JPS626111A - Surface roughness meter by reflected light - Google Patents

Abstract

PURPOSE:To eliminate an error caused by a distance between an object to be measured and a detector, by condensing by a lens a specularly reflected light and a scattered light which have been obtained by irradiating the surface of the object to be measured, from a light source, after making them travel straight through a half mirror, and irradiating them to each detector. CONSTITUTION:Light from a light source 1 is reflected by a half mirror 5 and irradiated to the surface of an object to be measured 4. A specularly reflected light L0 among the light beams which have been reflected by the surface passes through the same path (axis 7) as an incident light, travels straight through the half mirror 4 and made incident on a detector 2. A scattered light L1 which has been brought to an irregular reflection at an angle theta 11 on the surface passes through the half mirror 5, condensed by a lens 6 and made incident on a detector 3. Even if the object to be measured 4 moves to 4' and 4'' as shown in the figure by a dotted line, scattered light beams L1', L2'' pass through the lens 6 in the same way, and made incident on the detector 3. In this way, even if the object to be measured moves forward and backward a little, the specularly reflected light and the scattered light having a prescribed scattering angle are measured exactly and an error of a measurement of roughness can be reduced.

Description

Detailed Description of the Invention (a) Technical Field of the Invention This invention irradiates a VL measurement object with light from a light source, detects specularly reflected light and scattered light from the measurement object, and detects the surface of the measurement object. surface roughness that allows the detection of specularly reflected light and scattered light with a constant scattering angle even if the distance between the object to be measured and the detector changes slightly. It is related to the meter.

(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 e, and specularly reflected light from the object to be measured 4 is reflected at an angle of reflection θ. 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.

In the conventional technology shown in FIG. 2, the distance between the detector 2 and the detector 3 is fixed, so when the distance between the detector 2 and the object to be measured 4 changes, the constant amount of light from the object to be measured 4 will change. The detector 3 will no longer be able to detect scattered light with a scattering angle.

Next, detector 2. The state when the distance between the detector 3 and the object to be measured 4 changes will be explained with reference to FIG. 3.

Ll in Figure 3 is the distance between detector 2 and detector 3, L2 and L3
is the distance between the detector 2 and the object to be measured 4.

In FIG. 3, L3>L2, and the relationship between the scattering angle θ2 when the distance is L2 and the scattering angle e3 when the distance is L3 is θ2>θ3.

As is clear from FIG. 3, when the distance between the detector 2 and the object to be measured 4 changes, the scattering angle of the scattered light reaching the detector 3 changes.

In order to eliminate such problems, the light source 1, the object to be measured 4
, the positional relationship between detector 2 and detector 3 must be kept constant.

(c) Purpose of the Invention The present invention has a surface roughness that makes it possible to detect specularly reflected light and scattered light with a constant scattering angle even if the distance between the object to be measured 4 and the detectors 2 and 3 changes. The purpose is to provide a meter.

(d) Examples of the invention A block diagram of an embodiment according to the present invention is shown in FIG.

In FIG. 1, 5 is a half mirror, 16 is a lens, 7 is a shaft, and other parts are the same as in FIG.

Axis 7 is the traveling direction of specularly reflected light.

In FIG. 1, the half mirror 5 is arranged in the following state.

The half mirror 5 reflects the light from the light 81 and guides the reflected light to the object to be measured 4 along the axis 7, so that the specularly reflected light from the object to be measured 4 is exactly opposite to the light incident on the object to be measured 4. The scattered light from the object to be measured 4 is passed along the axis 7 in the direction of .

The center of the lens 6 is aligned with the axis 7, the detector 3 is placed at the back focal plane of the lens 6, and the lens 6 is arranged so that the detector 3 detects the scattered light at a certain angle that is incident on the lens 6. Configure.

As is clear from FIG. 1, even if the distance between the VL measurement object 4 and the half mirror 5 changes like Lll, L12, Ll3, the detector 3 always detects the light beam with the same scattering angle θ11 by the lens 6. can do.

(e) Effects of the Invention According to this invention, since the half mirror 5 and the lens 6 that converges scattered light with a certain scattering angle are used,
Even if the distance between the detector 3 and the object to be measured 4 changes somewhat, specularly reflected light and scattered light having a constant scattering angle can be reliably measured.

[Brief explanation of the drawing]

Fig. 1 is a block diagram of an embodiment according to the present invention, Fig. 2 is a block diagram of a conventional technique, and Fig. 3 is a state explanatory diagram when the distance between the detector 2, the detector 3, and the [lJ constant object 4] changes. . ■・・・Light source, 2...Detector, 3...
...Detector, 4...Measurement object, 5...
・Half mirror 18...Lens, 7...
·shaft. Agent Patent Attorney Tsukasa Omata No. 1 Figure: Body fixed object No. 2 Figure 3: Object to be measured

Claims (1)

[Scope of Claims] 1. A surface roughness meter that irradiates a measured object with light from a light source and detects specular reflected light and scattered light from the measured object with a detector, comprising: reflecting the light from the light source; a half mirror arranged so that the irradiated light and the specularly reflected light are opposite to each other, and the specularly reflected light and the scattered light pass through; The detector is arranged so as to match the traveling direction of the specularly reflected light, and the detector detects the scattered light with a constant scattering angle from the object to be measured even if the distance between the detector and the object to be measured changes. A surface roughness meter using reflected light, characterized in that it is equipped with a lens configured to detect the surface roughness.