JPS61172027A - Apparatus for inspecting prism - Google Patents

Abstract

PURPOSE:To make it possible to measure the angle of a prism at a high speed with high accuracy in a non-contact state by rough positional setting, by mounting a beam source emitting parallel beam, a prism to be inspected, a beam reflection means, a beam refraxing means, a beam reversal means and an angle detection means. CONSTITUTION:Parallel beam 21 emitted from an automatic collimator 11 is reflected by a prism 13 and subsequently reflected by the surface 20 of a prism 14 to be inspected and again reflected by the prism 13 to be returned to the collimator 11. Similarly, parallel beam 16 is reflected by the surface 19 of the prism 14 to be inspected and again reflected by a flat mirror 17. When the beam 18 reflected by the mirror 17 is allowed to be incident to a prism 21, the direction of beam is reversed and inclined by 2{(alpha-alpha')+beta}. If the angle to be measured of the prism 14 to be inspected is a desired angle alpha', that is, alpha=alpha', the beams 15, 22 are incident to the colimator 11 at an equal angle 2beta. If said angle is shifted from the desired angle alpha', the beams 15, 22 are shifted by the angle two times the shift amount alpha-alpha'. Therefore, if the angular difference of two beams is read, the shift of the prism 14 to be inspected from the desired angle can be detected.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a prism inspection device for measuring the angle of a prism.

BACKGROUND OF THE INVENTION As optical instruments and the like become more precise, their optical components are also required to be more precise. For this reason, it is desired that the angle inspection of prisms, which are often used in optical pickups, be made with higher precision and faster speed.

A conventional prism inspection device will be described below with reference to the drawings. FIG. 2 is a conceptual diagram of a rectangular prism inspection method. The light ray 2 emitted from the autocollimator 1 is reflected within the test prism 3, and the light ray 4 that emerges again has a refractive index of n when the apex angle of the test prism deviates from 90° by an angle α. , tilted by %4nα with respect to ray 2 (e.g., Optical Technology Measurement Handbook, Tayuki et al., 6
pp. 27-628, (1981)). By detecting this angle with the autocollimator 1, the angle of the prism can be easily inspected. However, in the above example, the angle is 90
Only when there is a slight deviation from 0, and for inspection of other angles, the method shown in Fig. 3 is used. A prism 7 is mounted, and the parallel light beams 8 and 9 from the autocollimator are respectively incident on the prism 6.7. By adjusting the position of the autocollimator so that the reflected light from the standard prism 6 overlaps with the incident light 8, the test prism 7
The angular deviation of the reflected light 1o from the incident light 9 is 2α, where α is the angular error with respect to the standard prism.

Problems to be Solved by the Invention However, in the above-described configuration, it is necessary to bring the prototype prism 6 and the test prism 7 into close contact with each other, and scratches, dirt, dust, etc. on the optical flat 5 may cause If the adhesion of either side becomes poor, errors occur in angle measurement, or if attention is paid to the adhesion of either side, there are problems such as poor workability.

In view of the above-mentioned problems, the present invention provides a prism inspection device that can measure the angular accuracy of a prism in a rough condition, non-contact, and at high speed without the need to place the prism in close contact with the prism to be inspected. .

Means for Solving the Problems In order to solve the above problems, the prism inspection apparatus of the present invention includes a light source that emits parallel light, and a test object whose surface including the angle to be measured is arranged substantially perpendicular to the parallel light. a detection prism, a mutually orthogonal light reflecting means provided to detect an angular error from the parallel light on the negative surface, and a portion of the parallel light reflected on another surface of the test lens that includes the angle to be measured. a beam bending means that reflects the parallel light and is tilted by a measured angle with respect to the parallel light, and a direction of a portion of the parallel light reflected by the beam bending means is reversed with respect to the direction in which the parallel light travels. The light beam reversing device is equipped with an additional beam reversing device, and an angle detecting device that detects the angle of each of the two beams reflected by the test prism.

Effect of the Invention With the above-described configuration, the present invention detects the angular deviation using reflected light when installing the prism to be inspected, without having to closely position it by, for example, placing it in close contact with an optical flat. By detecting with a beam bending means installed as a prototype and returning these measurement reflected lights in approximately the same direction, the angle measurement sensitivity is increased and the prisms are replaced one after another to achieve high speed and high accuracy. The angle of the prism can be measured at 0.0 Examples Examples of the present invention will now be described with reference to the drawings. FIG. 1 is a conceptual diagram of an embodiment of the present invention.

A portion 12 of the parallel light emitted from the autocollimator 11 is
After entering the right-angle prism 13 and being reflected twice inside, the light enters one surface 20 of the test prism 14 that includes the measurement angle α. The test prism 14 is placed with its surface 20 substantially perpendicular to the parallel light 12 from the autocollimator. However, if the deviation from the vertical plane is β, the light reflected by the surface 20 will be reflected twice again by the right-angle prism 13 and then return to the autocollimator 11. However, the light ray 15 will be inclined by an angle 2β with respect to the parallel light 12.

A part 16 of the parallel light emitted by the autocollimator 11 that moves in one direction is reflected by the other surface 19 of the test prism,
It is reflected again by the plane mirror 17.

The plane mirror 17 is installed so as to be tilted by the angle α of the prism with respect to the parallel light from the autocollimator 11 upon measurement. For example, when measuring a 60° prism, 60°
If the angle of the test prism 14 is α, the light ray 18 reflected by the 0-plane mirror 17, which is installed at an angle of 2(α
−α′) + β). However, reflected ray 1
6 and the reflected ray 18 have opposite inclinations. Therefore, when the light ray 18 is made incident on the roof-type prism 21, the direction of the light ray is reversed with respect to the parallel light 12, and is tilted by 2((α-α')+β).

The angle between the reflected light beam 15 and the reflected light beam 21 is detected by an autocollimator 11. Here, if the angle to be measured of the test prism 14 is the desired angle α', that is, "="', then the light ray 1
5. The light rays 21 enter the autocollimator 11 with equal angles 2β. On the other hand, if the measured angle of the test prism deviates from the desired angle d, the light rays 15 and 21 will deviate by an angle twice the deviation amount α-α'. Therefore, after installing the test prism 14, by reading the angular difference between the two light beams using the autocollimator 11, it is possible to detect the deviation of the test prism 14 from a desired angle.

Note that the right-angle prism 13 emits light in the same direction as the angle of incidence regardless of the angle at which it is attached, so that precision in attachment is not required.

On the other hand, in order to mount the mirror 17 at a desired angle with respect to the parallel light beam 12, place a prototype with the desired angle on the test prism 14, and conversely set it so that the amount of deviation α-α' becomes zero. The angle of the mirror 17 may be adjusted.

Effects of the Invention As described above, the present invention includes a light source that emits parallel light, a test prism, a light beam reflecting means for reflecting light in order to measure the inclination of one surface of the test prism, and the other surface of the test prism. a beam bending means installed at a desired angle so as to return the reflected beam to its original position for measuring the inclination of the surface;
By providing a beam reversing means for reversing the light with respect to parallel light and an angle detecting means for detecting the angle of the reflected light from both surfaces of the test prism, the angle of the test prism can be adjusted without contact. , it is possible to perform high-speed, high-precision measurements without worrying about the installation angle of the test prism.

[Brief explanation of drawings]

FIG. 1 is a diagram showing the concept of a prism inspection apparatus in an embodiment of the present invention, and FIGS. 2 and 3 are diagrams showing the concept of a conventional prism inspection method. 11...Autocollimator, 13...
Right angle prism, 14...Test prism, 17.
...Flat mirror, 21...Roof type prism. Name of agent: Patent attorney Toshio Nakao and 1 other person No. 1
Figure 2

Claims (2)

[Claims] (1) A light source that emits parallel light, a test prism whose one surface including the angle to be measured is arranged substantially perpendicular to the parallel light, and a part of the parallel light reflected to one surface of the test prism. a beam reflecting means orthogonal to each other that causes the reflected light to enter the prism and returns the reflected light substantially toward the light source; and a part of the parallel light reflected by another surface of the test prism that includes the angle to be measured, and converts the parallel light into the parallel light. ray bending means tilted by the angle to be measured; and ray reversing means for reversing the direction of a part of the parallel light reflected by the light ray bending means with respect to the traveling direction of the parallel light. and angle detection means for detecting each angle of a light beam reflected by two surfaces including the angle to be measured of the prism to be inspected. (2) A prism inspection device according to claim 1, characterized in that a light source that emits parallel light and an angle detection means are integrated to form an autocollimator.