JPH10332485A - Data processing method for emission spectrochemical analysis device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To simplify the constitution of an analysis device by omitting temperature adjustment and to eliminate the adverse effect of warm wind. SOLUTION: In the emission spectrochemical analysis device, two or more beams among the spectral light beams emitted from the main elements of a sample are made to be the reference wavelength light beams. Ranges W1 and W2 , wherein the light beams can be inputted, are set on an image sensor at every reference wavelength light. The reference wavelength light or the above described light is searched in the ranges W1 and W2 of the image sensor, which has received the spectral light of the sample or the spectral light, and the positions N1 and N2 are read out. A dispersion coefficient a [a = (λ2 -λ1 )/(N2 -N1 )], which indicates the displacement degree of the spectroscopic system of this emission spectrochemical analysis device, is computed. Then, by using this dispersion coefficient (a), an incident position of Nx of the spectrum light to be measured on the image sensor or a wavelength λx of the spectral light in correspondence with the position Nx on the image sensor is obtained by computation.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for processing data in an optical emission spectrometer using an image sensor as a photodetector, and more particularly, to an accurate incident position of spectral light using characteristics of an image sensor. Alternatively, it relates to a method of obtaining a wavelength.

[0002]

2. Description of the Related Art In an emission spectrometer, a sample emitted from a light emitting unit such as a light emitting stand or a plasma torch is guided to a diffraction grating through a condenser lens or an entrance slit. After spectroscopy into the spectrum light of the wavelength, the spectrum light of each wavelength is guided and detected by a photodetector such as a photomultiplier, thereby performing qualitative and quantitative analysis of the elements contained in the sample.

As the photodetector, there are a polychromator type using a number of photomultipliers and a monochromator type using a single photomultiplier as a photodetector. Some use image sensors arranged in a matrix.

[0004] The above-mentioned emission spectrometer is susceptible to the influence of temperature.
At a place where the optical system components and the interval between them slightly change, and where the spectrum light is received, these minute changes are accumulated and a considerable shift occurs in the incident position of the spectrum light.

[0005] In order to eliminate such a shift of the incident position, the conventional apparatus is provided with a heater and a hot air fan, and the internal temperature is kept constant by sending hot air into the inside.

[0006] This situation is the same for both types of emission spectrometers, and the polychromator type, monochromator type, and those using recent image sensors are easily affected by temperature. By adjusting the temperature as described above, the shift of the incident position of the spectrum light is eliminated.

[0007]

However, in the emission spectrometer, although the shift of the incident position of the spectrum light occurring before the photodetector is large enough to be corrected optically, the shift of the position shift is not significant. Since the physical dimensions are very small, a fine temperature adjustment is required to eliminate such a displacement.

For example, in a polychromator type apparatus, an exit slit is provided in front of each photomultiplier. The exit slit has a very narrow width of about 50 μm, and a specific spectrum within this width. In order to make light incident, it is necessary to perform high-precision temperature adjustment, and effective temperature adjustment is extremely difficult.

Further, in the conventional apparatus, since the inside is always kept at a higher temperature than the outside temperature by sending warm air into the inside, the apparatus used in a place where the outside temperature becomes high such as outdoors. In such a case, the temperature setting must be maintained at a fairly high level. In this case, the internal devices and parts are exposed to high temperatures, and the high temperature causes the characteristics of the devices and components to deteriorate, and the wear to occur at an early stage. And various adverse effects can be considered.

As described above, the temperature adjusting means in the conventional emission spectrometer is not easy to use for eliminating the shift of the incident position of the spectrum light, and may deteriorate the internal devices and components. There is.

Incidentally, an image sensor used as a photodetector in a recent emission spectroscopic analyzer is
Since a large number of light receiving elements are continuously arranged, spectral light can be continuously received in the wavelength direction over a wide range.
In this image sensor, even if the spectral light is shifted in the wavelength direction, the spectral light itself can be received only by changing the incident position.

The present invention focuses on the above-mentioned characteristics of an image sensor and performs data processing using the characteristics to correct the shift of the incident position caused by a temperature change. It is an object of the present invention to eliminate the need for temperature adjustment, simplify the configuration of the apparatus, and avoid adverse effects on parts and the like due to the warm air of the temperature adjustment.

[0013]

According to the present invention, there is provided a data processing method in an emission spectroscopic analyzer using an image sensor as a photodetector. After setting at least two of the spectral lights emitted by the light source as the reference wavelength light, the spectroscopy of the emission spectrometer is performed from the incident position of the set reference wavelength light or light corresponding to the reference wavelength light on the image sensor. It is characterized in that the degree of displacement of the system is calculated, and the incident position of the spectrum light to be measured on the image sensor is corrected based on the calculated degree of displacement of the spectral system.

According to a second aspect of the present invention, in the data processing method in an emission spectrometer using an image sensor as a photodetector, two or more of the spectral lights emitted from the main elements of the sample are used as reference wavelength light. Setting the range that can be incident on the image sensor for each reference wavelength light; and setting the range of the image sensor that receives the spectrum light obtained from the emission light of the sample or the light corresponding to the reference wavelength light. Searching for the reference wavelength light or the light and reading the positions N ₁ and N ₂ on the respective image sensors; and determining the wavelengths λ ₁ and λ _{2 of the} reference wavelength light or the measurement light and the image sensor. From the upper positions N ₁ and N ₂ , the dispersion coefficient a indicating the degree of shift of the spectral system of the emission spectrometer is calculated by the equation a = (λ ₂ −λ ₁ ) / (N ₂ −N ₁ ), And the incident position Nx on the image sensor or the incident position Nx on the image sensor based on the calculated dispersion coefficient a.
Calculating the wavelength λx of the spectrum light corresponding to the following equation: Nx = (λx−λ ₁ ) / a + N ₁ or λx = λ ₁ + a (Nx−N ₁ ).

[0015]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a configuration diagram of an emission spectrometer for use in carrying out the method of the present invention.

In FIG. 1, reference numeral 1 denotes a light emitting unit such as a light emitting stand or a plasma torch, 2 denotes a spectroscope, 3 denotes a condenser lens, 4 denotes an entrance slit, 5 denotes a diffraction grating, and 6 denotes a photodetector. Image sensor 7 is an image sensor 6
Is a data processing unit that processes data obtained from. The image sensor 6 is configured by continuously arranging a large number (for example, 1024) of pixels serving as light receiving elements.

In this apparatus, the temperature adjusting means as in the conventional apparatus is omitted, and the internal temperature changes according to the external temperature and the heat generated by the operation.

In the apparatus having the above structure, the radiated light of the sample generated by the light emitting section 1 enters the spectroscope 2 and is guided to the diffraction grating 5 through the condenser lens 3 and the entrance slit 4.
The light is split into spectral lights of each wavelength by the diffraction grating 5,
The light enters the image sensor 6. Data relating to spectral light in a wide wavelength range is obtained from the image sensor 6, and the data processing unit 7 processes this data,
Perform qualitative and quantitative analysis of elements contained in the sample.

Here, since the inside of the apparatus is not maintained at a constant temperature, the optical system components and the distance between the components slightly change according to the internal temperature. Although the incident position of the spectrum light is shifted in one of the wavelength directions, in the present invention, by processing the data by the method described below, it is possible to obtain the data excluding the influence of the temperature change.

The data processing method of the present invention will be described with reference to FIG. FIG. 2 is a waveform diagram for explaining the method of the present invention, wherein (A), (B), (C) and (D) correspond to different steps of the method. In this waveform diagram, the horizontal axis represents the wavelength or the position N on the image sensor 6, and the vertical axis represents the peak intensity P of the spectral light. Specifically, it is an array number of each pixel constituting the image sensor 6.

(Step S1) This is a preparation step. Prior to the analysis, the spectrum light of a reference wavelength (hereinafter referred to as reference wavelength light) is selected from among the spectrum lights emitted from the main elements of the sample to be analyzed. ) Is selected. Here, the main element of the sample refers to a known element in the sample, and a base element occupying most of the sample, an element added to the sample, or the like is used.

Since the wavelength of the reference wavelength light set in this manner is known, the position of incidence on the image sensor 6 can be expected to some extent. Therefore, if a range is set with a certain width in the wavelength direction on the image sensor 6, the reference wavelength light should surely enter the range. Therefore, as shown in FIG. 2A, such a range, that is, ranges W ₁ and W _{2 in} which the reference wavelength light can be incident is set on the image sensor 6 and stored. Since two or more reference wavelength lights are set, the range W ₁ ,
A plurality of W ₂ are set.

In the case of emission analysis, there are a plurality of wavelengths of the main element to be analyzed.
₁ and W ₂ are set and stored for each of these plural wavelengths.

(Step S 2) The sample is actually caused to emit light, and the spectrum light obtained from the emitted light is received by the image sensor 6. From the image sensor 6, as shown in FIG. 2B, data of spectrum light over a wide wavelength range is obtained.

(Step S 3) From the data of the incident spectrum light over the entire image sensor 6, the reference wavelength light of the main element of the sample is searched for in the ranges W ₁ and W ₂ on the image sensor 6. The search for the reference wavelength light is specifically performed as follows. That is, the incident position of the image sensor 6 of each reference wavelength light, but by shifting to one of the wavelength direction according to the internal temperature, the range W _1, W
₂ is set in anticipation of such a transition. Therefore, a peak of the reference wavelength light is always found in the ranges W ₁ and W ₂ . If found, positions N ₁ and N ₂ of the reference wavelength light on the image sensor 6 are read as shown in FIG.

[0026] In this case, each range W _1, W ₂ is less widely without, it is desirable to set the width to include only the reference wavelength light, range W _1, W 2 one or it in ₂ When the above-mentioned peak comes in, the peak intensity P may be compared to discriminate the reference wavelength light.

(Step S4) The above-mentioned step S3
The dispersion coefficient a is calculated from the positions N ₁ and N _{2 of} the reference wavelength light on the image sensor 6 and the wavelengths λ ₁ and λ _{2 of} each reference wavelength light obtained in the above. The dispersion coefficient a is a coefficient indicating the degree of displacement of the spectroscope 2 and the wavelengths λ ₁ and λ _{2 of the} two reference wavelength lights.
And the distance between the positions N ₁ and N ₂ of the two reference wavelength lights on the image sensor 6 and is obtained by the following equation (A).

A = (λ ₂ −λ ₁ ) / (N ₂ −N ₁ ) Equation (A) (Step S 5) The other spectral light emitted from the element to be measured is the same as the reference wavelength light. It is considered that they have shifted to the same degree. If the dispersion coefficient a is used, the incident position of the spectral light of a known wavelength should be known, and conversely, the wavelength of the spectral light incident on a required position on the image sensor 6 should be known.

For example, as shown in FIG. 2D, when it is desired to know the position Nx on the image sensor 6 where the spectrum light of the required wavelength λx is incident, the position Nx is expressed by the following equation (b). Can be obtained by

Nx = (λx−λ ₁ ) / a + N ₁ Expression (b) When it is desired to know the wavelength λx of the spectrum light incident on a required position Nx on the image sensor 6, (B)
Can be obtained by the following equation (c) obtained by transforming

Λx = λ ₁ + a (Nx−N ₁ ) Equation (3) In this manner, even if the incident position of the spectrum light to the image sensor is shifted in the wavelength direction due to the internal temperature, After performing the above-mentioned correction operation for each measurement, if the measurement operation is performed, the incident position of the desired spectrum light can be accurately found without being affected by the internal temperature, and the incident light can be incident on the required position. It is possible to accurately obtain the wavelength of the spectrum light being emitted.

In the above-described embodiment, the incident position of the required spectral light is obtained between the two reference wavelength lights, and the wavelength of the spectral light is obtained from the incident position. Is significantly deviated from the reference wavelength light, a reference wavelength light is separately set on the deviated side, a dispersion coefficient is calculated between the reference wavelength light and a reference wavelength light close thereto, and the dispersion coefficient is calculated. , The calculation shown in step S5 may be performed.

In the above embodiment, the dispersion coefficient a
Is calculated based on the reference wavelength light obtained by emitting the sample. In addition, the monochromatic light having the same wavelength as the reference wavelength light enters the spectroscope 2 without causing the sample to emit light. ,
The dispersion coefficient a may be calculated based on the monochromatic light.

Furthermore, in the above-described embodiment, the measurement accuracy is improved by re-calculating the dispersion coefficient a every time the analysis operation is performed. However, the dispersion coefficient a does not substantially change due to a change in temperature. If so, the following may be performed. That is, the dispersion coefficient a is calculated and stored by the above-described calculation method, and at each measurement, the required wavelength λx at which the element to be measured is generated using the stored dispersion coefficient a.
Alternatively, the incident position Nx on the image sensor 6 and the wavelength λx of the spectrum light incident on the predetermined position Nx on the image sensor 6 may be obtained. Then, the operation of each measurement operation is simplified, and the measurement time can be reduced.

[0035]

According to the method of the present invention, the shift of the incident position of the spectrum light caused by the temperature change can be corrected, and the influence of the internal temperature is eliminated, so that the temperature adjusting means can be omitted. Thus, the configuration of the device can be simplified.

Further, unlike the related art, since it is not necessary to maintain the inside of the apparatus at a higher temperature than the outside for temperature adjustment, it is possible to eliminate the adverse effects of the high temperature and to avoid deterioration of the internal devices and components.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of an emission spectrometer for use in carrying out a method of the present invention.

FIG. 2 is a waveform chart for explaining the method of the present invention.
(A), (B), (C), and (D) correspond to different steps of the method, respectively.

[Explanation of symbols]

Reference Signs List 1 light emitting unit, 5 diffraction grating, 6 image sensor, a dispersion coefficient, range on W ₁ , W ₂ image sensor, wavelength of λ ₁ , λ ₂ reference wavelength light, incident position on N ₁ , N ₂ image sensor

Claims (2)

[Claims] 1. A data processing method in an emission spectrometer using an image sensor as a photodetector, wherein at least two of spectral lights emitted from main elements of a sample are set as reference wavelength lights, The degree of displacement of the spectral system of the emission spectral analyzer is calculated from the set reference wavelength light or the incident position of the light corresponding to the reference wavelength light on the image sensor, and based on the calculated degree of displacement of the spectral system. A data processing method for an emission spectrometer, wherein an incident position of spectrum light to be measured on an image sensor is corrected. 2. A data processing method in an emission spectrometer using an image sensor as a photodetector, wherein two or more of spectral light emitted from main elements of a sample are used as reference wavelength light and can be incident. Setting a range on the image sensor for each reference wavelength light; and setting the reference within the range of the image sensor receiving the spectrum light obtained from the emission light of the sample or the light corresponding to the reference wavelength light. Searching for the wavelength light or the light and reading the positions N ₁ and N ₂ on the respective image sensors; the reference wavelength light or the wavelengths λ ₁ and λ _{2 of the} light and the position N ₁ on the image sensor; from N ₂ Prefecture, the dispersion coefficient a indicates the degree of displacement of the spectral system of the emission spectrophotometer, and calculating by = formula _{a (λ 2 -λ 1) /} (N 2 -N 1) Based on the calculated dispersion coefficient a, the incident position Nx on the image sensor to be measured spectrum light, or a wavelength [lambda] x of the spectral light corresponding to the incident position Nx on the image sensor, wherein Nx = (λx-λ ₁₎ / A + N ₁ or λx = λ ₁ + a (Nx−N ₁ ).