JP2016142527A - Fourier transform type spectrophotometer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a Fourier transform type spectrophotometer with which it is possible to always excellently control the posture of a fixed mirror and control the movement speed of a movable mirror.SOLUTION: A Fourier transform type spectrophotometer comprises: a main interferometer provided with an infrared light source 2, a beam splitter 5, a movable mirror 7a, and a fixed mirror 6a and generating the interference light of an infrared ray emitted from the infrared light source 2; and a control interferometer including a laser beam source 8, a beam splitter 5, a movable mirror 7a, and a fixed mirror 6a and generating the interference light of a laser beam emitted from the laser beam source 8. The mixed mirror 6a is provided with a sensor for detecting the posture of the fixed mirror 6a, and the posture of the fixed mirror 6a is controlled on the basis of the detection signal of this sensor. The movable mirror 7a is provided with a sensor for detecting the movement speed of the movable mirror 7a, and the movement speed of the movable mirror 7a is controlled on the basis of this sensor.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a Fourier transform spectrophotometer.

  In the Fourier transform infrared spectrophotometer (FTIR), infrared interference light whose amplitude changes with time is generated by an interferometer typified by a Michelson interferometer including a beam splitter, a fixed mirror, a moving mirror, and the like. The sample is irradiated with the infrared interference light, and the transmitted light or reflected light is detected as an interferogram (hereinafter referred to as “IFG”). The transmission or reflection IFG is subjected to a Fourier transform process to obtain a spectrum with the wave number (or wavelength) on the horizontal axis and the intensity (absorbance or transmittance, etc.) on the vertical axis. Then, qualitative analysis or quantitative analysis of the sample is performed from the peak wavelength, peak intensity, etc. of this spectrum.

  In general, an interferometer in FTIR includes a control interferometer for generating a signal for IFG data sampling in addition to a main interferometer for obtaining IFG. The control interferometer includes a monochromatic light source (laser light source), a beam splitter, a fixed mirror, a moving mirror, etc. common to the main interferometer, and generates laser interference light for obtaining an interference fringe signal. The laser interference light is extracted from the optical path by a mirror inserted in the optical path of the infrared interference light and introduced into the photodetector. When the moving mirror moves at a constant speed, the intensity of the laser interference light is detected as a sine wave having a constant frequency, that is, a laser light interference fringe signal. A pulse signal for data sampling is generated based on the interference fringe signal.

  In order to perform qualitative analysis and quantitative analysis with high accuracy, it is important to acquire accurate and reproducible spectral data. For that purpose, the positional relationship between the movable mirror and the fixed mirror, the movable mirror and the fixed mirror relative to the reference plane, and so on. It is necessary to move the movable mirror at a constant speed while maintaining the position and posture of the lens at a constant. Therefore, in the conventional FTIR, the position and posture (tilt) of the fixed mirror are adjusted, and the posture and speed of the movable mirror are controlled using a signal obtained by the photodetector of the control interferometer. .

  In the conventional FTIR, in order to control the relative positional relationship between the fixed mirror and the movable mirror, a method of adjusting the tilt of the fixed mirror using the interference state of the laser beam in the control interferometer is used, which is called a dynamic alignment method. (See Patent Document 1, etc.). In this method, a photodiode in which a light receiving surface is divided into four by two axes (horizontal axis and vertical axis) orthogonal to each other is usually used as a photodetector for detecting laser interference light in a control interferometer. Here, of the four light receiving units, one light receiving unit is the reference unit R, the light receiving unit adjacent to the reference unit R in the horizontal direction is the horizontal unit H, and the light receiving unit adjacent to the reference unit R in the vertical direction. A signal obtained from the reference unit R is a reference signal Sr, a signal obtained from the horizontal unit H is a horizontal signal Sh, and a signal obtained from the vertical unit V is a vertical signal Sv.

  When there is a difference in optical path length within the beam cross section of the laser interference light, a phase difference occurs between the reference signal Sr, the horizontal signal Sh, and the vertical signal Sv. Therefore, when driving the movable mirror, the control unit has a constant phase difference (ΔRH) between the reference signal Sr and the horizontal signal Sh and a phase difference (ΔRV) between the reference signal Sr and the vertical signal Sv. As described above, a drive voltage is applied to the piezoelectric element mounted on the fixed mirror to compensate for the tilt of the fixed mirror. Thereby, the positional relationship between the mirror surface of the movable mirror and the mirror surface of the fixed mirror is maintained constant.

  On the other hand, the movable mirror is driven at a constant speed by feedback control using laser interference light in a control interferometer (see Patent Document 2, etc.). That is, when the moving mirror is moved, the control unit adds the signals respectively obtained by the four light receiving units of the photodiode, and calculates the moving speed Vc of the moving mirror from the frequency of the added signal. Then, a difference between the moving speed Vc and a predetermined target speed V0, that is, a speed error (Vc−V0) is obtained, and this speed error is fed back to the voltage applied to the motor that drives the moving mirror. Thereby, the movable mirror can be driven with high accuracy.

Japanese Patent Laid-Open No. 02-253103 JP 2009-139352 A

  In the conventional FTIR, the interference fringe signal obtained by the light detector of the control interferometer is processed as a fringe signal having amplitudes in the plus and minus directions from the reference potential, and this fringe signal is used to control the tilt of the fixed mirror and the movable mirror. Used for feedback control. That is, the phase difference (ΔRH and ΔRV) is obtained from the difference in timing of the rising zero cross (at the time of rising from the reference potential) of the reference signal Sr, the horizontal signal Sh, and the vertical signal Sv that are fringe signals, and the tilt of the fixed mirror is controlled. Also, by measuring the time from the rising zero cross of the added signal consisting of the fringe signal to the next rising zero cross, the time when the moving mirror moves by the distance of the optical path length difference corresponding to one wavelength of the laser is obtained and moved Find the moving speed of the mirror. However, such a configuration has the following problems.

One of the moving mirror driving devices used in the FTIR interferometer is a linear driving device composed of a voice coil and a magnet. In this linear drive device, the movable mirror is moved along the linear guide by the electromagnetic force generated by the current flowing through the voice coil and the magnetic field generated by the magnet. The moving speed of the moving mirror is adjusted by changing the magnitude of the voltage applied to the voice coil.
In such a device, the Coulomb friction (sliding friction) between the movable mirror and the linear guide increases due to deterioration over time, and as a result, the portion of the movable mirror that contacts the linear guide moves differently from the rest. Or a delay in response to the movement of the entire moving mirror. Since Coulomb friction cannot be predicted or detected, the attitude control of the fixed mirror and the movement control of the moving mirror are not necessarily optimally performed only by the phase difference and moving speed obtained at the zero cross timing of the fringe signal. This contributes to a decrease in the accuracy of the measurement itself.

In particular, when the moving mirror is moved at a low speed, the problem becomes obvious. Specifically, since the occurrence interval of the zero cross timing becomes longer, only the control set at the zero cross timing is continuously performed, and the virtually no control time increases.
Further, even if the fixed mirror can be maintained in a constant posture, the relative positional relationship between the fixed mirror and the movable mirror changes when the posture of the movable mirror changes. However, conventionally, since the posture of the movable mirror is not directly detected, it is impossible to cope with the above case.

  The problem to be solved by the present invention is that the attitude control of the fixed mirror and the control of the moving speed of the movable mirror can always be performed well, and the relative positional relationship between the fixed mirror and the movable mirror is kept constant. It is to provide a Fourier transform spectrophotometer that can be used.

The Fourier transform spectrophotometer according to the present invention made to solve the above problems is
A main interferometer that includes a multi-wavelength light source, a beam splitter, a movable mirror, and a fixed mirror, and generates multi-wavelength light interference light that is interference light of multi-wavelength light emitted from the multi-wavelength light source;
A Fourier transform spectrophotometer comprising: a monochromatic light source, the beam splitter, the moving mirror, and the fixed mirror, and a control interferometer that generates monochromatic light interference light that is interference light of the monochromatic light emitted from the monochromatic light source. In total
a) a movable mirror speed / attitude detection unit having a sensor attached to the movable mirror for detecting the movement speed of the movable mirror and a sensor for detecting the attitude of the movable mirror;
b) a fixed mirror posture control means for controlling the posture of the fixed mirror based on the detection result of the moving mirror speed posture detection unit;
c) moving mirror speed control means for controlling the moving speed of the moving mirror based on the detection result of the moving mirror speed posture detection unit;
It is characterized by providing.

The Fourier transform spectrophotometer according to the present invention further includes a fixed mirror posture detection unit having a sensor for detecting the posture of the fixed mirror,
The fixed mirror posture control means controls the posture of the fixed mirror based on the detection results of the fixed mirror posture detector and the moving mirror speed posture detector;
The moving mirror speed control means may control the moving speed of the moving mirror based on detection results of the fixed mirror attitude detection unit and the movable mirror speed attitude detection unit.

The movable mirror speed / attitude detection unit and the fixed mirror attitude detection unit can be composed of sensors such as a three-axis acceleration sensor, an angular velocity sensor, and a PSD (Position Sensitive Detector) sensor, and an arithmetic processing unit that processes the detection signal of the sensor. .
The sensor for detecting the moving speed of the moving mirror and the sensor for detecting the attitude of the moving mirror included in the moving mirror speed / attitude detection unit may be used as one sensor or as different sensors. . The sensor may be directly attached to the fixed mirror or the movable mirror, or may be attached to a member such as a support unit that moves integrally with the fixed mirror or the movable mirror. In addition, the sensor for detecting the posture of the fixed mirror may be provided in a part away from the fixed mirror. The arithmetic processing unit may be installed in a fixed mirror or a movable mirror, or may be installed in a location different from the fixed mirror or the movable mirror in the Fourier transform spectrophotometer. Further, a personal computer or the like connected to the Fourier transform type spectrophotometer by wire or wireless may function as the arithmetic processing unit. When the entire fixed mirror posture detection unit is attached to the fixed mirror, or when the entire movable mirror velocity posture detection unit is attached to the movable mirror, the MEMS (Micro Electro Mechanical) in which the sensor and the arithmetic processing circuit are integrated on a single substrate. Systems) may be used as a fixed mirror attitude detector and a moving mirror speed attitude detector.

  In the Fourier transform type spectrophotometer, the sample is irradiated with the multi-wavelength light interference light generated by the main interferometer, the transmitted light or reflected light is detected as IFG, and the transmitted or reflected IFG is subjected to Fourier transform processing. , Get the spectrum. Further, a signal for sampling the IFG data is obtained from the detection signal of the monochromatic light interference light generated by the control interference light. In the present invention, the fixed mirror posture, the movable mirror posture and the moving speed are obtained from the detection signals of the fixed mirror posture detection unit and the movable mirror speed posture detection unit different from the detection signal of the monochromatic interference light. Attitude control and moving mirror speed control are performed. In particular, the posture of the fixed mirror is controlled based on the detection results of the fixed mirror posture detection unit and the movable mirror speed posture detection unit, and the movement of the movable mirror is based on the detection results of the fixed mirror posture detection unit and the movable mirror speed posture detection unit. In the configuration for controlling the speed, the relative positional relationship and posture of the fixed mirror and the movable mirror and the speed of the movable mirror can be accurately controlled.

  In this case, the fixed mirror attitude control means and the moving mirror speed control means are the detection signals of the monochromatic interference light used for controlling the relative positional relationship between the fixed mirror and the moving mirror in the conventional Fourier transform spectrophotometer. If the control signal of the fixed mirror and the speed of the movable mirror are controlled by using the detection signals of the movable mirror posture detection unit and the fixed mirror posture detection unit, which are the characteristic configuration of the present invention, the control accuracy is further improved. improves.

  According to the Fourier transform spectrophotometer of the present invention, the posture of the fixed mirror, the posture of the movable mirror, and the moving speed can be detected at any timing without being restricted by the zero cross timing. In addition, the attitude control of the fixed mirror and the speed control of the moving mirror can be performed satisfactorily, so that the relative positional relationship between the fixed mirror and the moving mirror is kept constant, the speed of the moving mirror is kept constant, and fixed. It becomes possible to stabilize the control when step-scanning the movable mirror while maintaining the relative distance from the mirror.

1 is a schematic configuration diagram of an FTIR optical system according to a first embodiment of the present invention. FIG. The block diagram of the principal part of a control / processing system. The figure which shows the relationship between a fixed mirror and a movable mirror sensor, and the relationship between a movable mirror and a movable mirror sensor. The figure which shows the relationship of the phase difference calculated | required from the detection signal and sensor signal of a fringe signal and a laser interference light. The block diagram of the principal part of the control and processing system of FTIR which concerns on 2nd Example of this invention. The block diagram of the principal part of the control and processing system of FTIR which concerns on the modification of this invention.

Specific embodiments of the present invention will be described below with reference to the accompanying drawings.
FIG. 1 is a schematic configuration diagram of an FTIR optical system according to a first embodiment of the present invention. In FIG. 1, in an interferometer chamber 1, a main interferometer composed of an infrared light source 2, a condensing mirror 3, a collimator mirror 4, a beam splitter 5, a fixed mirror portion 6, and a movable mirror portion 7, and a laser light source 8, a control interferometer including a laser mirror 9, a beam splitter 5, a fixed mirror unit 6, and a movable mirror unit 7 is disposed. The fixed mirror section 6 includes a fixed mirror 6a, a support base 6b that supports the fixed mirror 6a, and a piezoelectric element 6c for adjusting the attitude of the fixed mirror 6a attached to the fixed mirror 6a (shown only in FIG. 2). It is configured. The piezoelectric element 6c adjusts the inclination (posture) of the fixed mirror 6a with respect to the X axis by driving the fixed mirror 6a in the rotation direction about the Z axis and the rotation direction about the Y axis. The movable mirror unit 7 includes a movable mirror 7a, a linear motor 7b composed of a voice coil and a magnet, and a linear guide 7c (shown only in FIG. 3). The movable mirror 7a reciprocates in the arrow M direction along the linear guide 7c by an electromagnetic force generated by applying a voltage to the voice coil.

  The main interferometer generates infrared interference light for measuring the spectrum of the sample 14 in the sample chamber 13 installed outside the interferometer chamber 1. That is, the infrared light emitted from the infrared light source 2 is applied to the beam splitter 5 through the condensing mirror 3 and the collimator mirror 4, and is split by the beam splitter 5 into two directions of the fixed mirror 6 and the movable mirror 7. The The lights reflected by the fixed mirror 6 and the movable mirror 7 are recombined by the beam splitter 5 and sent to the optical path toward the parabolic mirror 12. At the time of measurement, since the movable mirror 7 reciprocates in the direction of the arrow M, the combined light becomes interference light whose amplitude changes with time. The light collected by the parabolic mirror 12 is irradiated into the sample chamber 13, and the light that has passed through the sample 14 disposed in the sample chamber 13 is condensed by the ellipsoidal mirror 15 onto the infrared light detector 16. The

  On the other hand, the control interferometer generates laser interference light for obtaining an interference fringe signal. That is, the light emitted from the laser light source 8 is applied to the beam splitter 5 through the laser mirror 9 and is transmitted to the parabolic mirror 12 as interference light like infrared light. The laser interference light travels as a light beam having a very small diameter, is reflected by the laser mirror 10 inserted in the optical path, and is introduced into the laser detector 11. The laser detector 11 is a four-divided photodiode in which the light receiving surface is divided into four by two axes orthogonal to each other, and signals obtained by the four light receiving units are output in parallel. In a signal generation circuit (not shown), a pulse signal for sampling the light reception signal G1 for the infrared interference light is generated from the light reception signal of the laser detector 11, that is, the laser interference light signal G2.

  In addition to data sampling, the laser interference light signal G2 is used for attitude control of the fixed mirror 6a by the dynamic alignment method and speed control of the movable mirror 7a by feedback control based on the monitored moving speed.

  That is, as shown in FIG. 2, the signals G2 respectively obtained by the four light receiving units in the laser detector 11 are input to the arithmetic processing unit 20, and the arithmetic processing unit 20 is, as described above, of the four light receiving units. Of the reference signal Sr and the horizontal signal Sh with respect to the reference signal Sr obtained from a certain light receiving unit, the horizontal signal Sh and the vertical signal Sv obtained from the light receiving unit adjacent to the light receiving unit in the horizontal direction and the vertical direction, respectively. And a signal corresponding to the phase difference (ΔRH) between the reference signal Sr and the vertical signal Sv. The fixed mirror attitude control unit 21 generates a control signal such that the two phase differences ΔRH and ΔRV respectively match the target value of the phase difference given from the control amount setting unit 26. And the attitude | position of the fixed mirror 6a is adjusted by driving the piezoelectric element 6c via the drive part 22. FIG.

  On the other hand, the signal G2 obtained by each of the four light receiving units in the laser detector 11 is also input to the arithmetic processing unit 23, and the arithmetic processing unit 23 adds up all the signals obtained from the four light receiving units to obtain an interference fringe signal. Ask for. The moving mirror speed control unit 24 calculates the moving speed Vc of the moving mirror 7a from the frequency (period) of the interference fringe signal. Then, a difference between the moving speed Vc and a predetermined speed target value V0, that is, a speed error is obtained, and a transfer function determined by an interferometer control amount given from the control amount setting unit 26 is applied to the speed error. To calculate the feedback control amount. Then, by driving the linear motor 7b via the drive unit 25, the moving speed of the movable mirror 7a is kept constant.

  In order to keep the posture of the fixed mirror 6a properly and to keep the moving speed of the movable mirror 7a accurately and constant, the phase differences ΔRH and ΔRV reflect the actual inclination of the fixed mirror 6a. is important. Similarly, it is important that the moving speed Vc reflects the actual moving speed of the moving mirror 7a. In the FTIR of the present embodiment, sensors for detecting the posture of the fixed mirror 6a and the moving speed of the movable mirror 7a in real time are attached to the fixed mirror 6a and the movable mirror 7a, and the detection signals of these sensors are converted into the arithmetic processing unit 20 and Each is input to the arithmetic processing unit 23.

  That is, as shown in FIG. 3, the fixed mirror sensor 31 for detecting the inclination of the fixed mirror 6a is attached to the side surface of the fixed mirror 6a. A movable mirror sensor 32 for detecting the inclination of the movable mirror 7a and the moving speed of the movable mirror 7a is mounted on the side surface of the movable mirror 7a. As the fixed mirror sensor 31 and the movable mirror sensor 32, for example, a three-axis acceleration sensor is used. Since the triaxial acceleration sensor can measure the acceleration in the three directions of the XYZ axes with one device, it can directly obtain angle information, that is, information on the attitude of the fixed mirror 6a and the attitude of the movable mirror 7a.

  As the fixed mirror sensor 31 and the movable mirror sensor 32, an angular velocity sensor, a PSD sensor, or the like can be used in addition to the three-axis acceleration sensor. Further, the fixed mirror sensor 31 and the movable mirror sensor 32 are not limited to a single sensor, and may be composed of a plurality of sensors. When the fixed mirror sensor 31 and the movable mirror sensor 32 are composed of a plurality of sensors, the detection accuracy can be improved by installing the plurality of sensors in different parts. When the fixed mirror sensor 31 and the movable mirror sensor 32 are composed of a plurality of sensors, they may all be composed of the same type of sensor, or may be combined with different types of sensors. The fixed mirror sensor 31 and the movable mirror sensor 32 may be the same type of sensor or different types of sensors.

  Signals from the fixed mirror sensor 31 and the movable mirror sensor 32 are always input to the arithmetic processing units 20 and 23. Receiving the signal from the fixed mirror sensor 31, the arithmetic processing unit 20 processes this signal to obtain signals (ΔRH ′, ΔRV ′) corresponding to the phase difference (ΔRH) and the phase difference (ΔRV). When these signals are different from the phase difference obtained from the signals obtained by the four light receiving units of the laser detector 11, the fixed mirror attitude control unit 21 calculates the two newly obtained phase differences ΔRH ′, Control signals are generated such that ΔRV ′ matches the target value of the phase difference given from the control amount setting unit 26.

  Similarly, the arithmetic processing unit 23 that has received the signal from the movable mirror sensor 32 processes this signal to obtain the moving speed Vc ′ of the movable mirror. When the moving speed is different from the moving speed Vc obtained from the signals obtained by the four light receiving units of the laser detector 11, the moving mirror speed control unit 24 sets the moving speed Vc ′ and the target value V0. The difference is obtained, and the feedback control amount is calculated by applying a transfer function determined by the interferometer control amount given from the control amount setting unit 26 to this speed error.

  For example, (a) in FIG. 4 is obtained by removing the DC component from the fringe signal, (b) is a signal indicating a phase difference determined by the dynamic alignment method, and (c) is a signal of the fixed mirror 6a obtained by the fixed mirror sensor 31. A signal representing the tilt or a signal representing the tilt of the movable mirror 7a obtained by the movable mirror sensor 32 is shown. In FIG. 4A, arrows indicate the zero cross timing of the fringe signal. Although the falling zero cross timing is adopted here, the rising zero cross timing may be used. Further, both rising and falling zero cross timings may be used.

  In the conventional dynamic alignment method, signals respectively obtained by the four light receiving units of the laser detector 11 are input to the arithmetic processing units 20 and 23. The arithmetic processing units 20 and 23 process these signals to obtain a fringe signal, obtain a phase difference from the zero cross timing of the fringe signal, and obtain an inclination of the fixed mirror 6a and a moving speed of the movable mirror 7a from the phase difference. The control signal of the fixed mirror 6a obtained from the phase difference and the feedback control amount of the movable mirror 7a are held until the next zero cross timing ((b) in FIG. 4).

  On the other hand, the detection signals of the fixed mirror sensor 31 and the movable mirror sensor 32 are both input to the arithmetic processing units 20 and 23, and the arithmetic processing units 20 and 23 continuously process these signals regardless of the zero cross timing. Then, the attitude of the fixed mirror 6a and the attitude and moving speed of the movable mirror 7a are obtained (FIG. 4C). Therefore, in the FTIR of this embodiment, the attitude control of the fixed mirror 6a and the constant speed control of the movable mirror 7a are performed based on the optimal control amount at any time, not limited to the zero cross timing, and the spectrum is accurate and has good reproducibility. Data can be acquired. In particular, in this embodiment, since the attitude control of the fixed mirror a is performed using both the signal of the fixed mirror sensor 31 and the signal of the movable mirror sensor 32, the relative positional relationship between the fixed mirror 6a and the movable mirror 7a is constant. Can be maintained. Similarly, since the speed control of the movable mirror 7a is performed using both the signal of the fixed mirror sensor 31 and the signal of the movable mirror sensor 32, the accuracy of the speed control of the movable mirror 7a is improved.

  In the above-described embodiment, the posture of the fixed mirror 6a is controlled by using the phase difference obtained from the signals obtained by the four light receiving units of the laser detector 11 and is obtained from the signal of the fixed mirror sensor 31. When the phase difference is different from the phase difference obtained from the signals obtained by the four light receiving units of the laser detector 11, the phase difference obtained from the signal of the fixed mirror sensor 31 is used. The reverse is also acceptable. That is, normally, the attitude of the fixed mirror 31 is controlled based on the phase difference obtained from the signal of the fixed mirror sensor 31, and the phase difference obtained from the signals obtained from the four light receiving units of the laser detector 11 at the zero cross timing is fixed. If the phase difference is different from the phase difference obtained from the signal from the mirror sensor 31, the control amount may be corrected using the phase difference obtained from the signals obtained from the four light receiving portions of the laser detector 11. The same applies to the movement control of the movable mirror 7a.

  In the above-described embodiment, the posture control of the fixed mirror 6a and the movement control of the movable mirror 7a are performed using both the signal from the laser detector 11 and the signals from the fixed mirror sensor 31 and the movable mirror sensor 32. However, the signal from the laser detector 11 is used as a data sampling signal (interference fringe signal), and only the signals from the fixed mirror sensor 31 and the movable mirror sensor 32 are used to control the attitude of the fixed mirror 6a and the movable mirror 7a. It may be used as a signal for speed control. FIG. 5 shows a block diagram of the main part of the control / processing system of this embodiment.

Furthermore, instead of always using both the signal from the laser detector 11 and the signals from the fixed mirror sensor 31 and the moving mirror sensor 32, the posture control of the fixed mirror 6a and the movement control of the moving mirror 7a are not performed, but the moving mirror 7a. The weights of the signal G2 from the laser detector 11, the signals from the fixed mirror sensor 31 and the movable mirror sensor 32 may be changed according to the state of the movable mirror, such as the position and speed of. Further, the user may be able to freely set the weight.
In this case, as shown in FIG. 6, one arithmetic processing unit 40 is provided instead of the arithmetic processing unit 20 and the arithmetic processing unit 23, and signals from the fixed mirror sensor 31 and the movable mirror sensor 32 are provided in the arithmetic processing unit 40. In addition, the signal G2 from the laser detector is input, and the arithmetic processing unit 40 calculates a control amount corresponding to the weight of each signal and outputs it to the fixed mirror attitude control unit 21 and the moving mirror speed control unit 24. It is good to configure.

  Furthermore, the present invention is not limited to a Fourier transform infrared spectrophotometer, but can also be applied to a Fourier transform visible / ultraviolet spectrophotometer using visible light or ultraviolet light as multiwavelength light.

DESCRIPTION OF SYMBOLS 2 ... Infrared light source 3 ... Condensing mirror 4 ... Collimator mirror 5 ... Beam splitter 6 ... Fixed mirror part 6a ... Fixed mirror 6b ... Support stand 6c ... Piezoelectric element 7 ... Moving mirror part 7a ... Moving mirror 7b ... Linear motor 7c ... Linear guide 8 ... laser light source 9, 10 ... laser mirror 11 ... laser detector 12 ... parabolic mirror 13 ... sample chamber 14 ... sample 15 ... ellipsoidal mirror 16 ... infrared light detectors 20, 23, 40 ... calculation Processing unit 21 ... Fixed mirror posture control unit 22, 25 ... Drive unit 24 ... Moving mirror speed control unit 26 ... Control amount setting unit 31 ... Fixed mirror sensor 32 ... Moving mirror sensor

Claims (4)

A main interferometer that includes a multi-wavelength light source, a beam splitter, a movable mirror, and a fixed mirror, and generates multi-wavelength light interference light that is interference light of multi-wavelength light emitted from the multi-wavelength light source;
A Fourier transform spectrophotometer comprising: a monochromatic light source, the beam splitter, the moving mirror, and the fixed mirror, and a control interferometer that generates monochromatic light interference light that is interference light of the monochromatic light emitted from the monochromatic light source. In total
a) a movable mirror speed / attitude detection unit having a sensor attached to the movable mirror for detecting the movement speed of the movable mirror and a sensor for detecting the attitude of the movable mirror;
b) a fixed mirror posture control means for controlling the posture of the fixed mirror based on the detection result of the moving mirror speed posture detection unit;
c) moving mirror speed control means for controlling the moving speed of the moving mirror based on the detection result of the moving mirror speed posture detection unit;
A Fourier transform spectrophotometer characterized by comprising: In the Fourier transform type spectrophotometer according to claim 1,
Furthermore, a fixed mirror posture detection unit having a sensor for detecting the posture of the fixed mirror,
The fixed mirror posture control means controls the posture of the fixed mirror based on the detection results of the fixed mirror posture detector and the moving mirror speed posture detector;
The movable mirror speed control means controls the movement speed of the movable mirror based on the detection results of the fixed mirror posture detection unit and the movable mirror speed posture detection unit;
A Fourier transform spectrophotometer characterized by comprising: Comprising a detector for the monochromatic interference light,
The Fourier transform spectrophotometer according to claim 1 or 2, wherein the fixed mirror attitude control means controls the attitude of the fixed mirror with reference to a detection signal of the monochromatic interference light. Comprising a detector for the monochromatic interference light,
3. The Fourier transform spectrophotometer according to claim 1, wherein the moving mirror speed control means controls the moving speed of the moving mirror with reference to the detection signal of the monochromatic interference light.

Images