JPS5845515A - Controller for detecting position of surface - Google Patents

Abstract

PURPOSE:To improve the accuracy of detection and to detect a surface to be detected correctly despite minor inclination of the surface by forming the image of the image-forming light of a micropattern reflected by said surface again onto the surface to be detected and detecting the image-forming position of said reflected light. CONSTITUTION:A micropattern of a slit S or the like is formed on a surface A to be detected by image-forming optical systems 6, 8, and the image-forming light reflected by a surface A is formed the image again on the surface A by an optical system for reflection of an unmagnified real image such as a concave mirror 9. The image-forming light reflected by the surface A is conducted through, for example, a prism 7 or the like onto the photodetecting surface of a photoelectric element 11 or 13, and the change in the image-forming position on the photodetection surfaces thereof is detected, whereby the position of the surface A is detected and controlled. For example, a projecting lens L0 and the entire part of the optical system of the device are moved in one body in the optical axis direction of the lens L0 by a moving device for the optical system, whereby a sliding projector is focused automatically.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a surface position detection control device used for automatic focus adjustment of slide projectors, binocular stereomicroscopes, and the like.

A conventional surface position detection control device of this type, as shown in FIG. An imaging lens 3 forms an image S1 on the test surface A, an imaging lens 4 re-images the light specularly reflected by the surface A as a full image S2, and the light-receiving surface coincides with the imaging surface of the image S2. It consists of a light-receiving element 5 arranged as shown in FIG.
A distance of 4D from the correct position of surface A in the direction of the optical axis of the projection lens.
If the light that should become the image S1 is reflected by the surface A' and then formed as the images S, l, the distance between the images S, , S□' is 2D. In this case, if the magnification of the imaging lens 4 is m, the original image S2 will move on the light receiving surface of the light receiving element 5 by a distance of approximately 2 mD and become the image S2. It is photoelectrically detected and fed back so that the distance 2 mD becomes zero. That is, the projection lens Lo and the entire optical system of this device are moved as one in the optical axis direction of the projection lens Lo by an optical system moving device so that the image S+ is on the plane. However, the accuracy of this surface position detection control device was not sufficient, and as the text surface A tilted, the angle of the specularly reflected light from surface A changed. As a result, the incident position with respect to the imaging lens 4 changes, and this appears as a change in the position of the image S2', resulting in a problem that detection cannot be performed correctly.

In view of the above-mentioned problems, it is an object of the present invention to provide a surface position detection control device that greatly improves detection accuracy and allows accurate detection even when the surface is slightly tilted. The following description will be based on the embodiment shown in FIGS. 3 to 5, with the same reference numerals given to the same members as in the conventional example above. 6 represents the light emitted from the slit S. An imaging lens 7 forms an image SO on the top of a prism, which will be described later. 7 is a prism whose top is polished into a slit shape. 8 is an image 5o (i) which directs the emitted light onto the surface A to be inspected. An imaging lens 9 is arranged so that the center of curvature is on the image S1, and collects the light specularly reflected by the surface A. A concave mirror 10 that reflects the light and forms it again on the image Sl is placed on one side of the prism 7, and a light receiving element 11 that is also placed on one side receives the light reflected from one slope of the prism 7. An imaging lens 12 is arranged on the other side of the prism 7 to condense the light onto the light-receiving surface. It is an imaging lens that focuses light on a light receiving surface. Both light receiving elements 11 and 13 are connected to an optical system moving device (not shown).
ing.

The surface position detection control device according to the present invention is constructed as described above.
Therefore, as shown in Fig. 4, the surface A is the projection lens b.
If the light that should become image S+ is reflected by surface A', it will be formed as image Sl', and in this case, the distance between images S1+ Sl' The distance is 2D. Next, the light emitted from the image Ss'ffi is reflected by the concave mirror 9 and attempts to form an image SW, but this light is re-reflected by the surface A' and forms an image S, #l. In this case, the distance between images S+'+St' is approximately 4
D, so the distance between the images St+Sl' is also approximately 4D (the distance between the images Ss and Sl'i is approximately 6D).
. Next, the light emitting images S and III forms an image So' at a position f' outward from the top of the prism 7, and an image So'e
The emitted light is reflected by one slope of the prism 7 and then focused by the imaging lens 10 onto the light receiving surface of the light receiving element 11. - If the surface A moves in the opposite direction to the surface A', the slit image light beam is reflected by the other surface of the prism 7 based on the same principle as above, and then transferred to the imaging lens 12. The light is focused on the light receiving surface of 13. Therefore, the outputs of the light-receiving elements 11 and I3 are fed so that they become zero, that is, the projection lens and the entire optical system of this apparatus are moved as one in the direction of the optical axis of the projection lens using the optical system moving device, so that the image Sl is By controlling the tilt so that it is on the plane A', it can be aligned with the focal plane A' of the projection lens b. In this way, the present apparatus is operated, but the present apparatus is capable of forming an image S! which is to be formed on the plane A at the time of focusing, even though the plane A has only moved by D as described above. Since the distance between the final image 81'' formed after being reflected by the surface A' and the concave mirror 9 is approximately 4D, the sensitivity is doubled and the detection accuracy is greatly improved compared to the conventional example.

Furthermore, as shown in FIG. 5, even if surface A tilts in the focused state and becomes surface A', the inclination of the specularly reflected light changes, if the effective diameter of the concave mirror 9 is made sufficiently large, all specularly reflected light will be removed. Since the light can be captured, reflected, and sent back along the original optical path to form an image on the top of the prism 7,
Detection is done correctly.

FIG. 6 shows the second embodiment, and when the light emitted from the slit S is focused by the imaging lens 6 on the incident end surface, the exit end surface becomes a kind of slit-shaped light source. Optical fiber sheets 15 and 16 are optical fiber sheets formed by arranging optical fibers or optical fibers in a straight line, and 15 and 16 are optical fiber bundles whose incident end faces are arranged on both sides of the exit end face of the optical 7-14. These are provided in place of the prism 7 of the first embodiment.

Therefore, when the focus is correct, that is, when the image S+ is on the surface A, the light does not return to any of the optical 7-eye bundles 15 and 16, but when the focus is shifted, that is, the surface A moves. In this case, the return light is optical 7-eye.
Either bundle 15 or 16 is captured on one side, and as a result an output is generated on either one of light receiving elements 11 or 13, so automatic focus adjustment of surface A is possible by selecting this information. Become. In this embodiment, several layers of optical fiber bundles 15 and 16 are stacked in regular alignment at the input end face, and are separated one layer at a time at the exit end face and applied to the light receiving surfaces of a plurality of light receiving elements. If the image Sot in the first embodiment is constructed by guiding the image So
It is also possible to measure the distance corresponding to So'.

FIG. 7 shows a third embodiment, in which 17 is an imaging lens and 18 is a plane reflecting mirror, which are provided in place of the concave mirror 9 of the first embodiment.

Moreover, 19 and 20 are solid-state imaging devices such as CCDs provided in place of the position detection devices of the second embodiment, which reflect the return light of the image So on the slope of the prism 7 and then pass through the imaging lens. 10 or 12 on the solid-state image sensor 19 or 20, it is possible to measure the distance corresponding to the distance between the images Son So' in the first embodiment, similarly to the second embodiment.

FIG. 8 shows a fourth embodiment, in which imaging lenses 21 and 22 are provided in place of the imaging lens 8 of the first embodiment, and make the rays between them parallel rays. , 23
24 is a semi-transparent mirror arranged between the imaging lenses 21 and 22 to take out the returned light to the side; 24 is a semi-transparent mirror 23 that reflects the returned light f'Lfc, and forms the returned light on the position detection element 25 as an image S2. It is an imaging lens that Therefore, by detecting the change in the position of the image S2, the displacement distance Dt of the image A can be detected.

FIG. 9 shows an example in which the fourth embodiment is applied to a single-objective type binocular stereomicroscope, where 26 is an objective lens, 27 and 28 are imaging lenses of the left and right optical systems, and these are the objective optical system. The light rays between the imaging lenses 27 and 28 and the objective lens 26 are parallel rays. Further, 29 and 30 are flat reflecting mirrors. Therefore, the emitted light is converted into a parallel beam bundle by the imaging lens 21, reflected by the plane reflecting mirror 29, and then reflected by the objective lens 26 onto the surface A.
A slit image Sl is formed on the top. Next, the light that is almost specularly reflected at A passes through the objective lens 26, becomes a parallel ray, and enters the plane reflecting mirror 30.
The fLfc light reflected at 0 is again focused on the image Sl on the surface A by the objective lens 26, and the light almost specularly reflected at the surface A is made incident on the plane reflecting mirror 29 again. Furthermore,
The light reflected by the flat reflecting mirror 29 is reflected by the semi-transparent mirror 23 and then formed into an image S2 on the position detection element 25 by the imaging lens 24.
It is imaged as Therefore, when the surface A goes out of focus, the position of the image S2 will shift on the position detection element 25, so by detecting the change in the position of the image S2, the displacement distance of the surface A can be detected. It is also possible to automatically focus correctly on surface A by selecting the feet. In addition, in such an optical system, a plane including the optical axes of the imaging lenses 27 and 28, a slit S,
Imaging lens 21° flat reflecting mirrors 29 and 30, semi-transparent mirror 23
By obliquely intersecting the planes containing the detection system consisting of the above, the whole can be made into a compact structure. Further, in the first, second, and third embodiments, if the objective optical system of a binocular stereomicroscope is substituted for the imaging lens 80, an application example similar to this application example can be constructed.

Incidentally, in each of the above embodiments, a slit tray S is used, but in order to increase the amount of light, a minute grating may be used instead of the slit S, or a ring-shaped slit may be used. Further, as the light used, invisible light such as infrared rays or ultraviolet rays may be used as necessary.

As described above, the surface position detection control device according to the present invention has the advantage that detection accuracy is extremely high and correct detection is performed even if the surface to be detected is slightly tilted.

[Brief explanation of drawings]

FIG. 1 is a diagram showing the optical system of a conventional surface position detection control device.
FIG. 2 is a diagram showing the imaging state when the surface to be inspected moves in the conventional example, FIG. 3 is a diagram showing the optical system of an embodiment of the surface position detection control device according to the present invention, and FIG. FIG. 5 shows the state of image formation when the surface to be measured is tilted in the above embodiment, and FIG. 6 to FIG. FIG. 9 is a diagram showing the optical system of an example in which the fourth embodiment is applied to a single-objective binocular apex microscope. 1... Light source, 6... Imaging lens, 7... Prism, 8... Imaging lens, 9... Concave surface power, 10.12.
...Imaging lens, 11.13... Light receiving element, S...
Slit, A...Test surface. Figure 1-6 Off view

Claims (4)

[Claims] (1) A microscopic figure is imaged on the test surface by an imaging optical system, and the reflected light of the imaged light from the test surface is imaged again on the test surface by a real image reflection optical system. Further, the imaging light is reflected by the test surface and guided onto the light-receiving surface of the gold photoelectric element, and the change in the image-forming position on the light-receiving surface is detected to detect and control the position of the test surface. A surface position detection control device constructed as follows. (2) The surface position detection control device according to claim (1), wherein the minute figure is a single slit or a grid. (3) Claims characterized in that the equal-magnification real image optical system is a concave mirror having a center of curvature on the test surface (
1) The surface position detection control device according to item 1). (4) The surface position detection control device according to claim (1), wherein the equal-magnification real image optical system is a refractive/reflective optical system having a focal point on the test surface.