JPH07301598A - Optical sensor probe - Google Patents

Abstract

PURPOSE:To provide a compact sensor probe for measuring a component actually contained in a sample using infrared rays without destructing the sample. CONSTITUTION:The optical sensor probe 2 comprises an integrating sphere for detecting a component actually contained in a sample, and projecting/ receiving optical fibers 3, 4, 4' The integrating sphere is provided, at one end in the diametral direction, with an incident port 10 for introducing infrared rays through the projection optical fiber 3. The integrating sphere is provided, at the other end in the diametral direction, with a detection window 5 for transmitting the infrared rays through a sample and passing a diffused reflection light from the sample. It is also provided with at least one port 14 for sampling the diffused reflection light from the sample and introducing the sampled light on the receiving optical fibers 4, 4' to the outside.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for measuring components contained in an object to be measured by infrared spectroscopic analysis as they are (hereinafter, this state is referred to as "existing type"), that is, without destroying the components. The present invention relates to an apparatus for measuring ingredients such as raw tea, a manufacturing intermediate, and water content of products.

[0002]

2. Description of the Related Art Measurement of components such as water contained in tea and food is indispensable for production and quality control.

When the sample is a powder, the components such as water contained therein can be measured by infrared diffuse reflectance spectroscopy, and several methods have been conventionally used as the measurement by this infrared spectroscopy. . One of them is to fill the measurement container with the sample to be measured, install it on the integrating sphere installed in the spectrophotometer, spectrally collect the light from the light source, irradiate the sample, and diffuse it from the sample. The reflected light is collected and received, and the component contained in the sample absorbs the infrared light of a specific wavelength, and the attenuation of the light intensity of that wavelength is measured from the received light and included in the sample. It is a method of measuring the components.

Another measuring method is to irradiate a sample with a fiber probe in which a fiber for guiding infrared rays to the sample and a fiber for guiding diffused reflected light from the sample are coaxial and inserted into the sample. Then, the diffuse reflection light from the sample is received, and the component contained in the sample is measured from the light intensity as in the above method.

The measurement by such infrared spectroscopic analysis is sufficient if the sample is a powder, and it is not necessary to destroy the sample as in the chemical analysis.

[0006]

However, if the sample is not a powder, the sample must first be dried and ground. In this way, so-called on-line measurement cannot be performed because the component composition of the sample changes, the measurement cost increases, and a crushing step is required. Therefore, for example, when making tea, it is desirable to measure the water content of the tea and adjust the drying process so that the water content is within the optimum range. , Crushing it and measuring the water content,
A smooth tea-making process cannot be carried out. Further, some samples are not suitable for crushing depending on the components contained in the samples. Conventional infrared diffuse reflectance spectroscopy cannot be performed on such samples.

Further, in the measurement using the integrating sphere, an integrating sphere is installed between the sample part and the detecting part of the infrared spectrophotometer, and the measuring container filled with the sample is fixed and measured there. It was complicated, large, and could not be used for online measurement in industrial equipment.

[0008] Therefore, an object of the present invention is to provide a sensor probe for measuring components contained in a sample in an existent form by using infrared rays without destroying the sample.

Another object of the present invention is to provide the above-mentioned compact sensor probe capable of on-line measurement of components contained in a sample.

A further object of the present invention is to provide a measuring device incorporating the sensor probe described above.

[0011]

The optical sensor probe of the present invention which achieves the above object comprises an integrating sphere for detecting a component contained in an existing sample, and a light projecting and receiving fiber. On the integrating sphere, the sensor probe has an entrance for introducing infrared rays at one end in the diametrical direction through a fiber optics, transmits the introduced infrared rays to the sample, and diffuses reflected light from the sample. It has a detection window at the other end in the diametrical direction for allowing the light to pass therethrough, and further has at least one sampling port for collecting the diffuse reflected light that has passed through the sample from the sample and leading it out to the outside by a light receiving fiber.

Here, the infrared rays may enter the integrating sphere through a collimator provided at the entrance, or may enter the integrating sphere by a rod-shaped member made of an optical material extending through the entrance to the detection window. Good.

An apparatus for detecting a component contained in an existent sample according to the present invention comprises a light source for generating infrared rays and an entrance for introducing infrared rays from the light source into the diametrical end by an optical fiber. Having a detection window at the other end of the diameter for transmitting the introduced infrared rays to the sample and transmitting the diffuse reflected light from the sample in the diffused reflected light transmitted from the sample to the inside. An integrating sphere having at least one sampling port which is sampled and led out by a light receiving fiber,
A splitter that splits the sampling light from the sampling port into two,
A detector that detects one of the split lights through a filter that passes the wavelength that the component to detect detects, and a detector that detects the other of the split light through a filter that passes the wavelength that the component to detect does not absorb. It is composed of a detector and an arithmetic means for calculating the component based on the light intensities obtained by the two detectors.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENT FIG. 1 schematically shows a substantially rectangular parallelepiped housing 1 in which an optical sensor probe 2 of the present invention is housed. The sensor probe 2 is composed of an integrating sphere as described below, and is provided with a projecting optical fiber 3 that guides infrared rays to the inside and light receiving fibers 4 and 4 ′ that guides light to the outside. A detection window 5 is provided on the bottom of the sensor probe 2.
(See FIG. 2) is provided, and that portion is exposed from the bottom of the housing 1 to the outside.

The housing 1 is suspended by wires, and the ends of the wires are connected to elevators 6 and 6'mounted on an external frame. The elevator is composed of a coil and a plunger, and pulls up the plunger by a magnetic force generated by energizing the coil. Therefore, the elevator can move the housing 1 up and down to move it away from or approach the sample 7. The elevator is not limited to this as long as it can raise and lower the housing. For example, a pneumatic cylinder may be used.

In order to measure the components of the sample according to the present invention, it is impossible to obtain a satisfactory measured value when the sample is full of gaps.
At the time of measurement, the housing 1 is lowered, and the weight of the sensor probe 2 itself and, if necessary, the weight (see FIG. 1) are adjusted, so that the sample 7 is pressed so as to be suitable for the measurement.

FIG. 2 shows a sectional view of the sensor probe 2. An entrance port 10 for introducing infrared rays is provided at the apex of the sensor probe 2, and a collimator lens system 11 is arranged therein. The infrared rays guided from the projection optical fiber 3 become parallel rays by the collimator lens system 11 and enter the inside.

A circular detection window 5 made of quartz is provided at the bottom of the sensor probe 2, that is, at a position facing the entrance 10. Infrared rays that have entered the inside pass through this detection window and are applied to the sample. The diameter of the detection window 5 passes through the detection window 5 through the collimator lens 11 and the sample 7
When the diameter of the light irradiated on is φ, φ + 6 mm is desirable.

The infrared light that has passed through the detection window 5 enters each of the samples, exits from there, passes through the detection window 5, and
The diffuse reflected light 12 enters the sensor probe 2. Here, a component in the sample absorbs infrared rays having a specific wavelength when the infrared rays are multiply scattered and transmitted through the sample. Therefore, the infrared rays of that wavelength are significantly attenuated and enter the sensor probe 2. Infrared rays having a wavelength not involved in such absorption enter the sensor probe 2 with almost no attenuation.

Collected diffused light 12 is collected in the upper hemisphere of the sensor probe 2 and sampling holes 14 and 1 for guiding it to the outside.
4'is provided. The diffusely reflected light 12 that has entered the inside from the detection window 5 is successively reflected by the sensor probe 2, that is, the inner wall of the integrating sphere, and reflected toward the sampling port 14 passes through the sampling port 14 and is connected to the receiving port. It is led out through the optical fibers 4, 4 '. The entrance 1
Of the light that enters inside from 0, there is some light that is specularly reflected on the surface of the detection window 5 and the sample interface of the window and does not enter the sample 7, but such light is reflected on the inner surface of the integrating sphere, Almost nothing goes to the sampling mouth. While such light also repeats reflection, it enters the sample 7 through the detection window 5 and becomes diffuse reflected light.

In this embodiment, the case where there are two sampling ports is illustrated, but when the direction of diffuse reflected light is uniform, there may be one sampling port. On the other hand, when the uniformity of the direction is poor, it is desirable to further provide a sampling port.

The sample 7 does not have to be in a fixed position and may be placed on the conveyor 8 and moved. However, if the moving speed is too fast, the noise of the detection light becomes large, so it is desirable to adjust the speed appropriately in accordance with the state of the detection light and the sample.

FIG. 3 shows a modification of the sensor probe of the present invention. Here, the same reference numerals as those in FIG. 2 are attached to the corresponding elements. In this sensor probe 30, the tip of the projection optical fiber 31 extends through the entrance 10 to the detection window and is embedded therein. When the fiber 31 is extended in this way, the incident light surely passes through the detection window and is irradiated onto the sample 7. Further, the specular reflection light generated at the interface between the fiber and the sample is not scattered inside the sensor probe 30. Therefore, the accuracy of this embodiment is very high. However, there is a problem in manufacturing when the detection window made of quartz is embedded at the tip of the projection optical fiber, and there is also a drawback that the manufacturing cost increases.

In this embodiment, the fiber 31 is a part of the throwing optical fiber, but not limited to this, a rod-shaped optical material such as quartz is provided between the entrance and the detection window, and the upper end of this rod-shaped material is provided. It may be configured by connecting projection optical fibers.

FIG. 4 is a block diagram showing an embodiment of a measuring device incorporating the present sensor probe. The light source 40 is
A light source that generates infrared light, preferably a light source that generates near-infrared light, the light generated by the light source 40 is focused by a lens 41, and light is modulated by a chopper 42. This chopper is not essential in such a measuring device. The modulated light is projected optical fiber 3 (or 31)
The light is projected onto the integrating sphere which is the sensor probe 2 (or 30) through the light. Then, the collected light is collected through the light receiving fiber 4 (or 4 ′) and passed through the collimator lens 43. The light converted into parallel rays by the collimator lens 43 is split into two by the beam splitter 44.

One of the divided lights is passed through a filter 45 which allows infrared rays in a specific band centered around a wavelength absorbed by a component to be measured contained in the sample to pass therethrough. The intensity of the passed light is detected by the detector 47. The detector 47 is preferably a PbS cell for near infrared rays. The detector 47 is appropriately cooled by an electronic cooler 48. The detected signal is amplified by the amplifier 49 and input to the arithmetic unit 53.

The other split light passes through the filter 47. The filter 47 passes infrared rays in a specific band centered on a wavelength that is not affected by absorption by the component to be measured. The passing light is detected by the detector 50, the detected signal is amplified by the amplifier 52,
It is input to the calculation unit 53. The detector 50 is also cooled by the electronic cooler 51. The output from the calculation unit 53 enters the output unit, where the quantity and graph are displayed.

In the calculation unit 53, the intensity of the infrared ray of the wavelength which is passed through the filter 45 and absorbed by the component to be measured and the intensity of the infrared ray of the wavelength which is passed through the filter 46 and is not influenced by the component to be measured. By comparing the above, the concentration of the component is calculated. In addition, the infrared ray passing through the filter 46 may be affected by the component, but in that case, an accurate concentration can be obtained by calibrating that portion in advance.

The power supply 54 supplies necessary power to the light source 40, the arithmetic unit 53, the electronic coolers 48 and 51, and the fan 55 for cooling the light source.

In this device, the concentrations of the components to be detected can be measured and measured by appropriately selecting the filters 45 and 46 that pass a specific wavelength.

As an example, the filter 45 having the following center wavelength when measuring the water content in a sample such as fresh tea, a simple product of tea production, and a tea product is given. When the concentration of water contained in tea, that is, the water content is 60% or more, the center wavelength is 1200 nm (half-value width 5 to 20 nm),
When the water content is 10 to 60%, the center wavelength is 1450n.
m (half-value width 5 to 20 nm) and a water content of 10 or less, the filter has a center wavelength of 1940 nm (half-value width 5 to 20 nm). Thus, changing the central wavelength depending on the water content is, for example, 19 when the water content is 50%.
This is because when a filter having a central wavelength of 40 nm is used, the light intensity to be detected is significantly attenuated and saturated, so that the water content cannot be measured. At this time, the center wavelength of the filter 46 is 1100 nm, 1250 nm, 18
Those of 50 nm and 2000 nm are used.

For components other than water, for example, hydrocarbons such as sucrose, starch and cellulose in the sample, the filter 4 is used.
The wavelengths of 5 are 1580 to 1590 nm and 1820 to 18
35 nm, or 2190-2200 nm, for fatty acids 1734 nm, 1765 nm, 2140 n
m, 2190 nm, 168 for proteins
0 nm, 2100 nm and 2180 nm.

[0033]

The sensor probe according to the present invention is composed of an integrating sphere, and the infrared ray is projected onto the integrating sphere and received by the fiber by a fiber, and further separated from the light source, the detector and the spectroscopic analysis system. Since it is compact, there is no problem such as temperature characteristics and noise due to electric signal conversion, and therefore highly accurate online measurement can be performed.

The measuring device using the present sensor probe is not limited to a powder sample, and a non-powder sample can be prepared by compressing the sample by utilizing the weight and weight of the probe. Since the shape can be measured as it is, online measurement can be performed. Furthermore, even if the sample moves, the measurement can be performed with almost no influence on the measurement.

[Brief description of drawings]

FIG. 1 shows a state in which a housing having a sensor probe of the present invention inside is pressed against a sample.

FIG. 2 shows a schematic cross-sectional view of the sensor probe of the present invention.

FIG. 3 shows a schematic sectional view of a sensor probe according to another embodiment of the present invention.

FIG. 4 is a block diagram showing an embodiment of the measuring apparatus of the present invention.

[Explanation of symbols]

 1 Housing 2 Sensor probe 3 Throw optical fiber 4, 4'Light receiving fiber 5 Detection window 6, 6 'Elevator 7 Sample 8 Belt conveyor 11 Collimator 10 Inlet port 12 Diffuse reflected light 14, 14' Sampling port 30 Sensor probe 31 Throw optical fiber 40 Light source 41 lens 42 chopper 43 collimator lens 44 beam splitter 45 filter 46 filter 47 detector 48 electronic cooler 49 amplifier 50 detector 51 electronic cooler 52 amplifier 53 arithmetic unit 54 power supply 55 fan

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[Procedure amendment]

[Submission date] December 28, 1994

[Procedure Amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0014

[Correction method] Change

[Correction content]

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENT FIG. 1 schematically shows a substantially rectangular parallelepiped housing 1 in which an optical sensor probe 2 of the present invention is housed. The sensor probe 2 is composed of an integrating sphere, as will be described below, and is provided with a projecting optical fiber 3 for guiding infrared rays to the inside and light receiving fibers 4, 4'for guiding light to the outside. A detection window 5 is provided on the bottom of the sensor probe 2.
(See FIG. 2) is provided, and that portion is exposed from the bottom of the housing 1 to the outside.

[Procedure Amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0016

[Correction method] Change

[Correction content]

In order to measure the components of the sample according to the present invention, it is impossible to obtain a satisfactory measured value when the sample is full of gaps.
At the time of measurement, the housing 1 is lowered and brought into contact with the sample, and further, the weight of the sensor probe 2 and further the weight (see FIG. 1) are adjusted, so that the sample 7 is pressed so as to be suitable for the measurement.

[Procedure 3]

[Document name to be amended] Statement

[Correction target item name] 0021

[Correction method] Change

[Correction content]

In this embodiment, the case where there are two sampling ports is illustrated, but when the direction of diffuse reflected light is uniform, there may be one sampling port. On the other hand, when the uniformity of the direction is poor, it is desirable to further provide a sampling port.

[Procedure amendment 4]

[Document name to be amended] Statement

[Correction target item name] 0034

[Correction method] Change

[Correction content]

The measuring device using the sensor probe of the present invention is not limited to a powder sample, and a non-powder sample is also brought into contact with the sample, and the probe's own weight, weight, etc. are used. Since the sample can be measured as it exists by compressing the sample, online measurement can be performed. Furthermore, even if the sample moves, the measurement can be performed with almost no influence on the measurement.

[Procedure amendment]

[Submission date] May 29, 1995

[Procedure Amendment 1]

[Document name to be corrected] Drawing

[Correction target item name] All drawings

[Correction method] Change

[Correction content]

[Figure 1]

[Fig. 2]

[Figure 3]

[Figure 4]

(72) Inventor Fumio Nakano 576-8 Shidoro, Kanaya-cho, Haibara-gun, Shizuoka Prefecture (72) Inventor Motohiro Nishimura 2-18-19 Kubo, Kakegawa City, Shizuoka Flower Bee 203

Claims (6)

[Claims] 1. An optical sensor probe comprising an integrating sphere for detecting a component contained in an existing sample, wherein infrared rays are introduced into one end of the integrating sphere at a diametrical end thereof by an optical fiber. Has an entrance port for transmitting infrared rays to be transmitted to the sample and transmitting diffused reflected light from the sample to the inside, and further has a detection window at the other end in the diametrical direction. Diffuse reflected light that has been transmitted is collected,
An optical sensor probe having at least one sampling port which is led out by a light receiving fiber. 2. The optical sensor probe according to claim 1, wherein a collimator is provided at the entrance, and infrared rays introduced by the projecting optical fiber become a condensed light flux and enter the integrating sphere. Characteristic optical sensor probe. 3. The optical sensor probe according to claim 1, wherein infrared rays are incident by a rod-shaped member made of an optical material that extends through the entrance to the detection window. 4. A device for detecting a component contained in an existing sample, comprising a light source for generating infrared light, and an entrance for introducing infrared light from the light source into one end in the diameter direction by an optical fiber. Having a detection window at the other end in the diametrical direction for transmitting the introduced infrared rays to the sample and transmitting diffuse reflection light from the sample into the inside, and further diffused from the sample to the inside. Collecting the reflected light and leading it out by the light receiving fiber, an integrating sphere having at least one sampling port, a splitter for splitting the sampling light from the sampling port into two, and one of the split light, A detector that detects through a filter that passes the wavelength that the component to detect detects, and a detector that detects the other of the split light through a filter that passes the wavelength that the component to detect does not absorb When an arithmetic means for calculating the component based on the light intensity detected by the two detectors consists of unit. 5. The apparatus according to claim 4, wherein a collimator is provided at the entrance, and the infrared light introduced by the projection optical fiber becomes a condensed light flux and enters the integrating sphere. Device to do. 6. The device according to claim 4, wherein infrared rays are incident by a rod-shaped member made of an optical material that extends through the entrance to the detection window.