JP2010026214A - Autofocus device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an autofocus device capable of favorably performing focusing without being affected by a work surface. <P>SOLUTION: In a hardness testing machine 100, a user is allowed to form an optional pattern to be projected on the surface of a sample S through the use of a pattern formation program 63a, then, the formed optional pattern is projected by a pattern projection program 63b, then, when the surface of the sample S on which the optional pattern is projected is captured as an image, a frequency analysis is performed by a spectral intensity calculation program 63c on the basis of the image to calculate the spectral intensity. Then, the sample S is moved by an AF(Z) stage 4 through the use of an autofocus program 63f, and in a position where the sample S is moved, it is determined whether the spectral intensity of the frequency component in the position separated at a prescribed distance from a DC component, calculated through the use of the spectral intensity calculation program 63c, is more than a prescribed value, and when being determined that the intensity is more than the prescribed value, focusing is performed at the very position. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an autofocus device.

  Conventional hardness testing machines that automatically focus an optical microscope include a laser focus method that uses a laser to focus, and a contrast that focuses by detecting the contrast of the sample surface using a CCD camera. The law is known.

  In the laser focus method described above, it is possible to focus even on a low-contrast device, but focusing is possible only at the point where the laser is hit. Further, the device itself is expensive, and the mechanism of the hardness tester becomes complicated by incorporating the device. On the other hand, in the contrast method, it is difficult to focus on a low contrast material such as a mirror surface or a glass surface.

Then, as an autofocus method that solves the problems of the laser focus method and contrast method described above, an arbitrary pattern that is imaged on the surface of the workpiece, called grid focus, is placed on the optical path of the illumination system, and the arbitrary pattern is measured. A method of performing autofocus processing by calculating an autofocus value by projecting onto a surface is known (see Patent Documents 1 and 2).
Japanese Patent Laid-Open No. 9-304685 JP 2004-29069 A

  However, in the case of the above prior art, for example, when a mark or scratch is formed on the workpiece surface, depending on the selection of the pattern projected on the workpiece surface, the autofocus calculated by the mark or scratch on the workpiece surface Value and the autofocus value calculated from the arbitrary pattern projected on the surface of the workpiece may be approximate values, in which case either autofocus value indicates the true focus position Therefore, there is a problem that a focus processing error occurs and the test equipment and measurement equipment having the autofocus processing function are stopped.

  SUMMARY OF THE INVENTION An object of the present invention is to provide an autofocus device that can suitably perform focusing without being affected by the work surface.

In order to solve the above problems, the invention described in claim 1
A light source for illuminating the sample surface;
Moving means for moving at least one of the sample or the objective lens along the optical axis of the objective lens;
Automatic focusing means for focusing the objective lens by moving at least one of the sample or the objective lens by the moving means;
In an autofocus device comprising:
Pattern creating means for creating an arbitrary pattern to be projected onto the sample surface;
Pattern projection means for projecting an arbitrary pattern created by the pattern creation means on the sample surface;
An imaging unit that images a sample surface on which an arbitrary pattern is projected by the pattern projection unit as an image;
From the image picked up by the image pickup means, performing a frequency analysis based on the frequency component, spectrum intensity calculation means for calculating the spectrum intensity for each frequency component,
With
The automatic focusing means includes
Each time at least one of the sample or the objective lens is moved by the moving means, the spectral intensity of the frequency component at a position away from the DC component calculated by the spectral intensity calculating means at the moved position. Determining means for determining whether or not is greater than a predetermined value;
When the determination means determines that the spectral intensity of the frequency component at a position away from the DC component by a predetermined distance exceeds a predetermined value, focusing is performed at the moved position.

  According to a second aspect of the present invention, in the autofocus device according to the first aspect, the frequency component at a position away from the DC component by a predetermined distance at any position moved by the moving unit by the determining unit. When it is not determined that the spectrum intensity exceeds a predetermined value, a message indicating that a pattern different from an arbitrary pattern projected on the sample surface is encouraged to be created by the pattern creating means is displayed on the predetermined display means. Display control means.

  According to a third aspect of the present invention, in the autofocus device according to the first or second aspect, the pattern creating means includes the pattern shape of the arbitrary pattern, the period of the arbitrary pattern, and / or the arbitrary pattern. It is characterized in that at least one of the direction angles can be specified.

According to the present invention, an arbitrary pattern to be projected onto the sample surface can be created by the pattern creating means. Then, when an arbitrary pattern is projected by the pattern projecting means, and the sample surface on which the arbitrary pattern is projected is imaged as an image, the frequency based on the frequency component is calculated by the spectrum intensity calculating means based on the image. Analysis is performed, and the spectrum intensity for each frequency component is calculated. Then, every time at least one of the sample or the objective lens is moved by the moving means by the automatic focusing means, the spectral intensity of the frequency component at a position away from the DC component by a predetermined distance is calculated by the spectral intensity calculating means. Whether or not the value is exceeded is determined by the determining means. When it is determined that the value is exceeded, the focus can be adjusted at the moved position.
Therefore, the user creates an arbitrary pattern so that any pattern does not overlap with the pull marks and scratches formed on the workpiece surface in advance, and based on the frequency analysis on the sample surface on which the arbitrary pattern is projected, Since the focus can be adjusted, a focus processing error can be surely prevented.
That is, it can be said that the autofocus device according to the present invention is an autofocus device that can perform focusing appropriately without being affected by the work surface.

Hereinafter, embodiments of the present invention will be described with reference to FIGS.
FIG. 1 is a perspective view showing an overall configuration of a hardness tester 100 as an autofocus device according to the present invention, and FIG. 2 is a schematic diagram showing a tester body 10 of the hardness tester 100. 3 is a schematic diagram showing the hardness measuring unit 1 of the testing machine body 10, FIG. 4 is a block diagram showing a configuration necessary for the main operation of the hardness testing machine 100, and FIG. (A) shows a state in which a striped stitch pattern is formed vertically on the surface of the sample S, and (b) shows a striped stitch pattern formed laterally on the surface of the sample S. FIG. 6 is a schematic diagram showing a state in which an arbitrary pattern is projected on the surface of the sample S. FIG. 6A is an oblique striped pattern on the stitch pattern of FIG. (B) shows an oblique stripe pattern projected on the pull pattern in FIG. 5 (b). FIG. 7 is a view showing a modified example of an arbitrary pattern according to the present invention. FIG. 7A shows a state in which an arbitrary pattern is rotated by a predetermined angle, and FIG. FIG. 8 shows a state in which a pattern having a wider interval than the pattern of a) is projected, FIG. 8 is a schematic diagram showing the result of frequency analysis performed on the surface of the sample S, and FIG. (B) is the spectral distribution of FIG. 6B, (c) is the spectral distribution on the AA 'line of (a), and (d) is the AA' line of (b). FIG. 9 is a flowchart regarding the automatic focusing method according to the present invention.
In addition, let the left-right direction of the testing machine main body 10 in FIG. 1 be an X direction, the front-back direction is a Y direction, and a height direction is a Z direction.

  For example, as shown in FIGS. 1 and 2, the hardness tester 100 includes a tester main body 10, and the tester main body 10 includes a hardness measurement unit 1, a sample stage 2 on which a sample S is placed, An XY stage 3 for moving the sample stage 2, an AF (Z) stage 4 for focusing on the surface of the sample S, and an elevating mechanism for raising and lowering the sample stage 2 (XY stage 3, AF (Z) stage 4) 5 etc. In addition, the hardness tester 100 includes a control unit 6, an operation unit 7, a monitor 8, and the like outside the tester main body 10.

  For example, as shown in FIG. 3, the hardness measurement unit 1 projects an illumination device 11 that illuminates the surface of the sample S, a CCD camera 12 that images the surface of the sample S, and an arbitrary pattern on the surface of the sample S. And a turret 16 that can be switched between the indenter shaft 14 and the objective lens 15 by rotating.

The illumination device 11 illuminates the surface of the sample S by irradiating light, and the light emitted from the illumination device 11 is a lens 1a, a lens 1b, a lens 1c, a half mirror 1d, a mirror 1e, and an objective lens. 15 to reach the surface of the sample S.
Thereby, the illumination 11 functions as a light source.

The CCD camera 12 has a predetermined imaging range on the surface of the sample S based on the reflected light from the surface of the sample S via the objective lens 15, the mirror 1e, the half mirror 1d, the lens 1f, the mirror 1g, and the lens 1h. The image data is acquired and output to the control unit 6 through the frame grabber 17 that can simultaneously store and store a plurality of frames of image data.
Further, when an arbitrary pattern is projected onto the surface of the sample S by execution of a pattern projection program 63b described later, the CCD camera 12 serves as an imaging unit that captures an image of the surface of the sample S on which the arbitrary pattern is projected. It is functioning.

The pattern projection unit 13 includes a liquid crystal panel 13a disposed between the lens 1b and the lens 1c, an LCD driver 13b that drives the liquid crystal panel 13a, and the like. The pattern projection unit 13 is connected to the control unit 6 and drives the liquid crystal panel 13a according to a control signal output from the control unit 6 to the LCD driver 13b to project an arbitrary pattern. Here, the “arbitrary pattern” is a fringe pattern, a concentric circle pattern, a lattice pattern, an oblique lattice pattern, or the like created by executing a pattern creation program 63a described later. The arbitrary pattern is not limited to these, and may be a plurality of triangular patterns, wavy patterns, or the like.
Thereby, the pattern projection part 13 functions as a pattern projection means.

  The indenter shaft 14 is moved toward the sample S placed on the sample stage 2 by a load mechanism unit (not shown) driven in accordance with a control signal output from the control unit 6, and an indenter 14 a provided at the distal end portion. Is pressed against the surface of the sample S with a predetermined test force.

The sample stage 2 has a sample fixing part 2 a that fixes the sample S to be placed on the sample stage 2.
The XY stage 3 is driven by a drive mechanism unit (not shown) that is driven in accordance with a control signal output from the control unit 6, and moves the sample stage 2 in a direction perpendicular to the moving direction of the indenter 14a. For example, when moving the indenter 14a so that the indenter shaft 14 provided in the vertical direction moves in the vertical direction, the sample stage 2 is moved in the horizontal direction (front and rear, left and right directions).
The AF (Z) stage 4 is driven according to a control signal output from the control unit 6, and finely raises and lowers the sample stage 2 based on the image data captured by the CCD camera 12 to focus on the surface of the sample S.
The elevating mechanism unit 5 is driven in accordance with a control signal output from the control unit 6 and moves the sample stage 2 (XY stage 3, AF (Z) stage 4) in the vertical direction.
The lifting mechanism 5 and the AF (Z) stage 4 constitute moving means.

The operation unit 7 includes a keyboard 71, a mouse 72, and the like, and performs operation input when performing a hardness test and operation input when creating an arbitrary pattern by executing a pattern creation program 63a described later. When a predetermined input operation is performed by the operation unit 7, a predetermined operation signal corresponding to the input operation is output to the control unit 6.
The operation unit 7 constitutes a pattern creating unit.

  The monitor 8 is constituted by a display device such as an LCD, for example, and the hardness test setting conditions input from the operation unit 7, the result of the hardness test, the surface of the sample S imaged by the CCD camera 12, and the eye mark. A pattern, an image of an arbitrary pattern, etc. are displayed. The monitor 8 functions as a display unit that displays a message when a display control program 63e described later is executed.

  As shown in FIG. 4, the control unit 6 includes a CPU (Central Processing Unit) 61, a RAM (Random Access Memory) 62, a storage unit 63, and the like, and a predetermined program stored in the storage unit 63 is executed. Thus, it has a function of performing operation control for performing a predetermined hardness test.

  The CPU 61 reads the processing program stored in the storage unit 63, develops it in the RAM 62, and executes it, thereby controlling the entire hardness tester 100.

  The RAM 62 develops the processing program executed by the CPU 61 in the program storage area in the RAM 62, and stores the input data and the processing result generated when the processing program is executed in the data storage area.

  The storage unit 63 includes, for example, a recording medium (not shown) in which programs, data, and the like are stored in advance, and this recording medium is configured by a semiconductor memory or the like. In addition, the storage unit 63 stores various data, various processing programs, data processed by executing these programs, and the like for the CPU 61 to realize the function of controlling the entire hardness tester 100. More specifically, as shown in FIG. 4, for example, the storage unit 63 stores a pattern creation program 63a, a pattern projection program 63b, a spectrum intensity calculation program 63c, a determination program 63d, a display control program 63e, and an automatic focusing program 63f. Etc. are stored.

The pattern creation program 63a is a program that causes the CPU 61 to realize a function of creating an arbitrary pattern to be projected onto the surface of the sample S.
Specifically, for example, as shown in FIG. 5A, an image in which a striped stitch pattern is formed in the vertical direction (Y direction) on the surface of the sample S is captured by the CCD camera 12. When displayed on the monitor 8, the CPU 61 executes the pattern creation program 63 a and projects an arbitrary pattern corresponding to the pull pattern projected onto the surface of the sample S by the pattern projection program 63 b described later to the user. You can make it through. In creating the above-mentioned arbitrary pattern, by operating the keyboard 71 and the mouse 72 of the operation unit 7, the shape of the arbitrary pattern (for example, striped, grid, concentric, inverted triangle, etc.), arbitrary The pattern period and / or the direction angle of an arbitrary pattern can be designated.
Therefore, for example, with respect to the vertical and horizontal stripe pattern as shown in FIGS. 6A and 6B, the pattern is a period in a direction inclined 45 degrees from the Y-direction axis. A striped pattern arranged at equal intervals, which is different from each other, or a pattern shown in FIG. 6A is rotated by a predetermined angle as shown in FIG. It is possible to easily create a striped pattern arranged at intervals, or to create a striped pattern having a wider interval than the pattern of FIG. 7A as shown in FIG. 7B.
The CPU 61 functions as a pattern creation unit together with the operation unit 7 by executing the pattern creation program 63a.

The pattern projection program 63b is a program that causes the CPU 61 to realize a function of projecting an arbitrary pattern created by executing the pattern creation program 63a onto the surface of the sample S.
Specifically, for example, the CPU 61 executes the pattern creation program 63a, the user operates the operation unit 7, and the shape and period of an arbitrary pattern projected on the surface of the sample S and / or the direction of the arbitrary pattern When a corner or the like is designated and input, the CPU 61 executes the pattern projection program 63b, transmits a control signal to the LCD driver 13b, and drives the liquid crystal panel 13a according to the control signal, as shown in FIG. In addition, the surface of the sample S is projected, and an arbitrary pattern is projected on the surface of the sample S.
The CPU 61 functions as a pattern projection unit together with the pattern projection unit 13 by executing the pattern projection program 63b.

The spectrum intensity calculation program 63c performs frequency analysis based on the frequency component from the image of the surface of the sample S on which an arbitrary pattern imaged by the CCD camera 12 is projected on the CPU 61, and calculates the spectrum intensity for each frequency component. It is a program that realizes the function to perform.
Specifically, the spectrum intensity is calculated as follows.

  For example, each time the AF (Z) stage 4 is driven to change the position of the sample S in the Z direction, a striped stitch pattern in the vertical direction (Y direction) is formed as shown in FIG. An image in which a striped pattern arranged at equal intervals in a direction inclined by 45 degrees from the Y-direction axis is projected on the surface of the sample S, or a horizontal direction (X A CCD camera 12 is an image obtained by projecting striped patterns arranged at equal intervals in a direction inclined by 45 degrees from the Y-direction axis on the surface of the sample S on which the striped stitch pattern of (direction) is formed. Is imaged. Then, the CPU 61 executes the spectrum intensity calculation program 63c, and executes a two-dimensional Fourier transform on the image for each position in the Z direction. As a result, for example, with respect to the surface of the sample S shown in FIG. 6A, the spectrum distribution based on the frequency component as shown in FIG. 8A shows the surface of the sample S shown in FIG. In contrast, a spectrum distribution based on frequency components as shown in FIG. 8B is generated. In FIGS. 8A and 8B, a portion displayed with a white circle schematically represents a portion with a low spectral intensity, and a portion displayed with a black circle schematically represents a portion with a high spectral intensity.

Lines AA ′ in FIGS. 8A and 8B are arbitrary patterns projected at this time (the pattern shown in FIG. 6A in FIG. 8A and the pattern shown in FIG. 8B in FIG. 8B). b) is a straight line in a direction orthogonal to the pattern), and the spectrum of the frequency components or DC components (DC components) of the points P0 and P0 ′, the points P1 and P1 ′ appearing on the line A-A ′. , The spectrum generated by projecting an arbitrary pattern.
On the other hand, the spectrum at the frequency components of the points Q0 and Q0 ′, the points Q1 and Q1 ′ not appearing on the line A-A ′ is a spectrum generated due to the catch pattern on the surface of the sample S. It can be seen that the spectrums in the frequency components of P0 and P0 ′ and points P1 and P1 ′ are generated in a spatially separated form.
That is, as shown in FIGS. 6A and 6B, since a striped pattern having a different direction from the pull pattern is projected as an arbitrary pattern, the spectrum generated due to the pull pattern and Spatial separation is possible.
Therefore, if attention is paid only to the spectrum for each spatial frequency generated on the line AA ′ in FIGS. 8A and 8B, an arbitrary pattern is projected as shown in FIGS. 8C and 8D. It is possible to calculate only the spectral intensity for each spatial frequency generated in (1).

Further, the point P0 and the point P0 ′ in FIG. 8A have a spectrum at a position farther from the center of the spectrum distribution (the midpoint of the line A-A ′) than the points Q0 and Q0 ′. The point P1 and the point P1 ′ in FIG. 8B also generate a spectrum at a position farther from the center of the spectrum distribution (the midpoint of the line AA ′) than the points Q1 and Q1 ′.
That is, as shown in FIGS. 6 (a) and 6 (b), as an arbitrary pattern, a striped pattern having a period different from the period of the stripe pattern is projected, so that an arbitrary pattern is projected. 8 can be separated from the spectrum generated due to the pulling pattern, which is advantageous in forming the spectral intensity distribution as shown in FIGS.

The determination program 63d causes the CPU 61 to determine whether or not the spectral intensity of the frequency component at a position away from the DC component by a predetermined distance exceeds a predetermined value based on the spectral intensity calculated by executing the spectral intensity calculation program 63c. It is a program that realizes the function.
Specifically, for example, when the spectral intensity for each spatial frequency (frequency component) as shown in FIG. 8C or FIG. 8D is calculated by executing the spectral intensity calculation program 63c of the CPU 61, The CPU 61 executes the determination program 63d, and the spectral intensities of frequency components (for example, points P0 and P0 ′ in FIG. 8C and points P1 and P1 ′ in FIG. 8D) at a position away from the DC component by a predetermined distance. Is greater than a predetermined value, that is, whether the value exceeds a predetermined peak value (for example, the spectrum intensity T value in FIGS. 8C and 8D).
That is, when the CPU 61 executes the determination program 63d, for example, when the spectrum intensity exceeds the T value as indicated by the points P1 and P1 ′ in FIG. 8D, the spectrum intensity is determined to exceed the predetermined value, and the spectrum intensity is determined. Based on the Z-direction position of the sample S at the time when is calculated, an automatic focusing program 63f, which will be described later, is executed to enable focusing.
On the other hand, even if the CPU 61 executes the determination program 63d to drive the AF (Z) stage 4 from the lower limit position to the upper limit position and change the position of the sample S in the Z direction, the spectrum intensity is calculated. When the spectrum intensity does not exceed the T value as in the points P0 and P0 ′ in FIG. 8C, it is determined that the spectrum intensity does not exceed the predetermined value, and the display control program 63e described later executes the display control program 63e. It is urged to create a pattern different from an arbitrary pattern projected on the surface of the sample S.
The CPU 61 functions as a determination unit by executing the determination program 63d.
It should be noted that a position that is a predetermined distance away from the DC component that causes a spectrum, such as the points P0 and P0 ′ in FIG. 8C or the points P1 and P1 ′ in FIG. 8D, is determined by the pattern projection program 63b. It is determined by an arbitrary pattern to be projected. Therefore, the position where the spectrum is generated according to the pattern shape, cycle, direction angle, etc. is stored in the storage unit 63 in advance, and the CPU 61 executes the pattern creation program 63a to create an arbitrary pattern by the user. The CPU 61 may read the position where the spectrum is generated from the storage unit 63 and calculate the position for determining the spectrum intensity in the determination program 63d.

The display control program 63e, when the CPU 61 has not determined by the determination program 63d that the spectral intensity of the frequency component at a position away from the DC component by a predetermined distance exceeds the predetermined value at any position in the Z direction of the sample S. And a program that realizes a function to display on the monitor 8 a message prompting the user to create a pattern different from an arbitrary pattern projected on the surface of the sample S.
Specifically, for example, the AF (Z) stage 4 is driven from the lower limit position to the upper limit position as indicated by points P0 and P0 ′ located at a predetermined distance in FIG. Even if the spectrum intensity is calculated each time the direction position is changed, if the spectrum intensity is determined not to exceed the predetermined value by the execution of the determination program 61d of the CPU 61, the CPU 61 executes the display control program 63e, A predetermined message is displayed on the monitor 8 to prompt the user to create a pattern different from the arbitrary pattern projected on the surface of S.
In other words, by performing the above display, the CPU 61 executes an automatic focusing program 63f, which will be described later, in a state where the spectral intensity does not exceed a predetermined value at any position in the Z direction of the sample S, and focusing of the sample S is performed. It is possible to avoid a situation where it becomes impossible (a focus processing error occurs).

The automatic focusing program 63f is used when the CPU 61 determines that the spectrum intensity of the frequency component at a position away from the DC component by the spectrum intensity calculation program 63c exceeds a predetermined value by the determination program 63d. , A program for realizing a function of performing focusing of the objective lens 15 at the position of the sample S in the Z direction.
Specifically, for example, when a spectrum intensity exceeding a T value such as the points P1 and P1 ′ located at a predetermined distance in FIG. 8D is calculated, the spectrum is determined by executing the determination program 61d of the CPU 61. Since it is determined that the intensity exceeds the predetermined value, the CPU 61 executes the display control program 63e, and performs focusing of the objective lens 15 based on the Z-direction position of the sample S for which the spectrum intensity is calculated.
The CPU 61 functions as an automatic focusing unit by executing the automatic focusing program 63f.

(About automatic focusing method)
Next, an automatic focusing method when a stitch pattern is formed on the surface of the sample S will be described with reference to the flowchart of FIG.
First, when the surface of the sample S picked up by the CCD camera 12 is displayed on the monitor 8 (step S1), the CPU 61 executes the pattern creation program 63a to give the user a pattern pattern formed on the surface of the sample S. A corresponding arbitrary pattern is created (step S2).
Next, the CPU 61 executes the pattern projection program 63b, drives the liquid crystal panel 13a, and projects the arbitrary pattern created in step S2 onto the surface of the sample S (step S3).

Next, the CPU 61 outputs a predetermined control signal, finely drives the AF (Z) stage 4, and moves the sample S in the Z direction (step S4).
Next, the CPU 61 determines whether or not the AF (Z) stage 4 has been driven from the lower limit position to the upper limit position (step S5).

  If it is determined in step S5 that the AF (Z) stage 4 has been driven from the lower limit position to the upper limit position (step S5; Yes), the CPU 61 executes the display control program 63e and is projected onto the surface of the current sample S. A message to prompt the creation of a pattern different from the arbitrary pattern being displayed is displayed on the monitor 8 (step S6), and the processes in and after step S2 are repeated.

On the other hand, if it is determined in step S5 that the AF (Z) stage 4 is not driven from the lower limit position to the upper limit position (step S5; No), the CPU 61 executes the spectrum intensity calculation program 63c, An image in which an arbitrary pattern is projected on the surface is picked up by the CCD camera 12, frequency analysis is performed on the image, and the spectrum intensity is calculated (step S7).
Next, the CPU 61 executes the determination program 63d, determines whether or not the spectral intensity of the frequency component at a position away from the DC component calculated in step S7 by a predetermined distance exceeds a predetermined value (step S8), and does not exceed it. In this case, the processes after step S4 are repeated (step S8; No).

  On the other hand, when it is determined in step S8 that the spectral intensity exceeds the predetermined value (step S8; Yes), the CPU 61 executes the automatic focusing program 63f, and the objective lens 15 at the position in the Z direction of the sample S at that time. Is performed (step S9).

Thus, according to the hardness tester 100 according to the present invention, an arbitrary pattern to be projected onto the surface of the sample S can be created by the pattern creation program 63a. Then, when the arbitrary pattern is projected by the pattern projection program 63b and the surface of the sample S on which the arbitrary pattern is projected by the CCD camera 12 is captured as an image, the spectrum intensity calculation program 63c based on the image. Frequency analysis based on the frequency component is performed, and the spectrum intensity for each frequency component is calculated. Then, each time the sample S is moved by the AF (Z) stage 4 by the automatic focusing program 63f, the spectrum of the frequency component at a position away from the predetermined distance calculated by the spectrum intensity calculation program 63c at the moved position. Whether or not the intensity exceeds a predetermined value is determined by the determination program 63d. When it is determined that the intensity exceeds the predetermined value, the focus can be adjusted at that position.
Therefore, the user creates an arbitrary pattern so that the patterns and scratches or scratches formed on the workpiece surface in advance do not overlap, and focuses on the sample surface on which the arbitrary pattern is projected. Since it can be adjusted, a focus processing error can be surely prevented.
That is, it can be said that the autofocus device according to the present invention is an autofocus device that can perform focusing appropriately without being affected by the work surface.

Further, according to the hardness tester 100 according to the present invention, the spectral intensity of the frequency component at a position separated by a predetermined distance from the DC component at any position moved by the AF (Z) stage 4 by the determination program 63d. If the display control program 63e determines that a pattern different from an arbitrary pattern projected on the surface of the sample S is urged to be created by the pattern creation program 63a when 8 can be displayed.
As a result, the spectral intensity of the frequency component at a position away from the DC component by a predetermined distance does not exceed a predetermined value, and it is possible to prevent a situation in which a focus processing error occurs by executing the automatic focusing program 63f. Become.

Further, according to the hardness tester 100 according to the present invention, an arbitrary pattern shape (for example, a striped shape) can be obtained by the pattern creation program 63a and when the user operates the keyboard 71 or the mouse 72 of the operation unit 7. , Lattice shape, concentric circle shape, inverted triangle shape, etc.), a period of an arbitrary pattern, and / or a direction angle of an arbitrary pattern, and the like.
As a result, even when various catch patterns are formed on the surface of the sample S, the user can create an optimum pattern for each catch pattern under creation conditions with a high degree of freedom. Is possible.

The present invention is not limited to the above embodiment. For example, the hardness tester can be used for a Vickers hardness tester, a Brinell hardness tester, a Knoop hardness tester, and the like.
Further, the present invention is not limited to a hardness tester. For example, an image measuring device, a microscope, or the like may be used as long as the autofocus device according to the present invention is used.
Further, a plurality of patterns projected by the pattern projection program 63b are stored in the storage unit 63 in advance, and at any position of the sample S moved by the AF (Z) stage 4 by the execution of the determination program 63d of the CPU 61. When it is not determined that the spectral intensity of the frequency component at a position away from the DC component exceeds a predetermined value, the CPU 61 selects a projection pattern stored in advance in the storage unit 63 in a predetermined order, An arbitrary pattern may be projected by the pattern projection program 63b.
Moreover, in the said embodiment, although the sample was moved by the raising / lowering mechanism part 5 and the AF (Z) stage 4 as a moving means, you may move the objective lens 15 side. In addition, the present invention can be freely changed and improved without departing from the gist of the invention.

It is a perspective view which shows the whole structure of the hardness tester based on this invention. It is a schematic diagram which shows the testing machine main body of the hardness testing machine which concerns on this invention. It is a schematic diagram which shows the hardness measurement part of the hardness tester which concerns on this invention. It is a block diagram which shows schematic structure of the hardness tester based on this invention. FIG. 2 is a schematic diagram of the surface of a sample in the hardness tester according to the present invention, where (a) shows a state in which a striped stitch pattern is formed in a vertical direction on the surface of the sample, and (b) shows a horizontal direction on the surface of the sample. It is a figure which shows the state in which the striped stitch pattern was formed. It is a schematic diagram which shows the state which projected the arbitrary pattern on the surface of the sample based on this invention, (a) is the state which projected the diagonal striped pattern on the pull pattern of Fig.5 (a), ( FIG. 5B is a diagram illustrating a state in which an oblique stripe pattern is projected on the stitch pattern of FIG. It is a figure which shows the modification of the arbitrary patterns which concern on this invention, (a) is the state which rotated the predetermined pattern by the predetermined angle, and (b) is a pattern with a space | interval wider than the pattern of (a) It is a figure which shows the state which projected. It is a schematic diagram which shows the result of having performed frequency analysis on the surface of the sample which concerns on this invention, (a) is the spectrum distribution of FIG. 6 (a), (b) is the spectrum distribution of FIG.6 (b), (C) is the figure which showed the spectrum distribution on the AA 'line of (a), (d) is the figure which showed the spectrum distribution on the AA' line of (b). It is a figure which shows the flowchart regarding the automatic focusing method which concerns on this invention.

Explanation of symbols

100 Hardness tester (autofocus device)
1 Hardness measurement unit 11 Illumination device (light source)
12 CCD camera (imaging means)
13a Liquid crystal panel (pattern projection means)
13b LCD driver (pattern projection means)
15 Objective lens 4 AF (Z) stage (moving means)
5 Lifting mechanism (moving means)
61 CPU (pattern creation means, pattern projection means, spectrum intensity calculation means, determination means, display control means, automatic focusing means)
63a Pattern creation program (pattern creation means)
63b Pattern projection program (pattern projection means)
63c Spectrum intensity calculation program (spectrum intensity calculation means)
63d Judgment program (judgment means)
63e Display control program (display control means)
63f Automatic focusing program (automatic focusing means)
7 Operation part (pattern creation means)
8 Monitor S Sample

Claims (3)

A light source for illuminating the sample surface;
Moving means for moving at least one of the sample or the objective lens along the optical axis of the objective lens;
Automatic focusing means for focusing the objective lens by moving at least one of the sample or the objective lens by the moving means;
In an autofocus device comprising:
Pattern creating means for creating an arbitrary pattern to be projected onto the sample surface;
Pattern projection means for projecting an arbitrary pattern created by the pattern creation means on the sample surface;
An imaging unit that images a sample surface on which an arbitrary pattern is projected by the pattern projection unit as an image;
From the image picked up by the image pickup means, performing a frequency analysis based on the frequency component, spectrum intensity calculation means for calculating the spectrum intensity for each frequency component,
With
The automatic focusing means includes
Each time at least one of the sample or the objective lens is moved by the moving means, the spectral intensity of the frequency component at a position away from the DC component calculated by the spectral intensity calculating means at the moved position. Determining means for determining whether or not is greater than a predetermined value;
An autofocus device characterized in that when the determination means determines that the spectral intensity of the frequency component at a position away from the DC component by a predetermined distance exceeds a predetermined value, focusing is performed at the moved position. The autofocus device according to claim 1, wherein
When the determination means does not determine that the spectral intensity of the frequency component at a position away from the DC component by a predetermined distance at any position moved by the moving means exceeds a predetermined value, An autofocus apparatus comprising: display control means for displaying on a predetermined display means that the pattern creation means prompts creation of a pattern different from the projected arbitrary pattern. The autofocus device according to claim 1 or 2,
The pattern creating means includes
An autofocus device, wherein at least one of a pattern shape of the arbitrary pattern, a period of the arbitrary pattern, and / or a direction angle of the arbitrary pattern can be designated.

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