Optical based verification of surface orientation

Abstract

An optical-based method for verifying an angle between external flat surfaces of a sample is disclosed herein. The method comprises: (i) providing a sample comprising an external flat first surface and an external flat second surface, the second surface nominally tilted at a nominal angle with respect to the first surface; (ii) generating a first incident light beam (LB) directed to the first surface and a second incident LB parallel to the first incident LB; (iii) obtaining a first return LB by reflecting the first incident LB off the first surface; (iv) obtaining a second return LB by folding the second incident LB at the nominal angle, reflecting the folded LB off the second surface, and folding the reflected LB at the nominal angle; (v) measuring a first angular deviation between the return LBs; and (vi) deriving an actual tilt angle between the first surface and the second surface based at least on the measured first angular deviation.

Description

Technical Field

[0001] This disclosure generally relates to methods and systems for measuring the surface of samples. Background Technology

[0002] Optical components, such as glass prisms, increasingly require high angular tolerances between their surfaces. Meeting these tolerances necessitates high-precision measurements to verify the angles between surfaces, which in turn requires high-end optical components and complex alignment and calibration processes. Therefore, there is an unmet need in the art for a simple and easily implemented measurement technique that avoids the use of high-end optical components, thus meeting the demands of mass production. Summary of the Invention

[0003] Various aspects of this disclosure, according to some embodiments thereof, relate to methods and systems for measuring the surface of a sample. More specifically, but not exclusively, various aspects of this disclosure, according to some embodiments thereof, relate to optical-based methods and systems for measuring the outer surface of a sample.

[0004] This application discloses a rapid, simple, and accurate method and system for measuring the tilt of an external flat surface of a sample relative to one or more other external flat surfaces of the sample. To achieve this, two parallel light beams (LBs) can be used: a first LB is incident on a first external flat surface of the sample. A second LB is redirected to nominally incident on a second external flat surface of the sample at the same angle of incidence as the first LB, the tilt angle of which is verified relative to the first surface. Then, after the second reflected LB has been redirected again, the angular deviation between the reflected LBs is measured. Advantageously, according to some embodiments of the disclosed technology, a collimating light source, a light sensor (or image sensor), a light folding component for redirecting the second LB, and an orientation base structure for orienting the sample are sufficient to verify the tilt of the external flat surface.

[0005] Therefore, according to aspects of some embodiments, an optical-based method is provided for verifying the angle between the outer flat surfaces of a sample. The method includes:

[0006] - Provide a sample comprising an externally flat first surface and an externally flat second surface, the second surface being nominally tilted relative to the first surface at a nominal tilt angle (intended to be tilted by design and manufacture).

[0007] - Generate a first incident beam (LB) that is directed to the first surface and a second incident beam (LB) that is parallel to the first incident beam (LB).

[0008] - The first return LB is obtained by reflecting the first incident LB away from the first surface.

[0009] - By folding the second incident LB at a light folding angle nominally equal to the nominal tilt angle, reflecting the folded LB away from the second surface, and folding the reflected LB at the light folding angle, a second returning LB is obtained.

[0010] - Measure the first angular deviation of the second return LB relative to the first return LB.

[0011] - The actual tilt angle of the second surface relative to the first surface is derived at least based on the measured first angular deviation.

[0012] According to some embodiments of this method, the derived actual tilt angle is equal to α + δ / 2, or approximately equal to α + δ / 2 (e.g., the derived actual tilt angle is between α + 0.475·δ and α + 0.525·δ, between α + 0.45·δ and α + 0.55·δ, or even between α + 0.4·δ and α + 0.6·δ, each possibility corresponding to a separate embodiment). α is the nominal tilt angle. δ is a measurement of the first angular deviation.

[0013] According to some embodiments of the method, the first incident LB is guided to the first surface in a manner perpendicular to the first surface.

[0014] According to some embodiments of the method, folding is achieved using a light folding component (LFC), which is or includes a prism, one or more mirrors and / or a diffraction grating.

[0015] According to some implementations of this method, the optical folding angle is insensitive to changes in the pitch of the LFC.

[0016] According to some embodiments of the method, the LFC is or includes a pentaprism or similar prism, or a pair of mirrors or similar mirrors arranged at an angle to each other.

[0017] According to some embodiments of the method, the sample is or includes glass, polymer, metal, crystal and / or combinations thereof.

[0018] According to some embodiments of this method, the sample is a prism.

[0019] According to some implementations of this method, the second surface does not share a common edge with the first surface.

[0020] According to some implementations of the method, the first incident LB and the second incident LB are complementary parts of a single collimating LB.

[0021] According to some embodiments of the method, a first incident LB and a second incident LB are prepared by blocking one or more portions of a single collimating LB.

[0022] According to some implementations of this method, a single collimation LB is multicolored.

[0023] According to some implementations of this method, a single collimated LB is a laser beam.

[0024] According to some implementations of this method, an automatic collimator is used to measure the first angular deviation.

[0025] According to some embodiments of this method, the first angular deviation between the returned LBs is equal to or approximately equal to Δu / f. Δu is the difference between the coordinates of the first point and the corresponding coordinates of the second point on the photosensitive surface of the autocollimator. f is the focal length of the collimating lens of the autocollimator. The first point is formed by the first returned LB, and the second point is formed by the second returned LB.

[0026] According to some embodiments of the method, the method also includes an initial calibration phase in which the system is calibrated using a gold standard sample.

[0027] According to some implementations of this method, the nominal tilt angle is an obtuse angle.

[0028] According to some implementations of this method, the nominal tilt angle is an acute angle.

[0029] According to some embodiments of the method, wherein the nominal tilt angle is 90° and the sample includes an external flat third surface parallel to the first surface, the method further includes, after measuring the first angular deviation:

[0030] - Flip the sample to reverse the first and third surfaces while maintaining the nominal orientation of the second surface relative to the LFC.

[0031] - Prepare a third incident LB that is guided to the third surface, and a fourth incident LB that is parallel to the third incident LB.

[0032] -A third return LB is obtained by reflecting the third incident LB away from the third surface.

[0033] - By folding the fourth incident LB at a light folding angle nominally equal to the nominal tilt angle, causing the fourth incident LB to reflect away from the second surface, and folding the fourth incident LB at the light folding angle, a fourth return LB is obtained.

[0034] - Measure the second angular deviation of the fourth return LB relative to the third return LB.

[0035] In the derivation of the actual tilt angle, the deviation of the measured second angle was also considered.

[0036] According to some implementations of this method, the uncertainty of the parallelism between the first and third surfaces is less than the required measurement accuracy of the actual tilt angle.

[0037] According to some embodiments of the method, the derived actual tilt angle is equal to χ + (δ1 – δ2) / 4, or approximately equal to χ + (δ1 – δ2) / 4 (for example, the derived actual tilt angle is between χ + 0.235·(δ1 – δ2) and χ + 0.265·(δ1 – δ2), between χ + 0.225·(δ1 – δ2) and χ + 0.275·(δ1 – δ2), or even between χ + 0.2·(δ1 – δ2) and χ + 0.3·(δ1 – δ2). Each possibility corresponds to a separate embodiment). χ is the nominal tilt angle. δ1 is the measured first angular deviation and δ2 is the measured second angular deviation.

[0038] According to some embodiments of the method, the method further includes: suppressing internal reflections from the fourth surface when the sample includes an externally flat fourth surface that is nominally parallel to the second surface.

[0039] According to aspects of some embodiments, an optical-based system is provided for verifying the angle between the outer flat surfaces of a sample. The system includes:

[0040] - A folding element (LFC) is nominally configured to fold light incident on the folding element at a nominal tilt angle defined by a first external flat surface of the sample and a second external flat surface of the sample.

[0041] - Illumination and collection arrangement (ICA), including:

[0042] A light generating component that (a) projects a first incident beam (LB) onto a first surface to generate a first returning LB by reflection from the first surface, and (b) projects a second incident LB parallel to the first incident LB onto an LFC to generate a second returning LB by reflection from a second surface and re-passing through the LFC.

[0043] At least one sensor configured to measure a first angular deviation between a first return LB and a second return LB; and / or an eyepiece assembly configured to enable manual measurement of the first angular deviation.

[0044] The measured first angular deviation indicates the actual tilt angle of the second surface relative to the first surface.

[0045] According to some implementations of the system, the light generating components include a light source and optical devices.

[0046] According to some embodiments of the system, the system also includes an orientation base structure configured to orient the sample such that the first incident LB is incident normally (i.e., perpendicularly) on the first surface, and / or such that a folded LB obtained by folding a second incident LB by LFC is incident nominally normally on the second surface.

[0047] According to some embodiments of the system, the system includes at least one sensor and a calculation module configured to calculate the actual tilt angle of the second surface relative to the first surface based at least on the measured first angular deviation.

[0048] According to some embodiments of the system, the system includes at least one sensor, and the ICA is or includes an automatic collimator. The automatic collimator includes a light source and at least one sensor.

[0049] According to some embodiments of the system, the ICA also includes a pair of blocking elements configured to selectively block each of the first incident LB and the second incident LB. According to some such embodiments, the blocking elements are shutters that completely block the light beam incident upon them.

[0050] According to some implementations of the system, the LFC includes a prism, one or more mirrors and / or a diffraction grating.

[0051] According to some implementations of the system, the light folding angle of the LFC is insensitive to changes in the pitch of the LFC.

[0052] According to some implementations of the system, the LFC is or includes a pentaprism or similar prism, or a pair of mirrors or similar mirrors arranged at an angle to each other.

[0053] According to some implementations of the system, the system is configured to facilitate the flipping of samples.

[0054] According to some embodiments of the system, the system includes at least one sensor and a computing module. The nominal tilt angle is 90°, and the sample also includes an external flat third surface parallel to the first surface. The computing module is configured to calculate the actual tilt angle by additionally considering a measured second angular deviation of the fourth return LB relative to the third return LB. When the sample is flipped such that the first and third surfaces are reversed and the nominal orientation of the second surface relative to the LFC is maintained: (a′) the third return LB is obtained by projecting a third incident beam onto the third surface of the sample to generate a third return LB through reflection from the third surface; and (b′) the fourth return LB is obtained by projecting a fourth incident LB parallel to the third incident LB onto the LFC to generate a fourth return LB through folding of the fourth incident LB by the LFC, reflection from the second surface, and re-passing through the LFC.

[0055] According to some implementations of the system, the calculation module is also configured to calculate the uncertainty in the obtained value of the actual tilt angle, taking into account at least the manufacturing tolerances and defects of LFC and ICA.

[0056] According to some implementations of the system, the system includes an oriented foundation structure, and the calculation module is configured to calculate the uncertainty in the calculated value of the actual tilt angle by additionally considering the manufacturing tolerances and defects of the oriented foundation structure.

[0057] According to some embodiments of the system, the light generating component includes a light source and optical devices. The light source is configured to generate a single light beam (LB). The optical devices are configured to collimate the single LB.

[0058] According to some implementations of the system, the first incident LB and the second incident LB are complementary parts of the collimation LB.

[0059] According to some implementations of this system, the light source is a multi-color light source.

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

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

[0062] According to some implementations of the system, at least one sensor includes a light sensor and / or an image sensor (e.g., a camera device).

[0063] According to some embodiments, a method for manufacturing a sample having a pair of external flat surfaces disposed relative to each other at a nominal angle is provided. The method includes the following stages:

[0064] - Provide original samples.

[0065] - Process the original sample to obtain a processed sample comprising an externally flat first surface and an externally flat second surface, the second surface being set at a test angle relative to the first surface.

[0066] - The test angle is measured using the optical-based method described above.

[0067] - If the difference between the test angle and the nominal angle is greater than a predefined difference, the processed sample is subjected to further processing to obtain a reprocessed sample.

[0068] - Repeat the measurement phase and, if necessary, repeat the reprocessing phase until the difference between the test angle and the nominal angle of the reprocessed sample is less than a predefined difference.

[0069] Some embodiments of this disclosure may include some, all, or none of the advantages described above. One or more other technical advantages may be apparent to those skilled in the art from the accompanying drawings, specification, and claims included herein. Furthermore, while specific advantages have been set forth above, various embodiments may include all, some, or none of the listed advantages.

[0070] Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure pertains. In case of conflict, the patent specification (including definitions) shall prevail. Unless the context clearly indicates otherwise, the indefinite articles “a” and “an” as used herein mean “at least one” or “one or more”.

[0071] Unless otherwise expressly stated, as is apparent from this disclosure, it should be understood that, according to some embodiments, terms such as “processing,” “computing,” “calculating,” “determining,” “estimating,” “evaluating,” “measuring,” etc., may refer to the actions and / or processing of a computer or computing system or similar electronic computing device that manipulates and / or converts data represented as physical (e.g., electronic) quantities in the registers and / or memory of the computing system into other data similarly represented as physical quantities in the memory, registers, or other such information storage, transmission, or display devices of the computing system.

[0072] Embodiments of this disclosure may include means for performing the operations described herein. Such means may be specifically constructed for a desired purpose, or may include a general-purpose computer selectively activated or reconfigured by a computer program stored in a computer. Such a computer program may be stored in a computer-readable storage medium, such as, but not limited to, any type of disk, including floppy disks, optical disks, CD-ROMs, magneto-optical disks, read-only memory (ROM), random access memory (RAM), electrically programmable read-only memory (EPROM), electrically erasable and programmable read-only memory (EEPROM), magnetic cards or optical cards, or any other type of medium suitable for storing electronic instructions and capable of being coupled to a computer system bus.

[0073] The processes and displays presented herein are not inherently associated with any particular computer or other device. Various general-purpose systems may be used with the programs taught herein, or it may prove convenient to construct more specialized devices to perform the desired methods. The desired structures for various such systems appear in the description below. Furthermore, implementations of this disclosure are described without reference to any particular programming language. It should be understood that the teachings of this disclosure described herein can be implemented using various programming languages.

[0074] Various aspects of this disclosure can be described within the general context of computer-executable instructions, such as program modules, that are executed by a computer. Generally, program modules include routines, programs, objects, components, data structures, etc., that perform a specific task or implement a specific abstract data type. The disclosed implementations can also be implemented in a distributed computing environment, wherein the task is performed by a remote processing device linked via a communication network. In a distributed computing environment, program modules can reside on both local computer storage media and remote computer storage media, including memory storage devices. Attached Figure Description

[0075] Some embodiments of this disclosure are described herein with reference to the accompanying drawings. This description, together with the drawings, enables those skilled in the art to understand how some embodiments can be implemented. The drawings are for illustrative purposes and do not attempt to show structural details of the embodiments in more detail than necessary for a basic understanding of 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.

[0076] In the attached diagram:

[0077] Figure 1A An optical-based system for measuring the external flatness of a sample during sample inspection, according to some embodiments, is schematically depicted.

[0078] Figure 1B Presented according to some implementation methods Figure 1A A schematic perspective view of the sample during its inspection;

[0079] Figure 1C The illustration schematically depicts a configuration according to some implementation methods. Figure 1A The point on the photosensitive surface of the sensor in the system;

[0080] Figure 2A and Figure 2B An optical-based system is schematically depicted for verifying the perpendicularity of one outer flat surface of a sample relative to two other parallel outer flat surfaces of the sample during sample inspection. Figure 1A The specific implementation method of the system corresponds to;

[0081] Figure 2C and Figure 2D The illustration schematically depicts a configuration according to some implementation methods. Figure 2A and Figure 2B The point on the photosensitive surface of the sensor in the system;

[0082] Figure 3 An optical-based system for measuring the external flatness of a sample during sample inspection is schematically depicted, and this system is related to... Figure 1A The specific implementation of the system corresponds to the light folding component of the system, which is a prism;

[0083] Figure 4 An optical-based system for measuring the external flatness of a sample during sample inspection is schematically depicted, and this system is related to... Figure 1A The specific implementation of the system corresponds to the optical folding component of the system, which is a mirror;

[0084] Figure 5 A flowchart is presented showing an optical-based method for measuring the external flatness of a sample, according to some embodiments; and

[0085] Figure 6 A flowchart is presented of an optical-based method, according to some embodiments, for verifying the perpendicularity of one external flat surface of a sample relative to two other parallel external flat surfaces of the sample. Detailed Implementation

[0086] Referring to the accompanying specifications and drawings will provide a better understanding of the principles, uses, and implementation methods of the teachings herein. After carefully reading the specifications and drawings presented herein, those skilled in the art will be able to implement the teachings without excessive effort or experimentation. In the drawings, the same reference numerals consistently denote the same parts.

[0087] In the specification and claims of this application, the words “comprising” and “having” and their forms are not limited to members of the list associated with the words.

[0088] As used herein, the term "about" can be used to specify a quantity or parameter (e.g., the length of an element) within a continuous range of values ​​near (and including) a given (stated) value. According to some embodiments, "about" can specify a parameter value between 80% and 120% of a given value. For example, stating "the length of the element is about 1 m" is equivalent to stating "the length of the element is between 0.8 m and 1.2 m." According to some embodiments, "about" can specify a parameter value between 90% and 110% of a given value. According to some embodiments, "about" can specify a parameter value between 95% and 105% of a given value.

[0089] As used herein, the terms “substantially” and “about” may be used interchangeably in some implementations.

[0090] For ease of description, a three-dimensional Cartesian coordinate system is introduced in some figures. Note that the orientation of the coordinate system relative to the depicted object can change as the figure changes. Furthermore, the symbol ⊙ can be used to indicate an axis pointing "outside the page," while the symbol... It can be used to represent an axis pointing "inside the page".

[0091] In the accompanying drawings, optional elements and optional stages (in the flowchart) are depicted by dashed lines.

[0092] system

[0093] According to some aspects of the implementation, an optical-based system is provided for measuring the external flat surface of a sample. Figure 1AAn optically based system 100, according to some embodiments, is schematically depicted. The optically based system 100 is configured to verify the angle between two outer flat surfaces of a sample. Figure 1A A side view of system 100 and sample 10 according to some embodiments is provided. (It should be understood that sample 10 does not constitute part of system 100.) Sample 10 is shown as being examined by system 100. Sample 10 can be any opaque or partially transparent element having two or more reflective flat (outer) surfaces arranged at (non-zero) angles relative to each other. According to some embodiments, sample 10 can be made of glass, polymer, metal, crystal, and / or combinations thereof. According to some embodiments, sample 10 can be an optical element, such as a prism, waveguide, or beam splitter. According to some embodiments, a prism can be shaped as a polyhedron. According to some embodiments, such as Figure 1A The cross section of sample 10, which is depicted and taken parallel to the zx plane, can be defined as a polygon.

[0094] Sample 10 includes an outer flat first surface 12a (i.e., a first outer surface, which is flat) and an outer flat second surface 12b (i.e., a second outer surface, which is flat). Sample 10 is manufactured to present a nominal tilt angle α between the first surface 12a and the second surface 12b. However, due to manufacturing defects, the actual tilt angle between the first surface 12a and the second surface 12b (in...) Figure 1A The angle marked as α′ is usually different from the nominal tilt angle α. Figure 1A The diagram shows a dashed line L that intersects the second surface 12b and is inclined relative to the first surface 12a at a nominal tilt angle α. The dashed line L indicates the expected tilt of the second surface 12b. The nominal tilt angle α can be an acute angle (i.e., α < 90°), an obtuse angle (i.e., α > 90°), or equal to 90°.

[0095] Figure 1A The diagram also shows a (straight) dashed line H extending parallel to the first surface 12a and intersecting the second surface 12b. The supplementary angle of the nominal tilt angle α (denoted as β, i.e., β = 180° - α) spans between the second surface 12b and the dashed line H.

[0096] According to some embodiments, system 100 includes a light folding component (LFC) 102 and an illumination and collection arrangement (ICA) 104. System 100 may also include a controller 108 functionally associated with and configured to control the operation of the ICA 104. According to some embodiments, and as... Figure 1AAs depicted, the ICA 104 includes a light source 112 (or multiple light sources) and a sensor 114 (or multiple sensors), and optionally includes an optical device 118. According to some embodiments, the sensor 114 is a light sensor or an image sensor (or multiple sensors including one or more light sensors and / or one or more image sensors, such as a camera device). According to [not specified] Figure 1A In some alternative implementations depicted, ICA 104 includes an eyepiece assembly instead of sensor 114, thereby configuring ICA 104 for visual determination of the actual tilt angle (i.e., by eye). Light source 112 and optical device 118 are collectively referred to as the "light generating assembly".

[0097] As described in detail below, the ICA 104 is configured to output a pair of parallel light beams (LBs): the first LB 105a (also known as the "first incident LB"); in Figure 1A (indicated by a pair of parallel rays) and the second LB 105b (also known as "second incident LB"; in Figure 1A (Indicated by a pair of parallel rays). According to some such embodiments, optical device 118 may be configured to collimate the light generated by light source 11, thereby producing (parallel) incident LBs 105a and 105b. According to such embodiments, optical device 118 may include a collimating lens or collimating lens assembly (not shown). According to some embodiments, incident LBs 105a and 105b may form complementary portions of a collimated beam (which has been focused by a collimating lens or collimating lens assembly). Alternatively, according to some embodiments, incident LBs 105a and 105b may be spaced apart (and parallel). According to some such embodiments, optical device 118 may also include one or more filters (e.g., light-absorbing filters or opaque plates), and / or one or more beam splitters, and optionally, one or more mirrors (not shown), optical device 118 being configured to produce a pair of spaced apart and parallel LBs from the collimated LBs.

[0098] According to some embodiments, the optical device 118 may include a plurality of blocking elements (e.g. Figure 2A and Figure 2BThe paired blocking elements depicted herein are configured such that each of the incident LBs 105 can be selectively blocked, thereby enabling the sensing of each of the returned LBs caused by the first incident LB 105a and the second incident LB 105b, respectively. As used herein, the term "blocking element" in reference to optical elements is broadly interpreted to include both opaque elements (e.g., shutters) and filtering elements (e.g., spectral filters) that can be controlled to open and close, the opaque elements being configured to block light beams incident upon them (when closed), and the filtering elements being configured to completely or partially block one or more portions of the spectrum (e.g., the visible spectrum).

[0099] According to some embodiments, the light source 112 can be configured to produce multicolor light. According to some such embodiments, the spectrum of light can be controllable. According to some embodiments, the light source 112 can be configured to produce monochromatic light. In this regard, it should be noted that when the LFC 102 is a prism and a second incident light LB 105b is generated to be incident non-perpendicularly on the prism (e.g., when a first incident light LB 105a is generated to be incident non-perpendicularly on the first surface 12a), monochromatic light is preferably used.

[0100] According to some embodiments, ICA 104 is or includes an autocollimator (i.e., the light source 112, sensor 114, and some or all of the optical devices 118 constitute the components of the autocollimator). According to some embodiments, the incident LB 105 constitutes adjacent sub-beams of a single, wide, and collimated LB generated by the autocollimator. According to such an embodiment, the optical device 118 may include a filter configured to transmit the two sub-beams (e.g., incident LB 105) of the collimated LB prepared by the autocollimator and incident on the filter (maintaining the parallelism of the two sub-beams upon exiting the filter).

[0101] According to some embodiments, the light source 112 can be configured to generate a collimated laser beam. According to some such embodiments, the optical device 118 may include a beam expander (not shown) configured to increase the diameter of the laser beam such that the expanded laser beam can be simultaneously incident on the sample 10 and the LFC 102. In such embodiments, the first incident LB 105a and the second incident LB 105b may constitute complementary portions of the laser beam. Alternatively, the optical device 118 may include a beam splitter and optics configured to split the laser beam into a pair of parallel (spaced-apart) sub-beams: a first sub-beam and a second sub-beam constituting the first incident LB 105a and the second incident LB 105b, respectively. According to some such embodiments, optical device 118 can be configured to recombine the returned sub-beams (i.e., the first returned LB 133a and the second returned LB 133b) such that each of the sub-beams is redirected to a single photosensor (i.e., sensor 114 according to some embodiments thereof) and focused (e.g., using a lens or lens arrangement) on the photosensitive surface of the photosensor. Ideally, if the second sub-beam (after being redirected by LFC 122 and transmitted into sample 10) is incident perpendicularly onto the inner facet 14, the recombinated sub-beams will form a collimated (second) laser beam, and the two points formed on the photosensor by the returned sub-beams will overlap. According to some other embodiments, two photosensors can be employed such that the distance and relative orientation between the two photosensors are known. In such embodiments, each of the returned sub-beams can be directed to a different photosensor than the two photosensors.

[0102] According to some embodiments, ICA 104 can be configured for interferometric measurement: the light source 112, some or all of the optical devices 118, and the sensor 114 constitute the components of the interferometric measurement apparatus, as described below. In such an embodiment, the light source 112 can be configured to generate a coherent plane wavefront. The optical devices 118 can be configured to divide the generated wavefront into two wavefronts: a first (coherent plane) incident wavefront and a second (coherent plane) incident wavefront constituting the first incident LB 105a and the second incident LB 105b, respectively.

[0103] According to some embodiments, LFC 102 is or includes a prism, one or more mirrors and / or a diffraction grating. According to some embodiments, LFC 102 is a pentaprism or a similar prism that is insensitive to pitch changes (in the sense that its light folding angle remains unchanged when the pitch of the LFC is slightly changed, i.e., when the LFC 102 is slightly rotated about the y-axis).

[0104] According to some embodiments, system 100 may further include an orientation base structure 120 for orienting sample 10 relative to ICA 104. As a non-limiting example, orientation base structure 120 may be in the form of a stage 122 mounted on a base 124. Stage 122 is configured for mounting a sample, such as sample 10, thereon. Base 124 is configured to orient and optionally translate stage 122. According to some embodiments, base 124 may be configured to provide manipulation of sample 10 in each of the six degrees of freedom (i.e., translation in any direction, rotation about the yaw axis, and (at least limited) rotation about the pitch and roll axes). Specifically, the orientation base structure 120 can be configured to orient the sample 10 such that the first incident LB 105a will be incident perpendicularly onto the first surface 12a, and the folded LB 113b obtained by the second incident LB 105b incident on the LFC 102 will be incident nominally perpendicularly onto the second surface 12b. According to some embodiments, the orientation base structure 120 can be functionally associated with and configured to be controlled by the controller 108.

[0105] As used herein, the terms "nominally" and "ideally" are interchangeable according to some embodiments. An object can be said to "nominally" exhibit (i.e., be characterized by) an inherent characteristic when it is designed and manufactured to exhibit an inherent characteristic, such as the angle of inclination between the flat surfaces of a sample, but in practice, due to manufacturing tolerances, the object may actually only imperfectly exhibit that characteristic. The same applies to extrinsic characteristics of an object, such as the direction of light propagation of a beam. In this case, it should be understood that the object has been intentionally prepared or otherwise manipulated to ideally exhibit that characteristic, but in practice, due to inherent defects, such as in the apparatus used for preparation, the object may actually only imperfectly exhibit that characteristic.

[0106] In operation, the first incident LB 105a is directed to sample 10, and the second incident LB 105b is directed to LFC 102. According to some embodiments, and as... Figure 1A As depicted, the first incident LB 105a is incident on the first surface 12a perpendicular to it. The first incident LB 105a (or at least a portion of the first incident LB 105a) is reflected away from the first surface 12a as indicated by the first return LB 125a and is sensed by the sensor 114.

[0107] The second incident LB 105b is directed to LFC 102. LFC 102 is nominally configured to fold the second incident LB 105b at a nominal tilt angle α. More precisely, LFC 102 is configured to "fold" (i.e. redirect) the second incident LB 105b such that the folded LB 113b (obtained by folding the second incident LB 105b) is nominally guided at a nominal tilt angle α relative to the second incident LB 105b and (nominally) perpendicular to the second surface 12b. In practice, due to manufacturing defects, the actual optical folding angle α″ of LFC 102 may deviate slightly from the nominal tilt angle α. When the uncertainty of the optical folding angle of LFC 102 (due to manufacturing tolerances) is significantly lower than the accuracy of the actual tilt angle of the second surface 12b to be determined, the uncertainty of the optical folding angle can be ignored (i.e., it can be assumed that LFC 102 folds the second incident LB 105a with an accurate nominal tilt angle α). Otherwise, the uncertainty of the optical folding angle will (non-negligibly) contribute to the total uncertainty in the measurement of the actual tilt angle unless the nominal tilt angle is equal to 90°. In the case of a nominal tilt angle of 90°, the deviation of the actual folding angle can be reduced by performing additional measurements with the sample flipped, as follows: Figure 2A and Figure 2B Description and Figure 6 As detailed in the description.

[0108] To keep the accompanying drawings concise, only two rays of each beam are typically indicated. Furthermore, the depiction of the beams is schematic, and it should be understood that the depicted beams may be wider or narrower than those drawn. Thus, for example, according to some embodiments, the first incident LB 105a may be incident on the entire first surface 12a, and / or the second incident LB 105b may be incident on the entire light-receiving surface of the LFC 102.

[0109] Folded LB 113b is incident on the second surface 12b at an angle θ. The angle is measured clockwise from the viewpoint of the reader of the reading diagram. Angles greater than 180° are set negative by subtracting 360°. Thus, as a non-limiting example intended to facilitate description by making it more concrete, in Figure 1A In this case, the angle of incidence θ is negative and the angle of return (i.e., the angle of reflection) is positive. More precisely, it is shown that the light ray crosses counterclockwise from the dashed line B (which indicates the normal to the second surface 12b) to the ray 113b1 (indicating...). Figure 1A The incident angle θ of one of the two rays from the folded LB 113b. The tilt angles α and α′ are measured clockwise from the first surface 12a (as a non-limiting example, intended to facilitate description, in...). Figure 1AIn the diagram, α′ is shown as greater than α. The nominal tilt angle α crosses clockwise from the first surface 12a to the dashed line L. The actual tilt angle α′ crosses clockwise from the first surface 12a to the second surface 12b.

[0110] The incident angle θ depends on the deviation Δα′ = α - α′ (i.e., the deviation of the tilt of the second surface 12b from the nominal tilt) and the deviation Δα″ = α - α″ (i.e., the deviation of the actual optical folding angle of LFC 102 from α). In the absence of any defects in system 100 (i.e., α″ = α), the incident angle θ will be equal to Δα′. In other words, the incident angle θ equals Δα′, and its accuracy depends on the uncertainty of the actual optical folding angle α″ and any other relevant uncertainties in the parameters of LFC 102, ICA 104, and the orientation base structure 120 (i.e., its orientation accuracy). Specifically, system 100 is configured such that the output LB 113b is nominally normal (i.e., perpendicularly) incident on the second surface 12b when Δα′ = 0. Figure 1A The value in parentheses indicates the magnitude of Δα′ (i.e., |Δα′|, where the parentheses indicate the absolute value).

[0111] Folded LB 113b (or at least a portion thereof) is mirror-reflected away from the second surface 12b (i.e., with a return angle θ equal to the negative incident angle θ). R (Reflection), as indicated by reflector LB 117b. Reflector LB 117b returns toward LFC 102 and is folded by LFC 102 at the actual light folding angle α″. More precisely, reflector LB 117b is redirected by LFC 102 toward ICA 104, as indicated by second return LB 125b. Second return LB 125b is sensed by sensor 114.

[0112] Typically, due to manufacturing defects in Sample 10 and LFC 102, the second return LB 125b will not be parallel to the first return LB 125a. The angle δ between the first return LB 125a and the second return LB 125b—also known as the “angle deviation”—is equal to 2·θ. R And therefore depends on Δα′. This is shown from ray 105b1 (indicating...). Figure 1A One of the two incident rays LB 105b in the second incident ray) crosses clockwise to ray 125b1 (indicator) Figure 1A The angle δ of one of the two rays returning from LB 125b in the second ray, and therefore the angle δ in Figure 1A The middle is the correct position.

[0113] Also refer to Figure 1B , Figure 1B A schematic perspective view of sample 10 is shown during inspection of sample 10 by system 100. Figure 1BThe diagram also indicates the first incident LB 105a, the first return LB 133a, the folding LB 113b (which should be understood as nominally perpendicularly incident on the second surface 12b) and the reflection LB 117b.

[0114] Figure 1C A first point 133a and a second point 133b, respectively formed on the photosensitive surface 134 of sensor 114 by a first return LB 125a and a second return LB 125b, are schematically depicted according to some embodiments. u1 and u2 are the horizontal coordinates (i.e., measured along the x-axis) of the first point 133a and the second point 133b, respectively. (Assuming...) Figure 1C The coordinate system depicted in the middle and Figure 1A The coordinate system depicted in the figure is consistent with the possible translation of the origin. Therefore, Figure 1C The x-axis in the image extends parallel to the first surface 12a from the second incident LB105b to the first incident LB105a. The angle δ can be directly inferred from the difference Δu = u2 - u1. As a non-limiting example, when the measurement is based on an autocollimator (i.e., in an embodiment where ICA 104 is or includes an autocollimator), δ = Δu / f, such that Δα′ = -Δu / (2·f), where f is the focal length of the collimating lens of the autocollimator. (More precisely, Δα′ is equal to -Δu / (2·f), the accuracy of which depends on the uncertainty of the actual light folding angle α″ and any other relevant uncertainties of the parameters of LFC 102, ICA 104, and the orientation base structure 120).

[0115] According to some implementation methods, such as Figure 1C As depicted, due to misalignment of LFC 102 and sample 10, for example, in terms of their respective yaw angles (i.e., around the z-axis), the vertical coordinates (i.e., measured along the y-axis) of the first point 133a and the second point 133b may differ slightly from each other. Such potential misalignment can be minimized during the calibration of system 100 using, for example, an autocollimator.

[0116] Alternatively, according to some embodiments in which ICA104 is or includes an interferometric measuring device, the angle δ can be derived from the interference pattern formed by the first return LB 125a and the second return LB 125b. More specifically, in such an embodiment, the first return LB 125a constitutes a first return wavefront obtained from a first incident wavefront reflected away from the first surface 12a, and the second return LB 125b constitutes a second return wavefront obtained by folding the second incident wavefront by LFC 102, reflecting it away from the second surface 12b, and then folding it again by LFC 102. The return wavefronts are recombined, and the interference pattern of the return wavefronts is measured by sensor 114. If the first and second wavefronts are normally incident on their respective surfaces (i.e., the first surface 12a or the second surface 12b, respectively), the recombined wavefronts will form a uniform pattern on sensor 114. If the second surface 12b deviates from its nominal tilt, the recombined wavefronts will form a periodic pattern on sensor 114. The deviation Δα′ can be derived from the periodicity of the pattern.

[0117] According to some embodiments, controller 108 may be communicatively associated with computing module 130. Computing module 130 may include a processor and volatile and / or non-volatile memory components. The processor may be configured to receive sensor 114 data (i.e., the values ​​of u1 and u2) from controller 130 and calculate Δα′ based on the sensor 114 data. Optionally, according to some embodiments, the processor may also be configured to calculate the uncertainty of Δα′ (the calculated value) taking into account LFC 102 (including the uncertainty of the actual optical folding angle), ICA 104, and manufacturing tolerances and defects of directional infrastructure 120. According to some embodiments, computing module 130 may be included in system 100.

[0118] According to some implementations, system 100 may also include two shutters (and) Figure 2A and Figure 2B The blocking elements in the two shutters are similarly positioned, and the two shutters are configured to selectively block each of the first return LB 125a and the second return LB 125b, so that each of the return LBs 125 can be sensed individually (thus facilitating the attribution of each of the points 133 to the return LB that caused that point).

[0119] According to some embodiments, the first surface 12a and the second surface 12b may be coated or temporarily coated with a reflective coating such that light incident on the first surface 12a and the second surface 12b is reflected to the maximum extent or at least the reflection from thereis is increased. According to some embodiments, wherein the light source 112 is configured to generate multicolor light, the first surface 12a may be coated with a first coating configured to reflect light in a first spectrum, and the second surface 12b (or LFC 102) may be coated with a second coating configured to reflect light in a second spectrum that does not overlap with or substantially does not overlap with the first spectrum. In such embodiments, a spectral filter or spectral filter device (optionally, instead of a shutter) may be used to achieve selective blocking of the first return LB 125a and the second return LB 125b, the spectral filter or spectral filter device being positioned such that each of the return LBs 125 is incident thereon and configured to selectively block or at least partially block light in the second and first spectra, respectively.

[0120] According to some alternative implementations, a first (passive) spectral filter can be used to filter the first incident LB 105a into a first spectrum, and a second (passive) spectral filter can be used to filter the second incident LB 105b into a second spectrum. In such an implementation, in order to enable the individual sensing of each of the return LB 125s, an additional spectral filter can be used, which is positioned between the spectral filter and the sensor 114 and configured to selectively filter light from either the first or second spectrum passing through.

[0121] Note that a spectral filter or spectral filter device can be used to reduce the signal associated with stray light arriving at sensor 114, which is associated with any of the incident LB 105.

[0122] Despite Figure 1A In this disclosure, the first surface 12a and the second surface 12b are shown as sharing a common edge; however, it should be understood that the scope of this disclosure is not limited to the measurement of samples thus shaped. In particular, as described above, any sample including an external and flat first surface and an external and flat second surface that is inclined relative to the first surface but does not share a common edge with the first surface can also undergo measurement using system 100.

[0123] Figure 2A and Figure 2BAn optically based system 200, according to some embodiments, for verifying the perpendicularity of an external, flat surface of a sample relative to at least two other external, flat surfaces of the sample, wherein the at least two other external, flat surfaces are parallel to each other. System 200 corresponds to a specific embodiment of system 100. More specifically, Figure 2A A side view of a system 200 according to some embodiments and a sample 20 examined by the system 200 is provided. The sample 20 may be an optical element, such as a prism, waveguide, or beam splitter. According to some embodiments, the prism may be shaped as a polyhedron. According to some embodiments, such as... Figure 2A and Figure 2B The depicted cross-section of sample 20, taken parallel to the zx plane, can define a polygon.

[0124] Sample 20 includes an externally flat first surface 22a, an externally flat second surface 22b, and an externally flat third surface 22c. The first surface 22a and the third surface 22c are nominally parallel by design. Furthermore, sample 20 is manufactured to exhibit a nominal tilt angle of 90° between the first surface 22a and the second surface 22b. However, due to manufacturing defects, the actual tilt angle of the second surface 22b relative to the first surface 22a (in...) Figure 2A and Figure 2B The denoted χ′ is usually different from 90°.

[0125] Note that using existing manufacturing techniques, the (manufacturing) tolerance of the actual angle between surfaces manufactured as parallel is significantly smaller than the tolerance of the actual angle between surfaces manufactured as non-parallel. Therefore, since the first surface 22a and the third surface 22c are manufactured as parallel, the deviation in their parallelism is expected to be negligible compared to the deviation of the actual tilt angle χ′ from 90°. Therefore, the actual angle ψ′ (also called the "actual supplementary angle") between the second surface 22b and the third surface 22c can be taken as equal to 180° - χ′, i.e., the supplementary angle of the actual tilt angle χ′. (The nominal value of the actual supplementary angle ψ′ is 90°.)

[0126] System 200 includes LFC 202 and ICA 204. LFC 202 corresponds to a specific embodiment of LFC 102, and LFC 202 is configured to nominally fold light by 90°. According to some embodiments, LFC 202 is a prism, one or more mirrors, or a diffraction grating, and LFC 202 is nominally configured to fold light incident on the first surface 22a in a direction perpendicular to it by 90°. According to some embodiments, LFC 202 is a pentaprism or a prism with similar function (i.e., insensitive to pitch changes).

[0127] ICA 204 corresponds to a specific embodiment of ICA 104, and ICA 204 includes a light source (not shown), a sensor (not shown), and optionally optical devices (not shown), which correspond to specific embodiments of light source 112, sensor 114, and optical device 118, respectively. According to some embodiments, ICA 204 includes an autocollimator 240. The autocollimator 240 can be configured to generate a collimated LB 201. A first incident LB 205a and a second incident LB 205b form a sub-beam of LB 201. According to some embodiments, and as... Figure 2A and Figure 2B As depicted, the ICA204 may additionally include a pair of blocking elements 246a and 246b, thereby enabling selective blocking of each of the first incident LB 205a and the second incident LB 205b. According to some embodiments, each of the blocking elements 246a and 246b may be a shutter (e.g., controllable by the controller 208).

[0128] The first incident LB 205a is directed to sample 20, and the second incident LB 205b is directed to LFC 202. According to some embodiments, and as... Figure 2A As depicted, ICA 204 and sample 20 are positioned and oriented such that a first incident LB 205a is incident on a first surface 22a perpendicular to it. The first incident LB 205a (or at least a portion thereof) is reflected away from the first surface 22a as indicated by a first returned LB 225a. The first returned LB 225a is sensed by an autocollimator 240.

[0129] LFC 202 is configured to nominally fold the second incident LB 205b by 90°. More precisely, LFC 202 is configured to fold the second incident LB 205b such that the (first) fold LB 213b (obtained by folding the second incident LB 205b) is nominally oriented at 90° relative to the second incident LB 205b and (nominally) perpendicular to the second surface 12b. In practice, in embodiments of LFC 202 that are sensitive to pitch changes, the actual optical folding angle χ″ of LFC 202 may deviate slightly from 90° due to manufacturing defects and alignment inaccuracies. As detailed below, this is achieved by flipping the sample 20 to reverse the first surface 22a and the third surface 22c (while maintaining the nominal orientation of the second surface 22b relative to LFC 202), and repeating... Figure 2B The measurements described herein can eliminate or substantially eliminate the effects of manufacturing defects in LFC 202.

[0130] Folded LB 213b is incident on the second surface 22b at a first incident angle η1. The first incident angle η1 depends on the deviation Δχ′=90°-χ′ (i.e., the deviation of the tilt of the second surface 22b from the nominal tilt) and the deviation Δχ″=90°-χ″′ (i.e., the deviation of the actual light folding angle of LFC 202 from 90°). The normal of the second surface 22b is... Figure 2A The middle is indicated by the (straight) dashed line C1.

[0131] As indicated by the (first) reflector LB 217b, the folded LB 213b (or at least a portion thereof) is mirror-reflected away from the second surface 22b (i.e., with a return angle ζ1 equal to the negative first incident angle η1). The reflector LB 217b returns toward LFC 202 and is folded by LFC 202 at an actual light folding angle χ″, thereby producing the second return LB 225b. The second return LB 225b is sensed by sensor 214.

[0132] The angle δ1 (also known as the "first angle deviation") between the second return LB 225b and the first return LB 225a is equal to 2·ζ. Therefore, the angle δ1 depends on Δχ′. Figure 2C The diagram schematically depicts a first point 233a and a second point 233b formed on the photosensitive surface 234 of an autocollimator 240 by a first return LB225a and a second return LB225b, respectively, according to some embodiments. w1 and w2 are the horizontal coordinates (i.e., measured along the x-axis) of the first point 233a and the second point 233b, respectively. Angle δ1 can be directly deduced from the difference Δw = w2 - w1.

[0133] Reference Figure 2B ,and Figure 2A In contrast, sample 20 has been flipped so that the first surface 22a and the third surface 22c are reversed (while maintaining the nominal orientation of the second surface 22b relative to LFC 202).

[0134] The third incident LB 205a′ is directed toward the sample 20 in a manner perpendicular to the sample 20, and the fourth incident LB 205b′ is directed toward the LFC 202. As indicated by the third return LB 225a′, the third incident LB 205a′ (or at least a portion thereof) is reflected away from the third surface 22c. The third return LB 225b′ is sensed by the sensor 214.

[0135] The fourth incident LB 205b′ is incident on LFC 202, thus producing a second fold LB 213b′. The second fold LB 213b′ is incident on the second surface 22b at a second incident angle η2. The second incident angle η2 depends on the deviation Δψ′ = 90° - ψ′ (i.e., the deviation of the actual supplementary angle ψ′ from 90°) and the deviation Δχ″ = 90° - χ″. The normal to the second surface 22b is... Figure 2B The middle is indicated by the (straight) dashed line C2.

[0136] As indicated by the second reflection LB 217b′, the fourth incident LB 205b′ is (at least partially) specularly reflected away from the second surface 22b (i.e., reflected at a return angle ζ2 equal to the negative second incident angle η2). The second reflection LB 217b′ returns toward LFA 202 and is folded by LFA 202 at an actual light folding angle χ″, as indicated by the fourth return LB 225b′. The fourth return LB 225b′ is sensed by sensor 214.

[0137] The angle δ2 (also known as the "second angle deviation") between the fourth return LB 225b′ and the third return LB 225a′ is equal to 2·ζ2. Therefore, the angle δ2 depends on Δψ′, and thus on Δχ′ (since χ′+ψ′=180°, Δψ′=-Δχ′). Figure 2D The diagram schematically depicts a third point 233a' and a fourth point 233b' formed on the photosensitive surface 234 of sensor 214 by a third return LB 225a' and a fourth return LB 225b', respectively, according to some embodiments. w1' and w2' are the horizontal coordinates of the third point 233a' and the fourth point 233b', respectively. The angle δ2 can be directly deduced from the difference Δw' = w2' - w1'.

[0138] Despite Figure 2C and Figure 2D In the diagram, Δw and Δw′ are both shown as negative (making δ1 and δ2 negative), but it should be understood that Δw and Δw′ can usually have opposite signs (making δ1 and δ2 have opposite signs), or they can both be positive (making δ1 and δ2 positive).

[0139] Each of the measured angles δ1 and δ2 can be used to provide a corresponding estimate of the deviation angle Δχ′. In the absence of any defects in system 200, η2 will be equal to -η1 and δ1 will be equal to -δ2. However, in practice, these two estimates are often different because the actual optical folding angle deviates from its nominal value. Since both δ1 and δ2 have the same (when the LFC is insensitive to pitch changes) or substantially the same dependence on the actual optical folding angle χ″ (i.e., both δ1 and δ2 increase as χ″ increases and decrease as χ″ decreases), the deviation of the optical folding angle can be offset or substantially offset by averaging the two estimates of the deviation angle Δχ′. That is, <Δχ′> is equal to or substantially equal to -(δ1-δ2) / 4. In particular, in embodiments where ICA204 is or includes an autocollimator, <Δχ′> is equal to or substantially equal to -(Δw-Δw′) / (2·f0), where f0 is the focal length of the collimating lens of the autocollimator.

[0140] According to some embodiments, the first surface 22a, the second surface 22b, and the third surface 22c may be coated or temporarily coated with a reflective coating such that light incident thereon is reflected to the maximum extent or at least the reflection from there is increased. According to some embodiments, wherein the autocollimator 240 is configured to generate a multicolor LB, the first surface 12a and the third surface 12c may be coated with a first coating configured to reflect light in a first spectrum, and the second surface 12b may be coated with a second coating configured to reflect light in a second spectrum, different from the first spectrum. In such embodiments, the autocollimator 240 may include a spectral filter configured to selectively filter light in either the first or second spectrum passing therethrough, thereby facilitating the individual sensing of each of the returned LBs 225.

[0141] According to some embodiments, blocking elements 246a and 246b may be spectral filters (specifically, dichroic filters) configured to block light in the second and first spectra. In such embodiments, in order to individually sense each of the return LBs 225, an additional spectral filter may be employed, positioned between or included in the autocollimator 240, and configured to selectively filter light in the first or second spectrum passing therethrough.

[0142] Despite Figure 2A and Figure 2BIn the diagram, the second surface 22b is shown extending from the first surface 22a to the third surface 22c, but it should be understood that the scope of this disclosure is not limited to the measurement of such shaped samples. In particular, as described above, any sample that includes an externally flat first surface, an externally flat second surface inclined relative to the first surface, and an externally flat third surface parallel to the first surface, such that the second surface does not share a common edge with the first surface and / or does not share a common edge with the third surface, can also undergo measurement using system 200.

[0143] according to Figure 2A and Figure 2B In some alternative embodiments not depicted herein, the light source 212 and optical device 218 may be configured to generate an extended (collimated) laser beam or a pair of parallel and spaced (collimated) laser beams, substantially as described above in the description of system 100. According to other embodiments, ICA 204 may be or include an interferometric measuring device, as described above in the description of system 100.

[0144] Figure 3 An optically based system 300 for verifying the angle between two outer flat surfaces of a sample, according to some embodiments, is schematically depicted. System 300 corresponds to a specific embodiment of system 100, wherein the LFC is or includes a prism. More specifically, Figure 3 A side view of a system 300 according to some embodiments and a sample 10 examined by the system 300 is provided. The system 300 includes a prism 302, an ICA 304 (components not shown), and an orientation base structure 320. According to some embodiments, and as... Figure 3 The system 300 depicted also includes a controller 308 and optionally a computing module 330. The prism 302, ICA 304, directional infrastructure 320, controller 308, and computing module 330 correspond to specific embodiments of LFC 102, ICA 104, directional infrastructure 120, controller 108, and computing module 130, respectively.

[0145] According to some embodiments, the prism 302 is insensitive to changes in the pitch angle (i.e., rotation about the y-axis) at least within a continuous range of pitch angles. According to some such embodiments, and as... Figure 3 The prism 302 depicted may be a pentaprism or a prism with similar functionality, such as a prism comprising an even number of internal reflecting surfaces. According to Figure 3In some alternative embodiments not shown, instead of prism 322, system 300 may include two mirrors set at the same angle relative to each other, with the two surfaces (pentagonal prism first surface 328a and pentaprism second surface 328b) of prism 302 set at the same angle to reflect the transmissive portion of the second incident LB 305b internally.

[0146] Figure 3 The diagram illustrates a first incident LB 305a, a first returning LB 325a, a second incident LB 305b, a folded LB 313b, a reflected LB 317b, and a second returning LB 325b, which correspond to specific embodiments of the first incident LB 105a, the first returning LB 125a, the second incident LB 105b, the folded LB 113b, the reflected LB 117b, and the second returning LB 125b, respectively. The trajectories of the second incident LB 305b and the reflected LB 317b within the prism 302 after entering it are also shown. The penetrating portions of the second incident LB 305b are designated 309b1, 309b2, and 309b3 after entering the prism 302, after reflection within the prism 302, and after two reflections within the prism 302, respectively. The penetrating portions of reflective LB 317b are numbered 321b1, 321b2, and 321b3 after being refracted into prism 302, reflected in prism 302, and reflected twice in prism 302, respectively.

[0147] The angle of incidence of folded LB 313b on the second surface 12b is marked as θ3. The angular deviation between the second return LB 325b and the first return LB 325a is marked as δ3.

[0148] Figure 4 An optically based system 400 for verifying the angle between two outer flat surfaces of a sample, according to some embodiments, is schematically depicted. System 400 corresponds to a specific embodiment of system 100, wherein the LFC is or includes a mirror. More specifically, Figure 4 A side view of a system 400 according to some embodiments and a sample 10 examined by the system 400 is provided. The system 400 includes a mirror 402, an ICA 404 (components not shown), and an orientation base structure 420. According to some embodiments, and as... Figure 4 The system 400, as depicted, also includes a controller 408 and optionally a computing module 430. Mirror 402, ICA 404, directional infrastructure 420, controller 408, and computing module 430 correspond to specific embodiments of LFC 102, ICA 104, directional infrastructure 120, controller 108, and computing module 130, respectively.

[0149] According to some implementation methods, and as Figure 4The mirror 402 described can be a plane mirror.

[0150] Figure 4 The diagram indicates a first incident LB 405a, a first return LB 425a, a second incident LB 405b, a folding LB 413b, a reflecting LB 417b, and a second return LB 425b, which correspond to specific embodiments of the first incident LB 105a, the first return LB 125a, the second incident LB 105b, the folding LB 113b, the reflecting LB 117b, and the second return LB 125b, respectively.

[0151] The angle of incidence of folded LB 413b on the second surface 12b is marked as θ4. The angular deviation between the second return LB 425b and the first return LB 425a is marked as δ4.

[0152] method

[0153] According to some aspects of the embodiments, an optical-based method is provided for measuring the external flat surface of a sample. This method can be used to verify the orientation of one external and flat surface of a sample relative to another external and flat surface of the sample. Figure 5 A flowchart of such a method (optics-based method 500) according to some embodiments is presented. Method 500 may include:

[0154] - Optional stage 505, in which the system (e.g., system 100) used to implement the method is calibrated.

[0155] - Stage 510, in which a sample to be tested (e.g., sample 10) is provided. The sample includes: an externally flat first surface (e.g., first surface 12a) and an externally flat second surface (e.g., second surface 12b), the second surface being nominally tilted relative to the first surface at a nominal tilt angle (e.g., nominal tilt angle α).

[0156] - Stage 520, wherein (e.g., by means of light source 112 and optical device 118) a first incident LB (e.g., first incident LB 105a) and a second incident LB (e.g., second incident LB 105b) parallel to the first incident LB are generated and directed to the first surface.

[0157] - Stage 530, wherein the first returning LB (e.g., first returning LB 125a) is obtained by reflecting the first incident LB away from the first surface.

[0158] - Stage 540, wherein a second returning LB (e.g., second returning LB 125b) is obtained by nominally folding the second incident LB at a light folding angle equal to the nominal tilt angle, reflecting the folded LB (e.g., folded LB 113b) away from the second surface, and nominally folding the reflecting LB (e.g., reflecting LB 117b) at a light folding angle.

[0159] - Stage 550, in which the angular deviation of the second return LB relative to the first return LB is measured (e.g., using sensor 114 or autocollimator 240).

[0160] - Stage 560, wherein the actual tilt angle of the second surface relative to the first surface is derived at least based on the measured angular deviation.

[0161] As used herein, the term "obtain" can be used in both active and passive senses. Thus, for example, in stage 540, the first return LB may be obtained not due to any operation performed in stage 540, but due to the generation of the first incident LB in stage 520. Generally, a stage can describe the result or effect of an active operation performed by a user or by a system for implementing the method, and / or one or more operations performed in one or more earlier stages.

[0162] Method 500 can be implemented using an optical-based system (e.g., any of optical-based systems 100, 300, and 400, or similar optical-based systems), as described above in their respective descriptions. In particular, according to some embodiments, method 500 can be based on an automatic collimator, on a measurement of the distance between laser beams, or on interferometry, as detailed in the descriptions of various embodiments of system 100. In stage 540, a folded LB can be obtained from the second incident LB using any of LFC 102, prism 302, and mirror 402, or similar functional LFCs. Similarly, a second returned LB can be obtained from the reflected LB using any of LFC 102, prism 302, and mirror 402, or similar functional LFCs.

[0163] According to some embodiments, in stage 520, the first incident LB can be projected onto the first surface normally (i.e., perpendicularly) with respect to the first surface. Therefore, in such an embodiment, the folded LB (obtained by folding the second incident LB) will be nominally normally incident on the second surface. According to some embodiments, in stage 505, a "gold standard" (GS) sample can be used as part of the calibration of the system for implementing method 500. More specifically, given a sample to be tested, a corresponding GS sample (i.e., a sample known to exhibit the geometry required for high accuracy) can be used in the calibration of the system. In particular, the GS sample can be used to align the orientable stage (e.g., stage 122) and LFC on which the sample is mounted, such that the folded LB is perpendicularly incident (with the accuracy provided by the GS sample) on the second surface of the GS sample (similar to second surface 12b). The GS sample can also be used to orient the stage such that the first incident LB is perpendicularly incident on the first surface of the GS sample (similar to first surface 12a). An automatic collimator, whether it is part of the system's ICA (e.g., ICA104) or not included in the system, can be used to perform alignment and verify the perpendicularity of the first incident LB.

[0164] According to some implementations, once the sample to be tested has been provided and arranged on, for example, an orientable stage, calibration or additional calibration can be performed after stage 510. Additional calibration may include, for example, an orienting or redirection stage (e.g., using an autocollimator) such that the first incident LB is incident perpendicularly on the first surface (of the sample to be tested).

[0165] According to some embodiments, in stage 520, an automatic collimator (e.g., automatic collimator 240) can be used to generate a single incident LB, wherein the first incident LB and the second incident LB constitute a sub-beam. Alternatively, an extended (collimated) laser beam can be generated, wherein the first incident LB and the second incident LB constitute a sub-beam. According to some other embodiments, a pair of parallel and spaced-apart laser beams, respectively corresponding to the first incident LB and the second incident LB, can be generated.

[0166] According to some embodiments, in stages 530 and 540, an autocollimator (e.g., autocollimator 240, and more generally, the same autocollimator used in embodiments where an autocollimator is used to prepare the incident LB) can be employed to sense the returned LB. According to some embodiments, a shutter and / or spectral filter can be employed to selectively block or partially block the first or second returned LB, essentially as described above. Figure 1A and Figure 2A and Figure 2BAs described in the description. In addition to helping to attribute each of a pair of points (on the photosensitive surface of the optical sensor or image sensor (e.g., sensor 114) used to sense the return LB) to the return LB of the formed point, blocking one return LB and simultaneously sensing the other return LB can be used to improve measurement accuracy by attenuating the signal associated with stray light.

[0167] According to some embodiments, particularly those employing an automatic collimator (e.g., automatic collimator 240) to implement stages 520, 530, and 540, in stage 550, via Calculate the angular deviation of the second return LB relative to the first return LB. and These are the horizontal coordinates of the first point and the second point (e.g., the first point 133a and the second point 133b) formed by the first return LB and the second return LB on the photosensitive surface (e.g., photosensitive surface 134) of the automatic collimator. It is the focal length of the collimating lens in an automatic collimator.

[0168] In phase 560, it can be done through relationships From angular deviation (value) obtains the actual tilt angle value in It is the nominal tilt angle of the second surface relative to the first surface (according to the...) Figures 1A to 4 The definition of angle used in the description is based on clockwise increments. More generally, It can be equal to approximately For example It is possible and Between, in and Between, or even in and Between. Each possibility corresponds to a separate implementation. According to some implementations, the uncertainty of the actual tilt angle can also be calculated in stage 560, at least based on the manufacturing tolerances and defects of the ICA configured to generate the incident LB and measure the angular deviation between the returned LB. According to some implementations, the folding angle can also be considered additionally. The uncertainty of the tilt angle is calculated using the uncertainty of the tilt angle.

[0169] Figure 6A flowchart of an optically based method 600 for measuring the external flatness of a sample, according to some embodiments, is presented. Method 600 corresponds to a specific embodiment of method 500 and can be used to verify the perpendicularity of an external and flat surface of a sample relative to at least two other external and flat surfaces of the sample, wherein the at least two other external and flat surfaces are parallel to each other. Method 600 may include:

[0170] - Stage 605, in which a sample to be tested (e.g., sample 20) is provided. The sample includes an externally flat first surface (e.g., first surface 22a), an externally flat second surface (e.g., second surface 22b) that is nominally inclined relative to the first surface at a nominal tilt angle, and an externally flat third surface (e.g., third surface 22c) that is parallel to the first surface.

[0171] - Stage 610, wherein (e.g. by an automatic collimator 240) a first incident LB (e.g., first incident LB 205a) and a second incident LB (e.g., second incident LB 205b) parallel to the first incident LB are generated and guided normally to the first surface.

[0172] - Stage 615, wherein a first returning LB (e.g., first returning LB 225a) is obtained by reflecting the first incident LB away from the first surface.

[0173] - Stage 620, wherein a second returning LB (e.g., second returning LB 225b) is obtained by nominally folding the second incident LB with a light folding angle equal to the nominal tilt angle, reflecting the folded LB (e.g., first folded LB 213b) away from the second surface, and nominally folding the reflecting LB (e.g., first reflecting LB 217b) with a light folding angle.

[0174] - Stage 625, in which the first angular deviation of the second return LB relative to the first return LB is measured.

[0175] - Stage 630, in which the sample is flipped so that the first and third surfaces are reversed while the nominal orientation of the second surface is maintained.

[0176] - Stage 635, wherein (e.g., by means of an automatic collimator 240) a third incident LB (e.g., third incident LB 205a′) is generated and normally guided to the third surface, and a fourth incident LB (e.g., fourth incident LB 205b′) is parallel to the third incident LB.

[0177] - Stage 640, wherein a third return LB (e.g., third return LB 225a′) is obtained by reflecting the third incident LB away from the third surface.

[0178] - Stage 645, wherein a fourth returning LB (e.g., fourth returning LB 225b') is obtained by nominally folding the fourth incident LB with an optical folding angle, reflecting the folded LB (e.g., second folded LB 213b') away from the second surface, and nominally folding the reflecting LB (e.g., second reflecting LB 217b') with an optical folding angle.

[0179] - Stage 650, measure the second angle deviation between the fourth return LB and the third return LB.

[0180] - Stage 655, wherein the actual tilt angle of the second surface relative to the first surface is derived based on the measured first angular deviation and second angular deviation.

[0181] Method 600 can be implemented using an optical-based system (e.g., optical-based system 200 or a similar optical-based system), as described above. Figures 2A to 2D As described in the description. In particular, according to some embodiments, method 600 may be based on an automatic collimator, based on a measurement of the distance between laser beams, or based on interferometry. In stage 620, a first folded LB and a second returned LB may be obtained from the second incident LB and the first reflected LB, respectively, using LFC 202 or an LFC with similar functionality. The LFC may be or include a prism (e.g., a pentaprism), a mirror, or a diffraction grating, and the LFC is nominally configured to fold light incident on the first surface 22a at a direction perpendicular to it by 90°. Similarly, in stage 645, a second folded LB and a fourth returned LB may be obtained from the fourth incident LB and the second reflected LB, respectively, using LFC 202 or an LFC with similar functionality.

[0182] According to some implementations, method 600 may include an optional calibration phase similar to phase 505 of method 500. Figure 6 (Not shown in the image).

[0183] According to some embodiments, in stages 610 and 635, an autocollimator (e.g., an autocollimator) can be used to generate a pair of parallel incident LBs. According to some embodiments, in stages 615, 620, 640, and 645, an autocollimator (e.g., an autocollimator for preparing the incident LBs) can be used to sense the returned LBs. According to some embodiments, a shutter and / or spectral filter can be used to selectively block or partially block one of the second and first returned LBs, and one of the fourth and third returned LBs, substantially as described above. Figure 2A and Figure 2B As described in the description.

[0184] According to some embodiments, particularly those employing an automatic collimator (e.g., automatic collimator 240) to implement stages 610, 615, 620, 635, 640, and 645, in stage 625, via The obtained first angular deviation of the second return LB relative to the first return LB and The first point and the second point (e.g., the first point 233a and the second point 233b) are formed on the photosensitive surface (e.g., photosensitive surface 234) of the automatic collimator by the first return LB and the second return LB, respectively. This is the focal length of the collimating lens in the automatic collimator. Similarly, in stage 650, via... Obtain the second angular deviation of the fourth return LB relative to the third return LB. and These are the horizontal coordinates of the third and fourth points (e.g., third point 233a′ and fourth point 233b′) formed on the photosensitive surface of the automatic collimator by the third return LB and the fourth return LB, respectively.

[0185] In stage 655, it can be done through relationships From angular deviation and (value) obtains the actual tilt angle value More generally, It can be equal to approximately For example exist and Between, in and Between, or even in and Between. Each possibility corresponds to a separate implementation. According to some implementations, in stage 655, the uncertainty of the actual tilt angle can also be calculated, at least based on the manufacturing tolerances and defects of the ICA configured to generate the incident LB and measure the angular deviation between the returned LB.

[0186] It should be understood that, for clarity, certain features of this disclosure described in the context of a single implementation may also be provided in combination in a single implementation. Conversely, for brevity, various features of this disclosure described in the context of a single implementation may also be provided individually or in any suitable sub-combination or suitably provided in any other described implementation of this disclosure. Unless expressly specified therein, features described in the context of an implementation should not be considered essential features of that implementation.

[0187] Although the stages of a method according to some embodiments may be described in a particular order, the method of this disclosure may include some or all of the stages performed in a different order. The method of this disclosure may include some or all of the described stages. Unless expressly specified as such, no particular stage in the disclosed method should be considered a necessary stage of the method.

[0188] Although this disclosure has been described in conjunction with specific embodiments thereof, it will be apparent that many alternatives, modifications, and variations are possible and will be obvious to those skilled in the art. Therefore, this disclosure covers all such alternatives, modifications, and variations that fall within the scope of the appended claims. It should be understood that the application of this disclosure is not necessarily limited to the details of the construction and arrangement of the components and / or methods set forth herein. Other embodiments may be implemented, and embodiments may be implemented in various ways.

[0189] The wording and terminology used herein are for descriptive purposes and should not be construed as restrictive. Any references or designations used in this application should not be interpreted as an admission that such references are prior art to this disclosure. Section headings used herein are for ease of understanding and should not be construed as necessarily limiting.

Claims

1. An optical-based method for verifying the angle between the outer flat surfaces of a sample, the method comprising: A sample is provided, the sample comprising an externally flat first surface and an externally flat second surface, the second surface being nominally inclined relative to the first surface at a nominal tilt angle; A first incident beam is generated and directed to the first surface, and a second incident beam is generated parallel to the first incident beam. A first returning beam is obtained by reflecting the first incident beam away from the first surface; A second returning beam is obtained by folding the second incident beam at a light folding angle nominally equal to the nominal tilt angle, reflecting the folded beam away from the second surface, and folding the reflected beam at the light folding angle. Measure the first angular deviation of the second returning beam relative to the first returning beam; as well as The actual tilt angle of the second surface relative to the first surface is derived, at least based on the measured first angular deviation, wherein... The nominal tilt angle is 90°, and the sample includes an outer flat third surface parallel to the first surface, wherein the first incident beam is guided to the first surface in a manner perpendicular to the first surface, and wherein the method further includes, after measuring the first angular deviation: The sample is flipped so that the first and third surfaces are reversed, while the second surface is kept in the nominal orientation relative to the light folding component LFC used to achieve folding; A third incident beam and a fourth incident beam parallel to the third incident beam are prepared, the third incident beam being guided to the third surface in a manner normal to the third surface; A third returning beam is obtained by reflecting the third incident beam away from the third surface; A fourth return beam is obtained by folding the fourth incident beam at a light folding angle nominally equal to the nominal tilt angle, reflecting the folded fourth incident beam away from the second surface, and folding the reflected fourth incident beam at the light folding angle. The second angular deviation of the fourth returning beam relative to the third returning beam is measured, and In deriving the actual tilt angle, the measured second angle deviation is also considered.

2. The optical-based method according to claim 1, wherein, The light folding component LFC is or includes a prism, one or more mirrors and / or a diffraction grating.

3. The optical-based method according to claim 2, wherein, The optical folding angle is insensitive to pitch changes in the optical folding component LFC.

4. The optical-based method according to claim 3, wherein, The light folding component LFC is or includes a prism that is insensitive to pitch changes, or a pair of mirrors or mirror devices that are angled relative to each other and are insensitive to pitch changes.

5. The optical-based method according to claim 4, wherein, The prism that is insensitive to pitch changes is a pentaprism.

6. The optical-based method according to any one of claims 1 to 2, wherein, The sample is or includes glass, polymer, metal and / or combinations thereof.

7. The optical-based method according to any one of claims 1 to 2, wherein, The sample is or includes glass, metal, crystal and / or a combination thereof.

8. The optical-based method according to claim 1, wherein, The sample is a prism or waveguide.

9. The optical-based method according to claim 1, wherein, The second surface does not share a common edge with the first surface.

10. The optical-based method according to claim 1, wherein, The first incident beam and the second incident beam are complementary portions of a single collimated beam.

11. The optical-based method according to claim 1, wherein, The first incident beam and the second incident beam are prepared by blocking one or more portions of a single collimated beam.

12. The optical-based method according to claim 10, wherein, The single collimated beam is multicolored.

13. The optical-based method according to claim 11, wherein, The single collimated beam is a laser beam.

14. The optical-based method according to claim 1, wherein, The first angular deviation was measured using an automatic collimator.

15. The optical-based method according to claim 14, wherein, The first angular deviation between the measured return beams is equal to or approximately equal to Δu / f, where Δu is the difference between the coordinates of the first point and the corresponding coordinates of the second point on the photosensitive surface of the autocollimator, f is the focal length of the collimating lens of the autocollimator, and wherein the first point is formed by the first return beam and the second point is formed by the second return beam.

16. The optical-based method of claim 1 further includes an initial calibration phase in which the system is calibrated using a sample as a gold standard.

17. The optical-based method according to claim 1, wherein, The uncertainty of the parallelism between the first surface and the third surface is less than the required measurement accuracy of the actual tilt angle.

18. The optical-based method of claim 1, further comprising, in the case that the sample includes an externally flat fourth surface nominally parallel to the second surface, suppressing internal reflections from the fourth surface.

19. An optical-based system for verifying the angle between the outer flat surfaces of a sample, the system comprising: A light folding component (LFC) is nominally configured to fold light incident on the light folding component (LFC) at a nominal tilt angle defined by an outer flat first surface and an outer flat second surface of the sample. ICA lighting and data acquisition device, including: A light generating component configured to (a) project a first incident light beam onto a first surface to generate a first returning light beam by reflection from the first surface, and (b) project a second incident light beam parallel to the first incident light beam onto the light folding member LFC to generate a second returning light beam by folding by the light folding member LFC, reflection from the second surface, and re-passing through the light folding member LFC; and At least one sensor configured to measure a first angular deviation of the second returned beam relative to the first returned beam, and / or an eyepiece assembly configured to enable manual measurement of the first angular deviation, wherein the measured first angular deviation indicates the actual tilt angle of the second surface relative to the first surface; and A calculation module, configured to calculate the actual tilt angle of the second surface relative to the first surface based at least on a measured first angular deviation, wherein... The nominal tilt angle is 90°, and the sample further includes an external flat third surface parallel to the first surface. The calculation module is also configured to calculate the actual tilt angle by additionally considering a second angular deviation of the measured fourth return beam relative to the third return beam, the third and fourth return beams being obtained in the following manner: When the sample is flipped so that the first surface and the third surface are reversed, (a') a third incident beam is projected onto the third surface of the sample to generate the third return beam through reflection from the third surface, and (b') a fourth incident beam parallel to the third incident beam is projected onto the light folding member LFC to generate the fourth return beam through folding of the fourth incident beam by the light folding member LFC, reflection from the second surface, and re-passing through the light folding member LFC.

20. The optical-based system of claim 19, configured such that the first incident beam is normally incident on the first surface.

21. The optical-based system according to claim 20, wherein, The system further includes an orientation base structure configured to orient the sample such that the first incident beam is normally incident on the first surface, and / or such that a folded beam obtained by folding the second incident beam by the light folding member LFC is nominally normally incident on the second surface.

22. The optical-based system according to claim 19, wherein, The illumination and acquisition device ICA is or includes an automatic collimator, which includes a light source and the at least one sensor.

23. The optical-based system according to claim 22, wherein, The illumination and acquisition device ICA also includes a pair of blocking elements configured to selectively block each of the first incident beam and the second incident beam.

24. The optical-based system according to claim 19, wherein, The light folding component LFC includes a prism, a plane mirror, and / or a diffraction grating.

25. The optical-based system according to claim 19, wherein, The light folding angle of the light folding component LFC is not sensitive to the pitch change of the light folding component LFC.

26. The optical-based system according to claim 25, wherein, The light folding component LFC is a prism that is insensitive to pitch changes, or a pair of mirrors or mirror devices that are angled relative to each other and are insensitive to pitch changes.

27. The optical-based system according to claim 26, wherein, The prism is a pentaprism.

28. The optical-based system according to claim 19, wherein, The light generating component includes a light source and an optical device, wherein the light source is configured to generate a single beam of light, and wherein the optical device is configured to collimate the single beam of light.

29. The optical-based system according to claim 28, wherein, The first incident beam and the second incident beam are complementary parts of the collimated beam.

30. The optical-based system according to claim 28, wherein, The light source is a multi-color light source.

31. The optical-based system according to claim 28, wherein, The light source is configured to generate a laser beam.

32. The optical-based system according to claim 19, wherein, The at least one sensor includes a light sensor and / or an image sensor.

33. The optical-based system according to claim 19, wherein, The calculation module is also configured to calculate the uncertainty in the calculated value of the actual tilt angle, taking into account at least the manufacturing tolerances and defects of the light folding component LFC and the illumination and acquisition device ICA.

34. The optical-based system according to claim 33 further includes an directional foundation structure, wherein, The calculation module is configured to additionally consider manufacturing tolerances and defects of the directional foundation structure when calculating the uncertainty in the calculated value of the actual tilt angle.

35. A method for manufacturing a sample having a pair of external flat surfaces disposed relative to each other at a nominal angle, the method comprising the following stages: Provide the original sample; The original sample is processed to obtain a processed sample, the processed sample comprising an outer flat first surface and an outer flat second surface, the second surface being set at a test angle relative to the first surface; The test angle is measured using an optical-based method according to any one of claims 1 to 18; If the difference between the test angle and the nominal angle is greater than a predefined difference, the processed sample is subjected to further processing to obtain a reprocessed sample. as well as The measurement phase is repeated, and if the difference between the test angle and the nominal angle is greater than the predefined difference, the reprocessing phase is repeated until the difference between the test angle and the nominal angle of the reprocessed sample is less than the predefined difference.

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