments, such as those described below in the description of Figures 6A-7, the system includes a second optical element (SOE) which may be similar to a first optical element (FOE). The SOE has a refractive index approximately equal to the refractive index of the substrate and includes an outer, flat first surface and an outer, flat second surface. The second surface of the SOE is inclined at a second, acute angle of inclination with respect to the first surface of the SOE. The optical setup is additionally configured to allow positioning of the sample and / or SOE such that the second surface of the SOE is adjacent to the second surface of the sample. Following reflection from the internal facets, the reflected light beam (i) passes from the sample into the second optical element via the second surface of the sample facing the first surface of the sample and the second surface of the SOE, and (ii) exits the SOE via the first surface of the SOE (e.g., is refracted) (thus obtaining a second plurality of light beams).

[0120] According to some embodiments, where the second surface of the sample is parallel to the first surface of the sample (for example, when the first and second surfaces of the sample are the main surfaces of the reflection waveguide), the second tilt angle may be approximately equal to the first tilt angle, thereby ensuring that the second plurality of light beams exit from the SOE in a direction approximately normal to the first surface of the SOE (which may help reduce dispersion).

[0121] Figure 1A schematically illustrates a flowchart of an optics-based method 100 for measuring the internal facets of a sample, according to several embodiments. The optics-based system 100 is configured to verify the parallelism between the internal facets of the sample. More specifically, Figure 1A presents a cross-sectional side view of the system 100 and sample 10 according to several embodiments. (It should be understood that sample 10 does not constitute part of the system 100.)

[0122] Sample 10 includes a light-transmitting substrate 12 and two or more internal facets 14 embedded in the substrate 12. Sample 10 further includes an outer first surface 16a (also referred to as the “first surface of the sample”) and an outer second surface 16b (also referred to as the “second surface of the sample”). The second surface of the sample 16b faces the first surface of the sample 16a. Each of the first surface of the sample 16a and the second surface of the sample 16b may be flat. According to some embodiments, the second surface of the sample 16b is parallel to the first surface of the sample 16a, as depicted in Figures 1A to 1E. According to some embodiments, each of the internal facets 14 constitutes a thin semi-reflective or reflective layer embedded in the substrate 12. According to some embodiments, one or more of the internal facets 14 may be thin films or partial mirrors. According to some embodiments, one or more of the internal facets 14 may be made of or include glass and / or dielectric materials. According to some embodiments, the substrate 12 may be a one-dimensional or two-dimensional reflective waveguide (also referred to as a "geometric waveguide"). According to some such embodiments, the first surface 16a and the second surface 16b of the sample constitute the main surface of the waveguide. According to some embodiments, the sample 12 may be made of glass, crystal, or transparent polymer.

[0123] The sample section 18 of sample 10 corresponds to the portion (e.g., segment) of substrate 12 where the internal facet 14 is disposed (while the section of sample 10 complementary to sample section 18 may lack any of the internal facets 14). Also, referring to FIGS. 1B and 1C, FIG. 1B provides an enlarged view of sample section 18 according to some embodiments. As a non-limiting example intended to facilitate the explanation by making it more specific, in FIGS. 1A and 1B, the internal facet 14 includes three internal facets: a first internal facet 14a, a second internal facet 14b, and a third internal facet 14c, and the second internal facet 14b is shown to be disposed between the first internal facet 14a and the third internal facet 14c. Those skilled in the art will readily recognize that the three internal facet case encompasses requirements for any number of internal facets (e.g., 4, 5, 10, or 11 or more). FIG. 1C provides a perspective view of an end 15 of sample section 18 including the first internal facet 14a and the second internal facet 14b according to some embodiments.

[0124] The internal facets 14 are nominally parallel. That is, according to the intended design of sample 10, the internal facets 14 are parallel. In practice, due to manufacturing imperfections, the internal facets 14 typically cannot exhibit perfect parallelism. According to some embodiments, each of the internal facets 14 has a nominal angle μ nom that is approximately equal to 90° (extending on a plane parallel to the zx plane) and is nominally inclined with respect to the first surface 16a of the sample. According to some such embodiments, also as depicted in FIGS. 1A - 1E, the internal facets 14 are nominally perpendicular to the first surface 16a of the sample (and, in embodiments where the second surface 16b of the sample is parallel to the first surface 16a of the sample, the second surface 16b of the sample), that is, μ nom = 90°. In practice, each of the internal facets 14 has a nominal angle μ nomThey can be oriented to their respective actual angles, which are slightly different from the first internal facet 14a, the second internal facet 14b, and the third internal facet 14c are oriented to a first angle μ1, a second angle μ2, and a third angle μ3 with respect to the first surface 16a of the sample, respectively.

[0125] Due to imperfections in the manufacturing process, the actual angle μ i (i=1, 2, 3) may differ from each other not only in magnitude but also in their respective angle-forming planes, and / or in nominal angle μ nom Please note that this may differ. For example, μ nom Given that μ1 is formed on a first plane parallel to the zx plane, μ1 can be formed on a second plane inclined with respect to the first plane. Similarly, μ2 can be formed on a third plane inclined with respect to the first and / or second planes. In other words, symbol 5

[0126] TIFF0007881224000021.tif66 symbol 6

[0127] TIFF0007881224000022.tif56 and symbol 7

[0128] TIFF0007881224000023.tif43(Symbol 8)

[0129] TIFF0007881224000024.tif43 and symbol 9

[0130] As shown in Figure 1C, TIFF0007881224000025.tif43 represents the unit vectors in the normal direction for the first internal facet 14a, the second internal facet 14b, and the third internal facet 14c, respectively, most generally, symbol 10

[0131] JPEG0007881224000026.jpg655

[0132] "Pitch of the internal facet", as used herein, refers to the angle by which the internal facet rotates about the y-axis relative to its nominal orientation. "Roll of the internal facet" refers to the angle by which the internal facet rotates about the x-axis relative to its nominal orientation.

[0133] The nominal orientation of the internal facet 14 is the unit vector symbol 11 in FIG. 1C

[0134] as indicated by TIFF0007881224000027.tif43 (i.e., symbol 12 in the absence of processing defects

[0135] TIFF0007881224000028.tif625. In accordance with the choice of the coordinate system in FIG. 1C, symbol 13

[0136] TIFF0007881224000029.tif43 indicates the direction along the direction defined by the z-axis. The first plane 17a (depicted by the dashed line) shows the nominal position of the first internal facet 14a. Shown on the first plane 17a are a x and a y which are, respectively,

Number

[0137] TIFF0007881224000031.tif43's non-vanishing x and y components (i.e., a x and a y ) are shown to be different from the first plane 17a in both pitch and roll. The second plane 17b (depicted by the dashed line) shows the nominal position of the second internal facet 14b. Shown on the second plane 17b are b x and b y which are, respectively,

Number

[0138] The non-vanished x and y components of TIFF0007881224000033.tif43 (i.e., b x and b y As revealed by ), it is shown that the second plane 17b is different in both pitch and roll. The first internal facet 14a and the second internal facet 14b are shown to be different from each other in both pitch and roll (i.e., in Figure 1C, b x >a x and b y >a y ).

[0139] Each of the first surface 16a and the second surface 16b of the sample extends from the first end 11a to the second end 11b of the sample 10. The sample section 18 defines a region 13 on the first surface 16a of the sample, positioned above (all) of the internal facets 14.

[0140] According to some embodiments, the system 100 includes an optical element 102 that is light-transmitting, and an optical setup 104. The system 100 may further include a controller 108 that is functionally associated with the optical setup 104 and configured to control the operation of the optical setup 104. According to some embodiments, as depicted in Figure 1A, the optical setup 104 includes an illumination and collection assembly (ICA) 112 and a holding infrastructure 114 for mounting a sample 10 on the holding infrastructure 114 itself. According to some embodiments, as detailed below, the holding infrastructure 114 may include an orientation infrastructure configured to allow the orientation of the sample 10 to be set in a controllable manner. The ICA 112 includes a light source 122 (or more light sources) and a light-sensing component 124. According to some embodiments, the light-sensing component 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 component 124 may be a camera. Alternatively, according to some embodiments, the light-sensing component 124 may be an eyepiece assembly configured for visual determination (i.e., determination by the eye) of the deviation between light rays focused to the eyepiece assembly. According to some embodiments, the ICA 112 may further include an optical instrument 128 whose function is described below.

[0141] The optical element 102 includes a substrate 132, the substrate 132 constituting the majority of the optical element 102, and having a refractive index (e.g., n) approximately the same as the substrate 12 of sample 10. s Greater than -0.02, n sIt is made of a material having a refractive index less than +0.02. According to some such embodiments, the substrate 132 is made of a material having the same refractive index as the substrate 12. The optical element 102 further includes an outer first surface 134a (e.g., the first surface of the outer substrate 132) and an outer second surface 134b (e.g., the second surface of the outer substrate 132) opposite to it. According to some embodiments, as depicted in Figure 1A, the first surface 134a of the optical element is flat. According to some such embodiments, as depicted in Figure 1A, the second surface 134b of the optical element is also flat and inclined with respect to the first surface 134a of the optical element. According to some embodiments, the optical element 102 is a prism. According to some such embodiments, the prism may be a triangular prism.

[0142] According to several embodiments, in particular embodiments in which (i) the first surface 16a and the second surface 16b of the sample are parallel, (ii) the internal facet 14 is nominally perpendicular to each of the first surface 16a and the second surface 16b of the sample, and (iii) adjacent internal facets are spaced apart at regular intervals, the second surface 134b of the optical element may be inclined with respect to the first surface 134a of the optical element at an inclination angle σ, where the inclination angle σ is formed parallel to the zx plane and equal to (90° - arctan(2d1 / d2)), i.e., the inclination angle σ is equal to 90 degrees minus arctan(2d1 / d2), where d1 is the distance between the first surface 16a and the second surface 16b of the sample, and s2 is the distance between adjacent internal facets (e.g., internal facets 14a and 14b, internal facets 14b and 14c). Distances d1 and d2 are indicated by double-headed dashed arrows in Figure 1B. The reasons for selecting the inclination angles as described above will be explained below in the description of Figures 1D and 1E. ICA112 is configured to output a collimated light beam (as shown in Figures 1C and 1D), which is generated by light source 122 and optionally manipulated (e.g., collimated) by optical instrument 128. According to some embodiments, optical instrument 128 may include a collimating lens or a collimating lens assembly (not shown). The optical elements 102 and ICA112 (more precisely, the illumination component of ICA112) may be configured such that the light beam output by ICA112 collides with the first surface 134a of the optical element normal to the first surface 134a of the optical element, or at least nearly normal (e.g., within 1°, 1.5°, or possibly 2° from the normal incidence).

[0143] The optical element 102 and the optical setup 104 may be configured to ensure that the incident light beam is reflected at best negligibly from the first surface 134a of the optical element, or that any portion directly reflected from the first surface 134a of the optical element is distinguishable from the reflected light beam that passes through the optical element 102 and sample 10, is reflected from the internal facets 14, and re-passes through the optical element 102. As described below in the description of Figures 1C and 1D, deviations from parallelism between the internal facets 14 are calculated based on sensed data of the reflected light beam (i.e., by measuring one or more parameters that characterize each of the reflected light beams). According to some embodiments, negligible reflection of the incident light beam from the first surface 134a of the optical element can be achieved by coating the first surface 134a of the optical element with an anti-reflective coating (if it is not already coated). The coating may be permanent or temporary.

[0144] To avoid obscuring the viewability of Figures 1D and 1E, the light beam reflected from the first surface 134a of the optical element is not shown.

[0145] Alternatively, according to some embodiments, the incident light beam may be slightly tilted by an angle Δ with respect to the normal to the first surface 134a of the optical element, so as to ensure that the propagation direction of light directly reflected from the first surface 134a of the optical element is sufficiently different from each of the propagation directions of the returned light beam (when it exits the optical element 102 after reflection from the internal facet 14). In such embodiments, the incident light beam may be selected to be monochromatic to minimize dispersion upon transmission to the optical element 102. According to some embodiments, the angle is 0.3°≦|Δ|≦0.5°, 0.2°≦|Δ|≦0.7°, or possibly 0.1°≦|Δ|≦1°. Each possibility corresponds to a different embodiment.

[0146] According to some embodiments, the light source 122 may be configured to produce a monochromatic light beam (so that the light beam output by the ICA 112 is monochromatic). According to some embodiments, the light source 122 may be a laser source (and therefore the light beam output by the ICA 112 is a laser beam). According to some embodiments where the light source 122 is a laser source, the ICA 112 may be configured to output a collimated, expanded laser beam. According to some such embodiments, the optical instrument 128 may include a beam expander (not shown) configured to increase the diameter of the laser beam. According to some embodiments, such as an embodiment where sample 10 is a one-dimensional waveguide, the diameter of the expanded laser beam (e.g., the maximum diameter when the cross-section of the expanded laser beam defines an ellipse) may be approximately equal to the longitudinal dimension of region 13. According to some embodiments, such as an embodiment where sample 10 is a two-dimensional waveguide, the cross-sectional area of ​​the expanded laser beam may be approximately equal in size to the cross-sectional area of ​​region 13.

[0147] It should be noted that a multicolor incident light beam can be used in embodiments in which the first surface 134a of the optical element is coated with an anti-reflective coating, insofar as the incident light beam is projected in the direction normal to the first surface 134a of the optical element (thereby preventing or at least significantly reducing dispersion).

[0148] According to some embodiments, at least a portion of the light source 122, the light sensing component 124, and the optical instrument 128 may constitute an autocollimator or a component of 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.

[0149] According to some embodiments, the optical instrument 128 may further include a translationable slit optical mask or aperture optical mask (such as the translationable slit optical mask shown in Figure 2, not shown) configured to control the incident position of a light beam (e.g., a laser beam) on the first surface 134a of the optical element, thereby enabling separate inspection of each of the internal facets 14. Alternatively, according to some embodiments, the optical instrument 128 may further include a plurality of shutters configured to enable (allow) separate inspection of each of the internal facets 14.

[0150] According to some embodiments, the holding infrastructure 114 may be configured to allow controllable setting of the orientation between the sample 10 and the optical element 102. In particular, the holding infrastructure 114 may be configured to allow orientation of the sample 10 and / or the optical element 102 such that the first surface 16a of the sample is adjacent to and parallel to the second surface 134b of the optical element. According to some embodiments, the holding infrastructure 114 may be further configured to orient the optical element 102 such that the incident light beam output by the ICA 112 collides with the first surface 134a of the optical element in the direction normal to (i.e., perpendicular to) the optical element. As a non-limiting example, according to some embodiments, the holding infrastructure 114 may include an oriented stage assembly 138 or an oriented stage (e.g., a biaxial stage).

[0151] The stage assembly 138 is configured to allow a sample, such as sample 10, to be mounted on it, and to allow adjustment of the pitch angle and / or roll angle of the sample. According to some embodiments, the stage assembly 138 may be configured to allow manipulation of a sample mounted on the stage assembly 138 in each of the six degrees of freedom. According to some embodiments, the stage assembly 138 may include two goniometers (not shown in Figure 1A, such as the goniometer depicted in Figure 5), namely a pitch goniometer and a roll goniometer, one of which is positioned on top of the other. According to some such embodiments, the stage assembly 138 may include a platform (not shown in Figure 1A, such as the inclined platform depicted in Figure 5) that is (i) positioned on the upper of the two goniometers and (ii) configured on which sample 10 is placed. In some such embodiments, an optical element 102 may be positioned on and supported by sample 10. Alternatively, according to some embodiments, the retaining infrastructure 114 may include an oriented retaining gear (not shown) configured to hold and controllably orient the optical element 102. According to some embodiments, the retaining infrastructure 114 may be functionally associated with and configured to be controlled by a controller 108.

[0152] Referring also to Figures 1D and 1E, Figure 1D presents a cross-sectional side view of system 100 and sample 10 according to several embodiments, where sample 10 is being inspected by system 100. Figure 1E provides some enlarged views of Figure 1D, drawn by dashed line L. During operation, according to some embodiments, an enlarged and collimated incident light beam (not all numbered), indicated by arrow 105, is projected onto the first surface 134a of the optical element. According to some embodiments, in particular, embodiments in which the first surface 134a of the optical element is coated with an anti-reflective coating, the incident light beam can be projected normal to the first surface 134a of the optical element.

[0153] The incident light beam (or at least a portion thereof) is transmitted through the first surface 134a of the optical element to the optical element 102, thereby obtaining a transmitted light beam. The transmitted light beam is indicated by arrows 115 (not all of which are numbered). The transmitted light beam travels across the optical element 102, intersects (i.e., passes through) the sample 10 via the second surface 134b of the optical element and the first surface 16a of the sample, and propagates toward the internal facet 14. The transmitted light beam is reflected from the internal facet 14 toward the second surface 16b of the sample.

[0154] More specifically, since the internal facets 14 may differ slightly from each other in their respective orientations, the transmitted light beam may be reflected from each of the internal facets 14 at slightly different angles. Thus, multiple reflected light beams with slightly different propagation directions may be obtained. The first reflected light beam, corresponding to the portion of the transmitted light beam reflected from the first internal facet 14a, is indicated by arrow 125a. The second reflected light beam, corresponding to the portion of the transmitted light beam reflected from the second internal facet 14b, is indicated by arrow 125b. The third reflected light beam, corresponding to the portion of the transmitted light beam reflected from the third internal facet 14c, is indicated by arrow 125c.

[0155] As indicated by arrows 135a, 135b, and 135c, the reflected light beam is reflected (again) from the second surface 16b of the sample, exits the sample 10 via the first surface 16a of the sample, and re-enters (i.e., is transmitted) into the optical element 102 via the second surface 134b of the optical element. Following re-entry into the optical element 102, the double-reflected (i.e., reflected twice within the sample 10) light beam travels to the first surface 134a of the optical element, exits the optical element 102 (e.g., is refracted), thereby obtaining multiple reflected light beams. The first reflected light beam resulting from the refraction of the first double-reflected light beam (indicated by arrow 135a) from the optical element 102 is indicated by arrow 145a. The second reflected light beam resulting from the refraction of the second double-reflected light beam (indicated by arrow 135b) from the optical element 102 is indicated by arrow 145b. The third reflected light beam, resulting from the refraction of the third double-reflected light beam (indicated by arrow 135c) from the optical element 102, is indicated by arrow 145c. The reflected light beam propagates toward the ICA 112 and is focused by the optical instrument 128 on the photosensing component 124.

[0156] The light-sensing component 124 is configured to allow the angular deviation between pairs of reflected light beams focused on the light-sensing component 124 to be obtained from the sensed data of the light-sensing component 124 (i.e., measurement data of the reflected light beams acquired by the light-sensing component 124, or measurement data of the reflected light beams acquired using the light-sensing component 124). From the angular deviation, the magnitude of the deviation from the parallelism between the internal facets 14 can be estimated, for example, as described in the following descriptions of Figures 2A and 2B.

[0157] According to some embodiments, the tilt angle σ is equal to (90° - arctan(2d1 / d2)). As is evident by examining Figures 1D and 1E, selecting σ as described above ensures that all rays in the reflected light beam are transmitted (or at least partially transmitted) to the optical element 102 after being reflected from the second surface 16b of the sample, without being reflected again by any of the internal facets 14. Thus, selecting σ as described above can reduce losses and thereby improve the detection of the reflected light beam (for example, by ensuring that the reflected light beam forms a bright spot on the photosensitive surface of the image sensor). According to some embodiments, the tilt angle σ is equal to approximately (90° - arctan(2d1 / d2)).

[0158] According to some embodiments in which the first surface 134a of the optical element is not coated with an anti-reflective coating, the light projected onto the first surface 134a of the optical element is reflected from the first surface 134a of the optical element in a second portion, in addition to being transmitted into the optical element 102 in a first portion. In such embodiments, the incident light beam may be projected at a small (non-disappearing) angle of incidence (relative to the first surface 134a of the optical element) to ensure that the reflected light beam (i.e., the light beam reflected from the internal facet 14 and then returned through the optical element 102) is distinguishable from the portion of the incident light beam reflected from the first surface 134a of the optical element. Thus, in embodiments in which the light sensing component 124 is an image sensor, as depicted in Figure 2B and detailed below, the spots formed by the reflected light beam are typically clustered (i.e., concentrated), while the spots formed by the directly reflected portion of the incident light beam are significantly out of cluster.

[0159] According to some embodiments, and also as depicted in Figures 1A, 1D, and 1E, the optical element 102 can be positioned on the sample 10 such that the second surface 134b of the optical element is in contact with all or at least all of the first surface 16a of the sample (and can also be optionally supported by the sample 10). In such embodiments, the transmitted light beam passes directly from the optical element 102 to the sample 10, and the reflected light beam passes directly from the sample 10 into the optical element 102.

[0160] In some embodiments, the second surface 134b of the optical element is not in contact with the first surface 16a of the sample. If the incident light beam is not monochromatic, the space between the optical element 102 and the sample 10 (unless filled as described below) may cause dispersion when the transmitted light beam exits the optical element 102 through the second surface 134b of the optical element. In embodiments where the second surface 134b of the optical element and the first surface 16a of the sample are parallel and well polished (and the refractive index of the optical element 102 is equal to the refractive index of the substrate 12), light beams of different frequencies are realigned when they enter the sample 10. Otherwise, to avoid or at least mitigate dispersion, according to some embodiments, the light source 122 may be configured to produce a monochromatic light beam (e.g., a laser beam), and / or a refractive index matching shape-fitting interface (not shown) may be inserted between the sample 10 and the optical element 102 (so as to be sealed between the first surface 16a of the sample and the second surface 134b of the optical element). The shape-conforming interface has a refractive index (e.g., n) that is approximately the same as that of sample 10. s Greater than -0.02, n sIt may have a value less than +0.02. The shape-fitting interface may be a liquid, gel, or paste characterized by surface tension and / or adhesive properties, such as maintaining its integrity and position when encapsulated in a narrow space. According to some embodiments, the shape-fitting interface may be made of a malleable material. Thus, the light beam propagating through the optical element 102, the shape-fitting interface, and the sample 10 substantially maintains its propagation direction as it travels from the optical element 102 into the shape-fitting interface and from the shape-fitting interface into the sample 10.

[0161] According to some embodiments, the shape-matching interface (as described above) can also be used to prevent total internal reflection of the double-reflected light beam (i.e., in embodiments where the inclination angle σ is such that the double-reflected light beam can strike the first surface 134a of the optical element at an incident angle greater than the critical angle defined by the substrate 12 and the air).

[0162] Referring also to Figure 2A, Figure 2A schematically depicts a spot 201 on the photosensitive surface 244 of the image sensor 224 according to several embodiments of the system 100, in which (i) the first surface 134a of the optical element is coated with an anti-reflective coating, and (ii) the ICA 112 includes an autocollimator. The autocollimator corresponds to a specific embodiment of the light sensing component 124, or includes the image sensor 224 included in the light sensing component 124. The spot 201 includes a first spot 201', a second spot 201'', and a third spot 201''' according to several embodiments. The spot 201 is formed by the reflected light beam (indicated by arrow 145 in Figures 1D and 1E). According to some embodiments, it may not be possible to attribute the spot to a particular reflected light beam. (Unless each of the internal facets is examined separately, for example, as described below in the descriptions of Figures 3 and 4, or optionally, if additional information is available that uniquely characterizes each of the internal facets, for example, if the internal facets differ from one another by reflectance design). In particular, it should be understood that the first spot 201' may be formed by a first reflected light beam (induced by reflection from the first internal facet 14a), a second reflected light beam (induced by reflection from the second internal facet 14b), or a third reflected light beam (induced by reflection from the third internal facet 14c). Similarly, a second spot 201'' may be formed by any one of the returned light beams (but a different returned light beam from the one forming the first spot 201'), or a third spot 201'' may be formed by any one of the returned light beams (but a different returned light beam from each of the returned light beams forming the first spot 201' and the second spot 201''). However, as illustrated in the following example, information such as the average magnitude of the deviation from parallelism (also referred to as the average "radial deviation") and the maximum magnitude of the deviation from parallelism (also referred to as the maximum "radial deviation") can be extracted from the coordinates of spot 201.When used herein, the “radial deviation from parallelism” between internal facets generally refers to the quantum deviation of the deviation from parallelism, taking into account both pitch and roll deviations.

[0163] Two-dimensional vector symbol 16

[0164] TIFF0007881224000034.tif45=(u α,x ,u α,y ), symbol 17

[0165] TIFF0007881224000035.tif45=(u β,x ,u β,y ) and symbol 18

[0166] TIFF0007881224000036.tif45=(u γ,x ,u γ,y ) designates the positions of the first spot 201', the second spot 201'', and the third spot 201''', respectively. Note that according to some embodiments, the spot 201 is spatially expanded (i.e., not one-dimensional), and the vector symbol 19

[0167] JPEG0007881224000037.jpg728 may specify the center points (coordinates) of spot 201', second spot 201'', and third spot 201'''', respectively. According to some embodiments, the center points may be calculated by averaging over the coordinates of each pixel constituting the spot, weighted by the intensity of the pixels.

[0168] Unit vector symbol 20

[0169] TIFF0007881224000038.tif54 corresponds to the propagation direction of the reflected light beam that produces the first spot 201'. Unit vector symbol 21

[0170] TIFF0007881224000039.tif54 corresponds to the propagation direction of the reflected light beam that produces the second spot 201''. Unit vector symbol 22

[0171] TIFF0007881224000040.tif55 corresponds to the propagation direction of the reflected light beam that produces the third spot 201'''. Angular deviation δ γβ This is symbol 23

[0172] TIFF0007881224000041.tif55 and symbol 24

[0173] Corresponds to the magnitude of the angle formed during TIFF0007881224000042.tif54. Angular deviation δ αγ is symbol 25

[0174] TIFF0007881224000043.tif54 and symbol 26

[0175] Corresponds to the magnitude of the angle formed during TIFF0007881224000044.tif55. Angular deviation δ βα This is symbol 27

[0176] TIFF0007881224000045.tif54 and symbol 28

[0177] Corresponds to the magnitude of the angle formed during TIFF0007881224000046.tif54. Angular deviation δ γβ , δ αγ , and δ βα This is vector symbol 29

[0178] This can be inferred from JPEG0007881224000047.jpg625. Next, from the angular deviation, the deviation (magnitude) from the parallelism between internal facets can be inferred.

[0179] The coordinate system depicted in Figure 2A is assumed to coincide with the coordinate system depicted in Figure 1D, up to the possible translation of the origin. According to some embodiments in which a focusing lens with focal length f1 (not shown, e.g., a focusing lens of an autocollimator) is used to focus the reflected light beam onto an image sensor (e.g., an image sensor of an autocollimator), the magnitude of the angular deviation between the reflected light beams is related

number

number

number

[0180] Unit vector symbol 30

[0181] TIFF0007881224000051.tif45 corresponds to the normal of the internal facet to which the light beam that produces the first spot 201' is reflected. (Therefore, most commonly, the unit vector symbol 31

[0182] TIFF0007881224000052.tif45 may correspond to the normals for the first internal facet 14a, the second internal facet 14b, or the third internal facet 14c. Unit vector symbol 32

[0183] TIFF0007881224000053.tif55 corresponds to the normal of the internal facet to which the light beam that produces the second spot 201'' is reflected. Unit vector symbol 33

[0184] TIFF0007881224000054.tif55 corresponds to the normal of the internal facet to which the light beam that produces the third spot 201''' is reflected. Deviation ε γβ This is symbol 34

[0185] This corresponds to the magnitude of the angle formed between TIFF0007881224000055.tif615. Deviation ε αγ Symbol 35

[0186] This corresponds to the magnitude of the angle formed during TIFF0007881224000056.tif617. Deviation ε βα This is symbol 36

[0187] This corresponds to the magnitude of the angle formed between TIFF0007881224000057.tif616. (As will be apparent to those skilled in the art from Snell's Law), n s ·sin(2ε γβ ) = sin(δ γβ ),n s ·sin(2 αγ ) = sin(δ αγ ) and n s ·sin(2ε βα ) = sin(δ βα )

[0188] Equation max{ε γβ ,ε αγ ,ε βα The formula (ε) can be used to quantify the maximum radial deviation from parallelism. γβ +ε αγ +ε βα The mean radial deviation from the parallelism between internal facets can be quantified using ) / 3. Since none of the spots 201 are typically attributable to reflections from specific internal facets individually, the above formula is independent of the sign of the angular deviation.

[0189] Similarly (by selecting the coordinate system as depicted), the magnitude of the pitch deviation between internal facets (i.e., ε γβ,p , ε αγ,p , and ε βα,p ) are, respectively, the relation tan(δ γβ,p )=|u β,x -u γ,x | / f and n s ·sin(2ε γβ,p ) = sin(δγβ,p ), tan(δ αγ,p )=|u γ,x -u α,x | / f and n s ·sin(2ε αγ,p ) = sin(δ αγ,p ), and tan(δ βα,p )=|u α,x -u β,x | / f and n s ·sin(2ε βα,p ) = sin(δ βα,p ) can be calculated from the internal facet (i.e., ε γβ,r , ε αγ,r , ε βα,r The magnitude of the roll deviation between the two is related by the relationship tan(δ γβ,r )=|u β,y -u γ,y | / f and n s ·sin(2ε γβ,r ) = sin(δ γβ,r ), tan(δ αγ,r )=|u γ,y -u α,y | / f and n s ·sin(2ε αγ,r ) = sin(δ αγ,r ), and tan(δ βα,r )=|u α,y -u β,y | / f and n s ·sin(2ε βα,r ) = sin(δ βα,r ) can be calculated from δ. γβ,p and δ γβ,r These are, respectively, symbol 37

[0190] Corresponds to the pitch and roll size between TIFF0007881224000058.tif716. δ αγ,p and δ αγ,r These are, respectively, symbol 38

[0191] Corresponds to the pitch and roll size between TIFF0007881224000059.tif614. δ βα,p and δ βα,r These are, respectively, symbol 39

[0192] Corresponds to the pitch and roll magnitudes between TIFF0007881224000060.tif718. Formula max{ε γβ,p ,ε αγ,p ,ε βα,p} and max{ε γβ,r ,ε αγ,r ,ε βα,r The equations} can be used to quantify the maximum deviation (magnitude) in the pitch and roll between the internal surfaces 14, respectively. Equation (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 (magnitude) of pitch and roll between the internal facets 14, respectively.

[0193] Alternatively, according to some embodiments, the parallelism ε between internal facets 14 max The maximum deviation from is related to

number

[0194] According to some embodiments where the deviation from parallelism is sufficiently small, small-angle approximation can be used. Under small-angle approximation (when calculated in radians),

number

number

number

[0195] Referring also to Figure 2B, which schematically depicts spots 221 and 231 on the photosensitive surface 244 according to several embodiments of system 100, where the incident light beam is projected at a slight inclination with respect to the normal to the first surface 234a of the optical element, and the first surface 134a of the optical element is not coated with an anti-reflective coating (ICA 112 includes an autocollimator with an image sensor). Spot 231 is formed by a portion of the incident light beam, which is directly reflected from the first surface 134a of the optical element (i.e., this portion of the incident light beam is specularly reflected from the first surface 134a of the optical element).

[0196] Two-dimensional vector symbol 40

[0197] TIFF0007881224000065.tif33=(v x ,v y ) specifies the coordinates of spot 231 (for example, the coordinates of the center point of the spot). Two-dimensional vector = symbol 41

[0198] TIFF0007881224000066.tif44(u x ',u y '), symbol 42

[0199] TIFF0007881224000067.tif45=(u x '',u y ''), and symbol 43

[0200] TIFF0007881224000068.tif55=(u x ''',u y ''') specifies the coordinates of spot 221, which includes the first spot 221', the second spot 221'', and the third spot 221'''' formed by the light beam returned from the internal facet 214. The first spot 221' is the spot 221 closest to spot 231. d indicates the distance between the first spot 221' and spot 231 (i.e., symbol 44).

[0201] JPEG0007881224000069.jpg630 According to some embodiments, the angle of incidence of the incident light beam on the first surface 134a of the optical element (the angle at which the incident light beam is inclined with respect to the normal to the first surface 134a of the optical element) is given by symbol 45

[0202] JPEG0007881224000070.jpg724 Symbol 46

[0203] JPEG0007881224000071.jpg721 and symbol 47

[0204] It may be ensured that each of the JPEG0007881224000072.jpg720 images is much larger, thereby allowing for the identification of spot 231 (i.e., attributing spot 231 to the portion of the incident light beam that is directly reflected from the first surface 134a of the optical element).

[0205] According to some embodiments, the controller 108 may be communicatively associated with a computing module 146. The computing module 146 may include one or more processors, as well as volatile and / or non-volatile memory components. One or more processors may be configured to receive raw or processed sensed data (i.e., measurement data acquired by the photosensing component 124) from the controller 108 and to calculate the collective (e.g., mean or maximum) deviation from parallelism and / or the deviation from parallelism between pairs of internal facets 14. Raw sensed data may include the intensity of pixels constituting a spot formed by the reflected light beam focused on the photosensing component 124. Processed sensed data may include the center point (e.g., vector symbol 48) of the reflected light beam or the spot formed by the reflected light beam.

[0206] JPEG0007881224000073.jpg735 or vector symbol 49

[0207] (Coordinates of JPEG0007881224000074.jpg630) This may include the angular deviation between the (pair). According to some such embodiments, the calculation module 146 may be configured to process the raw sensed data of the light sensing component 124 to obtain the angular deviation between the returned light beams (pair) from the sensed data.

[0208] According to some embodiments, one or more processors may include graphics processing units (GPUs) configured to run image recognition software to identify spots 201 (or spots 221 and 231). According to some embodiments, for example, embodiments in which the first surface 134a of the optical element is not coated with a reflective coating, the image recognition software may be further configured to distinguish a spot formed by a light beam directly reflected from the first surface 134a of the optical element (e.g., spot 231) from a spot formed by a reflected light beam reflected from the internal facet 14 (e.g., spot 221).

[0209] According to some embodiments, the computing module 146 may be included in the system 100.

[0210] According to several alternative embodiments not depicted in the figures, the system 100 may include an interference setup instead of the optical setup 104, and information including radial deviations from parallelism between pairs of internal facets 14 may be extracted from the interference pattern formed by the returned light beam. According to some such embodiments, the interference setup may include an array of beam splitters and an associated array of controllably openable and closeable blocking filters configured to allow inspection of pairs of internal facets one at a time. More specifically, the beam splitter and blocking filter array may be configured to (i) split the incident beam into a selectable pair of incident subbeams incident normal to the optical element 102, and (ii) recombine the two returned subbeams, each induced by the pair of incident light beams, into a single combined returned light beam, which is then sensed by an image sensor. The beam splitter and blocking filter array are configured such that each selectable pair of incident subbeams induces reflection from each pair of internal facets using a first incident subbeam that probes one of the internal facets and a second incident subbeam that probes another internal facet. For example, the first incident subbeam induces reflection from the i-th internal facet (after it has been transmitted through the optical element 102 and passed through the optical element 102 and passed through the sample 10), and the second incident subbeam induces reflection from the j-th internal facet (after it has been transmitted through the optical element 102 and passed through the optical element 102 and passed through the sample 10), where i and j are controllably selectable. As will be readily apparent to those skilled in the art, the radial deviation from parallelism between the i-th and j-th internal facets can be extracted from the interference pattern formed on the optical sensor by the deviation.

[0211] According to some embodiments, each of the internal facets 14 can be inspected (probed) one at a time using, for example, a translationable slit optical mask, an aperture optical mask, or a shutter assembly. Figure 3 schematically illustrates an optics-based system 300 corresponding to a specific embodiment of system 100, configured to verify the parallelism between the internal facets of a sample by inspecting the internal facets one at a time. More specifically, Figure 3 shows cross-sectional side views of system 300 and sample 10 according to some embodiments. (It should be understood that sample 10 does not constitute part of system 300.)

[0212] System 300 includes a light-transmitting optical element 302, an optical setup 304, and optionally a controller 308, corresponding to specific embodiments of the optical element 102, the optical setup 104, and the controller 108, respectively. Optical element 302 includes a substrate 332, a first surface 334a of the optical element, and a second surface 334b ​​of the optical element, corresponding to specific embodiments of the substrate 132, the first surface 134a of the optical element, and the second surface 134b of the optical element, respectively.

[0213] The optical setup 304 includes an ICA 312 and an oriented retaining infrastructure 314, corresponding to specific embodiments of the ICA 112 and retaining infrastructure 114, respectively. The 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, the ICA 312 may further include an optical mask 356, which includes a slit 358. According to some embodiments, the optical mask 356 may be translatable to allow the slit 358 to be controllably positioned above any one of the internal facets 14, thereby allowing each of the internal facets 14 to be inspected one at a time. According to some such embodiments, the optical setup 304 may further include a motor 360, which may be mechanically associated with the optical mask 356 to allow the optical mask 356 to be translated. According to some embodiments, the motor 360 may be a linear stepping motor that can be mechanically coupled to the optical mask 356 via a screw 362.

[0214] Furthermore, a calculation module 346 corresponding to a specific embodiment of calculation module 146 is shown. According to some embodiments, calculation module 346 may be included in system 300.

[0215] According to several alternative embodiments not depicted in Figure 3, the ICA312 may include a shutter assembly comprising multiple individually openable and closable shutters instead of the optical mask 356 (and motor 360). Each shutter may be positioned above its respective internal facet, thereby allowing each of the internal facets 14 to be inspected one at a time.

[0216] During operation, according to some embodiments, the optical mask 356 is translated to successively position the slit 358 over each of the internal facets 14. For example, as depicted in Figure 3, when the slit 358 is positioned over the first internal facet 14a, a collimated light beam (not all numbered), indicated by arrow 305, is projected onto the optical mask 356 in a direction perpendicular to the first surface 334a of the optical element. The (first) incident portion of the collimated light beam passes through the slit 358, collides with the first surface 334a of the optical element in a direction normal to it, and is transmitted into the optical element 302, thereby obtaining a transmitted light beam. The first incident portion is indicated by arrow 355a, and the transmitted light beam is indicated by arrow 315a.

[0217] The transmitted light beam travels across the optical element 302, crosses the sample 10 via the second surface 334b ​​of the optical element and the first surface 16a of the sample, and propagates toward the first internal facet 14a. The transmitted light beam is reflected from the first internal facet 14a toward the second surface 16b of the sample. The first reflected light beam, corresponding to the portion of the transmitted light beam reflected at the first internal facet 14a, is indicated by arrow 325a. The first double-reflected light beam is obtained by the reflection of the first reflected light beam toward the first surface 16a of the sample from the second surface 16b of the sample. The first double-reflected light beam is indicated by arrow 335a. The first double-reflected (i.e., reflected twice: once at the first internal facet 14a and then at the second surface 16b of the sample) light beam exits the sample 10 and enters the optical element 302 via the first surface 16a of the sample and the second surface 334b ​​of the optical element. The first double-reflected light beam travels to the first surface 334a of the optical element, exits the optical element 302 (e.g., refracted), and thereby the first reflected light beam is obtained. The first reflected light beam is indicated by arrow 345a. After passing through the slit 358, the first reflected light beam travels to the autocollimator 352, which is sensed by the image sensor of the autocollimator 352.

[0218] The trajectories of the second incident portion, the second transmitted light beam, the second reflected light beam, the second double reflected light beam, and the second returned light beam are indicated by dotted arrows 355b, 315b, 325b, 335b, and 345b, respectively. These trajectories are realized when the optical mask 356 is translated so that the slit 358 is positioned on the second internal facet 14b. Arrows 355b, 315b, 325b, 335b, and 345b are represented by dotted lines indicating that these trajectories are not realized (i.e., if the slit 358 is positioned on the first internal facet 14a, there is no corresponding light beam) when the slit 358 is positioned on the first internal facet 14a. The trajectories of the third incident portion, the third transmitted light beam, the third reflected light beam, the third double-reflected light beam, and the third returned light beam are indicated by dotted arrows 355c, 315c, 325c, 335c, and 345c, respectively. These trajectories are realized when the optical mask 356 is translated so that the slit 358 is positioned on the third internal facet 14c. Arrows 355c, 315c, 325c, 335c, and 345c are represented by dotted lines indicating that these trajectories are not realized (i.e., if the slit 358 is positioned on the first internal facet 14a, there is no corresponding light beam) when the slit 358 is positioned on the first internal facet 14a.

[0219] According to some embodiments, the optical mask 356 can be continuously translated. As transmitted light is scanned along the internal facets, each spot formed on the image sensor of the autocollimator 352 remains essentially fixed (unless the internal facets are bent, curved, and / or otherwise deformed). As the transmitted light beam transitions over an adjacent internal facet, a new spot is formed on the image sensor (when the two internal facets are sufficiently offset). Once the transition is complete, only the new spot remains on the image sensor.

[0220] According to some alternative embodiments, the optical mask 356 can be shifted between different positions at multiple locations. At each of these locations, the slit 358 is positioned on one of the internal facets 14. The collimated light beam 305 can only be projected when the optical mask 356 is at one of the (different) locations.

[0221] To avoid obscuring Figure 3, the light beam reflected from the first surface 334a of the optical element is not shown.

[0222] Referring also to Figure 4, which schematically depicts the spot 401 on the digital display 464 of the autocollimator 352 according to several embodiments of the system 300, where the first surface 334a of the optical element is coated with an anti-reflective coating. The spot 401 includes, according to several embodiments, a first spot 401a, a second spot 401b, and a third spot 401c. Since the internal facets 14 are inspected one at a time, it is known which reflected light beam produced each of the spots 401, and therefore which internal facets 14 produced each of the spots 401. Thus, the deviation from parallelism between each pair of internal facets 14 can be calculated. The first spot 401a is formed by the first reflected light beam (indicated by arrow 345a in Figure 3). The second spot 401b is formed by the second reflected light beam (indicated by arrow 345b in Figure 3). The third spot 401c is formed by the third reflected light beam (indicated by arrow 345c in Figure 3).

[0223] Two-dimensional vector symbol 50

[0224] TIFF0007881224000075.tif44=(u 1,x ,u 1,y ), symbol 51

[0225] TIFF0007881224000076.tif45=(u 2,x,u 2,y ), and symbol 52

[0226] TIFF0007881224000077.tif44=(u 3,x ,u 3,y ) specifies the coordinates (e.g., center point) of the first spot 401a, the second spot 401b, and the third spot 401c, respectively. The pitch deviation between each pair of internal facets 14, as well as the roll deviation, are indicated by symbol 53

[0227] It can be calculated from the component values ​​of TIFF0007881224000078.tif633.

[0228] According to some embodiments in which a focusing lens with focal length f2 (not shown, e.g., focusing lens of an autocollimator) is used to focus the reflected light beam onto an image sensor (e.g., an image sensor of an autocollimator), the pitch δ of the second reflected light beam relative to the first reflected light beam is determined by selecting a suitable coordinate system. 21,p and roll δ 21,r The deviations are given by tan(δ) 21,p )=(u 2,x -u 1,x ) / f² and tan(δ 21,r )=(u 2,y -u 1,y ) / f² can be calculated via the same method. Similarly, the pitch δ of the third reflected light beam relative to the first reflected light beam. 31,p and roll δ 31,r The deviations are, respectively, tan(δ 31,p )=(u 3,x -u 1,x ) / f² and tan(δ 31,r )=(u 3,y -u 1,y The pitch δ of the third reflected light beam relative to the second reflected light beam can be calculated via ) / f2. 32,p and roll δ 32,r These are tan(δ 32,p )=(u 3,x -u 2,x ) / f² and tan(δ 32,r )=(u3,y -u 2,y ) / f2 can be calculated via this. Thus, the pitch ε for the first internal facet 14a 21,p and roll ε 21,r The deviation from the parallelism of the second internal facet 14b in is given by relation n, respectively. s ·sin(2ε 21,p ) = sin(δ 21,p ) and n s ·sin(2ε 21,r ) = sin(δ 21,r ) can be calculated using the pitch ε for the first internal facet 14a. 31,p and roll ε 31,r The deviations from the parallelism of the third internal facet 14c in are, respectively, n s ·sin(2ε 31,p ) = sin(δ 31,p ) and n s ·sin(2ε 31,r ) = sin(δ 31,r ) can be calculated using the pitch ε for the second internal facet 14b. 32,p and roll ε 32,r The deviations from the parallelism of the third internal facet 14c in are, respectively, n s ·sin(2ε 32,p ) = sin(δ 32,p ) and n s ·sin(2ε 32,r ) = sin(δ 32,r It can be calculated using ).

[0229] The magnitude of the deviation from parallelism (i.e., radial deviation) of the second internal facet 14b relative to the first internal facet 14a, the third internal facet 14c relative to the first internal facet 14a, and the third internal facet 14c relative to the second internal facet 14b is, respectively, related

number

number

number

[0230] According to some embodiments where the deviation from parallelism is sufficiently small, a small-angle approximation can be used. As will be apparent to those skilled in the art, under the 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) is the case.

[0231] According to some embodiments, the calculation module 346 may be configured to calculate the deviation from parallelism between some or all pairs of internal facets in the inspected sample. According to some embodiments, particularly those with a large number of internal facets, the calculation module 346 may be configured to calculate the deviation from parallelism between all pairs of adjacent internal facets in the inspected sample. According to some such embodiments, the calculation module 346 may be configured to calculate the deviation of one of the internal facets (e.g., the leading or trailing internal facet) from parallelism with respect to all the other facets. According to some embodiments, the calculation module 346 may be further configured to additionally calculate the uncertainty in the calculated deviation from parallelism.

[0232] Figure 5 schematically depicts a stage assembly 538 on which sample 10 is placed, according to several embodiments. An optical element 502 placed on sample 10 is also depicted. The stage assembly 538 and optical element 502 correspond to specific embodiments of the stage assembly 138 and optical element 102 of system 100. The second surface 534b of the optical element is inclined with respect to the first surface 534a of the optical element at an inclination angle σ'. The first surface 534a and the second surface 534b of the optical element correspond to specific embodiments of the first surface 134a and the second surface 134b of the optical element, respectively.

[0233] The stage assembly 538 includes a pitch goniometer 572, a roll goniometer 574, and an inclined platform 576. According to some embodiments, as depicted in Figure 5, the inclined platform 576 is mounted on the roll goniometer 574, and the roll goniometer 574 is mounted on the pitch goniometer 572. The inclined platform 576 includes an outer, flat platform top surface 578a and an outer, flat platform base surface 578b opposite the platform top surface 578a. According to some embodiments, the platform top surface 578a is inclined with respect to the base surface 578b at a platform inclination angle ι approximately equal to σ'.

[0234] The orientation of the inclined platform 576, and therefore the orientation of the sample 10 and the optical element 502, can be adjusted by aligning the pitch goniometer 572 and the roll goniometer 574, thereby making it possible to control the incident angle of the light beam projected onto the optical element 502, for example, by an ICA (not shown). According to some embodiments, each of the pitch goniometer 572 and the roll goniometer 574 may be oriented using a programmable micrometer (not shown). Additionally or alternatively, according to some embodiments, each of the pitch goniometer 572 and the roll goniometer 574 may be manually oriented.

[0235] Figures 6A and 6B schematically depict an optics-based system 600 for measuring internal facets within a sample, and according to some embodiments, Figure 6B is a magnified view of some parts of Figure 6A, indicated by the dashed line L'. The optics-based system 600 is configured to verify the parallelism between internal facets of a sample. More specifically, Figure 6A provides a cross-sectional side view of the system 600 and the sample 60 being inspected by the system 600, according to some embodiments. (It should be understood that the sample 60 does not constitute part of the system 600.)

[0236] Sample 60 includes a light-transmitting substrate 62 and two or more internal facets 64 embedded in the substrate 62. The substrate 62 has a refractive index n s The sample 60 may be characterized by '. The sample 60 further includes an outer first surface 66a (also referred to as the “first surface of the sample”) and an outer second surface 66b (also referred to as the “second surface of the sample”). The second surface of the sample 66b is opposite to the first surface of the sample 66a. Each of the first surface of the sample 66a and the second surface of the sample 66b may be flat. According to some embodiments, the second surface of the sample 66b may be parallel to the first surface of the sample 66a, as depicted in Figures 6A and 6B. According to some embodiments, each of the internal facets 64 constitutes a thin semi-reflective or reflective layer embedded in the substrate 62. According to some embodiments, the sample 60 may be a one-dimensional or two-dimensional reflective waveguide. According to some such embodiments, the first surface of the sample 66a and the second surface of the sample 66b constitute the main surfaces of the waveguide.

[0237] Sample 60 may be similar to Sample 10, but according to some embodiments, it may differ from Sample 10 in its internal dimensions (or at least ratios), particularly in the ratio of d1' / d2' to d1 / d2, as detailed below, and in its refractive index, where d1' is the distance between the first surface 66a and the second surface 66b of the sample, and d2' is the distance between adjacent internal facets (e.g., internal facets 64a and 64b, internal facets 64b and 64c). d1' and d2' are shown in Figure 6B.

[0238] Sample section 68 of sample 60 corresponds to a portion (e.g., a segment) of the substrate 62 on which the internal facets 64 are located (while a complementary section of sample 60 to sample section 68 may lack any of the internal facets 64). As a non-limiting example intended to facilitate the explanation by making it more specific, in Figures 6A and 6B, the internal facet 64 is shown to include three internal facets: a first internal facet 64a, a second internal facet 64b, and a third internal facet 64c, with the second internal facet 64b positioned between the first internal facet 64a and the third internal facet 64c. Those skilled in the art will readily recognize that a 3-internal facet case can contain any number of internal facets required (e.g., 4, 5, 10, or 11 or more).

[0239] The internal facets 64 are nominally parallel. In practice, due to imperfections in manufacturing, the internal facets 64 typically cannot exhibit perfect parallelism. According to some embodiments, each of the internal facets 64 has a nominal angle μ' approximately equal to 90° (extending on a plane parallel to the zx plane). nom The internal facet 64 is nominally inclined with respect to the first surface 66a of the sample. According to some such embodiments, as depicted in Figures 6A and 6B, the internal facet 64 is nominally perpendicular to the first surface 66a of the sample (and, in embodiments where the second surface 66b of the sample is parallel to the first surface 66a of the sample, the second surface 66b of the sample), i.e., μ' nom = 90°. In reality, each of the 64 internal facets is nominally angle μ' nom They can be oriented at their respective actual angles, which are slightly different from the first internal facet 64a, the second internal facet 64b, and the third internal facet 64c are oriented at a first angle μ'1, a second angle μ'2, and a third angle μ'3 with respect to the first surface 66a of the sample, respectively.

[0240] Due to imperfections in the manufacturing process, the actual angle μ' i(i=1, 2, 3) differ from each other not only in size but also in their respective angle-forming planes, and / or in their nominal angle μ', as described above for sample 10. nom Please note that this may differ from the actual situation.

[0241] Each of the first surface 66a and the second surface 66b of the sample extends from the first end 61a to the second end 61b of the sample 60. The sample section 68 defines a first region 63a and a second region 63b on the first surface 66a and the second surface 66b of the sample, respectively, with the internal facet 64 located between the first region 63a and the second region 63b.

[0242] According to some embodiments, system 600 includes a first optical element (FOE) 602, a second optical element (SOE) 682, and an optical setup 604. Each of the FOE 602 and SOE 682 is light-transmitting. System 600 may further include a controller 608 that is functionally associated with the optical setup 604 and configured to control the operation of the optical setup 604, as described in relation to the controller 108 and optical setup 104 of system 100. According to some embodiments, as depicted in Figure 6A, the optical setup 604 includes an illumination collection assembly (ICA) 612 and a retaining infrastructure 614 for mounting the sample 60 on the retaining infrastructure 614 itself. According to some embodiments, the retaining infrastructure 614 may include an orientation infrastructure configured to allow the orientation of the sample 60 to be set in a controllable manner. The ICA 612 includes a light source 622 (or more light sources) and a light-sensing component 624, which may be analogous to the light source 122 and light-sensing component 124 of system 100, respectively. According to some embodiments, the light-sensing component 624 may be a camera. According to some embodiments, the ICA 612 may further include an optical instrument 628 whose function may be similar to that of the optical instrument 128 of system 100.

[0243] FOE602 makes up the majority of FOE602 and has a refractive index (e.g., n) that is almost the same as that of substrate 62. s 'Greater than -0.02, n s The FOE 602 includes a substrate 632 made of a material having a refractive index less than +0.02. According to some such embodiments, the substrate 632 is made of a material having the same refractive index as the substrate 62. The FOE 602 further includes an outer first surface 634a and an outer second surface 634b opposite it. According to some embodiments, as depicted in Figure 6A, the first surface 634a of the FOE is flat. According to some such embodiments, as depicted in Figure 6A, the second surface 634b of the FOE is also flat and inclined with respect to the first surface 634a of the FOE. According to some embodiments, the FOE 602 is a prism. According to some such embodiments, the prism may be a triangular prism.

[0244] SOE682 makes up the majority of SOE682 and has a refractive index (for example, n) that is almost the same as that of substrate 62. s 'Greater than -0.02, n s The SOE 682 includes a substrate 692 made of a material having a refractive index less than +0.02. According to some such embodiments, the substrate 692 is made of a material having the same refractive index as the sample 60. The SOE 682 further includes an outer first surface 694a and an outer second surface 694b opposite it. According to some embodiments, as depicted in Figure 6A, the first surface 694a of the SOE is flat. According to some such embodiments, as depicted in Figure 6A, the second surface 694b of the SOE is also flat and inclined relative to the first surface 694a of the SOE. According to some embodiments, the SOE 682 is a prism. According to some such embodiments, the prism may be a triangular prism. According to some embodiments, the SOE 682 has the same dimensions as, or at least the same proportions as, the FOE 602.

[0245] According to some embodiments, the second surface 634b of the FOE and the second surface 694b of the SOE may be inclined with respect to the first surface 634a of the FOE and the first surface 694a of the SOE by a first inclination angle σ1 (formed parallel to zx) and a second inclination angle σ2 (formed parallel to zx), respectively. According to some embodiments, σ2 is approximately equal to σ1. σ1 and σ2 are shown in Figure 6B.

[0246] In some embodiments, particularly in embodiments where (i) the first surface 66a and the second surface 66b of the sample are parallel, (ii) the internal facets 64 are nominally perpendicular to each of the first surface 66a and the second surface 66b of the sample, and (iii) adjacent internal facets are spaced at regular intervals, each of σ1 and σ2 may be equal to (90° - arctan(d1' / d2')), i.e., 90 degrees minus arctan(d1 / d2). The reasons for selecting the inclination angle as described above are explained below.

[0247] ICA612 is configured to output a collimated light beam generated by light source 622 and optionally operated (e.g., collimated) by optical instrument 628 (in embodiments including optical instrument 628). According to some embodiments, optical instrument 628 may include a collimating lens or a collimating lens assembly (not shown). The relative orientation of FOE 602 and ICA612 (more precisely, the illumination component of ICA612) can be (controllably) set such that the light beam output by ICA612 collides with the first surface 634a of FOE in a direction normal to the surface, or at least substantially normal to the surface 634a of FOE (e.g., within 1°, 1.5°, or possibly 2° from the normal incidence).

[0248] According to some embodiments, the optical instrument 628 may further include a translationable slit-type or aperture-type optical mask (such as the translationable slit-type optical mask in Figure 7, not shown) configured to control the impact (i.e., strike) position of a light beam (e.g., a laser beam) on the first surface 634a of the FOE, thereby enabling separate inspection of each of the internal facets 64. Alternatively, according to some embodiments, the optical instrument 628 may further include a plurality of shutters configured to enable (allow) separate inspection of each of the internal facets 64.

[0249] According to some embodiments, the holding infrastructure 614 may be configured to mount or hold the sample 60 between the FOE 602 and SOE 682 such that each of the FOE 602 and SOE 682 is adjacent to the sample 60. More specifically, according to some such embodiments, the relative positioning of the sample 60 and the FOE 602 may be such that the second surface 634b of the FOE is adjacent to and optionally parallel to the first surface 66a of the sample, and the relative positioning of the sample 60 and the SOE 682 may be such that the second surface 694b of the SOE is adjacent to and optionally parallel to the second surface 66b of the sample.

[0250] According to some embodiments, the retaining infrastructure 614 may include a platform 638 having a slot (or hole) 696 extending into the platform 638 from the upper surface 698 of the platform 638. The slot 696 is configured to receive a sample 60 into the slot 696 such that a sample section 68 protrudes from the slot 696. The platform 638 is further configured to mount FOE 602 and SOE 682 on the platform 638, wherein the first surface 634a of the FOE is adjacent to and parallel to the first region 63a, and the second surface 694b of the SOE is adjacent to and parallel to the second region 63b.

[0251] According to some embodiments, the platform 638 may be operable in six degrees of freedom.

[0252] During operation, according to some embodiments, an enlarged and collimated incident light beam (not all numbered) indicated by arrow 605 is projected substantially normal to the first surface 634a of the FOE. According to some embodiments, the incident light beam can be projected normal to the first surface 634a of the FOE.

[0253] The incident light beam (or at least a portion thereof) is transmitted through (i.e., penetrates) the first surface 634a of the FOE to the FOE 602, thereby obtaining a transmitted light beam. The transmitted light beam is indicated by arrows 615 (not all of which are numbered). The transmitted light beam travels across the FOE 602, crosses the sample 60 through the second surface 634b of the FOE and the first surface 66a of the sample (i.e., is transmitted into the sample 60), and propagates toward the internal facet 64. The transmitted light beam is reflected from the internal facet 64 toward the second surface 66b of the sample.

[0254] More specifically, since the internal facets 64 may differ slightly from each other in their respective orientations, the transmitted light beam may be reflected from each of the internal facets 64 at slightly different angles. Thus, multiple reflected light beams with slightly different propagation directions may be obtained. The first reflected light beam, corresponding to the portion of the transmitted light beam reflected from the first internal facet 64a, is indicated by arrow 625a. The second reflected light beam, corresponding to the portion of the transmitted light beam reflected from the second internal facet 64b, is indicated by arrow 625b. The third reflected light beam, corresponding to the portion of the transmitted light beam reflected from the third internal facet 64c, is indicated by arrow 625c.

[0255] The reflected light beam exits sample 60 via the second surface 66b of the sample and enters SOE682 via the second surface 694b of the SOE. The reflected light beam then travels to the first surface 694a of the SOE and exits SOE682 (e.g., is refracted), thereby acquiring a second set of light beams (also referred to as "exit beams"). The first exit beam, resulting from the refraction of the first reflected light beam from SOE682, is indicated by arrow 635a. The second exit beam, resulting from the refraction of the second reflected light beam from SOE682, is indicated by arrow 635b. The third exit beam, resulting from the refraction of the third reflected light beam from SOE682, is indicated by arrow 635c. The emitted light beam propagates toward the ICA612, is focused onto the light-sensing component 624 by the optical instrument 628, and is sensed by the light-sensing component 624 (for example, by an image sensor included in the light-sensing component 624).

[0256] According to some embodiments, each of σ1 and σ2 is equal to (90° - arctan(d1' / d2')). As is evident by examining Figures 6A and 6B, selecting σ1 and σ2 as described above ensures that substantially all rays in the reflected light beam (or at least a portion thereof) exit the sample 60 through the second surface 66b of the sample and are transmitted into the SOE 682 without being reflected again by either the internal facet 14 or the first surface 66a of the sample. Thus, selecting σ1 and σ2 as described above reduces losses and thereby improves the detection of the reflected light beam (for example, by ensuring that the reflected light beam forms a bright spot on the photosensitive surface of the image sensor). According to some embodiments, each of σ1 and σ2 may be equal to approximately (90° - arctan(d1' / d2')).

[0257] According to some embodiments, the first surface 634a of the FOE and the first surface 694a of the SOE may be coated with an anti-reflective coating to increase the intensity of light transmitted into the FOE 602 and light refracted from the SOE 682, respectively.

[0258] To avoid obscuring the viewability of Figures 6A and 6B, the light beam reflected from the first surface 634a of the FOE is not shown.

[0259] According to some embodiments, the controller 608 may be communicatively associated with a computing module 646. The computing module 646 may include one or more processors, as well as volatile and / or non-volatile memory components. One or more processors may be configured to receive raw or processed sensed data acquired by the photosensing component 624 from the controller 608 and, based thereon, calculate the parallelism and / or collective (e.g., mean and / or maximum) deviations between pairs of internal facets 64, as essentially detailed above in the description of system 100. Raw sensed data may include the intensities of pixels constituting a spot formed by an outgoing light beam focused on the photosensing component 624. Processed sensed data may include the angular deviation between pairs of center points of the outgoing light beam or the spot formed by the outgoing light beam. According to some such embodiments, the computing module 646 may be configured to process the raw sensed data acquired by the photosensing component 624 and to obtain the angular deviation between pairs of outgoing light beams from the raw sensed data.

[0260] According to some embodiments, one or more processors may include graphics processing units (GPUs) configured to run image recognition software to identify spots formed by an emitted light beam on an image sensor included in the light-sensing component 624. According to some embodiments, a computing module 646 may be included in the system 600.

[0261] From the angular deviation between the emitted light beams, the magnitude of the deviation from the parallelism between the internal facets can be inferred, as essentially detailed above in the description of System 100. The angular deviation can be derived from sensed data of the emitted light beams obtained using the photosensing component 624 (e.g., from the coordinates of the spot formed by the emitted light beams on the image sensor of the photosensing component 624), as essentially detailed above in the description of System 100. According to some embodiments, the derivation of the angular deviation may involve the use of image recognition software, and optionally other software (both of which may be performed by the calculation module 146), for identifying the spot formed by the emitted light beams on the image sensor, calculating the coordinates of the spot (e.g., its center point), etc., as essentially detailed above in the description of System 100.

[0262] As a non-limiting example, according to some embodiments that use a collimating lens with focal length f1' to focus the outgoing light beam onto an image sensor (e.g., an autocollimator), the maximum radial deviation ε' from the parallelism between the internal facets 64 (or pairs thereof) is max is related

number

[0263] TIFF0007881224000083.tif56=(u' α,x ,u' α,y ), symbol 55

[0264] TIFF0007881224000084.tif56=(u' β,x ,u' β,y ), and symbol 56

[0265] TIFF0007881224000085.tif56=(u' γ,x ,u' γ,y These are two-dimensional vectors that specify the coordinates of the first spot, the second spot, and the third spot, respectively, formed on the image sensor by the emitted light beam.

[0266] According to some embodiments, the parallelism ε' between internal facets 64 avg The mean radial deviation from is related to

number

number

number

[0267] JPEG0007881224000089.jpg546 Symbol 58, as detailed above.

[0268] This can be inferred from JPEG0007881224000090.jpg633.

[0269] According to some embodiments where the deviation from parallelism is sufficiently small, small-angle approximation can be used. Under small-angle approximation (when calculated in radians),

number

number

number

[0270] According to some embodiments, the second surface 634b of the FOE does not contact the first surface 66a of the sample, and the second surface 694b of the SOE does not contact the second surface 66b of the sample. According to some such embodiments, as essentially described above in the description of system 100, refractive index matching shape-fitting interfaces (not shown) may be inserted between the FOE 602 and the sample 60, and between the SOE 682 and the sample 60. The shape-fitting interfaces are substantially the same as the substrate 62 (e.g., n s 'Greater than -0.02, n s It may have a refractive index less than +0.02.

[0271] According to several alternative embodiments not depicted in the figures, the system 600 may include an interference setup instead of the optical setup 604, and information including radial deviations from parallelism between pairs of internal facets 64 may be extracted from the interference pattern formed by the exit light beam. According to some such embodiments, the interference setup may include an array of beam splitters and an associated array of controllably openable and closeable blocking filters configured to allow inspection of pairs of internal facets one at a time. More specifically, the beam splitter and block filter array may be configured to (i) split the incident beam into a selectable pair of incident subbeams incident normal to the FOE 602, and (ii) recombine the two exit subbeams (i.e., each subbeam leaving the SOE 682) induced by the pair of incident light beams into a single combined exit light beam, which is then sensed by the component. The beam splitter and blocking filter array are configured such that each selectable pair of incident subbeams induces reflection from each pair of internal facets, with the first incident subbeam probing one of the internal facets and the second incident subbeam probing the other internal facet. For example, the first incident subbeam induces reflection from the i-th internal facet (after it has been transmitted into FOE 602, passed through FOE 602, and transmitted into sample 60), and the second incident subbeam induces reflection from the j-th internal facet (after it has been transmitted into FOE 602, passed through FOE 602, and transmitted into sample 60), where i and j are controllably selectable. As will be readily apparent to those skilled in the art, the radial deviation from parallelism between the i-th and j-th internal facets can be extracted from the interference pattern formed on the photosensor by the deviation.

[0272] According to several embodiments, each of the internal facets 64 can be inspected (probed) one at a time using, for example, a translationable slit optical mask, an aperture optical mask, or a shutter assembly. Figure 7 schematically illustrates an optics-based system 700 corresponding to a specific embodiment of system 600, configured to verify the parallelism between the internal facets of a sample by inspecting the internal facets one at a time. More specifically, Figure 7 presents cross-sectional side views of system 700 and sample 60 according to several embodiments. (It should be understood that sample 60 does not constitute part of system 700.)

[0273] System 700 includes a light-transmitting FOE 702, a light-transmitting SOE 782, an optical setup 704, and optionally a controller 708, each corresponding to a specific embodiment of the FOE 602, SOE 682, optical setup 604, and controller 608, respectively. FOE 702 includes a first surface 734a and a second surface 734b of the FOE, each corresponding to a specific embodiment of the first surface 634a and second surface 634b of the FOE, respectively. SOE 782 includes a first surface 794a and a second surface 794b of the SOE, each corresponding to a specific embodiment of the first surface 694a and second surface 694b of the SOE, respectively.

[0274] The optical setup 704 includes an ICA 712 and a retaining infrastructure 714, corresponding to specific embodiments of the ICA 612 and the retaining infrastructure 614, respectively. The ICA 712 includes a light source 722, an image sensor 724, a collimating lens 740, and a focusing lens 750. According to some embodiments, the ICA 712 may further include an optical mask 756 including a slit 758. According to some embodiments, the optical mask 756 may be translatable to allow the slit 758 to be controllably positioned above any one of the internal facets 64, thereby allowing each of the internal facets 64 to be inspected one at a time. According to some such embodiments, the optical setup 704 may further include a motor 760, which may be mechanically associated with the optical mask 756 to allow the optical mask 756 to be translated. According to some embodiments, the motor 760 may be a linear stepping motor that can be mechanically coupled to the optical mask 756 via a screw 762.

[0275] A platform 738 that houses infrastructure 714 is also shown. Platform 738 corresponds to a specific embodiment of platform 638 that houses infrastructure 614.

[0276] Furthermore, a calculation module 746 corresponding to a specific embodiment of calculation module 646 is shown. According to some embodiments, calculation module 746 may be included in system 700.

[0277] According to several alternative embodiments not depicted in Figure 7, the ICA712 may include a shutter assembly comprising multiple individually openable and closable shutters instead of the optical mask 756 (and motor 760). Each shutter may be positioned above its respective internal facet, thereby allowing each of the internal facets 64 to be inspected one at a time.

[0278] During operation, according to some embodiments, the optical mask 756 is translated to successively position the slit 758 over each of the internal facets 64. For example, as depicted in Figure 7, when the slit 758 is positioned over the first internal facet 64a, a collimated light beam (not all numbered) indicated by arrow 705 is projected onto the optical mask 756 in a direction perpendicular to the first surface 734a of the FOE. (More specifically, light generated by the light source 722 may be collimated by the collimating lens 740, thereby preparing a collimated light beam.) The (third) incident portion of the collimated light beam passes through the slit 758, collides with the first surface 734a of the FOE in a direction normal to it, penetrates the first surface 734a of the FOE and is transmitted into the FOE 702, thereby obtaining a (third) transmitted light beam. The incident portion is indicated by arrow 745c, and the transmitted light beam is indicated by arrow 715c.

[0279] The transmitted light beam travels across FOE 702, crosses the sample 60 via the second surface 734b of the FOE and the first surface 66a of the sample (i.e., is transmitted into the sample 60), and propagates toward the third internal facet 64c. The transmitted light beam is reflected from the third internal facet 64c toward the second surface 66b of the sample, thereby acquiring the (third) reflected light beam. The reflected light beam is indicated by arrow 725c. The reflected light beam exits the sample 60 via the second surface 66b of the sample and the second surface 794b of the SOE and enters SOE 782. The light beam travels toward the first surface 794a of the SOE and exits SOE 782 (e.g., is refracted), thereby acquiring the third emitted light beam. The emitted light beam is indicated by arrow 735c. The emitted light beam passes through the slit 758, is focused by the focusing lens 750 on the image sensor 724, and is then detected.

[0280] The trajectories of the first incident portion, the first transmitted light beam, the first reflected light beam, and the first exit (e.g., refracted) light beam are indicated by dotted arrows 745a, 715a, 725a, and 735a, respectively. These trajectories are realized when the optical mask 756 is translated so that the slit 758 is positioned on the first internal facet 64a. Arrows 745a, 715a, 725a, and 735a are represented by dotted lines to indicate that these trajectories are not realized when the slit 758 is positioned on the third internal facet 64c (i.e., when the slit 758 is positioned on the third internal facet 64c, there is no corresponding light beam). The trajectories of the second incident portion, the second transmitted light beam, the second reflected light beam, and the second exit (e.g., refracted) light beam are indicated by dotted arrows 745b, 715b, 725b, and 735b, respectively. These trajectories are realized when the optical mask 756 is translated so that the slit 758 is positioned on the second internal facet 64b. Arrows 745b, 715b, 725b, and 735b are represented by dotted lines to indicate that these trajectories are not realized when the slit 758 is positioned on the third internal facet 64c (i.e., when the slit 758 is positioned on the third internal facet 64c, there is no corresponding light beam).

[0281] To avoid obscuring Figure 7, the light beam reflected from the first surface 734a of the FOE is not shown.

[0282] According to some embodiments, the optical mask 756 can be continuously translated, as essentially described above with respect to the optical mask 356 of system 300. According to some alternative embodiments, the optical mask 756 can be shifted between different positions of a plurality of positions, as essentially described above with respect to the optical mask 356 of system 300.

[0283] As essentially detailed above in the description of System 300, the deviation from the parallelism between two internal facets on which the two light beams can be traced can be inferred from the angular deviation between the two emitted light beams. The angular deviation can be calculated from the sensed data of the two emitted light beams (for example, from the center point of the spot formed on the image sensor 724 by the two emitted light beams). This is illustrated below as a non-limiting example, and according to some embodiments, the emitted light beams are focused onto the component 724 using a focusing lens 750 with a focal length f2'.

[0284] Two-dimensional vector symbol 59

[0285] TIFF0007881224000094.tif55=(u1' ,x ,u1' ,y ), symbol 60

[0286] TIFF0007881224000095.tif56=(u2' ,x ,u2' ,y ), and symbol 61

[0287] TIFF0007881224000096.tif55=(u3' ,x ,u3' ,y ) specifies the coordinates (e.g., center point) of the first spot, the second spot, and the third spot, respectively. The first spot is induced by light reflected from the first internal facet 64a, the second spot is induced by light reflected from the second internal facet 64b, and the third spot is induced by light reflected from the third internal facet 64c. By suitably selecting the coordinate system, the pitch δ' of the second reflected light beam relative to the first reflected light beam is determined. 21,p and roll δ' 21,r The deviations are, respectively, tan(δ' 21,p )=(u2' ,x -u1' ,x ) / f2' and tan(δ' 21,r )=(u2' ,y -u1' ,y) / f2' can be calculated via the same method. Similarly, the pitch δ' of the third reflected light beam relative to the first reflected light beam. 31,p and roll δ' 31,r The deviations are, respectively, tan(δ' 31,p )=(u3' ,x -u1' ,x ) / f2' and tan(δ' 31,r )=(u3' ,y -u1' ,y The pitch δ' of the third returned beam relative to the second returned light beam can be calculated via ) / f2'. 32,p and roll δ' 32,r The deviations are, respectively, tan(δ' 32,p )=(u3' ,x -u2' ,x ) / f2' and tan(δ' 32,r )=(u3' ,y -u2' ,y It can be calculated via ) / f2'. Therefore, the pitch ε' of the second internal facet 64b relative to the first internal facet 64a. 21,x and roll ε' 21,y The deviations from parallelism are, respectively, related to n. s '·sin(2ε)' 21,p )=sin(δ' 21,p ) and n s '·sin(2ε)' 21,r )=sin(δ' 21,r The pitch ε' of the third internal facet 64c relative to the first internal facet 64a can be calculated using ). 31,p and roll ε' 31,r The deviations from parallelism are, respectively, n s '·sin(2ε)' 31,p )=sin(δ' 31,p ) and n s '·sin(2ε)' 31,r )=sin(δ' 31,r The pitch ε' of the third internal facet 64c relative to the second internal facet 64b can be calculated using ). 32,p and roll ε' 32,r The deviations from parallelism are, respectively, n s '·sin(2ε)' 32,p)=sin(δ' 32,p ) and n s '·sin(2ε)' 32,r )=sin(δ' 32,r It can be calculated using ).

[0288] According to some embodiments where the deviation from parallelism is sufficiently small, a small-angle approximation can be used. As will be apparent to those skilled in the art, under the small-angle approximation (when calculated in radians), ε' 21,p =(u2' ,x -u1' ,x ) / (2n s '·f2') and ε' 21,r =(u2' ,y -u1' ,y ) / (2n s '·f2'), ε' 31,p =(u3' ,x -u1' ,x ) / (2n s 'f2') and ε' 31,r =(u3' ,y -u1' ,y ) / (2n s '·f2'), and ε' 32,p =(u3' ,x -u2' ,x ) / (2n s 'f2') and ε' 32,r =(u3' ,y -u2' ,y ) / (2n s It is 'f2').

[0289] method According to some embodiments, an optical-based method for measuring the internal facets of a sample is provided. The method may be used to verify the parallelism between the internal facets of a sample. Figure 8 shows a flowchart of such a method, i.e., an optical-based method 800, according to some embodiments. Method 800 may include the following steps: -Step 810 provides the sample to be tested (e.g., sample 10 or 60). The sample has a refractive index n sThe apparatus includes a light-transmitting substrate (e.g., substrate 12 or 62) and two or more nominally parallel internal facets (e.g., internal facets 14 or 64) embedded in the substrate. Each internal facet is oriented perpendicular to the outer, flat first surface of the sample. -n s (For example, n s Greater than -0.02, n s Step 820 provides a (first) optical element (e.g., optical element 102 or 302, or FOE 602 or 702, or similar) having a refractive index approximately equal to (less than +0.02). The optical element includes an outer, flat first surface and an outer, flat second surface facing the first surface of the optical element and inclined with respect to the first surface at an acute (first) inclination angle. - Step 830, in which the sample and optical element are positioned such that the second surface of the optical element is adjacent to the first surface of the sample. - Step 840, in which a first set of light beams (also called "incident light beams") are projected onto a first surface of an optical element in a direction approximately normal to the first surface (for example, within 2° of the normal incidence). -Step 850 in which each of the first set of light beams passes through an optical element, is transmitted into the sample, is reflected from an internal facet, and exits the sample (i.e., is transmitted through the sample), resulting in the acquisition of a second set of light beams. -A second set of light beams is detected (for example, measured using the light sensing component 124) in step 860. -Step 870 in which, based on the sensed data (obtained in step 860), at least one deviation from the parallelism between at least some of the internal facets is calculated.

[0290] As used herein, the term “acquisition” can be used in both active and passive senses. For example, in step 850, the second plurality of light beams may be acquired not as a result of any action performed in step 850, but rather as a consequence of the generation of the first plurality of light beams in step 840. Generally, a step may represent an active action performed by the user or by the system used to implement the method, and / or the result or effect of one or more actions performed in one or more preceding steps.

[0291] Method 800 may be used to verify the parallelism between internal facets of a sample, such as sample 10 or sample 60. In particular, Method 800 may be used to verify the parallelism between internal facets of a one-dimensional waveguide, as well as between internal facets of a two-dimensional waveguide.

[0292] Method 800 can be carried out using an optical-based system, such as one of Systems 100, 300, 600, and 700, or a similar system, as detailed above in the respective descriptions of Systems 100, 300, 600, and 700.

[0293] In some embodiments, a single optical element, such as optical element 102 or optical element 302, is employed. In some embodiments, the second plurality of light beams are obtained after the light beams (first) pass through the optical element, are reflected once from the internal facets, and then pass through the optical element again, as described above in the descriptions of Figures 1A-1E and Figure 3, and later in the description of Figure 9. In some embodiments, the optical element may be a prism (e.g., a triangular prism).

[0294] In some embodiments, a pair of optical elements, namely a first optical element (e.g., FOE602 or 702) and a second optical element (e.g., SOE682 or 782), may be used. In some embodiments, the second set of light beams are acquired after passing through the first optical element (once), through the sample, being reflected once from the internal facets, and passing through the second optical element (once), as described above in the descriptions of Figures 6A and 6B and Figure 7, and later in the description of Figure 10. In some embodiments, each of the optical elements may be a prism (e.g., a triangular prism).

[0295] According to some embodiments, in step 840, the first plurality of light beams constitute complementary portions of the collimated magnified light beam. According to some embodiments, the magnified light beam may be monochromatic. According to some such embodiments, the magnified light beam may be a laser beam.

[0296] According to some embodiments, the internal facets are inspected sequentially one after another. According to some such embodiments, the internal facets can be inspected "continuously" by scanning the light points on the internal facets one internal facet at a time.

[0297] According to some embodiments, the internal facets are examined (probed) one at a time. More specifically, according to some embodiments, steps 840, 850, and 860 may be performed N times, where N is the number of internal facets, and in each implementation, the light is made to strike only one of the internal facets, essentially as described above in the description of System 100 by some embodiments of System 100, the description of System 300, or the description of System 600 by some embodiments of System 600, and the description of System 700.

[0298] According to some embodiments, the image sensor is used to sense a second plurality of light beams (for example, when a camera and / or autocollimator is used), and step 870 may include an initial substage in which image recognition software is used to identify spots formed on the photosensitive surface of the image sensor by the second plurality of light beams (for example, spot 201, spot 401, a spot formed on the image sensor of system 600, or a spot formed on image sensor 724). According to some embodiments, the initial substage may further include assigning coordinates to each of the spots, for example, determining the center point of the spot. According to some embodiments, the center point may be determined by averaging the coordinates of each point constituting the spot, weighted by the intensity of the points.

[0299] According to some embodiments in which internal facets are inspected one at a time, in step 870, the deviation from parallelism between adjacent pairs of internal facets is calculated. Additionally or alternatively, according to some embodiments, the deviation from parallelism between each internal facet (excluding the reference internal facet) and the reference internal facet (e.g., the outermost facet) is calculated. According to some embodiments, the deviation from parallelism between each pair of internal facets is calculated. According to some embodiments, based on the calculated deviations, one or more of the average deviation and / or maximum deviation from parallelism is calculated. According to some embodiments, the average deviation and / or maximum deviation in pitch and / or roll can be calculated. The description of Figures 9 and 10 details below how various deviations from parallelism (as described above) can be calculated.

[0300] According to several embodiments, an optical-based method for measuring the internal facets of a sample is provided. The method may be used to verify the parallelism between the internal facets of a sample. Figure 9 shows a flowchart of such a method, i.e., an optical-based method 900, according to several embodiments. Method 900 may include the following steps: -Step 910 provides the sample to be tested (e.g., sample 10). The sample has a refractive index n s The apparatus includes a light-transmitting substrate having ' and two or more nominally parallel internal facets (e.g., internal facet 14) embedded in the substrate. Each internal facet is oriented perpendicular to a first flat surface outside the sample and a second flat surface outside the sample. -n s ' is approximately equal to (for example, n s 'Greater than -0.02, n s Step 920 provides an optical element (e.g., optical element 102 or optical element 302) having a refractive index less than +0.02. The optical element includes an outer, flat first surface and an outer, flat second surface that is opposite to the first surface of the optical element and is inclined at an acute angle with respect to the first surface. -Step 930 in which the sample and optical element are positioned such that the second surface of the optical element is adjacent to the first surface of the sample. - Step 940, in which a first set of light beams (also called "incident light beams") are projected onto a first surface of an optical element in a direction approximately normal to the first surface (for example, within 2° of the normal incidence). -Step 950, in which a second set of light beams (also referred to as "returned light beams") are obtained as a result of each of the incident light beams passing through an optical element, transmitting into the sample, being reflected from the internal facets and second surface of the sample, and passing through the optical element again. -Step 960 in which a second set of light beams are sensed (i.e., measured using, for example, the light sensing component 124). -Step 970 in which, based on the sensed data (obtained in step 960), at least one deviation from the parallelism between at least some of the internal facets is calculated.

[0301] Method 900 corresponds to a specific embodiment of Method 800. Method 900 can be used to verify the parallelism between internal facets of a sample, such as Sample 10. Method 900 can be carried out using an optical-based system, such as one of Systems 100 and 300, or a similar system, as taught above in the description of Figures 1A-5.

[0302] According to some embodiments, an autocollimator (e.g., autocollimator 352) is used to carry out steps 940, 950, and 960, for example, as detailed above in the description of System 100 and System 300 by some embodiments of System 100. According to some embodiments, the autocollimator includes an image sensor, and in step 960, a second plurality of light beams are sensed by the image sensor. Alternatively, according to some embodiments, the autocollimator is a visual autocollimator, and the returned light beam is sensed using the eyepiece assembly of the autocollimator (by viewing a graduated reticle through the eyepiece).

[0303] (i) an image sensor is used to sense the reflected light beam; (ii) step 970 includes an initial substage in which image recognition software is used to identify a spot formed on the photosensitive surface of the image sensor by the reflected light beam; and (iii) according to some embodiments in which the first surface of the optical element is not coated with a reflective coating, and as a result an additional spot (e.g., spot 211) is formed on the photosensitive surface of the image sensor (i.e., by light directly reflected from the first surface of the optical element), the image recognition software may be further configured to distinguish the additional spot from the spot formed by the reflected light beam.

[0304] According to some embodiments, each of the returned light beams can be traced back to each specific internal facet (for example, by inspecting the internal facets one at a time), and the pitch ε between the i-th internal facet and the j-th internal facet is such that ij,p The deviation is related to tan(δ ij,p )=(x i -x j ) / f1 and n s ·sin(2ε ij,p ) = sin(δ ij,p ) can be calculated using ε. Similarly, the roll ε between the i-th internal facet and the j-th internal facet ij,y The deviation is related to tan(δ ij,r )=(y i -y j ) / f1 and n s ·sin(2ε ij,r ) = sin(δ ij,r ) can be calculated using, where f1 is the focal length of the focusing lens or focusing lens assembly used to focus the reflected light beam onto the photosensing component used to sense the reflected light beam. i and x j These are the determined x-coordinates of the i-th and j-th reflected light beams, respectively (for example, the horizontal coordinates of the center point of the spot formed on the image sensor by those reflected light beams). i and y j These are the determined y-coordinates of the i-th and j-th reflected light beams, respectively (for example, the vertical coordinates of the center point of the spot formed on the component by those reflected light beams). (By suitably selecting the coordinate system, the pitch tilt and the roll tilt are separated, so that the pitch affects only the x-coordinate value of the spot, and the roll affects only the y-coordinate value of the spot.)

[0305] Parallelism ε of the i-th internal facet to the j-th internal facet ij The radial deviation from is related to

number

[0306] According to some embodiments where the deviation from parallelism is sufficiently small, a small-angle approximation can be used. As will be apparent to those skilled in the art, under the small-angle approximation (when calculated in radians), ε ij,p =(x i -x j ) / (2n s f1) and ε ij,r =( y i -y j ) / (2n s f1) is the case.

[0307] According to some embodiments, determining the coordinates of a spot may involve calculating the associated uncertainty and, based thereon, calculating the uncertainty in the deviation from parallelism between pairs of internal facets.

[0308] According to some embodiments, in step 970, the mean radial deviation from parallelism (i.e., the mean magnitude of the deviation) and / or the maximum radial deviation from parallelism (i.e., the magnitude of the deviation) are calculated, in which case the internal facets are not examined one by one at a time (e.g., all internal facets are examined simultaneously), and thereby the determined coordinates of the reflected light beam (e.g., the center point of the spot formed on the image sensor by the reflected light beam) typically do not belong to one of the internal facets (at least not without additional data). According to some embodiments, the angular deviation between pairs of reflected light beams may be calculated first. More specifically, the mean radial deviation from parallelism is related

number

number

number

[0309] According to some embodiments, the first surface of the optical element may be coated with an anti-reflective coating to eliminate the need to distinguish between the returned light beam and the light directly reflected from the first surface of the optical element. Additionally or alternatively, according to some embodiments, the incident light beam may be slightly inclined by an angle Δ' with respect to the normal to the first surface of the optical element. |Δ'| is selected to be large enough to reliably distinguish the returned light beam from the light directly reflected from the first surface of the optical element, as described above in the description of system 100. According to some embodiments, this is 0.3°≦|Δ'|≦0.5°, 0.2°≦|Δ'|≦0.7°, or possibly 0.1°≦|Δ'|≦1°. Each possibility corresponds to a different embodiment.

[0310] According to some embodiments, particularly embodiments in which the first surface of the sample and / or the first surface of the optical element are not sufficiently polished and / or cannot be aligned with sufficient precision, in order to eliminate or at least mitigate dispersion, the refractive index of the (sample) substrate is made approximately the same as that of the (sample) substrate (e.g., n) as detailed above in the description of System 100. s 'Greater than -0.02, n sA shape-matching interface having a value less than +0.02 may be placed between the optical element and the sample.

[0311] According to several embodiments, an optical-based method for measuring the internal facets of a sample is provided. The method may be used to verify the parallelism between the internal facets of a sample. Figure 10 shows a flowchart of such a method, i.e., an optical-based method 1000, according to several embodiments. Method 1000 may include the following steps: -Step 1010 provides the sample to be tested (e.g., sample 60). The sample has a refractive index n s The apparatus includes a light-transmitting substrate having `"` and two or more nominally parallel internal facets (e.g., internal facet 64) embedded in the substrate. Each internal facet is oriented perpendicular to a first flat surface outside the sample and a second flat surface outside the sample. -Step 1020 provides a first optical element (FOE, e.g., FOE602 or FOE702) and a second optical element (SOE, e.g., SOE682 or SOE782). Each of the FOE and SOE is n s Approximately equal to '' (for example, n s Greater than -0.02, n s Each surface has a refractive index less than ''+0.02. The FOE includes an outer, flat first surface and an outer, flat second surface that is opposite the first surface of the FOE and is inclined with respect to the first surface at an acute angle. The SOE includes an outer, flat first surface and an outer, flat second surface that is opposite the first surface of the SOE and is inclined with respect to it at approximately an angle of inclination (of the second surface of the FOE with respect to the first surface of the FOE). -Step 1030 in which the sample is placed between the FOE and SOE, and the sample, FOE, and SOE are positioned such that the second surface of the FOE and the second surface of the SOE are adjacent to the first surface of the sample and the second surface of the sample, respectively. -Step 1040 in which multiple incident light beams are projected onto the first surface of the FOE in a direction approximately normal to the beam (for example, within 1°, 1.5°, or 2° from the normal incidence). -Step 1050 in which a second set of light beams (also called "exit beams") are acquired by the incident light beam passing through the FOE, through the sample, being reflected once from the internal facets, through the SOE, and exiting the SOE (for example, being refracted). -Step 1060 in which a second set of light beams are detected (i.e., measured, for example, by using a light-sensing component 624 or an image sensor 724). -Step 1070 calculates at least one deviation from the parallelism between at least some of the internal facets based on the sensed data.

[0312] Method 1000 corresponds to a specific embodiment of Method 800. Method 1000 can be used to verify the parallelism between internal facets of a sample, such as Sample 60. Method 1000 can be carried out using an optical-based system, such as one of Systems 600 and 700, or a similar system, as taught above in the description of Figures 6A-7.

[0313] According to some embodiments, each of the light beams emanating from the SOE can be traced back to a specific internal facet in the sample (for example, by inspecting the internal facets one at a time), and the pitch between the i-th internal facet and the j-th internal facet is ε''. ij,p The deviation is related to tan(δ'' ij,p )=(x' i -x' j ) / f2 and n s ''·sin(2ε'' ij,p )=sin(δ'' ij,p ) can be calculated using the roll ε''. Similarly, roll ε'' ij,r The deviation between the i-th and j-th internal facets is given by the relation tan(δ''). ij,r )=(y' i -y' j) / f1 and n s ''·sin(2ε'' ij,r )=sin(δ'' ij,r This can be calculated using ). f2 is the focal length of the focusing lens or focusing lens assembly used to focus the outgoing light beam, which is used to sense the outgoing light beam. x' i and x' j y' is the determined x-coordinate of the i-th and j-th emitted light beams, respectively (for example, the horizontal coordinate of the spot formed on the image sensor by the emitted light beams). i and y' j These are the determined y-coordinates of the i-th and j-th emitted light beams, respectively (for example, the vertical coordinates of the spot formed on the image sensor by the emitted light beams). (Here, as described above in the description of Method 900, it is implicitly assumed that the coordinate system is one in which the pitch inclination and the roll inclination are separated.)

[0314] According to some embodiments, determining the coordinates of a spot may involve calculating the associated uncertainty and, based thereon, calculating the uncertainty in the deviation from parallelism between pairs of internal facets.

[0315] According to some embodiments, in step 1070, the mean radial deviation from parallelism and / or the maximum radial deviation from parallelism are calculated, in which the internal facets are not inspected one by one at a time, and thereby the determined coordinates of the emitted light beam (e.g., the center point of the spot formed on the image sensor by the emitted light beam) cannot typically be attributed to one of the internal facets. According to some embodiments, first, the angular deviation between pairs of emitted light beams can be calculated. More specifically, the mean radial deviation from parallelism is related

number

number

number

[0316] According to some embodiments, in particular, according to embodiments in which the first and second surfaces of the sample and / or the second surface of the FOE and the second surface of the SOE are not sufficiently polished and / or cannot be aligned with sufficient precision, in order to eliminate or at least mitigate dispersion, the substrate (of the sample) is made substantially the same as (e.g., n) as detailed above in the description of the system 600, as described above. s Greater than -0.02, n s Shape-fitting interfaces with refractive indices less than +0.02 can be positioned between the FOE and the sample and between the SOE and the sample.

[0317] The terms “measure” and “perceive” are used synonymously in this specification. Similarly, the terms “perceived data” and “measured data” (or “measured data”) are used interchangeably.

[0318] For clarity, it should be understood that certain features of the Disclosure described in the context of separate embodiments may be provided in combination in a single embodiment. Conversely, for brevity, various features of the Disclosure described in the context of a single embodiment may be provided separately, in any preferred partial combination, or in a manner suitable for any other described embodiment of the Disclosure. Features described in the context of an embodiment should not be considered essential features of that embodiment unless specifically stated otherwise.

[0319] While steps of a method in some embodiments may be described in a specific sequence, the methods disclosed may include some or all of the described steps that are performed and / or occur in different sequences. The methods disclosed may include some or all of the described steps. No particular step of the disclosed method should be considered an essential step of the method unless otherwise specified.

[0320] While this disclosure is described with regard to its specific embodiments, it is evident that a number of alternative, modified, and transformed forms may exist that are apparent to those skilled in the art. Therefore, this disclosure encompasses all such alternative, modified, and transformed forms that fall within the scope of the appended claims. It should be understood that this disclosure is not necessarily limited to the structure and arrangement of the components described herein and / or their application to the details of the method. Other embodiments may be implemented, and embodiments may be performed in various ways.

[0321] The expressions and terms used herein are for illustrative purposes only and should not be construed as limiting. No reference or specification of any reference in this application should be construed as an admission that such reference is available as prior art to this disclosure. The headings used herein are for the purpose of facilitating the understanding of this specification and should not necessarily be construed as limiting.

Claims

1. An optical system for measuring a sample, wherein the sample has a refractive index n s A substrate having two or more internal facets, wherein the internal facets are embedded within the substrate, nominally parallel, and substantially perpendicular to a first flat surface on the outside of the sample, and the system comprises a first optical element (FOE) and an optical setup including a light source, optical instruments, and a light-sensing component, The aforementioned FOE is n s It has a refractive index approximately equal to and comprises an outer, flat first surface and an outer, flat second surface that is opposite to the first surface of the FOE and is inclined at a first acute angle of inclination with respect to the first surface, The optical setup is configured to enable positioning the sample and / or the FOE such that, when the second surface of the sample is adjacent to the first surface of the sample and positioned in such a manner, a plurality of first light beams that can be generated by the light source collide substantially normal to the first surface of the FOE. The FOE is further configured to focus the second plurality of light beams, which are formed when the first plurality of light beams pass through the FOE, penetrate into the sample, are reflected from the internal facets, and then exit the sample, onto the photosensing component, thereby enabling the measurement of angular deviations between the second plurality of light beams. A system in which the angular deviation between the second plurality of light beams represents a deviation from the parallelism between the internal facets.

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

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

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

5. The system according to claim 1, wherein the optical setup is configured to enable positioning the sample and the FOE such that a first region on the first surface of the sample is in full contact with the second surface of the FOE, the first region being defined by a section of the sample having the internal facets.

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

7. The system according to claim 1, wherein the FOE is a prism.

8. The system according to claim 1, wherein the optical setup further comprises a translationable slit-type optical mask or aperture-type optical mask and / or a plurality of shutters configured to allow inspection of the internal facets one at a time.

9. The system according to claim 4, wherein the sensed data includes the measured intensity of pixels constituting a spot, each induced by the second plurality of light beams on the image sensor.

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

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

12. The aforementioned calculation module, Quantity ε avg and / or ε max It is configured to calculate ε avg but, [Math 1] Equivalent to ε max but, [Math 2] or [Math 3] Equivalent to, [Math 4] and [Math 5] The system according to claim 10, wherein is a set of two-dimensional vectors specifying the positions of the i-th and j-th 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 a focusing lens or focusing lens assembly configured to focus the returned light beam onto the image sensor.

13. The system according to claim 10, wherein the optical setup further comprises a translationable slit-type or aperture-type optical mask and / or a plurality of shutters configured to allow inspection of the internal facets one at a time, and the calculation module is configured to calculate the deviation from parallelism between pairs of internal facets from two or more internal facets.

14. The calculation of the deviation from the parallelism between pairs of the internal facets includes calculating a deviation of a pitch {ε ij,p} i,j and / or a roll {ε ij,r}, i,j where the indices i and j range over pairs of different internal facets, and ε ij,p and ε ij,r are the pitch and roll deviations between the i-th and j-th internal facets among the internal facets, respectively. The system according to claim 13

15. The aforementioned ε ij,p and the ε ij,r Each of them is 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 • Calculated via f), δ ij,p However, this is the pitch deviation between the i-th light beam of the second plurality of light beams, which is induced by reflection from the i-th internal facet, and the j-th light beam of the second plurality of light beams, which is induced by reflection from the j-th internal facet, δ ij,r However, this is the roll deviation between the i-th light beam and the j-th light beam among the second plurality of light beams. [Math 6] The method according to claim 14, wherein is a set of two-dimensional vectors that specify the position of a spot on an image sensor induced by the second plurality of light beams, wherein the index k indicates the light beam, N is the number of internal facets, and f is the focal length of a focusing lens or focusing lens assembly configured to focus the second plurality of light beams onto the image sensor.

16. The system according to claim 1, wherein the optical setup is configured to enable positioning the sample and / or the FOE such that a first region on the first surface of the sample is in full contact with the second surface of the FOE, the first region being defined by a section of the sample having the internal facets.

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

18. The system according to claim 1, wherein the optical setup comprises an autocollimator configured to generate the first plurality of light beams and to focus the second plurality of light beams onto the photosensing component.

19. The method according to any one of claims 1 to 18, wherein the second plurality of light beams include light beams returned from the sample via the first surface of the sample and via the FOE.

20. The system according to claim 19, wherein the sample comprises an outer, flat second surface opposite to the first surface of the sample, and the returned light beam is reflected from the second surface of the sample before it exits the sample through the first surface of the sample.

21. The method according to claim 20, wherein the internal facets of the sample are perpendicular to the first surface of the sample, and the second surface of the sample is parallel to the first surface of the sample.

22. The adjacent internal facets of the sample are spaced at regular intervals, and the first tilt angle is approximately (90° - arctan(2d) 1 / d 2 )) is equal to d 1 However, this is the distance between the first surface of the sample and the second surface of the sample, and d 2 The method according to claim 21, wherein the distance is between adjacent internal facets of the sample.

23. The system according to any one of claims 1 to 15, wherein the sample comprises an outer, flat second surface facing the first surface of the sample, and the second plurality of light beams include light beams emanating from the sample through the second surface of the sample.

24. n s The second optical element (SOE) further comprises a first outer, flat surface having a refractive index approximately equal to , and a second outer, flat surface facing the first surface of the SOE and inclined at a second acute angle of inclination with respect to the first surface, The system according to claim 23, wherein the optical setup is further configured to enable positioning the sample and / or the SOE such that the second surface of the SOE is adjacent to the second surface of the sample.

25. The system according to claim 24, wherein the second plurality of light beams include light beams that exit the sample via the second surface of the sample, pass through the SOE, and then exit the SOE via the first surface of the SOE.

26. The system according to claim 25, wherein the optical setup is further configured to enable positioning the sample and / or the SOE such that a first region on the first surface of the sample is in full contact with the second surface of the FOE, a second region of the sample opposite to the first region is in full contact with the second surface of the SOE, and the first region and the second region are defined by the section of the sample having the internal facets.

27. The system according to claim 26, wherein the internal facets of the sample are perpendicular to the first surface of the sample, and the second surface of the sample is parallel to the first surface of the sample.

28. The system according to claim 27, wherein the second inclination angle is approximately equal to the first inclination angle such that each of the second plurality of light beams exits the SOE in a direction substantially normal to the first surface of the SOE.

29. The adjacent internal facets of the sample are spaced apart at regular intervals, and each of the first and second inclination angles is approximately (90° - arctan(d) 1 / d 2 )) is equal to d 1 However, this is the distance between the first surface of the sample and the second surface of the sample, and d 2 The system according to claim 28, wherein the distance between adjacent internal facets of the sample is the distance between them.

30. The system according to claim 24, wherein the SOE is a prism.

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

32. An optical method for verifying the parallelism between internal facets of a sample, Refractive index n s A step of providing a sample comprising a light-transmitting substrate having, and two or more internal facets embedded in the substrate, nominally parallel, and substantially perpendicular to a first flat surface on the outside of the sample, n s A step of providing a first optical element (FOE) having a refractive index approximately equal to , wherein the FOE comprises an outer, flat first surface and an outer, flat second surface facing the first surface of the FOE and inclined at a first acute angle of inclination with respect to the first surface. The steps include positioning the sample and the FOE such that the second surface of the FOE is adjacent to the first surface of the sample, The steps include projecting a first plurality of light beams onto the first surface of the FOE in a direction substantially normal to the first surface of the FOE, The steps include acquiring a second set of light beams, each of which passes through the FOE, is transmitted into the sample, is reflected once from the internal facets, and then exits the sample; The step of sensing the second set of light beams, A method comprising the step of calculating at least one deviation from parallelism between at least some of the internal facets based on the sensed data.

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