JPH0359443A - Device for spectrochemical analysis - Google Patents

Abstract

PURPOSE:To improve working efficiency and to simplify a device by constituting a light receiving part of a spectroscope for dispersing optical paths and an optical sensor having resolving power in the optical path dispersion direction thereof in order of the wavelengths of light. CONSTITUTION:The light receiving part 5 is provided with a prism 7 as the spectroscope for dispersing the optical path and the optical sensor 9 having the resolving power in the optical path dispersion direction of the light transmitted through the prism 7 in order of the wavelengths of the light from a collimator 6. The light emitted from a light source 3 transmits an object F to be measured and a filter 4 and is made incident through the collimator 6, the prism 7 and a lens system 8 on the sensor 9. The filter 4 having the peak transmission wavelength lambdao at about 685 nm is selected in the case of identification of the chlorophyll having a correlative relation with the sugar content of an object (fruit) F to be measured. The photodetector S0 of the sensor 9 corresponding to the wavelength lambdao can be identified by detecting the detector having the max. light receiving intensity. The photodetectors S1, S2 in the positions apart by a prescribed distance forward/backward from the detector S0 are selected.

Description

Detailed Description of the Invention [Industrial Field of Application] The present invention includes a light projector that irradiates light onto an object to be measured, a filter having a narrow band transmission characteristic, and a filter that transmits light through the object to be measured and the filter. The present invention relates to a spectroscopic analyzer comprising a light receiving section that receives the light.

[Conventional technology]

Industrial applications of spectroscopic analyzers include, for example, sorting the ripeness of fruits. It is desirable that an analysis device used for such a purpose be simple and inexpensive.

Therefore, it is conceivable to irradiate the object to be measured with light and use the absorption of the spectrum at a specific wavelength of the transmitted light to analyze and determine the components.

At this time, in order to prevent errors due to changes in each part over time,
Component analysis may be performed based on the slope of the spectral intensity at the specific wavelength (hereinafter referred to as spectral differential value).

Conventionally, there have been the following configurations for easily obtaining spectral differential values.

In other words, multiple narrowband filters each having peak transmission characteristics at different wavelengths near a specific wavelength were prepared, and the spectral intensity at the peak wavelength of each filter was detected by a single photodetector while sequentially replacing the filters. .

Then, a spectral differential value was obtained based on the spectral intensity at each wavelength.

[Problem to be solved by the invention]

The above conventional technology has the following drawbacks.

In other words, since measurements must be made while sequentially replacing filters, measurement work cannot be carried out quickly and work efficiency cannot be increased.

Furthermore, it is necessary to prepare a plurality of filters having peak transmission characteristics at adjacent wavelengths.

An object of the present invention is to eliminate the above-mentioned conventional drawbacks and to obtain a spectroscopic analyzer that can obtain spectral differential values with high efficiency by using one filter.

[Means to solve the problem]

In order to achieve this object, the spectroscopic analyzer according to the present invention has a characteristic configuration in which the light receiving section is composed of a spectrometer that disperses the optical path in the order of the wavelength of the light, and an optical sensor that has resolution in the direction of the optical path dispersion. This is what is happening.

[For production]

By arranging an optical sensor having a plurality of light receiving elements such as a photodiode array on the spectral imaging plane of the spectrometer, it becomes possible to detect the spectral distribution of the transmitted light of the object to be measured.

The light receiving element of the optical sensor corresponding to the peak transmission wavelength of the filter can be easily identified by detecting the element with the highest received light intensity.

Therefore, the spectral differential value at the peak transmission wavelength can be obtained based on the received light intensity at the peak transmission wavelength and the received light intensity at a wavelength close to that wavelength.

〔Effect of the invention〕

By using one filter, spectral intensities at different wavelengths around a specific wavelength can be detected simultaneously, so a spectroscopic analysis device with high working efficiency can be obtained.

Furthermore, since it is possible to identify which element among the plurality of light receiving elements constituting the optical sensor is to be used for measurement based on the received light intensity, the assembly accuracy of the apparatus does not need to be very high. As a result, the device can be simplified.

〔Example〕

Hereinafter, an example in which the present invention is applied to fruit sorting based on sugar content will be described based on the drawings.

As shown in FIG. 4, a spectroscopic analyzer (1) for fruit sorting is installed on a conveyance line (L) that conveys fruits (F),
This constitutes a fruit sorting device. The spectrometer (1) is equipped with a photoelectric detection switch (2).
When the detection switch (2) detects a fruit (F), a fruit sorting operation is performed.

To further explain the spectroscopic analyzer (1), the first
As shown in the figure, a light projector (3) that irradiates light onto the object to be measured
, an interference filter (4) having narrow band transmission characteristics, and
It consists of a light receiving section (5) that receives the light transmitted through the object to be measured and the filter (4).

The light receiving section (5) includes a collimator (6) that outputs incident light as a parallel beam, and a prism (7) that serves as a spectrometer that disperses the optical path of the light from the collimator (6) in order of wavelength.
, the light dispersed by the prism (7) is sent to the optical sensor (9).
) and a photodiode array (9) as an optical sensor arranged to have resolution in the optical path dispersion direction of the light transmitted through the lens system (8) and the prism.
It consists of.

Add an explanation of the procedure for obtaining spectral differential values.

FIG. 2 shows the transmittance distribution of the filter (4). In other words, the light transmitted through the filter (4) in the absence of the object to be measured also exhibits a similar spectral distribution. still,
The concentration of chlorophyll, which has a correlation with the sugar content of fruit (F), has a correlation with light at a wavelength of 685 (nm). In other words, for example, when identifying chlorophyll or measuring its concentration, the peak transmission wavelength (λO)
It is sufficient to select a filter (4) having a value around 685 (nm).

In addition, an optical sensor (
The light receiving element (So) in 9) can be identified by detecting the element with the highest received light intensity.

Then, light receiving elements (31) and (St) located at a predetermined number of distances from the light receiving element (So) are selected. It is assumed that these light receiving elements (31) and (S2) correspond to wavelengths (A1) and (A2) that are close to the peak transmission wavelength (A0), respectively.

FIG. 3 shows an example of the spectral distribution on the spectral imaging plane, that is, the light receiving surface of the sensor (9). both of the light receiving elements (Si), (32) the respective light receiving intensities (AI);
(A2), both the light receiving elements (St
), (S2) The spectral intensity in each can be determined.

Then, the spectral differential value (D) at the peak transmission wavelength (A0) can be approximately determined by the following formula.

[Another example]

In the above example, the light receiving element (Sl) is located at a predetermined distance from the light receiving element (So) corresponding to the peak transmission wavelength (A0), the received light intensity (AI) of (S), and the spectrum from (Am) Although the differential value was calculated, the received light intensity (A
I), (A) and the received light intensity (Ao) at the peak transmission wavelength (A0) may be used to determine the spectral differential value (D). In that case, each wavelength (Ao).

Filter transmittance (KO), (Kl) in (A1)
It is also possible to correct the received light intensity (Ao) and (AI).

The present invention is applicable not only to fruits but also to the identification and concentration measurement of various components, such as the measurement of moisture and protein in substances.

In the above embodiment, a prism was used as a spectrometer, but
The specific configuration of each part can be changed in various ways, such as using a diffraction grating or Fabry-Perot.

Incidentally, although reference numerals are written in the claims section for convenient comparison with the drawings, the present invention is not limited to the structure shown in the accompanying drawings.

[Brief explanation of drawings]

The drawings show an embodiment of the spectroscopic analyzer of the present invention, FIG. 1 is a block diagram of the spectroscopic analyzer, FIG. 2 is an explanatory diagram showing the transmittance distribution of the filter, and FIG. 3 is the spectral distribution in the optical sensor. The explanatory diagram, FIG. 4, is a schematic plan view of the fruit sorting device. (3)... Light emitter section, (4)... Filter, (5)... Light receiving section, (7)... Spectrometer, (9 )... Light sensor.

Claims (1)

[Claims] A light projecting section (3) that irradiates light onto the object to be measured, a filter (4) having narrow band transmission characteristics, and a light receiving section (5) that receives the light that has passed through the object to be measured and the filter (4). ), wherein the light receiving section (5) comprises a spectrometer (7) that disperses the optical path in the order of the wavelength of the light, and an optical sensor (9) that has resolution in the direction of the optical path dispersion. A spectrometer consisting of: