JP2000186910A - Optical displacement gauge - Google Patents

Abstract

PROBLEM TO BE SOLVED: To surely direct regular reflected light to be incident on the area of a light-receiving face, even if an optical displacement gauge is inclined slightly with respect to a measured object. SOLUTION: This triangulation type optical displacement gauge has a projection means 2 for irradiating a measured object 6 which is disposed in a slant direction to the measured object 6 having a surface, such as a mirror surface, a glossy surface, a glass surface, or the like; a projection lens 3 for condensing irradiation light 101 irradiated obliquely on the measured object 6 from the projection means 2; and a light-receiving means 4 for receiving regular reflected light 102 generated by regular reflection of the irradiation light 101 on the measured object 6. The optical displacement gauge measures the displacement of the measured object 6 by a light-receiving face 5 of the light-receiving means 4. A cylindrical lens 8 for making the regular reflected light 102 incident on an area of the light-receiving face 5 of the light-receiving means 4 is disposed between the measured object 6 and the light-receiving means 4.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a specular reflection type optical displacement meter based on a triangulation method, which measures the displacement of a measurement object by using regular reflection light from the object.

[0002]

2. Description of the Related Art A conventional triangulation optical displacement meter measures the displacement of an object to be measured having a surface such as a mirror surface, a glossy surface, or a glass surface using specular reflection light from the object. And a diffuse reflection type optical displacement meter that measures the displacement of an object to be measured that diffuses and reflects light on the surface by using diffusely reflected light from the surface of the object. As a first conventional example, a regular reflection type optical displacement meter is as shown in FIG. Reference numeral 11 denotes an optical displacement meter, and 2 denotes a light projecting means for irradiating irradiation light to the surface of the object to be measured from an oblique direction. Reference numeral 3 denotes a light projecting lens for projecting the irradiation light 101 of the light projecting means 2 to the measured object 6, which is a spherical lens, an aspherical lens, or a combination thereof. Reference numeral 4 denotes light receiving means for receiving the specularly reflected light 102 specularly reflected on the surface of the measured object 6, and is composed of, for example, a PSD (Position Detector) or a CCD. 5 is a light receiving surface on the light receiving means for detecting the incident position of light,
The shape is long in the horizontal direction on the paper (the direction in which the position can be detected),
It has a rectangular shape that is short in the direction perpendicular to the paper. Further, the light receiving surface 5 is disposed so as to be perpendicular to the regular reflection light 102 from the measured object 6. When the measured object 6 is located at the position 6a, the specular reflected light 102a from the measured object 6
The light enters the upper position 5a. Next, when the measured object 6 is displaced by the distance d and moves to the position 6b, the specularly reflected light 102b from the measured object 6 enters the position 5b on the light receiving surface 5. By detecting the change of the incident position on the light receiving surface 5 by the light receiving means 4 and performing signal processing by a signal processing circuit (not shown), the displacement amount of the measured object 6 can be measured. In FIG.
FIG. 1 shows a side view of a regular reflection type optical displacement meter. The light projecting means 2 and the light projecting lens 3 are not shown. Thus, the specularly reflected light 102 enters the light receiving surface 5 of the light receiving unit 4 in a state where the optical displacement meter 11 is installed perpendicular to the measured object 6. As a second conventional example, a diffuse reflection type optical displacement meter is as shown in FIG. Reference numeral 12 denotes an optical displacement meter, 2 denotes a light projecting means, 3 denotes a light projecting lens, 4 denotes a light receiving means, and a light projecting means for vertically irradiating irradiation light from the light projecting means 2 to the surface of the measured object 6. 2 and the light projecting lens 3 are arranged vertically toward the surface of the object 6 to be measured. Reference numeral 7 denotes an image forming lens provided between the measured object 6 and the light receiving means 4 for condensing a part of the diffusely reflected light diffusely reflected on the surface of the measured object 6 on a light receiving surface. A cylindrical lens 8 provided between the light receiving unit 4 and the light receiving unit 4 for condensing light in a direction perpendicular to the paper surface, bringing the light spot closer to a circle, and increasing the luminance. In such an optical displacement meter 12, when the measured object 6 is at the position 6a, the irradiation light 101 emitted from the light projecting means 2 is diffusely reflected on the surface of the measured object 6. A part 104a of the diffuse reflected light is condensed by the imaging lens 7, further condensed only in the direction perpendicular to the paper by the cylindrical lens 8, and is incident on the position 5a on the light receiving surface 5 of the light receiving means 4. Next, the measured object 6 is displaced by the distance d and the position 6
b, a portion 104b of the diffusely reflected light from the measured object 6 enters the position 5b on the light receiving surface 5. By detecting the change of the incident position on the light receiving surface 5 by the light receiving means 4, the displacement amount of the measured object 6 can be measured.

[0003]

However, in the first prior art, the configuration of the device is simpler than that of the diffuse reflection type. However, as shown in FIG. If it is slightly inclined with respect to 6, the regular reflection light 102 does not enter the light receiving surface 5 and the displacement of the measured object cannot be measured. Therefore, when installing the optical displacement meter, it is necessary to accurately install the optical displacement meter 11 so as not to be inclined with respect to the measured object 6, and it is very difficult to adjust the displacement meter installation. was there. Also, the second
According to the prior art, it is possible to easily adjust the displacement meter at the time of installation, and it is possible to measure the object where diffuse reflection occurs on the surface of the object to be measured, but for example, a mirror surface such as a silicon wafer used in semiconductor manufacturing, or a liquid crystal glass substrate. It is impossible to measure the displacement of an object to be measured having a glass surface as described above. In addition, since the light diffusely reflected by the object to be measured is diffused, an image forming lens is required for condensing light, which causes a problem that the configuration of the apparatus becomes complicated and the apparatus becomes expensive. Therefore, the present invention can reliably enter specularly reflected light into the area of the light receiving surface even if the optical displacement meter is slightly inclined with respect to the measured object, and has a simple and inexpensive structure. An object of the present invention is to provide an optical displacement meter.

[0004]

SUMMARY OF THE INVENTION In order to solve the above problems, the present invention provides a light projecting device which is provided in an inclined direction with respect to an object to be measured having a surface such as a mirror surface, a glossy surface or a glass surface and irradiates light. Means, a light projecting lens for condensing irradiation light emitted from the light projecting means in an oblique direction toward the object to be measured, and receiving regular reflection light obtained by regularly reflecting the irradiation light by the object to be measured. A light-receiving means, and a triangulation optical displacement meter for measuring the displacement of the object to be measured by a light-receiving surface of the light-receiving means, wherein the specularly reflected light is provided between the object to be measured and the light-receiving means. It is characterized in that a cylindrical lens is arranged so as to enter the area of the light receiving surface of the light receiving means. Further, the light receiving means comprises a position detecting element PSD or CCD. By the above means, even if the optical displacement meter is tilted,
The specularly reflected light from the object to be measured is refracted by the cylindrical lens and enters the light receiving surface. Therefore, installation adjustment of the optical displacement meter becomes easy. In addition, since it is an optical displacement meter of the specular reflection type to receive specularly reflected light from the measured object, it is not possible to measure the displacement of the measured object such as a mirror surface, glossy surface or glass surface of the measured object surface. It is possible. Further, an imaging lens for condensing specularly reflected light is not required, so that the configuration of the apparatus is simple and the apparatus is inexpensive.

[0005]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a front view of an optical displacement meter showing an embodiment of the present invention. In the drawings, the same components as those in the related art are denoted by the same reference numerals, and description thereof will be omitted. Only different points will be described. The configuration in which the present invention is different from the conventional one is as follows. That is, the cylindrical lens 8 is disposed between the measured object 6 and the light receiving unit 4 so that the specular reflected light 1
02 is made to enter the area of the light receiving surface 5 of the light receiving means 4. The light receiving surface 5 of the light receiving means 4 and the cylindrical lens 8 are arranged in parallel. With such a configuration, the measured object 6 is displaced by the distance d and the position 6
When moving from a to 6b, the specularly reflected light 102b from the measured object 6 enters the position 5b on the light receiving surface 5, and the light receiving means 4 detects a change in the incident position on the light receiving surface 5. FIG. 2 is a side view when the optical displacement meter 1 is inclined by the angle θ.
Reference numeral 101 denotes irradiation light emitted from the light projecting means 2 to the object 6 to be measured, 102 denotes specular reflected light regularly reflected on the surface of the measured object 6, and 103 denotes specular reflected light 102 by the cylindrical lens 8.
Is refracted light. When the optical displacement meter 1 is tilted by the angle θ as shown in the figure, the angle of the specularly reflected light 102 is doubled by 2θ. In FIG. 2, if there is no cylindrical lens 8, the specularly reflected light 1
02 cannot be incident, but by using the cylindrical lens 8, the regular reflected light 102 can be refracted by the cylindrical lens 8 and the refracted light 103 can be incident on the light receiving surface 5. In the optical displacement meter of the present invention, an imaging lens is not indispensable between the object to be measured and the light receiving means, but an imaging lens may be used if necessary.

[0006]

EXAMPLE An example in which an optical displacement meter was manufactured as one combination of the above-described embodiments and actually performed will be described. A semiconductor laser having a wavelength of 670 nm as the light projecting means 2,
An aspheric lens as the light projecting lens 3 and P as the light receiving means 4
SD was used. The light receiving surface 5 of the light receiving means 4 has a length of 3 mm in the direction in which the position can be detected and a length of 1 mm in the direction perpendicular to the paper. The light projecting means 2 is configured such that the distance between the frame of the optical displacement meter 1 and the measured object 6 is 30 mm, and both the incident angle 照射 1 of the irradiation light and the reflection angle ψ2 of the regular reflection light are 30 degrees.
The light projecting lens 3, the light receiving means 4, and the cylindrical lens 8 are arranged. FIG. 3 shows a block diagram of a signal processing circuit of the optical displacement meter. 100 is a PSD used as a light receiving means
And has one cathode C ₁ and two anodes A ₁ and A ₂ . A current I ₁ flowing between the cathode C ₁ and the anode A ₁ ,
It was converted by the voltage-V _1, V ₂ by the cathode C ₁ and the anode A ₂ between each current / voltage converter 101 and 102 the current I ₂ flowing through. Next, the voltages V ₁ and V ₂ are divided by a divider 1
03, the output signal Vout of the optical displacement meter was obtained by performing the following calculation. In _{Vout = (V 1 -V 2)} / (V 1 + V 2) an optical displacement meter having the above structure, the surface was measured displacement of the silicon wafer are mirror. Here, in order to examine the effects of the present invention, a cylindrical lens was removed from the configuration of the above embodiment, and a conventional regular reflection type optical displacement meter was manufactured. This conventional regular reflection type optical displacement meter has a capacity of 0.1 mm.
When tilted by 4 degrees or more, the specularly reflected light from the measured object deviated from the light receiving surface of the light receiving means, and the displacement could not be measured. On the other hand, the optical displacement meter used in the example of the present invention was able to measure the displacement up to a maximum inclination of 3 degrees. FIG. 4 shows an embodiment of the present invention, which is an output signal of an optical displacement meter. The horizontal axis represents the distance from the frame of the optical displacement meter to the object to be measured, and the vertical axis represents the output voltage of the optical displacement meter. It was taken. In the figure, the displacement measurement result when the optical displacement meter 1 is tilted twice is shown. The error of the output signal before and after the optical displacement meter 1 was tilted was 1 μm at maximum. Further, with the above optical displacement meter, the object to be measured was changed to glossy aluminum or transparent glass, and the displacement was measured. In both cases, the displacement could be measured until the optical displacement meter was tilted up to 3 degrees. From this, it was found that there was no problem in measuring the displacement of the object to be measured even if the optical displacement meter was inclined to some extent. Therefore, in the regular reflection type optical displacement meter, a cylindrical lens is arranged between the object to be measured and the light receiving means, so that the regular reflection light is made to enter the area of the light receiving surface of the light receiving means. Even if the optical displacement meter is tilted, the specularly reflected light from the measured object is refracted by the cylindrical lens and enters the light receiving surface, so that the installation and adjustment of the optical displacement meter becomes easy. In addition, because it is a regular reflection type optical displacement meter to receive regular reflection light from the measured object,
It is possible to measure the displacement of the object to be measured such that the surface of the object to be measured is a mirror surface, a glossy surface, a glass surface, or the like without any trouble. In addition, an imaging lens for condensing the specularly reflected light is not required, and the configuration of the apparatus is simple and the apparatus is inexpensive.

[0007]

As described above, according to the present invention, a specular reflection type optical displacement meter for receiving specularly reflected light from an object to be measured having a surface such as a mirror surface, a glossy surface, or a glass surface, Because the cylindrical lens is placed between the measured object and the light receiving means, even if the optical displacement meter is tilted,
Since the specularly reflected light from the object to be measured is refracted by the cylindrical lens and enters the light receiving surface, there is an effect that installation adjustment of the optical displacement meter is easy. Further, an imaging lens for condensing specularly reflected light is not required, so that the configuration of the apparatus is simple and the apparatus is inexpensive.

[Brief description of the drawings]

FIG. 1 is a front view of an optical displacement meter showing an embodiment of the present invention.

FIG. 2 is a side view of an optical displacement meter showing an embodiment of the present invention. .

FIG. 3 is a signal processing block diagram of an optical displacement meter showing an embodiment of the present invention.

FIG. 4 is an output signal of an optical displacement meter showing an embodiment of the present invention.

FIG. 5 is a front view of an optical displacement meter as a first conventional example.

FIG. 6 is a side view of an optical displacement meter as a first conventional example.

FIG. 7 is a front view of an optical displacement meter as a second conventional example.

FIG. 8 is a side view of an optical displacement meter showing a defect of the first conventional example.

[Explanation of symbols]

 1: Optical displacement meter 2: Light emitting means 3: Light emitting lens 4: Light receiving means 5: Light receiving surface 6: Object to be measured 8: Cylindrical lens 101: Irradiation light 102: Regular reflection light 103: Refraction light

Claims (2)

[Claims] 1. A light projecting means provided in a direction inclined with respect to a measured object having a surface such as a mirror surface, a glossy surface, or a glass surface, and irradiating light, and a light projecting means directed from the light projecting device to the measured object. A light projecting lens for condensing irradiation light irradiated in an oblique direction, and light receiving means for receiving regular reflection light in which the irradiation light is regularly reflected by the object to be measured, and a light receiving surface of the light receiving means In an optical displacement meter of a triangulation method for measuring a displacement of an object to be measured, between the object to be measured and the light receiving means, the specularly reflected light is made to enter a region of a light receiving surface of the light receiving means. An optical displacement meter comprising a cylindrical lens arranged therein. 2. The optical displacement meter according to claim 1, wherein said light receiving means comprises a position detecting element PSD or CCD.