JPS6345523B2 - - Google Patents

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.

This type of conventional surface position detection control device, as shown in FIG. an imaging lens 3 that forms an image _S1 on a surface A to be inspected, and an imaging lens 4 that reimages the light specularly reflected by the surface A as an image _S2 .
and a light-receiving element 5 which is arranged so that its light-receiving surface coincides with the imaging plane of the image _S2 and which is connected to an optical system moving device (not shown), so that the surface A is in the correct position as shown in FIG. Suppose that the projection lens _L0 is translated by a distance D in the direction of the optical axis from L0 to the surface A'.
The light that should become image S ₁ is reflected by surface A' and then formed as image S ₁ ', and the distance between images S ₁ and S ₁ ' is 2D. In this case, the magnification of the imaging lens 4 is m. If there is an original statue
Since S ₂ moves approximately 2 mD on the light receiving surface of the light receiving element 5 to form an image S ₂ ', the distance 2 mD is photoelectrically detected by the light receiving element 5, and feedback is performed so that the distance 2 mD becomes zero. The system moving device moves the projection lens L ₀ and the entire optical system of this device as one in the optical axis direction of the projection lens L ₀ to create an image S _{1 .}
was controlled so that it was on plane A'.
However, the precision of this surface position detection control device itself is not sufficient, and when surface A is tilted, the slope of the specularly reflected light by surface A changes, causing the imaging lens 4
There was a problem in that detection was not performed correctly because the incident position on the image S ₂ ' changed and this appeared as a change in the position of the image S 2 '.

In view of the above-mentioned problems, the present invention aims to provide a surface position detection control device that greatly improves detection accuracy and enables accurate detection even when the surface is slightly tilted. The following description will be made 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 is a slit S which is an index for surface position detection.
An imaging lens that forms the light emitted from the prism as an image S ₀ on the vertex of the prism described later; 7 is a prism whose top is polished into a slit shape; 8 is a prism that emits the image S ₀ ; An imaging lens 9 forms an image S ₁ on the surface A and also forms the light emitted from the image S ₁ onto an image S ₀ again, and is arranged so that the center of curvature is on the image S ₁ . A concave mirror 10, which is a real image reflection optical system of equal magnification, reflects the light specularly reflected by the surface A and forms it again on the image _S1 , and is arranged on one side of the prism 7. An imaging lens 12 focuses the reflected light on the light receiving surface of the light receiving element 11 also placed on one side, and 12 is placed on the other side of the prism 7 and reflects the light on the other slope of the prism 7. This is an imaging lens that focuses the light onto the light-receiving surface of the light-receiving element 13, which is also placed on the other side. Both light receiving elements 11 and 13 are connected to an optical system moving device (not shown).

Since the surface position detection control device according to the present invention is configured as described above, as shown in FIG.
Suppose that the image is translated by a distance D in the direction of the optical axis of the projection lens L ₀ and transferred to the surface A', then the light that should form the image S ₁ is reflected by the surface A' and then formed as the image S ₁ '. , in this case the distance between S ₁ and S ₁ ' is 2D. Next, the statue
The light emitted by S ₁ ′ is reflected by the concave mirror 9 and becomes an image.
An attempt is made to form an image as S ₁ ', but this light is re-reflected by surface A' and is formed as image S ₁ . In this case, the statue
Since the distance between S ₁ ′ and S ₁ ″ is approximately 4D, the images S ₁ and S ₁
The distance between them is also approximately 4D (the distance between images S ₁ ″ and S ₁ is approximately 6D).Next, the light emitted from image S ₁ forms image S ₀ at a position away from the top of prism 7. ', and the light emitted as an image S ₀ ' 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.On the other hand, the surface A is a surface Assuming that it moves in the opposite direction to A', the slit image ray bundle is reflected by the other surface of the prism 7 and then focused on the light receiving surface of the light receiving element 13 by the imaging lens 12 based on the same principle as above. .
Therefore, the projection lens L ₀ and the entire optical system of this apparatus are projected as one by providing feedback so that the outputs of the light receiving elements 11 and 13 are zero or the difference in output between the light receiving elements 11 and 13 is zero. The image S ₁ that is moved in the optical axis direction of the lens L ₀ is a surface.
If the projection lens L0 is controlled so that it is placed on the plane A', the focus of the projection lens _L0 can be adjusted to the plane A'. In this way, the operation of the present device is carried out, but as mentioned above, the present device is able to separate the image S1 that should be formed on the surface A at the time of focusing by moving the surface A only by D, and the image _S1 reflected by the surface A' and the concave mirror 9. The distance between the final image _S1 created after
Therefore, compared to the conventional example, the sensitivity is doubled and the detection accuracy is greatly improved. Also, as shown in Figure 5,
Even if surface A tilts in the focused state to become surface A' and the inclination of the specularly reflected light changes, if the effective diameter of the concave mirror 9 is made sufficiently large, all the specularly reflected light will be captured and reflected, returning to the original optical path. Since the light beam can be sent back along the same direction and focused on the top of the prism 7, the detection can be performed correctly.

FIG. 6 shows a second embodiment, in which when the light emitted from the slit S is focused by the imaging lens 6 on the incident end surface 14, the exit end surface becomes a kind of slit-shaped light source _S0. Optical fiber sheet or optical fiber sheet formed by arranging optical fibers in a straight line, 15
and 16 are optical fiber bundles whose incident end faces are arranged on both sides of the exit end face of the optical fiber 14, and these are provided in place of the prism 7 of the first embodiment.
Therefore, if the image is in focus, that is, the image is on surface A.
If S ₁ exists, the light does not return to either the optical fiber bundles 15 or 16, but if the focus shifts, that is, if the surface A moves, the returned light returns to either the optical fiber bundles 15 or 16. As a result, an output is generated on either the light receiving element 11 or 13, so automatic focusing of the surface A becomes possible by feeding back this information. In this embodiment, the optical fiber bundles 15 and 16 are formed by stacking several layers of optical fiber sheets in regular alignment at the input end face, and separating them one by one at the exit end face, respectively, onto the light receiving surfaces of the plurality of light receiving elements. If the structure is constructed by guiding the elements, or by guiding them to the position detection element in a regularly arranged and stacked state,
It is also possible to measure the distance corresponding to the images S ₀ and S ₀ ' in the first embodiment.

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.
Further, 19 and 20 are solid-state imaging devices such as CCDs provided in place of the position detecting device of the second embodiment, which form an image after reflecting the return light of the image _S0 on the slope of the prism 7. If an image is formed on the solid-state image sensor 19 or 20 by the lens 10 or 12, the image S ₀ ,
The distance corresponding to S ₀ ' can be measured.

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 are imaging lenses 21 and 22
A semi-transparent mirror 24 disposed between them for returning the returned light to the side is an imaging lens that forms the returned light reflected by the semi-transparent mirror 23 on the position detection element 25 as an image S ₂ . Therefore, the displacement distance D of the surface A can be detected by detecting the change in the position of the image _S2 .

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 right and left 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 light emitted from the slit S is turned into a parallel beam by the imaging lens 21, reflected by the plane reflecting mirror 29, and then imaged onto the surface A by the objective lens 26 as a slit image _S1 . Subsequently, the light that is almost specularly reflected from the surface A passes through the objective lens 26 and becomes parallel light beams and enters the plane reflecting mirror 30, and the light reflected by the plane reflecting mirror 30 is converted into an image on the plane A by the objective lens 26. The light that is imaged again on S ₁ and almost specularly reflected by surface A is reflected again on plane reflecting mirror 2.
9. Further, the light reflected by the plane reflecting mirror 29 is reflected by the semi-transparent mirror 23 and then focused on the position detecting element 25 as an image S ₂ by the imaging lens 24 . Therefore, when surface A goes out of focus, the position of image _S2 will shift on the position detection element 25, so by detecting the change in the position of image _S2 , the displacement distance of surface A can be detected. , it is also possible to feed this back and automatically focus on surface A correctly. In addition, in such an optical system, there is a plane containing the optical axes of the imaging lenses 27 and 28, and a plane containing the detection system consisting of the slit S, the imaging lens 21, the flat reflecting mirrors 29 and 30, the semi-transparent mirror 23, etc. By intersecting them, you can make the whole thing more compact. Furthermore, if the imaging lens 8 in the first, second, and third embodiments is replaced with the objective optical system of a binocular stereomicroscope, an application similar to this application can be constructed.

Incidentally, each of the above embodiments uses the slit S, 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 excellent advantage of extremely high detection accuracy and correct detection even if the surface to be detected is slightly tilted.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing the optical system of a conventional surface position detection control device, FIG. 2 is a diagram showing the image formation state when the surface to be detected moves in the conventional example, and FIG. 3 is a diagram showing the surface position according to the present invention. FIG. 4 is a diagram showing the optical system of an embodiment of the detection control device. FIG. 4 is a diagram showing the image formation state when the surface to be detected moves in the above embodiment. FIG. Figure 6 showing the state
Figures 8 to 8 are diagrams showing the optical systems of the second, third, and fourth embodiments, respectively, and Figure 9 is the optical system of an example in which the fourth embodiment is applied to a single-objective binocular stereoscopic microscope. FIG. 1... Light source, 6... Imaging lens, 7... Prism, 8... Imaging lens, 9... Concave mirror, 10,1
2... Imaging lens, 11, 13... Light receiving element, S
...Slit, A...Test surface.

Claims (1)

[Claims] 1. An imaging optical system that projects light from a detection target obliquely onto a surface to be tested to form an image of the detection target on the surface to be tested, and a reflecting member. and an equal-magnification real image reflecting optical system that receives reflected light from the test surface and reflects it on the reflecting member to form an index image again at the same position as the index image when the test surface is in a normal position. , an optical element disposed within the imaging optical system and extracting at least a part of the light reflected by the test surface to outside the optical path of the imaging optical system; and the light extracted by the optical element. and a photoelectric conversion means that is placed on the road and receives the light, and a surface position that detects the position of the test surface based on a change in an output signal from the photoelectric conversion means in accordance with a change in the position of the test surface. Detection control device. 2. The surface position detection control device according to claim 1, wherein the detection index is a slit or a grid. 3. The surface position detection control device according to claim 1, wherein the same-magnification real image optical system is a concave mirror having a center of curvature on the surface to be inspected. 4. The surface position detection control device according to claim 1, wherein the same-magnification real image optical system is a refractive/reflective optical system having a focal point on the surface to be inspected.