Optical wedge angle calibration method and device and storage medium

Abstract

The invention discloses an optical wedge angle calibration method and device and a storage medium, and relates to the technical field of optical measurement. The optical wedge angle calibration method is used for carrying out wedge angle calibration on an optical wedge made of a single crystal material and comprises the steps that a scanning electron microscope is adopted to scan the geometric surface of the optical wedge to obtain a scanning image, a light intensity distribution diagram corresponding to the scanning image is extracted, each period of the light intensity distribution diagram corresponds to one lattice period of the surface, and the surface of the optical wedge is subjected to wedge angle calibration; tracing the dimension of the geometric surface to the microscopic lattice period dimension according to the quantitative relationship between the light intensity period and the pixel points, and then calculating the value of the wedge angle of the optical wedge according to the geometrical relationship of the surface measuring lines; the surface size of the optical wedge is calculated by the lattice period size, the lattice period size is calculated by the lattice constant according to the geometrical relationship of the monocrystalline silicon lattice, and the lattice constant of the monocrystalline material is a known quantity with extremely high precision, so that the optical wedge angle calibration method provided by the invention has extremely high precision.

Description

Technical Field

[0001] This invention relates to the field of optical measurement technology, and in particular to a method, apparatus and storage medium for calibrating the wedge angle of an optical wedge. Background Technology

[0002] An optical wedge, a widely used component in the field of optics, consists of two non-parallel optical working surfaces, with the included angle called the wedge angle. An optical wedge can deflect a light beam at a small angle, thereby changing the direction of light propagation and playing a crucial role in optical path guidance systems. A system composed of two optical wedges with the same refractive index and wedge angle can not only achieve the function of a single optical wedge but also be used for beam shaping and to achieve arbitrary angle deflection of light within a certain angular range. Based on these characteristics, optical wedges are widely used in many fields, including high-precision angle generators, optical path control for laser micro-hole processing, lidar systems, and testing systems for inter-satellite laser communication.

[0003] In the manufacturing process of optical wedges, accurate measurement of the wedge angle is a crucial step in ensuring the quality and performance of the wedge. Traditional methods for measuring the wedge angle mainly rely on the autocollimating telescope angle measurement method and the equal thickness interferometry method. The autocollimating telescope angle measurement method involves projecting a collimated beam from an autocollimating telescope at a near-perpendicular angle onto the optical wedge. The front and rear surfaces of the wedge reflect the collimated beam back to the autocollimating telescope, where they are imaged. Using the positional difference between these two images, combined with the focal length of the autocollimating telescope, the wedge angle value is calculated. This method essentially utilizes the principle of optical autocollimation. The measurement accuracy of the optical autocollimation principle is currently generally in the sub-microradian range (10⁻⁶). -7 The accuracy is on the order of rad, making further improvement difficult; the equal-thickness interferometry method uses a collimated laser beam to illuminate the optical wedge, utilizing the laser reflected from the front and rear surfaces of the wedge to form interference fringes. The wedge angle is calculated by measuring the spacing of the interference fringes. This method can achieve a measurement accuracy of tens of nanoradians (10). - 8 The accuracy is on the order of rad, but due to limitations in the measurement accuracy of interference fringe spacing and laser wavelength noise, it is difficult to further improve the accuracy. Summary of the Invention

[0004] This invention provides a method, apparatus, and storage medium for calibrating the wedge angle of an optical wedge, with the aim of calibrating the wedge angle of an optical wedge with high precision.

[0005] The optical wedge whose wedge angle is to be calibrated is made of single crystal material. The optical wedge includes a first optical working surface, a second optical working surface, a top surface, and a bottom surface. The top surface and the bottom surface are arranged in parallel. The first optical working surface and the second optical working surface are respectively connected to the opposite edges of the top surface and the bottom surface. The first optical working surface is perpendicular to the top surface and is not parallel to the second optical working surface.

[0006] The optical wedge angle calibration method provided by this invention includes the following steps:

[0007] S1, using a scanning electron microscope to scan the top and bottom surfaces along the x-axis to obtain scanned images; the x-axis is perpendicular to the first optical working surface;

[0008] S2, extract the light intensity distribution maps of the scanned images of the top and bottom surfaces in the x-axis direction, count the number of pixels corresponding to each period of the light intensity distribution maps of the top and bottom surfaces, and count the number of pixels contained in the scanned images of the top and bottom surfaces in the x-axis direction. Calculate the dimensions x1 of the top surface and x2 of the bottom surface in the x-axis direction according to the following formulas:

[0009] x1=N1·C1 / n1; x2=N2·C1 / n2;

[0010] In the formula, C1 represents the lattice period size of the top or bottom surface of the optical wedge; n1 and n2 represent the number of pixels corresponding to each period in the light intensity distribution map of the top and bottom surfaces of the optical wedge, respectively; and N1 and N2 represent the number of pixels contained in the scan image of the top and bottom surfaces of the optical wedge in the x-axis direction, respectively.

[0011] S3, obtain the dimension h of the first optical working surface in the z-axis direction; the z-axis is perpendicular to the top surface;

[0012] S4, calculate the wedge angle α of the optical wedge according to the following formula:

[0013] α = arctan(|x2-x1| / h).

[0014] Optionally, the optical wedge is made of monocrystalline silicon.

[0015] Optionally, the top and bottom surfaces are parallel to the {111} crystal plane of single-crystal silicon, and the lattice period size C1 = 0.314 nm of the top and bottom surfaces of the optical wedge.

[0016] Optionally, the dimension h of the first optical working surface in the z-axis direction is obtained through the following steps:

[0017] S31, A scanning electron microscope is used to scan the first optical working surface along the z-axis to obtain a scanned image;

[0018] S32, extract the light intensity distribution map of the scanned image of the first optical working surface in the z-axis direction, and count the number of pixels n corresponding to each period of the light intensity distribution map of the first optical working surface. h And count the number N pixels N contained in the scanned image of the first optical working surface in the z-axis direction. hThe dimension h of the first optical working surface in the z-axis direction is calculated according to the following formula:

[0019] h=N h ·C2 / n h ;

[0020] In the formula, C2 represents the lattice period size of the first optical working surface of the optical wedge.

[0021] Optionally, the dimension h of the first optical working surface in the z-axis direction is obtained by measuring an optical profilometer, an optical microscope, a laser interferometer, a laser scanning microscope, or an atomic force microscope.

[0022] Based on the above-described optical wedge angle calibration method, the present invention also provides an optical wedge angle calibration device, the device comprising:

[0023] A scanning electron microscope is configured to scan the surface of the optical wedge in a preset direction to acquire a scanned image.

[0024] The image processing module is configured to extract the light intensity distribution map of the scanned image in a preset direction;

[0025] The pixel statistics module is used to count the number of pixels corresponding to each period of the light intensity distribution map, and to count the number of pixels in the scanned image in the preset direction.

[0026] The calculation module is used to calculate the dimensions x1 of the top surface of the optical wedge in the x-axis direction and the dimensions x2 of the bottom surface of the optical wedge in the x-axis direction according to the following formula:

[0027] x1=N1·C1 / n1; x2=N2·C1 / n2;

[0028] In the formula, C1 represents the lattice period size of the top or bottom surface of the optical wedge; n1 and n2 represent the number of pixels corresponding to each period in the light intensity distribution map of the top and bottom surfaces of the optical wedge, respectively; and N1 and N2 represent the number of pixels contained in the scan image of the top and bottom surfaces of the optical wedge in the x-axis direction, respectively.

[0029] And, calculate the wedge angle α of the optical wedge according to the following formula:

[0030] α = arctan(|x2-x1| / h);

[0031] In the formula, h represents the dimension of the first optical working surface of the optical wedge in the z-axis direction.

[0032] Optionally, the calculation module calculates the dimension h of the first optical working surface in the z-axis direction according to the following formula:

[0033] h=N h ·C2 / n h ;

[0034] In the formula, C2 represents the lattice period size of the first optical working surface of the optical wedge, and n h N represents the number of pixels corresponding to each period of the light intensity distribution map of the first optical working surface of the optical wedge. h The number of pixels contained in the scanned image of the first optical working surface of the optical wedge in the z-axis direction.

[0035] Optionally, the optical wedge angle calibration device further includes an optical measurement module, which is used to measure the dimension h of the first optical working surface in the z-axis direction. The optical measurement module includes at least one of an optical profilometer, an optical microscope, a laser scanning microscope, and an atomic force microscope.

[0036] Optionally, the optical wedge angle calibration device also includes an error analysis module;

[0037] The error analysis module is used to calculate the calibration error of the wedge angle based on the error transfer function; the error transfer function is:

[0038] ;

[0039] In the formula, This indicates the wedge angle error value. This represents the error value of x1. This represents the error value of x2. This represents the error value of h.

[0040] The present invention also provides a computer storage medium storing a computer program, which, when executed by a processor, can implement the above-described optical wedge angle calibration method.

[0041] The present invention has the following beneficial effects:

[0042] On the geometric surface of a single-crystal optical wedge, atoms are arranged in a strictly ordered manner according to the lattice period, forming a periodic potential field distribution. A scanning electron microscope (SEM) scans the optical wedge surface with an incident electron beam. The interaction intensity between the incident electron beam and the optical wedge surface changes periodically with the periodic arrangement of the atoms. This is reflected in the light intensity distribution map as periodic peak-valley fluctuations through secondary electron imaging. Each fluctuation period corresponds to one lattice period on the optical wedge's geometric surface. This invention utilizes the high-resolution imaging advantage of the SEM to scan and image the geometric surface of the single-crystal optical wedge, extracting the light intensity distribution map. Based on the relationship between the light intensity period and the number of pixels, the dimensions of the geometric surface are traced back to the microscopic lattice period size. Then, the wedge angle value is calculated using the geometric relationship of surface measurement lines. The lattice period size of the single-crystal material is calculated from the lattice constant. Since the lattice constant of the single-crystal material is a known quantity with extremely high precision, the wedge angle value of the single-crystal optical wedge measured by the optical wedge angle calibration method provided by this invention has extremely high accuracy, with an error as low as 10⁻⁶. -10 It is on the order of radians, with an accuracy far exceeding that of traditional autocollimating telescope angle measurement and equal-thickness interferometry. Attached Figure Description

[0043] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0044] Figure 1 This is a flowchart of some embodiments of the optical wedge angle calibration method of the present invention;

[0045] Figure 2 This is a schematic diagram of the structure of the optical wedge to be tested in this invention;

[0046] Figure 3 This is a schematic diagram illustrating the principle of scanning the surface of the optical wedge using a scanning electron microscope according to the present invention;

[0047] Figure 4 This is a schematic diagram illustrating the test principle of some embodiments of the optical wedge angle calibration method of the present invention;

[0048] Figure 5 The images shown are scanning images of the surface of a single-crystal silicon optical wedge and corresponding light intensity distribution maps in the x-direction, obtained using a scanning electron microscope in some embodiments of the present invention.

[0049] Explanation of reference numerals in the attached diagram: 1. Top surface; 2. Bottom surface; 3. First optical working surface; 4. Second optical working surface. Detailed Implementation

[0050] To make the objectives, features, and advantages of this invention more apparent and understandable, the technical solutions of the embodiments of this invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the embodiments described below are only some embodiments of this invention, and not all embodiments. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0051] The terms “first,” “second,” “third,” “fourth,” etc. (if present) in the specification and drawings of this invention are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that embodiments of the invention described herein can be implemented, for example, in orders other than those illustrated or described herein. Furthermore, the terms “comprising” and “having,” and any variations thereof, are intended to cover a non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0052] See Figure 2 The optical wedge specified in this embodiment of the invention includes a first optical working surface 3, a second optical working surface 4, a top surface 1, and a bottom surface 2. The top surface 1 and the bottom surface 2 are arranged in parallel. The first optical working surface 3 and the second optical working surface 4 are respectively connected to the opposite edges of the top surface 1 and the bottom surface 2. The first optical working surface 3 is perpendicular to the top surface 1 and is not parallel to the second optical working surface 4. The included angle α between the first optical working surface 3 and the second optical working surface 4 is the wedge angle of the optical wedge.

[0053] It should be noted that before scanning and measuring the optical wedge, the oxide layer on the top and bottom surfaces of the optical wedge needs to be removed by grinding. The "top surface" and "bottom surface" mentioned in this embodiment refer to the top and bottom surfaces of the optical wedge after the oxide layer has been removed by grinding.

[0054] The optical wedge specified in this invention is made of a single-crystal material, including but not limited to single-crystal silicon, single-crystal germanium, single-crystal gallium arsenide, metallic single crystals, and ionic single crystals (such as calcium fluoride). The characteristic of single-crystal materials is that their atoms are highly ordered; on the geometric surface, atoms are arranged strictly according to the lattice period, and the lattice period size is calculated from the lattice constant, which is a known quantity with extremely high precision (for example, the lattice constant of single-crystal silicon is precisely calibrated by the International Union of Crystallography to be 0.5431 nm (25°C), with an error as low as 10). -8 (on the order of nm).

[0055] See Figure 3Scanning electron microscopy (SEM) uses an electron gun to emit an electron beam. This beam passes through converging, deflecting, and focusing coils to form an incident electron beam that irradiates the sample surface. The incident electron beam interacts with the atoms on the sample surface, exciting secondary electrons. The incident electron beam scans the sample surface in a specific spatial and temporal sequence. A secondary electron detector detects these secondary electrons and converts them into optical signals. An amplifier then converts the optical signals into electrical signals and amplifies them, ultimately displaying a scanned image on the monitor that reflects the surface morphology of the sample. Because secondary electrons are formed when electrons near the atomic nucleus break free from their nucleus under the influence of the incident electron beam, more secondary electrons are emitted from densely packed atomic sites (lattice sites), resulting in higher light intensity. Conversely, fewer secondary electrons are emitted from interstitial lattice sites, resulting in lower light intensity. For single-crystal samples, the atoms on the sample surface are arranged in a strictly periodic pattern. Therefore, the light intensity distribution in the scanned image changes periodically with the periodic arrangement of the atoms, with each fluctuation period corresponding to a lattice period on the optical wedge geometry. High-precision field emission scanning electron microscopes are preferred.

[0056] The optical wedge angle calibration method proposed in this invention combines the aforementioned characteristics of single-crystal materials and scanning electron microscopes, tracing the geometric dimensions of the optical wedge surface back to the microscopic lattice dimensions of the single-crystal material, thereby measuring the wedge angle of the optical wedge with high precision.

[0057] See Figure 1 and Figure 4 In some embodiments, the optical wedge angle calibration method provided by the present invention includes the following steps S1-S4:

[0058] S1, using a scanning electron microscope to scan the top and bottom surfaces along the x-axis to obtain scanned images; the x-axis is perpendicular to the first optical working surface.

[0059] Since the top and bottom surfaces of the optical wedge are parallel planes made of single-crystal material, they have the same lattice period size; scanning electron microscopy obtains scanning images of the top and bottom surfaces of the optical wedge through secondary electron imaging.

[0060] S2, extract the light intensity distribution maps of the top and bottom scan images along the x-axis, count the number of pixels corresponding to each period of the light intensity distribution maps of the top and bottom surfaces, and count the number of pixels contained in the top and bottom scan images along the x-axis. Calculate the dimensions x1 (length of measurement line 1) of the top surface and x2 (length of measurement line 3) of the bottom surface along the x-axis according to the following formulas:

[0061] x1=N1·C1 / n1; x2=N2·C1 / n2;

[0062] In the formula, C1 represents the lattice period size of the top or bottom surface of the optical wedge; n1 and n2 represent the number of pixels corresponding to each period in the light intensity distribution map of the top and bottom surfaces of the optical wedge, respectively; and N1 and N2 represent the number of pixels contained in the scanned images of the top and bottom surfaces of the optical wedge in the x-axis direction, respectively.

[0063] This step converts the dimensions of the top and bottom surfaces of the optical wedge into multiples of the lattice period size through the relationship between the number of pixels. The lattice period size C1 can be calculated from the lattice constant based on the mathematical and geometric relationship of the crystal structure of the single crystal material.

[0064] S3, obtain the dimension h (length of measurement line 2) of the first optical working surface in the z-axis direction; the z-axis is perpendicular to the top surface.

[0065] In some preferred embodiments, h can be measured using the same method as step S2 described above for measuring x1 and x2, specifically: S31, using a scanning electron microscope to scan the first optical working surface along the z-axis to obtain a scanned image; S32, extracting the light intensity distribution map of the scanned image of the first optical working surface along the z-axis, and counting the number of pixels n corresponding to each period of the light intensity distribution map of the first optical working surface. h And count the number N pixels N contained in the scanned image of the first optical working surface in the z-axis direction. h The dimension h of the first optical working surface in the z-axis direction is calculated according to the following formula:

[0066] h=N h ·C2 / n h ;

[0067] In the formula, C2 represents the lattice period size of the first optical working surface of the optical wedge, which can be calculated from the lattice constant based on the mathematical and geometric relationship of the crystal structure of the single crystal material.

[0068] In some other embodiments, since the h value of the optical wedge is much larger than x1 and x2 (several times or even more than ten times), it has little impact on the wedge angle calibration error. The value of h can also be measured by ordinary optical measurement methods, such as by measuring the value of h using equipment such as optical profilometers, optical microscopes, laser interferometers, laser scanning microscopes or atomic force microscopes.

[0069] S4. After obtaining the values ​​of x1, x2, and h, the wedge angle α of the optical wedge is calculated using the following formula based on the trapezoidal geometric relationship determined by x1, x2, and h:

[0070] α = arctan(|x2-x1| / h).

[0071] Because the atoms on the geometric surface of the single-crystal optical wedge are arranged in strict order according to the lattice period, a periodic potential field distribution is formed. When the scanning electron microscope scans the surface of the optical wedge with the incident electron beam, the interaction intensity between the incident electron beam and the surface of the optical wedge changes periodically with the periodic arrangement of the atoms. This is reflected as periodic peak-valley fluctuations in the light intensity distribution map through secondary electron imaging. Each fluctuation period corresponds to one lattice period of the optical wedge's geometric surface.

[0072] This invention utilizes the high-resolution imaging advantage of scanning electron microscopy to scan and image the geometric surface of a single-crystal optical wedge, extracting the light intensity distribution map. Based on the relationship between the light intensity period and the number of pixels, the size of the geometric surface is traced back to the microscopic lattice period size. Then, the wedge angle value of the optical wedge is calculated through geometric relationships. The lattice period size of the single-crystal material is calculated from the lattice constant. Since the lattice constant of the single-crystal material is a known quantity with extremely high precision, the wedge angle value of the single-crystal optical wedge measured by the optical wedge angle calibration method provided by this invention has extremely high accuracy.

[0073] Based on the above embodiments, in order to better illustrate the implementation process and beneficial effects of the technical solution of the present invention, the present invention also proposes the following specific embodiments. It should be noted that the following specific embodiments are merely exemplary and are not intended to limit the scope of protection of the present invention in any way.

[0074] Example 1

[0075] Step 1: Fabricate an optical wedge using single-crystal silicon material. The single-crystal silicon crystal has a face-centered cubic diamond structure with a lattice constant of 0.5431 nm (25℃). The top and bottom faces of the optical wedge are parallel to the {111} crystal plane of the single-crystal silicon, forming an equilateral triangular close-packed structure. The lattice period of the top and bottom faces is... .

[0076] Step 2: Place the optical wedge with its top surface facing upwards on the sample stage of the scanning electron microscope. Scan the top surface of the optical wedge along the x-axis to obtain a two-dimensional scanning image, such as... Figure 5 As shown.

[0077] Step 3: Extract the light intensity distribution map of the two-dimensional scanned image of the top surface of the light wedge, such as... Figure 5 As shown, the light intensity distribution curve is a peak-valley curve that fluctuates periodically along the scanning direction. Each period of the light intensity distribution curve corresponds to a lattice period C1 of single-crystal silicon on the {111} crystal plane.

[0078] Step 4: Count the number of pixels n1 corresponding to each cycle in the light intensity distribution map of the top surface. Then the pixel spacing size of the two-dimensional scanning image of the top surface is C1 / n1. Count the total number of pixels N1 contained in the two-dimensional scanning image of the top surface in the x-axis direction. Then the size of the top surface of the light wedge in the x-axis direction is x1=N1·C1 / n1.

[0079] Step 5: Place the bottom surface of the optical wedge and the first optical working surface horizontally upwards on the sample stage of the scanning electron microscope. Repeat steps 2-4 to calculate the dimension of the bottom surface in the x-axis direction x2=N2·C1 / n2 and the dimension of the first optical working surface in the z-axis direction h=N h ·C2 / n h .

[0080] Step 6: x1, x2, and h form a trapezoidal geometric relationship. Calculate the wedge angle α = arctan(|x2-x1| / h) based on the trapezoidal geometric relationship.

[0081] The error propagation function for the trapezoidal geometric relationship is:

[0082] ;

[0083] In the formula, This indicates the wedge angle error value. This represents the error value of x1. This represents the error value of x2. This represents the error value of h.

[0084] Taking the lattice period size C1 = 0.314 nm of the top or bottom surface of single-crystal silicon as an example, the resolution of commonly used scanning electron microscopes is on the order of 1 nm. Based on the scanning electron microscope image, the dimension x1 = 5 mm of the top surface of the optical wedge along the x-axis is obtained. Its error value... =0.03nm (because the dimensions x1 and x2 are obtained by combining scanning electron microscope images with the silicon lattice period dimensions, the error value is set according to 1 / 10 of the silicon lattice period dimensions, which is taken as 0.03nm. This ratio is easy to achieve in the precision measurement scheme of this application, and the error value of x2 is similar); the dimension x2 in the x-axis direction of the bottom surface is 5mm + 50nm, and its error value is... =0.03nm; the dimension h of the first optical working surface in the z-axis direction is 5cm, and its error value is... =50nm (h dimension can be obtained using measurement methods such as laser interferometer, with the error value calculated as 10% of the actual dimension). -6 (The setting, this ratio is easily implemented in the precision measurement scheme of this application); the calculated wedge angle α = 1 × 10⁻⁶ is obtained. -6 rad, calculate its error value based on the error transfer function. =8.5×10 -10rad; As can be seen from the above embodiments, the wedge angle calibration method provided by the present invention can achieve a wedge angle error as low as 10 rad. -10 It is on the order of radians, and its calibration accuracy is far superior to that of traditional autocollimating telescope angle measurement methods and equal thickness interferometry methods.

[0085] Based on the above-described optical wedge angle calibration method, the present invention also provides an optical wedge angle calibration device.

[0086] In some embodiments, the optical wedge angle device includes a scanning electron microscope, an image processing module, a pixel statistics module, and a calculation module.

[0087] The scanning electron microscope is configured to scan the surface of the optical wedge in a preset direction to obtain a scanned image.

[0088] The image processing module is configured to extract the light intensity distribution map of the scanned image in a preset direction.

[0089] The pixel statistics module is used to count the number of pixels corresponding to each period of the light intensity distribution map, and to count the number of pixels in the scanned image in a preset direction.

[0090] The calculation module is used to calculate the dimensions x1 of the top surface of the optical wedge in the x-axis direction and the dimensions x2 of the bottom surface of the optical wedge in the x-axis direction according to the following formula:

[0091] x1=N1·C1 / n1; x2=N2·C1 / n2;

[0092] In the formula, C1 represents the lattice period size of the top or bottom surface of the optical wedge; n1 and n2 represent the number of pixels corresponding to each period in the light intensity distribution map of the top and bottom surfaces of the optical wedge, respectively; and N1 and N2 represent the number of pixels contained in the scan image of the top and bottom surfaces of the optical wedge in the x-axis direction, respectively.

[0093] And, calculate the wedge angle α of the optical wedge according to the following formula:

[0094] α = arctan(|x2-x1| / h);

[0095] In the formula, h represents the dimension of the first optical working surface of the optical wedge in the z-axis direction.

[0096] In some preferred embodiments, the calculation module also calculates the dimension h of the first optical working surface in the z-axis direction according to the following formula:

[0097] h=N h ·C2 / n h ;

[0098] In the formula, C2 represents the lattice period size of the first optical working surface of the optical wedge, and n hN represents the number of pixels corresponding to each period of the light intensity distribution map of the first optical working surface of the optical wedge. h The number of pixels contained in the scanned image of the first optical working surface of the optical wedge in the z-axis direction.

[0099] In some other embodiments, the optical wedge angle calibration device further includes an optical measurement module for measuring the dimension h of the first optical working surface in the z-axis direction. The optical measurement module includes at least one of an optical profilometer, an optical microscope, a laser scanning microscope, and an atomic force microscope.

[0100] In some embodiments, the optical wedge angle calibration device further includes an error analysis module; the error analysis module is used to calculate the calibration error of the optical wedge angle according to the error transfer function; the error transfer function is:

[0101] ;

[0102] In the formula, This indicates the wedge angle error value. This represents the error value of x1. This represents the error value of x2. This represents the error value of h.

[0103] The present invention also provides a computer storage medium storing a computer program, which, when executed by a processor, can implement the above-described optical wedge angle calibration method.

[0104] In the several embodiments provided by this invention, it should be understood that the disclosed apparatus and methods can be implemented in other ways. For example, the apparatus embodiments described above are merely illustrative. For instance, the division of units / modules is only a logical functional division, and in actual implementation, there may be other division methods. For example, multiple units / modules or components may be combined or integrated into another system, or some features may be ignored or not executed. Furthermore, the coupling or direct coupling or communication connection shown or discussed may be through some interfaces; the indirect coupling or communication connection of the apparatus or units / modules may be electrical, mechanical, or other forms.

[0105] The units / modules described as separate components may or may not be physically separate. The components shown as units / modules may or may not be physical units / modules; that is, they may be located in one place or distributed across multiple network units / modules. Some or all of the units / modules can be selected to achieve the purpose of this embodiment according to actual needs.

[0106] Furthermore, in the various embodiments of the present invention, the functional units / modules can be integrated into one processing unit / module, or each unit / module can exist physically separately, or two or more units / modules can be integrated into one unit / module. The integrated unit / module described above can be implemented in hardware or in the form of software functional units / modules.

[0107] If the integrated unit / module is implemented as a software functional unit / module and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present invention, in essence, or the part that contributes to the prior art, or all or part of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions for executing all or part of the steps of the methods described in the various embodiments of the present invention through a computer device (which may be a personal computer, server, or network device, etc.). The aforementioned storage medium includes: USB flash drives, portable hard drives, read-only memory (ROM), random access memory (RAM), magnetic disks, optical disks, and other media capable of storing program code.

[0108] The above-described embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for calibrating the wedge angle of an optical wedge, wherein the optical wedge is made of a single-crystal material, the optical wedge includes a first optical working surface, a second optical working surface, a top surface, and a bottom surface, the top surface and the bottom surface being arranged parallel to each other, the first optical working surface and the second optical working surface respectively connecting the opposite edges of the top surface and the bottom surface, the first optical working surface being perpendicular to the top surface and not parallel to the second optical working surface, characterized in that... The method includes the following steps: S1, using a scanning electron microscope to scan the top and bottom surfaces along the x-axis to obtain scanned images; the x-axis is perpendicular to the first optical working surface; S2, extract the light intensity distribution maps of the scanned images of the top and bottom surfaces in the x-axis direction, count the number of pixels corresponding to each period of the light intensity distribution maps of the top and bottom surfaces, and count the number of pixels contained in the scanned images of the top and bottom surfaces in the x-axis direction. Calculate the dimensions x1 of the top surface and x2 of the bottom surface in the x-axis direction according to the following formulas: x1=N1·C1 / n1; x2=N2·C1 / n2; In the formula, C1 represents the lattice period size of the top or bottom surface of the optical wedge; n1 and n2 represent the number of pixels corresponding to each period in the light intensity distribution map of the top and bottom surfaces of the optical wedge, respectively; and N1 and N2 represent the number of pixels contained in the scan image of the top and bottom surfaces of the optical wedge in the x-axis direction, respectively. S3, obtain the dimension h of the first optical working surface in the z-axis direction; the z-axis is perpendicular to the top surface; S4, calculate the wedge angle α of the optical wedge according to the following formula: α = arctan(|x2-x1| / h).

2. The method for calibrating the wedge angle of an optical wedge according to claim 1, characterized in that, The optical wedge is made of monocrystalline silicon.

3. The method for calibrating the wedge angle of an optical wedge according to claim 2, characterized in that, The top and bottom surfaces are parallel to the {111} crystal plane of monocrystalline silicon.

4. The method for calibrating the wedge angle of an optical wedge according to claim 1, characterized in that, The dimension h of the first optical working surface in the z-axis direction is obtained through the following steps: S31, A scanning electron microscope is used to scan the first optical working surface along the z-axis to obtain a scanned image; S32, extract the light intensity distribution diagram of the scanning image of the first optical working surface in the z-axis direction, and count the number n of pixel points corresponding to each period of the light intensity distribution diagram of the first optical working surface h , and count the number N of pixel points contained in the scanning image of the first optical working surface in the z-axis direction h ; calculate the size h of the first optical working surface in the z-axis direction according to the following formula: h=N h ·C2 / n h ; In the formula, C2 represents the lattice period size of the first optical working surface of the optical wedge.

5. The method for calibrating the wedge angle of an optical wedge according to claim 1, characterized in that, The dimension h of the first optical working surface in the z-axis direction is obtained by measuring an optical profilometer, an optical microscope, a laser interferometer, a laser scanning microscope, or an atomic force microscope.

6. A wedge angle calibration device for calibrating the wedge angle of an optical wedge, wherein the optical wedge is made of a single crystal material, the optical wedge includes a first optical working surface, a second optical working surface, a top surface, and a bottom surface, the top surface and the bottom surface are arranged parallel to each other, the first optical working surface and the second optical working surface are respectively connected to the opposite edges of the top surface and the bottom surface, the first optical working surface is perpendicular to the top surface and not parallel to the second optical working surface, characterized in that... The device includes: A scanning electron microscope is configured to scan the surface of the optical wedge in a preset direction to acquire a scanned image. The image processing module is configured to extract the light intensity distribution map of the scanned image in the preset direction; The pixel statistics module is used to count the number of pixels corresponding to each period of the light intensity distribution map, and to count the number of pixels in the scanned image in the preset direction. The calculation module is used to calculate the dimensions x1 of the top surface of the optical wedge in the x-axis direction and the dimensions x2 of the bottom surface of the optical wedge in the x-axis direction according to the following formula: x1=N1·C1 / n1; x2=N2·C1 / n2; In the formula, C1 represents the lattice period size of the top or bottom surface of the optical wedge; n1 and n2 represent the number of pixels corresponding to each period in the light intensity distribution map of the top and bottom surfaces of the optical wedge, respectively; and N1 and N2 represent the number of pixels contained in the scan image of the top and bottom surfaces of the optical wedge in the x-axis direction, respectively. And, calculate the wedge angle α of the optical wedge according to the following formula: α = arctan(|x2-x1| / h); In the formula, h represents the dimension of the first optical working surface of the optical wedge in the z-axis direction.

7. The optical wedge angle calibration device according to claim 6, characterized in that, The calculation module calculates the dimension h of the first optical working surface in the z-axis direction according to the following formula: h=N h ·C2 / n h ; In the formula, C2 represents the lattice period size of the first optical working surface of the optical wedge, and n h N represents the number of pixels corresponding to each period of the light intensity distribution map of the first optical working surface of the optical wedge. h The number of pixels contained in the scanned image of the first optical working surface of the optical wedge in the z-axis direction.

8. The optical wedge angle calibration device according to claim 6, characterized in that, It also includes an optical measurement module, which is used to measure the dimension h of the first optical working surface in the z-axis direction. The optical measurement module includes at least one of an optical profilometer, an optical microscope, a laser scanning microscope, and an atomic force microscope.

9. The optical wedge angle calibration device according to claim 6, characterized in that, It also includes an error analysis module; The error analysis module is used to calculate the calibration error of the wedge angle based on the error transfer function; the error transfer function is: ； In the formula, This represents the error value of the wedge angle α. This represents the error value of x1. This represents the error value of x2. This represents the error value of h.

10. A computer storage medium, characterized in that, The device contains a computer program that, when executed by a processor, implements the optical wedge angle calibration method according to any one of claims 1-5.

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