JPH10153544A - Wavelength calibration apparatus for spectroscopic analyzer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a calibration apparatus in which the correspondence of wavelength to the angle of rotation of a diffraction grating calibrated by a filter for wavelength calibration in an inspection at its shipment from a factory is stored, and the calibration treatment of the wavelength is executed at the start of an analysis so as to check the difference between the wavelength and that at its shipment, in which the abnormality of an optical system is displayed so as to judge the calibration to be bad when the difference is at a prescribed value or higher, and which avoids an erroneous measurement caused by performing the wavelength calibration automatically as it is, like in a conventional apparatus. SOLUTION: By an instruction from a CPU, the driving motor of a filter wheel 5 for wavelength calibration is turned, a filter 51 for wavelength calibration for transmitted light or a filter 52 for wavelength calibration for reflected light is set on an optical path, the driving motor of a diffraction grating 3 is turned, the peak wavelength of the absorbance of a sample whose data is known is searched while an angle θ with reference to the optical axis of the diffraction grating 3 is being changed continuously, and data on the relationship between the angle θ of the diffraction grating 3 and the wavelength is calibrated while four detected peak wavelengths are being compared with the angle of the diffraction grating. Then, the data on the relationship between the angle θof the diffraction grating 3 and the wavelength which are measured at its stipment from a factory is compared with data on a relationship measured at the start of an analysis. When the deviation between both is very small, the wavelength is calibrated. When the deviation is at a prescribed value or higher, its calibration is judged to be bad, and the abnormality of an apparatus is displayed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a spectrometer for analyzing the composition of a sample using an absorption spectrum, and more particularly to a wavelength calibrator for automatically calibrating its wavelength.

[0002]

A conventional spectroscopic analyzer is:
Although the wavelength was automatically calibrated each time the sample was measured, the measurement accuracy was increased.
If the instrument is used in a place where vibration is applied or where there is a change in ambient temperature, etc., the spectral system may be out of order, causing a shift in wavelength, and a shift that cannot be calibrated in the specified wavelength calibration process. is there. In such a case, if the measurement is performed by performing automatic calibration as it is, the accuracy of the wavelength is lacking, so that the measurement accuracy becomes poor, resulting in an erroneous measurement.

Accordingly, the present invention stores the correspondence between the rotation angle and the wavelength of the diffraction grating calibrated by the wavelength calibration filter at the time of factory shipment inspection, performs wavelength calibration processing at the start of analysis, and calculates the difference from the factory shipment. Is checked, if the difference is equal to or more than a predetermined value, it indicates that the spectroscopic system is abnormal and disables calibration, and it is made for the purpose of automatically calibrating and preventing incorrect measurement. is there.

[0004]

In order to achieve the above object, the present invention is configured as follows.

That is, in a spectrometer equipped with a wavelength calibration means for automatically calibrating a wavelength every time a sample is measured, a factory calibration value storage means for storing a calibration value calibrated at the time of factory shipment, A difference detecting means for comparing the calibrated calibration value with the calibration value at the time of shipment from the factory to detect a difference; and, when the difference is larger than a preset allowable value, displaying a device abnormality and making device calibration impossible to perform calibration. Means for calibrating a wavelength of a spectrometer.

[0006]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows a configuration diagram of a spectroscopic analyzer embodying the present invention. The spectrometer includes a light source 1, a reflecting mirror 2, a diffraction grating 3, a lens 4, a filter wheel 5 for wavelength calibration, a light detector 61 for reflected light, a light detector 62 for transmitted light, a sample cell 7, and a discharge valve 8. And a reflecting mirror 2, a diffraction grating 3, a lens 4, a wavelength calibration filter wheel 5, a sample cell 7, a reflected light photodetector 61, and a transmitted light photodetector 62 are respectively provided on the optical path of the light source 1. Deploy.

As shown in FIG. 2, a wavelength calibration filter wheel 5 transmits a measurement light beam split by the diffraction grating 3 and transmits the measurement light beam as a calibration light beam. Wavelength calibration filter 52, and measurement light passage holes 53, 54 through which the measurement light beam passes as it is.
Are arranged in the circumferential direction, and the wavelength calibration filter wheel 5 is rotated about the rotation shaft 55 to switch to the calibration light beam or the measurement light beam.

FIG. 3 is a block diagram of a wavelength calibration device for a spectrometer embodying the present invention. The wavelength calibration device is CP
Built-in memory (ROM / RAM) 10 in U9, I / O
A personal computer system in which a display device 12, an input device 13 such as a keyboard, and a printing device 14 such as a printer are connected via the board 11. The I / O board 11 includes a light source 1, a driving motor 3a for the diffraction grating 3, a sample cell. 7, transfer motor 7a, reflected light photodetector 61, transmitted light photodetector 6
2. Connect the drive motor 5a of the filter wheel 5 for wavelength calibration.

The wavelength calibration device of the spectrometer according to the present invention has the above-described configuration.
In response to a command from U9, the drive motor 5a of the wavelength calibration filter wheel 5 is rotated to transmit the wavelength calibration filter 51 for transmitted light.
Alternatively, the reflected light wavelength calibration filter 52 is set on the optical path.

Then, the drive motor 3a (stepping motor) of the diffraction grating 3 is rotated to continuously change the angle θ of the diffraction grating 3 with respect to the optical axis. FIG. 4 shows the relationship between the angle θ of the diffraction grating 3 and the wavelength λ of light. As shown in FIG.
When the angle θ of the diffraction grating 3 is changed, the wavelength λ of light split by the diffraction grating 3 also changes.

FIG. 5 shows an absorption spectrum of polystyrene used for a wavelength calibration filter. As shown in FIG. 5, polystyrene was 1143.6 nm, 1680.3 n.
m, 2164.9 nm and 2304.2 nm. In the wavelength calibration, the absorbance of the sample whose absorbance peak wavelength is known is measured, and the wavelength corresponding to the angle θ of the diffraction grating 3 is specified.
That is, while continuously changing the wavelength by changing the angle θ of the diffraction grating 3, the peak wavelength of the absorbance of the sample whose data is known is searched for. Then, while comparing the four peak wavelengths detected at this time with the angle θ of the diffraction grating 3, the graph of the relationship between the angle θ of the diffraction grating 3 and the wavelength λ of light shown in FIG. 4 is calibrated.

The wavelength calibration apparatus of the present invention uses a diffraction grating 3 measured at the time of factory shipment for four peak wavelengths shown in FIG.
The relationship data between the angle θ and the wavelength is compared with the relationship data measured at the start of the analysis. If the difference between the two is small, the calibration is performed. As the photodetector 61 for reflected light and the photodetector 62 for transmitted light, different detectors are used depending on the wavelength range to be measured. For 1,000 to 2,500 nm, a photoconductive detector of lead sulfide is used. However, for silicon photodetectors of 1100 nm or less, a diode or the like is used.

With reference to the flowchart shown in FIG. 6, the calibration process of the wavelength calibration device of the present invention will be described. In the wavelength calibration process, first, the transmitted light wavelength calibration filter 51 or the reflected light wavelength calibration filter 52 is set on the optical path (step 101), and an absorption spectrum measurement for wavelength calibration is performed (step 102). The measured absorption spectrum is subjected to a second differentiation process (step 103) to detect peak wavelengths, and the diffraction grating 3 corresponding to these peak wavelengths is detected.
.. Or related data thereof are specified (step 104). Then, it is determined whether or not the values of θ1, θ2,... Are within the range of the first predetermined widths α1, α2,. The wavelength calibration cannot be performed (step 106), and an apparatus error is displayed (step 10).
7). If within the range of the first predetermined widths α1, α2,..., The values of θ1, θ2,.
It is determined whether it is within the range of the second predetermined widths β1, β2,... Stored at 0 (step 108). If it is within the range, the wavelength calibration is not required (step 109), and the measurement waits (step 110). ). Second predetermined width β1, β2
If it is out of the range, the wavelength calibration is performed (step 11).
1) Go to step 110.

In a conventional wavelength calibration apparatus, even if a shift that cannot be completely calibrated by a predetermined wavelength calibration occurs, the wavelength is calibrated automatically and erroneous measurement is performed. As shown in the flow chart of FIG. 6, the wavelength calibration apparatus of the present invention uses the first predetermined values stored in the memory 10 at the factory shipment stage for the values of the drive angles θ1, θ2,. Width α1, α2
If it is out of the range, it is determined that the wavelength cannot be calibrated, and the apparatus abnormality is displayed. Therefore, when not using the device for a long time,
Since the failure of the device can be known before the measurement, an error such as measurement with poor measurement accuracy is prevented.

Further, the conventional wavelength calibration apparatus performs wavelength calibration for each sample measurement even for an apparatus whose accuracy is maintained at a level that does not require wavelength calibration. Spending unnecessarily. As shown in the flow chart of FIG. 6, the wavelength calibration apparatus sets the values of the drive angles θ1, θ2,.
The second predetermined width β1, stored in the memory 10 at the factory shipment stage,
If it is within the range of β2 ···, it is not necessary to calibrate the wavelength and wait for measurement. Therefore, the measurement of the absorption spectrum for wavelength calibration, which requires a lot of time, can be omitted, and the measurement efficiency can be improved.

Next, a description will be given of a wavelength calibrating device which executes the wavelength calibration at the end of the wavelength calibration. In this wavelength calibration device, the values of the drive angles θ1, θ2,... Of the diffraction grating 3 corresponding to the peak wavelength are stored in the memory 10 at the factory shipment stage in the second predetermined width β.
If it is within the range of 1, β2..., Wavelength calibration is not performed, but wavelength calibration must be performed immediately before the measurement is completed and the light source of the device is turned off.

Referring to the flowchart shown in FIG. 7, the calibration process of the wavelength calibration device will be described. In the wavelength calibration process, first, it is determined whether there is any remaining measurement sample (step 201). If there is no measurement sample, an absorption spectrum measurement for wavelength calibration is performed (step 20).
2). The measured absorption spectrum is subjected to second derivative processing (step 203) to detect peak wavelengths and to specify the driving angles θ1, θ2,... Of the diffraction grating 3 corresponding to these peak wavelengths or related data (step 203). 204). Next, wavelength calibration is performed (step 205), and the calibration value obtained by wavelength calibration is stored in the memory 10 (step 206).
The completion of calibration is displayed (step 207).

Since the conventional wavelength calibration apparatus performs the wavelength calibration for each measurement of the sample, it takes time to measure the absorption spectrum for the wavelength calibration every time. This wavelength calibration device always performs the wavelength calibration before the measurement is completed and the device is turned off.Therefore, the biggest factor that requires the wavelength calibration is to fix the device such as sticking or deterioration of each part of the device during storage. Eliminates problems caused by troubles while not in use, and eliminates the need for wavelength calibration processing that has been performed each time a sample is measured.

[0020]

According to the conventional wavelength calibration apparatus, even if there is a deviation that cannot be completely calibrated by the predetermined wavelength calibration, the calibration is automatically performed as it is and the measurement is performed, so that there is a problem in the reliability of the analysis data. The wavelength calibration device of the present invention stores the correspondence between the rotation angle and the wavelength of the diffraction grating calibrated by the wavelength calibration filter at the time of factory inspection, performs a wavelength calibration process at the start of analysis,
The difference from the time of shipment is checked, and if the difference is equal to or more than a predetermined value, the fact that the spectral system is abnormal is displayed and calibration is disabled. Therefore, according to the present invention, when a deviation that cannot be completely calibrated by the predetermined wavelength calibration occurs, there is no need to perform automatic calibration and perform erroneous measurement as in the related art, thereby improving the reliability of analysis data. .

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a spectroscopic analyzer of the present invention.

FIG. 2 is a schematic diagram of a wavelength calibration filter wheel.

FIG. 3 is a block diagram of a wavelength calibration device of the spectrometer according to the present invention.

FIG. 4 is a graph showing the relationship between the angle θ of the diffraction grating and the wavelength of light.

FIG. 5 is an absorption spectrum of polystyrene.

FIG. 6 is a flowchart of the wavelength calibration apparatus of the present invention.

FIG. 7 is a flowchart of a wavelength calibration apparatus that performs wavelength calibration at the end of the process.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Light source 2 Reflector 3 Diffraction grating 4 Lens 5 Wavelength calibration filter wheel 6 Photodetector 7 Sample cell 8 Discharge valve 9 CPU 10 Memory 11 I / O board 12 Display device 13 Input device 14 Printing device

Claims (1)

[Claims] 1. A spectroscopic analyzer comprising a wavelength calibration means for automatically calibrating a wavelength every time a sample is measured, a factory calibration value storage means for storing a calibration value calibrated at the time of shipment from a factory; A difference detecting means for comparing the calibrated calibration value with the factory calibration value to detect a difference; and, when the difference is larger than a preset allowable value, displaying a device error and responding to a device error that the calibration cannot be performed. Means for calibrating a wavelength of a spectroscopic analyzer.