JPH0471453B2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] This invention is directed to a method in which a thin beam of light is incident on an optical system from a predetermined position at a predetermined angle, and the position of the emitted light is determined on a screen placed behind the optical system. The present invention relates to an optical system inspection device for measuring and inspecting an optical path within an optical system by ray tracing.

[Conventional technology]

Conventionally, there has been a device shown in FIG. 2 for inspecting the optical path of an optical system. In the figure, 1 is a laser light source, 2 is a telephoto optical system for collimating the laser light generated from the laser light source 1, 3 is an aperture, 4 is a test optical system, and 5 is for a test optical system 4. A first fine movement stage for adjusting the incident position and direction of the thin beam of light; 6 a pinhole for passing the output beam from the optical system 4 to be examined; 7 a pinhole for adjusting the position of the pinhole 6; This is the second fine movement table.

Next, the operation will be explained. The laser light emitted from the laser light source 1 is made into parallel light beams by the telephoto optical system 2, and a thin parallel light beam is taken out by the aperture 3.
When the fine adjustment table 5 is adjusted so that the light beam enters the optical system under test 4 from a predetermined position and at a predetermined angle, the light beam is repeatedly refracted according to Snell's law on each surface of the lens that constitutes the optical system under test 4 and advances. Transmit to the other side. The second fine movement table 7 is arranged so that the transmitted light passes through the pinhole 6.
The position of the pinhole 6 through which the light beam passes when the optical system 4 to be tested is not placed is the origin, and the scale of the second fine movement table 7 is read and compared with the value calculated by ray tracing. Can be inspected.

[Problem that the invention seeks to solve]

In a conventional optical system inspection device, even if a thin parallel beam is incident, the light that passes through the optical system to be inspected 4 is no longer a parallel beam due to the optical system to be inspected. However, there was a problem in that the beam became thick and the position detection accuracy was low. In terms of geometrical optics, if you make the aperture smaller and make the incident light beam narrower, you should be able to make the output light beam narrower, but in reality, the intensity of the light decreases, making it difficult to detect the position of the light beam, and the diffraction at the aperture makes the output light beam narrower. Improving accuracy is difficult because the light beam spreads out.

This invention was made to solve the above-mentioned problems.The intensity of the emitted light beam from the optical system to be tested is sufficient, and the center position of the emitted light beam can be clearly seen, and the position of the emitted light beam can be accurately determined. The objective is to obtain an optical system inspection device that can measure .

[Means for solving problems]

The optical system inspection apparatus according to the present invention is provided with an objective lens for a metallurgical microscope, a pinhole, and a diaphragm with a variable aperture diameter between a laser light source and an optical system to be inspected.

[Effect]

The objective lens in this invention condenses the laser beam and produces a concentric diffraction pattern with a bright center at the condensing point. If a pinhole about the diameter of the central bright part is placed at the focal point, a spherical wave centered at the focal point can be obtained. Since the aperture allows only a portion of this spherical wave to pass through, diffraction occurs due to the aperture. When the diffracted light is made incident on the optical system to be tested and the aperture of the diaphragm is adjusted, the light transmitted through the tested lens becomes a concentric diffraction pattern with a bright center, and the center position of the emitted light can be clearly seen.

〔Example〕

FIG. 1 is a configuration diagram of an optical system inspection apparatus showing an embodiment of the present invention. In FIG. 1, 1 is a laser light source, 3 is an aperture, 4 is an optical system to be inspected, and 5 is a first fine movement table. , 6 is a pinhole, 7 is a second fine movement table, 8
9 is an objective lens for a metallurgical microscope, and 9 is a pinhole that is placed at the focal point of the laser beam and allows only the bright part at the center to pass through.

Next, the operation will be explained. The laser beam emitted from the laser light source 1 is focused by the objective lens 8, and only the central bright part of the diffracted light by the objective lens 2 is passed through the pinhole 9 placed at the focal point of the laser beam. A spherical wave without spatial noise can be obtained that spreads radially from the hole position. The diaphragm 3 allows a portion of this spherical wave to pass through and enters the optical system to be tested 4, so that the transmitted light from the optical system to be tested 4 forms a concentric diffraction pattern at the position of the pinhole 6. This concentric pattern shows that when the aperture 3 is viewed from the pinhole 6 through the optical system 4 under test, the aperture 3
By adjusting the hole diameter of the diaphragm 3 depending on the number of Fresnel zones that fit into the hole, a bright spot can be created at the center of the concentric pattern. In this state, the position of the emitted light beam can be precisely measured by adjusting the second fine movement table 7 so that it passes through the bright spot or pinhole 6, and reading the scale of the second fine movement table 7. can. The optical system 4 to be inspected can be inspected by moving the first fine movement table 5 and measuring the position of the emitted light beam for each incident position and angle of incidence.

In the above embodiment, the pinhole 6 is used to detect the position of the emitted light beam, but the diffraction pattern may be projected onto a screen or the light-receiving surface of an image sensor.

〔Effect of the invention〕

As described above, according to the present invention, the center position of a light ray can be clearly seen by using diffraction, so ray tracing can be actually performed with high precision, and the axis of the lens, which was conventionally difficult to inspect based on imaging characteristics. It is now possible to inspect optical systems that include asymmetric elements such as misalignment and lens tilt. Furthermore, according to the present invention, since the measured values directly correspond to the ray tracing method used for optical design, the correspondence with the designed values is clear, and the optical system can be corrected if there is a deviation from the designed values. can be easily done.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing an optical system inspection device according to an embodiment of the present invention, and FIG. 2 is a diagram showing a conventional optical system inspection device. In the figure, 1 is a laser light source, 3 is an aperture, 4 is a test optical system, 5 is a first fine movement table, 6 and 9 are pinholes, 7 is a second fine movement table, and 8 is an objective lens for a metallurgical microscope. be. Note that the same or corresponding parts in the figures are indicated by the same reference numerals.

Claims (1)

[Claims] 1 A laser light source, an objective lens for a metallurgical microscope to focus the laser light emitted from this laser light source, a pinhole placed at the focal point of the laser light, and a part of the diverging laser light emitted from this pinhole. A diaphragm with a variable aperture diameter to pass through, a first fine movement stage for adjusting the position and angle of the optical system to be tested with respect to the divergent laser beam limited by the diaphragm, and a laser beam that has passed through the optical system to be tested. An optical system inspection device comprising: a pinhole attached to a second fine movement table for adjusting the position so that the center of the optical system passes through the pinhole.