JP2007271575A - Nondestructive measuring device of light scattering body - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To acquire excellent measurement accuracy, even when using a light scattering body having nonuniform inside scattering characteristic as a specimen, in a nondestructive measuring device of the light scattering body. <P>SOLUTION: This device includes a light source 8 for generating each irradiation light 10A, 10B, 10C having a plurality of wavelengths, an optical fiber cable 4 for emitting each irradiation light from an outgoing end face toward one-spot irradiation domain to the specimen 2 comprising the light scattering body, optical fiber cables 5, 6 having each incident end face on two or more positions respectively on each circumference of at least two concentric circles having mutually different diameters to the center of the outgoing end face, photodetectors 16, 17 for detecting the intensity of light received thereby, and an operation processing part for calculating a relative transmittance determined by taking the ratio of each light intensity detected thereby relative to each wavelength and calculating a property characteristic value inside the specimen based on the relative transmittance. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a non-destructive measuring apparatus for a light scatterer that uses a light scatterer as an object and measures its property characteristic value.

Conventionally, various non-destructive measuring devices for light scatterers are known which optically measure characteristic values related to the internal properties of a subject made of light scatterers, such as sugar content measurement of fruits and vegetables and blood glucose level measurement of humans. Yes.
For example, Patent Document 1 receives reflected light from a fruit or vegetable to be examined, measures an absorbance spectrum with respect to wavelengths in the near infrared region, calculates a second derivative value of these absorbance spectra, and calculates the result. Describes a sugar content measurement method and apparatus for estimating the sugar content of fruits and vegetables. Here, in order to estimate the fruit sugar content from the second derivative value of the absorbance spectrum obtained by the spectroscope, the second derivative value of the absorbance spectrum of the sample is correlated with the measured value of the sample sugar content in advance by the least square method ( This is called making a calibration curve), and the sample sugar content is estimated from the calculation result of the second derivative of the absorbance spectrum measured using the created calibration curve.
Further, Patent Document 2 irradiates the measurement site of fruits and vegetables with light in three different near-infrared wavelength regions, and receives each transmitted light transmitted through the measurement site of fruits and vegetables at two locations with different distances. The fruits and vegetables that detect the amount of transmitted light, calculate the relative transmittance that is the ratio of the amount of transmitted light of the same wavelength at the two detected locations for each wavelength, and calculate the sugar content of the fruits and vegetables using the relative transmittance of each wavelength A non-destructive sugar content measuring device is described.
JP-A-4-208842 (FIGS. 1 and 2) Japanese Patent Laying-Open No. 2004-317381 (FIGS. 1-4)

However, the conventional non-destructive measuring apparatus for light scatterers as described above has the following problems.
In the technique described in Patent Document 1, the sugar content is estimated using a calibration curve created by associating the second derivative of absorbance with the fruit sugar content, so that different varieties in the same kind of fruit, for example, apples, for example, Although the same calibration curve can be used for "Fuji" and "Starking", it is not a technique that can apply the same calibration curve to different types of fruits, and it is necessary to recreate the calibration curve for each fruit type There is. This is because the light irradiated to the fruit is scattered within the fruit, which is a scatterer, and propagates through the fruit, but the tissue structure is different even with the same sugar content depending on the type of fruit, and the absorbance detected by the different scattered light path lengths. Because it will be different.
In the technique described in Patent Document 2, the relative light transmittance of light received at two points at different distances is measured, and the scattered light path is calculated by using the relative absorbance ratio calculated from the relative transmittances of three different wavelengths. Although the error due to the difference in length can be reduced, this method is based on the theory of uniform light scatterers, and the measurement accuracy is low for the types of specimens whose scattering coefficients are not spatially uniformly distributed. There is a problem of getting worse. For example, a fruit with a scattering coefficient that is spatially approximately evenly distributed, such as apples, is highly accurate, but a scattering coefficient distribution is spatially inaccurate with a subject that has a tuft structure inside, such as a mandarin orange. There was a tendency for the measurement accuracy to deteriorate evenly.

  The present invention has been made in view of the above-described problems, and a light scatterer having a nonuniform internal scattering characteristic, for example, a light scatterer having a spatially nonuniform distribution of scattering coefficients is used as a subject. However, an object of the present invention is to provide a non-destructive measuring device for a light scatterer capable of obtaining good measurement accuracy.

In order to solve the above-described problem, in the invention according to claim 1, a light source that generates light of a plurality of wavelengths and a plurality of wavelength lights from the light source are irradiated at one place from a common light exit. A light irradiating unit that irradiates a subject made of a light scatterer toward the region, and at least different diameters with respect to the center of the light emitting port of the light irradiating unit in order to receive transmitted light from the subject At least two light receiving portions each having a light receiving opening at two or more positions on the circumference of two concentric circles; and a transmitted light detecting portion for detecting the light intensity of light received by the at least two light receiving portions;
An operation for calculating a relative transmittance obtained by taking a ratio of the light intensities of two light receiving portions having different concentric diameters for each of the plurality of wavelengths, and calculating a property characteristic value inside the subject based on the relative transmittance. And a processing unit.
According to this invention, at least two light receiving parts receive light transmitted from the light irradiation part to one irradiation region of the subject, and the transmitted light detection part receives the light intensity of each light receiving part. And calculates the relative transmittance, which is the ratio of the light intensities of two light receiving parts having different concentric circle diameters, for each wavelength from the light intensity of each light receiving part, and based on them, calculates the inside of the subject. The property characteristic value can be calculated. At that time, since the light receiving ports of at least two light receiving parts respectively have two or more light receiving lights on the circumference of each concentric circle, the light intensity at two or more positions at the same distance from the light emitting part is detected. Thus, the relative transmittance obtained by averaging each can be calculated. Therefore, it is possible to reduce measurement errors due to non-uniformity of scattering characteristics inside the subject.
The non-uniformity of the scattering characteristics inside the subject includes, for example, the non-uniformity of the spatial distribution of the scattering coefficient. In general, if there is non-uniformity and anisotropy in the structure and structure of the tissue inside the subject, non-uniformity in scattering characteristics often occurs.

According to a second aspect of the present invention, in the non-destructive measurement apparatus for a light scatterer according to the first aspect, the end of the light emitting unit on the light emitting port side and the light receiving port side of the at least two light receiving units. The end portion is configured to be integrally held by a fixed holding member that fixes the respective separation distances.
According to this invention, since the light emitting port of the light irradiating unit and the light receiving ports of the at least two light receiving units are integrally held by the fixed holding member with their respective separation distances fixed, Measurement can be easily performed with the distance kept constant.

According to a third aspect of the present invention, in the non-destructive measurement apparatus for a light scatterer according to the first or second aspect, each light receiving port of the at least two light receiving units is a plane perpendicular to the optical axis of the light irradiation unit. In FIG. 3, the light emitting ports are arranged so as to face each other across the center of the light emitting port on a straight line passing through the center of the light emitting port.
According to the present invention, each light receiving port of the light receiving unit is arranged on the straight line passing through the center of the light emitting port so as to face each other with the center of the light emitting port interposed therebetween. Measurement errors due to non-uniformity of the scattering characteristics of the scatterer can be reduced.

According to a fourth aspect of the present invention, in the non-destructive measurement apparatus for a light scatterer according to any one of the first to third aspects, the light receiving ports of the at least two light receiving units are orthogonal to the optical axis of the light irradiation unit. It is set as the structure arrange | positioned on the straight line which passes along the center of the said light-projection opening | mouth, and mutually orthogonally crosses in the plane to perform.
According to the present invention, the light receiving ports of the light receiving unit are arranged on straight lines that pass through the center of the light emitting port and are orthogonal to each other. Therefore, the non-uniformity of the scattering characteristic in the biaxial direction can be efficiently reduced.

According to a fifth aspect of the present invention, in the non-destructive measurement apparatus for a light scatterer according to any one of the first to fourth aspects, the light receiving ports of the at least two light receiving portions are substantially equidistant on each concentric circle. It is set as the structure arrange | positioned.
According to the present invention, since the light receiving ports of the light receiving section are arranged at substantially equal intervals on the respective concentric circles, the nonuniformity of the scattering characteristics in the circumferential direction of the concentric circles can be reduced substantially evenly.
Note that it is more preferable to make the arrangement interval on each concentric circle common, because the degree of equalization can be made constant regardless of the size of the concentric circle diameter.

According to a sixth aspect of the present invention, in the non-destructive measurement apparatus for a light scatterer according to any one of the first to fifth aspects, the light receiving ports of the at least two light receiving portions are each extended on a circumference of the concentric circle. It is constituted by at least one light receiving opening having an arc shape or a circular shape.
According to the present invention, since the light receiving port of the light receiving unit includes at least one light receiving port having an arc shape or a circular shape, it is possible to continuously receive light within the range of the opening lengths in the respective circumferential directions. . For this reason, the transmitted light can be received within the range. Therefore, the non-uniformity of the scattering characteristics in the circumferential direction can be further equalized as compared with the case where a plurality of circular light receiving ports are provided.
Here, the arc shape means an arc shape having a length that is twice or more the radial opening width of the light receiving opening. In this case, an effect equal to or greater than the case where two circular light receiving openings having a diameter corresponding to the opening width in the radial direction of the received light are arranged adjacent to each other can be obtained. It has a technical significance as a light receiving opening provided at two or more positions on the circumference of.

According to a seventh aspect of the present invention, in the non-destructive measurement device for a light scatterer according to any one of the first to sixth aspects, the transmitted light detection unit transmits light incident on a light receiving port of each of the light receiving units. A configuration is adopted in which detection is performed for each light receiving unit.
According to the present invention, since the light incident on the light receiving ports of the respective light receiving units is detected together for each light receiving unit, the configuration of the transmitted light detecting unit can be simplified.

According to an eighth aspect of the present invention, in the non-destructive measurement apparatus for a light scatterer according to any one of the first to sixth aspects, the transmitted light detection unit emits light incident on each light receiving port of each light receiving unit. The light intensity is detected for each light receiving port, and the light intensity for each light receiving part is calculated by calculating the light intensity.
According to the present invention, the transmitted light detection unit calculates the light intensity of each light receiving unit by calculating the light intensity after detecting the light intensity for each light receiving port in each light receiving unit. Accordingly, the light intensity at each light receiving opening can be calculated. For example, the average light amount can be obtained, or calibration can be performed for each light receiving port.

In the invention according to claim 9, in the non-destructive measurement device for a light scatterer according to any one of claims 2 to 8, the light emitting port of the light irradiation unit and the light receiving ports of the at least two light receiving units are: It is set as the structure arrange | positioned in alignment with the position of the surface of the said fixed holding member.
According to the present invention, since the light emitting port and the light receiving ports of the at least two light receiving portions are arranged in alignment with the surface position of the fixing holding member, the light emitting port and each light receiving port are arranged at the measurement position near the subject surface. Since the gap between the fixed holding member and the front of the fixed holding member does not occur when they are placed on the fixed holding member, even if the light from the subject is reflected by the fixed holding member, it is difficult to propagate and re-appears in the light receiving port. It becomes difficult to enter. Therefore, stray light can be reduced and measurement accuracy can be improved.

According to a tenth aspect of the present invention, in the non-destructive measurement apparatus for a light scatterer according to any one of the second to ninth aspects, the light emitting port of the light irradiation unit and the at least two of the fixed holding members. The surface on which the light receiving port of the light receiving unit is located has a light absorptivity.
According to this invention, the surface of the fixed holding member on which the light emitting port and the light receiving port are located has light absorption, so that the surface reflected light of the fixed holding member is reduced. Therefore, measurement accuracy can be improved.

In the invention according to claim 11, in the non-destructive measurement apparatus for a light scatterer according to any one of claims 1 to 10, the light irradiating unit has three or more wavelengths λ _i as the plurality of wavelength lights. (Where i = 1, 2,..., N, where n is an integer greater than or equal to 3), and the transmitted light detection unit has a radius of the concentric circle of the at least two light receiving units, ρ ₁ , When the total received light amount at the wavelength λ _i of the light received by the two light receiving units of ρ ₂ (where ρ ₁ <ρ ₂ ) is detected as J _1λi and J _2λi respectively, the arithmetic processing unit The relative transmittance R _λi for each wavelength λ _i represented by 1) is calculated, and the relative absorbance ratio γ _k (k = 1,..., M represented by the following formula (2), where m = n− 2) is calculated, the properties characteristic values, the m relative absorbance ratio _{γ k (k = 1, ...} , m) description A configuration which is adapted to calculate the calibration formula using a polynomial to several.
R _λi = J _2λi / J _1λi (1)
γ _k = ln (R _λk / R ₀ ) / ln (R ₁ / R ₀ ) (2)
Here, R ₀ and R ₁ are two different relative transmittances of R _λi , and R _λk (k = 1,..., M, where m = n−2) is R of R _λi . ₀ and m relative transmittances excluding R ₁ are represented.
According to the present invention, m relative absorbance ratios γ _k are calculated according to m wavelengths of light, and a calibration equation using a polynomial having relative absorbance ratios corresponding to m wavelengths as explanatory variables is used. Calculate property characteristic values.
In a uniform light scatterer, the relative absorbance ratio γ _{k in} equation (2) is theoretically the amount of light irradiated for measurement, ρ ₁ , ρ ₂ , Δ = (ρ ₂ −ρ ₁ ), light scattering. The amount does not depend on the equivalent scattering coefficient of the body. Therefore, when the non-uniformity of the scattering property of the light scatterer increases, the error due to the calibration formula using the relative absorbance ratio as an explanatory variable also tends to increase. However, in the present invention, the relative transmittance is at two locations on concentric circles. Since it is calculated from the total amount of received light at the above positions, the influence of the non-uniform scattering degree inside the subject is averaged according to each light receiving position, and estimation with less error can be performed.

  According to the non-destructive measuring apparatus for a light scatterer of the present invention, the total amount of light received at two or more positions on each of two concentric circles with different radii centered on the light irradiation part is detected at a plurality of wavelengths. By calculating the relative transmittance at positions separated by the concentric radius difference, measurement errors due to non-uniform scattering within the subject can be reduced, so that the scattering coefficient is spatially non-uniform. Even if a light scatterer distributed in the above is used as an object, an excellent measurement accuracy can be obtained.

  Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. In all the drawings, even if the embodiments are different, the same or corresponding members are denoted by the same reference numerals, and common description is omitted.

[First Embodiment]
A non-destructive measuring apparatus for a light scatterer according to a first embodiment of the present invention will be described.
FIG. 1 is a schematic configuration diagram showing a schematic configuration of a non-destructive measuring apparatus for a light scatterer according to a first embodiment of the present invention. FIGS. 2A and 2B are a side view and a cross-sectional view taken along line BB in FIG. 1 of the light receiving unit of the non-destructive measuring apparatus for a light scatterer according to the first embodiment of the present invention. is there. FIG. 3 is a graph showing the reflectance characteristic of the fixing holding member of the light receiving unit of the light scatterer nondestructive measuring apparatus according to the first embodiment of the present invention together with a comparative example. The horizontal axis represents wavelength (nm) and the vertical axis represents reflectance (%). FIG. 4 is a functional block diagram for explaining the functional configuration of the control system of the non-destructive measuring apparatus for light scatterers according to the first embodiment of the present invention.

As shown in FIG. 1, the nondestructive measuring apparatus 1 of the present embodiment optically determines a property characteristic value inside a subject 2 made of a light scatterer that scatters light incident from the outside and emits the light to the outside. The schematic configuration includes a light source unit 7, a sensor probe 3 (fixed holding member), a light detection unit 24, a signal processing unit 18, a central control unit 19, and a display unit 20.
As long as the subject 2 is a light scatterer having the property to be measured, any object may be used. Examples include fruits and vegetables, animals and plants such as living organisms, foods, beverages, soil samples, various quantitative analysis specimens, solid / powder / jelly / liquid samples, and the like.
The property characteristic value is a property value representing a property having a correlation with the degree of absorption with respect to incident light, and any property value can be used as long as a calibration equation can be set. For example, sugar and acidity of fruits and vegetables, blood sugar level, moisture content and protein content of flour, starch concentration such as potato, tissue oxygen saturation concentration of tissue, tissue hemoglobin oxidation degree, fertilizer component amount such as nitrogen in soil Characteristic values can be mentioned.
Further, the nondestructive measuring device 1 may be a device that measures one of such various property characteristic values, or may be a device that can switch and measure a plurality of property characteristic values. In the latter case, the measurer may manually set the property value to be measured, the measurement condition, etc. according to each measurement from the operation unit 21 (see FIG. 4) for performing operation input, or the same subject. A plurality of property characteristic values for 2 may be automatically and continuously performed.

Hereinafter, as an example, an example in the case where the sugar content of fruits and vegetables is measured will be described, and other light scatterers and characteristics specific to property characteristic values will be supplemented as necessary.
As an example of measurement, there may be cases such as Wenzhou mandarin oranges and apples. However, in this embodiment, even if the mandarin orange cannot be ignored in the internal tissue because the flesh is put in a bag for each bunch, the internal tissue Even in fruits and vegetables such as apples, pears, and melons with high uniformity, good measurement accuracy can be obtained using the same calibration formula, so the subject 2 is not limited to Satsuma mandarin and apples.

The light source unit 7 is for generating a plurality of wavelength lights. In the present embodiment, a plurality of wavelength lights to irradiate the subject 2, for example, λ ₁ = 1040 nm, λ ₂ = 940 nm, λ ₃ = 900 nm. It generates three wavelengths of light. These wavelengths are selected as an example of a combination of good wavelengths from the near infrared region in order to measure the sugar content. For example, when measuring the sugar content of fruits and vegetables, such a suitable wavelength can be set in the range of, for example, 800 nm to 1200 nm.
In order to generate these three wavelength lights, the light source unit 7 of this embodiment includes monochromatic light sources 8A, 8B, and 8C, a light source control unit 11, and coupling lenses 9A, 9B, and 9C.

The monochromatic light sources 8A, 8B, and 8C are light sources that oscillate wavelengths λ ₁ , λ ₂ , and λ ₃ , respectively. For example, a semiconductor laser or a light emitting diode can be used.
The light source control unit 11 includes a power source (not shown), and controls the light emission timing and light intensity of the monochromatic light sources 8A, 8B, and 8C independently by each light source in accordance with a control signal from the central control unit 19. It is.
In the present embodiment, a DC or modulated current is supplied to the monochromatic light sources 8A, 8B, and 8C so as to have a preset light emission intensity in synchronization with a clock signal having a fixed period received from the central control unit 19. Then, the control to turn on sequentially is performed.
The coupling lenses 9A, 9B, and 9C collect the lights emitted from the monochromatic light sources 8A, 8B, and 8C, respectively, and optically couple them to the optical fiber cable 4 to be described later as irradiation lights 10A, 10B, and 10C. It is an element.

  As shown in FIGS. 2A and 2B, the sensor probe 3 guides the irradiation lights 10A, 10B, and 10C generated by the light source unit 7 to the subject surface 2a of the subject 2, and the subject surface 2a. The optical fiber cables 4, 5 and 6 are fixed to the probe main body 3b having a cylindrical outer shape with a diameter φD.

As shown in FIGS. 1 and 2, the optical fiber cable 4 (light irradiating portion) is composed of three optical fibers 4b each having an exit end face 4a (light exit opening) at one end and an entrance end face 4c at the other end. The output end face 4a is aligned in the same position in the optical axis direction of the optical fiber and is bundled together in a certain region as viewed from the optical axis direction. The emission end face 4a is branched so as to be arranged at the imaging positions of the irradiation lights 10A, 10B, and 10C, respectively.
The combined emission end face 4a is fixed in the center of the probe end face 3a facing the subject surface 2a and aligned with the probe end face 3a. The optical axis on the emission end face 4a side of the optical fiber 4b is aligned with the normal direction of the probe end face 3a.

  Each of the optical fiber cables 5 and 6 (light receiving portion) is composed of eight optical fibers 5b and 6b each having an incident end surface 5a and 6a (light receiving port) at one end and an emission end surface 5c and 6c at the other end. Outgoing end faces 5c and 6c are bundled together in a state where they are aligned in the same position in the optical axis direction of the optical fiber and are bundled together in a certain region. On one end side, eight incident end faces 5a and 6a are respectively connected. It is branched so that it may be arrange | positioned in the light-receiving position, and is attached to the probe main body 3b. The optical axes on the incident end faces 5a and 6a side of the optical fibers 5b and 6b coincide with the normal direction of the probe end face 3a.

Eight incident end surface 5a from the central position of the exit end face 4a (light outlet center), are arranged evenly positions on the circumference of a radius [rho _1, are aligned on the probe face 3a on the same plane, respectively.
Eight incident end surface 6a from the center position of the exit end face 4a, are disposed evenly positions on the circumference of a radius [rho _2, are aligned to the probe face 3a on the same plane, respectively.
Here, ρ ₂ = ρ ₁ + Δ (where Δ> 0).
ρ ₁ , ρ ₂ , and Δ can be set as appropriate depending on the size of the subject 2, etc. In particular, the concentric circle radius ρ ₁ and the concentric circle radius difference Δ = ρ ₂ −ρ ₁ are Since it is easy to influence the measurement accuracy of the characteristic value, it is preferable to set from a range of values suitable for the measurement target. For example, in measuring the sugar content of fruits and vegetables, ρ ₁ and Δ are preferably 3 mm or more and 5 mm or more, respectively. The ρ ₁ and Δ upper limit values may be set as appropriate from the magnitude of the received light intensity on the incident end face 6a side. For example, in the measurement of sugar content of fruits and vegetables, 10 mm or less is suitable.

Further, the arrangement position in the circumferential direction between the incident end faces 5a and 6a is not particularly limited, but in the present embodiment, the incident end faces 5a and 5a at the opposite positions across the emission end face 4a, and the incident end faces 6a, 6a are aligned on the same diameter.
That is, the incident end faces 5a and 6a are arranged with good symmetry on the probe end face 3a with respect to the outgoing end face 4a, and are arranged at equal intervals in the circumferential direction of the incident end faces 5a and 6a. Therefore, the arrangement is such that light can be evenly received from the concentric measurement region centered on the emission end face 4a.

The fiber configurations and fiber materials of the optical fibers 4b, 5b, and 6b are preferably low in transmission loss. However, the calibration characteristic values such as the NA of the light receiving port and the transmission loss characteristic for each wavelength of the optical fiber are preferable. If it is known, there is no particular limitation. For example, multimode or single mode may be used, and the refractive index distribution may be an appropriate distribution. Further, glass fiber or plastic fiber may be used.
In the present embodiment, the optical fibers 4b, 5b, 6b are made to have a diameter of about φ1 by combining a plurality of core wires of φ0.2 mm. That is, this is an example in which the opening areas of the incident end faces 5a and 6a are the same.

It is preferable that the probe main body 3b is provided with light absorptivity so that the reflected light of the light from the subject 2 does not become measurement noise at least on the probe end surface 3a. Although the degree of light absorption depends on the required measurement accuracy, for example, in measuring the sugar content of fruits and vegetables, the reflectance is preferably 10% or less, and more preferably 5% or less. In order to facilitate calibration, it is preferable that the wavelength characteristics of the reflectance in the wavelength range used for measurement are substantially flat.
In this embodiment, the black grade of a polyacetal material is employ | adopted as a material which has such a favorable light absorptivity in a near infrared region.

FIG. 3 shows the reflectance wavelength characteristics of such a black grade polyacetal material together with a comparative example.
A curve 100 shows the reflectance characteristics of a black grade polyacetal material made from an acetal copolymer at a wavelength of 700 nm to 1200 nm.
As can be seen from FIG. 3, in this wavelength band, all have a substantially flat reflectance distribution of 5% or less.
On the other hand, as a comparative example, a curve 101 shows reflectance characteristics when the sensor probe 3 is made of an aluminum material and the probe end surface 3a is subjected to black alumite treatment.
The curve 101 increases as the wavelength increases in this wavelength range, and the reflectance is slightly over 60% at 1200 nm. Even in the wavelength range of the present embodiment, it is about 45% to 55%, which is an example in the case of not having good light absorption of 10% or less.

Of the light from the subject surface 2a, the light detector 24 is incident on the incident end faces 5a and 6a, propagates through the optical fibers 5b and 6b, and is transmitted through the exit end faces 5c and 6c. Condensing lenses 14 and 15 for condensing 12 and 13, respectively, and photodetectors 16 and 17 (transmitted light detection units) each having a light receiving surface disposed at each condensing position.
The photodetectors 16 and 17 may employ photodiodes having sufficient sensitivity to the wavelength light of the irradiation light 10A, 10B, and 10C.

The signal processing unit 18 amplifies the detection outputs of the photodetectors 16 and 17, calibrates the detection output based on a calibration value set in advance according to the wavelength characteristics of the photodetectors 16 and 17, and the incident end face This is converted into a digital signal converted into the total received light intensity in the light receiving ranges 5a and 6a and sent to the arithmetic processing unit 30.
In the following, the total received light amount corresponding to the wavelength λ _i (i = 1, 2, 3; the same _applies hereinafter) from the incident end face 5a is J _1λi , the average received light amount per light receiving area is I _1λi , and the same from the incident end face 6a. _These are denoted as J _2λi and I _2λi , respectively.
Here, the wavelengths of the transmitted lights 12 and 13 incident on the respective light sources are determined by automatically determining the wavelength switching timing of the light source controller 11 based on the clock signal transmitted from the central control unit 19.

The central control unit 19 controls the measurement operation of the nondestructive measuring apparatus 1, and is electrically connected to the light source control unit 11, the signal processing unit 18, the display unit 20, and the operation unit 21. Various control signals and data are communicated to control each operation.
The schematic functional block configuration includes an apparatus control unit 22, a display control unit 23, and an arithmetic processing unit 30, as shown in FIG.
The hardware configuration of the central control unit 19 may be configured by hardware that performs the operation of each function block, but is configured by a computer including a CPU, a memory, an input / output interface, an appropriate storage unit, and the like. A program corresponding to the operation of the block may be executed.

The device control unit 22 controls the operations of the light source control unit 11, the signal processing unit 18, the arithmetic processing unit 30, and the display control unit 23 in accordance with an operation input from the operation unit 21 operated by the measurer. Measurement start, end, measurement operation, and the like are performed.
To the light source control unit 11 and the signal processing unit 18, a control signal for controlling emission and detection processing of a plurality of wavelength lights is transmitted, and a clock signal for synchronizing each operation is transmitted.
A property characteristic value to be measured is notified to the arithmetic processing unit 30 in accordance with an operation input of the operation unit 21, and the processing operation of the arithmetic processing unit 30 is initialized.
The display control unit 23 performs control for sending information such as an operation input of the operation unit 21 and a measurement result sent from the arithmetic processing unit 30 to be displayed on the display unit 20.

  The display control unit 23 converts the information sent from the device control unit 22 into a video signal for display on the display unit 20.

The arithmetic processing unit 30 includes a relative transmittance calculating unit 31, a relative absorbance ratio calculating unit 32, a property characteristic value calculating unit 33, and a calibration formula data holding unit 34.
The relative transmittance calculator 31 calculates the relative transmittance R _λi from J _1λi and J _2λi sent from the signal processor 18 according to the above equation (1).

The relative absorbance ratio calculator 32 obtains the relative absorbance ratio γ ₁ from the relative transmittance R _λi calculated by the relative transmittance calculator 31 according to the following formula (2a).
γ ₁ = ln (R _λ1 / R ₀ ) / ln (R ₁ / R ₀ ) (2a)
Here, R ₀ and R ₁ are selected as follows.
R ₀ = R _λ3 (3)
R ₁ = R _λ2 (4)
Expression (2a) is an example in the case of n = 3 and m = k = 1 in the above expression (2).

Attribute property value calculating section 33, the gamma ₁ calculated by the relative absorbance ratio calculation unit 32, it is to calculate the sugar content C _s is a property characteristic values of the present embodiment by calibration formula which is expressed by the following equation.
C _s = β _s0 + β _s1 · γ ₁ (5)
Here, β _s0 and β _s1 are obtained by performing a single regression analysis using the relative absorbance ratio γ ₁ defined by the equation (2a) as an explanatory variable based on the result of an experiment performed on a sample having a known sugar content in advance. The estimated coefficient is called from the calibration formula data holding unit 34 by the property characteristic value calculation unit 33.
The sugar content C _s is sent to the apparatus control unit 22 after calculation.

The calibration formula data holding unit 34 stores a coefficient of a calibration formula obtained in advance in accordance with the property characteristic value to be measured. For example, the calibration formula data holding unit 34 is stored in a storage unit such as a ROM, an external storage medium, or an external storage unit. Composed.
When calculating the sugar content C _s , the above β _s0 and β _s1 are stored.

Next, the measurement operation of the nondestructive measuring apparatus 1 of the present embodiment will be described.
FIG. 5 is a schematic cross-sectional view of the vicinity of the measurement site of the non-destructive measurement apparatus for light scatterers according to the first embodiment of the present invention. 6 (a) and 6 (b) are cross-sectional explanatory views for explaining the directionality of measurement in the measurement of mandarin oranges. FIG. 7 is a schematic cross-sectional view of the vicinity of the measurement site for explaining the measurement when the light irradiation port and the light receiving port are not aligned with the probe end surface. Figure 8 is a graph illustrating an example of wavelength characteristics of absorbance when there is a gap amount delta _GAP between the light irradiation port and receiving port and the probe end face. The horizontal axis represents wavelength (nm) and the vertical axis represents absorbance. The absorbance on the vertical axis in FIG. 8 represents a value defined by the natural logarithm (−ln (R _λi )) of the reciprocal of the relative transmittance R _λi calculated according to the above equation (1). FIG. 9 shows the difference (ΔR) between the difference Δ between the concentric radii of the two light receiving portions calculated by the light diffusion theory and the relative reflectance R _λ and the amount of change δR _λ of R _λ per sugar content 1 (Brix%). / R) is a graph showing the relationship. The horizontal axis represents Δ (mm), and the vertical axis represents δR / R (%). FIG. 10 is a graph showing the relationship between the sugar content estimated by the non-destructive measurement apparatus for a light scatterer according to the first embodiment of the present invention and the measured value of a refractometer. The abscissa represents an actual measurement value of the fruit juice sugar content by a refractometer (PR-101, manufactured by Atago Co., Ltd., hereinafter), and the vertical axis represents an estimated value of the fruit sugar content by the apparatus of the present embodiment. In either case, the unit of sugar content is Brix%.

  In order to perform measurement with the nondestructive measuring apparatus 1, as shown in FIG. 5, the sensor probe 3 is brought into contact with or substantially in contact with the subject surface 2a at the measurement site of the subject 2. Deploy. Here, FIG. 5 is a schematic diagram, and the subject surface 2a is a flat surface. However, the subject surface 2a differs depending on the shape of the subject 2, and it goes without saying that, for example, a mandarin orange has unevenness and curvature. . Further, for the sake of clarity, a gap is provided between the probe end surface 3a and the subject surface 2a, but the arrangement may be such that a slight gap is provided so as to be substantially in contact with each other. You may make it contact. In the present embodiment, it is preferable that the exit end face 4a is in contact with the subject 2 or as close as possible to the subject 2 but the subject surface 2a and the entrance end faces 5a and 6a are not necessarily in contact with each other.

When the measurement start is input from the operation unit 21, the central control unit 19 sequentially turns on the monochromatic light sources 8 </ b> A, 8 </ b> B, and 8 </ b> C via the light source control unit 11. Irradiation lights 10A, 10B, and 10C having wavelengths λ ₁ , λ ₂ , and λ ₃ emitted from the light beams are respectively incident on the incident end surfaces 4c of the optical fiber 4b branched into three by the coupling lenses 9A, 9B, and 9C. Combined.
Then, the light propagates through each optical fiber 4b and is irradiated from the emission end face 4a located at the center of the probe end face 3a of the sensor probe 3 toward the subject surface 2a.

The light irradiated on the subject surface 2a is divided into reflected light reflected by the subject surface 2a and transmitted light that enters the subject 2 and passes through the inside.
The reflected light is repeatedly reflected and attenuated between the subject surface 2a and the probe end surface 3a.
The transmitted light is scattered by the properties inside the subject 2, passes through various optical paths, part of the light that reaches the subject surface 2 a again is emitted to the outside of the subject 2, and each incident end face 5 a, The light enters the optical fibers 5b and 6b at the position 6a, respectively.
For example, as shown in FIG. 5, light entering the right side and the left side of the figure is incident on the incident end face 5A (6A) and the incident end face 5B (6B) that are opposed to each other with the emission end face 4a interposed therebetween. 25A (26A) and internal light 25B (26B) enter.
The optical paths of these internal light scatter according to the internal properties of the subject 2 between the exit end face 4a and each entrance end face 5a (6a) and the distance between the exit end face 4a and the entrance end face 5a (6a). While transmitting. Therefore, the light intensity of the outgoing light from each includes information on the property of the subject 2 between the outgoing end face 4a and the incoming end face 5a (6a).
Therefore, the internal light 25A (26A) and the internal light 25B (26B) have a light intensity that reflects the difference in the properties in the horizontal direction in the drawing with respect to the emission end face 4a.

Similarly, for example, the light intensity of the internal light incident on the incident end surface 5C (6C) in FIG. 2A, which is a position obtained by rotating the incident end surface 5A (6A) by 90 °, is a property in the direction perpendicular to the paper surface in FIG. Contains information.
For example, as shown in FIGS. 6 (a) and 6 (b), the subject 2 is composed of a pulp part 200b in which the inside covered with the fruit skin part 200a is accommodated in a plurality of bag parts 200c. In this case, the cross section along the longitudinal direction of the bag portion 200c (see FIG. 6A) and the cross section crossing the bag portion 200c perpendicular to the bag portion 200c in the adjacent direction (see FIG. 6B) are scattered depending on the presence or absence of the bag portion 200c. The properties are completely different, and there are significant nonuniformities and anisotropy depending on the direction. Therefore, the incident end surface 5A (6A) and the incident end surface 5C (6C) arranged in the direction along each cross section include information according to the difference in properties such as the presence or absence of the bag portion 200c.
In the conventional non-destructive measurement technique, in the light scatterer having such a spatially non-uniform scattering characteristic, the measurement error varies depending on the arrangement position of the light irradiation port and the light receiving port.
As another example of the case where the subject 2 has such non-uniformity and anisotropy of the scattering characteristics, for example, muscle fibers having different scattering characteristics in the direction of stretching and the direction perpendicular to the muscles can be cited.

In the present embodiment, in this way, light including information on the internal properties of the subject 2 corresponding to the arrangement positions of the incident end faces 5a and 6a is transmitted by the optical fibers 5b and 6b, and is transmitted from the exit end faces 5c and 6c. Collectively, they are emitted as transmitted lights 12 and 13 respectively. Each transmitted light is collected by the condenser lenses 14 and 15 and received by the photodetectors 16 and 17.
The photodetectors 16 and 17 send detection output signals proportional to the received light intensity to the signal processing unit 18. This detection output is the sum of the total amount of light transmitted through each of the optical fibers 5b and 6b.

In the signal processing unit 18, the detection outputs of the photodetectors 16 and 17 are identified for each wavelength from the reception timing, and based on calibration information created in advance according to each wavelength, the total received light amount J _1λi for each wavelength, Convert to J _2λi .
Here, the calibration information is given as a correction coefficient for correcting the transmission loss of the optical fibers 5b and 6b, the transmittance of the condensing lenses 14 and 15 and the sensitivity characteristics of the photodetectors 16 and 17 for each wavelength.
Then, _assuming that the total received light amounts J _1λi and J _2λi for each wavelength are the light intensities I _1λi and I _{2λi obtained} by averaging the light receiving areas of the incident end faces 5a and 6a, I _1λi and I _2λi are calculated by the following equations. The
I _1λi = J _1λi / A ₁ (7)
I _2λi = J _2λi / A ₂ (8)
Here, A ₁ and A ₂ are the sum of the light receiving areas of the incident end faces 5a and 6a, respectively.

The relative transmittance calculator 31 calculates the relative transmittance R _λi for each wavelength λ _i according to the equation (1), and sends each calculation result to the relative absorbance ratio calculator 32.

Next, the relative absorbance ratio calculation unit 32 calculates the relative absorbance ratio γ ₁ according to the equation (2a), and sends it to the property characteristic value calculation unit 33. Here, the relative transmittance ratios R _λ1 / R ₀ and R ₁ / R ₀ of two different wavelengths expressed in the formula (2a) are represented by the following formulas from the definition of the formula (1).
R _λ1 / R ₀ = (J _2λ1 · J _1λ3 ) / (J _2λ3 · J _1λ1 ) (9)
R ₁ / R ₀ = (J _2λ2 · J _1λ3 ) / (J _2λ3 · J _1λ2 ) (10)
Further, using the relationship of the formulas (7) and (8), the formulas (9) and (10) are represented by the following formulas.
R _λ1 / R ₀ = (J _2λ1 · J _1λ3 ) / (J _2λ3 · J _1λ1 )
= (A ₁ · A ₂ · I _2λ1 · I _1λ3 ) / (A ₁ · A ₂ · I _2λ3 · I _1λ1 )
= (I _2λ1 · I _1λ3 ) / (I _2λ3 · I _1λ1 ) (9a)
R ₁ / R ₀ = (J _2λ2 · J _1λ3 ) / (J _2λ3 · J _1λ2 )
= (A ₁ · A ₂ · I _2λ2 · I _1λ3 ) / (A ₁ · A ₂ · I _2λ3 · I _1λ2 )
= (I _2λ2 · I _1λ3 ) / (I _2λ3 · I _1λ2 ) (10a)
From the expressions (9a) and (10a), the relative transmittance ratios of two different wavelengths are expressed as light intensities I _1λi and I _2λi averaged over the respective light receiving areas of the incident end faces 5a and 6a, and the light receiving areas A ₁ and A Does not depend on ₂ .

The property characteristic value calculation unit 33 calls the coefficients β _s0 and β _s1 of the calibration formula from the calibration formula data holding unit 34, and calculates the sugar content C _s according to the formula (5). Then, the calculation result is sent to the device control unit 22.
The device control unit 22 controls the display control unit 23 to output the sugar content Cs to the display unit 20.
Thus, the measurement of sugar content C _s non-destructive measuring apparatus 1 is completed.

As described above, in the present embodiment, since the incident end faces 5a and 6a are arranged at positions that equally divide the circumference of the concentric circle with the exit end face 4a as the center, from the positions that are equidistant from the exit end face 4a at ρ ₁ and ρ _2. Light emitted to the outside of the subject 2 can be received without deviation. Therefore, even if the scattering characteristics inside the subject 2 are non-uniform and the light intensities detected at the incident end faces 5a and 6a _vary , the sum of them is used as J _1λi and J _2λi. Since the relative transmittance R _λi is calculated, this relative transmittance averages the non-uniformity of the scattering characteristics inside the subject 2.
Therefore, the property characteristic value can be calculated with high accuracy using the equation (5), which is good for a light scatterer having spatially uniform scattering characteristics, as a calibration formula.

  Further, in the present embodiment, the pair of incident end faces 5a, 5a, 6a, 6a are arranged so as to face each other on the same straight line with the output end face 4a interposed therebetween, and asymmetry with respect to a plane orthogonal to the straight line. Is reduced well.

In the present embodiment, the probe end surface 3a, the emission end surface 4a, and the incident end surfaces 5a and 6a are aligned on the same plane, so that the influence of reflected light on the subject surface 2a is reduced. Can do.
For example, as shown in FIG. 7, to the probe end face 3a, emitting facet 4a, and each incident end face 5a, and the 6a, we are separated by a distance delta _GAP. Of the outgoing light from the outgoing end face 4a, the surface reflected light 27 reflected by the subject surface 2a is reflected by the probe end face 3a and re-enters the subject surface 2a, and the transmitted light or reflected light is incident. Incident on the end face 6A.
At this time, if _ΔGAP is large, light having a relatively small incident angle θ with high reflectivity reaches the vicinity of the incident end faces 5a and 6a with a small number of reflections, and becomes brighter noise light.
On the other hand, when _ΔGAP is small, light having a small incident angle θ has a large number of reflections, so that the number of reflections is significantly attenuated. Light having a large incident angle θ has a low reflectance, and therefore the attenuation is also large.
For example, FIG. 8 is an example of the measurement result of the wavelength characteristic of absorbance when _ΔGAP is changed. Curves 102, 103, and 104 show the measurement results when Δ _GAP = 0 mm, 5 mm, and 10 mm, respectively.
As can be seen from FIG. 8, in the measurement where _ΔGAP was set to 5 mm and 10 mm, the overall absorbance decreased, and in particular, the spectrum between 950 nm and 1000 nm observed when _ΔGAP = 0 mm significantly decreased. It can be seen that the measurement accuracy is greatly affected.
Thus, delta _GAP, as in the present embodiment, it is preferable to 0 mm.
Further, in this embodiment, since the light absorptive material having a reflectance of 5% or less over the measurement wavelength region is used, the influence of noise light can be further eliminated. Is.

Further, in the present embodiment, since the difference Δ between the concentric radii where the incident end faces 5a and 6a are arranged is set appropriately, good measurement accuracy can be obtained.
An appropriate value of Δ can be set by estimating the amount of change δR of the relative transmittance R _{λi with} respect to the unit change of the property characteristic value.
FIG. 9 shows a ratio (δR _λ / R _λ) of a relative transmittance R _λ and a change amount δR _λ of R _λ per 1 Brix% when δ is changed in the case of sugar content measurement. (represented as δR / R) was calculated using light diffusion theory and plotted with black circles. Here, λ = 940 nm, ρ ₁ = 10 mm, and the equivalent scattering coefficient of the subject 2 is 1.1 mm ⁻¹ .
Here, δR / R is an amount corresponding to the sensitivity of sugar content measurement, and as shown by the straight line 105, Δ and δR / R are in a good proportional relationship. That is, increasing Δ means that the amount of change in the relative transmittance R with respect to the change in sugar content, that is, the measurement sensitivity is increased. In general, when measuring the relative transmittance, a measurement sensitivity with a relative reflectance larger than the measurement error of the measurement apparatus is required. If the measurement accuracy of the relative transmittance of the measuring device is about 0.1%, it is necessary to set a distance Δ that provides a measurement sensitivity of 0.2% or more. That is, it can be seen from FIG. 9 that Δ ≧ 5 mm is required.

Next, a first measurement example of sugar content measured by the nondestructive measurement apparatus 1 will be described.
In this measurement example, the subject 2 was Satsuma mandarin, and the conditions of the sensor probe 3 were ρ ₁ = 3 mm, ρ ₂ = 10 mm, and Δ = 7 mm. Here, λ ₁ = 1040 nm, λ ₂ = 940 nm, and λ ₃ = 900 nm are used for _three different measurement wavelengths appearing in the equation (2a). In the calibration formula expressed by the equation (5), β _s0 = 0.963 and β _s1 = 0.0163 are used as the regression coefficients.
And after measuring the test object 2 with the nondestructive measuring apparatus 1 (estimated value), those fruit juices were squeezed and the sugar content was measured with the refractometer (actual value). These measured values were plotted in a scatter diagram as shown in FIG. 10 with the horizontal axis and the estimated value as the vertical axis.
As can be seen from FIG. 10, there is a good correlation between the measured values. The average error was 0.60 Brix%.
Therefore, according to the nondestructive measuring apparatus 1 of the present embodiment, it can be seen that even a subject having a non-uniform internal structure such as Satsuma mandarin can perform measurement equivalent to sugar content measurement by destructive inspection.

Next, a modification of this embodiment will be described.
FIGS. 11A, 11B, 11C, and 11D are side views of the light receiving unit used in the first to fourth modified examples of the first embodiment of the present invention in the A viewing direction in FIG. It is.

  As shown in FIGS. 11A, 11 </ b> B, 11 </ b> C, and 11 </ b> D, each modification of the present embodiment includes sensor probes 40, 41, 42, and 43 instead of the sensor probe 3. And the shape and configuration of the optical fiber cables 5 and 6 are changed accordingly.

The sensor probe 40 according to the first modified example is configured by arranging eight incident end faces 6a in the circumferential direction of the eight incident end faces 6a of the sensor probe 3 and arranging them at equal intervals on the same circumference (FIG. 11 (a)).
Therefore, since light can be received at a light receiving position with a finer pitch on the circumference of the radius ρ ₂ , transmitted light from the subject 2 having spatially non-uniform scattering characteristics can be further averaged. Measurement accuracy can be improved.

The sensor probe 41 of the second modified example is provided with arc-shaped incident end faces 41a and 41b (light receiving openings) along concentric circles in place of the incident end faces 5a and 6a of the sensor probe 3 (FIG. 11B). )reference).
The incident end faces 41a and 41b may be formed by increasing the number of cores of the optical fibers 5b and 6b and arranged in an arcuate region, or formed by an arcuate light guide member, and the optical fiber 5b. , 6b may be guided.
In this case, for example, by setting the circumferential lengths of the incident end faces 41a and 41b to be the same in proportion to the diameters of the concentric circles, the light receiving area ratio in the circumferential direction is made common, thereby spatially Transmitted light from the subject 2 having non-uniform scattering characteristics can be further averaged.

The sensor probe 42 of the third modified example includes ring-shaped incident end faces 42a and 42b (light receiving ports) that open along the circumferential direction on the respective concentric circles instead of the incident end faces 5a and 6a of the sensor probe 3 ( (Refer FIG.11 (c)).
In this modified example, all the transmitted light on the concentric circles can be received, so that the non-uniformity of the transmitted light from the subject 2 can be reliably ensured regardless of the spatial non-uniformity of the scattering characteristics. Can be equalized.

In the sensor probe 43 of the fourth modification, in addition to the incident end faces 5a and 6a of the sensor probe 3, the incident end faces 43a are arranged on the concentric circles having a radius ρ ₃ different from ρ ₁ and ρ _2, and the incident end faces 5a and 6a are arranged. Further, they are arranged on each straight line (see FIG. 11D). Although not particularly shown, the optical fiber that transmits the incident light of the incident end face 43a, a photodetector that detects the optical fiber, and the like are provided, and two light receiving units that calculate the relative transmittance are set by the setting from the operation unit 21. It is possible to select from three of the incident end faces 5a, 6a, and 43a.
The radius ρ ₃ is shown in FIG. 11D as an example in the case of ρ ₁ <ρ ₃ <ρ ₂ , but may be ρ ₃ <ρ ₁ , ρ ₂ <ρ ₃ , or the like.
According to this modification, three or more light receiving units are provided, and the relative transmittance can be calculated using the light intensity of the light received by two of the light receiving units. Therefore, the arrangement positions of the two light receiving portions and the radius difference Δ thereof can be selectively changed according to the type of the subject 2 and the type of property characteristic value. Therefore, the apparatus is suitable for general-purpose measurement.

Further, the number of light receiving apertures in the first embodiment and the modification is an example, and if it is two or more, an appropriate number can be arranged according to the type of subject and the required measurement accuracy. it can.
When the number of light receiving ports on one transmitted light detection unit is two, in order to efficiently average the non-uniformity of the scattering characteristics of the subject, the light beam is positioned at substantially opposite positions on a straight line passing through the center of the light emitting port. It is preferable to arrange them at positions where the straight lines passing through the centers of the two light receiving openings and the light exit opening are substantially orthogonal.
In order to be able to deal with a subject whose scattering characteristics are spatially non-uniform, it is preferable that at least four light receiving openings are arranged at positions that are substantially cross-shaped with respect to the center of the light exit opening.

[Second Embodiment]
A non-destructive measuring apparatus for a light scatterer according to a second embodiment of the present invention will be described.
FIG. 12 is a schematic configuration diagram showing a schematic configuration of a non-destructive measuring apparatus for a light scatterer according to a second embodiment of the present invention.

  As shown in FIG. 12, the nondestructive measuring device 50 (light scatterer nondestructive measuring device) of this embodiment is replaced with the light source 52 of the nondestructive measuring device 1 of 1st Embodiment, A light source unit 51 including a coupling lens 9 is provided, and an optical fiber cable 4A, a light source control unit 53, and a signal processing unit 60 are provided instead of the optical fiber cable 4, the light source control unit 11, and the signal processing unit 18, respectively. . Below, it demonstrates centering on a different point from the said 1st Embodiment.

The light source 52 is a white light source including light having a wavelength in the near infrared region. For example, a halogen lamp can be employed. However, the light source is not necessarily a white light source as long as it has a wavelength distribution in a band including wavelength light used for measurement.
The coupling lens 9 is an optical element that collects the white light emitted from the light source 52, optically couples it to the incident end face 4c, and enters the optical fiber 4b.

In the optical fiber cable 4A, the incident end face 4c side of the optical fiber cable 4 of the first embodiment is not branched into three.
The light source control unit 53 supplies voltage to the light source 52 in accordance with a control signal from the central control unit 19 and controls lighting with a predetermined light amount. However, in the present embodiment, since white light is lit, the wavelength switching control as in the first embodiment is not performed.

The signal processing unit 53 _splits the transmitted lights 12 and 13 emitted from the emission end faces 5c and 6c, and the total received light intensity J _1λi and J _2λi (i = 1, 1) 2,..., N, where n is an integer greater than or equal to 3. That is, the present embodiment is configured to obtain a plurality of wavelength lights by spectroscopically obtaining the transmitted light received by the light receiving port. Therefore, even if there is one light source, it is possible to easily acquire a plurality of wavelength lights.
Here, assuming that n = 3, a calibration formula similar to that in the first embodiment may be used, but an example in the case of n ≧ 4 will be described below.
The schematic configuration includes the condenser lenses 14 and 15, shutters 54 and 55, a prism 56, a diffraction grating 57, and a multi-channel detector 58 (light detection unit).

The shutters 54 and 55 are disposed on the optical paths of the transmitted lights 12 and 13 collected by the condenser lenses 14 and 15, respectively, and transmit one of the transmitted lights 12 and 13 and shield the other. It is a selection means.
The prism 56 is an optical path synthesizing unit that synthesizes the optical path of the transmitted light so that the light transmitted by the opening / closing operation of the shutters 54 and 55 can enter the diffraction grating 57 along a certain optical path. In the present embodiment, the transmitted light 13 is transmitted in the traveling direction, and the transmitted light 12 is reflected and combined in the same optical path as the transmitted light 13 after transmission.

The diffraction grating 57 is for performing the spectroscopy of the transmitted lights 12 and 13. The spectral wavelength range may be a range in which components of a plurality of wavelengths λ _i can be acquired.
The multi-channel detector 58 arranges a large number of light detection elements at positions corresponding to the diffraction angle on the optical path of the light diffracted by the diffraction grating 57, and acquires the respective light detection outputs, thereby allowing the spectral detection. A spectrum is acquired.
As the multi-channel detector 58, for example, a linear array sensor such as a CCD can be adopted.

Next, the measurement operation of the nondestructive measuring apparatus 50 will be described focusing on the differences from the first embodiment.
FIG. 13: is a graph which shows the relationship between the sugar content estimated with the nondestructive measuring apparatus of the light-scattering body based on the 2nd Embodiment of this invention, and the measured value of a refractive saccharimeter. The abscissa represents the actual value of the fruit juice sugar content measured by a refractometer, and the ordinate represents the estimated value of the apparatus of this embodiment. In either case, the unit of sugar content is Brix%.

Similarly to the first embodiment, the sensor probe 3 is arranged at the measurement site of the subject 2.
When the measurement start is input from the operation unit 21, the central control unit 19 turns on the light source 52 via the light source control unit 53. Then, white light having a wavelength in the near infrared region is emitted as irradiation light 10 and is optically coupled to the incident end face 4c of the optical fiber 4b by the coupling lens 9. Then, the light is irradiated from the emission end face 4a toward the subject surface 2a.

  The light irradiated on the subject surface 2a is transmitted into the subject 2, scattered and absorbed by the properties inside the subject 2, and reaches the subject surface 2a again through various optical paths. A part of the light is emitted to the outside of the subject 2 and enters the optical fibers 5b and 6b at the positions of the incident end faces 5a and 6a, respectively. At this time, the light incident on each optical fiber is scattered and absorbed according to the wavelength according to the internal properties of the subject 2 and becomes light having a spectrum including information on the internal properties.

In the signal processing unit 60, the transmitted lights 12 and 13 are sequentially incident on the diffraction grating 57 by operating the shutters 54 and 55. Then, the light intensity distribution of the light separated by the diffraction grating 57 is acquired by the multichannel detector 58. Then, transmission spectra S ₁ and S _{2 in} which each light receiving position is associated with a wavelength are acquired. Here, the transmission spectra S ₁ and S ₂ are preliminarily determined in accordance with the transmission loss of the optical fibers 5b and 6b, the transmittance of the condensing lenses 14 and 15 and the wavelength sensitivity characteristics of the multichannel detector 58 for each wavelength. Calibration is performed based on the created calibration information.
This makes it possible to calculate the total received light amounts J _1λi and J _2λi for all wavelengths in the spectral range. The calculated total received light amounts J _1λi and J _2λi are sent to the relative transmittance calculating unit 31.

The relative transmittance calculator 31 calculates the relative transmittance R _λi for each wavelength λ _i according to the equation (1), and sends each calculation result to the relative absorbance ratio calculator 32.
When an off-the-shelf spectrometer unit is used as the signal processing unit 60, the transmission spectrum S ₁ , S ₂ or the relative transmittance spectrum R (λ) = S ₂ / S ₁ is output to the relative transmittance calculating unit 31. The relative transmittance calculator 31 may acquire R _λi by acquiring a necessary wavelength component from R (λ).

Next, the relative absorbance ratio calculation unit 32 calculates a relative absorbance ratio γ _k according to the equation (2) and sends it to the property characteristic value calculation unit 33. In the present embodiment, R ₀ and R ₁ are represented by formulas (3) and (4). Therefore, m (= n−2) γ _k are calculated using the relative transmittance R _λi (i = 1,..., N) for n different wavelengths as shown in the following equation.
γ ₁ = ln (R _λ1 / R _λ3 ) / ln (R _λ2 / R _λ3 ) (11a)
γ ₂ = ln (R _λ4 / R _λ3 ) / ln (R _λ2 / R _λ3 ) (11b)
γ ₃ = ln (R _λ5 / R _λ3 ) / ln (R _λ2 / R _λ3 ) (11c)
・ ・ ・ ・
γ _m = ln ( _Rλn / _Rλ3 ) / ln ( _Rλ2 / _Rλ3 ) (11m)

The property characteristic value calculation unit 33 calls the coefficient β _{k of the} calibration formula from the calibration formula data holding unit 34 to calculate the property characteristic value C such as sugar content.
A calibration formula for estimating property characteristic values using a plurality of relative absorbance ratios γ _k can be obtained by multivariate analysis such as multiple regression analysis or PLS (Partial Least Square) regression analysis. For example, in the multiple regression analysis, the following equation can be used as a calibration equation.
C = β ₀ + β ₁ · γ ₁ +... + Β _m · γ _m (12)
Then, the calculation result is sent to the device control unit 22.
The device control unit 22 controls the display control unit 23 to output the property characteristic value C to the display unit 20.
Thus, the measurement of the property characteristic value C by the nondestructive measuring device 1 is completed.

As described above, in the present embodiment, the multi-channel detector 58 acquires the spectral spectrum, calculates the light intensity for each wavelength received by the light receiving port, and obtains the relative transmittance, thereby reducing the number of light sources 52. Can do. In addition, since it is not necessary to switch the irradiation of light with different wavelengths, the light intensity for each of a large number of wavelengths can be acquired in a short time, and the measurement efficiency can be improved.
In addition, since the property characteristic value is calculated by a calibration equation having two or more explanatory variables obtained by multivariate analysis such as multiple regression analysis using four or more wavelength lights, the measurement accuracy can be improved.
Since different wavelength lights have different optical paths, optical path ranges, and optical path lengths inside the subject 2, a calibration formula including two or more relative absorbance ratios using them has the same arrangement of the light receiving apertures. By selecting the wavelength, a wider range of information inside the subject 2 is included. Therefore, if the position and the number of the light receiving ports are the same, the estimation error due to the nonuniformity of the scattering characteristics of the subject 2 is reduced as compared with the case where the relative absorbance ratio is one as in the first embodiment. It is possible to achieve higher accuracy.

Next, a second measurement example of sugar content measured by the nondestructive measuring device 50 will be described.
As in the first embodiment, the conditions of this measurement example are the subject 2 mandarin orange, and the conditions of the sensor probe 3 are ρ ₁ = 3 mm, ρ ₂ = 10 mm, and Δ = 7 mm. As the calibration formula, the one obtained by PLS regression analysis is used. Here, the relative absorbance ratio spectrum γ (λ) = ln (R (λ) / R (λ ₃ )) / ln (R (λ ₂ ) / R (λ ₃ )) in the wavelength range 900 to 1070 nm is determined by PLS regression analysis. Three main components were selected and a calibration formula was created. However, λ is a wavelength excluding λ ₂ and λ ₃ , and the wavelength λ ₂ = 940 nm and λ ₃ = 900 nm.
And after measuring the test object 2 with the nondestructive measuring apparatus 50 (estimated value), those fruit juices were squeezed and the sugar content was measured with the refractometer (actual value). These measured values were plotted in a scatter diagram as shown in FIG. 13 with the horizontal axis and the estimated value as the vertical axis.
As can be seen from FIG. 13, the measured values have a good correlation. The average error was 0.53 Brix%.
Therefore, according to the nondestructive measuring apparatus 50 of the present embodiment, it is possible to perform a measurement equivalent to the sugar content measurement by the destructive inspection even for a specimen having a structure with spatially non-uniform scattering characteristics such as Satsuma mandarin. I understand. In addition, since a plurality of relative absorbance ratios are used, it is possible to perform measurement with higher accuracy than in the first embodiment.

Next, a third measurement example will be described. This measurement example is a measurement example that shows that a good measurement can be performed with the same calibration curve using the non-destructive measurement apparatus 50 according to the present embodiment even when different types of fruits are used as the subject 2.
FIG. 14 is a graph showing the relationship between the sugar content of another subject estimated by the non-destructive measurement apparatus for a light scatterer according to the second embodiment of the present invention and the measured value of a refractometer. The abscissa represents the actual value of the fruit juice sugar content measured by a refractometer, and the ordinate represents the estimated value of the apparatus of this embodiment. In either case, the unit of sugar content is Brix%.

In this measurement example, the subject 2 is an apple (San Fuji, Aomori), and the sensor probe 3 is ρ ₁ = 3 mm, ρ ₂ = 10 mm, and Δ = 7 mm. The calibration formula is the same as the calibration formula used in sugar content estimation of Unshu mandarin orange explained in the second measurement example.
As can be seen from FIG. 14, the measured values have a good correlation. The average error was 0.38 Brix%.
Therefore, according to the nondestructive measuring apparatus 50 of the second embodiment of the present invention, different kinds of fruits, here, Wenzhou mandarin oranges and apples can be estimated with high accuracy using the same calibration formula, Therefore, it is not necessary to re-create a calibration curve, so that it is very efficient in terms of operation of the measuring apparatus as compared with the prior art.
Such an effect cannot be obtained by a device that takes the second derivative of the relative transmittance of the prior art. In addition, since it is not necessary to take the second derivative of the relative transmittance, a simple configuration can be achieved as compared with such a conventional technique.

  In the above description of the first embodiment, the case where a plurality of wavelength lights is monochromatic light has been described. However, narrow band light having a sufficiently narrow band may be used instead of monochromatic light. Such narrow-band light can be easily obtained by using, for example, a band-pass filter.

  In the above description, the probe end surface 3 a is described as an example of a plane, but the probe end surface 3 a may be a curved surface that matches the shape of the subject 2. Alternatively, the probe end surface 3a may be made of a flexible material that can be deformed so that it can be deformed in accordance with its shape when the subject 2 is pressed. In these cases, the light emitting port and the light receiving port are easily brought close to the subject, so that measurement noise is reduced and better measurement accuracy can be obtained.

In the above description, the light from the light receiving ports on the same circumference is described as an example in which the light is detected by one transmitted light detection unit, but the light from each light receiving port is detected by a separate photodetector. Then, the detected output may be processed. For example, the sum may be taken or averaged.
In this case, it is good also as a structure which changed the magnitude | size of each light-receiving opening of each transmitted light detection part.
In each of the above embodiments, if the size of each light receiving port is changed in the same transmitted light detection unit, the light receiving area that divides the total amount of received light is the sum of the non-uniform opening areas in the circumferential direction. It is impossible to obtain I _1λi and I _2λi necessary for _obtaining . In such a case, the light from each light receiving opening is detected by a separate photodetector, the light intensity normalized by the opening area corresponding to each light receiving opening is obtained, and the sum of those is obtained to obtain the relative transmittance. I _1λi and I _2λi necessary for the _above are obtained.

  Moreover, if it is technically possible, all the components of each of the above-described embodiments and modifications can be appropriately combined and implemented within the scope of the technical idea of the present invention. For example, in the nondestructive measuring apparatus 1 of the first embodiment, a calibration formula using a plurality of relative absorbance ratios or a calibration formula using four or more relative transmittances in the second embodiment may be used.

It is a typical block diagram which shows schematic structure of the nondestructive measuring apparatus of the light-scattering body which concerns on the 1st Embodiment of this invention. FIG. 2 is a side view of the light receiving unit of the non-destructive measuring apparatus for a light scatterer according to the first embodiment of the present invention in the direction of view A in FIG. It is a graph which shows the reflectance characteristic of the fixing holding member of the light-receiving part of the non-destructive measuring apparatus of the light-scattering body which concerns on the 1st Embodiment of this invention with a comparative example. It is a functional block diagram for demonstrating the function structure of the control system of the non-destructive measuring apparatus of the light-scattering body which concerns on the 1st Embodiment of this invention. It is typical sectional drawing of the vicinity of the measurement site | part of the non-destructive measuring apparatus of the light-scattering body which concerns on the 1st Embodiment of this invention. It is sectional explanatory drawing for demonstrating the directionality of a measurement in the measurement of a mandarin orange. It is typical sectional drawing of the vicinity of the measurement site | part explaining the measurement when a light irradiation opening and a light-receiving opening are not aligned with the probe end surface. It is a graph explaining an example of the wavelength characteristic of a light absorbency in case there exists gap amount (DELTA) _GAP between a light irradiation opening and a light-receiving opening, and a probe end surface. Is calculated by the photon diffusion theory, it shows the difference Δ concentric radii of the two light receiving portions, the relationship between the amount of change &Dgr; R _lambda and the ratio of the relative reflectance R _lambda and per sugar _{1Brix% R λ (δR / R} ) It is a graph. It is a graph which shows the relationship between the sugar content estimated with the nondestructive measuring apparatus of the light-scattering body which concerns on the 1st Embodiment of this invention, and the measured value of a refractometer. FIG. 6 is a side view of the light receiving unit used in the first to fourth modifications of the first embodiment of the present invention in the A viewing direction in FIG. 1. It is a typical block diagram which shows schematic structure of the nondestructive measuring apparatus of the light-scattering body which concerns on the 2nd Embodiment of this invention. It is a graph which shows the relationship between the sugar content estimated with the nondestructive measuring apparatus of the light-scattering body which concerns on the 2nd Embodiment of this invention, and the measured value of a refractive saccharimeter. It is a graph which shows the relationship between the sugar content of the other test object estimated with the nondestructive measuring apparatus of the light-scattering body which concerns on the 2nd Embodiment of this invention, and the measured value of a refractive saccharimeter.

Explanation of symbols

1, 50 Non-destructive measuring device (Non-destructive measuring device for light scatterers)
2 Subject 3, 40, 41, 42, 43 Sensor probe (fixed holding member)
4 Optical fiber cable (light irradiation part)
4a Output end face (light exit)
5, 6 Optical fiber cable (light receiving part)
5a, 6a Incident end face (light receiving aperture)
8, 52 Light source 10, 10A, 10B, 10C Irradiation light 11 Light source controller 12, 13 Transmitted light 16, 17 Photodetector (transmitted light detector)
18, 60 Signal processor 19 Central control unit 24 Light detectors 25A, 25B, 25C, 26A, 26B, 26C Internal light 30 Arithmetic processor 31 Relative transmittance calculator 32 Relative absorbance ratio calculator 33 Property characteristic value calculator 34 Calibration data holding unit 54, 55 Shutter 56 Prism 57 Diffraction grating 58 Multi-channel detector (light detection unit)
200 oranges (subject)

Claims (11)

A light source that generates light of multiple wavelengths;
A light irradiation unit configured to irradiate a subject made of a light scatterer with a plurality of wavelength lights from the light source toward a single irradiation region from a common light exit;
In order to receive transmitted light from the subject, light receiving ports are provided at two or more positions on the circumference of at least two concentric circles having different diameters with respect to the center of the light emitting port of the light irradiation unit. At least two light receivers;
A transmitted light detector that detects the light intensity of light received by the at least two light receivers;
An operation for calculating a relative transmittance obtained by taking a ratio of the light intensities of two light receiving portions having different concentric diameters for each of the plurality of wavelengths, and calculating a property characteristic value inside the subject based on the relative transmittance. A non-destructive measuring device for a light scatterer comprising a processing unit.   The light emitting port side end of the light irradiation unit and the light receiving port side end of the at least two light receiving units are integrally held by a fixed holding member that fixes the respective separation distances. The non-destructive measuring device for a light scatterer according to claim 1.   The light receiving ports of the at least two light receiving units are arranged so as to face each other across a center of the light emitting port on a straight line passing through the center of the light emitting port in a plane orthogonal to the optical axis of the light emitting unit. The non-destructive measuring apparatus for a light scatterer according to claim 1 or 2, wherein:   The light receiving ports of the at least two light receiving units are arranged on straight lines that pass through the center of the light emitting port in a plane orthogonal to the optical axis of the light irradiation unit and are orthogonal to each other. The non-destructive measuring apparatus of the light-scattering body in any one of.   The non-destructive measuring device for a light scatterer according to any one of claims 1 to 4, wherein the light receiving ports of the at least two light receiving portions are arranged at substantially equal intervals on each concentric circle.   6. The light receiving openings of the at least two light receiving sections are each constituted by at least one light receiving opening having an arc shape or a circular shape provided so as to extend on a circumference of the concentric circle. The non-destructive measuring apparatus of the light-scattering body in any one of.   The light according to claim 1, wherein the transmitted light detection unit is configured to collectively detect light incident on a light receiving port of each light receiving unit for each light receiving unit. Non-destructive measuring device for scatterers.   The transmitted light detection unit detects light incident on each light receiving port of each light receiving unit for each light receiving port, and calculates the light intensity for each light receiving unit by calculating the light intensity thereof. The non-destructive measuring device for a light scatterer according to any one of claims 1 to 6.   9. The light emitting port of the light irradiation unit and the light receiving ports of the at least two light receiving units are arranged in alignment with the surface position of the fixed holding member. Non-destructive measuring device for light scatterers.   The surface on which the light emission port of the light irradiating unit and the light receiving ports of the at least two light receiving units are located in the fixed holding member has light absorptivity. The nondestructive measuring apparatus of the light-scattering body of description. The light irradiator is
Irradiating light containing three or more wavelengths λ _i (i = 1, 2,..., N, where n is an integer of 3 or more) as the plurality of wavelength lights;
The transmitted light detection unit is
Of the at least two light receiving parts, the total received light amount at the wavelength λ _i of the light received by the two light receiving parts having the concentric radii ρ ₁ and ρ ₂ (where ρ ₁ <ρ ₂ ) is _expressed as J _1λi , respectively. When detected as J _2λi ,
The arithmetic processing unit is
The relative transmittance R _λi for each wavelength λ _i represented by the following formula (1) is calculated,
The relative absorbance ratio γ _k (k = 1,..., M, where m = n−2) represented by the following formula (2) is calculated,
2. The property characteristic value is calculated by a calibration formula using a polynomial having the m relative absorbance ratios γ _k (k = 1,..., M) as explanatory variables. The non-destructive measuring device for a light scatterer according to any one of 10.
R _λi = J _2λi / J _1λi (1)
γ _k = ln (R _λk / R ₀ ) / ln (R ₁ / R ₀ ) (2)
Here, R ₀ and R ₁ are two different relative transmittances of R _λi , and R _λk (k = 1,..., M, where m = n−2) is R of R _λi . ₀ and m relative transmittances excluding R ₁ are represented.

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