Method for correcting a measuring device, a correction program for a measuring device, a measuring device, and a measuring system.

Abstract

This invention provides a method for correcting a measuring device by acquiring a profile without removing the reference surface from the device. [Solution] The correction method for the measuring device includes the following steps: a processor extracts the rotational component of the object to be measured, the rotational component of the object to be corrected, the concentric component of the object to be corrected, and the combined result of the concentric component of the object to be measured and the concentric component of the object to be measured; a processor extracts a profile of the concentric component of the object to be measured corresponding to the concentric component of the object to be corrected; a processor extracts the concentric component of the object to be measured based on a coordinate transformation profile obtained by coordinate transformation of the profile of the concentric component of the object to be measured corresponding to the concentric component of the object to be corrected; and a processor executes a correction map of the object to be corrected based on the combined result of the concentric component of the object to be corrected and the concentric component of the object to be measured, the concentric component of the object to be measured, and the rotational component of the object to be corrected.

Description

[[Technical Field]]

[0001] The present disclosure relates to a correction method for a measuring device, a correction program for a measuring device, a measuring device, and a measuring system. [[Background Art]]

[0002] Patent Document 1 discloses a technique aimed at providing a scanning interferometer that significantly reduces the load applied to the scanning mechanism and can easily measure a large-diameter test object. Patent Document 2 also discloses a technique aimed at providing an absolute calibration method and an absolute calibration apparatus capable of absolute calibration of a measurement wavefront for interferometric measurement of the shape of a surface to be measured.

[0003] A measuring device that performs interferometric measurement of the shape of a surface to be measured can ideally obtain a profile of a measurement object if the reference surface is completely flat. However, in reality, the reference surface also has undulations, and the interferometer obtains a measurement result that includes the undulations of the reference surface. If the profile of the reference surface is known in advance, the measuring device can subtract the profile of the reference surface from the measurement result to obtain a measurement result in the ideal state where the reference surface is completely flat.

[0004] As a method for creating a correction map, a method of removing the reference surface from the device and directly measuring it is known (Non-Patent Document 1). As another method for creating a correction map, a method for obtaining a planar map by combining a method for separating errors in rotational shapes, which is used in roundness measurement, and a radial shift method is also known (Non-Patent Document 2). [[Prior Art Documents]] [[Patent Documents]]

[0005] [[Patent Document 1]] Japanese Unexamined Patent Publication No. 05-133711 [[Patent Document 2]] Japanese Unexamined Patent Publication No. 10-221007 [[Non-Patent Documents]]

[0006] [Non-Patent Document 1] Toshiyuki Takatsuji, Yoichi Bito, Takamitsu Osawa, and Ryosuke Furuya, "An Absolute Flatness Calibration Algorithm Using the Three-Piece Combination Method," Transactions of the Japan Society for Precision Engineering, 2006, Vol. 72, No. 11, pp. 1368-1373. [Non-Patent Document 2] Shunji Ito, Teruhiko Hinachi, and Osamu Horiuchi, "High-Precision Measurement of Flatness Using the Two-Directional Method and the Radial Shift Method," Journal of the Japan Society for Precision Engineering, 1992, Vol. 58, No. 5, pp. 883-888. [Overview of the Initiative] [Problems that the invention aims to solve]

[0007] However, the method disclosed in Non-Patent Document 1 has the difficulty of requiring three identical optical flats to be prepared in order to obtain an absolute profile, and requiring them to be removed from the apparatus. Furthermore, the radial shift method disclosed in Non-Patent Document 2 narrows the range of the profile that can be obtained by the amount of movement.

[0008] This disclosure has been made in view of the above points, and aims to provide a method for correcting a measuring device, a correction program for a measuring device, a measuring device, and a measuring system that correct a measuring device by acquiring a profile without removing the reference surface from the device and without narrowing the range of profiles that can be acquired. [Means for solving the problem]

[0009] A correction method for a measuring device according to a first aspect of the present disclosure includes a first step in which a processor extracts, based on a first measurement result obtained by rotating the object to be measured, the rotational component of the object to be corrected, and a composite result of the concentric component of the object to be corrected and the concentric component of the object to be measured; a second step in which a profile of the concentric component of the object to be measured corresponding to the concentric component of the object to be corrected is obtained based on a second measurement result obtained by relatively displacing the object to be corrected and the object to be measured, the rotational component of the object to be measured, and the rotational component of the object to be corrected; a third step in which a concentric component of the object to be measured is obtained based on a coordinate transformation profile obtained by coordinate transformation of the profile of the concentric component of the object to be measured corresponding to the concentric component of the object to be corrected; and a fourth step in which a correction map of the object to be corrected is generated based on the composite result of the concentric component of the object to be corrected and the concentric component of the object to be measured, the concentric component of the object to be measured, and the rotational component of the object to be corrected.

[0010] A correction method for a measuring device according to a second aspect of the present disclosure is a correction method for a measuring device according to a first aspect, wherein the processor generates the correction map in the fourth step by subtracting the concentric component of the measurement target and adding the rotational component of the correction target from the combined result of the concentric component of the correction target and the concentric component of the measurement target.

[0011] A correction method for a measuring device according to a third aspect of this disclosure is a correction method for a measuring device according to a first aspect, wherein the processor displaces the measuring device in the range R≧r>R / 4, where the profile of the concentric components acquired in the second step passes through the center of the measuring device, R is the radius of the correction target, and r is the amount of displacement of the measuring device relative to the correction target.

[0012] A correction method for a measuring device according to a fourth aspect of this disclosure is a correction method for a measuring device according to a first aspect, wherein the processor obtains a second measurement result by averaging a plurality of measurement results obtained by displacing the object to be measured by a plurality of displacement amounts on the same plane in the second step.

[0013] A correction method for a measuring device according to a fifth aspect of this disclosure is a correction method for a measuring device according to a first aspect, wherein the processor obtains a second measurement result by averaging a plurality of measurement results obtained by displacing the object to be measured in a plurality of directions on the same plane in the second step.

[0014] A correction method for a measuring device according to a sixth aspect of the present disclosure is a correction method for a measuring device according to a first aspect, wherein the processor further performs a process that includes a fifth step of matching the correction map to the pixels of the measuring device.

[0015] A correction method for a measuring device according to a seventh aspect of this disclosure is a correction method for a measuring device according to a first aspect, wherein the measuring device is a device using an interferometer, and the object to be corrected is the reference plane of the interferometer.

[0016] A correction program for a measuring device according to the eighth aspect of this disclosure causes a computer to execute a process that includes: a first step of extracting the rotational component of the object to be measured, the rotational component of the object to be corrected, and a composite result of the concentric component of the object to be corrected and the concentric component of the object to be measured, based on a first measurement result obtained by rotating the object to be measured; a second step of obtaining a profile of the concentric component of the object to be measured corresponding to the concentric component of the object to be corrected, based on a second measurement result obtained by relatively displacing the object to be corrected and the object to be measured, the rotational component of the object to be measured, and the rotational component of the object to be corrected; a third step of obtaining the concentric component of the object to be measured based on a coordinate transformation profile obtained by coordinate transformation of the profile of the concentric component of the object to be measured corresponding to the concentric component of the object to be corrected; and a fourth step of generating a correction map of the object to be corrected, based on the composite result of the concentric component of the object to be corrected and the concentric component of the object to be measured, the concentric component of the object to be measured, and the rotational component of the object to be corrected.

[0017] A measuring device according to the ninth aspect of this disclosure comprises a measuring unit that optically measures a target to be measured, and a correction unit that corrects the measurement result of the measuring unit using a correction map generated by the correction method of the measuring device according to the first aspect of this disclosure.

[0018] A measurement system according to a tenth aspect of the present disclosure comprises: the measurement apparatus according to the ninth aspect of the present disclosure; a rotation stage that rotates the placed measurement object; and at least one movement stage that relatively displaces the measurement object with respect to a correction target.

Effects of the Invention

[0019] According to the present disclosure, there can be provided a correction method for a measurement apparatus, a correction program for a measurement apparatus, a measurement apparatus, and a measurement system that correct the measurement apparatus by acquiring a profile without removing a reference surface from the apparatus and without narrowing the range of acquirable profiles.

Brief Description of Drawings

[0020] [Figure 1] It is a diagram illustrating a schematic configuration of a measurement system according to an embodiment of the disclosed technology. [Figure 2] It is a block diagram illustrating a hardware configuration of a correction apparatus. [Figure 3] It is a block diagram illustrating an example functional configuration of a correction apparatus. [Figure 4] It is a diagram explaining undulation existing on an optical flat. [Figure 5] It is a diagram explaining separation of a rotational direction component between a measurement object side and a reference surface side. [Figure 6] It is a diagram illustrating an example of a measurement result in a state where the rotational direction component of the optical flat has disappeared. [Figure 7] It is a diagram illustrating an example of a measurement result in a state where the rotational direction components of the optical flat and the reference surface have disappeared. [Figure 8] It is a diagram illustrating an example of an extraction result of a rotational direction component of an optical flat. [Figure 9] It is a diagram illustrating an example of an extraction result of a rotational direction component of a reference surface. [Figure 10] It is a diagram explaining an example of a concentric circular component. [Figure 11]This figure shows the measurement being performed by displacing the optical flat in a certain axial direction. [Figure 12] This figure shows an example of measurement results obtained by displacing an optical flat in a certain axial direction. [Figure 13] This figure shows an example of a composite result of only the concentric components of the optical flat, obtained by subtracting the previously determined rotational component from the measurement results in Figure 12. [Figure 14] Figure 13 is a plan view of an example of the composite result of only the concentric components of the optical flat. [Figure 15] This graph extracts the dashed line portion of the composite result of only the concentric components of the optical flat shown in Figure 14. [Figure 16] This diagram illustrates profile conversion. [Figure 17] This graph shows an example of concentric component data for optical flats. [Figure 18] This figure shows an example of the concentric circular component of a reference surface, obtained by subtracting the concentric circular component of the optical flat from the combined data of the concentric circular components of the reference surface and the optical flat. [Figure 19] This figure shows an example of a correction map for a reference surface obtained by adding the rotational component of the reference surface to the concentric component of the reference surface. [Figure 20] This is a flowchart showing the flow of the correction process performed by the correction device. [Modes for carrying out the invention]

[0021] Hereinafter, an example of an embodiment of this disclosure will be described with reference to the drawings. In each drawing, identical or equivalent components and parts are given the same reference numerals. Also, the dimensional ratios in the drawings are exaggerated for illustrative purposes and may differ from the actual ratios.

[0022] Figure 1 shows a schematic configuration of the measurement system according to this embodiment. The measurement system 1 is a system that optically measures the shape of each part of a measurement target, such as an optical flat (or optical flat: Optical flat) 300, using a measurement device 200. The measurement system 1 also calibrates (or corrects) the measurement result of the measurement target 300 based on the shape of the reference surface 230 of the reference plate 225, which will be described later. The measurement device 200 is, for example, a Fizeau interferometer. Although the explanation assumes that the measurement device 200 is a Fizeau interferometer, the measurement device 200 can be any interferometer using a reference surface, such as a white light interferometer. A Fizeau interferometer is a type of laser interferometer. In the measuring device 200, laser light emitted from the laser 220 is made into parallel light by an interference optical system (not shown) equipped with a collimator lens, etc., is reflected by the reference surface 230 of the reference plate 225 and returns to the camera 210. At the same time, the laser light is irradiated onto the optical flat 300 through the reference surface 230, is reflected by the optical flat 300 and returns to the camera 210. Interference fringes are generated in the measuring device 200 due to the optical path difference between the reflected light from the reference surface 230 and the reflected light from the optical flat 300. The flatness of the optical flat 300 is measured by imaging these interference fringes with the camera 210. The camera 210, laser 220, and reference plate 225 are examples of the measuring unit in this disclosure.

[0023] This measurement system 1 includes a correction device 10 in addition to a measuring device 200. The measuring device 200 is configured to input and output data to and from the correction device 10. The correction device 10 is, for example, a personal computer (PC) and is a device that generates a profile (hereinafter sometimes referred to as a correction map) for correcting the reference plane 230. The measuring device 200 may be connected to the correction device 10 to send and receive data by a communication mechanism (not shown). The measuring device 200 may also input and output data to and from the correction device 10 via a storage medium or the like. The measuring device 200 may also have some or all of the functions of the correction device 10 described later. If some or all of the functions of the correction device 10 are provided in the measuring device 200, some or all of the functions of the correction device 10 provided in the measuring device 200 may not be present in the correction device 10.

[0024] The measurement system 1 has a stage 305 for adjusting the position of the optical flat 300. The stage 305 includes a uniaxial stage 310, a rotating stage 320, and a tilt stage 330. The uniaxial stage 310 displaces the optical flat 300 relative to the reference surface 230. The uniaxial stage 310 is an example of a moving stage in this disclosure. The rotating stage 320 rotates the optical flat 300 by a predetermined amount when measuring the optical flat 300. The rotating stage 320 is mounted on the uniaxial stage 310. As will be described later, in this embodiment, the correction device 10 generates a correction map of the reference surface 230 by using the measurement results measured by the measurement device 200 while the optical flat 300 is displaced relative to the reference surface 230. Displacing the optical flat 300 relative to the reference surface 230 means moving the optical flat 300 in a direction intersecting the optical axis of the laser beam, for example, in a perpendicular direction.

[0025] The tilt stage 330 maintains the optical flat 300 in a horizontal position, for example, during measurement of the optical flat 300. An XY swivel (gonio) stage may be used as the tilt stage 330. An XY swivel (gonio) stage is a type of rotary stage that allows for precise angle adjustment. This stage provides tilting motion around the X and Y axes, allowing the optical flat 300 to be adjusted by minute angles. Note that the tilt stage 330 does not necessarily have to be provided on the stage 305.

[0026] Figure 2 is a block diagram showing the hardware configuration of the correction device 10.

[0027] As shown in Figure 2, the correction device 10 includes a CPU (Central Processing Unit) 11, a ROM (Read Only Memory) 12, a RAM (Random Access Memory) 13, storage 14, an input unit 15, a display unit 16, and a communication interface (I / F) 17. Each component is connected to the others via a bus 19 so as to be able to communicate with each other.

[0028] The CPU 11 is a central processing unit that executes various programs and controls various parts. Specifically, the CPU 11 reads a program from the ROM 12 or storage 14 and executes the program using the RAM 13 as a working area. The CPU 11 controls each of the above components and performs various calculations according to the program recorded in the ROM 12 or storage 14. In this embodiment, the ROM 12 or storage 14 stores a correction program that generates a correction map for the reference surface 230 of the measuring device 200.

[0029] ROM12 stores various programs and data. RAM13 temporarily stores programs or data as a working area. Storage14 consists of a storage device such as an HDD (Hard Disk Drive), SSD (Solid State Drive), or flash memory, and stores various programs, including the operating system, and various data.

[0030] The input unit 15 includes a pointing device such as a mouse and a keyboard, and is used for various types of input.

[0031] The display unit 16 is, for example, a liquid crystal display and displays various information. The display unit 16 may also function as an input unit 15 by employing a touch panel system.

[0032] The communication interface 17 is an interface for communicating with other devices such as the measuring device 200, and standards such as Ethernet®, FDDI, and Wi-Fi® can be used.

[0033] When executing the above correction program, the correction device 10 uses the above hardware resources to implement various functions. The functional configuration implemented by the correction device 10 will now be described.

[0034] Figure 3 is a block diagram showing an example of the functional configuration of the correction device 10.

[0035] As shown in Figure 3, the correction device 10 has an acquisition unit 101, a profile generation unit 102, and a correction unit 103 as its functional configuration. Each functional configuration is realized by the CPU 11 reading and executing a correction program stored in the ROM 12 or storage 14.

[0036] The acquisition unit 101 acquires measurement results obtained by rotating the optical flat 300 with the rotating stage 320. The acquisition unit 101 acquires measurement results obtained by rotating the optical flat 300 using a method for separating rotational shape errors, such as the multi-step method. The multi-step method is a measurement method that separates rotational shape errors by repeatedly measuring while positioning the angular phase of a reference object (reference object) at equal angles, and numerically canceling out the shape errors of the reference object by calculating the average of multiple measurement values. The measurement results obtained by rotating the optical flat 300 with the multi-step method are an example of the first measurement results of this disclosure. The acquisition unit 101 also acquires measurement results when the optical flat 300 is displaced relative to the reference surface 230 with the uniaxial stage 310. The measurement results when the optical flat 300 is displaced relative to the reference surface 230 are an example of the second measurement results of this disclosure.

[0037] The profile generation unit 102 generates a profile (correction map) for correcting the reference surface 230 using the measurement results of the optical flat 300 acquired by the acquisition unit 101. The process by which the profile generation unit 102 generates the profile (correction map) for correcting the reference surface 230 will be described in detail later.

[0038] The correction unit 103 corrects the measurement results of the optical flat 300 using the correction map generated by the profile generation unit 102.

[0039] Furthermore, the measuring device 200 may, for example, have the function of a correction unit 103. That is, the measuring device 200 may be configured to correct the measurement result of the optical flat 300 in the correction unit 103 using a correction map of the reference surface 230 generated by the profile generation unit 102 of the correction device 10.

[0040] Next, the process of generating a correction map by the profile generation unit 102 will be described.

[0041] First, the profile generation unit 102 extracts the rotational component of the measurement target, the rotational component of the correction target, and the combined result of the concentric circle component of the correction target and the concentric circle component of the measurement target from the measurement results acquired by the acquisition unit 101. Here, the measurement target is the optical flat 300, and the correction target for which the correction map is generated is the reference surface 230. Furthermore, the rotational component is a component with non-rotationally symmetric characteristics, such as the non-rotationally symmetric component in Patent Document 2, and the concentric circle component is a component with rotationally symmetric characteristics, such as the rotationally symmetric component in Patent Document 2.

[0042] In this embodiment, the undulation present on the optical flat 300 is considered to be the result of a combination of a rotational component and a concentric component. Figure 4 is a diagram illustrating the undulation present on the optical flat 300. The rotational component is similar to the concept of the multi-step method of a roundness measuring machine, where the object being measured is rotated during measurement, allowing for the separation of the object being measured from the object being corrected. On the other hand, since the concentric component is at the same height on the same circumference, the multi-step method cannot separate the object being measured from the object being corrected. Therefore, in this embodiment, the measurement is performed by displacing the object being measured in the axial direction to separate the object being measured from the object being corrected for the concentric component. In this embodiment, the axial direction refers to the direction perpendicular to the optical axis of the laser beam and movable by the uniaxial stage 310.

[0043] Figure 5 illustrates the separation of the rotational component between the measurement target side and the reference surface side. During measurement with measurement system 1, the optical flat 300 is rotated by the rotation stage 320 using the multi-step method to obtain the measurement results. In this case, the rotation center of the optical flat 300 is aligned with the center of the reference surface 230. Figure 5 shows four examples of measurement results obtained by rotating by the rotation stage 320 in 90-degree increments. Note that the number of steps in the multi-step method is not limited to four, and more steps are desirable, but in this embodiment, for convenience, the number of steps is described as four. Hereinafter, the rotational component of the reference surface 230 will be referred to as "reference R", the concentric component of the reference surface 230 as "reference NR", the rotational component of the optical flat 300 as "work R", and the concentric component of the optical flat 300 as "work NR". The measurement results shown in Figure 5 are (Reference R + Reference NR) - (Work R + Work NR) ... (1) It is represented as follows.

[0044] Here, in the profile generation unit 102, the rotational component of the optical flat 300 is eliminated by averaging the measurement results of each step. That is, the rotational component of the optical flat 300 is eliminated by averaging the measurement results in the profile generation unit 102. (Reference R + Reference NR) - (Work NR) ... (2) This result is obtained. Therefore, by taking the difference between (1) and (2) in the profile generation unit 102, only the rotational component of the workpiece R, i.e., the optical flat 300, can be extracted.

[0045] Furthermore, in the profile generation unit 102, when the above (2) is rotated on the data and the results of each step are averaged, the rotational component of the reference surface 230 disappears. (Reference NR)-(Work NR) ···(3) This result is obtained. Therefore, in the profile generation unit 102, by taking the difference between (2) and (3), only the rotational component of the reference R, i.e., the reference surface 230, can be extracted.

[0046] Figure 6 shows an example of measurement results when the rotational component of the optical flat 300 described in (2) above has disappeared, and Figure 7 shows an example of measurement results when the rotational components of the optical flat 300 and the reference surface 230 described in (3) above have disappeared. Figure 8 shows an example of the extraction results of the rotational component of the optical flat 300, and Figure 9 shows an example of the extraction results of the rotational component of the reference surface 230.

[0047] Next, the profile generation unit 102 acquires a profile of the concentric circle component of the measurement target that corresponds to the concentric circle component to be corrected. In order to acquire a profile of the concentric circle component of the measurement target, the profile generation unit 102 separates the measurement target side and the reference surface side of the concentric circle component.

[0048] This section explains the separation of concentric components between the measurement target side and the reference surface side. To separate concentric components between the measurement target side and the reference surface side, it is sufficient to know the profile on one axis. This is because one rotation will yield data for the entire surface. Figure 10 illustrates an example of concentric components, showing that data for the entire surface can be obtained by rotating one concentric component once.

[0049] Therefore, in this embodiment, the measurement system 1 measures by displacing the optical flat 300 in a certain axial direction. The axial direction in which the optical flat 300 is displaced is not limited to one direction. By changing the direction of displacement by the uniaxial stage 310, and by providing multiple uniaxial stages 310 so that displacement can occur in multiple axial directions, the optical flat 300 can be displaced in multiple axial directions. Figure 11 shows the measurement of displacing the optical flat 300 in a certain axial direction. The profile generation unit 102 subtracts the rotational component obtained in advance from the measurement result, resulting in a result consisting only of the concentric circle component. When a cross section is extracted in a concentric shape that coincides with the center of the reference surface 230 (the center of the camera's field of view, the point at coordinates 0,0 in Figure 14), the height of the concentric circle component (reference NR) of the reference surface 230 is constant, so the profile generation unit 102 can obtain the profile of the concentric circle component (work NR) of the optical flat 300. Figure 12 shows an example of measurement results obtained by displacing the optical flat 300 in a certain axial direction. Figure 13 shows an example of a composite result of only the concentric components of the optical flat 300, obtained by subtracting the rotational component, which was determined in advance, from the measurement results in Figure 12. Figure 14 is a plan view of the example of the composite result of only the concentric components of the optical flat 300 shown in Figure 13, and Figure 15 is a graph that extracts the dashed line portion of the composite result of only the concentric components of the optical flat 300 shown in Figure 14.

[0050] Next, the profile generation unit 102 acquires the concentric components of the object to be measured based on the coordinate transformation profile obtained by coordinate transformation of the profile of the concentric components of the object to be measured. Specifically, the profile generation unit 102 first extracts in polar coordinate format the profile of a cross-section of a circle whose circumference passes through the center of the optical flat 300, which is the displacement amount when the center of the reference surface 230 (center of the measurement field of view) coincides with the center of the reference surface 230 and is measured with a displacement of the radius.

[0051] Next, the profile generation unit 102 converts the extracted profile into a profile on the radius of the optical flat 300. Figure 16 is a diagram illustrating the profile conversion. If the radius of the optical flat 300 is R and the displacement is r, the profile generation unit 102 can convert the extracted profile into a profile A on the radius of the optical flat 300 using the following equation (4). Figure 17 is a graph showing an example of concentric component data of the optical flat 300. The graph in Figure 17 is the graph after conversion from polar coordinates to XY coordinate values ​​(length on the radius).

[0052]

number

[0053] The profile generation unit 102 then rotates the converted profile 360 ​​degrees around the origin 0. This rotation of the converted profile around the origin 0 results in the concentric components (work NR) of the optical flat 300.

[0054] If the displacement amount r is within the range of R≧r>R / 4, the profile generation unit 102 can acquire the full-surface profile of the reference surface 230. In addition, the displacement amount r does not need to be within the range of R≧r>R / 4. It should be noted that when r<R / 4, data with a missing outer peripheral portion will be obtained, and when R<r, donut-shaped data will be obtained. There may be cases where the movement of the optical flat 300 by the uniaxial stage 310 is restricted due to reasons such as the measuring device 200 being provided with legs, but as long as sufficient data can be obtained, a smaller displacement amount r is preferable. The profile generation unit 102 averages data obtained by moving the optical flat 300 with a plurality of displacement amounts on the same plane, thereby obtaining a profile in which errors caused by movement errors (deviation between the actual displacement amount and the extraction position) and the like are reduced. In addition, when the optical flat 300 can be moved in a plurality of axial directions on a plane, the profile generation unit 102 may average data obtained by moving the optical flat 300 in a plurality of axial directions on the plane. By averaging data obtained by moving the optical flat 300 in a plurality of axial directions, a profile with higher accuracy can be obtained compared to the case where displacement is performed in one axial direction.

[0055] Subsequently, the profile generation unit 102 generates a correction map for the correction target based on a composite result of the concentric circular component of the correction target and the concentric circular component of the measurement target, the concentric circular component of the measurement target, and the rotational direction component of the correction target.

[0056] That is, since composite data of the concentric circular component of the reference surface 230 and the concentric circular component of the optical flat 300 is obtained in advance, the profile generation unit 102 can obtain the concentric circular component of the reference surface 230 by subtracting the concentric circular component of the optical flat 300 from this composite data. FIG. 18 is a diagram showing an example of the concentric circular component of the reference surface 230 obtained by subtracting the concentric circular component of the optical flat 300 from composite data of the concentric circular component of the reference surface 230 and the concentric circular component of the optical flat 300.

[0057] Since the rotational component of the reference surface 230 is obtained in advance, the profile generation unit 102 can generate a correction map of the reference surface 230 by adding the rotational component of the reference surface 230 to the concentric component of the reference surface 230. Figure 19 shows an example of a correction map of the reference surface 230 obtained by adding the rotational component of the reference surface 230 to the concentric component of the reference surface 230.

[0058] The profile generation unit 102 performs a series of processes to create a correction map for the reference surface 230 without removing the reference surface 230 from the measuring device 200, simply by displacing the optical flat 300 by a predetermined amount and performing measurements.

[0059] The resulting correction map may not match the pixel grid of the actual measurement device 200 because it has undergone rotation and other operations on the data. In such cases, the profile generation unit 102 may perform resampling and use pixel averaging, or perform fitting using a Zernike polynomial and use its order as the correction value.

[0060] Next, the operation of the correction device 10 will be explained.

[0061] Figure 20 is a flowchart showing the flow of the correction process performed by the correction device 10. The CPU 11 reads the correction program from the ROM 12 or storage 14, loads it into the RAM 13, and executes it, thereby performing the correction process.

[0062] In step S101, the CPU 11 extracts the rotational component of the object to be measured, the rotational component of the object to be corrected, and the combined result of the concentric circle component of the object to be corrected and the concentric circle component of the object to be measured. Here, the object to be measured is the optical flat 300, and the object to be corrected is the reference surface 230. The object to be corrected refers to the object for which the correction map is generated.

[0063] Following step S101, in step S102, the CPU 11 acquires a profile of the concentric component of the measurement target that corresponds to the concentric component to be corrected. In order to acquire a profile of the concentric component of the measurement target, the CPU 11 separates the measurement target side and the reference surface side of the concentric component.

[0064] Following step S102, in step S103, the CPU 11 acquires the concentric components of the object to be measured based on the coordinate transformation profile obtained by coordinate transformation of the profile of the concentric components of the object to be measured. Specifically, first the CPU 11 extracts in polar coordinate form the profile of the cross-section of a circle whose circumference passes through the center of the optical flat 300, where the center coordinates of the reference surface 230 (center of the measurement field of view) coincide with the center, and the displacement amount when the radius is displaced during measurement. Next, the CPU 11 converts the extracted profile into a profile of the circumference of the optical flat 300.

[0065] Following step S103, in step S104, the CPU 11 generates a correction map for the correction target based on the combined result of the concentric circle component to be corrected and the concentric circle component to be measured, the concentric circle component to be measured, and the rotational component to be corrected.

[0066] In other words, in step S101, composite data of the concentric components of the reference surface 230 and the optical flat 300 is obtained. Therefore, the CPU 11 can obtain the concentric component of the reference surface 230 by subtracting the concentric component of the optical flat 300 obtained in step S103 from this composite data. Furthermore, since the rotational component of the reference surface 230 is obtained in step S101, the CPU 11 can generate a correction map of the reference surface 230 by adding the rotational component of the reference surface 230 to the concentric component of the reference surface 230.

[0067] While embodiments of the present disclosure have been described in detail above with reference to the attached drawings, the technical scope of the present disclosure is not limited to these examples. It is clear that a person with ordinary skill in the art of the present disclosure may conceive of various modifications or alterations within the scope of the technical idea set forth in the claims, and these modifications or alterations are also understood to fall within the technical scope of the present disclosure.

[0068] For example, the above embodiments can be applied to measurement systems that include a measurement target having a non-planar reference surface and / or a surface under test, such as a sphere. Furthermore, although the above embodiments were described as measurement systems equipped with a measuring device having a reference surface, the above embodiments can also be applied to measurement systems equipped with a measuring device that does not have a reference surface. Even in the case of not having a reference surface, by applying the principles of the above embodiments, it is possible to separate the components originating from the measurement target from the components originating from the device, and thereby obtain a correction map as a strain component specific to the device. Therefore, the above embodiments can be applied to any device that can acquire a planar profile, such as a laser confocal microscope.

[0069] Furthermore, although the measurement system 1 shown in Figure 1 has an optical flat 300 installed below the measuring device 200, this disclosure is not limited to this example. The positional relationship between the measuring device 200 and the optical flat 300 is not limited to this example, as long as the configuration allows the laser light from the measuring device 200 to be reflected by the optical flat 300 and returned to the measuring device 200, and the reference surface 230 of the reference plate 225 and the optical flat 300 to be displaced relative to each other.

[0070] Furthermore, the effects described in the above embodiments are descriptive or illustrative, and are not limited to those described in the above embodiments. In other words, the technology relating to this disclosure may produce other effects that would be obvious to a person of ordinary skill in the art of this disclosure from the descriptions in the above embodiments, in addition to or in lieu of the effects described in the above embodiments.

[0071] In addition, the correction processing of the measuring device, which is executed by the CPU after reading the software (program) in each of the above embodiments, may be executed by various processors other than the CPU. Examples of such processors include PLDs (Programmable Logic Devices) such as FPGAs (Field-Programmable Gate Arrays) whose circuit configuration can be changed after manufacturing, and dedicated electrical circuits that are processors with circuit configurations specifically designed to execute specific processing, such as ASICs (Application Specific Integrated Circuits). Furthermore, the correction processing of the measuring device may be executed by one of these various processors, or by a combination of two or more processors of the same or different types (for example, multiple FPGAs, and a combination of a CPU and an FPGA). More specifically, the hardware structure of these various processors is an electrical circuit that combines circuit elements such as semiconductor elements.

[0072] Furthermore, while the above embodiments describe a configuration in which the correction processing program for the measuring device is pre-stored (installed) in ROM or storage, the invention is not limited thereto. The program may be provided in a form recorded on a non-transitory recording medium such as a CD-ROM (Compact Disk Read Only Memory), DVD-ROM (Digital Versatile Disk Read Only Memory), or USB (Universal Serial Bus) memory. The program may also be provided in a form that can be downloaded from an external device via a network. This disclosure may also be applied to program products. [Explanation of symbols]

[0073] 1. Measurement System 10 Correction device 200 measuring devices 210 Cameras 220 lasers 225 Reference plate 230 Reference plane 300 Optical Flat 305 Stages 310 Single-axis stage 320 rotation stage 330 Tilt Stage

Claims

1. The processor, A first step of extracting the rotational component of the object to be measured, the rotational component of the object to be corrected, and the combined result of the concentric circle component of the object to be corrected and the concentric circle component of the object to be measured, based on the first measurement result obtained by rotating the object to be measured. A second step of obtaining a profile of the concentric circle component of the measurement target corresponding to the concentric circle component of the correction target, based on the second measurement result obtained by relatively displacing the correction target and the measurement target, the rotational component of the measurement target and the rotational component of the correction target, A third step involves acquiring the concentric components of the measurement target based on a coordinate transformation profile obtained by coordinate transformation of the profile of the concentric components of the measurement target corresponding to the concentric components of the correction target, A fourth step of generating a correction map for the correction target based on the combined result of the concentric circle component of the correction target and the concentric circle component of the measurement target, the concentric circle component of the measurement target and the rotational direction component of the correction target, A method for correcting a measuring device, which involves performing a process that includes such a process.

2. The correction method for a measuring device according to claim 1, wherein the processor generates the correction map in the fourth step by subtracting the concentric component of the measurement target and adding the rotational component of the correction target from the combined result of the concentric component of the correction target and the concentric component of the measurement target.

3. The correction method for a measuring device according to claim 1, wherein the processor displaces the measuring device in the range R≧r>R / 4, where R is the radius of the correction target and r is the amount of displacement of the measuring device relative to the correction target.

4. The correction method for a measuring device according to claim 1, wherein the processor obtains a second measurement result by averaging a plurality of measurement results obtained by displacing the object to be measured by a plurality of displacement amounts on the same plane in the second step.

5. The correction method for a measuring device according to claim 1, wherein the processor obtains a second measurement result by averaging a plurality of measurement results obtained by displacing the object to be measured in a plurality of directions on the same plane in the second step.

6. The correction method for a measuring device according to claim 1, wherein the processor further performs a process that includes a fifth step of matching the correction map to the pixels of the measuring device.

7. The correction method for the measuring device according to claim 1, wherein the measuring device is a device using an interferometer, and the object to be corrected is the reference plane of the interferometer.

8. On the computer, A first step of extracting the rotational component of the object to be measured, the rotational component of the object to be corrected, and the combined result of the concentric circle component of the object to be corrected and the concentric circle component of the object to be measured, based on the first measurement result obtained by rotating the object to be measured. A second step of obtaining a profile of the concentric circle component of the measurement target corresponding to the concentric circle component of the correction target, based on the second measurement result obtained by relatively displacing the correction target and the measurement target, the rotational component of the measurement target and the rotational component of the correction target, A third step involves acquiring the concentric components of the measurement target based on a coordinate transformation profile obtained by coordinate transformation of the profile of the concentric components of the measurement target corresponding to the concentric components of the correction target, A fourth step of generating a correction map for the correction target based on the combined result of the concentric circle component of the correction target and the concentric circle component of the measurement target, the concentric circle component of the measurement target and the rotational direction component of the correction target, A calibration program for a measuring device that performs a process including the following.

9. A measuring unit that optically measures the object to be measured, A correction unit that corrects the measurement result of the measurement unit using the correction map generated by the correction method of the measuring device described in claim 1, A measuring device equipped with the following features.

10. The measuring device according to claim 9, A rotating stage for rotating the object to be measured, A moving stage that displaces the measurement target relative to the correction target, A measurement system equipped with the following features.

Images