JPH03220431A - Interferometer - Google Patents

Abstract

PURPOSE:To monitor the variation of the emissivity resulting from the temperature change of a detector arranged in a projecting direction and an interferometer itself by providing another detector at the remaining position where the incident light does not enter. CONSTITUTION:In this interferometer designed to separate a projecting light returning to the side of an incident light I from the incident light I, the projecting lights are generated at two points centering a semi-transparent mirror 1. Therefore, two detectors I, II are arranged at the two points, respectively. Moreover, another detector III (the temperature of which is particularly kept constant) is provided in a direction of an incident light II. Accordingly, since the detector III looks the interferometer and detectors I, II, the detector III can be utilized to monitor the variation of the emissivity as a result of the temperature change of these interferometer and detectors. If the variation of the emissivity detected by the detector III is rendered zero, the variation of the emissivity of the incident light I (light source) can be detected by the detector I. Further, the sum of the coefficient of variation of the detectors I and II can be detected by the detector III. Based on the detected value, the temperature of the interferometer and detectors I, II is controlled, or a measuring signal of a sample from the detector II is corrected.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a semi-transparent mirror, a fixed mirror system and a movable mirror system that reflect the light transmitted through the semi-transparent mirror and the reflected light toward a semi-M mirror, respectively. In particular, it relates to an interferometer suitable for use in Fourier transform infrared spectrophotometers.

[Conventional technology]

FIG. 6 shows the configuration of a conventional Michelson interferometer. In the figure, 1 is a semi-transparent mirror, 2 is a fixed mirror, and 3 is a movable mirror. In the conventionally well-known Michelson interferometer, as shown in FIG. 6, part of the input light and the output light enter and exit in the same direction. That is, the incident light is split into reflected light and transmitted light by the semi-transparent mirror 1, reflected by the fixed mirror 2 and the movable mirror 3, respectively, and then enters the semi-transparent mirror 1 again to form interference light. In such an interferometer, when using an interference signal called an interferogram generated by the difference between the optical path length on the fixed mirror 2 side and the optical path length on the movable mirror 3 side, half of the emitted light returns to the direction of the incident light. Since it is difficult to separate the emitted light, the remaining half of the emitted light is used for measurement. Furthermore, the light that returns in the direction of the incident light may have a negative effect on the light source and the like.

Apart from this point, according to the configuration shown in Fig. 6, when the detector is placed in the direction of the emitted light H, the light from the detector returns to the detector itself through the interferometer and becomes the signal light. This can cause fluctuations in the interferogram signal obtained from the detector. Therefore, by placing a slit or aperture between the interferometer and the detector, or by placing the sample in a slit or aperture-shaped sample holder, the light from the detector is incident on the interferometer. However, there is a possibility that the light from the detector hits the slit or aperture (or the slit or aperture-shaped sample holder) and bounces off, and enters the detector as well. For this reason, if there is a temperature fluctuation around the detector, or if there is a temperature fluctuation in the slit or aperture, this temperature fluctuation will cause the output fluctuation of the interferometer.

In order to avoid half of the emitted light returning to the direction of the incident light, which is a drawback of the conventional Michelson interferometer as described above, the present inventor proposed the method of
As shown in the figure, the fixed mirror 2 and the movable mirror 3 are composed of two mirrors, and the incident direction from the semi-transparent mirror 1 to each mirror 2.3 and the reflected light from each mirror 2.3 are reflected from the semi-transparent mirror 1. The measurement accuracy is improved by making it possible to separate and use the output light I that returns to the input light I side from the input light II without increasing the area of the semi-transparent mirror 1 by configuring it so that the incident direction is different from that of the semi-transparent mirror 1. We also proposed an interferometer that eliminates the negative effects of emitted light on the light source.

[Problem to be solved by the invention]

By the way, in the case where the output light I returning to the input light I side can be used for measurement as shown in FIG. 7, as shown in FIG. The incident light appears to enter from two places, the incident light I and the incident light H (in FIG. 8, the arrow indicates the interferometer viewed from the detector 2). In other words, from the detectors I and 2, light indicating their own temperature fluctuations is emitted in the direction of the incident lights 2 and H. Therefore, in the arrangement where the measurement light is incident from the incident direction (■), if the sensitivity of the detectors (■) and H has temperature dependence,
The incident direction (2) can be used to monitor and correct the temperature of these detectors 11 (11).

Therefore, the object of the invention is to provide two incident light directions and two
In an interferometer that has two emission light directions and separate incident and emission directions, it is possible to monitor emissivity fluctuations due to temperature changes in the detector placed in the emission direction and in the interferometer itself. An object of the present invention is to provide an interferometer capable of measuring accuracy.

Means for Solving the Two Problems] To that end, the interferometer of the present invention includes a semi-transparent mirror, a fixed mirror system that reflects the light transmitted through the semi-transparent mirror and the reflected light toward the semi-transparent mirror, and a movable mirror. In an interferometer, the direction of the incident light and the direction of the outgoing light are separated, and both the incoming light and the outgoing light can take two different positions.The position of the remaining incident light where the incoming light does not enter Place another detector in the direction of the emitted light! The present invention is characterized in that it is configured to be able to monitor changes in emissivity due to temperature changes of the detector and interferometer themselves.

[Effect]

In the interferometer of the present invention, another detector is placed at the position of the remaining incident light where the incident light does not enter, so the emissivity of the detector placed in the direction of the emitted light and the interferometer itself can be adjusted based on temperature changes. Changes can be monitored. therefore,
When the sensitivity of the detector placed in the direction of the emitted light is temperature dependent, the temperature is monitored by the other detector described above to control the temperature of the interferometer itself and the detector placed in the direction of the emitted light. Highly accurate measurements can be made by correcting the output.

〔Example〕

Hereinafter, the present invention will be described in detail with reference to the drawings.

FIG. 1 is a diagram showing the configuration of one embodiment of an interferometer according to the present invention, in which 1 is a semi-transparent mirror, 2 is a fixed mirror, and 3 is a movable mirror.

The configuration of the interferometer itself shown in FIG. 1 is the one proposed by the present inventor in Utility Model Application Publication No. 60-72511, as mentioned above, in which a fixed mirror 2 and a movable mirror 3 are arranged on two sides in a Michelson interferometer. Consisting of mirrors, from a semi-transparent mirror 1 to each mirror 2.
Direction of light towards 3 and each mirror 2.3 to semi-transparent mirror 1
The direction of the incident light is different from that of the incident light I, and the outgoing light that returns to the incident light I side is separated from the incident light I.

In this interferometer, since the emitted light is generated at two locations with the semi-transparent mirror 1 as the symmetrical surface, a detector I and a detector (2) are placed at each location. In addition, a third detector (2) is placed in the direction of the incident light (2) (see FIG. 8). Keep the temperature of the detector ■ especially constant. In such an arrangement, the detector (2) looks into the interferometer and the detectors (1) and (2). Therefore, detector (2) can be used to constantly monitor emissivity fluctuations due to these temperature changes. When the sample is measured by the detector I, the detector I can normally measure the fluctuation of the light from the light source coming from the direction of the incident light (I), which is the largest fluctuation factor in the measurement.

If the emissivity variation of incident light I is 1, the emissivity variation of detector I is DI%, the emissivity variation of detector The fluctuation rate is (11+D3), and the fluctuation value measured by the detector (■) is (D + + D2). If the emissivity fluctuation D3 of the detector ■ is set to zero, the incident light ■
(light source) emissivity fluctuation ■1 can be detected, and detector ■ can detect the total fluctuation rate (D,
-4-D2) can be detected (assuming that the interferometer itself does not fluctuate). Based on this detected value, the temperature of the interferometer itself and the detectors 1 and H may be controlled, or the sample measurement signal from the detector (2) may be corrected.

Note that the present invention is not limited to the above-mentioned interferometer shown in FIG. 7, but can be applied to any interferometer in which the direction of the incident light and the direction of the outgoing light are separated, and two positions are possible for both the incoming light and the outgoing light. . Examples of such interferometers are shown in FIGS. 2 to 5.

The interferometers in Figure 2 are J, F, James, R, S.
, 5ternberry”The Design of
0ptical Spectrometers p, 1
39 (Chapman and) fall, 196
9), two or three mirrors (corner cube mirrors) orthogonal to each other are used as the fixed mirror 2 and the movable mirror 3, and the light path passing through the fixed mirror 2 and the movable mirror 3 are set as the semi-transparent mirror 1. In order to make the optical paths passing through the same characteristics, a semi-transparent film 11 on the optical path of the incident light (1) and a semi-transparent film 12 on the optical path of the output light are separately deposited on the front and back sides of the crystal plate 10. In this case as well, as is clear from the drawing, there are two possible positions for the incident light: the incident light weight and H, and the positions for the emitted light are also possible for the emitted light ■ and ■. Similarly, put the light from the light source on one side, place the detector ■ on the other side, and
Detectors I and ■ are placed at the positions of the emitted light ■ and H, respectively.
The detector I can detect emissivity fluctuations of the incident light (light source), and the detector (2) can detect the fluctuation rate of the interferometer itself, the detectors (2) and H in total. Based on this detected value, the temperatures of the interferometer, detectors (1) and (2) can be controlled, or the sample measurement signal from the detector (2) can be corrected.

Furthermore, the interferometer shown in FIG.
Haseth “Fourier Transform”
Infrared 5pectroscopy1],
595 (John Wiley & 5ons,
(1986), which is a Michelson interferometer in which the incident light is shifted from perpendicular to the fixed mirror 2 and movable mirror 3, and the incident light and the outgoing light are separated. It is. In this case as well, as is clear from the drawing, there are two possible positions for the incident light, ml and ■, and the position of the output light is also possible for the output beams ■ and ■, which is the same as in Figure 1. , put the light from the light source on one side, place the detector ■ on the other side, and place the detectors ■ and ■ at the positions of the output lights I and H, respectively, and detect the incident light ■ (light source) by the detector I. It is possible to detect emissivity fluctuations in the interferometer itself and the total fluctuation rate of the detectors I and H using the detector (2). Based on this detected value, the temperature of the interferometer, detector I, (2) can be controlled, or the sample measurement signal from the detector (2) can be corrected.

Furthermore, the interferometer shown in Figure 4 was originally developed by the author of the application
This is one of the devices proposed in No. 91, and is a modification of the interferometer shown in FIG. 1 so that it is arranged three-dimensionally in space. The angle of the incident light I and the arrangement angles of the fixed mirror 2 and the movable mirror 3 are set so that the plane containing the incident light and reflected light on the movable mirror 3 forms a different plane from the plane containing the incident light and reflected light on the movable mirror 3. It is. In this case as well, as is clear from the drawing, the position of the incident light is the incident light I.
There are two possible positions: and , and the output light I
, Detector I and ■ are placed at the positions of ■, respectively, and detector 1
The variation in emissivity of the incident light (light, 1ii') can be detected by the detector (1), and the fluctuation rate of the interferometer itself and the total of the detectors I and H can be detected by the detector (2).

This detected value can thus be used to control the temperature of the interferometer, detectors (1) and (H), or to correct the sample measurement signal from the detector (2). Note that in other interferometers of the above-mentioned application, the detector m can be similarly arranged to achieve the same effect as in the case of FIG. 1.

Furthermore, the interferometer shown in FIG. is fixed mirror I5,
It is arranged so that it returns to the same position on the semi-transparent mirror 1 via the fixed mirror 6. Further, half of the incident light transmitted through the semi-transparent mirror 1 is arranged so as to return to the same position on the semi-transparent mirror 1 via the movable mirror 7 and the movable mirror I8. Both lights that have returned to the position of the semi-transparent mirror 1 interfere with each other on the front and back sides of the semi-transparent mirror 1, and are emitted in two directions, an output light (1) and an output light (2). As is clear from the figure, the optical path from semi-transparent mirror 1 to fixed mirror I5 and fixed mirror ■6 and the optical path from semi-transparent mirror 1 to movable mirror ■7 and movable mirror ■8 are parallel to each other in the same space. Since they are not on the same plane, even if there is a change in the refractive index due to a change in the atmosphere of the space on one side of the semi-transparent mirror 1, such as a change in temperature, this effect is automatically compensated for. It is an interferometer that can In this case as well, as is clear from the drawing, there are two possible positions for the incident light, i.e., I and H, and the positions for the emitted light are also possible for the emitted light ■ and ■. Similarly, put the light from the light source on one side, place the detector ■ on the other side, and
Detectors 11■ are placed at the positions of the emitted light I and ■, respectively,
The emissivity variation of the incident light I (light source) can be detected by the detector (2), and the variation rate of the interferometer itself and the total of the detectors T and a can be detected by the detector (2). Based on this detected value, it is possible to control the temperatures of the interferometer, detectors (2) and H, or to correct the sample measurement signal from the detector (2). In addition, in the Ike interferometer of the above-mentioned application, the same effect as in the case of FIG. 1 can be achieved by arranging the detector (2) in the same manner.

The above are examples of the present invention, and the present invention is not limited to these examples.The direction of the other incident light and the direction of the output light are separated, and both the input light and the output light are separated into two or more directions. Applicable to all positionable interferometers.

Effect of mouth opening] As is clear from the above explanation, in the present invention;
Since another detector is placed at the remaining incident light position where the incident light does not enter, it is possible to monitor emissivity fluctuations due to temperature changes of the detector placed in the direction of the output light and the interferometer itself. . Therefore, if the sensitivity of the detector placed in the direction of the emitted light is temperature dependent, the temperature of the interferometer itself and the detector placed in the direction of the emitted light can be controlled by monitoring the temperature with the other detector described above. or correct its output. Therefore, especially when using the interferometer of the present invention in a Fourier transform infrared spectrophotometer,
Measurement accuracy is improved.

[Brief explanation of drawings]

FIG. 1 is a diagram showing the configuration of one embodiment of the interferometer according to the present invention, FIGS. 2 to 5 are diagrams showing the configuration of another embodiment of the present invention, and FIG. FIG. 7 is a diagram showing the configuration of an interferometer, FIG. 7 is a diagram showing the configuration of another conventional interferometer, and FIG. 8 is a diagram for explaining the operation of the interferometer shown in FIG. 1... Semi-transparent mirror, 2.5.6... Fixed mirror, 3.7.8
... Moving mirror, 10... Crystal plate, 11... Semi-permeable membrane,
12...Semipermeable membrane applicant JEOL Ltd.

Claims (1)

[Claims] (1) A semi-transparent mirror, consisting of a fixed mirror system and a movable mirror system that reflect the light transmitted and reflected by the semi-transparent mirror toward the semi-transparent mirror, and the direction of the incident light and the direction of the emitted light are separated, and In an interferometer that can take two different positions for both the incident light and the output light, another detector is placed at the position of the remaining incident light where the incident light does not enter, and the detector is placed in the direction of the output light. and an interferometer configured to monitor emissivity fluctuations based on temperature changes of the interferometer itself.