JPH06229745A - Planarity measuring equipment - Google Patents

Abstract

PURPOSE:To realize the noncontact measurement of planarity of smooth plane. CONSTITUTION:A part of a plane 10 to be measured is irradiated with a parallel spot light and the returning position of reflected light is detected by means of a CCD image sensor 7. The angle between the plane 10 to be measured and the irradiated part is then calculated and the measuring region of the plane to be measured is entirely scanned by the parallel spot light thus integrating the inclination component at each part of the plane to be measured. Since the planarity of the plane is calculated by simply detecting the returning position of reflected light, the planarity of smooth plane can be measured regardless of the fluctuation of reflectance thereof through a simple constitution.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a flatness measuring device for optically measuring the flatness (that is, straightness) of a smooth surface to be measured without contact.

[0002]

2. Description of the Related Art An optical method is generally employed as a method for measuring the flatness of an object surface as a surface to be measured without contact. For example, in the flatness measuring device disclosed in Japanese Patent Laid-Open No. 61-196111, the entire surface to be measured is moved back and forth in the direction of the optical axis, and the surface is irradiated with parallel light rays passing through a large number of microlenses to locally. The flatness is measured from the change in spot diameter of the reflected light.

[0003]

However, in the above-mentioned conventional technique, when the reflectance of the surface to be measured varies, the intensity distribution of the reflected light varies depending on the irradiation position of the parallel light rays, so that the measurement accuracy is high. There was a problem that I could not do it. In addition, the configuration of the measuring device is complicated because it requires an optical element in which a large number of the same microlenses are attached to the cover glass and a highly accurate moving stage for moving the surface to be measured back and forth in the optical axis direction. However, there is a problem that the cost becomes high.

An object of the present invention is to solve the above-mentioned problems of the prior art and to measure the flatness of the surface to be measured by the contact without being influenced by the variation in the reflectance of the surface to be measured with a simple structure. An object of the present invention is to provide a flatness measuring device capable of performing the above.

[0005]

In order to achieve the above object, the present invention irradiates a part of the surface to be measured with parallel light spots, and the returning position of the reflected light is detected by a light detecting means such as a CCD image sensor. The principle of detection is to calculate the angle that the irradiated portion of the surface to be measured is facing, and the parallel light spot is scanned over the entire measurement area of the surface to be measured to incline each part of the surface to be measured. It is designed to integrate the components.

That is, according to the present invention, in a flatness measuring device for optically measuring the flatness of a smooth surface to be measured without contact, a parallel light spot irradiating means for irradiating the surface to be measured with a parallel light spot. And a parallel light spot scanning means for scanning the parallel light spot on the surface to be measured, and receiving reflected light from the surface to be measured to detect the irradiation position of the parallel light spot on the surface to be measured. It is characterized by comprising a reflected light beam return position detection means and a flatness calculation processing means for calculating the flatness of the surface to be measured from the detection output of the reflected light beam return position detection means.

[0007]

The parallel light spot irradiation means irradiates the light from the light source as parallel light spots on the surface to be measured. The reflected light from the surface to be measured reaches the photodetector element. The parallel light spot is moved so as to two-dimensionally scan the entire measurement area of the surface to be measured.

The flatness calculation processing means integrates the return position signal obtained from the photodetector in synchronism with the scanning of the surface to be measured of the parallel light spot to detect the inclination of each portion of the surface to be measured, and then the object to be measured. The flatness of the measuring surface is measured.

[0009]

Embodiments of the present invention will now be described in detail with reference to the drawings. FIG. 1 is a block diagram of an embodiment of a flatness measuring device according to the present invention, in which 1 is a light source, 2 is a slit, 3 is a beam splitter, 4 is a collimator lens, and 5 is a collimator lens.
Is a movable window, 6 is a movable window driving means, 7 is a CCD image sensor, 8 is flatness calculation processing means, 9 is a parallel light beam irradiation mechanism, and 10 is a surface to be measured.

In the figure, the light from the light source 1 is spread through the slit 2 and bent by the beam splitter 3 toward the surface to be measured. The light from the beam splitter 3 is collimated by the collimator lens 4, passes through the slit of the movable window 5, and is projected as a spot on a part of the surface 10 to be measured. The light beam reflected by the surface to be measured 10 has the slit 51 of the movable window 5 → the collimator lens 4 → the beam splitter 3
The light is incident on the light detection surface of the CCD image sensor 7 through the path.

The CCD image sensor 7 detects the position of the incident light spot to calculate the inclination of the partial surface 101 of the portion to be measured 10 on which the spot light is irradiated. Then, the position of the movable window 5 is moved by the movable window driving means 6 to irradiate the partial surface 102 of the measured surface 10 adjacent to the partial surface 101 with the parallel light spot. The reflected light from the partial surface 102 is incident on the light detection surface of the CCD image sensor 7, and the inclination of the partial surface 102 is calculated in the same manner.

Then, the movable window 5 is moved by the movable window driving means 6 to scan spot light over the entire measurement area of the surface 10 to be measured, and the inclination of the partial surface of the entire measurement area of the surface to be measured is calculated. The flatness of the surface to be measured is measured by processing this data by the flatness calculation processing means 8. This flatness is calculated as follows.

FIG. 2 shows an example of the flatness measurement result of the surface to be measured.
It is a graph figure which shows, and the horizontal direction is a predetermined direction length of the partial surface.
And the vertical axis indicates the flatness. The inclination of a certain partial surface 101
If θ and the length of this partial surface are L, both ends of the partial surface
The difference in height is L · sin θ. That is, in FIG.
The length of each partial surface is ΔL, and the inclination of the partial surface 101 is θ.
₁Then, the difference in height between both ends of this part is ΔL · sin θ₁
And the inclination of the partial surface 102 is θ₂Then, this part
The difference in height between the two ends is ΔL ・ sinθ₂Is.

This calculation processing is executed for all adjacent partial surfaces, and all the data are connected and integrated to obtain a graph of flatness d as shown in FIG. The measurement resolution obtained at this time is determined by the length ΔL of the partial surface to be measured. For example, when ΔL = 5 mm and the reading unit of the minimum inclination is 1 second,
L · sin 1 = 0.024 μm.

A commercially available photoelectric autocollimator can be used for the parallel light beam irradiation mechanism 9 in which the light source 1, the slit 2, the beam splitter 3, the collimator lens 4, and the CCD image sensor 7 in FIG. 1 are integrated. As the flatness calculation processing means 8, a commercially available personal computer can be used. Since the movable window drive mechanism 6 that moves the movable window 5 does not require a highly accurate positioning mechanism, it can be configured with a low cost and simple mechanism.

FIG. 3 is a schematic configuration diagram of another embodiment of the flatness measuring apparatus according to the present invention, in which 90 is a parallel light beam irradiation mechanism in which a slit window 50 is integrated, 11 is, for example, an X-direction precision moving mechanism, and 12 is. Is a Y-direction precision moving mechanism, for example. When the area of the surface to be measured is large, the X-direction precision moving mechanism 11 for moving the parallel light beam irradiation mechanism 90 in which the slit window is integrated as in this embodiment in the X and Y directions parallel to the surface to be measured. , The Y-direction precision moving mechanism 12 is used to sequentially move to the partial surface.

In this embodiment, the parallel light irradiation mechanism 90 is used.
However, instead of this, the surface to be measured 10 side may be moved by a similar moving mechanism. In each of the above embodiments, the flatness can be measured at a fine interval by reducing the size (irradiation area) of the parallel light spot or reducing the movement interval ΔL.

[0018]

As described above, according to the present invention,
Since the flatness of the measured surface is calculated only by detecting the returning position of the reflected light beam, a simple structure that can measure the smoothness of the measured surface without being affected by the dispersion of the reflectance of the measured surface. A flatness measuring device can be provided.

[Brief description of drawings]

FIG. 1 is a configuration diagram of an embodiment of a flatness measuring device according to the present invention.

FIG. 2 is a graph showing an example of a flatness measurement result of a surface to be measured.

FIG. 3 is a schematic configuration diagram of another embodiment of the flatness measuring device according to the present invention.

[Explanation of symbols]

1 ... Light source, 2 ... Slit, 3 ... Beam splitter, 4 ... Collimator lens, 5 ...
・ Movable window, 6 ・ ・ ・ ・ Movable window driving means, 7 ・ ・ ・ ・ CC
D image sensor, 8 ... Flatness calculation processing means, 9
・ ・ ・ ・ Parallel light irradiation mechanism, 10 ・ ・ ・ ・ Measured surface, 5
0 ... Slit window, 90 ... Parallel light irradiation mechanism integrating slit window, 11 ... X direction precision movement mechanism, 12 ... Y direction precision movement mechanism.

Claims (1)

[Claims] 1. A flatness measuring device for optically measuring the flatness of a smooth surface to be measured in a non-contact manner, comprising: parallel light spot irradiating means for irradiating the surface to be measured with parallel light spots; Parallel light spot scanning means for scanning a light spot on the surface to be measured, and a reflected light return position for receiving the reflected light from the surface to be measured and detecting the irradiation position of the parallel light spot on the surface to be measured. A flatness measuring device comprising: a detecting means; and a flatness calculation processing means for calculating the flatness of the surface to be measured from the detection output of the reflected light return position detecting means.