JPS61196111A - Flatness measuring apparatus - Google Patents

Abstract

PURPOSE:To enable the fast measurement of a 2-D shape of the entire plane while in noway damaging the surface to be measured, by providing a beam splitter, an objective lens, collimator lens, a fine lens and the like. CONSTITUTION:This apparatus is provided with a beam splitter 3, an objective lens 4, a collimator lens 6, a fine lens 7 and the like. Light from a light source 1 is expanded with a beam expander 2 and bent with the splitter 3 to be incident into the lens 4. The light from the lens 4 passes through a 1/4lambda plate 5 while being incident into the lens 6, where it is turned to a thick parallel flux to be incident into a fine lens array. In this array, a plurality of the same lenses 7 are stuck on a coverglass 8. Light introduced to the surface 9 to be measured is reflected thereon to be incident into the splitter 3 passing through the lenses 7 and 6, the plate 5 and the lens 4 again. Moreover, after the removal of noises with a spatial filter 10, the reflected light is introduced to a lens system 11, an observation surface 12 and a photoconductive element 13 to detect the intensity of light.

Description

Detailed Description of the Invention: a. Technical Field The present invention relates to a flatness measuring device that optically and non-contactly measures a general plane, particularly the shape of a pressure plate plane of a film inside a camera body, with high precision. It is something.

b. Prior art and its problems Conventionally, stylus-type means have been mainly used to measure the planar shape of a film pressure plate in a camera body. but,
With this method, 1. Since the needle comes into direct contact with the surface to be measured,
There is a risk of damaging the surface to be measured. Furthermore, in the case of stylus measurement, there are problems in that the number of observation points is limited to a few, making it difficult to two-dimensionally measure the entire plane, and also requiring a considerable amount of time.

C1 Purpose The present invention was made to solve the problems of the above-mentioned prior art, and by optically and non-contact measuring the planar shape of a pressure plate, etc., it is possible to measure without damaging the surface to be measured.
Another object of the present invention is to provide a flatness measuring device that can measure the two-dimensional shape of an entire plane at high speed.

d. Configuration of Example FIG. 1 is an explanatory diagram showing an example of the present invention, and the configuration will be explained along the optical path. Light source 1 is a small point light source He-
It is a Ne laser. The light from this light source 1 is expanded by a beam expander 2, and is then expanded by a polarizing beam splitter 3.
The beam is bent by the angle , and enters the objective lens 4 . The light from the objective lens passes through the quarter plate 5 and enters the collimator lens 6, where it becomes a thick parallel beam of light, and the parallel light beam enters the microlens array. This microlens array consists of identical microlenses 7
The structure is obtained by affixing a large number of lenses side by side on a cover glass 8 perpendicular to the optical axis. A surface to be measured 9 is placed near the focal point of the microlens array, and spot images having the same shape and size as the number of microlenses 7 appear on the surface to be measured 9.

This surface to be measured 9 can be moved in the direction of the optical axis as shown by the arrow in the drawing, and is connected to a movement amount detector (not shown) so that the amount of movement can be detected (determined in m). ing.

The light guided to the surface to be measured 9, that is, each spot image, is reflected there, and the reflected light is again passed through the microlens 7, collimator lens 6, 1/4 plate 5. The light passes through the objective lens 4 and enters the polarizing beam splitter 3. Here, the 1/4 input plate 5 provided between the objective lens 4 and the collimator lens 6 is for separating the light incident on the surface to be measured 9 and the light reflected from the surface to be measured 9. It is. The reflected light (spot image) incident on the polarizing beam splitter 3 passes through the polarizing beam splitter 3 and passes through a spatial filter provided at the condensing position of the objective lens 4.
) 10, the light is guided through a lens system 11 to an observation surface 12 provided at a position conjugate with the surface to be measured 9 with respect to the pupil of a microlens array (microlens). On this observation surface 12, the same number of photoelectric elements 13 as the microlenses 7 are arranged at positions corresponding to each microlens 7, and the light intensity of each microlens 7 is detected by the photoelectric elements 13 and photoelectrically converted. . This light intensity and the amount of movement of the surface to be measured 9 detected by the movement amount detector are linked by an arithmetic element (not shown).

In the above embodiment, a He No laser is used as the light source, but if the light source is an ordinary lamp, the
The plate 5 is no longer necessary, and the polarizing beam splitter 3 may of course be a beam splitter without polarizing characteristics.

e. Effect of Example Parallel light incident on the microlens array is condensed onto the surface to be measured 9, and has the same shape as the number of microlenses 7.

Spot images of the same size appear. If the surface to be measured 9 has irregularities, the size and shape of the spot image on the surface to be measured 9 will be non-uniform. Also, the surface to be measured 9 is exactly.

When the spot image is at the focal position of the microlens 7, the shape of the spot image becomes the smallest, and when the surface to be measured 9 shifts slightly back and forth, the spot image becomes larger.

On the other hand, on the plane (ai1!m plane) that is conjugate with the surface to be measured 9, photoelectric elements are arranged at positions corresponding to the respective microlenses 7, so that the reflected light from the surface to be measured 9, that is, the spot image is detected as light intensity.

Therefore, when the surface to be measured 9 is moved back and forth in the optical axis direction and an image is focused on each point on the surface to be measured 9, the light intensity generated by the amount of movement of the surface to be measured 9 is detected, photoelectrically converted, and the arithmetic element By processing this, the unevenness of the surface to be measured 9 can be determined.

f. Effects As explained above, according to the flatness measuring device of the present invention, the planar shape of the surface to be measured can be measured non-contact by using optical means, so the flatness measurement device can measure the planar shape of the surface to be measured without damaging the surface to be measured. It has become possible to measure flatness, and by arranging a large number of microlenses, it has become possible to measure the shape of a plane to be measured two-dimensionally and at high speed. As described above, the present invention has extremely high utility value in actual pressure plate shape measurement, etc.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram showing one embodiment of the present invention. 1: Laser light source 2: Beam Exno (Cedar 3 =
Polarizing beam splitter 4: Objective lens 5: 1/4 plate 6: Collimator lens 7: Microlens 8: Cover glass 9; Surface to be measured 10: Spatial filter (spatia
l filter) 11; Optical system for guiding the pupil of the microlens to the Wt measuring surface conjugately 12: Observation surface 13: Light receiving element Patent applicant Asahi Kogaku Kogyo Co., Ltd. 10 Procedural amendment November 27, 1985

Claims (1)

[Claims] 1. A small point light source, a means for converting the light from the light source into a thick parallel light beam, the same microlens array illuminated by the parallel light flux, and the vicinity of the focal plane of the microlens array. A surface to be measured that can be moved in the direction of the optical axis is placed in A beam splitter to separate the light,
An optical system that guides this reflected light to a position conjugate to the pupil of each microlens, a photoelectric detector that photoelectrically converts the light at a position conjugate to each microlens, and an output from this photoelectric detector. A flatness measuring instrument characterized by having an arithmetic element that connects the amount of movement of the surface to be measured with the amount of movement of the surface to be measured. 2. The flatness measuring instrument according to claim 1, characterized in that a laser is used as a light source. 3. The flatness measuring instrument according to claim 2, wherein the beam splitter is a polarizing beam splitter, followed by a 1/4 plate.