JPS62106306A - Multi-wavelength interferometer - Google Patents

Abstract

PURPOSE:To enhance accuracy in matching in accordance with the requirement of a measuring object and to make it possible to measure both optical systems for visible light and infrared rays, by constituting the power source provided in a Fizeau interferometer of a plurality of light sources containing at least one visible light source and selecting the same using a selection means. CONSTITUTION:A semiconductor laser beam source 30 is provided in addition to a He-Ne laser beam source 1 and infrared rays emitted from the beam source 30 is allowed to be incident on a dichroic mirror 31 to be transmitted therethrough. Red beam emitted from the beam source 1 is allowed to be incident on a pinhole 3 through a condensing lens 2 to be incident on the mirror 31 in the same way while harmful beam is cut and reflected therefrom. Thereafter, two kinds of laser beams mixed by the mirror 31 are sent to a polarizing beam splitter 5 and one of reflected beams is emitted to the outside through a 1/4 wavelength plate 6, a half mirror 7 and a collimator lens 8. The other reflected beam is converted to an interference fringe by a visual field iris 18, a lens 19 and a rotary screen 21 and said interference fringe is again focused into an image on a TV camera 12 by zoom lenses 22, 23 and an image forming lens 24.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a Fizeau interferometer used for measuring optical components.

[Prior art] In recent years, interferometers have been widely used to inspect optical components.
Among these, the Fizeau type interferometer is mainly used.

As for the structure of such a Fizeau type interferometer, the structure shown in FIG. 5 can be shown as an example.

In the Fizeau interferometer shown in the figure, the laser beam emitted from the He-Ne laser 1, which is one light source, is transmitted through the condensing lens 2, the pinhole 3, and the total reflection mirror 4.
, a polarized beam slitter 5.17 Through an internal optical system comprising a wavelength plate 6, a half mirror 7, and a collimating lens 8, the parallel light is made to enter the test lens 9, and the transmitted light is transmitted by the reference spherical surface lO. reflected.

This reflected light is again divided into an alignment optical system and an interference optical system via the half mirror 7, and each is selected by a switching mirror 11, imaged by a TV camera 12, and observed by a TV monitor 13.

The alignment optical system includes a mirror 14, a screen 15, an objective lens 16, and a mirror 17, and the interference optical system includes a field stop 18, a lens 19, a motor 20, in addition to the 174 wavelength plate 6 and polarizing beam splitter 5. It consists of a rotating screen 21 which is rotated at a speed of 1, and zoom lenses 22 and 23, and 24 is an imaging lens.

[Problems to be Solved by the Invention] In the conventional interferometer having the configuration described above, since the wavelength is constant due to the laser as the light source, 1. For example, in the case of transmitted wavefront aberration measurement which is affected by the wavelength, This method has the disadvantage that aberrations occur due to the difference between the wavelength used by the lens to be tested and the wavelength of the interferometer, making accurate measurements impossible.

In addition, interferometers for non-visible light have drawbacks such as difficulty in measuring seven alignments of a lens to be tested and a long time required for measurement.

Therefore, the present invention was made by focusing on the above-mentioned drawbacks of the conventional Fizeau type interferometer, and it is possible to accurately measure the transmitted wavefront aberration of visible and non-visible optical systems without being affected by aberrations, and to The object of the present invention is to provide an interferometer that can perform alignment while using visible light when it is visible, and can perform measurements accurately and quickly.

Means for Solving Problem c] The present invention provides a Fizeau interferometer that includes a plurality of light sources including at least one light source of visible light, and means for selecting the plurality of light sources.

[Function] The present invention improves the adaptability and accuracy of measurement by selecting and using a light source that matches the measurement purpose from among a plurality of light sources, and also enables measurement of both visible and infrared optical systems by rotation. Alignment can be facilitated by using visible light as a guide light during infrared measurement.

[Example] Examples of the multi-wavelength interferometer according to the present invention will be described below with reference to the drawings.

(First example) FIG. 1 is a block diagram showing a first embodiment of the present invention.

In the figure, 30 is a semiconductor laser as another light source arranged in addition to the light source of the He-Ne laser 1, and the light beam He-Ne emitted from this semiconductor laser 30 is
By arranging a dichroic mirror 31 at a point where the emitted light from the laser 1 intersects with the light beam passing through the condensing lens 2 and pinhole 3, the emitted light from the He-Ne laser 1 is made to enter the dichroic mirror 31. The configuration is such that the light emitted from the semiconductor laser 30 can be incident on the polarizing beam splitter 5 via the dichroic mirror 31.

The rest of the structure is the same as that of the Fizeau type interferometer shown in FIG.

In the interferometer with the above configuration, the semiconductor laser 3
The infrared light emitted from the I(e-Me laser I) enters the dichroic mirror 31 and passes through it, while the red light emitted from the I(e-Me laser I) is reflected by the condenser lens 2.
The light is focused on a pinhole 3 disposed at the same position as the light emitting point of the semiconductor laser 30, harmful light is cut off, and enters a dichroic mirror 31 where it is reflected. Thus, the two types of laser beams mixed by the dichroic mirror 31 enter the polarizing beam splitter 5 and are reflected. Thereafter, the light is circularly polarized by the 174-wavelength plate 6, reflected by the half mirror 7, and turned into a beam by the collimator lens 8 and output to the outside. This light flux passes through the measurement optical system and the test optical system, is reflected,
Return along the same optical path again. This light beam is split into two by a half mirror 7, and the transmitted light is reflected by a mirror 14 and formed into an image on a screen 15. The image is re-imaged onto the TV camera 12 by forming a reduction optical system using the objective lens 16 and the imaging lens 24. At this time, the light beam is reflected by the mirror 17,
The switching mirror 11 is displaced to a position outside the optical path. Perform realignment of this luminous flux.

On the other hand, the light beam reflected by the half mirror 7 becomes linearly polarized by the quarter-wave plate 6, passes through the polarizing beam splitter 5, passes through the field stop 18, and is focused by the lens 19 on the rotating screen 21 as F interference fringes. imaged. This image is re-formed onto the TV camera 12 by a variable magnification optical system composed of zoom lenses 22.degree. 23 and an imaging lens 24.

At this time, the switching mirror 11 is located at the position shown and reflects the light beam.

The alignment image and interference image formed on the TV camera 12 are switched by moving the switching mirror 11 to the respective positions. The image is observed on the TV monitor 13.

According to the interferometer having such a configuration, the dichroic mirror 31 mixes the two lights, so there is little loss.
Since the optical parts do not require any moving parts, the accuracy can be easily managed and maintained.

(Second example) FIG. 2 is a block diagram showing a second embodiment of the present invention.

The interferometer according to this embodiment is constructed by disposing a half prism 33 in place of the dichroic mirror 31 in the interferometer configuration of the first embodiment, and the other configurations are completely the same as the first embodiment. If the same number exists, the explanation of the operation of each component 9 will be omitted.

However, especially in the case of such an embodiment, it is possible to prevent the occurrence of astigmatism due to transmission through the dichroic mirror 31, and there is an advantage that it can be constructed using general-purpose optical components.

In addition, as another embodiment, an embodiment may be mentioned in which a polarizing beam splitter 1, a non-polarizing beam splitter, or a half mirror is used instead of the half prism 33.

(Third example) FIG. 3 is a block diagram showing a third embodiment of the present invention.

This embodiment is constructed by disposing a mirror 34 in place of the dichroic mirror 31 and the half prism 33 in the configuration of the first embodiment and the second embodiment.

The other configurations are the same as those of the first embodiment, are given the same numbers, and descriptions of the configuration and operation will be omitted.

Therefore, depending on the purpose of measurement, it is possible to perform measurement without mixing by switching the laser beams of the @e-%@laser l and the semiconductor laser 30 using the mirror 34, which eliminates aberrations and losses and improves optical accuracy. It is possible to measure the improvement in

(Fourth example) FIG. 4 is a block diagram showing a fourth embodiment of the present invention.

The interferometer of this embodiment has the configuration shown in FIG.
This shows an embodiment in which a Ha--Ne laser 35 having a different wavelength from that of the -Ne laser 1 is additionally arranged.

The other components are the condenser lens 36 necessary for the He-He laser 35. The configuration other than the additional arrangement of the pin pole 37 and the half prism 38 is the same as that of the second embodiment shown in the second figure, and the same reference numerals are used to omit the explanation of the configuration and operation.

In the configuration, a semiconductor laser having a wavelength different from that of the semiconductor laser 30 may be used instead of the He-He laser 35, or a polarizing beam splitter 1 may be used instead of the half prism 33 as described in the explanation of the second embodiment. Examples may include using a non-polarizing beam splitter or a half mirror.

Furthermore, the embodiments in terms of the number of light sources are not limited to the embodiments shown in FIGS. 1 to 4, and of course, implementations in which three or more light sources are used as necessary are also possible.

[Effects of the Invention] As described above, the interferometer according to the present invention eliminates the influence of aberration due to wavelength when measuring transmitted wavefront aberration of not only visible optical systems but also non-visible optical systems, making it possible to perform accurate measurements. Become. Furthermore, by using visible light and performing alignment when it is not visible, measurements can be carried out quickly.

[Brief explanation of drawings]

1 to 4 are block diagrams showing first to fourth embodiments of the present invention, and FIG. 5 is a block diagram of a conventional Fizeau type movable meter. 1, 35---He-He laser 2.36... Converging lens 3.37... Pinhole 5... Modified beam splitter 6... Bow 74 Wave plate 7... Half mirror 8. ... Collimator lens 9 ... Test lens 10 ... Reference spherical surface 11 ... Switching mirror 12 ... TV camera 13 ... TV monitor 14 ... Mirror 15 ... - Screen 16 ... Objective lens 17...Mirror 18...Field stop 19...Lens 20...Motor 21...Rotating screen 22.23...Zoom lens 24...Imaging lens 30...Semiconductor laser 31... Gwikuro ink mirror 33... Half prism 34... Mirror patent issued by Olympus Optical Industry Co., Ltd. Figure 2 Figure 3 Figure 4 Figure 5 ) January 28, 1985 1. Indication of the case: Patent Application No. 245712 of 1985 2. Name of the invention Multi-wavelength interference Total 3. Person making the amendment/Relationship with 19 cases Patent applicant address Tokyo 2-43-2-4 Hatagaya, Shibuya-ku, Miyako, Agent 6, Subject of amendment 7, Contents of amendment +, 1) ``Beam through linter'' described on page 2, line 3 of the specification is replaced with ``beam splitter.'' -” is corrected. , 2) "Light flux He-" described on page 4, line 20 of the specification
Ne J is corrected as "luminous flux and He-NeJ." “1゜35” written on the 19th line of the page
-・-He-N e laser' r 1-He-N e
"Laser" is corrected. (5) Between the fourth line of page 12 of the specification and the fifth line of the same page [
35...Insert the gas laser.・, mark Figure 1 in the drawing is corrected as shown in the attached sheet. 8. List of attached documents

Claims (1)

[Claims] (1) A Fizeau-type interferometer comprising a plurality of light sources including at least one visible light source and a means for selecting the plurality of light sources.