JPH03221843A - Analyzer by light - Google Patents

Abstract

PURPOSE:To simplify a signal processing system by forming a filter for reference as a wide band-pass filter which allows the selective transmission of light in a continuous range from a short wavelength to a long wavelength. CONSTITUTION:The analyzer 10 is constituted of an IR radiation light source 12, A filter set 14 mounted with a filter 14A for measurement and the filter 14B for reference, a sample cell 16, a detector 18, an output signal amplifier 20 thereof and the signal processing system 22 therefrom. The filter 14B for reference is formed as the wide band-pass filter which allows the selective transmission of the light in the continuous range from the light of the wavelength shorter than the wavelength of measuring light to the light of the wavelength longer than the same and, therefore, even if the spectral sensitivity is fluctuated by the temp. fall of the detector 18, there is no measurement error by this fluctuation and the exact analysis is executed.

Description

[Detailed description of the invention]

[Industrial Application Field 1] This invention analyzes the component concentration of an object to be measured, such as a gas, by utilizing the absorption of the measurement light, or the absorption of the measurement light on the surface of a tobacco leaf. This invention relates to an optical analyzer for analyzing the moisture content of tobacco leaves. [Prior art 1] Conventionally, in this type of light analyzer, for example, a gas analyzer, light from a light radiation source is passed through a measurement filter as measurement light of a specific wavelength through a gas to be measured. Utilizing the absorption of measurement light, the concentration of components in gases, such as C○, C, CO2 in automobile exhaust gas, C○, Se2, N 02 in combustion exhaust gas, zero in fuel leakage gas, etc. It is used for analysis of 4.03H8. Here, the light transmitted through the gas to be measured is, for example, PbS
It is adapted to be detected by a detector consisting of an e-cell. Since the above-mentioned optical radiation source or detector is prone to drift, the measurement light, which is absorption wavelength light, is transmitted through the gas to be measured using light with a wavelength that is less absorbed as reference light. The concentration of the target component is determined from the ratio of the amount of light received by the detector to the signal amount of the reference light and measurement light. Incidentally, the spectral sensitivity of the PBSE cell constituting the detector, indicated by the solid line A in FIG. 4, changes significantly as indicated by the broken line B as the element temperature decreases. Therefore, if only one type of reference light is used, measurement errors will increase. In contrast, conventionally, as shown in FIG. 4, two types of reference light beams E and F, which are close to the measurement wavelength and have wavelengths on both sides thereof, are used.

[Problem to be solved by the invention]

However, as described above, when two types of reference light beams are used, two reference filters and one measurement filter are required, resulting in high costs and inconvenience in handling. Furthermore, since three types of signals must be compared, there is also the problem that the signal processing system becomes complicated. The present invention has been made in view of the above-mentioned conventional problems, and an object of the present invention is to provide an optical analyzer that uses two filters and has simple signal processing.

[Means to solve problems] The present invention includes a light radiation source, a measurement filter that selects light of a specific wavelength as measurement light from the light of the light radiation source, and a measurement filter that selects a specific wavelength light from the light of the light radiation source that is close to the wavelength of the measurement light and has the same wavelength. a reference filter that selects a short-wavelength reference light with a shorter wavelength and a long-wavelength reference light with a longer wavelength; In a light analyzer that analyzes the components of the object to be measured based on the ratio of the measurement light and reference light in transmitted light or reflected light, the reference filter is connected to a continuous light source from the short wavelength reference light to the long wavelength reference light. The above object is achieved by providing a wide bandpass filter that selectively transmits light in a targeted range. [Effect]

In this invention, the reference filter is a wide bandpass filter that selectively transmits light in a continuous range from shorter wavelength light to longer wavelength light with the wavelength of measurement light in between, so for example, Even if the spectral sensitivity of a detector made of a PbSe cell fluctuates due to a decrease in temperature, there is no measurement error due to the fluctuation, and accurate analysis can be performed.

【Example】

Embodiments of the present invention will be described below with reference to the drawings. In this embodiment, the present invention is applied to a gas analyzer, and this gas analyzer 10 includes a light radiation source 12 that emits infrared light, a filter set 14, a sample cell 16, and a Pb
It is composed of a detector 18 made of a Se cell, an amplifier 20 that amplifies the output signal of the detector 18, and a signal processing system 22 that processes the signal from the amplifier 20. The filter set 14 includes a measurement filter 14A.
and a reference filter 14B are attached. The measurement filter 14A is configured to select, from the light radiation source 12, light having a wavelength that is absorbed by the target component to be measured in the gas to be measured contained in the sample cell 16. For example, if the target component is mouth 20, 1.4.1.9,
Or 2.7μm, 3,4μIII for mouth C, CO
In the case of 2, a filter is selected that selects light with a wavelength of 4.3 μm, and in the case of 1C○, a wavelength of 4.7 μm. Further, the reference filter 14B is a wide bandpass filter that continuously transmits wavelength light within a constant width range centered around the wavelength of the measurement light selected by the measurement filter 14A. For example, if the component to be measured is CO2 and the wavelength selected by the measurement filter 14A is 4°3 μm, as shown in FIG.
Waveform 1 showing the relationship between wavelength and transmittance of selected light according to 4A
When the full width at half maximum of 4a is 60 nm, in the wavelength range of about 20 @ of 60 nl'Il centered on 4.3 μm,
The light has been chosen. As a specific example of the reference filter 14B in this case,
For example, there is one with a wavelength of 3.3 to 4.5P and an average transmittance of 5%. As mentioned above, if the transmission wavelength range of the reference filter 14B is widened before and after the transmission wavelength of the measurement filter 14A, the influence of gases contained in the air such as the gas to be measured, moisture, and carbon dioxide can be reduced. Since it can be made small and the same effect as using other types of reference filters can be obtained, measurement accuracy can be improved in response to changes in spectral sensitivity characteristics due to changes in detector temperature. In the above embodiment, the substance to be measured is a gas, and the measurement light and the reference light are transmitted through the gas, but the present invention is not limited to this, and the measurement light and the reference light are transmitted through the gas. It can also be applied to cases in which an object to be measured is irradiated with light and components of the object to be measured are analyzed from the reflected light. For example, the third
As shown in the figure, there is a moisture meter 28 that irradiates the tobacco confectionery 24 and measures the absorption rate on the surface of the tobacco leaf 24 from the reflected light to analyze the moisture content of the tobacco leaf 24. This also applies to cases where: Reference numerals 26A and 26B in FIG. 3 indicate mirrors.

【Effect of the invention】

Since the present invention is constructed as described above, the number of reference filters can be reduced to one, thereby reducing product costs, simplifying handling, and simplifying the signal processing system. It has the excellent effect of being able to

[Brief explanation of drawings]

Figure 1 is a block diagram showing an embodiment in which the present invention is applied to a gas analyzer, and Figure 2 is a line showing the relationship between the transmittance of the measurement and reference filters and the spectral sensitivity of the detector in the same embodiment. Figure 3 is an optical system diagram showing an example in which the present invention is applied to a moisture analyzer, and Figure 4 shows the transmittance of the measurement filter and reference filter and the spectral sensitivity of the detector in a conventional gas analyzer. FIG. DESCRIPTION OF SYMBOLS 10... Gas analyzer, 12... Light radiation source, 14... Filter set, 14A... Measurement filter 14B... Reference filter 16... Sample cell, 18... Detector , 24... Tobacco leaf, 28... Moisture meter.

Claims (1)

[Claims] (1) a light radiation source; a measurement filter that selects light of a specific wavelength as measurement light from the light of the light radiation source; a reference filter that selects a short wavelength reference light with a short wavelength and a long wavelength reference light with a long wavelength; In a light-based analyzer that analyzes the components of the object to be measured from the ratio of the measurement light and reference light in the light or reflected light, the reference filter is continuously connected to the light from the short wavelength reference light to the long wavelength reference light. An optical analyzer characterized by a wide bandpass filter that selectively transmits a range of light.