JPH02134508A - Tilt detection head - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a tilt detection head for inspecting the tilt of an optical disk, semiconductor wafer, liquid crystal TV glass substrate, CCDCD imaging plate, or adjusting the tilt based on the inspection. It is something.

Conventional technology As a tilt detection head that detects the tilt of a flat plate without contact,
Some use a convex lens and an optical position detection element.

In FIG. 3, 61 is a semiconductor laser light source, 62 is a collimator lens, 63 is a beam splitter, 164 is an object to be measured, 66 is a convex lens, 56 is an optical position detection element, and the optical position detection element 66 is approximately the focal point of the convex lens 66. installed in position. With this configuration, the nearly parallel light emitted from the collimator lens 62 and transmitted through the beam splitter 63 is irradiated onto the object to be measured 64, and the object to be measured 64 is
If it is tilted, it will be reflected in a 2θ tilted direction. The reflected light is reflected by the beam splitter 63 and passed through the convex lens 66.
is incident on the optical position detection element 68 from the optical axis f as
The light is focused at a position shifted by in (2θ). However, f is the focal length of the convex lens 65. Furthermore, even when the object to be measured 64 is tilted in a direction perpendicular to the plane of the paper, the light is similarly focused on the optical position detection element 66 at a position deviated from the optical axis in the direction perpendicular to the plane of the paper. Therefore, it can be seen that the tilt in any direction can be detected by the optical spot position on the optical position detection element 66.

Problems to be Solved by the Invention However, with the above configuration, in order to increase the detection resolution and expand the detection range, it is necessary to increase the focal length of the convex lens, which requires a large-scale optical system. , which has the problem of being difficult to implement.

For example, in an optical system with a resolution of 10 d@g and a detection range of 1 dig, if the dimensions of the optical position detection element are 6 mm, then fφsin (2) = 5, so f = 143 ms, and the distance between the convex lens and the optical position is Since the distance between the detection elements is 140 cages or more, the optical system becomes very large.

In view of the above problems, the present invention provides a tilt detection head that has high resolution, a wide detection range, and is compact.

In order to solve the above problems, the tilt detection head of the present invention includes a light source that emits at least two substantially parallel beams with different emission angles, a beam splitter, a convex lens, and a light source that emits at least two substantially parallel beams with different emission angles. It comprises a position detection element and at least three mirrors disposed between the convex lens and the optical position detection element, and one of the mirrors is configured to reflect light twice. .

Operation With the above configuration, only one parallel light is first emitted and irradiated onto the object to be measured. The reflected light is reflected by a beam splitter, converged by a convex lens, and forms a focused spot on the optical position detection element. When this focused spot misses the optical position detection element, the light source is extinguished and another parallel beam is emitted. By doing so, it becomes possible to detect when the focused spot is incident on the optical position detection element. In this way, by sequentially emitting light from all the light sources, the detection range is expanded, and by using three mirrors and reflecting the light twice on one of them, it is possible to use a convex lens with a long focal length. It can be downsized without reducing detection resolution.

EXAMPLE Hereinafter, an example of the present invention will be explained based on FIGS. 1 and 2.

In FIG. 1, 1 is a first parallel light source, 2 is a second parallel light source, 3 is a first beam splitter, 4 is a second beam splitter, 16 is an object to be measured, 8 is a convex lens, 7, 8 ．．
9 is the first. The second and third mirrors 1o are optical position detection elements.

With such a configuration, the first. For example, if a semiconductor laser and a collimator lens are used as the second parallel light sources 1 and 2,
The beam irradiated onto the object to be measured 6 is usually 2 m x 6
It has an elliptical shape of approximately fi, and this head measures the average inclination within this area.

First, when the first parallel light source 1 emits light and the object to be measured 6 is inclined by θ from a preset reference plane, the reflected light has an inclination of 2θ and is reflected by the second beam splitter 4. and enters the convex lens 6. The incident light is converged by the convex lens 6, and the first . The light is reflected by the second and third mirrors 7.8.9 to form a focused spot on the optical position detection element 10. In this example, three mirrors? , 8.9 are used to bend the optical path, and one of the mirrors 7 reflects the light twice, so space can be used effectively.

Further, when the focused spot is off the optical position detection element 1o, the first parallel light source 1 can be extinguished and the second parallel light source 2 can be emitted instead, so that the detection range can be expanded.

The detection range expanded by this wider I'ffi configuration will be explained with reference to FIG. Let α be the difference between the emission angles of the two parallel beams 101 and 102, and perform optical adjustment so that the focused spot when the reflected light returns in the direction of the bisector of the emission angle is located at the origin of the optical position detection element 1o. Suppose that this is done. At this time, if the plane perpendicular to the bisector is taken as the basic plane, the first parallel light 101 is α/2° and the second parallel light 102 is α/2 with the object 6 tilted. The focused spot will be located at the origin. The detection range becomes i deg if a convex lens 6 with f=143 am is used. In order to eliminate overlap between the detection ranges of the two parallel beams 101 and 102, it is sufficient to set α=1dθq, and the detection range at this time is doubled to a total of 2 dogs.

The above explanation is about a method of expanding the detection range only in the -axis direction, but in order to further expand the detection range in the -axis direction, it is sufficient to add one more horizontal light source.

Also, in order to generate two parallel beams, we used a method of combining them with a beam splitter, but if we use a semiconductor laser with two light emitting points, it is possible to generate two parallel beams without a beam splitter. Needless to say.

Effects of the Invention As described in 2., the present invention is capable of emitting at least two parallel lights, and has at least three mirrors, one of which reflects the light twice. , it is possible to provide a tilt detection head that is compact, has high resolution, and has a wide detection range.

[Brief explanation of the drawing]

2r'J' is a (7?I) diagram of the tilt detection head in the embodiment of the present invention, FIG. 2 is an explanatory diagram thereof, and FIG. 3 is a configuration diagram of a conventional tilt detection head. 1... ...First parallel light source, 2...Second parallel light source, 4...Second beam splitter-1
6...Convex lens, 7,8.9...Mirror 1o...Optical position detection element.

Claims (1)

[Claims] A light source that emits at least two substantially parallel beams with different emission angles, a beam splitter, a convex lens, an optical position detection element, and at least three mirrors between the convex lens and the optical position detection element, A tilt detection head in which one of the mirrors reflects light twice.