Spectroscopic measurement device

Abstract

This spectroscopic measurement device comprises: a first light source that emits first irradiation light at a first half-value angle with a first optical axis as the center line; a second light source that emits second irradiation light at a second half-value angle with a second optical axis as the center line; and a detection unit that has a field of view with a third optical axis as the center line, and disperses and detects measurement light produced from an object. The first light source and the second light source are positioned relative to the detection unit in a plane that is perpendicular to the third optical axis, such that the distance between the first optical axis and the third optical axis and the distance between the second optical axis and the third optical axis are equal to each other. The absolute value of the difference between the first half-value angle and the second half-value angle is 4 degrees or less.

Description

Spectroscopic measurement equipment

[0001] The present disclosure relates to a spectroscopic measurement device.

[0002] A spectroscopic measurement device is known that includes a first light source that emits irradiation light having a first central wavelength, a second light source that emits irradiation light having a second central wavelength different from the first central wavelength, and a detection unit that disperses and detects measurement light emitted from an object in response to irradiation with the irradiation light (see, for example, Patent Document 1). Such a spectroscopic measurement device is used to obtain a predetermined quantitative value of the object (for example, fat mass in the human body) by utilizing the property that the object (for example, fat contained in the human body) easily absorbs light of a specific wavelength.

[0003] Japanese Patent Application Laid-Open No. 2019-070550

[0004] In a spectroscopic measurement device such as that described above, in order to accurately obtain a specified quantitative value of an object, it is ideal that the outline of the spectroscopic spectrum of the measurement light does not change. However, if the distance between the object and the spectroscopic measurement device changes, in some cases the outline of the spectroscopic spectrum of the measurement light may change significantly, resulting in a deterioration in measurement accuracy.

[0005] An object of the present disclosure is to provide a spectroscopic measurement device that can suppress deterioration in measurement accuracy even when the distance between an object and the spectroscopic measurement device changes.

[0006] A spectroscopic measurement device according to one aspect of the present disclosure is [1] "a spectroscopic measurement device including: a first light source that emits first irradiation light having a first central wavelength at a first half-value angle around a first optical axis as a center line; a second light source that emits second irradiation light having a second central wavelength different from the first central wavelength at a second half-value angle around the second optical axis as a center line; and a detection unit that has a field of view with a third optical axis as a center line and that separates and detects measurement light emitted from an object in response to irradiation with the first irradiation light and the second irradiation light, wherein the first light source and the second light source are arranged on a plane perpendicular to the third optical axis with respect to the detection unit so that a distance between the first optical axis and the third optical axis and a distance between the second optical axis and the third optical axis are equal to each other, and an absolute value of a difference between the first half-value angle and the second half-value angle is 4 degrees or less."

[0007] In the spectroscopic measurement device described in [1] above, the first light source and the second light source are arranged on a plane perpendicular to the third optical axis relative to the detection unit so that the distance between the first optical axis of the first light source and the third optical axis of the detection unit is equal to the distance between the second optical axis of the second light source and the third optical axis of the detection unit. The absolute value of the difference between the first half-value angle of the first irradiation light and the second half-value angle of the second irradiation light is 4 degrees or less. This prevents a significant change in the ratio of the light intensity of the first irradiation light to the light intensity of the second irradiation light in the field of view of the detection unit, with the third optical axis as its center line, even if the distance between the object and the spectroscopic measurement device changes. Therefore, the spectroscopic spectrum of the measurement light, whose outline should ideally not change even if the distance between the object and the spectroscopic measurement device changes, is prevented from changing significantly. Therefore, the spectroscopic measurement device described in [1] above can prevent a deterioration in measurement accuracy even if the distance between the object and the spectroscopic measurement device changes.

[0008] The spectroscopic measurement device according to one aspect of the present disclosure may be [2] "the spectroscopic measurement device according to the above [1], wherein the detection unit includes a lens that defines the field of view so that the spread angle of the field of view is between -5 degrees and 5 degrees, a light guide unit that guides the measurement light that has passed through the lens, and a spectroscope that disperses and detects the measurement light guided by the light guide unit." According to the spectroscopic measurement device according to [2], the measurement range can be made approximately constant regardless of the distance between the object and the spectroscopic measurement device.

[0009] A spectroscopic measurement device according to one aspect of the present disclosure may be the spectroscopic measurement device according to [3] above, wherein "the first light source is each of a plurality of first light sources, the second light source is each of a plurality of second light sources, and the plurality of first light sources and the plurality of second light sources are alternately arranged on a circumference centered at an intersection of the third optical axis and the plane." According to the spectroscopic measurement device according to [3], it is possible to uniformly irradiate the first irradiation light and the second irradiation light onto an object positioned on the third optical axis. This makes it possible to maintain a constant ratio between the intensity of the first irradiation light and the intensity of the second irradiation light on the object even at positions shifted from the third optical axis. As a result, it is possible to further suppress deterioration in the measurement accuracy of a predetermined quantitative value of the object.

[0010] The spectroscopic measurement device according to one aspect of the present disclosure may be the spectroscopic measurement device according to any one of [1] to [3] above, wherein [4] "the first light source includes a first light-emitting element that emits the first irradiation light, a first reflector that reflects the first irradiation light emitted from the first light-emitting element, and a first sealing member that seals the first light-emitting element and the first reflector, and the second light source includes a second light-emitting element that emits the second irradiation light, a second reflector that reflects the second irradiation light emitted from the second light-emitting element, and a second sealing member that seals the second light-emitting element and the second reflector." According to the spectroscopic measurement device according to [4], the first light source and the second light source can each be disposed at a desired position relative to a detection unit.

[0011] The spectroscopic measurement device according to one aspect of the present disclosure may be the spectroscopic measurement device described in [4] above, [5] "wherein the first light source further includes a first lens detachable from the first sealing member, and the second light source further includes a second lens detachable from the second sealing member, the first lens transmitting the first irradiation light reflected by the first reflector and transmitted through the first sealing member, thereby emitting the first irradiation light at the first half-value angle with the first optical axis as a center line, and the second lens transmitting the second irradiation light reflected by the second reflector and transmitted through the second sealing member, thereby emitting the second irradiation light at the second half-value angle with the second optical axis as a center line." According to the spectroscopic measurement device described in [5], by performing at least one of replacing the first lens with respect to the first sealing member and replacing the second lens with respect to the second sealing member, each of the first half-value angle and the second half-value angle can be easily adjusted to a desired half-value angle.

[0012] The spectroscopic measurement device according to one aspect of the present disclosure may be the spectroscopic measurement device according to any one of [1] to [3] above, wherein the first light source includes a first light-emitting element that emits the first irradiation light, the second light source includes a second light-emitting element that emits the second irradiation light, and the first light source and the second light source share a reflector that reflects the first irradiation light emitted from the first light-emitting element and the second irradiation light emitted from the second light-emitting element, and a sealing member that seals the first light-emitting element, the second light-emitting element, and the reflector. The spectroscopic measurement device according to [6] can easily achieve a configuration in which the absolute value of the difference between the first half-value angle and the second half-value angle is 4 degrees or less.

[0013] The spectroscopic measurement device according to one aspect of the present disclosure may be [7] "the spectroscopic measurement device according to any one of [1] to [6] above, wherein the first central wavelength and the second central wavelength are within the range of 360 nm to 2500 nm." The spectroscopic measurement device according to [7] can appropriately acquire a spectroscopic spectrum required to measure a predetermined quantitative value of an object.

[0014] The spectroscopic measurement device according to one aspect of the present disclosure may be [8] "the spectroscopic measurement device according to any one of the above [1] to [7], further comprising a calculation unit that calculates a predetermined quantitative value of the object based on the detection signal output from the detection unit." The spectroscopic measurement device according to [8] can appropriately obtain the predetermined quantitative value of the object.

[0015] The spectroscopic measurement device according to one aspect of the present disclosure may be [9] "the spectroscopic measurement device according to any one of [1] to [8] above, in which at least one of the first half-value angle and the second half-value angle is equal to or greater than 20 degrees." According to the spectroscopic measurement device according to [9], the absolute value of the difference between the first half-value angle and the second half-value angle becomes relatively small for each of the first half-value angle of the first irradiation light and the second half-value angle of the second irradiation light, and therefore the influence of the difference between the first half-value angle and the second half-value angle on measurement accuracy can be more reliably reduced.

[0016] According to the present disclosure, it is possible to provide a spectroscopic measurement device that can suppress deterioration in measurement accuracy even when the distance between the object and the spectroscopic measurement device changes.

[0017] FIG. 1 is a diagram illustrating an example of use of a spectroscopic measurement device according to an embodiment. FIG. 2 is a cross-sectional view of the spectroscopic measurement device illustrated in FIG. 1. FIG. 3 is a cross-sectional view of the spectroscopic measurement device taken along line III-III illustrated in FIG. 2. FIG. 4 is a side view of a first light source and a second light source illustrated in FIG. 2. FIG. 5 is a diagram for explaining a half-value angle. FIG. 6 is a diagram illustrating a positional relationship between an irradiation range of the first irradiation light, an irradiation range of the second irradiation light, and a field of view of a detection unit in the spectroscopic measurement device illustrated in FIG. 1. FIG. 7 is a diagram illustrating a positional relationship between an irradiation range of the first irradiation light, an irradiation range of the second irradiation light, and a field of view of a detection unit in a spectroscopic measurement device of a comparative example. FIG. 8 is a diagram illustrating a spectral spectrum of measurement light in the spectroscopic measurement device illustrated in FIG. 1 and a spectral spectrum of measurement light in a spectroscopic measurement device of a comparative example. FIG. 9 is a side view of a first light source and a second light source according to a modified example. FIG. 10 is a side view of a first light source and a second light source according to a modified example. FIG. 11 is a diagram illustrating an example of use of the spectroscopic measurement device according to the modified example.

[0018] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings. In the following description, the same or equivalent elements will be designated by the same reference numerals, and redundant description will be omitted. [Configuration of spectroscopic measurement device]

[0019] 1, the spectroscopic measurement device 1 irradiates an object S with two types of irradiation light L11 and L12, and calculates a predetermined quantitative value of the object S by detecting and dispersing the measurement light L2 emitted from the object S in response to the irradiation of the two types of irradiation light L11 and L12. The spectroscopic measurement device 1 acquires the predetermined quantitative value of the object S by utilizing the property of the measurement object that the object easily absorbs light of a specific wavelength. In the example shown in FIG. 1, the spectroscopic measurement device 1 is disposed above a conveyor C, and acquires a predetermined quantitative value (e.g., sugar content, moisture content, etc. contained in fruit) of the object S (e.g., fruit) transported by the conveyor C.

[0020] As shown in Figures 2 and 3, the spectroscopic measurement device 1 includes a housing 2, a support unit 3, a plurality of first light sources 4, a plurality of second light sources 5, a detection unit 6, and a calculation unit 7.

[0021] The housing 2 accommodates the support unit 3, the plurality of first light sources 4, the plurality of second light sources 5, the detection unit 6, and the calculation unit 7. The housing 2 includes a cylindrical main body 21 and a plate-shaped light-transmitting unit 22. The main body 21 has a center line parallel to direction A. The light-transmitting unit 22 closes one end of the main body 21 with the thickness direction of the light-transmitting unit 22 coinciding with direction A.

[0022] The support portion 3 includes a support structure 31, a wiring board 32, and a holding member 33. The support structure 31 is fixed to the main body portion 21 within the main body portion 21. The wiring board 32 is arranged on one side of the support structure 31 in the direction A, with the thickness direction of the wiring board 32 coinciding with the direction A. The wiring board 32 has openings 32a that open to one and the other sides in the direction A. The holding member 33 is arranged on one side of the wiring board 32 in the direction A. The wiring board 32 is fixed to the holding member 33 with bolts 34. The holding member 33 has a plurality of through holes 33a and one through hole 33b. Each of the through holes 33a and 33b penetrates the holding member 33 along the direction A.

[0023] The first light sources 4 and the second light sources 5 are mounted on a mounting surface 32b of the wiring board 32 while being positioned within the through holes 33a of the holding member 33. The mounting surface 32b is one of a pair of main surfaces of the wiring board 32 in the direction A. Each first light source 4 has a first optical axis A1 parallel to the direction A and emits a first irradiation light L11 toward one side in the direction A. Each second light source 5 has a second optical axis A2 parallel to the direction A and emits a second irradiation light L12 toward one side in the direction A. The first irradiation light L11 is light having a first central wavelength. The second irradiation light L12 is light having a second central wavelength different from the first central wavelength.

[0024] The detection unit 6 is fixed to the support unit 3 while being positioned within the opening 32a of the wiring board 32 and the through-hole 33b of the holding member 33. The detection unit 6 has a field of view V whose center line is a third optical axis A3 parallel to the direction A, and detects the measurement light L2 by separating the measurement light L2. The measurement light L2 is light emitted from the object S in response to irradiation with the first irradiation light L11 and the second irradiation light L12.

[0025] The detection unit 6 includes a lens 61, a light guiding unit 62, and a spectroscope 63. The lens 61 is disposed on one side of the light guiding unit 62 in the direction A on the third optical axis A3. The spectroscope 63 is disposed on the other side of the light guiding unit 62 in the direction A on the third optical axis A3.

[0026] The lens 61 is fixed to the inner surface 22a of the light transmitting portion 22 while being positioned within the through-hole 33b of the holding member 33. The lens 61 defines the field of view V so that the spread angle of the field of view V is between -5 degrees and 5 degrees. In this embodiment, the spread angle of the field of view V is 0 degrees. In this case, the range of the field of view V is, for example, a cylindrical range with the third optical axis A3 as the center line.

[0027] A field of view V with a spread angle of N degrees (N is a positive value) is a frustum-shaped field of view whose range widens the further away from the lens 61, and the taper angle of the frustum is N degrees. A field of view V with a spread angle of 0 degrees means a field of view whose range remains constant even when the distance is farther from the lens 61. A field of view V with a spread angle of -N degrees is a frustum-shaped field of view whose range narrows the further away from the lens 61, and the taper angle of the frustum is N degrees.

[0028] The light guide 62 guides the measurement light L2 transmitted through the lens 61 from one side to the other side in the direction A. The light guide 62 is a cylindrical member with the third optical axis A3 as its center line. The light guide 62 is made of metal (e.g., aluminum). The light guide 62 extends to both sides of the wiring substrate 32 through the opening 32a. The light guide 62 is fixed to the holding member 33 with one side of the light guide 62 positioned inside the through-hole 33b. The light entrance opening 62a of the light guide 62 is located on one side of the wiring substrate 32, and the light exit opening 62b of the light guide 62 is located on the other side of the wiring substrate 32. The inner surface 62c of the light guide 62 is a light-reflecting surface.

[0029] The spectroscope 63 disperses and detects the measurement light L2 guided by the light guide 62. The spectroscope 63 includes a housing having a light incident portion 63a onto which the measurement light L2 is incident, a diffraction grating that disperses the incident measurement light L2 within the housing, and a photodetector that detects the dispersed measurement light L2 within the housing. The housing of the spectroscope 63 is fixed to the support structure 31.

[0030] The calculation unit 7 is fixed to the support structure 31. Each of the first light sources 4 and each of the second light sources 5 are electrically connected to the calculation unit 7 via a wiring board 32. The light detection elements of the spectroscope 63 are electrically connected to the calculation unit 7 via wiring 8. The calculation unit 7 is configured by electronic components including, for example, an integrated circuit such as an FPGA (field-programmable gate array) and a non-volatile memory such as an EEPROM (electrically erasable programmable read-only memory).

[0031] The calculation unit 7 calculates a predetermined quantitative value of the object S based on the detection signal output from the detection unit 6. Specifically, the calculation unit 7 performs spectroscopic measurement on the object S transported below the spectroscopic measurement device 1 by the conveyor C. The calculation unit 7 generates first data indicating the spectral spectrum of the measurement light L2 based on the detection signal output from the detection unit 6. The calculation unit 7 generates second data indicating a second-order derivative spectrum obtained by second-order differentiation of the spectral spectrum of the measurement light L2 based on the first data. The calculation unit 7 calculates a predetermined quantitative value of the object S based on the second data. In this embodiment, the calculation unit 7 also functions as a control unit that controls the multiple first light sources 4, the multiple second light sources 5, and the detection unit 6. The calculation unit 7 as a control unit causes the multiple first light sources 4 and the multiple second light sources 5 to simultaneously emit the first irradiation light L11 and the second irradiation light L12, while causing the detection unit 6 (specifically, the photodetector element of the spectroscope 63) to detect the measurement light L2. [Positions of the First Light Source and the Second Light Source Relative to the Detection Unit]

[0032] The first light sources 4 and the second light sources 5 are arranged on a plane H perpendicular to the third optical axis A3 so that the distance between each first optical axis A1 and the third optical axis A3 and the distance between each second optical axis A2 and the third optical axis A3 are equal to each other with respect to the detection unit 6. In this embodiment, the plane H is a plane including the mounting surface 32b of the wiring board 32. The first light sources 4 and the second light sources 5 are arranged alternately on a circumference R centered on an intersection C1 between the third optical axis A3 and the plane H. In this embodiment, the first light sources 4 and the second light sources 5 are arranged at equal angular intervals around the intersection C1. In other words, the first light sources 4 and the second light sources 5 are arranged rotationally symmetrically around the intersection C1. As an example, the first light sources 4 and the second light sources 5 are arranged point-symmetrically (two-fold symmetrically) around the intersection C1. [Configuration of First Light Source and Second Light Source]

[0033] As shown in FIG. 4A , the first light source 4 is a first LED 40. In this embodiment, the first LED 40 is a bullet-shaped LED (light emitting diode). The first LED 40 includes a first light-emitting element 41, a first reflector 42, and a first sealing member 43. The first light-emitting element 41 emits a first irradiation light L11. The first reflector 42 has a reflecting surface 42a facing the first light-emitting element 41 on the other side in the direction A (the lower side in FIG. 4A ). The reflecting surface 42a reflects the first irradiation light L11 emitted from the first light-emitting element 41 to one side in the direction A (the upper side in FIG. 4A ). The first sealing member 43 seals the first light-emitting element 41 and the first reflector 42. The first irradiation light L11 is reflected by the first reflecting plate 42 and passes through the first sealing member 43, and is emitted from the first light source 4 at a first half-value angle θ1 with the first optical axis A1 as the center line.

[0034] As shown in FIG. 4B , the second light source 5 is a second LED 50. In this embodiment, the second LED 50 is a bullet-shaped LED. The second LED 50 includes a second light-emitting element 51, a second reflector 52, and a second sealing member 53. The second light-emitting element 51 emits second irradiation light L12. The second reflector 52 has a reflective surface 52a facing the second light-emitting element 51 on the other side in the direction A. The reflective surface 52a reflects the second irradiation light L12 emitted from the second light-emitting element 51 to one side in the direction A. The second sealing member 53 seals the second light-emitting element 51 and the second reflector 52. The second irradiation light L12 is reflected by the second reflector 52 and passes through the second sealing member 53, and is emitted from the second light source 5 at a second half-value angle θ2 with the second optical axis A2 as the center line.

[0035] At least one of the first half-value angle θ1 and the second half-value angle θ2 is 20 degrees or greater. The absolute value of the difference between the first half-value angle θ1 and the second half-value angle θ2 is 4 degrees or less. As shown in Fig. 5, the "half-value angle θ" is a value expressed as 2α, where α is the angle at which the intensity of the irradiated light is half of the intensity of the irradiated light on the optical axis, with the optical axis as the center (0 degrees).

[0036] The first central wavelength and the second central wavelength are within the range of 360 nm to 2500 nm. The first central wavelength and the second central wavelength are determined according to the absorption wavelength of the object to be measured. Specifically, the first central wavelength and the second central wavelength are determined to be values ​​close to the absorption wavelength of the object to be measured. As an example, the absorption wavelength of fat is 930 nm, the absorption wavelength of water is 956 nm, and the absorption wavelength of chlorophyll is 670 nm. The first central wavelength and the second central wavelength may be within the visible range of 360 nm to 830 nm, or may be within the near-infrared range of 780 nm to 2500 nm. [Changes in the spectral spectrum of the measurement light depending on the distance between the object and the spectroscopic measurement device]

[0037] Changes in the general shape of the spectrum of the measurement light L2 depending on the distance between the object S and the spectroscopic measurement device 1 will be described with reference to FIGS. 6, 7, and 8. FIG. 6 illustrates the positional relationship between the irradiation range of the first irradiation light L11, the irradiation range of the second irradiation light L12, and the field of view V of the detection unit 6 in the spectroscopic measurement device 1 shown in FIG. 1. FIG. 7 illustrates the positional relationship between the irradiation range of the first irradiation light L11, the irradiation range of the third irradiation light L13, and the field of view V of the detection unit 6 in a spectroscopic measurement device 101 in a comparative example. (a) of FIG. 8 illustrates the spectrums G21, G22, and G23 of the measurement light L21, L22, and L23 emitted from the object S at positions P1, P2, and P3 in FIG. 6. (b) of FIG. 8 illustrates the spectrums G121, G122, and G123 of the measurement light L121, L122, and L123 emitted from the object S at positions P1, P2, and P3 in FIG. 7. 6, the arrangement of the first light source 4, the second light source 5, and the detection unit 6 is simplified, and the detection unit 6 is disposed at the midpoint between one first light source 4 and one second light source 5. Similarly, in FIG. 7, the detection unit 6 is disposed at the midpoint between one first light source 4 and one third light source 500.

[0038] As shown in FIG. 6 , in the spectroscopic measurement device 1 of this embodiment, the ratio of the light intensity of the first irradiation light L11 to the light intensity of the second irradiation light L12 in the field of view V is approximately constant regardless of whether the object S is positioned at any of the three positions P1, P2, or P3. Therefore, as shown in FIG. 8A , the ratio of the intensity at the second central wavelength λ2 to the intensity at the first central wavelength λ1 in each of the spectral spectra G21, G22, and G23 of the measurement light L2 is approximately constant. In other words, the overall shape of the spectral spectrum of the measurement light L2 does not change significantly. This results in the waveforms of the second-order derivative spectra of the three spectral spectra G21, G22, and G23 being approximately constant. As a result, the quantitative values ​​calculated by the calculation unit 7 are constant regardless of whether the object S is positioned at any of the three positions P1, P2, or P3.

[0039] As shown in FIG. 7 , the spectroscopic measurement device 101 of the comparative example includes a third light source 500 instead of the second light source 5. The third light source 500 has a configuration similar to that of the second light source 5, except that it has a third half-value angle θ3 that is different from the second half-value angle θ2 of the second light source 5. The third half-value angle θ3 is larger than the first half-value angle θ1. The absolute value of the difference between the first half-value angle θ1 and the third half-value angle θ3 is greater than 4 degrees, e.g., 30 degrees. In the comparative example, as shown in FIG. 7 , as the object S moves from position P1 to positions P2 and P3 and becomes farther away from the detection unit 6, the ratio of the light intensity of the first irradiation light L11 to the light intensity of the third irradiation light L13 changes significantly in the field of view V. Therefore, as shown in FIG. 8B , the ratio of the intensity at the second central wavelength λ2 to the intensity at the first central wavelength λ1 changes significantly in each of the spectral spectra G121, G122, and G123 of the measurement light L2. In other words, the general shape of the spectrum of the measurement light L2 changes significantly. As a result, the waveforms of the second derivative spectra of the three spectrums G121, G122, and G123 differ from one another. As a result, the quantitative value calculated by the calculation unit 7 changes depending on which of the three positions P1, P2, or P3 the target object S is placed at. [Function and Effect]

[0040] In the spectroscopic measurement device 1, the first light source 4 and the second light source 5 are arranged on a plane H perpendicular to the third optical axis A3 with respect to the detection unit 6 so that the distance between the first optical axis A1 of the first light source 4 and the third optical axis A3 of the detection unit 6 is equal to the distance between the second optical axis A2 of the second light source 5 and the third optical axis A3 of the detection unit 6. The absolute value of the difference between the first half-value angle θ1 of the first irradiation light L11 and the second half-value angle θ2 of the second irradiation light L12 is 4 degrees or less. This prevents a significant change in the ratio of the light intensity of the first irradiation light L11 to the light intensity of the second irradiation light L12 in the field of view V of the detection unit 6, with the third optical axis A3 as its center line, even if the distance between the object S and the spectroscopic measurement device 1 changes. Therefore, even if the distance between the object S and the spectroscopic measurement device 1 changes, the spectral shape of the measurement light L2, the spectral shape of which should ideally not change, is prevented from changing significantly. This makes it possible to suppress deterioration of measurement accuracy even if the distance between the object S and the spectroscopic measurement device 1 changes.

[0041] In the spectroscopic measurement device 1, the lens 61 defines the field of view V of the detection unit 6 so that the spread angle of the field of view V is between −5 degrees and 5 degrees. This makes it possible to keep the measurement range approximately constant regardless of the distance between the object S and the spectroscopic measurement device 1.

[0042] In the spectroscopic measurement device 1, the multiple first light sources 4 and the multiple second light sources 5 are alternately arranged on a circumference R centered at the intersection C1 of the third optical axis A3 and the plane H. Therefore, it is possible to uniformly irradiate the first irradiation light L11 and the second irradiation light L12 onto the object S located on the third optical axis A3. This makes it possible to keep the ratio between the intensity of the first irradiation light L11 and the intensity of the second irradiation light L12 constant on the object S even at positions shifted from the third optical axis A3. As a result, it is possible to further suppress deterioration in the measurement accuracy of a predetermined quantitative value of the object S.

[0043] In the spectroscopic measurement device 1, the multiple first light sources 4 and the multiple second light sources 5 are arranged to be rotationally symmetric with respect to the intersection C1 between the third optical axis A3 and the plane H. For example, the multiple first light sources 4 and the multiple second light sources 5 are arranged to be point-symmetric with respect to the intersection C1 between the third optical axis A3 and the plane H. This makes it possible to uniformly irradiate the first irradiation light L11 and the second irradiation light L12 onto the object S located on the third optical axis A3, even when the spectroscopic measurement device 1 rotates around the third optical axis A3.

[0044] In the spectroscopic measurement device 1, the first sealing member 43 seals the first light-emitting element 41 and the first reflector 42, and the second sealing member 53 seals the second light-emitting element 51 and the second reflector 52. This allows the first light source 4 and the second light source 5 to be disposed at desired positions relative to the detection unit 6.

[0045] In the spectroscopic measurement device 1, the first central wavelength and the second central wavelength are within the range of 360 nm to 2500 nm, so that the spectroscopic spectrum required to measure a predetermined quantitative value of the object S can be appropriately acquired.

[0046] In the spectroscopic measurement device 1, the calculation unit 7 calculates a predetermined quantitative value of the object S based on the detection signal output from the detection unit 6. This makes it possible to appropriately acquire the predetermined quantitative value of the object S.

[0047] In the spectroscopic measurement device 1, at least one of the first half-value angle θ1 and the second half-value angle θ2 is equal to or greater than 20 degrees. This makes the absolute value of the difference between the first half-value angle θ1 and the second half-value angle θ2 relatively small for each of the first half-value angle θ1 of the first irradiation light L11 and the second half-value angle θ2 of the second irradiation light L12, thereby more reliably reducing the effect on measurement accuracy due to the difference between the first half-value angle θ1 and the second half-value angle θ2. [Modification]

[0048] The present disclosure is not limited to the above-described embodiment. In the spectroscopic measurement device 1 of the first modified example, as shown in FIGS. 9A and 9B , the first light source 4 may further include a first lens 46 that is detachable from the first sealing member 43. The second light source 5 may further include a second lens 56 that is detachable from the second sealing member 53. The first lens 46 may transmit the first irradiation light L11 that has been reflected by the first reflecting plate 42 and transmitted through the first sealing member 43, thereby emitting the first irradiation light L11 at a first half-value angle θ1 around the first optical axis A1 as a center line. The second lens 56 may transmit the second irradiation light L12 that has been reflected by the second reflecting plate 52 and transmitted through the second sealing member 53, thereby emitting the second irradiation light L12 at a second half-value angle θ2 around the second optical axis A2 as a center line. In the spectroscopic measurement device 1 of the first modified example, by replacing the first lens 46 with respect to the first sealing member 43 or by replacing the second lens 56 with respect to the second sealing member 53, the first half-value angle θ1 and the second half-value angle θ2 can each be easily adjusted to the desired half-value angle.

[0049] In the spectroscopic measurement device 1 of the second modified example, the first light source 4 includes a first reflector 42 and a first sealing member 43, and the second light source 5 includes a second reflector 52 and a second sealing member 53. However, this is not limited to this. For example, as shown in FIG. 10 , the first light source 4 and the second light source 5 may share a reflector 142 and a sealing member 143. The sealing member 143 seals the first light-emitting element 41, the second light-emitting element 51, and the reflector 142. The reflector 142 has a reflecting surface 142a that faces the first light-emitting element 41 and the second light-emitting element 51 on the other side in the direction A (the lower side in FIG. 10 ). The reflector 142 reflects the first irradiation light L11 emitted from the first light-emitting element 41 and the second irradiation light L12 emitted from the second light-emitting element 51 to one side in the direction A (the upper side in FIG. 10 ). In the spectroscopic measurement device 1 of the second modified example, it is possible to easily realize a configuration in which the absolute value of the difference between the first half-value angle θ1 and the second half-value angle θ2 is 4 degrees or less.

[0050] In the above embodiment and each modified example, the plane H is a plane that includes the mounting surface 32b of the wiring board 32, but this is not limited to this. The plane may be any plane that is perpendicular to the third optical axis A3. For example, the plane may be a plane that includes a surface other than the mounting surface 32b of the wiring board 32, or may be a plane that does not include any surface.

[0051] In the above embodiment and each modified example, the detection unit 6 only needs to spectrally detect the measurement light L2. For example, the detection unit 6 only needs to have at least the spectroscope 63. As an example, the detection unit 6 does not need to have the lens 61. In this case, the field of view V may be defined so that the spread angle of the field of view V is greater than -5 degrees or less than 5 degrees. Furthermore, for example, the detection unit 6 may be another optical sensor capable of spectrally detecting the measurement light L2.

[0052] In the above embodiment and each modified example, the multiple first light sources 4 and the multiple second light sources 5 are alternately arranged on the circumference R centered at the intersection C1 of the plane H perpendicular to the third optical axis A3 and the third optical axis A3, but this is not limited to this. The multiple first light sources 4 and the multiple second light sources 5 may be arranged on the plane H perpendicular to the third optical axis A3 so that the distance between the first optical axis A1 of the first light source 4 and the third optical axis A3 of the detection unit 6 and the distance between the second optical axis A2 of the second light source 5 and the third optical axis A3 of the detection unit 6 are equal to each other, with respect to the detection unit 6. For example, the multiple first light sources 4 may be adjacent to each other on the circumference R, and the multiple second light sources 5 may be adjacent to each other on the circumference R.

[0053] In the above embodiment and each modified example, the first light source 4 includes the first LED 40, and the second light source 5 includes the second LED 50. However, this is not limiting. The first light source 4 and the second light source 5 may include light-emitting elements other than LEDs.

[0054] In the above embodiment and each modified example, a plurality of first light sources 4 and a plurality of second light sources 5 are provided, but it is sufficient that at least one first light source 4 and at least one second light source 5 are provided.

[0055] In the above embodiment and each modified example, the first central wavelength and the second central wavelength are in the range of 360 nm to 2500 nm, but are not limited thereto. At least one of the first central wavelength and the second central wavelength may be shorter than 360 nm or longer than 2500 nm.

[0056] In the above embodiment and each modified example, the spectroscopic measurement device 1 does not need to include the calculation unit 7. For example, a calculation device provided outside the spectroscopic measurement device 1 may calculate a predetermined quantitative value of the target object S based on the detection signal output from the detection unit 6. Examples of the calculation device include a computer device such as a personal computer, a smartphone, or a tablet terminal.

[0057] In the above embodiment and each modified example, at least one of the first half-value angle θ1 and the second half-value angle θ2 is 20 degrees or more, but this is not limiting. For example, both the first half-value angle θ1 and the second half-value angle θ2 may be less than 20 degrees.

[0058] In the above embodiment and each modified example, the spectroscopic measurement device 1 is disposed above the conveyor C, and measurement is performed when the object S is transported below the spectroscopic measurement device 1 by the conveyor C. However, this is not limited to this. For example, the user U may manually move the spectroscopic measurement device 1 above the object S and perform measurement when the user U presses a switch. Furthermore, for example, as shown in FIG. 11 , the spectroscopic measurement device 1 may be provided below a drone D. In this case, when the drone D reaches above the object S due to an operation by the user U, the spectroscopic measurement device 1 may automatically perform measurement.

[0059] 1...spectroscopic measurement device, 4...first light source, 5...second light source, 6...detection unit, 7...calculation unit, 41...first light-emitting element, 42...first reflector, 43...first sealing member, 46...first lens, 51...second light-emitting element, 52...second reflector, 53...second sealing member, 56...second lens, 61...lens, 62...light-guiding unit, 63...spectroscope, 142...reflector, 143...sealing member, A1...first optical axis, A2...second optical axis, A3...third optical axis, C1...intersection, L11...first irradiation light, L12...second irradiation light, L2, L21, L22, L23...measurement light, H...plane, R...circumference, S...object, V...field of view, θ1...first half-value angle, θ2...second half-value angle, λ1...first central wavelength, λ2...second central wavelength.

Claims

1. A spectroscopic measurement device comprising: a first light source that emits a first irradiation light having a first central wavelength at a first half-value angle with a first optical axis as a center line; a second light source that emits a second irradiation light having a second central wavelength different from the first central wavelength at a second half-value angle with the second optical axis as a center line; and a detection unit that has a field of view with a third optical axis as a center line and that detects measurement light emitted from an object in response to irradiation with the first irradiation light and the second irradiation light by dispersing the light, wherein the first light source and the second light source are disposed on a plane perpendicular to the third optical axis with respect to the detection unit such that a distance between the first optical axis and the third optical axis and a distance between the second optical axis and the third optical axis are equal to each other; and an absolute value of a difference between the first half-value angle and the second half-value angle is 4 degrees or less.

2. The spectroscopic measurement device of claim 1, wherein the detection unit includes a lens that defines the field of view so that the spread angle of the field of view is between -5 degrees and 5 degrees, a light guiding unit that guides the measurement light that has passed through the lens, and a spectroscope that splits and detects the measurement light guided by the light guiding unit.

3. A spectroscopic measurement device as described in claim 1 or 2, wherein the first light source is each of a plurality of first light sources, the second light source is each of a plurality of second light sources, and the plurality of first light sources and the plurality of second light sources are alternately arranged on a circumference centered on the intersection of the third optical axis and the plane.

4. A spectroscopic measurement device as described in any one of claims 1 to 3, wherein the first light source includes a first light-emitting element that emits the first irradiation light, a first reflector that reflects the first irradiation light emitted from the first light-emitting element, and a first sealing member that seals the first light-emitting element and the first reflector, and the second light source includes a second light-emitting element that emits the second irradiation light, a second reflector that reflects the second irradiation light emitted from the second light-emitting element, and a second sealing member that seals the second light-emitting element and the second reflector.

5. The spectroscopic measurement device described in claim 4, wherein the first light source further includes a first lens detachable from the first sealing member, the second light source further includes a second lens detachable from the second sealing member, the first lens transmits the first irradiation light reflected by the first reflector and transmitted through the first sealing member, and emits the first irradiation light at the first half-value angle with the first optical axis as a center line, and the second lens transmits the second irradiation light reflected by the second reflector and transmitted through the second sealing member, and emits the second irradiation light at the second half-value angle with the second optical axis as a center line.

6. A spectroscopic measurement device according to any one of claims 1 to 3, wherein the first light source includes a first light-emitting element that emits the first irradiation light, the second light source includes a second light-emitting element that emits the second irradiation light, and the first light source and the second light source share a reflector that reflects the first irradiation light emitted from the first light-emitting element and the second irradiation light emitted from the second light-emitting element, and a sealing member that seals the first light-emitting element, the second light-emitting element, and the reflector.

7. A spectroscopic measurement device according to any one of claims 1 to 6, wherein the first central wavelength and the second central wavelength are within the range of 360 nm or more and 2500 nm or less.

8. A spectroscopic measurement device according to any one of claims 1 to 7, further comprising a calculation unit that calculates a predetermined quantitative value of the object based on the detection signal output from the detection unit.

9. A spectroscopic measurement device according to any one of claims 1 to 8, wherein at least one of the first half-value angle and the second half-value angle is 20 degrees or greater.

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