JPH10160666A - Spectral analyzer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve measurement work efficiency while suppressing configuration of spectral analyzer from being more complex to the best. SOLUTION: The device comprises an irradiation part 13 which irradiates a measurement light ray from a light source part LS to a sample, a photo- detecting part 14 which photo-detects the light transmitting or reflected on the sample, and a spectral analysis means which, based on the light detected with the light photo-detecting part 14, obtains component contained in the sample. The light source part LS comprises a semiconductor laser element 2 and a laser driving means which modulates an injection current to the semiconductor laser element 2 with a repeated signal of set cycle, and the spectral analysis means extracts, among the light photo-detected with the photo-detecting part 14, the signal component which changes in synchronous with the repetition signal of the set cycle, and based on the extracted signal component, obtains a component contained in the sample.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an irradiating section for irradiating a sample with a measuring light beam from a light source section, a light receiving section for receiving light transmitted through or reflected by the sample, and a light receiving section for receiving the light. And a spectroscopic analysis unit for obtaining a component contained in the sample on the basis of the obtained light.

[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. Depending on the components contained in the sample, it absorbs light of a specific wavelength, etc., so even if the intensity of the measurement light beam applied to the sample is constant, the reflected light or The intensity of the transmitted light changes. Therefore,
The components contained in the sample can be obtained by measuring the intensity of the transmitted light of the sample at a specific wavelength or the intensity of the reflected light from the sample by the spectroscopic analysis means. By the way, since the intensity of the transmitted light of the sample or the reflected light from the sample is not so strong, conventionally, the sample, the irradiation unit, the light receiving unit, and the like are measured in a dark box or measured in a dark room. The measurement was performed in a state where disturbance light was blocked.

[0003]

Therefore, in the above-described conventional configuration, it takes much time and effort to measure the disturbance light to block the disturbance light. Further, in order to avoid such inconvenience, the light from the light source unit is intermittently turned on by a so-called chopper into a pulse light having a constant cycle, and the sample is irradiated from the irradiation unit to the light received from the light receiving unit. A technique has been considered to suppress the influence of disturbance light by extracting components that change in synchronization with the pulsed light.However, a chopper equipped with a rotary drive mechanism is required, and the device configuration of the spectrometer is required. However, there is a disadvantage that the size becomes large. The present invention has been made in view of the above circumstances, and an object of the present invention is to improve measurement work efficiency while minimizing the complexity of the configuration as much as possible.

[0004]

According to the first aspect of the present invention, a light source unit for irradiating a measuring light beam is provided.
The injection current to the semiconductor laser element is modulated by a repetition signal of a set period, and a measurement light beam whose light intensity changes according to the modulation state is emitted. The measurement light beam from the light source unit is applied to the sample to be measured from the irradiation unit, and the light reflected by the sample or the light transmitted through the sample is received by the light receiving unit.
Then, the spectral analysis means extracts, from the light received by the light receiving unit, a signal component that changes in synchronization with a repetition signal of a set period that modulates the injection current of the semiconductor laser element, and based on the extracted signal component. To determine the components contained in the sample.

That is, the semiconductor laser element has a unique property that the intensity of the emitted light changes when the injection current to the semiconductor laser element is changed. Therefore, by utilizing the property, the intensity of the light irradiating the sample is adjusted at a set period. Can be changed repeatedly. Then, by extracting a signal component that changes in synchronization with a change in the intensity of the emitted light from the semiconductor laser element from the transmitted light of the sample or the reflected light from the sample, the case where disturbance light is incident on the light receiving unit is obtained. However, it is possible to suppress the influence of disturbance light that does not change in synchronization with the change in the intensity of the light emitted from the semiconductor laser element, and it is not necessary to perform light shielding on the sample so strictly. Thus, the measurement operation efficiency can be improved with a simple configuration that only modulates the injection current of the semiconductor laser element by utilizing the intrinsic properties of the semiconductor laser element.

In addition, with the configuration of the second aspect, the light source section is provided with a plurality of semiconductor laser elements having different emission wavelengths, so that spectral analysis can be performed at a plurality of wavelengths. In other words, it is possible to perform spectral analysis with only a single wavelength, but by performing spectral analysis with multiple wavelengths as described above, it is possible to cope with the case where it is desired to obtain multiple components contained in a sample. In addition, the spectroscopic analyzer can be made more convenient.

[0007] With the configuration according to the third aspect, when spectroscopic analysis of the sample is performed, the sample is mounted on the sample mounting unit provided near the irradiation unit and the light receiving unit and measured. . At the time of this spectroscopic analysis, the spectroscopic analysis means performs the spectroscopic analysis in a state where the sample mounting section maintains the posture at the time of the sample mounting operation and the sample is irradiated with external light. In other words, it is possible to proceed to the measurement operation simply by setting the sample to be measured on the sample mounting portion. Compared to a configuration that opens and closes each time, the operation of exchanging the sample can be extremely simplified, and the efficiency of the measurement operation can be improved as much as possible. Then, even when the sample is irradiated with external light and acts as disturbance light, the influence can be suppressed as described above.

[0008] With the above configuration, the laser driving means modulates the injection current of the semiconductor laser element with a sine wave signal or a pulse signal having a set period. That is, since a simple signal is used as the repetition signal of the set cycle, a signal component that changes in synchronization with the repetition signal of the set cycle is extracted from the laser driving unit itself and the light received by the light receiving unit. The configuration of the spectroscopic analysis means can be simplified.

[0009]

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 unit LS, an irradiation unit 13 that irradiates the sample S with a measurement light beam from the light source unit LS,
A light receiving unit 14 for receiving the transmitted light from the light source, a sample mounting unit 15 located between the irradiation unit 13 and the light receiving unit 14 at a position close to any of them, and a transmission light received by the light receiving unit 14. The light-receiving element 6 includes a light-receiving element 6 that detects light, and an analysis unit AN as a spectral analysis unit that obtains a component contained in the sample S based on the intensity of the light detected by the light-receiving element 6.

The irradiating section 13 is composed of a holding section 13a and a bowl-shaped rubber pad 13b which is in close contact with the sample S and shields external light. Similarly, the light receiving section 14 is also constituted by a holding section 14a and a bowl-shaped rubber pad 14b. A sample mounting table 15a having a sample mounting surface whose upper surface is convexly curved downward is attached to the sample mounting unit 15,
The sample S to be measured is easily mounted on the sample mounting section 15.

The light source section LS is provided with a semiconductor laser element 2 as a light source and a condensing lens 3 for condensing light emitted from the semiconductor laser element 2 fixed to a mount 4 and a spectroscopic analyzer. A laser drive circuit 5 that supplies a drive current to the semiconductor laser element 2 while being housed in the lower housing 1a is provided. The laser drive circuit 5 is shown in FIG.
As shown in (a), the injection current to the semiconductor laser element 2 is modulated by a sine wave signal which is a repetitive signal of a set period, and functions as a laser driving unit. The laser drive circuit 5 includes a sine wave oscillation circuit 5a for the modulation, and modulates the injection current at the oscillation frequency f0 of the sine wave oscillation circuit 5a. In accordance with the modulation of the injection current, the output light intensity of the semiconductor laser element 2 changes in a sine wave shape as shown in FIG.

The analysis section AN is provided in the lower housing 1a of the spectroscopic analyzer 1, and as shown in FIG. 2, mainly includes a band-pass filter circuit 7, a multiplication circuit 8, a low-pass filter circuit 9, and a microcomputer. It comprises an arithmetic unit 10 configured by utilizing. The bandpass filter circuit 7 selectively passes a signal having a frequency near the modulation frequency f0 of the semiconductor laser element 2 from the detection signal of the light receiving element 6,
The multiplication circuit 9 outputs the output of the band-pass filter circuit 7 and the frequency f of the sine wave oscillation circuit 5 a of the laser drive circuit 5.
Multiplied by a sine wave signal of 0, and a low-pass filter circuit 9
Allows the multiplication circuit 9 to pass only the signal of the low frequency component in the output. In other words, a circuit from the band-pass filter circuit 7 to the low-pass filter circuit 9 constitutes a so-called lock-in amplifier, and converts a detection signal of the light receiving element 6 into a repetition signal of a set period which is a modulation signal for the semiconductor laser element 2. It extracts signal components that change synchronously. Therefore, external light enters the light receiving unit 14 and
The measurement can be performed in a state where the influence of external light, that is, disturbance light, incident on the light receiving element 6 is reduced.

The arithmetic unit 10 includes a low-pass filter circuit 9
Calculates the transmittance of sample S from the input signal from
Find the components contained in The case where it is desired to determine whether or not glucose is contained in the sample S will be specifically described as an example. Glucose is 750 nm, 830 nm, 9
15nm, 1030nm, 1080nm, 1205n
Since the semiconductor laser device 2 has a characteristic absorption characteristic at wavelengths such as m, 1260 nm, and 1380 nm, for example, an InGaAsP-based semiconductor laser device having an emission wavelength of 1260 nm is employed, and the absorbance of the measurement light beam in the sample S is measured. Thus, it can be determined whether or not the sample S contains glucose. In addition to glucose, various components can be obtained by selecting and using emission wavelengths according to the absorption characteristics of various components.

In the actual measurement operation, the operator sequentially performs the operation of replacing the sample S on the sample mounting table 15a from the measured one to the unmeasured one and the operation of turning on and operating a switch (not shown) for instructing a measurement start. The measurement of a plurality of samples S is repeatedly performed continuously. At the time of the measurement work, the periphery of the sample mounting portion 15 is open, and the exchange of the measured sample S and the unmeasured sample S can be easily performed. In addition, as described above, even when external light is incident, the measurement can be performed while eliminating the influence of the external light. Therefore, the state in which the sample mounting unit 15 mounts the sample S to be measured on the sample mounting table 15a. While maintaining
That is, the measurement can be performed while the external light is being irradiated.

[Other Embodiments] Other embodiments will be listed below. In the above-described embodiment, the light source section LS is provided with a single semiconductor laser element 2, but may be provided with a plurality of semiconductor laser elements 2 having different emission wavelengths. By providing a plurality of semiconductor laser elements 2 having different emission wavelengths in this manner, for example, when detecting whether or not the sample S exemplified in the above embodiment contains glucose as a component, The emission wavelength of the laser element 2 is set to each of the characteristic wavelengths in the glucose absorption characteristic, a sample S whose glucose component amount is known is measured in advance, and the measurement result is stored, and the component amount is unknown. By comparing the measurement result of the sample S with the stored information, the presence or absence and the amount of glucose can be measured more accurately.

The emission wavelength of each semiconductor laser element 2 is
In addition to glucose, a plurality of components contained in the sample S may be obtained by setting an emission wavelength corresponding to the specific absorption of citric acid or ascorbic acid. In addition, as an aspect in which a plurality of semiconductor laser elements 2 are provided, a configuration in which chips of a plurality of semiconductor laser elements are arranged side by side in one package in a light emitting direction or a plurality of semiconductor laser elements 2 In addition, various configurations such as a configuration in which a driving unit for positioning on the optical axis for measurement is provided and the position of each semiconductor laser element 2 is sequentially switched for measurement are possible.

In the above-described embodiment, a sine wave signal is exemplified as a repetition signal of a set cycle for modulating an injection current to the semiconductor laser element 2. However, for example, the signal may be modulated by a pulse signal of a set cycle. . In this case, the light receiving element 6
Is sampled once per one cycle of the repetitive pulse signal, and the average value of an arbitrary point on the signal waveform is obtained, or the waveform itself is accurately recorded by sequentially shifting the sampling time. Utilizing the principle of the boxcar integrator, the transmitted light of the sample S can be detected in a state where the influence of disturbance light is reduced.

In the above-described embodiment, the case where the wavelength of the measuring light beam from the light source unit LS is fixedly set is exemplified.
It may be configured as an R laser, and the emission wavelength may be changed by changing the injection current to the DBR section. With such a configuration in which the emission wavelength changes, a spectral spectrum of the absorbance can be obtained, so that the component contained in the sample S can be obtained from the second derivative of the spectral spectrum, and the measurement accuracy is improved. be able to. still,
In this case, it is desirable that the change of the emission wavelength is sufficiently slower than the modulation frequency of the injection current of the semiconductor laser device 2.

In the above embodiment, the analysis unit AN includes the band-pass filter circuit 7 and the like, and extracts a signal component that changes in synchronization with a repetition signal of a set cycle for modulating the injection current of the semiconductor laser device 2. However, a configuration may be adopted in which the processing by all of these circuits is performed by the arithmetic device 10. In the above embodiment, the light receiving unit 14 is configured to receive the light transmitted through the sample S. However, the light receiving unit 14 may be configured to receive the light emitted from the irradiation unit 13 and reflected by the sample S. .

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 schematic configuration diagram of a spectroscopic analyzer according to an embodiment of the present invention.

FIG. 2 is a schematic block diagram of a spectroscopic analyzer according to an embodiment of the present invention.

FIG. 3 is an explanatory diagram of a modulation state of a measuring light beam according to the embodiment of the present invention.

[Explanation of symbols]

 2 Semiconductor laser element 5 Laser driving means 13 Irradiation part 14 Light receiving part 15 Sample mounting part AN Spectroscopic analysis means LS Light source part

 ──────────────────────────────────────────────────の Continuing from the front page (72) Inventor Hirokazu Ikeda 1-1-1 Hama, Amagasaki-shi, Hyogo Pref.

Claims (4)

[Claims] An irradiation unit (13) for irradiating a sample with a measurement light beam from a light source unit (LS), a light receiving unit (14) for receiving light transmitted through the sample or reflected by the sample, and receiving the light. A spectral analysis unit (AN) for obtaining a component contained in the sample based on light received by the unit (14), wherein the light source unit (LS) is a semiconductor laser device (2). ), And a laser driving means (5) for modulating an injection current to the semiconductor laser element (2) with a repetitive signal of a set period. The spectroscopic analysis means (AN) comprises: (14) is configured to extract, from the light received, a signal component that changes in synchronization with the repetition signal of the set period, and obtain a component included in the sample based on the extracted signal component. Spectrometer. 2. The spectroscopic analyzer according to claim 1, wherein the light source section (LS) is provided with a plurality of semiconductor laser elements (2) having different emission wavelengths. 3. The irradiating section (13) and the light receiving section (1).
A sample mounting part (15) for mounting a sample to be subjected to spectroscopic analysis is provided near 4), and the spectroscopic analysis means (AN) is provided with the sample mounting part (15).
3. The spectroscopic analyzer according to claim 1, wherein the apparatus is configured to calculate a component contained in the sample while maintaining a posture of the sample during the mounting operation and irradiating the sample with external light. 4. 4. The spectroscopic analyzer according to claim 1, wherein the repetition signal of the set cycle is a sine wave signal or a pulse signal of the set cycle.