JPH0634438A - High-resolution spectroscope - Google Patents

Abstract

PURPOSE:To obtain a high-resolution spectroscope which has a wide measure ment region, is simple, and can be controlled easily. CONSTITUTION:A polychrometer 9 is laid out at the irradiation side of a Fabry- perot interferometer 5 and a multi-channel detector 10 is provided at the irradiation side of the polychrometer. Then, it is adjusted so that the free spectrum region of the Fabry-perot interferometer is equal to the wavenumber width of one element of the multi-channel detector. In this state, the free spectrum region is divided into n parts, spectrum data for n times which are obtained by measurement for each are stored temporarily in a memory 14, all spectrum data are sent to an operation part 15 when the measurement for n times is completed, and they are synthesized there and outputted.

Description

Detailed Description of the Invention

[0001]

[0001]

[0002]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a high resolution spectroscopic device.

[0003]

[0002]

[0004]

2. Description of the Related Art As a conventional high-resolution spectroscopic device, there is, for example, one using a Fabry-Perot (hereinafter referred to as "FP") interferometer. This has a resolution of 10
^Although it is as high as about ⁶ , the free spectral range (hereinafter referred to as "FSR"), which is the measurable range width, is extremely narrow, and measurement in a wide wavelength range is impossible.

[0005]

As an improvement to this, for example, "High-resolution spectroscopic system by synchronous sweep of FP interferometer and double monochromator" shown on page 96 and after of "Spectral Research Vol. 34, No. 2 (1985)". There is. As is clear from the title of this device, a double monochromator is arranged on the emission side of the FP interferometer. As is well known, since the spectral transmittance characteristic of the FP interferometer has a periodic structure as shown in FIG. 6 (A), the transmission peak of the double monochromator is as shown in FIG. 6 (B). Match one of the peaks. As a result, when the light passes through the double monochromator, peaks other than the above-mentioned transmission peak among the peaks of the FP interferometer are removed. And these 2
While the transmission peaks of the two spectroscopes are matched with each other, both are synchronously swept at the same speed. As a result, sharp spectral characteristics without a periodic structure can be obtained as shown in FIG. Then, by devising the sweep method like a saw, it becomes possible to perform measurement in a wide wavelength range with high resolution.

[0006]

However, in the above example, it is actually very complicated to synchronize and the sweep is not constant.
The complexity of the synchronization control becomes more remarkable. Therefore, control must be performed with extremely high precision, and even if the spectroscopic device according to the present invention could be manufactured, extremely high precision is required for its assembly precision and alignment precision between each component. However, the work becomes complicated and expensive, and as a result, it cannot be put to practical use.

[0007]

Further, in general, it is impossible to obtain such a resolution with an ordinary spectroscope because a diffraction grating of 1 m or more must be used. And even if it were possible, it would be very dark. Further, in the Fourier spectroscope, the moving mirror of the interferometer must be stably moved for 1 m or more, which is an expensive and large-scale device. At present, the resolution of the FP interferometer has not been obtained.

[0008]

The present invention has been made in view of the above background, and an object thereof is to provide a high resolution, a wide measurable region, a simple device, control, etc., and a compact and bright high resolution. It is to provide a spectroscopic device.

[0009]

[0007]

[0010]

In order to achieve the above object, in a high resolution spectroscopic device according to the present invention, a Fabry-Perot interferometer, and a polychromator arranged on the exit side of the Fabry-Perot interferometer, A multichannel detector having an element width arranged on the exit side of the polychromator and having a spectral resolution width substantially equal to the free spectral region of the Fabry-Perot interferometer, and the free spectral region is divided into n and obtained by sweeping each. N
A means for storing the detection results of the batches and a means for synthesizing and outputting the detection results for the n times stored in the storing means are provided.

[0011]

[0008]

[0012]

FUNCTION The FSR of the FP interferometer is divided into n, and step sweep is performed to make a total of n measurements. Then, in the first measurement,
The data for each FSR interval on the spectrum data to be measured is taken out via the MCD and temporarily stored in the storage means. Then, in the second measurement, from the spectrum data obtained in the first measurement (FSR)
Since the spectrum data for each FSR interval at a position shifted by / n) is obtained, it is also extracted via the MCD and stored in the storage means. Then, the subsequent processing is performed up to the nth time. Then, n kinds of spectrum data will be stored in the storing means, and when the sweep processing of n times is completed, all the stored data are combined. The spectrum data obtained by synthesizing this is the one obtained by detecting the original spectrum data to be measured with a resolution of (FSR / n) step width, and the high resolution of the original spectrum to be measured. A spectrum is created. Then, the resolution is high resolution determined by the FP interferometer, and the measurement area is MC
It is a wide wavelength (wave number) region determined by D.

[0013]

[0009]

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A high resolution spectroscopic device according to the present invention will be described in detail below with reference to the accompanying drawings. FIG. 1 shows a first embodiment of the device according to the invention. As shown in the figure, the light emitted from the light source 1 to be measured is converted into a parallel light flux through the converging lens 2, the aperture 3 and the collimating lens 4, and then is made parallel to the optical axis to the FP interferometer 5. It is supposed to be incident. In this example, as the FP interferometer 5, one in which two semitransparent plane mirrors (etalon pair) 6a and 6b having high surface accuracy and high reflectance are arranged in parallel with each other is used. The scan driver 7 is connected to the plane mirror 6b so that the distance d between the plane mirrors 6a and 6b can be adjusted. The scan driver 7 is generally composed of a piezo element.

[0015]

Further, a converging lens 8 for coupling with a polychromator is arranged on the emission side of the FP interferometer 5, and a focal length position of the converging lens 8 is a polychromator which is a spectroscope for multi-channel detection. Place the meter 9,
Further, a multi-channel detector (hereinafter referred to as “MCD”) 10 is installed at the exit of the polychromator 9.

[0016]

The MCD 10 has a driver 11
Is connected to the controller 12 via. That is, the driver 11 operates the MCD 10 based on the control signal from the controller 12, reads the data detected by the MCD 10, and stores the data in the memory 14, which is a storage means in the computer 13, via the controller 12. There is. The controller 12 is also connected to the scan driver 7 that sweeps the plane mirror 6b of the FP interferometer 5 described above, and its drive is controlled by a control signal output from the controller 12.

[0017]

Further, in the computer 13, an arithmetic unit 15 for synthesizing the detection data stored in the memory 14 is added.
Is also equipped. In addition, the FSR and MC of the FP interferometer 5 described above
The wave number (wavelength decomposition) width per D element is adjusted and set to be equal.

[0018]

Next, the operation of the above-described device will be described. Prior to the description, the transmission characteristics of the FP interferometer will be described. The transmission characteristic TF is measured by an interferometer (a pair of semitransparent mirrors 6
Letting T be the transmittance (intensity) and R be the reflectance of the semi-transparent mirrors constituting a, 6b (etalon)) 5, TF = T ² / ((1-R) ² + 4Rsin ² δ).

[0019]

Here, δ is given by the following equation.

[0020]

[0015]

[0021]

## EQU1 ## δ = (π / λ) 2nd cos i−φ where n: refractive index of spacer material between etalons d: etalon interval i: incident angle φ: phase change of amplitude due to reflection inside etalon λ: wavelength Therefore, when δ = mπ, it becomes brighter. Here, m is a positive integer and represents the order of interference. Therefore, 2ndcos i = (m + (φ / π)) λ holds.

[0022]

Φ is assumed to be a constant and φ is set to 0. Further, as described above, in this example, since light is directly incident on the etalon, i is set to 0. Therefore, substituting those φ and i into the above equation yields 2nd = mλ. Therefore, when n or d is changed, λ changes for a constant m (order). In this example, d is changed by the scan driver 7 and n is constant in air (n = 1), so that 2d = mλ. Therefore, when d is fixed and the transmittance is viewed, light of wavelength (λ) corresponding to various orders (m) is transmitted, and the characteristics are as shown in FIG.

[0023]

In this example, the FSR of the FP interferometer 5 is divided into n, and step sweep is performed while gradually changing d from d1, d2 ... dn, and n measurements are performed. Then, assuming that the spectrum to be measured is as shown in FIG. 3A, as shown in FIG.
When the first measurement is performed at, the MCD 10 detects the site of the spectrum to be measured (black circle in the figure) corresponding to each peak value of the FP interferometer 5. At this time, the same figure (A),
As shown in (C), each FSR and MCD10 of the FP interferometer
Since each element of 1 is matched, each peak of the transmittance characteristics of the FP interferometer is located only somewhere in each element of the MCD. And that MCD10
The spectrum data detected by each element of is stored in the memory 14.

[0024]

Similarly, by performing the second measurement at the position d2, the spectrum data indicated by black triangles in the spectrum to be measured is read by the MCD10,
It is stored in the memory 14. In the following order, the sweep is repeated up to the nth time, and the MCD 10 is scanned for the setting of the FP interferometer 5 at each position di (i = 1 to n).
The seed spectrum data is stored in the memory 14.

[0025]

In this way, when the measurement of n times is completed, all spectrum data stored in the memory 14 are read out, and the arithmetic section 15 synthesizes (edits) them. This creates a high resolution spectrum that is close to the original spectrum to be measured. In this example, the resolution is a high resolution determined by the FP interferometer, and the measurement region is a wide wavelength (wave number) region determined by the MCD.

[0026]

When a comparison is made assuming that there is a diffraction grating spectroscope having the same resolution, the FP interferometer is used, so that it is bright and compact. Also, since a multi-channel detector is used, it is expected that the SN ratio will be improved due to multi-channel and advantage. Further, even if a Fourier spectrometer having the same resolution is present and compared, it is considered that the size is reduced and the SN ratio of the measurement data is rather improved.

[0027]

In the above embodiment, the FP interferometer 5 is used.
Although the example in which the condenser lens 8 is provided on the exit side of the FP interferometer is described above, the present invention is not limited to this. For example, as illustrated in FIG. (There is no collimator lens on the incident side)))
You may make it inject into 9 '. By doing so, an optical system for collimating a collimating lens or the like normally installed in the condenser lens 8 and the polychlormeter 9 becomes unnecessary, and the size of the apparatus can be further reduced.

[0028]

Further, in the above-mentioned embodiment and modification,
As the FP interferometer, the one composed of a pair of semi-transparent mirrors has been described, but in the present invention, as shown in FIG. 5, it comprises a predetermined spherical mirror pair (confocal etalon).
The confocal FP interferometer 5'may be used. When such an interferometer is used, the adjustment of the optical system can be performed in the parallel plane F
It is easier than the P interferometer.

[0029]

Further, the sweep is performed by the distance d as described above.
It is needless to say that the refractive index may be changed by inserting a high-pressure gas between the etalons and changing the gas pressure instead of changing the pressure.

[0030]

[0024]

[0031]

As described above, in the high-resolution spectroscopic device according to the present invention, the measurable wavelength range is a wide range defined by the MCD while exhibiting the high resolution of the FP interferometer. And becomes a high resolution spectroscopic device.
Moreover, since it is not necessary to synchronize the MCD side when sweeping the FP interferometer, various control meters are simple, the device is simple and compact, and the cost is low.

[0032]

The measurable range is from the ultraviolet range to the infrared range, and the versatility of the measurement is improved. As the field of use, various conditions are appropriately set to measure the gas absorption and the laser spectrum profile. Various measurements such as measurement, infrared spectrum, Raman scattering, Brillouin scattering are possible.

[Brief description of drawings]

FIG. 1 is a block diagram showing a preferred embodiment of a high resolution spectroscopic device according to the present invention.

FIG. 2 is a diagram showing a transmission characteristic of an FP interferometer.

FIG. 3 is a diagram for explaining an operation.

FIG. 4 is a block configuration diagram showing a modified example of the high-resolution spectroscopic device according to the present invention.

FIG. 5 is a block diagram showing still another modification of the high resolution spectroscopic device according to the present invention.

FIG. 6 is a diagram for explaining the operation principle of a conventional high resolution spectroscopic device.

[Explanation of symbols]

 5 FP interferometer 7 Scan driver 9 Polychromator 10 MCD 14 Memory (means for storing) 15 Computing unit (means for synthesizing and outputting detection results)

Claims (1)

[Claims] 1. A Fabry-Perot interferometer, a polychromator arranged on the exit side of the Fabry-Perot interferometer, and a spectrum arranged on the exit side of the polychromator and substantially equal to the free spectrum region of the Fabry-Perot interferometer. A multi-channel detector having an element width giving a resolution width, a means for storing the detection result for n times obtained by sweeping the free spectral region by n, and n times for the detection results stored in the storing means. High-resolution spectroscopic device having means for synthesizing and outputting the detection result of 1.