JP3140297B2 - Spectrometer - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a recently proposed spectroscopic analyzer for analyzing components such as grains by a spectroscopic analysis technique. A light source that irradiates the measuring beam to the unit, a spectral unit that splits the measuring beam transmitted through or reflected from the measuring unit, and an array-type light receiving element that receives the split measuring beam. Provided, between the light source and the spectroscopic means on the optical path of the measurement light beam, provided with a wavelength calibration unit having a calibration filter that transmits the measurement light beam to a calibration light beam having a pair of wavelength peaks, Perform wavelength calibration
The present invention relates to a spectroscopic analyzer that performs spectroscopic analysis after the measurement.

[0002]

2. Description of the Related Art This type of spectroscopic analyzer employs a structure for obtaining the amount of components such as grains based on a calibration equation.
It is very important to recognize which frequency light is received by which element of the array type light receiving element. Therefore, the present inventors, for example, perform wavelength calibration each time a sample is measured, and confirm the correspondence between the frequency of the received light and the element number of the array-type light receiving element, and perform calibration while performing the detection. is suggesting. Conventionally, when calibration is performed in such a configuration, a stable state of the light source and the optical system is ensured by taking measures such as leaving the power supply for a certain period of time or stabilizing the optical system for the purpose of stabilizing the optical system or not turning off the power. (Guaranteed). That is, conventionally, warm-up for several hours has been performed manually after power-on.

[0003]

However, in a component analyzer which can be easily used on site, it is difficult to make the warm-up time uniform because environmental conditions such as temperature are not constant. Furthermore, if a relatively long warm-up is performed every time a sample is measured as described above, it takes a long time, which is not practical as an apparatus. Accordingly, an object of the present invention is to provide a spectroscopic analyzer capable of performing calibration for wavelength calibration in a short time in accordance with environmental conditions.

[0004]

In order to achieve this object, a spectroscopic analyzer according to the present invention is characterized in that a peak for detecting a temporal change in a position change of a wavelength peak in a calibration light beam on an array type light receiving element. There is provided a position detecting means, and a wavelength calibration confirming means for judging that the wavelength calibration has been completed when the temporal change of the position becomes equal to or less than a predetermined value. The operation and effect are as follows.

[0005]

That is, the spectroscopic analyzer of the present invention comprises a peak position detecting means and a wavelength calibration recognizing means. For example, after the light source is turned on, the peak position detecting means converts the time-dependent calibration light beam on the array type light receiving element. A certain wavelength peak position is detected, and the position change state of this wavelength peak position is grasped. Then, when this position change becomes equal to or less than a predetermined value, the wavelength calibration recognition unit determines that the stability of the optical system has been achieved. Therefore, the problem of stabilization, which is affected by environmental conditions such as temperature depending on the place where the spectroscopic analyzer is mounted, can be rationally solved. Therefore, conventionally, for example, warming-up, which takes 2 hours uniformly (it takes a long time to take the safety side inevitably), becomes 10 to 4 hours.
It can be performed in the environment of about 0 minutes in accordance with the surrounding environment.

[0006]

Therefore, in the spectrometer of the present invention, the wavelength calibration, which most affects the accuracy of the spectroscopic analysis, is performed in a reliable and short time, so that the measurement accuracy is much higher than that of the conventional spectrometer. As well as improving reliability and operability, it can be improved. In general, when the target of the spectroscopic analysis is the component analysis, the second derivative of the spectrum of the transmitted light or the reflected light at a plurality of (three to four) specific wavelengths is represented by a calibration equation for determining the component analysis amount. Although the basic data is used, the accuracy of the basic data can be confirmed by adopting the above-described configuration, and the work can be performed quickly. Therefore, it is possible to automatically cancel the effects of sudden fluctuations and aging of the ambient temperature, contamination of the sample container, deterioration of the lamp as a light source, etc., and maintain measurement accuracy even when fully automatic operation is performed. An analyzer was obtained.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A spectroscopic analyzer using cereals as a sample S, which is one embodiment of the spectroscopic analyzer according to the present invention, will be described below.

As shown in FIG. 1, the spectroscopic analyzer irradiates a light source 1, a first optical system 2 for shaping a measuring light beam from the light source 1, and a measuring light beam from the first optical system 2. Sample holder 3 to be measured, a second optical system 4 for condensing the measurement light beam transmitted through the sample S held by the sample holder 3, and a measurement optical beam condensed by the second optical system 4 A spectroscopic analysis unit 5, which is an example of a light receiving container that spectrally analyzes a light beam, is arranged along the optical axis P.

The light source 1 comprises a tungsten-halogen lamp. The first optical system 2 comprises a lens 2a for shaping a light beam heading for the sample holder 3 into a parallel light beam. On the optical axis P of the bundle, between the light source 1 and the spectral analysis unit 5 (in the embodiment, on the side of the spectral analysis unit 5 of the sample holding unit 3), there is provided switching means 200 for switching this light beam to a predetermined state. I have. The switching means 200 includes a rotating disk 20 that rotates around an axis. As shown in FIG. 2, the rotating disk 20 includes a calibration filter that transmits a measurement light beam and converts it into a calibration light beam. Wavelength calibrating unit 20a, a reference unit 20b that transmits the measuring light beam and serves as a reference light beam, a dark current measuring shielding unit 20c that blocks the measuring light beam, and a notch that allows the measuring light beam to pass through as it is. A portion 20d is provided in the circumferential direction. Then, the state of the transmitted light is switched to each state by rotating the rotating disk 20 around the rotation axis 21. Here, by controlling the number of rotations of the rotating disk 20, the time interval at which the measuring light beam passes through each part can be set arbitrarily. Now, as shown in FIG. 3, the above-mentioned calibration light beam is a light beam having at least a pair of specific wavelength band (λ ₁ λ ₂ ) peaks, and a pair of peak wavelengths specified in advance and these peak wavelengths. From the positional relationship of the corresponding element positions of the array-type light-receiving element 7 that receives light, it is possible to establish correspondence between each element constituting the array-type light-receiving element and the wavelength of light received by each element. .

The sample holding section 3 is constituted by a quartz glass container 3a, in which grains as a sample S are stored. As shown in the figure, the container 3a has a retracting means 30a for a measuring section 30 through which the optical axis P of the measuring light beam passes, in a state crossing the optical axis P and a state separating from the optical axis P. It is configured to be able to move in and out freely. The second optical system 4 includes a condenser lens 4a for condensing the light beam transmitted through the sample S at the position of the entrance hole 5a of the spectral analyzer 5, and a dark box 4b for preventing harmful light from entering the optical path. It consists of.

The spectroscopic analysis unit 5 has an aluminum dark box 5b adjacent to the second optical system 4, and the dark box 5b
Within b, there is provided a concave diffraction grating 6 as spectral means for spectrally reflecting an incident light beam, and an array-type light receiving element 7 for detecting the intensity of the light beam for each wavelength that has been spectrally reflected. Further, between the entrance hole 5a and the concave diffraction grating 6 in the measurement optical path in the dark box 5b, a reflecting mirror 8 for reflecting the incident light beam from the entrance hole 5a toward the concave diffraction grating 6 is provided. It is provided. That is, the spectroscopic analysis unit 5 is a polychromator type spectrometer.

The array type light receiving element 7 is fixedly installed on a light receiving element fixing portion 9 provided in the dark box 5b on the optical path for dispersing the light beam by the concave diffraction grating 6, and is formed of silicon (S
i) or a lead sulfide (PbS) or germanium (Ge) sensor. The detection signal from the array type light receiving element 7 is sent to the processing means 70 and processed by the processing means 70 to obtain spectrum-related information such as the processed spectrum and the second derivative of the spectrum. Further, the link between the switching means 200 and the processing means 70 is adopted by the control means 10. Each component value can be calculated from the spectrum-related information according to the calibration formula stored in the processing means 70.
Now, the apparatus of the present application is provided with the processing means 70, the peak position detecting means 71 and the wavelength calibration confirming means 72 for confirming the wavelength calibration and the stabilization state of the optical system which are the characteristic constitutions of the present invention. Have been. First, the operation of the peak position detecting means 71 will be described with reference to FIG. In the figure, the horizontal axis indicates the element arrangement state of the above-mentioned array type light receiving element (the element number increases as the distance from the vertical axis increases), and the vertical axis indicates the amount of light received by each element. The illustrated wavelength range is in the vicinity of an element that receives a wavelength near the wavelength at which a wavelength peak is expected to be formed in the transmitted light of the calibration filter in advance, and corresponds to a specific center wavelength element (shown by a1 in the figure) By interpolating a total of seven light quantity data of three points before and after, respectively, the wavelength peak position (the distance set by the element number at the position corresponding to the element number in the array type light receiving element) as shown by A in FIG. 1/10 of
(Determining the wavelength peak position in 0 units) is required. In the figure, solid lines, broken lines, and dashed lines indicate changes in peak positions over time. Now, the peak position data thus captured is stored for each measurement and compared with the previous peak position data. A wavelength calibration confirming means 72 is provided for determining that the wavelength calibration of the optical system has been completed when the amount of change in the peak position data falls within a certain value. These means are, specifically, processing configurations on software. Actually, the wavelength calibration is completed by confirming the movement of the peak positions and by associating the wavelengths of at least one pair of wavelength peak positions with the element numbers as shown in FIG. Confirmation of school accuracy accompanying the above is completed by the former confirmation.

The operation sequence of the spectroscopic analyzer of the present invention will be described below in a bulleted form according to FIG. The data processing is performed by the processing means 70 linked with the switching means 200 described above. 1 Measurement Start (Wavelength Configuration Data Collection Process—First Stage) This state is the state shown in FIG. 5A, in which the container 3a is held in a retired state with respect to the measurement unit 30. There is nothing in 30. On the other hand, the rotating disk 20 assumes a state in which the wavelength calibrating unit 20a, which is the origin state, is positioned on the optical axis P. When the measurement light beam is irradiated, the light beam transmitted through the wavelength calibrator 20a is converted into a calibration light beam having a peak at a pair of specific wavelengths (λ ₁ λ ₂ ). The light is received by the mold light-receiving element 7, and the correspondence between each element and the wavelength becomes possible. This is performed for each sample measurement. At this time, the above-described peak position detecting means 71 and the wavelength calibration confirming means 72 operate to confirm the stability of the optical system and to confirm the wavelength received by each element provided in the array type light receiving element. FIG. 6 shows how the peak wavelength position changes after the power is turned on in this working state. FIGS. 6 (a) and 6 (b) show the peak positions of different wavelengths, respectively, and the wavelength peak position is calculated over time (in the illustrated example at intervals of 5 minutes) by the peak position detecting means 71. Calibration confirmation means 7
According to 2, it is determined that a stable state of the optical system is obtained after 25 minutes when the change in the light receiving position of the calibration at the wavelength of 740.0 nm becomes 0.03 or less, for example. Thus, the data collection of the wavelength calibration is completed. 2. Reference Data Collection Step (Second Step) This state is the state shown in FIG. 5 (b), and the container 3a is held in a retired state with respect to the measurement unit 30 as in the above-described step. There is nothing in the measurement unit 30. on the other hand,
The rotating disk 20 is rotated so that the reference portion 20b has the optical axis P.
Take the state located above. When the measurement light beam is irradiated, the light beam transmitted through the reference portion 20b is transmitted as a reference light by passing through a reference (eg, ground glass) in a measurement state (temperature), and the reference information Rd is obtained. can get. 3. Dark Information Collection Process (Third Step) This state is the state shown in FIG. 5C, in which the rotating disk 20 is rotated and the dark current measuring shield 20c is positioned on the optical axis. Therefore, in this state, no light enters the array type light receiving element 7 and dark information D in the measurement state is obtained. On the other hand, the container 3a in which the sample is filled into the container 3a is moved to the measuring unit 30. 4. Wavelength Calibration Process After completing the above process, wavelength calibration (processing on software) is performed in the processing means 70. That is, the wavelength of the light received by the element having the arbitrary element number p is derived from the relationship between the pair of peak wavelengths (λ ₁ , λ ₂ ) and the number of the pair of elements receiving the light, for example, by a linear relational expression. I do. 5 Sample Data Collection Process (Fourth Step) This state is the state shown in FIG. 5D, in which the container 3a is located in the measurement unit 30, and the measurement light beam is transmitted through the sample. Become. On the other hand, the rotating disk 20 is rotated so that the notch 20d is positioned on the optical axis P. Therefore, the sample information Sd is irradiated by the measurement light beam and receiving the transmitted light transmitted through the sample.
Can be obtained. 6 Process of Calculating Absorbance and Other Spectral Data From the sample information Sd, reference information Rd, and dark information D obtained in the above process, an absorbance d as information of a spectrum state is obtained according to the following equation. Absorbance d = log ((Rd-D) / (Sd-D)) Further, spectrum-related information such as the above-mentioned absorbance spectrum and the second derivative in the wavelength region of the spectrum is obtained and output. Furthermore, the component values of each component (moisture, protein, etc.) in the sample are determined using the second derivative of the spectrum at a plurality of specific wavelengths. In this calculation, in the spectral analyzer of the present application, wavelength calibration,
Since the reference measurement and the dark output measurement are performed for each measurement, the component amount can be specified accurately. Therefore, the reliability of the measurement is improved.

Alternative Embodiment (a) In the above embodiment, a tungsten-halogen bulb is used as the light source 1; however, the present invention is not limited to this, and can be set appropriately according to the sample S and the purpose of measurement. Yes, a heat radiator (black body furnace) as a light source 1 having continuous spectrum radiation in the entire infrared region, a light source 1 such as a mercury lamp, a Ne discharge tube, a laser emitting monochromatic light for measuring Raman scattering, etc. Can be used, and the configuration can be changed as appropriate. (B) Further, in the above embodiment, the sample S
Although the analysis was performed using the measurement light beam transmitted through the light source, this may be used as reflected light.

(C) In the above embodiment, the switching means is provided with a rotating disk, and each step is performed by rotating the rotating disk. However, as shown in FIG. Reference numeral 22 designates each part (wavelength calibration part 20a, reference part 20b, dark current measurement shielding part 20c, notch part 2
0d), and the state of the measurement light beam may be determined by moving the member 22 with respect to the optical axis P. (D) Further, in the above embodiment, the sample container is moved to the measuring unit in the third stage, but it is only necessary that the state in which the sample S is in the measuring unit 30 can be realized in the fourth stage. . The means for performing this is called leaving means. (E) In the above-described embodiment, an example in which the component analysis value (component content) is obtained from the second derivative spectrum of the absorbance has been described. However, when the sample is rice, the taste value may be obtained. It is possible.

In the claims, reference numerals are provided for convenience of comparison with the drawings, but the present invention is not limited to the configuration shown in the attached drawings.

[Brief description of the drawings]

FIG. 1 is a diagram showing a configuration of a spectroscopic analyzer.

FIG. 2 is a diagram showing a configuration of a rotating disk.

FIG. 3 is a diagram showing a state of a calibration light beam;

FIG. 4 is an explanatory diagram of a state of a change in a peak position in a calibration light beam;

FIG. 5 is a diagram showing a positional relationship among a light source, a sample container, a rotating disk, and a spectroscopic analyzer in each measurement state.

FIG. 6 is a diagram showing a change state of a peak position over time.

FIG. 7 is a diagram showing another configuration example of the switching means.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Light source 6 Spectroscopic means 7 Array type light receiving element 10 Control means 20a Wavelength calibration unit 20b Reference unit 20c Dark current measurement shielding unit 20d Notch unit 30 Measurement unit 71 Peak position detection unit 72 Wavelength calibration confirmation unit 200 Switching unit

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-6-74823 (JP, A) JP-A-55-161346 (JP, A) JP-A-6-50889 (JP, A) JP-A-6-48889 74825 (JP, A) Special Table Hei 5-509413 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) G01N 21/00-21/01 G01N 21/17-21/61 G01J 3/00-3/52 JICST file (JOIS)

Claims (1)

(57) [Claims] A light source (1) for irradiating a measurement light beam to a measurement unit (30) from which a sample (S) to be measured can come and go.
Through the measuring unit (30) or the measuring unit (3
0) a spectroscopic means (6) for dispersing the measuring light beam reflected from the light source, and an array type light receiving element (7) for receiving the separated measuring light beam; A wavelength calibration unit (2) including a calibration filter between the light source (1) and the spectroscopic means (6) on the road, which transmits the measurement light beam to form a calibration light beam having a pair of wavelength peaks.
0a) for performing spectral analysis after performing wavelength calibration, wherein a position change of the wavelength peak (A) in the calibration light beam on the array-type light receiving element (7) is determined with time. And a wavelength calibration confirming means (72) for determining that the wavelength calibration has been completed when the positional change with time becomes equal to or less than a predetermined value.