Optical measurement tool, optical measurement device, and optical measurement method

Abstract

To provide an optical measurement tool, an optical measurement device, and an optical measurement method which achieve easy and accurate measurement in near infrared spectroscopy.SOLUTION: An optical measurement tool 1 is used in near infrared spectroscopy for detecting near infrared light reflected or transmitted by a measurement object S by using a sensor main body 5 which includes an irradiation part 51 for irradiating the measurement object S filled in a container 6 with the near infrared light. The optical measurement tool includes: a pedestal member 2 having a placement surface 22 on which the container 6 is placed horizontally and a recess part 23 which is recessively arranged in the placement surface 22 and in which the sensor main body 5 is mounted in such a manner that the irradiation part 51 faces upward; and a lid member 3 covering the placement surface 22 together with the container 6.SELECTED DRAWING: Figure 4

Description

Technical Field

[0001] The present invention relates to an optical measurement jig, an optical measurement device, and an optical measurement method used in near-infrared spectroscopy.

Background Art

[0002] In recent years, near-infrared spectroscopy (NIR method) has been widely used as a method for analyzing samples. Near-infrared spectroscopy is a technique for irradiating a sample with near-infrared light and obtaining information about the physical or chemical properties of the sample from the spectrum of the reflected light or transmitted light obtained. For example, it is possible to predict the content of a specific component in a sample in a short time without destroying the sample.

[0003] For example, in Patent Document 1, light having a wavelength in the range of 400 nm to 2500 nm or a partial range thereof is irradiated onto foods such as vegetables, fruits, or meats to be inspected, and the reflected light, transmitted light, or transmitted reflected light is detected to obtain absorbance spectrum data. Then, the absorbance at the entire measurement wavelength or a specific wavelength therein is substituted into a previously created measurement model to quantitatively or qualitatively analyze the components in the food. This method is said to be easy to measure because raw leaves such as vegetables can be directly used as the measurement target.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] Near-infrared spectroscopy is a non-destructive analytical method with excellent operability and capable of rapid measurement, and is used in a wide range of fields such as the food field, agricultural field, and industrial field. On the other hand, in order to measure the target components with high precision, repeatability is important. However, in conditions with a lot of on-site disturbances (such as measurement techniques and external light), the measurement results may vary, making it difficult to perform high-precision measurements.

[0006] The present invention has been made in view of such circumstances, and an object thereof is to provide an optical measurement jig, an optical measurement device, and an optical measurement method that are simple and can be measured with high accuracy in near-infrared spectroscopy.

Means for Solving the Problems

[0007] The optical measurement jig of the present invention uses a sensor body having an irradiation unit that irradiates near-infrared light onto a measurement object filled in a container, and is used in near-infrared spectroscopy for detecting near-infrared light reflected or transmitted by the measurement object. The optical measurement jig includes a pedestal member having a placement surface on which the container is horizontally placed and a concave portion that is recessed from the placement surface and on which the sensor body is mounted with the irradiation unit facing upward, and a lid member that covers the placement surface together with the container. In the present invention, reflection includes diffuse reflection.

[0008] In the pedestal member, the concave portion is formed such that the position of the irradiation unit of the sensor body is eccentric from the center position of the container in a plan view. The center position of the container in a plan view is, for example, the center of the circle when the container is a petri dish.

[0009] The optical measurement jig further includes a flat spacer member in which a through hole into which the container can be fitted is formed. The spacer member is placed on the placement surface together with the container and restricts the movement of the container placed in the through hole. Further, the spacer member is a black member.

[0010] The pedestal member has a notch in a part of its outer peripheral surface, and the spacer member has a locking portion that locks into the notch.

[0011] The optical measurement device of the present invention includes a sensor body having an irradiation unit that irradiates near-infrared light onto a measurement object filled in a container, and is an optical measurement device that detects near-infrared light reflected or transmitted by the measurement object. The optical measurement device includes a pedestal member having a placement surface on which the container is horizontally placed and a recess that is recessed from the placement surface and on which the sensor body is mounted with the irradiation unit facing upward, and a lid member that covers the placement surface together with the container.

[0012] The optical measurement method of the present invention is a method of performing near-infrared spectroscopy using the optical measurement device of the present invention, and is characterized by quantifying the content of components contained in the measurement object based on near-infrared light reflected or transmitted by the measurement object.

Advantages of the Invention

[0013] The optical measurement jig of the present invention is a jig used for near-infrared spectroscopy, and includes a pedestal member having a placement surface on which a container filled with a measurement object is horizontally placed and a recess that is recessed from the placement surface and on which a sensor body is mounted with the irradiation unit facing upward, and a lid member that covers the placement surface together with the container. Therefore, the position of the container with respect to the sensor body can be stabilized, and in a state where the lid is covered with the lid member, near-infrared light can be irradiated onto the measurement object and near-infrared light reflected or the like can be detected. Thus, while having a simple structure, disturbances can be effectively reduced. As a result, measurement can be performed simply and accurately.

[0014] In the pedestal member, the recess is formed such that the position of the irradiation unit of the sensor body is eccentric from the center position of the container in a plan view. Therefore, for example, when repeatedly measuring by changing the irradiation position of the measurement object, the irradiation position can be changed by rotating the container, and the operability can be improved while stabilizing the position of the container with respect to the sensor body.

[0015] The above optical measurement jig further includes a flat spacer member having a through hole into which the container can be fitted. Since the spacer member is placed on the placement surface together with the container and restricts the movement of the container placed in the through hole, it is easy to stabilize the position of the container during measurement. Further, since the spacer member covers the area other than the container on the placement surface, disturbances can be further reduced. Furthermore, since the spacer member is a black member, the spacer member easily absorbs light and is more likely to reduce the influence of external light.

[0016] The optical measurement device of the present invention includes a sensor body having an irradiation unit, a pedestal member having a placement surface on which the container is horizontally placed and a recess provided recessed from the placement surface and on which the sensor body is mounted with the irradiation surface facing upward, and a lid member that covers the entire placement surface including the container. Therefore, measurement can be performed simply and accurately.

[0017] The optical measurement method of the present invention is a method of performing near-infrared spectroscopy using the optical measurement device of the present invention. Based on the near-infrared light reflected or transmitted by the measurement object, the content of the components contained in the measurement object is quantified. Therefore, the content of the component can be accurately quantified (predicted) and can be used for identification and determination of the measurement object.

Brief Description of the Drawings

[0018]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Mode for Carrying Out the Invention

[0019] The optical measurement jig of the present invention is used in near-infrared spectroscopy. Specifically, it is used for qualitative and quantitative analysis of components contained in a measurement object, and for judging the properties of the measurement object. Near-infrared spectroscopy utilizes the phenomenon that when a molecule absorbs light energy in the near-infrared region, its vibration or rotational state changes. The measurement object may be any object that can be analyzed by infrared spectroscopy, and there are a wide variety.

[0020] Hereinafter, the optical measurement jig of the present invention and the like will be described with reference to the drawings.

[0021] FIG. 1 is an overall perspective view of the optical measurement jig. As shown in FIG. 1, the optical measurement jig 1 has a pedestal member 2 and a lid member 3 as main constituent members. In FIG. 1, the pedestal member 2 and the lid member 3 are each circular in plan view, and the lid member 3 covers the pedestal member 2 on which the sensor body 5 is mounted, and the overall shape of the optical measurement jig 1 is substantially cylindrical. The optical measurement jig 1 further has a spacer member 4.

[0022] Examples of the materials of the pedestal member 2 and the lid member 3 include polyolefin resins such as polypropylene and polyethylene, polyester resins such as polyethylene terephthalate, polycarbonate resins, polyamide resins, and resins such as ABS resin. Note that the pedestal member 2 and the lid member 3 may be made of the same material or different materials.

[0023] As shown in FIG. 1, the pedestal member 2 has a notch 21 in a part of its outer peripheral surface 2a. In FIG. 1, the notch 21 is connected to a recess described later, and the connection cord of the sensor body 5 is drawn out from this open part. The connection cord is connected to a processing device (analysis unit).

[0024] The sensor body 5 has at least an irradiation unit that irradiates near-infrared light. The wavelength range of the near-infrared light irradiated from the irradiation unit is, for example, 800 nm to 2500 nm, may be 1200 nm to 2500 nm, or may be 1500 nm to 2300 nm. The wavelength range of the near-infrared light is preferably set appropriately according to the measurement object. As the light source of the irradiation unit, for example, a halogen lamp or the like is used.

[0025] For example, the sensor body 5 has an irradiation unit and a detection unit that detects the near-infrared light reflected or transmitted by the measurement object. The detection unit is constituted by, for example, a semiconductor element such as a CCD (Charge Coupled Device). In the present invention, the shape and specifications of the sensor body are not particularly limited, and various types can be used as long as they can be mounted on the pedestal member. In each drawing, as an example, a substantially rectangular parallelepiped shape is shown. A commercially available compact spectroscopic module or the like can be used for the sensor body 5.

[0026] In FIG. 1, a configuration in which at least the sensor body 5 is added to the optical measurement jig 1 corresponds to the optical measurement device in the present invention.

[0027] Next, the configuration of the pedestal member 2 will be described with reference to FIG. 2. FIG. 2(a) is a plan view of the pedestal member, FIG. 2(b) is a side view as viewed from arrow A, and FIG. 2(c) is an end view taken along line B-B. As shown in FIG. 2(a), the pedestal member 2 is circular in plan view and has a mounting surface 22 on the upper part. The mounting surface 22 is formed as a flat surface, and a container is placed on at least a part of the region of the mounting surface 22. The outer edge of the mounting surface 22 is formed in an arc shape and is partitioned by a peripheral wall 24 erected from the mounting surface 22. In FIG. 2, the peripheral wall 24 is formed in an arc shape except at the location where it is divided into the recess 23. The height t of the peripheral wall 24 is smaller than the depth d of the recess, and as a specific numerical value, for example, it is 2 mm to 10 mm.

[0028] As shown in Fig. 2, the pedestal member 2 has a recess 23 that is recessed in the vertical direction from the mounting surface 22. The recess 23 is the portion where the sensor body is mounted. In Fig. 2, the recess 23 is formed in a groove shape so as to form a rectangular parallelepiped volume according to the shape of the sensor body. One end side of the recess 23 penetrates the outer peripheral surface 2a of the pedestal member 2, and the opened portion constitutes a notch 21. In other words, the recess 23 extends linearly from one location in the circumferential direction of the outer peripheral surface 2a toward the opposing position, and is formed beyond the center position O of the pedestal member 2 in plan view. Note that the other end side of the recess 23 does not penetrate to the outer peripheral surface 2a and is closed. The notch 21 is a portion cut out from the upper end of the pedestal member 2 and communicates with the recess 23.

[0029] The depth d of the recess 23 is set to be larger than the height of the sensor body. Therefore, the mounted sensor body does not protrude upward from the mounting surface 22, and the container can be horizontally mounted on the mounting surface. The depth d of the recess 23 is preferably set according to the height dimension of the sensor body.

[0030] As shown in Fig. 2(c), a through hole 25 is formed in the bottom surface of the recess 23. The through hole 25 is a screw hole, and the sensor body and the pedestal member 2 are fixed by a fixture such as a screw through this through hole 25. In particular, when storing the sensor body mounted on the pedestal member 2 for a long period of time or when carrying them, fixing by a fixture is preferable. The position and number of the through holes are not limited and can be formed according to the shape of the sensor body. Note that the through hole 25 may not be provided in the pedestal member 2.

[0031] Fig. 3(a) shows the state where the sensor body is attached to the pedestal member 2. As shown in Fig. 3(a), in the recess 23, the sensor body 5 is attached with the irradiation unit 51 facing upward. The irradiation unit 51 has a light source that irradiates near-infrared light and also has a detection unit (sensor unit) that detects the near-infrared light reflected by the measurement object. The recess 23 is preferably formed such that the position of the irradiation unit 51 of the sensor body 5 is eccentric from the center position O in the plan view of the pedestal member 2 (also from the center position P in the plan view of the container 6). In this case, the irradiation unit 51 and the center position O do not overlap in the plan view.

[0032] Subsequently, Fig. 3(b) shows the state where the spacer member is placed from the state of Fig. 3(a). The spacer member 4 is a flat plate-like member with a thickness of about 2 mm to 10 mm, and a through-hole 41 into which the container 6 can be fitted is formed inside. The shape and size of the through-hole 41 are preferably set according to the shape and size of the container 6. Generally, a petri dish is used as the container for filling the measurement object, and in Fig. 3(b), the through-hole 41 is circular to match the shape of the petri dish.

[0033] The spacer member 4 is placed on the placement surface 22 and is a member that covers the area other than the area where the container 6 is placed on the placement surface 22. In Fig. 3(b), the outer edge of the spacer member 4 is in an arc shape following the outer edge of the placement surface 22. The spacer member 4 is placed together with the container 6 and serves to restrict the movement of the container 6 placed in the through-hole. Also, the spacer member 4 can fill the periphery of the space between the container 6 and the irradiation unit 51 and make the space a closed space as much as possible, thereby reducing the influence of external light more effectively.

[0034] Further, the spacer member 4 has a locking portion 42 that locks into the notch 21 formed in the pedestal member 2. The locking portion 42 is formed at one location in the circumferential direction of the spacer member 4 and is formed to protrude radially outward. The locking portion 42 functions as a rotation stopper for the spacer member 4, and by protruding radially outward, it makes it more difficult for external light to enter the space between the container 6 and the irradiation unit 51. Also, when attaching the spacer member 4, it can be easily attached by gripping the locking portion 42 and hooking it onto the notch 21.

[0035] In addition, in FIG. 3, the notch 21 is provided at one location in the circumferential direction, but the present invention is not limited to this configuration, and it may be provided at a plurality of locations. Also, in a configuration where the recess 23 does not open to the outer peripheral surface 2a, it may be formed separately from the recess 23. For example, the locking portions 42 of the spacer member 4 may be provided at a plurality of locations according to the form of the notch.

[0036] As shown in FIG. 3(b), the position of the irradiation unit 51 of the sensor body 5 is offset from the center position P in plan view of the container 6 (which is also the center position in plan view of the through-hole 41). The offset distance is, for example, about 10 mm to 30 mm. In this case, when the container 6 is placed so as to fit into the through-hole 41, since the irradiation unit 51 is displaced from the center position P in plan view of the container 6, the irradiation position of the measurement object can be easily changed by rotating the container 6.

[0037] Also, regarding the spacer member 4, the center position in plan view of the through-hole 41 is offset from the center position of the arc-shaped outer edge. In FIG. 3(b), the direction of this offset is the direction away from the formation position of the locking portion 42.

[0038] The material of the spacer member 4 is not particularly limited, and the various resins described above can be used. In particular, the spacer member 4 is preferably a black member. In this case, the spacer member 4 may be molded from a resin material colored black, or a black coating may be applied to the surface of the resin molded body. By making the spacer member 4 a black member, it is easy to absorb light, and the influence of external light can be further reduced.

[0039] Figure 4 shows a schematic diagram when measuring using the optical measurement device of the present invention. Figure 4 is a schematic diagram seen from the opening side of the outer peripheral surface of the pedestal member. As shown in Figure 4, the sensor body 5 is mounted in the recess 23 of the pedestal member 2, and a container 6 filled with the measurement object S is placed above the irradiation unit 51 of the sensor body 5. Further, the spacer member 4 is placed on the placement surface 22 together with the container 6. Then, the lid member 3 is placed so as to cover the placement surface 22 together with the container 6. In this covered state, measurement by near-infrared spectroscopy is performed.

[0040] As the container 6, for example, a glass petri dish is used. Note that it is not limited to a circular shape, and a square glass container may also be used. It is preferable to set the distance from the surface of the irradiation unit 51 to the bottom surface of the container 6 to be as small as possible.

[0041] As the measurement object S, for example, wood, herbs, foods, drugs, biological tissues, etc. can be used. The state of the measurement object S may be solid, powder, liquid, paste, etc., and may be pulverized as necessary. Also, the components to be targeted for quantification, etc., depend on the type of the measurement object S. For example, in the case of herbs, cellulose, hemicellulose, lignin, etc. can be mentioned.

[0042] The optical measurement method of the present invention performs near-infrared spectroscopy using the above-described optical measurement device. As shown in Figure 4, with the container 6 set inside the optical measurement jig 1, all or part of the wavelength range from 800 nm to 2500 nm is irradiated. Then, the near-infrared light reflected by the measurement object is detected by the detection unit, and absorbance spectrum data (absorbance by wavelength) is obtained. As the absorbance spectrum data, the original spectrum data may be used, but it is preferable to use the processed original spectrum data. Examples of data processing methods include multiple differentiations such as first derivative and second derivative, smoothing, normalization, combinations of these, etc. Further, multivariate analysis may be performed.

[0043] By applying the previously created calibration model to the obtained absorbance spectrum data of the object to be measured, it is possible to quantify (predict) the content of components contained in the object to be measured. Note that the analysis of spectrum data and the quantification of component content can be performed using, for example, commercially available software or the like.

[0044] Note that the calibration model is created by performing multivariate analysis based on spectrum data for a plurality of specimens of the same type as the object to be measured. As the multivariate analysis, general analysis tools can be used, for example, PLS regression analysis, principal component analysis (PCA), etc. can be used. The above-described optical measurement device may be used during the measurement in creating the calibration model.

[0045] In this way, by using the optical measurement device of the present invention, based on the near-infrared light reflected or transmitted by the object to be measured, the content of the components contained in the object to be measured can be quantified, so that the content of the components can be accurately quantified (predicted).

[0046] FIG. 5 shows a system diagram schematically showing an example of a measurement method using the optical measurement device of the present invention. This system is, for example, a system for quantifying the content of components contained in an object to be measured, and includes an optical measurement device 7, a terminal 8 operated by a user, and a cloud server 9. The optical measurement device 7 and the terminal 8 are communicably connected by wire or wirelessly. Also, the terminal 8 and the cloud server 9 are communicably connected to each other via a network N.

[0047] The terminal 8 is a device operated by a user such as a customer, and is a personal computer, a smartphone, a tablet terminal, or the like. The cloud server 9 exists, for example, on a cloud constructed by a company that performs quantitative analysis, and has a configuration of a general computer, including a control unit, a storage unit, a communication unit, and the like.

[0048] A predetermined application is installed on the terminal 8, and the terminal 8 transmits the absorbance spectrum data acquired from the optical measurement device 7 to the cloud server 9. When the cloud server 9 receives the absorbance spectrum data, a program necessary for the processing is executed, a calibration model for a target component is selected from a plurality of stored calibration models, and the content of the component is calculated based on the selected calibration model. Then, the cloud server 9 transmits data regarding the content of the component to the terminal 8 that is the source of transmission. Thereby, the user can grasp the content of the component contained in the measurement object.

[0049] Note that the present invention is not limited to the configurations described in FIGS. 1 to 5 above, and can be changed as appropriate.

[0050] For example, the sensor body shown in FIG. 3 etc. also has a detection unit and is configured to detect near-infrared light reflected by the measurement object, but a detection unit may be provided separately from the sensor body to detect near-infrared light transmitted through the measurement object. In this case, the detection unit is provided, for example, inside the lid member (at a position facing the container).

Example

[0051] In order to verify the effects when using the optical measurement jig of the present invention, the following experiment was conducted.

[0052] The coarsely pulverized herb was used as a sample for the calibration model, and measurement was performed by near-infrared spectroscopy, and calibration models for each component (cellulose, hemicellulose, lignin) contained therein were created respectively.

[0053] [Example 1 (with jig)] As the object to be measured, coarsely pulverized herbs 1 to 3 (different from the samples for the calibration model) were used. Each herb was filled in a glass petri dish, and the petri dish was placed on the placement surface as shown in Fig. 6. Then, the petri dish was covered with a lid member so as to cover the entire petri dish. A commercially available near-infrared analyzer was used as the sensor body, and measurements were performed in the range of 800 nm to 2500 nm to obtain absorbance spectrum data. The obtained absorbance spectrum data was applied to a previously created cellulose calibration model, hemicellulose calibration model, and lignin calibration model, respectively, to quantify the contents of each component (cellulose, hemicellulose, lignin). For herbs 1 to 3, measurements were performed five times each, and the respective contents (mass %) and relative standard deviations (%) were calculated. The results are shown in Table 1.

[0054] [Comparative Example 1 (without jig)] An experiment was conducted in the same manner as in Example 1 above, except that an optical measurement jig was not used. As shown in Fig. 7, the measurement method was to place the petri dish on the irradiation part of the sensor body and measure it in an open system while holding it by hand. The results are also shown in Table 1.

[0055] [Table 1]

[0056] As shown in Table 1, in all cases of herbs 1 to 3, the variation in the content was smaller when there was a "jig" compared to when there was "no jig". In particular, for hemicellulose, there was a tendency for it to be more variable without a jig, but this could be suppressed by using a jig. [Industrial Applicability]

[0057] The optical measurement jig and optical measurement device of the present invention can be measured simply and accurately in near-infrared spectroscopy, so anyone can perform it with good reproducibility, and it can be widely used in near-infrared spectroscopy. [Explanation of Reference Numerals]

[0058] 1 Optical measurement jig 2 pedestal members 21 notch 22 placement surface 23 recess 24 peripheral wall 25 through-hole 3 cover member 4 spacer member 41 through-hole 42 locking portion 5 sensor body 51 irradiation portion 6 container 7 optical measurement device 8 terminal 9 cloud server S object to be measured

Claims

1. An optical measurement jig used in near-infrared spectroscopy for detecting near-infrared light reflected or transmitted by a measurement object, using a sensor body having an irradiation unit that irradiates the measurement object filled in a container with near-infrared light, wherein the optical measurement jig includes a pedestal member having a placement surface on which the container is horizontally placed and a recess provided recessed from the placement surface and having the sensor body mounted thereon with the irradiation unit facing upward, and a lid member that covers the placement surface together with the container.

2. The optical measurement jig according to claim 1, wherein in the pedestal member, the recess is formed such that the position of the irradiation unit of the sensor body is eccentric from the center position of the container in a plan view.

3. The optical measurement jig further includes a flat spacer member in which a through-hole into which the container can be fitted is formed, and the spacer member is placed on the placement surface together with the container and restricts the movement of the container placed in the through-hole. The optical measurement jig according to claim 1 or claim 2.

4. The optical measurement jig according to claim 3, wherein the spacer member is a black member.

5. The pedestal member has a notch in a part of its outer peripheral surface, and the spacer member has a locking portion that locks to the notch. The optical measurement jig according to claim 3.

6. An optical measurement device including a sensor body having an irradiation unit that irradiates a measurement object filled in a container with near-infrared light, and detecting near-infrared light reflected or transmitted by the measurement object, wherein the optical measurement device includes a pedestal member having a placement surface on which the container is horizontally placed and a recess provided recessed from the placement surface and having the sensor body mounted thereon with the irradiation unit facing upward, and a lid member that covers the placement surface together with the container.

7. An optical measurement method for performing near-infrared spectroscopy using the optical measurement device according to claim 6, characterized by quantifying the content of components contained in the measurement object based on the near-infrared light reflected or transmitted by the measurement object.

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