JPS622113A - Surface roughness meter using reflected light - Google Patents

Abstract

PURPOSE:To enable the detection of mirror reflected light and scattered light irrelevant to the direction of convexes and concaves of an object to be measured even with steak-like convexes and concaves, by arranging a specified halfmirror and a light shielding plate having circular slits in the optical axis. CONSTITUTION:A halfmirror 6 and a light shielding plate 7 having circular slit 8 are arranged in the optical path of the reflected lights from an object 4 to be measured. In operation, the mirror reflected light among the reflected light is reflected with the halfmirror 6 to be introduced to a detector 2 which only the scattered light passing through the slit 8 are focused with a condenser lens 9 to be introduced to a detector 3 and then, the roughness is determined from the ratio between the detectors 2 and 3. Thus, the light beams in the same scattered light are allowed to pass through the slit 8 even when an optical system turns on the axis 20 thereby enabling the detection of the quantity of light received with the detectors 2 and 3 constantly irrelevant to the direction of convexes and concaves of an object 4 being measured even with stripe-form convexes and concaves.

Description

Detailed Description of the Invention (a) Technical Field of the Invention This invention illuminates an object to be measured with light from a light source, detects specularly reflected light and scattered light from the object, and detects the surface of the object. The present invention relates to a surface roughness meter that is capable of detecting scattered light regardless of the direction of the unevenness even when measuring the roughness of an object having streak-like unevenness on the measurement surface.

(b) Prior art and problems A surface roughness meter using reflected light measures the surface roughness of the object by irradiating the object with light from a light source and detecting the reflected light from the object. . In this case, as measurement parameters, the light intensity of the specularly reflected light and the scattered light intensity in a certain specific direction of reflection are determined, and these are compared to measure the surface roughness of the object to be measured.

A configuration diagram of the prior art in such a case is shown in FIG.

In FIG. 2, 1 is a light source, 2 and 3 are detectors, and 4 is an object to be measured.

In FIG. 2, light from a light source 1 is irradiated onto an object to be measured 4 at an incident angle θ, and specularly reflected light from the object to be measured 4 is reflected at an angle of reflection e. Detector 2 detects specularly reflected light having a reflection angle θ.

The object to be measured 4 generates scattered light other than specularly reflected light depending on the roughness of the surface.

The detector 3 is for detecting scattered light at a specific reflection angle other than specularly reflected light.

The measurement surface of the object to be measured 4 usually has streak-like unevenness corresponding to the machining direction of the tool. When the object to be measured 4 is irradiated with light from the light source, the reflected and scattered light from the object to be measured 4 spreads in a direction perpendicular to the direction of the unevenness, as shown in FIG.

When the distribution of reflected and scattered light as shown in FIG. 3 is measured using a surface roughness meter as shown in FIG. 2, there is a problem that the intensity of the scattered light detected by the detector 3 varies depending on the direction of the unevenness.

FIG. 4 shows the pattern of scattered light and the detection state depending on the position of the detector 3 in the case as shown in FIG.

In order to eliminate such problems, when the light from the light source 1 is incident on the object to be measured 4, the specularly reflected light is detected by the detector 2, and the unevenness of the object to be measured 4 and the position of the detector 3 are detected. Scattered light must be reliably detected regardless of the situation.

(c) Purpose of the Invention This invention provides a surface roughness meter that is capable of detecting specularly reflected light and scattered light, regardless of the direction of the unevenness, even when measuring a workpiece 4 having streak-like unevenness. The purpose is to provide.

(d) Embodiment of the Invention First, a block diagram of an embodiment of the invention is shown in FIG.

In FIG. 1, 5 and 6 are half mirrors, 17 is a light shielding plate, 8 is a slit, 9 is a condenser lens, 10 is a shaft, and other parts are the same as in FIG. 2.

Axis 10 is the traveling direction of specularly reflected light.

In FIG. 1, half mirror 5 and half mirror 6 are arranged in the following state.

The half mirror 5 reflects the light from the light source 1 and guides the reflected light along the axis 10 to the object to be measured 4.
The specularly reflected light from the object 4 is caused to pass along the axis 10 in the opposite direction to the light incident on the object 4 to be measured.

The half mirror 8 reflects the specularly reflected light from the object to be measured 4 and guides it to the detector 2, and allows the reflected and scattered light from the object to be measured 4 to pass toward the light shielding plate 7 side.

The light shielding plate 7 is arranged so as to be perpendicular to the reflected and scattered light from the object to be measured 4 .

The light shielding plate 7 is provided with an annular slit 8 centered on the axis lO, so that only the scattered light passing through the slit 8 reaches the condenser lens 9. The condensing lens 9 condenses the scattered light that has passed through the slit 8 of the light shielding plate 7 onto the light receiving surface of the detector 3.

As is clear from FIG. 1, even if the object to be measured 4 has streak-like irregularities, even if the entire optical system rotates around the axis 10,
The same group of scattered light rays always passes through the slit 8. Therefore, the amount of light received by the detector 3 is constant.

(e) Effects of the Invention According to this invention, since scattered light is detected by the half mirror 5 and the light shielding plate 8 with the annular slits 8, even when measuring an object with streak-like unevenness, specular reflection can be detected. Light and scattered light can be measured regardless of the direction of the unevenness.

[Brief explanation of drawings]

Fig. 1 is a block diagram of an embodiment according to the present invention, Fig. 2 is a block diagram of a conventional technique, Fig. 3 is a distribution diagram of reflected and scattered light, and Fig. 4 is a relationship between the position of the detector 3 and the scattered light pattern. figure. 1...Light source, 2...Detector, 3...
...Detector, 4...Measurement object, 5...
・Half mirror 16...Half mirror 17...
...jlf board, 8...slit, 9...
...Condensing lens, 10...axis. Agent Patent Attorney Kin Tsukasa Omata 1111a5 No. 211I No. 3 1 1L4B Detector April 1986-] Japanese Patent Office Commissioner Michibe Uga 1, Indication of Case 1985 Patent Application No. 141842 2, Invention Name Surface Roughness Meter Based on Reflected Light 3, Relationship with the case of the person making the amendment Patent Applicant Address 4-19-7 Kamata, Ota-ku, Tokyo Name Ando Electric Co., Ltd. Representative Shun Oshiro - 4, Agent 〒 144 Address 4-19-7-6 Kamata, Ota-ku, Tokyo Number of inventions increased by amendment 07 Target of amendment ``Detailed description of the invention'' column of the specification.

Claims (1)

[Scope of Claims] 1. A surface roughness meter that irradiates the object to be measured with light from a light source and detects specularly reflected light and scattered light from the object, which reflects the light from the light source to detect the object. a half mirror that irradiates the measurement object with light, and is arranged so that the irradiation light and the specularly reflected light are opposite to each other, and the specularly reflected light and the scattered light pass through; a light shielding plate provided with an annular slit arranged perpendicularly to the traveling direction of the specularly reflected light and centered on the traveling direction of the specularly reflected light; and a detector configured to detect the scattered light passing through the slit. A surface roughness meter that uses reflected light.