Optical verification of surface orientation

Abstract

This provides a simple, easily implementable measurement technology that avoids the use of high-end optical components, thereby meeting the demands of mass production. [Solution] The method includes (i) a sample comprising an outer flat first surface 22a and an outer flat second surface 22b nominally inclined upward at a nominal angle with respect to the first surface 22a, (ii) generating a second incident LB 205b parallel to a first incident light beam (LB) 205a, (iii) obtaining a first return LB 225a, (iv) obtaining a second return LB 225b by bending the second incident LB 205b at a nominal angle, reflecting the bent LB from the second surface 22b, and bending the reflected LB at a nominal angle, and (v) estimating the actual inclination angle between the first surface 22a and the second surface 22b based on measuring a first angular deviation between those return LBs.

Description

Technical Field

[0001] The present disclosure generally relates to methods and systems for surface measurement of a sample.

Background Art

[0002] Optical elements such as glass prisms are increasingly required to exhibit a higher tolerance for the angle between their surfaces. To meet the required angle tolerance, high-precision measurement for verifying the angle between the surfaces is necessary, which requires the use of high-end optical components and complex alignment and calibration procedures. Therefore, there is an unmet need in the art for simple and easily implementable measurement techniques that avoid the use of high-end optical components and thereby meet the demands of mass production.

Summary of the Invention

[0003] Aspects of the present disclosure relate, according to some embodiments thereof, to methods and systems for surface measurement of a sample. More specifically, but not exclusively, according to some embodiments of the present disclosure, aspects of the present disclosure relate to optical methods and systems for measurement of the outer surface of a sample.

[0004] This application discloses a fast, simple, and accurate method and system for measuring the inclination of an outer flat surface of a sample with respect to one or more other outer flat surfaces of the sample. To achieve this, two parallel-prepared light beams (LBs) can be used. A first LB strikes a first outer flat surface of the sample. A second LB is redirected to nominally strike a second outer flat surface of the sample, and its inclination angle with respect to the first surface is verified at the same angle of incidence as the first LB. Then, after the second reflected LB is redirected again, the angular deviation between the reflected LBs is measured. Advantageously, according to some embodiments of the art disclosed, a collimated light source, an optical sensor (or image sensor), an optical bending component for redirecting the second LB, and an orientation infrastructure for orienting the sample are sufficient to verify the inclination of the outer flat surface.

[0005] Therefore, according to some embodiments, an optical method is provided for verifying the angle between the flat outer surfaces of a sample. The method includes: - To provide a sample comprising an outer flat first surface and an outer flat second surface that is nominally inclined (intended to be inclined by design and fabrication) at a nominal inclination angle with respect to the first surface. - To generate a first incident light beam (LB) directed to a first surface, and a second incident LB parallel to the first incident LB. - Obtain the first return LB due to the reflection of the first incident LB from the first surface. - The second incident LB is bent at an optical refraction angle nominally equal to the nominal inclination angle, the bent LB is reflected from the second surface, and the reflected LB is bent at the optical refraction angle to obtain the second return LB. - Measure the first angular deviation of the second return LB relative to the first return LB. - To estimate the actual inclination angle of the second surface relative to the first surface, based at least on the measured first angular deviation.

[0006] According to some embodiments of the method, the estimated actual tilt angle is equal to or approximately equal to α+δ / 2 (for example, the estimated actual tilt angle is α+0.475·δ to α+0.525·δ, α+0.45·δ to α+0.55·δ, or even α+0.4·δ to α+0.6·δ, each possibility corresponding to a separate embodiment), where α is the nominal tilt angle and δ is the measured value of the first angular deviation.

[0007] According to some embodiments of the method, the first incident LB is directed perpendicular to the first surface and onto the first surface.

[0008] According to some embodiments of the method, bending is performed using an optical bending component (LFC), which is a prism, one or more mirrors, and / or a diffraction grating, or includes them.

[0009] According to some embodiments of the method, the optical bending angle is not affected by variations in the LFC pitch.

[0010] According to some embodiments of the method, the LFC is a pentaprism or a prism of a similar function, or a pair of mirrors set at a certain angle to each other, or a mirror device of a similar function, or includes them.

[0011] According to some embodiments of the method, the sample is glass, polymer, metal, crystal, and / or a combination thereof, or includes them.

[0012] According to some embodiments of the method, the sample is a prism.

[0013] According to some embodiments of the method, the second surface does not share a common edge with the first surface.

[0014] According to some embodiments of the method, the first incident LB and the second incident LB are complementary parts of a single collimated LB.

[0015] According to some embodiments of the method, the first incident LB and the second incident LB are prepared by blocking one or more portions of a single collimated LB.

[0016] According to some embodiments of the method, a single collimated LB is pleochroic.

[0017] According to some embodiments of the method, the single collimated LB is a laser beam.

[0018] According to some embodiments of the method, the first angular deviation is measured using an autocollimator.

[0019] According to one embodiment of the method, the first angular deviation between the return LBs is equal to or approximately equal to Δu / f, where Δu is the difference between the coordinates of the first spot and the corresponding coordinates of the second spot on the photosensitive surface of the autocollimator, and f is the focal length of the collimating lens of the autocollimator. The first spot is formed by the first return LB, and the second spot is formed by the second return LB.

[0020] According to some embodiments of the method, the method further includes an initial calibration step in which an absolute reference sample is used to calibrate the system.

[0021] According to some embodiments of the method, the nominal inclination angle is obtuse.

[0022] According to some embodiments of the method, the nominal inclination angle is acute.

[0023] According to some embodiments of the method, the nominal inclination angle is 90°, and the sample has an outer flat third surface parallel to the first surface, and the method further includes the following, following the measurement of a first angular deviation: - Invert the sample to reverse the first and third surfaces while maintaining the nominal orientation of the second surface relative to the LFC. -Preparing a third incident LB directed to the third surface and a fourth incident LB directed parallel to the third incident LB. -Obtaining a third return LB by reflection of the third incident LB from the third surface. -Bending the fourth incident LB at an optical bending angle nominally equal to the nominal tilt angle, reflecting the bent fourth incident LB from the second surface, and bending the fourth incident LB reflected at the optical bending angle to obtain a fourth return LB. -Measuring a second angular deviation of the fourth return LB with respect to the third return LB.

[0024] In the estimation of the actual tilt angle, the actual tilt angle is estimated by additionally considering the measured second angular deviation.

[0025] According to some embodiments of the method, the uncertainty in the parallelism between the first surface and the third surface is less than the required measurement accuracy of the actual tilt angle.

[0026] According to some embodiments of the method, the estimated actual tilt angle is equal to x+(δ1 - δ2) / 4 or approximately equal to %+(δ1 - δ2) / 4 (for example, the estimated actual tilt angle is %+0.235·(δ1 - δ2)~%+0.265·(δ1 - δ2), %+0.225·(δ1 - δ2)~%+0.275·(δ1 - δ2), or even %+0.2·(δ1 - δ2)~%+0.3·(δ1 - δ2), and each possibility corresponds to a separate embodiment). x is the nominal tilt angle. δ1 is the measured first angular deviation, and δ2 is the measured second angular deviation.

[0027] According to some embodiments of the method, the method further includes suppressing internal reflection from the fourth surface, provided that the sample includes an outer flat fourth surface that is nominally parallel to the second surface.

[0028] According to aspects of some embodiments, an optical system is provided for verifying the angle between the outer flat surfaces of a sample. The system includes the following. - An optically bending component (LFC) nominally configured to bend incident light at the top, at a nominal inclination angle defined by the outer flat first surface and the outer flat second surface of the sample. - Including the following: Lighting and collection equipment (ICA): ■ A photogenerating assembly for (a) projecting a first incident light beam (LB) onto a first surface to generate a first return LB by reflection from a first surface, and (b) projecting a second incident LB onto an LFC parallel to the first incident LB to generate a second return LB by reflection from a second surface and backflow through the LFC. ■ 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 allow manual measurement of the first angular deviation.

[0029] The measured first angular deviation indicates the actual inclination angle of the second surface relative to the first surface.

[0030] According to some embodiments of the system, the photogenerating assembly includes a light source and optical equipment.

[0031] According to some embodiments of the system, the system further includes an orientation infrastructure configured to orient a sample such that a first incident LB strikes the first surface perpendicularly (i.e., vertically) and / or that a bent LB obtained by the bending of a second incident LB by the LFC strikes the second surface nominally perpendicularly.

[0032] According to some embodiments of the system, the system comprises at least one sensor, and further comprises a computing module configured to calculate the actual inclination angle of a second surface relative to a first surface based on at least a measured first angular deviation.

[0033] According to some embodiments of the system, the system includes at least one sensor, and the ICA is an autocollimator or includes an autocollimator. The autocollimator includes a light source and at least one sensor.

[0034] According to some embodiments of the system, the ICA further includes a pair of blocking elements configured to allow selective blocking of each of the first and second incident beams. According to some such embodiments, the blocking element is a shutter that completely blocks the light beam incident on its top.

[0035] According to some embodiments of the system, the LFC includes a prism, one or more mirrors, and / or a diffraction grating.

[0036] According to some embodiments of the system, the optical bending angle of the LFC is not affected by variations in the LFC's pitch.

[0037] According to some embodiments of the system, the LFC is a pentaprism or a prism having a similar function, or a pair of mirrors positioned at a certain angle to each other, or a mirror device having a similar function, or includes them.

[0038] According to some embodiments of the system, the system is configured to facilitate the inversion of the sample.

[0039] 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 further includes an outer, flat third surface parallel to the first surface. The computing module is configured to calculate the actual tilt angle, taking into additional consideration the measured second angular deviation of the fourth return LB relative to the third return LB. When the sample is inverted, 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 light beam onto the third surface of the sample so as to produce the third return LB by reflection from the third surface, and (b') the fourth return LB is obtained by projecting a fourth incident LB onto the LFC parallel to the third incident LB so as to produce the fourth return LB by reflection from the LFC, the second surface, and its bending due to reverse reflection through the LFC.

[0040] According to some embodiments of the system, the calculation module is further configured to calculate the uncertainty in the acquired value of the actual tilt angle, taking into account at least the manufacturing tolerances and imperfections of the LFC and ICA.

[0041] According to some embodiments of the system, the system includes an orientation infrastructure, and the calculation module is configured to calculate the uncertainty in the calculated value of the actual tilt angle, taking into additional consideration the manufacturing tolerances and imperfections of the orientation infrastructure.

[0042] According to some embodiments of the system, the photogenerating assembly includes a light source and an optical instrument. The light source is configured to generate a single LB. The optical instrument is configured to collimate the single LB.

[0043] According to some embodiments of the system, the first incident LB and the second incident LB are complementary portions of the collimated LB.

[0044] According to some embodiments of the system, the light source is a polychromatic light source.

[0045] According to some embodiments of the system, the light source is a monochromatic light source.

[0046] According to some embodiments of the system, the light source is configured to generate a laser beam.

[0047] According to some embodiments of the system, at least one sensor includes a light sensor and / or an image sensor (e.g., a camera).

[0048] According to some embodiments, a method is provided for producing a sample having a pair of outer flat surfaces set at a nominal angle to each other. This method includes the following steps: - The stage of providing unprocessed samples. - A step of processing a raw sample to obtain a processed sample that includes an outer flat first surface and an outer flat second surface set at a certain test angle relative to the first surface. - The step of measuring the test angle using the optical method described above. - If the test angle differs from the nominal angle by a predetermined difference, the processed sample is subjected to further processing, and a reprocessed sample is obtained. - A step in which the difference between the test angle of the reprocessed sample and the nominal angle is measured until it falls below a predetermined difference, and the reprocessing step is repeated as necessary.

[0049] Certain embodiments of this disclosure may include some or all of the above advantages, or may not include any of them. One or more other technical advantages may be readily apparent to those skilled in the art from the drawings, specification and claims included in this application. Furthermore, while specific advantages are listed above, various embodiments may include all or some of the listed advantages, or may not include any of them.

[0050] Unless otherwise specified, all technical and scientific terms used herein have the same meaning as those generally understood by those skilled in the art relating to this disclosure. In case of any conflict, including definitions, this specification shall prevail. The indefinite articles “a” and “an” used herein mean “at least one” or “one or more” unless it is clearly evident from the context.

[0051] Unless otherwise specified, as will be apparent from this disclosure, in some embodiments, terms such as “process,” “calculate,” “operate,” “determine,” “estimate,” “evaluate,” or “measure” may refer to the actions and / or processes of a computer or computing system or similar electronic computing device that manipulate and / or convert data represented as physical (e.g., electronic) quantities in the registers and / or memory of the computing system to other data similarly represented as physical quantities in the memory, registers, or other such information storage, transmission, or display devices of the computing system.

[0052] Embodiments of the present disclosure may include apparatus for performing the operations described herein. The apparatus may include a general-purpose computer that can be specifically constructed for a desired purpose or that can be selectively differential or reconfigured by a computer program stored in the computer. Such computer programs can be stored in computer-readable storage media, such as, but not limited to, 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 or optical cards, or any other type of medium suitable for storing electronic instructions and that can be coupled to a computer system bus.

[0053] The processes and displays presented herein are not inherently associated with any particular computer or other device. Various general-purpose systems can be used with the programs taught herein, or it may be advantageous to construct more specialized devices to perform the desired method. Desired structures for various such systems will be understood from the following description. Furthermore, no specific programming language is referenced in the description of embodiments of this disclosure. It will be understood that various programming languages ​​may be used to implement the teachings of this disclosure as described herein.

[0054] Aspects of this disclosure may be described in the general context of computer executable instructions, such as program modules, that are executed by a computer. Generally, a program module includes routines, programs, objects, components, and data structures that perform a particular task or implement a particular abstract data type. The disclosed embodiments may also be implemented in a distributed computing environment in which tasks are performed by remote processing devices linked over a communication network. In a distributed computing environment, program modules may reside on both local and remote computer storage media, including memory storage devices. [Brief explanation of the drawing]

[0055] Some embodiments of this disclosure will be described with reference to the accompanying drawings. The description, together with the drawings, will make it clear to those skilled in the art how some embodiments may be carried out. The drawings are for illustrative purposes only and do not attempt to show structural details of the embodiments in more detail than is necessary for a fundamental understanding of this disclosure. For clarity, some objects depicted in the drawings are not drawn to scale. Furthermore, two different objects in the same drawing may be drawn to different scales. In particular, the scale of some objects may be significantly exaggerated compared to other objects in the same drawing.

[0056] In the diagram,

[0057] [Figure 1A] A schematic diagram of an optical system for measuring the flat outer surface of a sample during sample testing, according to some embodiments, is shown. [Figure 1B] A schematic perspective view of the sample in Figure 1A during testing, according to one embodiment, is shown. [Figure 1C] A schematic representation of the spot on the photosensitive surface of the sensor in the system shown in Figure 1A, according to some embodiments, is shown. [Figure 2A] This schematic diagram illustrates an optical system for verifying the perpendicularity of one outer flat surface of a sample to two other parallel outer flat surfaces of the sample during sample testing, the system corresponding to a specific embodiment of the system shown in Figure 1A. [Figure 2B] This schematic diagram illustrates an optical system for verifying the perpendicularity of one outer flat surface of a sample to two other parallel outer flat surfaces of the sample during sample testing, the system corresponding to a specific embodiment of the system shown in Figure 1A. [Figure 2C] Figures 2A and 2B schematically show the spots on the photosensitive surface of the sensor in some embodiments of the system. [Figure 2D] Figures 2A and 2B schematically show the spots on the photosensitive surface of the sensor in some embodiments of the system. [Figure 3] This diagram schematically shows an optical system for measuring the flat outer surface of a sample during sample testing, the system corresponding to a specific embodiment of the system in Figure 1A, where the system's optical bending component is a prism. [Figure 4] This diagram schematically illustrates an optical system for measuring the flat outer surface of a sample during sample testing. The system corresponds to a specific embodiment of the system shown in Figure 1A, where the optical bending component of the system is a mirror. [Figure 5] A flowchart of an optical method for measuring the flat outer surface of a sample, according to some embodiments, is shown. [Figure 6] A flowchart of an optical system for verifying the perpendicularity of one outer flat surface of a sample to two other parallel outer flat surfaces of the sample, according to some embodiments, is shown. [Modes for carrying out the invention]

[0058] The principles, use, and implementation of the teachings disclosed herein can be better understood by referring to the appended specification and drawings. A person skilled in the art who has examined the specification and drawings of this application will be able to implement the teachings herein without undue effort or experimentation. In the figures, the same reference numerals refer to the same part throughout.

[0059] In the specification and claims of this application, the words “contains” and “have,” and their forms, are not limited to the components in the list to which those words may be associated.

[0060] As used in this application, the term “about” may be used to specify a value of a quantity or parameter (e.g., the length of an element) within a range of consecutive values ​​in the vicinity of (and including) a given (stated) value. According to some embodiments, “about” may specify a parameter value between 80% and 120% of a given value. For example, the statement “the length of the element is about 1 m” is equivalent to the statement “the length of the element is between 0.8 m and 1.2 m.” According to some embodiments, “about” may specify a parameter value between 90% and 110% of a given value. According to some embodiments, “about” may specify a parameter value between 95% and 105% of a given value.

[0061] As used herein, the terms “substantially” and “about” may be synonymous in some embodiments.

[0062] For the sake of simplicity, some diagrams use a three-dimensional Cartesian coordinate system. Note that the orientation of the coordinate system relative to the depicted objects may vary from diagram to diagram. Also, the symbols...

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[0063] In the diagram, optional elements and optional stages (in the flowchart) are depicted with dashed lines.

[0064] system According to some embodiments, an optical method is provided for measuring the outer flat surface of a sample. Figure 1A schematically depicts an optical-based system 100, which is such a system according to some embodiments. The optical system 100 is configured to verify the angle between two outer flat surfaces of a sample. Figure 1A provides a side view of the system 100 and sample 10 according to some embodiments. (It should be understood that sample 10 does not constitute part of system 100.) Sample 10 is shown in the state being inspected by system 100. Sample 10 can be any opaque or partially transparent element having two or more reflective flat (external) surfaces, these elements set at an (non-zero) angle to each other. According to some embodiments, sample 10 may be made of glass, polymer, metal, crystal, and / or a combination thereof. According to some embodiments, sample 10 may be an optical element such as a prism, waveguide, or beam splitter. According to some embodiments, the prism may be molded as a polyhedron. According to some embodiments, and as also shown in Figure 1A, the cross-section of sample 10 cut parallel to the zx plane can define a polygon.

[0065] Sample 10 includes an outer flat first surface 12a (i.e., the first flat outer surface) and an outer flat second surface 12b (i.e., the second flat outer surface). Sample 10 is manufactured to present a nominal inclination angle α between the first surface 12a and the second surface 12b. However, due to imperfections in manufacturing, the actual inclination angle between the first surface 12a and the second surface 12b, labeled as α' in Figure 1A, will generally differ from the nominal inclination angle α. In Figure 1A, a dashed line L intersects the second surface 12b and is inclined at the nominal inclination angle α relative to the first surface 12a. The dashed line L indicates the intended inclination of the second surface 12b. The nominal inclination angle α may be acute (i.e., α < 90°), obtuse (i.e., α > 90°), or equal to 90°.

[0066] Furthermore, Figure 1A shows a dashed line H (straight line) that extends parallel to the first surface 12a and intersects with the second surface 12b. The supplementary angle to the nominal inclination angle α is labeled as β (i.e., β = 180° - α) and extends between the second surface 12b and the dashed line H.

[0067] According to some embodiments, system 100 includes an optical bending component (LFC) 102, and an illumination and collection device (or assembly, ICA) 104. System 100 may further include a controller 108 functionally associated with the ICA 104 and configured to control its operation. According to some embodiments, and also illustrated in Figure 1A, the ICA 104 includes a light source 112 (or more light sources) and a sensor 114 (or more sensors), and optionally, an optical instrument 118. According to some embodiments, the sensor 114 is an optical sensor or an image sensor (or, multiple sensors include one or more optical sensors and / or one or more image sensors, e.g., a camera). According to some alternative embodiments not depicted in Figure 1A, the ICA 104 includes an eyepiece assembly instead of the sensor 114, thereby configured for visual determination (i.e., by eye) of the actual tilt angle. The light source 112 and the optical instrument 118 are collectively referred to as the “photo-generating assembly”.

[0068] As will be described in detail below, ICA104 is configured to output a pair of parallel light beams (LBs), namely a first LB105a (also called the “first incident LB,” shown in Figure 1A by a pair of parallel rays) and a second LB105b (also called the “second incident LB,” shown in Figure 1A by a pair of parallel rays). According to some such embodiments, the optical instrument 118 may be configured to collimate the light generated by the light source 112, thereby generating the (parallel) incident LBs 105a and 105b. According to such embodiments, the optical instrument 118 may include a collimating lens or a collimating lens assembly (not shown). According to some embodiments, the incident LBs 105a and 105b may form complementary portions of a collimated light beam (focused by the collimating lens or collimating lens assembly). Alternatively, according to some embodiments, the incident LBs 105a and 105b may be spaced apart (and parallel). According to some such embodiments, the optical instrument 118 may further include one or more optical filters (e.g., light-absorbing filters or opaque plates), and / or one or more beam splitters, and optionally one or more mirrors (not shown) configured to prepare a pair of spaced-out parallel beams from a collimated beam.

[0069] According to some embodiments, the optical instrument 118 may include a plurality of blocking elements (such as a pair of blocking elements shown in Figures 2A and 2B) configured to selectively block each of the incident LB105, thereby enabling separate sensing of each of the return LBs induced by the first incident LB105a and the second incident LB105b, respectively. As used herein, the term “blocking element” with respect to an optical element is broadly interpreted to include both openable and closable opaque elements (such as shutters) configured to block an incident light beam (when closed) and filtering elements (such as spectral filters) configured to completely or partially block one or more portions of the light spectrum (e.g., the visible spectrum).

[0070] According to some embodiments, the light source 112 may be configured to produce polychromatic light. According to some such embodiments, the spectrum of light may be controllable. According to some embodiments, the light source 112 may be configured to produce monochromatic light. In this regard, it should be noted that it may be preferable to use monochromatic light when LFC 102 is a prism and the second incident LB 105b is generated to strike the prism non-perpendicularly (for example, when the first incident LB 105a is generated to strike the first surface 12a non-perpendicularly).

[0071] According to some embodiments, ICA104 is an autocollimator or includes an autocollimator (i.e., some or all of the light source 112, sensor 114, and optical instrument 118 constitute components of the autocollimator). According to some embodiments, incident LB105 constitutes adjacent partial beams of a single collimated wide-range LB generated by the autocollimator. According to such embodiments, optical instrument 118 may include an optical filter configured to transmit two partial beams (such as incident LB105) of a collimated LB prepared by the autocollimator and incident on the optical filter (the parallelism of the two partial beams is maintained when they exit the optical filter).

[0072] According to some embodiments, the light source 112 may be configured to generate a collimated laser beam. According to some such embodiments, the optical instrument 118 may include a beam expander (not shown) configured to increase the laser beam diameter, so that the expanded laser beam can strike both the sample 10 and the LFC 102 simultaneously. In such embodiments, the first incident LB105a and the second incident LB105b may constitute complementary portions of the laser beam. Alternatively, the optical instrument 118 may include a beam splitter and optical components configured to split the laser beam into a pair of parallel (spaced) subbeams, namely, a first subbeam and a second subbeam constituting the first incident LB105a and the second incident LB105b, respectively. According to some such embodiments, the optical instrument 118 may be configured to recombine the return subbeams (i.e., the first return LB133a and the second return LB133b) so that each of the subbeams is redirected onto a single photosensor (i.e., sensor 114 according to some embodiments) and focused onto the photosensitive surface of the photosensor (e.g., using a lens or lens device). Ideally, when the second subbeam strikes the internal facet 14 perpendicularly (after redirection by LFC 122 and transmission to sample 10), the recombined subbeams will form a collimated (second) laser beam, and the two spots formed on the photosensor by the return subbeams will overlap. According to some other embodiments, two photosensors can be used such that their distance from each other and their relative orientation are known. In such embodiments, each of the return subbeams may be directed onto a different photosensor of the two photosensors.

[0073] According to some embodiments, ICA104 may be configured for interference spectroscopy. The light source 112, some or all of the optical instrument 118, and the sensor 114 constitute components of the interference apparatus, as described below. In such embodiments, the light source 112 may be configured to generate a coherent and planar wavefront. The optical instrument 118 may be configured to split the generated wavefront into two wavefronts: a first (coherent and planar) incident wavefront and a second (coherent and planar) incident wavefront, which constitute a first incident LB105a and a second incident LB105b, respectively.

[0074] According to some embodiments, LFC102 is a prism, one or more mirrors, and / or a diffraction grating, or includes them. According to some embodiments, LFC102 is a pentaprism or a prism of similar function that is unaffected by pitch variations (meaning that its optical bending angle remains unchanged when the pitch of LFC changes slightly, i.e., when LFC102 rotates slightly around the y-axis).

[0075] According to some embodiments, the system 100 may further include an orientation infrastructure 120 for oriented the sample 10 relative to the ICA 104. In a non-limiting example, the orientation infrastructure 120 may take the form of a stage 122 mounted on a base 124. The stage 122 is configured to mount a sample, such as the sample 10, on it. The base 124 is configured to orient the stage 122 and optionally to translate it. In some embodiments, the base 124 may be configured to allow manipulation of the sample 10 in each of six degrees of freedom (i.e., translation in any direction, rotation about the yaw axis, and rotation about (at least limited) pitch and roll axes). In particular, the orientation infrastructure 120 may be configured to orient the sample 10 so that the first incident LB 105a strikes perpendicularly onto the first surface 12a, and the bent LB 113b obtained by striking the second incident LB 105b onto the LFC 102 strikes nominally perpendicularly onto the second surface 12b. In some embodiments, the orientation infrastructure 120 may be functionally associated with and configured to be controlled by a controller 108.

[0076] Where used herein, the terms “nominal” and “ideally” may be synonymous depending on certain embodiments. When an object is designed and manufactured to exhibit (i.e., be characterized by) a certain intrinsic property (such as the angle of inclination between flat surfaces of a sample), it can be said that the object “nominal” exhibits that property; however, in practice, due to manufacturing tolerances, the object may only exhibit that property imperfectly. This also applies to the extrinsic properties of an object, such as the direction of light propagation of a light beam. In this case, the object may be intentionally prepared or otherwise manipulated to ideally present that property; however, in practice, due to inherent imperfections in the equipment used for its preparation, the object may only exhibit that property imperfectly.

[0077] During operation, the first incident LB105a is directed at sample 10, and the second incident LB105b is directed at LFC102. According to some embodiments, and as also illustrated in Figure 1A, the first incident LB105a is incident perpendicular to the first surface 12a. The first incident LB105a (or at least a portion thereof) is reflected from the first surface 12a, as indicated by the first return LB125a, and sensed by the sensor 114.

[0078] The second incident LB105b is directed in LFC102. LFC102 is nominally configured to bend the second incident LB105b at a nominal inclination angle α. More precisely, LFC102 is configured to "bend" (i.e., change direction) the second incident LB105b, so that the bent LB113b (obtained by the bending of the second incident LB105b) is nominally directed upward at a nominal inclination angle α with respect to the second incident LB105b and (nominally) perpendicular to the second surface 12b. In practice, due to manufacturing imperfections, the actual optical bending angle α'' of LFC102 may deviate slightly from the nominal inclination angle α. If the uncertainty in the optical bending angle of LFC102 (due to manufacturing tolerances) is significantly lower than the precision required to determine the actual tilt angle of the second surface 12b, then the uncertainty in the optical bending angle can be ignored (i.e., LFC102 can be considered to bend the second incident LB105a at the exact nominal tilt angle α). Otherwise, the uncertainty in the optical bending angle will have a (non-negligible) impact on the overall uncertainty in the measured value of the actual tilt angle, unless the nominal tilt angle is equal to 90°, in which case the deviation in the actual bending angle can be discounted by performing additional measurements with the sample inverted, as detailed below in the descriptions of Figures 2A and 2B and Figure 6.

[0079] To avoid cluttering the diagrams, typically only two rays of each light beam are shown. Furthermore, the depiction of the light beams is schematic, and it should be understood that the depicted light beams may be wider or narrower than those depicted. Therefore, for example, according to some embodiments, the first incident LB105a may strike the entire first surface 12a, and / or the second incident LB105b may strike the entire light-receiving surface of LFC102.

[0080] The bent LB113b strikes the second surface 12b at an incident angle θ. The angle is measured clockwise from the viewpoint of the reader viewing the figure. Angles greater than 180° are set to negative values ​​by subtracting 360°. Thus, in Figure 1A, as a non-limiting example intended to facilitate explanation by being more specific, the incident angle θ is negative and the return angle (i.e., the reflection angle) is positive. More precisely, the incident angle θ is shown extending counterclockwise from the dashed line B, which is the normal to the second surface 12b for the ray 113b1 (one of the two rays showing the bent LB113b in Figure 1A). The inclination angles α and α' are measured clockwise from the first surface 12a (in Figure 1A, as a non-limiting example intended to facilitate explanation, α' is shown as greater than α). The nominal inclination angle α extends clockwise from the first surface 12a to the dashed line L. The actual inclination angle α' extends clockwise from the first surface 12a to the second surface 12b.

[0081] The incident angle θ depends on the deviation Δα' = α - α' (i.e., the deviation of the inclination of the second surface 12b from the nominal inclination) and the deviation Δα'' = α - α'' (i.e., the deviation of the actual optical bending angle of LFC102 from α). If there are no imperfections in system 100 (i.e., α'' = α), the incident angle θ is equal to Δα'. In other words, the incident angle θ is equivalent to Δα' for accuracy, which depends on the uncertainty in the actual optical bending angle α'', as well as any other relevant uncertainties in the parameters of LFC102, ICA104, and orientation infrastructure 120. In particular, system 100 is configured to output LB113b that strikes nominally perpendicular (i.e., vertically) on the second surface 12b when Δα' = 0. The magnitude of Δα' (i.e.,

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[0082] The bend LB113b (or at least a part thereof) is reflected specularly from the second surface 12b, as shown by the reflection LB117b (i.e., the return angle θ is equal to the negative incident angle θ). R It is reflected.

[0083] The reflected light LB117b returns towards LFC102, where it is bent at the actual optical bending angle α''. More precisely, the reflected light LB117b is redirected by LFC102 towards ICA104, as indicated by the second returning light LB125b. The second returning light LB125b is detected by sensor 114.

[0084] Typically, due to manufacturing imperfections in both Sample 10 and LFC102, the second return LB125b will no longer be parallel to the first return LB125a. The angle δ (also called the "angle deviation") between the first return LB125a and the second return LB125b will be 2·θ RIt is equal to and therefore depends on Δα'. The angle δ is shown extending clockwise from ray 105b1 (one of the two rays indicating the second incident LB105b in Figure 1A) to ray 125b1 (one of the two rays indicating the second return LB125b in Figure 1A), and is therefore positive in Figure 1A.

[0085] Also, referring to Figure 1B, which shows a schematic perspective view of sample 10 during sample inspection by system 100. Figure 1B also shows the first incident LB105a, the first return LB133a, the bent LB113b (which should be understood as striking nominally perpendicularly on the second surface 12b), and the reflected LB117b.

[0086] Figure 1C schematically shows the first spot 133a and the second spot 133b formed on the photosensitive surface 134 of the sensor 114 by the first return LB125a and the second return LB125b, respectively, according to one embodiment, where u1 and u2 are the horizontal coordinates (i.e., measured along the x-axis) of the first spot 133a and the second spot 133b, respectively. (It is assumed that the coordinate system depicted in Figure 1C coincides with the coordinate system depicted in Figure 1A to the translation of the possible origin. Thus, the x-axis in Figure 1C 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, if the measurement is based on an autocollimator (i.e., ICA104 is an autocollimator or an embodiment including one), then δ = Δu / f, and consequently 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) for accuracy that depends on uncertainty in the actual optical refraction angle α'' and any other relevant uncertainty in the parameters of LFC102, ICA104, and orientation infrastructure 120).

[0087] According to some embodiments, and as also illustrated in Figure 1C, the vertical coordinates of the first spot 133a and the second spot 133b (i.e., when measured along the y-axis) may differ slightly from each other due to misalignment of the LFC 102 and the sample 10, for example, with respect to their respective yaw angles (i.e., around the z-axis). Such potential misalignment can be minimized during the calibration of the system 100, for example, by using an autocollimator.

[0088] Alternatively, according to some embodiments in which ICA104 is an interferometer or includes one, the angle δ can be estimated from the interference pattern formed by the first return LB125a and the second return LB125b. More specifically, in such embodiments, the first return LB125a constitutes a first return wavefront obtained from the reflection of the first incident wavefront from the first surface 12a, and the second return LB125b constitutes a second return wavefront obtained from the bending of the second incident wavefront by LFC102, the reflection from the second surface 12b, and a second bending by LFC102. The return wavefronts are recombined and their interference pattern is measured by sensor 114. If the first and second wavefronts strike their respective surfaces (i.e., the first surface 12a or the second surface 12b, respectively) at right angles, the recombined wavefronts will form a uniform pattern on sensor 114. If the second surface 12b deviates from its nominal slope, the recombined wavefront forms a periodic pattern on the sensor 114. The deviation Δα' can be inferred from the periodicity of this pattern.

[0089] According to some embodiments, the controller 108 may be communicably associated with a computing module 130. The computing module 130 may include a processor, as well as volatile and / or non-volatile memory components. The processor may be configured to receive data from the controller 130, sensor 114 data (i.e., values ​​of u1 and u2), and to calculate Δα' based on them. Optionally, according to some embodiments, the processor may be further configured to calculate the uncertainty in Δα' (the calculated value), taking into account manufacturing tolerances and imperfections of the LFC 102 (including uncertainty in the actual optical bending angle), ICA 104, and orientation infrastructure 120. According to some embodiments, the computing module 130 may be included in the system 100.

[0090] According to some embodiments, the system 100 may further include two shutters (positioned similarly to the shut-off elements in Figures 2A and 2B) configured to allow selective shut-off of each of the first return LB125a and the second return LB125b, so that each of the return LBs 125 can be sensed separately (thus facilitating attributing each of the spots 133 to the return LB that induced the spot).

[0091] According to some embodiments, the first surface 12a and the second surface 12b may be coated or temporarily coated with a reflective coating material, so that incident light on the surface is reflected to the maximum extent, or reflection from the surface is at least increased. According to some embodiments in which the light source 112 is configured to produce polychromatic light, the first surface 12a may be coated with a first coating material configured to reflect light in a first spectrum, and the second surface 12b (or LFC 102) may be coated with a second coating material configured to reflect light in a second spectrum, the second spectrum not overlapping with the first spectrum or substantially not overlapping with it. In such embodiments, selective blocking of the first return LB 125a and the second return LB 125b may be carried out using a spectral filter or spectral filter device (optionally instead of a shutter) configured to allow each of the return LB 125 to be incident on the coating material and to selectively block or at least partially block light from the second spectrum and the first spectrum, respectively.

[0092] According to some alternative embodiments, a first (passive) spectral filter can be used to filter the first incident LB105a into the first spectrum, and a second (passive) spectral filter can be used to filter the second incident LB105b into the second spectrum. In such embodiments, an additional spectral filter can be used, positioned between the spectral filter and the sensor 114, and capable of selectively filtering either the light into the first or second spectrum, in order to enable each of the return LB125 to be sensed separately.

[0093] It should be noted that a spectral filter or spectral filtering device can be used to reduce the signal associated with stray light and associated with any one of the incident LB105s that reaches the sensor 114.

[0094] In Figure 1A, 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 such a morphological sample. In particular, any sample including an outer flat first surface and an outer flat second surface that is inclined relative to the first surface but does not share a common edge with it can also be subjected to measurement using System 100 as described above.

[0095] Figures 2A and 2B schematically illustrate an optical system 200 for verifying the perpendicularity of one outer flat surface of a sample to at least two other outer flat surfaces of the sample, which are parallel to each other, according to some embodiments. System 200 corresponds to a specific embodiment of system 100. More specifically, Figure 2A provides a side view of system 200 and the sample 20 being inspected by system 200, according to some embodiments. Sample 20 may be an optical element such as a prism, waveguide, or beam splitter. According to some embodiments, the prism may be formed as a polyhedron. According to some embodiments, as also illustrated in Figures 2A and 2B, the cross section of sample 20 may be cut parallel to the zx plane to define a polygon.

[0096] Sample 20 includes an outer flat first surface 22a, an outer flat second surface 22b, and an outer flat third surface 22c. The first surface 22a and the third surface 22c are nominally parallel by design. Furthermore, Sample 20 is manufactured to present a nominal inclination angle of 90° between the first surface 22a and the second surface 22b. However, due to imperfections in the manufacturing process, the actual inclination angle of the second surface 22b relative to the first surface 22a, labeled as χ' in Figures 2A and 2B, will generally differ from 90°.

[0097] It should be noted that when using state-of-the-art manufacturing techniques, the (manufacturing) tolerance for the actual angle between surfaces that are manufactured to be parallel is sufficiently smaller than the tolerance for the actual angle between surfaces that are manufactured to be non-parallel. Therefore, since the first surface 22a and the third surface 22c are manufactured to be parallel, the deviation from the parallelism of their planes is expected to be negligible compared to the deviation of the actual inclination angle χ' from 90°. Thus, the actual angle ψ' (also called the "actual supplemental angle") between the second surface 22b and the third surface 22c is 180°-χ ’ That is, the actual tilt angle χ ’ This can be interpreted as being equal to the supplementary angle with respect to ψ'. (The nominal value of the actual supplementary angle ψ' is 90°.)

[0098] System 200 includes LFC202 and ICA204. LFC202 corresponds to a specific embodiment of LFC102 and is configured to bend light nominally up to 90°. According to some embodiments, LFC202 is a prism, one or more mirrors, or a diffraction grating, which is nominally configured to bend light incident on its upper surface up to 90° in a direction perpendicular to the first surface 22a. According to some embodiments, LFC202 is a pentaprism or a prism with a similar function (i.e., unaffected by pitch variations).

[0099] ICA204 corresponds to a specific embodiment of ICA104 and includes a light source (not shown), a sensor (not shown), and optionally, optical equipment (not shown) corresponding to specific embodiments of light source 112, sensor 114, and optical equipment 118, respectively. According to some embodiments, ICA204 includes an autocollimator 240. The autocollimator 240 may be configured to generate a collimated LB201. A first incident LB205a and a second incident LB205b form a subbeam of LB201. According to some embodiments, and also as shown in Figures 2A and 2B, ICA204 may further include a pair of shut-off elements 246a and 246b, which enable selective shut-off of each of the first incident LB205a and the second incident LB205b. According to some embodiments, each of the shut-off elements 246a and 246b may be a shutter (e.g., controllable by a controller 208).

[0100] The first incident LB205a is directed at sample 20, and the second incident LB205b is directed at LFC202. According to some embodiments, and also as shown in Figure 2A, ICA204 and sample 20 are positioned and directed so that the first incident LB205a is incident on the first surface 22a perpendicular to that surface. The first incident LB205a (or at least a portion thereof) is reflected from the first surface 22a, as indicated by the first return LB225. The first return LB225a is sensed by the autocollimator 240.

[0101] LFC202 is configured to bend the second incident LB205b nominally to 90°. More precisely, LFC202 is configured to bend the second incident LB205b, so that the (first) bent LB213b (obtained by the bending of the second incident LB205b) is nominally oriented upward at 90° relative to the second incident LB205b and nominally oriented perpendicular to the second surface 12b. In practice, due to manufacturing imperfections in embodiments where LFC202 is susceptible to pitch variations, and misalignment, the actual optical bending angle χ'' of LFC202 may deviate slightly from 90°. As detailed below, the effects of manufacturing imperfections in LFC202 can be offset or substantially offset by inverting the sample 20 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 LFC202), and by repeating the measurements described in the description of Figure 2B.

[0102] The bent LB213b strikes the second surface 22b at a first angle of incidence η1. The first angle of incidence η1 depends on the deviation Δχ' = 90° - χ' (i.e., the deviation of the inclination of the second surface 22b from the nominal inclination) and the deviation Δχ'' = 90° - χ'' (i.e., the deviation of the actual optical bending angle of LFC202 from 90°). The normal to the second surface 22b is shown in Figure 2A by the dashed line C1 (straight line).

[0103] The bent LB213b (or at least a portion thereof) is reflected specularly from the second surface 22b (i.e., with a return angle ζ1 equal to the negative value of the first incident angle η1), as indicated by the (first) reflected LB217b. The reflected LB217b returns towards LFC202 and is bent by LFC202 at the actual optical bending angle χ'', resulting in the second return LB225b. The second return LB225b is sensed by sensor 214.

[0104] The angle δ1 (also called the "first angular deviation") between the second return LB225b and the first return LB225a is equal to 2·ζ1. Therefore, the angle δ1 depends on Δχ'. Figure 2C schematically shows the first spot 233a and the second spot 233b formed by the first return LB225a and the second return LB225b, respectively, on the photosensitive surface 234 of the autocollimator 240 according to one embodiment, where w1 and w2 are the horizontal coordinates of the first spot 233a and the second spot 233b (i.e., measured along the axis), respectively. The angle δ1 can be directly inferred from the difference Δw = w2 - w1.

[0105] Referring to Figure 2B, compared to Figure 2A, sample 20 is inverted 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 LFC202).

[0106] The third incident LB205a' is oriented perpendicular to sample 20, and the fourth incident LB205b' is oriented in LFC202. The third incident LB205a' (or at least a portion thereof) is reflected from the third surface 22c, as indicated by the third return LB225a'. The third return LB225b' is sensed by sensor 214.

[0107] The fourth incident LB205b' strikes LFC202, resulting in the second bend LB213b'. The second bend LB213b' is at the second incident angle η 2 It then strikes the second surface 22b. The second angle of incidence η2 is the deviation

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[0108] As indicated by the second reflection LB217b', the fourth incident LB205b' is reflected (at least partially) mirror-like from the second surface 22b (i.e., with a return angle ζ2 equal to the negative value of the second incident angle η2). The second reflection LB217b' returns towards LFA202, as indicated by the fourth return LB225b', and is bent by LFA202 at the actual light bending angle χ'. The fourth return LB225b' is sensed by sensor 214.

[0109] The angle δ2 (also called the "second angular deviation") between the fourth return LB225b' and the third return LB225a' is equal to 2·ζ2. Thus, the angle δ2 depends on Δψ', and by extension, on Δχ' (since χ'+φ'=180°, the result is Δψ'=-Δχ'). Figure 2D schematically shows the third spot 233a' and the fourth spot 233b' formed by the third return LB225a' and the fourth return LB225b', respectively, on the photosensitive surface 234 of the sensor 214 according to one embodiment, where w1' and w2' are the horizontal coordinates of the third spot 233a' and the fourth spot 233b', respectively. The angle δ2 can be directly estimated from the difference Δw'=w2'-w1'.

[0110] In Figures 2C and 2D, Δw and Δw' are shown as both being negative (and consequently, δ1 and δ2 are both negative), but it can be understood that in general, Δw and Δw' can have opposite signs (and consequently, δ1 and δ2 will have opposite signs), or they can both be positive (and consequently, δ1 and δ2 are both positive).

[0111] Using the measured angles δ1 and δ2, we can provide respective estimates of the deviation angle Δχ'. If the system 200 is perfect, η2 is equal to -η1 and δ1 is equal to -δ2. However, in practice, the two estimates are generally different due to the actual optical bending angle deviating from its nominal value. Since δ1 and δ2 have the same or substantially the same dependence on the actual optical bending angle (i.e., both δ1 and δ2 increase with increasing χ'' and decrease with decreasing χ'') (assuming the LFC is unaffected by pitch variations), the deviation of the optical bending angle can be offset or substantially offset by averaging it over 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 in which ICA204 is an autocollimator or includes one, <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.

[0112] 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 material, so that light entering the reflective coating material is reflected to the maximum extent, or at least the reflection from there is increased. According to some embodiments in which the autocollimator 240 is configured to produce a multicolor LB, the first surface 12a and the third surface 12c may be coated with a first coating material configured to reflect light in a first spectrum, and the second surface 12b may be coated with a second coating material configured to reflect light in a second spectrum, the second spectrum being different from the first spectrum. In such embodiments, the autocollimator 240 may include a spectral filter configured to allow selective filtering of light in the first spectrum or the second spectrum, thereby facilitating the separate sensing of each of the return LBs 225.

[0113] In some embodiments, the blocking elements 246a and 246b can be spectral filters (specifically, dichromatic filters) configured to block light in the second spectrum and the first spectrum. In such embodiments, additional spectral filters can be used, positioned between the blocking elements 246 and the autocollimator 240, or contained within the autocollimator 240, and configured to selectively filter light in the first spectrum or the second spectrum, in order to enable separate sensing of each of the return LB225.

[0114] In Figures 2A and 2B, the second surface 22b is shown as extending from the first surface 22a to the third surface 22c; however, it should be understood that the scope of this disclosure is not limited to the measurement of such a molded sample. In particular, any sample including an outer flat first surface, an outer flat second surface inclined with respect to the first surface, and an outer 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 with the third surface, can also be subjected to measurement using the system 200 as described above.

[0115] According to some alternative embodiments not shown in Figures 2A and 2B, the light source 212 and optical instrument 218 may be configured to produce an expanded (collimated) laser beam, or a pair of parallel and spaced-out (collimated) laser beams, as essentially described above in the description of System 100. According to yet another embodiment, ICA 204 may be or include an interferometer, as described above in the description of System 100.

[0116] Figure 3 schematically illustrates an optical system 300 for verifying the angle between two outer flat surfaces of a sample, according to some embodiments. System 300 corresponds to a specific embodiment of System 100 in which the LFC is a prism or includes a prism. More specifically, Figure 3 provides a side view of System 300 and the sample 10 being inspected by System 300, according to some embodiments. System 300 includes a prism 302, an ICA 304 (its components are not shown), and an orientation infrastructure 320. According to some embodiments, and also as illustrated in Figure 3, System 300 further includes a controller 308 and, optionally, a computing module 330. The prism 302, ICA 304, orientation infrastructure 320, controller 308, and computing module 330 correspond to specific embodiments of LFC 102, ICA 104, orientation infrastructure 120, controller 108, and computing module 130, respectively.

[0117] According to some embodiments, the prism 302 may be unaffected by pitch variations—i.e., rotations about the y-axis—at least over a continuous range of pitch angles. According to some such embodiments, as depicted in Figure 3, the prism 302 may be a pentaprism or a prism having a similar function, and may be, for example, a prism including an even number of internal reflective surfaces. According to some alternative embodiments not shown in Figure 3, instead of the prism 322, the system 300 may include two mirrors set relative to each other at the same angle as the two surfaces of the prism 302 (the first pentaprism surface 328a and the second pentaprism surface 328b), and the two surfaces of the prism internally reflect the transmitted portion of the second incident LB305b.

[0118] Figure 3 shows the first incident LB305a, the first return LB325a, the second incident LB305b, the bent LB313b, the reflected LB317b, and the second return LB325b, which correspond to specific embodiments of the first incident LB105a, the first return LB125a, the second incident LB105b, the bent LB113b, the reflected LB117b, and the second return LB125b, respectively. The trajectories of the second incident LB305b and the reflected LB317b within the prism after they have entered the prism 302 are also shown. The transmitted portions of the second incident LB305b after it has entered the prism 302, after reflection within it, and after two reflections within it are numbered 309b1, 309b2, and 309b3, respectively. The transmitted portions of the reflected LB317b after refraction by prism 302, after reflection within it, and after two reflections within it are numbered 321b1, 321b2, and 321b3, respectively.

[0119] The angle of incidence of the bend LB313b on the second surface 12b is labeled as 63. The angular deviation of the second return LB325b from the first return LB325a is labeled as 83.

[0120] Figure 4 schematically shows an optical system 400 for verifying the angle between two outer flat surfaces of a sample, according to some embodiments. System 400 corresponds to a particular embodiment of system 100, in which case LFC is a mirror or includes one. More specifically, Figure 4 provides a side view of system 400 and sample 10 being inspected by system 400, according to some embodiments. System 400 includes a mirror 402, an ICA 404 (its components are not shown), and an orientation infrastructure 420. According to some embodiments, and also as illustrated in Figure 4, system 400 further includes a controller 408 and, optionally, a computing module 430.

[0121] The mirror 402, ICA 404, orientation infrastructure 420, controller 408, and computing module 430 correspond to specific embodiments of the LFC 102, ICA 104, orientation infrastructure 120, controller 108, and computing module 130, respectively.

[0122] According to some embodiments, and as also shown in Figure 4, the mirror 402 may be a planar mirror.

[0123] Figure 4 shows the first incident LB405a, the first return LB425a, the second incident LB405b, the bent LB413b, the reflected LB417b, and the second return LB425b, which correspond to specific embodiments of the first incident LB105a, the first return LB125a, the second incident LB105b, the bent LB113b, the reflected LB117b, and the second return LB125b, respectively.

[0124] The angle of incidence of the bend LB413b on the second surface 12b is labeled as θ4. The angular deviation of the second return LB425b from the first return LB425a is labeled as δ4.

[0125] method According to some embodiments, an optical method is provided for measuring the outer flat surface of a sample. This method can be used to verify the orientation of one outer flat surface of a sample relative to another outer flat surface of the sample. Figure 5 shows a flowchart of such a method, i.e., the optical method 500, according to some embodiments. Method 500 may include the following steps: - An optional step 505 in which the system used to implement the method (e.g., system 100) is calibrated. -Step 510 provides a sample to be tested (e.g., sample 10). The sample comprises an outer flat first surface (e.g., first surface 12a) and an outer flat second surface (e.g., second surface 12b) nominally inclined upward at a nominal inclination angle (e.g., nominal inclination angle α) relative to the first surface. - This is stage 520, in which a first incident LB (e.g., first incident LB105a) directed to the first surface and a second incident LB (e.g., second incident LB105b) parallel to the first incident LB are generated (e.g., by the light source 112 and optical instrument 118). -This is stage 530, where a first return LB (e.g., first return LB125a) is obtained by reflecting the first incident LB from the first surface. - This is step 540, where the second incident LB is nominally bent upward at an optical bending angle equal to the nominal inclination angle, the bent LB (e.g., bent LB113b) is reflected from the second surface, and the reflected LB (e.g., reflected LB117b) is nominally bent upward at the optical bending angle, thereby obtaining the second return LB (e.g., second return LB125b). - At stage 550, the angular deviation of the second return LB relative to the first return LB is measured (for example, using sensor 114 or autocollimator 240). -This is step 560, where the actual inclination angle of the second surface relative to the first surface is estimated, at least based on the measured angular deviation.

[0126] As used herein, the term “acquisition” can be used in both active and passive senses. Therefore, for example, the acquisition of the first return LB in step 540 may not result from an action implemented in step 540, but rather from the generation of the first incident LB in step 520. Generally, a step may represent an active action performed by the user or by the system used to implement the method, and / or the result or effect of one or more actions performed in one or more preceding steps.

[0127] Method 500 can be carried out using any one of the optical systems, for example, optical systems 100, 300, and 400, or similar optical systems as described above in their respective descriptions. In particular, according to some embodiments, Method 500 may be based on an autocollimator, based on measuring the distance between laser beams, or based on interferometry, as detailed in the descriptions of various embodiments of System 100. In step 540, the bent LB can be obtained from the second incident LB using any one of the LFC 102, prism 302, and mirror 402, or an LFC of similar function. Similarly, the second return LB can be obtained from the reflected LB using any one of the LFC 102, prism 302, and mirror 402, or an LFC of similar function.

[0128] According to some embodiments, in step 520, the first incident LB may be projected onto the first surface perpendicular to the first surface (i.e., perpendicular). Thus, in such embodiments, the bent LB (obtained from the bending of the second incident LB) will strike the second surface nominally perpendicular. According to some embodiments, in step 505, an “absolute reference” (GS) sample may be used as part of the calibration of the system used to carry out method 500. More specifically, given a sample to be inspected, a corresponding GS sample (i.e., a known sample to present the required geometric shape with high precision) may be used when calibrating the system. In particular, the GS sample can be used to align the oriented stage (e.g., stage 122) and the LFC on which the sample is mounted, so that the bent LB strikes perpendicularly (to the precision provided by the GS sample) on the second surface (similar to the second surface 12b) of the GS sample. Further use of the GS sample allows the stage to be oriented so that the first incident beam (LB) strikes perpendicularly onto the first surface of the GS sample (similar to the first surface 12a). Whether or not a portion of the system's ICA (e.g., ICA104) is included in the system, an autocollimator can be used to perform alignment and verify the perpendicularity of the first incident beam (LB).

[0129] According to some embodiments, once a sample to be tested is provided and, for example, placed on an orientable stage, calibration or additional calibration may be performed after step 510. Additional calibration may include, for example, orienting or reorienting the stage (e.g., using an autocollimator) so that a first incident LB strikes perpendicularly onto a first surface (of the sample being inspected).

[0130] According to some embodiments, in step 520, an autocollimator (e.g., autocollimator 240) can be used to generate a single incident LB, and the first and second incident LBs constitute a subbeam within the single incident LB. Alternatively, an expanded (collimated) laser beam can be generated, and the first and second incident LBs constitute a subbeam within that laser beam. In some other embodiments, a pair of parallel and spaced-apart laser beams can be generated, with the first and second incident LBs corresponding to them, respectively.

[0131] In some embodiments, in steps 530 and 540, a return LB may be sensed using an autocollimator (e.g., autocollimator 240, more generally, the same autocollimator in embodiments where the autocollimator is used to prepare the incident LB). In some embodiments, as essentially described above in the description of Figure 1A and Figures 2A and 2B, a shutter and / or spectral filter may be used to selectively or partially block the first or second return LB. In addition to facilitating the attribution of each of a pair of spots (spots on the photosensitive surface of a light or image sensor (e.g., sensor 114) used to sense the return LB) to the return LB that formed the spot, blocking one return LB may serve to improve measurement accuracy by attenuating the signal associated with stray light while simultaneously sensing the other return LB.

[0132] According to some embodiments, particularly those in which steps 520, 530, and 540 are carried out using an autocollimator (such as autocollimator 240), in step 550, the angular deviation of the second return LB relative to the first return LB is

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[0133] At stage 560, the actual inclination angle

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[0134] Figure 6 shows a flowchart of an optical method 600 for measuring the outer flat surface of a sample, according to some embodiments. Method 600 corresponds to a specific embodiment of Method 500 and can be used to verify the perpendicularity of the outer flat surface of a sample to at least two other outer flat surfaces of the sample, where those surfaces are parallel to each other. Method 600 may include the following steps: -Step 605 provides a sample to be tested (e.g., sample 20). The sample includes an outer flat first surface (e.g., first surface 22a), an outer flat second surface nominally inclined upward at a nominal inclination angle with respect to the first surface (e.g., second surface 22b), and an outer flat third surface parallel to the first surface (e.g., third surface 22c). - This is step 610, in which a first incident LB (e.g., first incident LB205a) oriented perpendicular to the first surface, and a second incident LB (e.g., second incident LB205b) parallel to the first incident LB are generated (e.g., by the autocollimator 240). - This is stage 615, where the first return LB (e.g., the first return LB225a) is obtained from the reflection of the first incident LB from the first surface. - This is stage 620, where a second return LB (e.g., second return LB225b) is acquired by nominally bending the second incident LB nominally upward at an optical bending angle equal to the nominal inclination angle, reflecting the bent LB (e.g., first bent LB213b) from the second surface, and nominally bending the reflected LB (e.g., first reflected LB217b) nominally upward at the optical bending angle. -This is stage 625, where the first angular deviation of the second return LB relative to the first return LB is measured. -This is step 630, where the sample is inverted, resulting in the first and third surfaces being reversed while maintaining the nominal orientation of the second surface. - This is step 635, in which a third incident LB (e.g., third incident LB205a') oriented perpendicular to the third surface, and a fourth incident LB (e.g., fourth incident LB205b') parallel to the third incident LB are generated (e.g., by the autocollimator 240). -This is stage 640, where a third return LB (e.g., third return LB225a') is obtained from the reflection of the third incident LB from the third surface. - This is stage 645, where a fourth return LB (e.g., fourth return LB225b') is obtained by nominally bending the fourth incident LB at the optical bending angle, reflecting the bent LB (e.g., second bent LB213b') from the second surface, and nominally bending the reflected LB (e.g., second reflected LB217b') at the optical bending angle. - At stage 650, the second angular deviation between the fourth return LB and the third return LB is measured. -This is stage 655, where the actual inclination angle of the second surface relative to the first surface is estimated based on the measured first and second angular deviations.

[0135] Method 600 can be carried out using an optical system such as the optical system 200 or a similar optical system, as described above in the description of Figures 2A to 2D. In particular, according to some embodiments, Method 600 may be an autocollimator based on distance measurement between laser beams or based on interference spectroscopy. In step 620, the first bent LB and the second return LB can 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 nominally configured to bend the light incident on the top up to 90° in a direction perpendicular to the first surface 22a. Similarly, in step 645, the second bent LB and the fourth return LB can be obtained from the fourth incident LB and the second reflected LB, respectively, using LFC 202 or an LFC with similar functionality.

[0136] According to some embodiments, method 600 may include an optional calibration step (not shown in Figure 6) similar to step 505 of method 500.

[0137] According to some embodiments, in steps 610 and 635, an autocollimator (e.g., an autocollimator) may be used to generate a plurality of pairs of parallel incident LBs. According to some embodiments, in steps 615, 620, 640, and 645, a return LB may be sensed using an autocollimator (e.g., an autocollimator used when preparing the incident LB). According to some embodiments, as essentially described in the description of Figures 2A and 2B, a shutter and / or spectral filter may be used to selectively block or partially block the second return LB and one of the first return LBs, as well as the fourth return LB and one of the third return LBs.

[0138] According to some embodiments, particularly those in which steps 610, 615, 620, 635, 640, and 645 are carried out using an autocollimator (such as autocollimator 240), in step 625, the first angular deviation of the second return LB relative to the first return LB

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[0139] At stage 655, the actual value of the inclination angle.

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[0140] For clarity, it should be understood that certain features of the Disclosure described in the context of separate embodiments may be provided in combination in a single embodiment. Conversely, for brevity, various features of the Disclosure described in the context of a single embodiment may be provided separately, in any suitable partial combination, or in a manner suitable for any other described embodiment of the Disclosure. Features described in the context of an embodiment should not be considered essential features of that embodiment unless specifically stated otherwise.

[0141] While the steps of the method in some embodiments may be described in a specific order, the method of this disclosure may include some or all of the described steps performed in a different order. The method of this disclosure may include some or all of the described steps. No particular step of the disclosed method should be considered an essential step of the method unless otherwise specified.

[0142] While this disclosure is described with regard to its specific embodiments, it is evident that a number of alternative, modified, and transformed forms may exist that are apparent to those skilled in the art. Therefore, this disclosure encompasses all such alternative, modified, and transformed forms that fall within the scope of the appended claims. It should be understood that this disclosure is not necessarily limited to the structure and arrangement of the components described herein and / or their application to the details of the methods. Other embodiments may be implemented, and embodiments may be performed in various ways.

[0143] The expressions and terms used herein are for illustrative purposes only and should not be construed as limiting. No reference or specification of any reference in this application should be construed as an admission that such reference is available as prior art to this disclosure. The headings used herein are for the purpose of facilitating the understanding of this specification and should not necessarily be construed as limiting.

Claims

1. An optical method for verifying the angle between flat surfaces on the outside of a sample, wherein the method is To provide a sample comprising an outer flat first surface and an outer flat second surface nominally inclined upward at a nominal inclination angle with respect to the first surface, To generate a first incident light beam (LB) directed to the first surface, and a second incident LB parallel to the first incident LB, Obtaining a first return LB by reflection of the first incident LB from the first surface, bending the second incident LB at an optical bending angle nominally equal to the nominal inclination angle, reflecting the bent LB from the second surface, and bending the reflected LB at the optical bending angle, thereby obtaining a second return LB. To measure the first angular deviation of the second return LB relative to the first return LB, An optical method comprising estimating the actual inclination angle of the second surface with respect to the first surface, at least based on the measured first angular deviation.

2. The optical method according to claim 1, wherein the first incident LB is directed perpendicularly to the first surface and onto the first surface.

3. The optical method according to claim 2, wherein the bending is performed using an optical fracting component (LFC), the LFC being a prism, one or more mirrors, and / or a diffraction grating, or comprising the same.

4. The optical method according to claim 3, wherein the optical bending angle is not affected by variations in the pitch of the LFC.

5. The optical method according to claim 4, wherein the LFC is a pentaprism or a prism with a similar function, or a pair of mirrors or a mirror device with a similar function set at a certain angle to each other, or includes the same.

6. The optical method according to any one of claims 1 to 3, wherein the sample is glass, polymer, metal, crystal, and / or a combination thereof, or comprises them.

7. The optical method according to claim 1, wherein the sample is a prism or a waveguide.

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

9. The optical method according to claim 1, wherein the first incident LB and the second incident LB are complementary portions of a single collimated LB.

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

11. The optical method according to claim 9, wherein the single collimated LB is polychromatic.

12. The optical method according to claim 10, wherein the single collimated LB is a laser beam.

13. The optical method according to claim 1, wherein the first angular deviation is measured using an autocollimator.

14. The optical method according to claim 13, wherein the measured first angular deviation between the return LBs is equal to or approximately equal to Δu / f, where Δu is the difference between the coordinates of the first spot and the corresponding coordinates of the second spot on the photosensitive surface of the autocollimator, and f is the focal length of the collimating lens of the autocollimator, the first spot being formed by the first return LB and the second spot being formed by the second return LB.

15. The optical method according to claim 1, further comprising an initial calibration step, in which an absolute reference sample is used to calibrate the system.

16. The nominal inclination angle is 90°, and the sample includes an outer flat third surface parallel to the first surface, the first incident LB is directed perpendicular to the first surface and onto the first surface, and the method follows the measurement of the first angular deviation, The sample is inverted to reverse the first and third surfaces while maintaining the nominal orientation of the second surface relative to the LFC, To prepare a third incident LB directed perpendicular to the third surface and directed toward the third surface, and a fourth incident LB parallel to the third incident LB, Obtaining a third return LB by reflection of the third incident LB from the third surface, bending the fourth incident LB at an optical bending angle nominally equal to the nominal inclination angle, obtaining a fourth return LB by reflection of the bent fourth incident LB from the second surface, and bending the reflected fourth incident LB at the optical bending angle, The method further includes measuring the second angular deviation of the fourth return LB relative to the third return LB, The optical method according to any one of claims 1 to 15, wherein, in estimating the actual inclination angle, the actual inclination angle is estimated by additionally taking into consideration the measured second angular deviation.

17. The optical method according to claim 16, wherein the uncertainty in the parallelism between the first surface and the third surface is smaller than the required measurement accuracy of the actual inclination angle.

18. The optical method according to claim 1, further comprising suppressing internal reflection from the fourth surface, provided that the sample includes an outer, flat fourth surface nominally parallel to the second surface.

19. An optical system for verifying the angle between flat surfaces on the outside of a sample, wherein the system is A light-bending component (LFC) nominally configured to bend incident light at the top at a nominal inclination angle defined by a first flat outer surface and a second flat outer surface of the sample, Illumination and collection equipment (ICA), A photogenerating assembly configured to (a) project a first incident light beam (LB) onto the first surface so as to generate a first return LB by reflection from the first surface, and (b) project a second incident LB onto the LFC parallel to the first incident LB so as to generate a second return LB by reflection from the LFC, the second surface, and bending due to reverse reflection through the LFC, An optical system comprising: an illumination and collection configuration including: at least one sensor configured to measure a first angular deviation of the second return LB relative to the first return LB, and / or an eyepiece assembly configured to allow manual measurement of the first angular deviation, wherein the measured first angular deviation indicates the actual inclination angle of the second surface relative to the first surface.

20. The optical system according to claim 19, wherein the first incident LB is configured to strike the first surface at a right angle.

21. The optical system according to claim 20, further comprising an orientation infrastructure configured to orient the sample such that the first incident LB strikes the first surface perpendicularly and / or the bent LB obtained by the bending of the second incident LB by the LFC strikes the second surface nominally perpendicularly.

22. The optical system according to claim 21, further comprising the at least one sensor and a calculation module configured to calculate the actual inclination angle of the second surface relative to the first surface based at least on the measured first angular deviation.

23. The optical system according to claim 22, wherein the ICA is an autocollimator or includes the autocollimator, the autocollimator includes the light source and the at least one sensor.

24. The optical system according to claim 23, further comprising a pair of blocking elements configured to enable the ICA to selectively block each of the first incident LB and the second incident LB.

25. The optical system according to claim 19, wherein the LFC includes a prism, a plane mirror, and / or a diffraction grating.

26. The optical system according to claim 19, wherein the optical bending angle of the LFC is not affected by variations in the pitch of the LFC.

27. The optical system according to claim 26, wherein the prism is a pentaprism or a prism with a similar function, or a pair of mirrors set at a certain angle to each other or a mirror device with a similar function.

28. The optical system according to claim 19, wherein the photogenerating assembly includes a light source and an optical instrument, the light source being configured to generate a single LB, and the optical instrument being configured to collimate the single LB.

29. The optical system according to claim 28, wherein the first incident LB and the second incident LB are complementary portions of the collimated LB.

30. The optical system according to claim 28, wherein the light source is a multicolor light source.

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

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

33. The optical system according to any one of claims 22 to 32, comprising the at least one sensor and the calculation module, wherein the nominal tilt angle is 90°, and the sample further includes an outer flat third surface parallel to the first surface, the calculation module is configured to calculate the actual tilt angle, taking into additional consideration a measured second angular deviation of a fourth return LB relative to a third return LB, and obtained by (a') projecting a third incident light beam onto the third surface of the sample so as to generate the third return LB by reflection from the third surface, and (b') projecting the fourth incident LB onto the LFC parallel to the third incident LB so as to generate a fourth return LB by reflection from the LFC, the second surface, and its bending due to reverse movement through the LFC.

34. The optical system according to claim 33, wherein the calculation module is further configured to calculate the uncertainty in the calculated value of the actual tilt angle, taking into account at least the manufacturing tolerances and imperfections of the LFC and the ICA.

35. The optical system according to claim 34, further comprising the orientation infrastructure, wherein the calculation module is configured to calculate the uncertainty in the calculated value of the actual tilt angle, taking into additional consideration the manufacturing tolerances and imperfections of the orientation infrastructure.

36. A method for producing a sample having a pair of outer flat surfaces set at a nominal angle to each other, wherein the method is: The stage of providing an unprocessed sample, The steps include processing the raw sample to obtain a processed sample having an outer flat first surface and an outer flat second surface set at a certain test angle with respect to the first surface, A step of measuring the test angle using the optical method described in any one of claims 1 to 18, If the test angle differs from the nominal angle by a predetermined difference, the processed sample is subjected to further processing to obtain a reprocessed sample. A method comprising the steps of measuring the difference between the test angle and the nominal angle of the reprocessed sample until the difference falls below a predetermined difference, and repeating the reprocessing step as necessary.

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