JPS6130724A - Interferometer - Google Patents

Abstract

PURPOSE:To repeatedly change the light path length of split beam without providing a reciprocal movement mechanism, by rotating the optical system having a plurality of reflective surfaces provided on the light path between a beam splitter and a fixed reflective mirror. CONSTITUTION:A beam splitter 11 for splitting incident beam IR into two luminous fluxes, a fixed reflective mirror 12 for reflecting the reflected beams from the beam splitter 11 to allow the same to be again incident to said splitter 11 and reflective mirrors 14, 15, arranged on a rotary stand 13, for reflecting transmitted beams to allow the same to be incident to a fixed reflective mirror 16 are provided. Two kinds of beams again incident to the splitter 11 from the fixed mirrors 15, 16 are interfered and the interfered beam IL is allowed to irradiate a specimen. When the rotary stand 13 is rotated around an axis O, the light path length between the splitter 11 and the fixed mirror 16 changes. By this method, the reciprocal movement of an optical system is unnecessary and the light path length of beam split by the splitter can be changed.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field 1] The present invention relates to a Michelson type interferometer that is most suitable for use in a Fourier transform infrared spectrophotometer.

[Prior Art] FIG. 5 shows a Michelson interferometer used in Fourier transform infrared spectroscopy, in which incident infrared light IR is split by a beam splitter 1. The infrared light reflected by the beam splitter 1 is reflected by the fixed reflecting mirror 2 and enters the beam splitter 1 again. The infrared light transmitted through the beam splitter 1 passes through the movable reflecting mirror 3.
The beam is reflected by the beam and enters the beam splitter again.

The infrared light reflected by the reflecting mirrors 2 and 3 interferes on the beam splitter 1, but the interference light enters the sample cell 4.
is detected by a detector (not shown). Here, on the optical path between the movable reflector 3 and the beam splitter 1, a position from the beam splitter 1 that is equal to the distance between the beam splitter 1 and the fixed reflector 2 is defined as a base point P, and the base point P If the distance from
If interference light is detected during this time, a so-called ink ferrogram having a peak at x=0 can be obtained.

Figure 6 shows another type of interferometer, in which the incident infrared light IR
is split by the beam splitter 5. The light reflected by the beam splitter 5 is reflected by a reflecting mirror 6 and enters a fixed reflection @7. The light reflected by the fixed reflecting mirror 7 is reflected by the reflecting mirror 6 and enters the beam splitter 5 again. The light that has passed through the beam splitter 5 is reflected by a fixed reflecting mirror 8 and enters the beam splitter 5 again. The lights reflected by the fixed reflecting mirrors 7 and 8 interfere on the beam splitter 5. The interference light is reflected by a reflecting mirror 9 and irradiated onto a sample cell (not shown).

Here, the beam splitter 51 reflecting mirror 6.9 is fixed on a rotary table 10, and rotated as a unit by rotating the rotary table 10 by a drive mechanism (not shown). Along with the rotation, the optical path length between the reflecting mirrors 6 and 7 changes, and by detecting the resulting interference light, an interferogram can be obtained.

[Problems to be Solved by the Invention] If the obtained ink ferrogram is subjected to Fourier transform processing, an infrared absorption spectrum of the sample can be obtained. However, in order to obtain an accurate spectrum by Fourier transform, In the configuration shown in FIG. 5, it is necessary to increase the moving distance of the movable reflecting mirror.

By the way, the reflecting surface of the moving reflector is always perpendicular to the direction of movement in order to maintain good coherence between the infrared light reflected by the fixed reflector and the infrared light reflected by the moving reflector. needs to be preserved.

When the moving distance is short, it is relatively easy to maintain the reflective surface vertically; however, as the distance increases, maintaining the verticality of the reflective surface becomes increasingly difficult.

Furthermore, in order to increase the distance, the bearing and drive mechanism that support the movable reflecting mirror must necessarily become large, and the interferometer itself must also become large. In addition, in an actual device, the movable reflecting mirror 3 is moved back and forth, but in this case, energy is required to stop and reverse the reflecting mirror, which has a considerable mass.
It becomes difficult to move the reflector back and forth at high speed.

In the configuration shown in FIG. 6, the optical path length is changed by a rotation mechanism. As a result, the bearing for the rotary table 10 is easier to manufacture with higher precision than a linear sliding bearing, and the optical path length changes depending on the rotation angle θ, but even if this θ is increased, it is difficult to manufacture the bearing. .

The difficulty does not increase. Furthermore, since the light incident on the fixed reflector 7 is the light reflected by the two mirrors of the beam splitter 5 and the anti-WM 6, even if the rotational axis accuracy of the rotary table 10 is poor, the light incident on the fixed reflector 7 will not reach the fixed reflector. The angle of incidence of light does not change, so it has little effect on measurements. however,
Even with the configuration shown in FIG. 6, in actual measurement conditions, the rotary table 1
0 is rotated back and forth, and a large amount of energy is required to stop, turn, and reverse the rotating table, which has a considerable mass. In addition, since the mirror 9 for extracting light to the outside of the interferometer is also rotating, the center position of the light reflected by the reflecting mirror 9 also moves in parallel as θ changes, and the subsequent optical path changes. Difficulties arise in configuration.

Therefore, a main object of the present invention is to provide an interferometer that can repeatedly change the length of one optical path divided by a beam splitter without the need for a reciprocating mechanism.

[Means for Solving the Problems] The interferometer based on the present invention splits light into two types of light by a beam splitter, reflects each of the split lights by a reflecting mirror, and collects the reflected light. An interferometer configured to cause interference on the beam splitter, which has a plurality of reflective surfaces in the optical path between the beam splitter and a reflecting mirror that reflects one of the lights split by the beam splitter. The optical system is characterized in that the optical system is configured to be rotated around an axis perpendicular to the axis of light incident on the optical system from the beam splitter.

[Example] Embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

In FIGS. 1A to 1C, incident light IR is split into two beams by a beam splitter 11. In FIG. The light reflected by the beam splitter 11 passes through a fixed reflecting mirror 12.
The beam is reflected by the beam splitter 11 and re-enters the beam splitter 11. The light transmitted through the beam splitter 11 is transmitted to the rotary table 1.
reflected by a reflector 14.15 placed on 3;
The light is incident on the fixed mirror 16. Here, the beam splitter 1
1 and the fixed mirror 161. :The incident light is parallel. The light reflected by the fixed mirror 16 is
It is reflected by the reflecting mirror 15, 14 and re-enters the beam splitter 11. The two types of light re-entering the beam splitter are interfered with each other, and the interference light IL is irradiated onto a sample hill (not shown).

In the configuration as described above, from the arrangement shown in FIG. 1(a),
When the rotary table 13 is rotated around an axis O perpendicular to the optical axis of the light incident on the reflecting mirror 14 to obtain the state shown in FIG. 1(b), the optical path length between the reflecting mirrors 14 and 15 is Although the optical path length is shortened, the optical path length between the beam splitter 11 and the reflecting mirror 14 and between the reflecting mirror 15 and the fixed mirror 16 are lengthened, and as a result, the optical path length between the beam splitter 11 and the fixed mirror 1 is increased.
The optical path length between 6 and 6 is increased. Furthermore, when the rotating table 13 rotates to the state shown in FIG. 1(C), the optical path length between the beam splitter 11 and the fixed mirror 16 is made longer. In this way, by rotating the rotary table 13 on which the two reflecting mirrors are mounted, the optical path length of one of the lights split by the beam splitter 11 is changed. Here, if the rotating table 13 is continuously rotated in the same direction without reciprocating, the states shown in FIGS. 1(a) to 1(C) can be repeatedly caused.

FIGS. 2(a) and 2(b) show other embodiments of the present invention, and the same structural elements as those in the embodiment of FIG. In this embodiment, the rotary table 13 rotates around a point O on the reflecting surface of the reflecting mirror 14, and the beam changes from the state shown in FIG. 2(a) to the state shown in FIG. 2(b). The optical path length between the splitter 11 and the fixed anti-fA mirror 16 is lengthened. In this embodiment as well, as in the embodiment shown in FIG. The optical path length of one of the lights divided by 11 can be changed periodically.

In the embodiment shown in FIGS. 3 and 4, the location of the fixed reflecting mirror 16 is different from the embodiment described above. In the embodiment of FIG. 3, the fixed reflector 16 is arranged side by side with another fixed reflector 12. Furthermore, in the embodiment shown in FIG. 4, the fixed reflector 16 is placed close to the beam splitter 11.

In the above embodiment, two reflecting mirrors are provided on the rotary table 13, but three or more reflecting mirrors may be provided.

[Effects] As detailed above, the interference device according to the present invention includes an optical system having a plurality of refractory surfaces on the optical path between a beam splitter and a fixed reflecting mirror, and the optical system is rotated. Because of this structure, it has all the advantages of the conventional rotary drive system, and furthermore, by continuously rotating the rotating reflector in the same direction, the beam can be split by a beam splitter without the need for reciprocating the reflector. The optical path length of the emitted light can be changed repeatedly. Therefore, the drive mechanism for changing the optical path length can be simplified.

[Brief explanation of drawings]

1 to 4 show one embodiment of the present invention, respectively.
FIGS. 5 and 6 are diagrams showing conventional interferometers. 11...Beam splitter 12.16...Fixed reflecting mirror 13...Rotary table 14.15...Reflecting mirror

Claims (1)

[Claims] In an interferometer configured to split light into two directions of light by a beam splitter, reflect each of the split lights by a reflecting mirror, and cause the reflected lights to interfere on the beam splitter. , an optical system having a plurality of reflective surfaces is arranged in the optical path between the beam splitter and a reflecting mirror that reflects one of the lights split by the beam splitter, and the optical system is connected from the beam splitter. An interferometer configured to rotate around an axis perpendicular to the axis of light incident on the optical system.