JPH10115583A - Spectrochemical analyzer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To downsize a structure of a spectrochemical analyzer by using a light emitting diode as a light source for the analyzer. SOLUTION: A light source LS comprises a light emitting diode 11 with an active layer comprising GaAs, providing a light emission wavelength with a center wavelength of approximately 890nm and a full width at half maximum of approximately 40nm. An irradiation part 13 comprises a holding part 13a and a bowl-shaped rubber pad 13b in tight contact with a sample S for shielding external light, while a light reception part 14 comprises a holding part 14a also holding an optic fiber 16 and a bowl-shaped rubber pad 14b. A spectrometer 20 reflects light which has transmitted through the sample S and is incident from an incident hole 20a while being led by the optic fiber 16 on a reflection mirror 17, spectrally reflects it by a concave diffraction grating 18, and detects light intensity by an arrayed light reception element 19. An arrayed direction of the light reception elements 19 is made to align with a spectral direction of the concave diffraction grating 18, thereby directly obtaining a spectral spectrum. The light emitting diode 11 is compact, whose constitution allows the spectrochemical analyzer to be downsized.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an irradiating section for irradiating a sample with a measuring light beam from a light source, a light receiving section for receiving light transmitted through or reflected by the sample, and a light receiving section for receiving the light. The present invention relates to a spectroscopic analyzer provided with a spectroscopic analyzer for obtaining a light spectrum and obtaining components contained in the sample based on the obtained spectrum.

[0002]

2. Description of the Related Art In such a spectroscopic analyzer, a light beam for measurement is radiated from an irradiating section toward a sample such as fruits and vegetables, and transmitted light or reflected light of the sample is received by a light receiving section. It is known that transmitted light or reflected light of a sample has a spectral spectrum corresponding to the component contained in the sample, for example, light of a specific wavelength is absorbed by the component contained in the sample. Thus, the spectral analysis means obtains the spectrum of the transmitted light or the reflected light of the sample, and the components contained in the sample can be obtained based on the obtained spectrum. By the way, as a light source for the spectroscopic analysis, a halogen lamp has conventionally been generally used.

[0003]

However, in the above-mentioned conventional configuration, since the halogen lamp generates strong heat,
A configuration for preventing the heat from being transmitted to the sample is required, and the size of the halogen lamp itself is large, so that there is an inconvenience that the apparatus becomes large. The present invention has been made in view of the above circumstances, and has as its object to reduce the size of an apparatus as much as possible.

[0004]

According to the first aspect of the present invention, the light from the light emitting diode is emitted toward the sample from the irradiation unit, and the light transmitted through the sample or reflected by the sample is emitted. Is received by the light receiving section, and the components contained in the sample are obtained from the spectrum by the spectral analysis means. Since the emission spectrum of the light emitting diode has a certain extent, the light emitting diode can be used as a light source for spectroscopic analysis. However, this light emitting diode is a very small semiconductor element and does not generate enough heat to cause a problem. Therefore, it is not always necessary to provide a configuration for preventing heat from being transmitted to the sample. Therefore, by employing a light emitting diode as a light source, the device configuration of the spectroscopic analyzer can be made as small as possible.

[0005] In addition, by providing the structure according to the second aspect, light from a plurality of light emitting diodes having different emission wavelengths is irradiated toward the sample from the irradiation unit, and is included in the sample by the spectral analysis means. Required components. Since the emission spectrum of the light emitting diode has a certain extent, it can be used alone as the light source of the spectroscopic analyzer.However, depending on the type of component of the sample to be obtained or the specific accuracy of the component, etc. The width of the spectrum may not be sufficient. In such a case, by using a plurality of light emitting diodes having different emission wavelengths as light sources as described above, various measurements can be made, and the spectroscopic analyzer can be made more convenient.

[0006] With the configuration of the third aspect, the spectroscopic analysis means obtains a second derivative of the spectral spectrum and obtains a component contained in the sample based on the second differential value. Therefore, even if the change of the signal with respect to the wavelength in the spectral spectrum is small, the feature of the spectral spectrum can be effectively extracted, so that the accuracy of obtaining the component can be improved.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an embodiment in which the present invention is applied to a case where a component contained in a fruit or vegetable which is a sample S to be measured is determined will be described with reference to the drawings. As shown in FIG. 1, the spectroscopic analyzer 1 includes a light source LS, a condenser lens 12 for condensing a measurement light beam from the light source LS, and an irradiating unit that irradiates the sample S with the condensed measurement light beam. 13, a light receiving unit 14 for receiving the transmitted light from the sample S, and a sample supporting unit 1 for supporting the sample S located between the irradiation unit 13 and the light receiving unit 14.
5 and an optical fiber 1 for guiding the transmitted light received by the light receiving section 14
6, a spectroscope 20 for obtaining a spectrum of transmitted light guided by the optical fiber 16, and an analyzer 21 for analyzing a spectrum detected by the spectrometer 20 to obtain a component contained in the sample S. Have.

The light source LS comprises a light emitting diode 11 whose active layer is made of GaAs.
Has an emission wavelength with a center wavelength of about 890 nm and a full width at half maximum of about 40 nm, as shown in the emission spectrum of FIG. The irradiation unit 13 includes a holding unit 13a and a bowl-shaped rubber pad 13b that is in close contact with the sample S and blocks light from the outside. Similarly, the light receiving section 14 is also composed of a holding section 14a for holding the optical fiber 16 and a bowl-shaped rubber pad 14b.

The spectroscope 20 includes a reflecting mirror 17 that reflects light guided by the optical fiber 16 and incident from the entrance hole 20a;
A concave diffraction grating 18 for spectrally reflecting the transmitted light of the sample S reflected by the reflecting mirror 17 and an array-type light receiving element 19 for detecting the intensity of light spectrally reflected by the concave diffraction grating 18 are provided. The array type light receiving element 19 is configured by arranging a large number of light receiving elements one-dimensionally, and is arranged such that the arrangement direction coincides with the spectral direction of the concave diffraction grating 18 (the vertical direction in FIG. 1). , Array type light receiving element 1
A spectral spectrum can be obtained directly from the signal outputs of FIG.

The analyzer 21 is constructed using a microcomputer, processes an output signal from the array type light receiving element 19, and obtains an absorbance spectrum and a second derivative of the absorbance spectrum. The components contained in the sample S are obtained by calculating the amounts thereof (hereinafter, referred to as “component amounts”) based on the second derivative. The absorbance is defined as Log (I / T), where I is the irradiation light amount (reference light amount) of the light source LS and T is the light amount of the transmitted light.

The amount of components contained in the sample S is expressed by the following equation (1)
(Hereinafter referred to as "component amount calculation formula")
It is calculated based on: Y = K₀+ K₁A (λ₁) + K_TwoA (λ_Two) + K_ThreeA (λ_Three) + ... (1) where Y is the component amount, K₀, K₁, K_Two, K_Three......
Number, A (λ₁), A (λ _Two), A (λ_Three) ... is the wavelength λ
₁, Λ_Two, Λ_ThreeSecondary fineness of the absorbance spectrum at ……
Minute value.

The above K ₀ , K ₁ , K ₂ , K ₃ ... And the wavelengths λ ₁ , λ ₂ , λ ₃ ... Are determined experimentally, and previously determined values are stored. . Above wavelength λ
₁ , λ ₂ , λ ₃ ... When the component to be determined is glucose, for example, 750 nm, 8
30 nm, 915 nm, 1030 nm, 1080 nm,
1205 nm, 1260 nm and 1380 nm, and in the case of citric acid, for example, 775 nm, 900 n
m, 1005 nm, 1060 nm, 1170 nm, 12
40 nm and 1375 nm, and in the case of ascorbic acid, for example, 760 nm, 920 nm, 99 nm
5 nm, 1200 nm, 1265 nm and 1355 nm
And so on.

In this embodiment, among the above wavelengths, 830 nm and 915 nm for glucose, 900 nm for citric acid, and 92 nm for ascorbic acid
Detection at 0 nm is possible. From the viewpoint of component amount detection accuracy, as much as possible, the more the wavelength to be detected is better,
As described above, the components of the sample S can be easily obtained even with one or two wavelengths. Therefore, the spectroscope 20 and the analyzer 21 constitute a spectral analysis unit SA that obtains a spectral spectrum of light received by the light receiving unit 14 and obtains a component contained in the sample S based on the obtained spectral spectrum. .

[Other Embodiments] Other embodiments will be listed below. In the above embodiment, the light source LS is constituted by a single light emitting diode 11, but as shown in FIG. 3, a plurality (specifically, three) of light emitting diodes 30a and 30b having different emission wavelengths are provided. , 30c may be arranged side by side. These three light emitting diodes 30a, 30b,
30 each have an emission spectrum shown in FIG.
The shortest light emitting diode 30a having a center wavelength of 820 nm
The active layer is formed of AlGaAs, and the middle 890n
m of the light emitting diode 30b is formed of GaAs, and the longest light emitting diode 30c of 1000 nm is made of InGa.
It is formed of AsP. As a result, the wavelength selection range for determining the component amount in the above equation (1) is widened, and the components can be obtained more accurately. FIG.
Although the three light emitting diodes 30a, 30b, and 30c are illustrated as being housed in independent packages, the three light emitting diodes may be housed in one package. Further, the number of light emitting diodes having different emission wavelengths may be further increased.

In the above embodiment, the configuration is such that the transmitted light of the sample S is guided to the spectroscope 20, but the projection light of the light emitting diode 11 is incident on the spectroscope, and the light having a narrow wavelength width and a variable wavelength is emitted. A configuration may be adopted in which a spectrum is obtained by generating, irradiating the sample S with the light, and detecting transmitted light. In the above embodiment, the configuration is such that the spectral spectrum of the transmitted light of the sample S is obtained and spectral analysis is performed. However, the spectral analysis of the reflected light of the measuring light beam irradiated on the sample S may be performed.

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

[Brief description of the drawings]

FIG. 1 is a block diagram of a spectroscopic analyzer according to an embodiment of the present invention.

FIG. 2 is a diagram showing an emission spectrum of the light source according to the embodiment of the present invention.

FIG. 3 is a block diagram of a spectroscopic analyzer according to another embodiment of the present invention.

FIG. 4 is a diagram showing an emission spectrum of a light source according to another embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 11 Light emitting diode 13 Irradiation part 14 Light receiving part 30a, 30b, 30c Plural light emitting diodes LS Light source SA Spectroscopic analysis means

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Seishi Igawa 1-1-1 Hama, Amagasaki-shi, Hyogo Pref.

Claims (3)

[Claims] An irradiation unit (13) for irradiating a sample with a measuring light beam from a light source (LS), a light receiving unit (14) for receiving light transmitted through or reflected by the sample, and a light receiving unit thereof (14) a spectral analysis apparatus provided with a spectral analysis means (SA) for obtaining a spectral spectrum of the received light and obtaining a component contained in the sample based on the obtained spectral spectrum; (LS) The spectroscopic analyzer which is comprised of the light emitting diode (11). 2. The light source (LS) comprises a plurality of light emitting diodes (30a), (30b), (3) having different emission wavelengths.
The spectroscopic analyzer according to claim 1, wherein the spectroscopic analyzer is constituted by 0c). 3. The spectroscopic analysis means (SA) is configured to determine a second derivative of the spectrum, and to determine a component contained in the sample based on the second derivative. 3. The spectroscopic analyzer according to 1 or 2.