JP2000074631A - Chamfered width measuring instrument - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a chamfered width measuring instrument which optically measures the chamfered width of a platy object to be measured, such as the optical quartz glass mask, etc., formed of a light transmitting material. SOLUTION: Illuminating lamps 2a-2d are arranged in such a way that the lamps 2a-2d are respectively faced oppositely to the sides of a mask M placed on the central part of a pedestal 1 and alternatively turned on and the light rays emitted from the turned on lamps 2a-2d are made incident to the mask M from one side edge section and irradiate the chamfered section of the mask M on the other side edge section. A CCD camera 8 which is moved by means of an X-Y driving mechanism 7 takes the picture of the irradiated chamfered section from a position right above the chamfered section. Then a picture processing means 11 binarizes the picture data taken by means of the camera 8 and an arithmetic processing section 12 calculates the width of the chamfered section from the binarized data.

Description

DETAILED DESCRIPTION OF THE INVENTION

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for optically measuring the width of a chamfered portion formed on each side of a flat object to be measured, for example, a mask made of quartz glass for optical use. The present invention relates to a chamfering width measuring device capable of performing the following.

[0002]

2. Description of the Related Art A flat plate formed of a light transmitting material,
For example, a quartz glass mask for optical use (hereinafter simply referred to as a “mask”) is generally formed in a flat plate shape and in a square shape. Then, in order to prevent chipping of the ridge portions that contact the side edges of the four sides of the mask and the upper and lower surfaces, a chamfering process for removing the ridge portions is generally performed. In such a mask, quality control is performed on each of the masks to measure, for example, dimensions such as the flatness, thickness, and four sides of the surface, as well as the width of the chamfered portion.

[0003]

When measuring the width of the chamfered portion provided on the mask, the width is often measured visually using a loupe with a scale or the like. Therefore, there is a problem that the measurement takes time and the productivity cannot be improved. In addition, the measurement work requires some familiarity, and furthermore, since the measurement is performed visually, the measurement accuracy is not constant, and there is a technical problem that the measurement accuracy is generally poor.

In recent years, the size of a mask has also been increased. Therefore, when it is desired to measure the chamfer width of each of the four sides of the mask, one side of the mask must be positioned on the mounting table of the mask. Each time, the mask is moved, or the measurer is forced to move along the four sides of the mask to perform measurement, and the measurement work is becoming more and more difficult. In addition, since the measurement is performed manually, problems such as attachment of dust and the like to the mask and damage to a part of the mask during the measurement may occur.

[0005] The present invention has been made in view of the above-mentioned problems, and the width of a chamfered portion formed on a flat plate formed of a light-transmitting material typified by the above-described mask is set to be non-uniform. An object of the present invention is to provide a chamfer width measuring apparatus capable of accurately and efficiently measuring in a contact state, and thereby to provide a chamfer width measuring apparatus capable of greatly improving productivity. It is intended for.

[0006]

According to the present invention, there is provided a chamfering width measuring apparatus according to the present invention, wherein at least one side edge is chamfered to form a flat plate formed of a light transmitting material. A chamfer width measuring device for optically measuring a chamfer width of a test object, wherein the test object mounting table on which the flat test object is mounted and the test object mounting table are mounted on the test object mounting table. Imaging means for imaging the chamfered portion formed on the object to be measured in a direction perpendicular to one surface of the object to be measured, and facing an imaging position of the object to be measured mounted on the object mounting table. Illuminating means for projecting light into the object from a side end of the object to be measured, image processing means for taking in image data obtained by the imaging means and binarizing the image data, and image processing Based on the binarized data processed by the means, And arithmetic processing means for calculating the chamfer width corresponding to the chamfered portion has been subjected to the measurement object is provided.

In this case, in a preferred embodiment, the flat object to be measured is formed in a square shape,
Four illuminations are arranged so as to face each side of the measured object in a state where the side end of each side is chamfered and the measured object is mounted on the measured object mounting table. Means, an illumination lighting control means for selectively lighting the four illumination means, and an XY driving means for changing an imaging position of the imaging means in synchronization with the control of the illumination lighting control means. Is done.

The illumination lighting control means selectively turns on each of the four illumination means sequentially, and sets the imaging position of the object to be measured which is opposite to the position of the illuminated illumination means. X- so that it is located at the side end
It is desirable that programming is performed so as to sequentially control the movement by the Y driving means. Further, it is preferable that the illumination means is constituted by a long illumination lamp extending along a length direction of a side end of each side of the object to be measured.

[0009] According to the chamfer width measuring apparatus configured as described above, the projection light from the illuminating means enters the object placed on the object placing table from the side end. Then, the side end opposite to the side end where the projection light is incident is imaged by the imaging means from the vertical direction. The image data obtained by the imaging means is binarized by the image processing means, and the chamfering width of the object at the imaging position is calculated by the arithmetic processing means based on the binarized data. This makes it possible to determine the chamfer width at a resolution corresponding to the density of pixels in, for example, a CCD image sensor used for the image pickup means.

In addition, four illuminating means for irradiating the projection light to each side of the rectangular object to be measured are arranged, and while the illuminating means is sequentially turned on, the imaging means is moved by the XY driving means. With such a configuration, it is possible to continuously measure the width of each chamfered portion applied to each side of the rectangular measurement object. This makes it possible to accurately and efficiently measure the width of each chamfer on each side of the measured object in a non-contact state. In this case, the illuminating means is selectively turned on only one lamp, interference with light incident on the DUT from other illuminating means,
Alternatively, it is possible to eliminate the influence of reflected light in the object to be measured by light incident on the object to be measured by another certifying means.
Therefore, it is possible to minimize the occurrence of errors in the image data in the case of binarization, and it is possible to further improve the measurement accuracy.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a chamfer width measuring apparatus according to the present invention will be described based on an embodiment shown in the drawings for measuring a chamfer width at a chamfered portion provided on a mask. FIG. 1 shows the entire configuration, and a DUT 1 having a flat disk shape and a rectangular shape is arranged such that the upper surface thereof is in a horizontal state. A stage on which a mask M as an object to be measured is mounted is formed at the center of the mounting table 1. This mask M is shown in FIG.
As shown in FIG. 2B, for example, the dimension in the vertical (A) direction is 450 mm, and the dimension in the horizontal (B) direction is 500 m.
m and a thickness (t) of about 9 mm. Then, as shown in FIG. 2 (c) showing the side end portion in an enlarged sectional view, a chamfered portion Mb is formed at a portion where the side end portion Ma of the mask M is in contact with both upper and lower surfaces.

As shown in FIG. 1, four illuminating lamps 2a to 2d as illuminating means are arranged so as to face each side of a mask M mounted on a center stage of the mounting table 1. That is, the mask M is mounted on the center stage of the mounting table 1 in a state surrounded by the four illumination lamps 2a to 2d. Each of the illumination lamps 2a to 2d has a long shape extending along the length direction of the side end of each side of the mask M as the object to be measured. Projection light can be made to enter the mask M almost uniformly from the side end of each side. In addition, each of the illumination lamps 2a to 2d may be formed in a substantially elongated shape by arranging a large number of point light sources in a straight line.

At both corners on the back side of the mounting table 1,
Each of the columns 3 is vertically set, and a rectangular column-shaped slide shaft 4 is horizontally arranged between upper ends of the columns 3. A slider 5 is axially slidably attached to the slide shaft 4 so as to surround the slide shaft 4. A support arm 6 slidable in a direction perpendicular to the slide shaft 4 is attached to the slider 5.
The slide shaft 4, the slider 5, and the support arm 6
Constitute the XY drive mechanism 7. At the front end of the support arm 6, on the upper surface of the mask M mounted on the mounting table 1, for example, a CCD camera 8 as an imaging means for imaging the mask M in a vertical direction is attached. .

The XY drive mechanism 7 is configured to be driven in the X-axis direction and the Y-axis direction by a stepping motor or a servomotor (not shown). Therefore, the CCD camera 8 scans along the chamfered portions Mb provided on the four sides of the mask M mounted on the mounting table 1 and can photograph the chamfered portions Mb from the upper surface in the vertical direction. The image data obtained by the CCD camera 8 is taken into an image processing means 11, and a well-known binarization process is executed in the image processing means 11. The binarized data processed by the image processing means 11 is supplied to an arithmetic processing means 12, where the chamfered portion Mb
Is calculated.

A command signal is supplied from the arithmetic processing means 12 to the illumination lighting control means 13. Control is performed so that 2d is alternatively turned on. The image processing means 11 includes:
A monitor 14 is connected so that the image captured by the CCD camera 8 can be appropriately monitored by the monitor 14. Further, a CRT 15 constituting data display means is connected to the arithmetic processing means 12.
2 to display data such as the chamfer width Mw. Although not shown in the figure, a printer may be further connected to the arithmetic processing unit 12 so that the data of the chamfer width Mw of each mask M or the like may be printed out as needed.

FIG. 3 shows the relationship between the measurement position of the chamfered portion of the mask M mounted on the mounting table 1 and the lighting state of each illumination lamp. That is, in the example shown in FIG. 3, only one illumination lamp 2a is turned on by the illumination lighting control means 13. In this case, the image pickup position F by the CCD camera 8 is XY such that it is located at the side end of the mask M facing the position where the illuminating lamp 2a is lit.
The driving means 7 is controlled. Each of the illuminating lamps 2a to 2d is controlled to be selectively lit by the illuminating lighting control means 13 as described above, whereas the imaging position F by the CCD camera 8 is set to any of the lit illuminating lights. X corresponds to the side end of the mask M facing the position of the lamp.
A sequence for controlling the Y driving means 7 is programmed.

FIG. 4 shows a CCD camera 8 in a state where one illumination lamp 2a is turned on as shown in FIG.
3 shows an image pickup state. As shown in the figure, the projection light from the illumination lamp 2a enters from one side end of the mask M and reaches the other side end where the CCD camera 8 is located directly above. At this time, the light incident into the mask M irradiates the other chamfer Mb, and a part of the irradiated light is transmitted upward in the chamfer Mb. FIG. 5 shows a state of an image screen obtained by the CCD camera 8. The example shown in FIG. 5 shows a case where the side end portion Ma and the chamfered portion Mb of the mask M are mirror-finished, and the other portions are sand-finished before the mirror-finish. The surface roughness of the sand-finished surface in this case is about 0.8 μm in center line average surface roughness: Ra.

The substantially central white portion shown in FIG.
The chamfer width Mw in the chamfer Mb is shown.
The double-hatched portion on the left side in the drawing corresponds to the outside of the side end of the mask M, and the imaging state of the CCD camera 8 is black. In addition, the single hatched portion on the right side in the drawing corresponds to a sand-finished portion on the upper surface of the mask M. Since this part is sand-finished, some light is projected on the upper part by diffuse reflection. However,
The image data in this portion is determined to be black when binarized. Therefore, the chamfered portions Mb formed on the four sides of the mask M are determined by the relationship between the binarized data of the CCD image sensor in the central white portion shown in FIG. 5 and the density of the pixels of the CCD image sensor. Can be calculated respectively.

As described above, by moving the CCD camera 8 to a predetermined position by driving the XY drive mechanism 7, the chamfer width of each part can be calculated and obtained. The acquired data is displayed by the CRT 15 constituting the data display means, and can be printed out by a printer (not shown) as necessary. Further, by driving the XY drive mechanism 7, for example, CC
By causing the D camera 8 to scan immediately above the chamfered portions provided on each of the four sides of the mask M, the respective chamfered widths can be continuously obtained over the entire circumference of the chamfered portion.

Although the above description has been made in accordance with the embodiment in which the width of the chamfered portion provided on each of the four sides of the mask is measured, the object to be measured is not limited to the specific one described above. It is possible to efficiently measure the width of a chamfered portion applied to another flat object formed of a light transmitting material.

[0021]

As is apparent from the above description, the chamfer width measuring apparatus according to the present invention comprises an image pickup means for picking up an image of one surface of an object to be measured from a direction perpendicular to the surface of the object to be measured, and Illuminating means for projecting light into the object to be measured from a side end of the object; binarizing image data obtained by the imaging means; and arranging the object data based on the binarized data. It is configured to calculate the chamfer width corresponding to the chamfered portion given in the above, so that the data of the chamfer width of the DUT can be efficiently acquired in a non-contact state. In addition, a configuration is provided in which four illuminating means for irradiating projection light on each side of the rectangular object to be measured are arranged, and while the illuminating means is sequentially turned on, the imaging means can be moved by the XY driving means. By doing so, it is also possible to continuously measure the width of each chamfered portion applied to each side of the rectangular object to be measured. Accordingly, the width of each chamfered portion on each side of the object to be measured can be accurately and efficiently measured in a non-contact state, and the productivity can be improved.

[Brief description of the drawings]

FIG. 1 is a perspective view showing an overall configuration of a chamfer width measuring apparatus according to the present invention.

FIG. 2 is a configuration diagram showing one form of a mask measured by the apparatus shown in FIG.

FIG. 3 is a schematic diagram showing a relationship between a measurement position of a chamfered portion of a mask performed in the apparatus shown in FIG. 1 and a lighting state of each illumination lamp.

FIG. 4 is a side view showing an image pickup state of the mask by the image pickup means in the state shown in FIG. 3;

FIG. 5 is a plan view showing a situation of a chamfered portion applied to a mask imaged by an imaging unit.

[Description of Signs] 1 DUT mounting table 2a to 2d Illumination means (illumination light) 3 Support 4 Slide shaft 5 Slider 6 Support arm 7 XY drive mechanism 8 Imaging means (CCD camera) 11 Image processing means 12 Arithmetic processing Means 13 Illumination lighting control means 14 Monitor 15 CRTF Image pickup position M Object to be measured (mask) Ma side end Mb Chamfer Mw Chamfer width

Claims (5)

[Claims] 1. A chamfer width measuring apparatus for optically measuring a chamfer width of a flat object to be measured formed of a light-transmitting substance having at least one side edge chamfered, An object mounting table on which the object is mounted, and an image of a chamfered portion provided on the object mounted on the object mounting table taken in a direction perpendicular to one surface of the object. An imaging unit that performs projection light into the object from a side end of the object facing an imaging position of the object placed on the object mounting table; Capture the image data obtained by the imaging means,
Image processing means for binarizing image data; and arithmetic processing means for calculating a chamfer width corresponding to a chamfered portion applied to the workpiece based on the binarized data processed by the image processing means. Equipped with a chamfer width measuring device. 2. A state in which the flat object to be measured is formed in a square shape, chamfering processing is performed on each side end of each side thereof, and the object to be measured is mounted on the object mounting table. , Four illuminating means arranged to face each side of the object to be measured, an illuminating control means for selectively illuminating the four illuminating means, and a control synchronized with the control of the illuminating controlling means. 2. The chamfer width measuring apparatus according to claim 1, further comprising: an XY driving unit that changes an imaging position of the imaging unit. 3. The illumination lighting control unit selectively turns on each of the four illumination units sequentially, and sets an imaging position of the object to be measured which is opposite to an arrangement position of the illuminated illumination unit. 3. The chamfer width measuring apparatus according to claim 2, wherein the XY driving means is programmed to sequentially control movement so as to be located at a side end. 4. The lighting device according to claim 1, wherein the illuminating means is configured by a long illuminating lamp extending along a length direction of a side end of each side of the object to be measured. The chamfer width measuring device as described. 5. The chamfer width measuring apparatus according to claim 1, wherein the object to be measured is an optical quartz glass mask. [0001]