Spectroscopic measurement system

Abstract

This spectroscopic measurement system comprises: a light irradiation unit; a spectroscopic unit; a light detection unit that detects light dispersed by the spectroscopic unit and has sensitivity in a first wavelength region and a second wavelength region shorter than the first wavelength region; and a processing unit. The spectroscopic measurement system includes wavelength switching means capable of switching a detection state between a first state in which first light having a wavelength in the first wavelength region is incident on the spectroscopic unit and N-th order diffracted light of the first light is detected by the light detection unit, and a second state in which second light having a wavelength in the second wavelength region is incident on the spectroscopic unit and M-th order diffracted light of the second light is detected by the light detection unit. Here, N and M are integers other than 0 where the absolute value of N is less than the absolute value of M. The processing unit generates a spectral image on the basis of the N-th order diffracted light and the M-th order diffracted light.

Description

Spectroscopic Measurement System

[0001] One aspect of the present disclosure relates to a spectroscopic measurement system.

[0002] Patent Documents 1 and 2 describe spectroscopic devices that use a diffraction grating to separate incident light and a light detecting section to detect the separated light.

[0003] JP-A No. 57-111422 JP-A No. 8-254464

[0004] Spectroscopic devices such as those described above may be required to have a wider detectable wavelength range. However, it is difficult to make a diffraction grating capable of diffracting light in a wide wavelength range. Even if a diffraction grating capable of diffracting light in a wide wavelength range could be realized, the diffraction efficiency may be low. Furthermore, it is difficult to fabricate a detection element in the light detection unit that can detect a wide wavelength range, and the size of such a detection element tends to be small. This may result in a decrease in dynamic range and wavelength resolution. Furthermore, if the detectable wavelength range is wide, the width (pitch) per unit wavelength in the light detection unit becomes narrow, which may also result in a decrease in dynamic range and wavelength resolution.

[0005] Therefore, one aspect of the present disclosure aims to provide a spectroscopic measurement system that can disperse and detect light in a wide wavelength range with sufficient diffraction efficiency, while ensuring a dynamic range and wavelength resolution.

[0006] a spectroscopic measurement system including: a light irradiation unit that irradiates an object with light; a spectroscopic unit that spectroscopically separates the light from the object irradiated by the light irradiation unit; a light detection unit that detects the light spectroscopically separated by the spectroscopic unit, the light detection unit having sensitivity to a first wavelength range and a second wavelength range shorter than the first wavelength range; and a processing unit; and wavelength switching means that can switch a detection state between a first state in which at least first light having a wavelength in the first wavelength range is incident on the spectroscopic unit and N-th order diffracted light of the first light is detected by the light detection unit, and a second state in which at least second light having a wavelength in the second wavelength range is incident on the spectroscopic unit and M-th order diffracted light of the second light is detected by the light detection unit, wherein N and M are integers other than 0 and the absolute value of N is smaller than the absolute value of M, and the processing unit generates spectroscopic data based on the N-th order diffracted light of the first light detected in the first state and the M-th order diffracted light of the second light detected in the second state.

[0007] In this spectroscopic measurement system, the wavelength switching means can switch the detection state between a first state in which first light having a wavelength in at least a first wavelength range is incident on the spectroscopic unit and N-th order diffracted light of the first light is detected by the photodetector, and a second state in which second light having a wavelength in at least a second wavelength range is incident on the spectroscopic unit and M-th order diffracted light of the second light is detected by the photodetector. Spectroscopic data is generated based on the N-th order diffracted light of the first light detected in the first state and the M-th order diffracted light of the second light detected in the second state. This allows the spectroscopic data to be generated using the N-th order diffracted light of the first light and the M-th order diffracted light of the second light, which have relatively high diffraction efficiencies, thereby enabling light in a wide wavelength range to be dispersed and detected with sufficient diffraction efficiency. Furthermore, in this spectroscopic measurement system, the N-th order diffracted light of the first light is detected by the photodetector in the first state, and the M-th order diffracted light of the second light is detected by the photodetector in the second state. Therefore, for example, the N-th order diffracted light and the M-th order diffracted light can be detected in a common region of the photodetector. As a result, even if the size of the photodetector is small, the width (pitch) per unit wavelength in the photodetector can be prevented from becoming narrow, and the dynamic range and wavelength resolution can be ensured. Therefore, with this spectroscopic measurement system, light in a wide wavelength range can be dispersed and detected with sufficient diffraction efficiency, and the dynamic range and wavelength resolution can be ensured.

[0008] A spectroscopic measurement system according to one aspect of the present disclosure may be the spectroscopic measurement system according to [1], [2] "wherein the wavelength switching means is configured by a filter selection unit that arranges on the optical path a filter selected from a plurality of selective filters including a first filter that transmits the first light and blocks light other than the first light and a second filter that transmits the second light and blocks light other than the second light, and in the first state, the first filter is arranged on the optical path, and in the second state, the second filter is arranged on the optical path." In this case, the wavelength switching means can be configured by a filter selection unit that arranges on the optical path a filter selected from a plurality of selective filters.

[0009] A spectroscopic measurement system according to one aspect of the present disclosure may be the spectroscopic measurement system according to [2], [3] in which "the wavelength switching means is capable of switching the detection state to a third state in which, in addition to the first state and the second state, third light including a first portion having a wavelength in the first wavelength range and a second portion having a wavelength in the second wavelength range is incident on the spectroscopic unit, and N-order diffracted light of the first portion of the third light and M-order diffracted light of the second portion of the third light are detected by the light detection unit, and the processing unit generates the spectroscopic data further based on the N-order diffracted light of the first portion of the third light and the M-order diffracted light of the second portion of the third light detected in the third state." In this case, the spectroscopic data can be generated further based on a detection result of the third light having wavelengths in both the first wavelength range and the second wavelength range.

[0010] A spectroscopic measurement system according to one aspect of the present disclosure may be the spectroscopic measurement system according to [4] or [2], further including a switching unit arranged upstream of the filter selection unit on the optical path, the switching unit having a switching filter that transmits one of the first light and the second light and blocks light other than the one of the first light and the second light, the switching filter being arranged upstream of the filter selection unit on the optical path and capable of switching between a state in which light other than the one of the first light and the second light is blocked and a state in which the switching filter is not arranged upstream of the filter selection unit on the optical path and both the first light and the second light are incident on the filter selection unit. In this case, for example, even if the characteristics of multiple selection filters are not stored in advance, by performing a predetermined process, it is possible to determine whether light detected by a light detection unit using a certain selection filter is N-order diffracted light of the first light or M-order diffracted light of the second light. For example, for each selection filter, detection results are obtained both in a state in which a switching filter is arranged and in a state in which a switching filter is not arranged. The above determination is made by using these detection results.

[0011] A spectroscopic measurement system according to one aspect of the present disclosure may be [5] "the spectroscopic measurement system according to [1], wherein the light irradiating unit is configured to vary the wavelength of light irradiated onto the object, the wavelength switching means is configured by the light irradiating unit, and the detection state is switched between the first state and the second state by changing the wavelength of light irradiated onto the object from the light irradiating unit." In this case, the wavelength switching means can be configured by a light irradiating unit configured to vary the wavelength of light irradiated onto the object.

[0012] A spectroscopic measurement system according to one aspect of the present disclosure may be [6] "the spectroscopic measurement system according to [5], wherein the light irradiating unit has a first light source that outputs the first light and a second light source that outputs the second light, and the detection state is switched between the first state and the second state by switching the on / off state of at least one of the first light source and the second light source." In this case, the wavelength switching means can be configured by the first light source and the second light source, at least one of which can be switched the on / off state.

[0013] A spectroscopic measurement system according to one aspect of the present disclosure may be [7] "the spectroscopic measurement system according to [6], in which in the first state, both the first light source and the second light source are on, and in the second state, the second light source is on and the first light source is off, or in the first state, the first light source is on and the second light source is off, and in the second state, both the first light source and the second light source are on." In this case, the first state and the second state can be switched by turning on and off one of the first light source and the second light source while keeping the other on, thereby facilitating the operation of the first light source and the second light source.

[0014] A spectroscopic measurement system according to one aspect of the present disclosure may be [8] "the spectroscopic measurement system according to [6], wherein in the first state, the first light source is on and the second light source is off, and in the second state, the first light source is off and the second light source is on." In this case, since only one of the first light source and the second light source is on in both the first state and the second state, the process of generating spectral data can be simplified compared to, for example, switching between the first state and the second state by keeping one of the first light source and the second light source on and turning the other on and off.

[0015] A spectroscopic measurement system according to one aspect of the present disclosure may be the spectroscopic measurement system described in [5], [9] in which "the light irradiation unit includes a light output unit that outputs the first light and the second light separated from each other, and a light limiting unit that is arranged downstream of the light output unit on the optical path, the light limiting unit being capable of limiting downstream travel of at least one of the first light and the second light output from the light output unit and being capable of switching a limiting state of at least one of the first light and the second light, and the detection state being switched between the first state and the second state by switching the limiting state by the light limiting unit." In this case, the wavelength switching means can be configured by the light output unit that outputs the first light and the second light separated from each other, and the light limiting unit that is capable of switching the limiting state of at least one of the first light and the second light.

[0016] A spectroscopic measurement system according to one aspect of the present disclosure may be the spectroscopic measurement system described in [9],

[10] in which "the light-limiting unit, in the first state, limits the second light and allows the first light to travel downstream, and in the second state, allows the first light and the second light to travel downstream without limiting them, or the light-limiting unit, in the first state, allows the first light and the second light to travel downstream without limiting them, and in the second state, limits the first light and allows the second light to travel downstream." In this case, the first state and the second state can be switched by not limiting the first light and the second light in one of the first state and the second state, and limiting only one of the first light and the second light in the other of the first state and the second state. This facilitates the switching operation of the limiting state by the light-limiting unit.

[0017] A spectroscopic measurement system according to one aspect of the present disclosure may be

[11] "the spectroscopic measurement system according to [9], in which the light restricting unit restricts the second light in the first state to cause the first light to travel downstream, and restricts the first light in the second state to cause the second light to travel downstream." In this case, since only one of the first light and the second light travels downstream in both the first state and the second state, it is possible to facilitate the generation process of the spectroscopic data compared to, for example, a case in which both the first light and the second light travel downstream in either the first state or the second state.

[0018] A spectroscopic measurement system according to one aspect of the present disclosure may be

[12] "the spectroscopic measurement system according to any one of [1] to

[11] , further including a filter disposed between the spectroscopic unit and the light detection unit, which attenuates at least one of diffracted light other than the N-th order diffracted light of the first light and diffracted light other than the M-th order diffracted light of the second light." In this case, the N-th order diffracted light of the first light and the M-th order diffracted light of the second light can be more reliably detected by the light detection unit.

[0019] A spectroscopic measurement system according to one aspect of the present disclosure may be

[13] "the spectroscopic measurement system according to any one of [1] to

[12] , in which the absolute value of N is 1 and the absolute value of M is 2." In this case, it becomes possible to detect light in a wide wavelength range by dispersing the light with sufficient diffraction efficiency.

[0020] A spectroscopic measurement system according to one aspect of the present disclosure may be

[14] "the spectroscopic measurement system according to any one of [1] to

[13] , wherein the spectroscopic unit includes a spectroscopic element capable of separating light in a wavelength range of at least 1000 nm to 1500 nm into first-order diffracted light." In this case, the diffraction efficiency of the diffraction grating is high on the long-wavelength side, while the diffraction efficiency of the diffracted light is low on the short-wavelength side. However, by detecting N-order diffracted light of a first light in a first wavelength range on the long-wavelength side and M-order diffracted light of a second light in a second wavelength range on the short-wavelength side, the spectrometer can separate and detect light in a wide wavelength range with sufficient diffraction efficiency.

[0021] A spectroscopic measurement system according to one aspect of the present disclosure may be

[15] "the spectroscopic measurement system according to any one of [1] to

[14] , wherein a detection region of the photodetector that detects the N-th order diffracted light of the first light in the first state is common to a detection region of the photodetector that detects the M-th order diffracted light of the second light in the second state." In this case, a wider width per unit wavelength can be ensured in the photodetector compared to, for example, a case where the N-th order diffracted light of the first light and the M-th order diffracted light of the second light are detected in different regions in the photodetector.

[0022] A spectroscopic measurement system according to one aspect of the present disclosure may be

[16] "the spectroscopic measurement system according to any one of [6] to [8], wherein at least one of the first light source and the second light source is pulse-driven to switch the on / off state, and the detection state is alternately switched between the first state and the second state." In this case, comprehensive measurement can be performed over a wide wavelength range.

[0023] A spectroscopic measurement system according to one aspect of the present disclosure may be

[17] "the spectroscopic measurement system according to [5], wherein the light irradiating unit has a wavelength-tunable light source, and the detection state is switched between the first state and the second state by changing the wavelength of light output from the wavelength-tunable light source." In this case, the wavelength switching means can be configured using the wavelength-tunable light source.

[0024] A spectroscopic measurement system according to one aspect of the present disclosure may be

[18] "the spectroscopic measurement system according to any one of [9] to

[11] , wherein the detection state is alternately switched between the first state and the second state by switching the limiting state by the light limiting unit." In this case, comprehensive measurement can be performed over a wide wavelength range.

[0025] A spectroscopic measurement system according to one aspect of the present disclosure may be

[19] "the spectroscopic measurement system according to any one of [1] to

[18] , wherein the spectroscopic unit includes a spectroscopic element made of a blazed diffraction grating, and the blaze wavelength of the blazed diffraction grating is 1000 nm or more." In this case, the diffraction efficiency of the diffraction grating is high on the long wavelength side, while the diffraction efficiency of the diffracted light is low on the short wavelength side. However, by detecting N-order diffracted light of a first light in a first wavelength range on the long wavelength side and M-order diffracted light of a second light in a second wavelength range on the short wavelength side, this spectrometer can disperse and detect light in a wide wavelength range with sufficient diffraction efficiency.

[0026] A spectroscopic detection method according to one aspect of the present disclosure is

[20] "a spectroscopic detection method using the spectroscopic measurement system according to any one of [1] to

[19] , comprising: a first step in which the light detection unit detects N-th order diffracted light of the first light in the first state; a second step in which the light detection unit detects M-th order diffracted light of the second light in the second state; and a third step in which the processing unit generates the spectroscopic data based on the N-th order diffracted light of the first light detected in the first step and the M-th order diffracted light of the second light detected in the second step." For the reasons described above, this spectroscopic detection method can spectrally detect light in a wide wavelength range with sufficient diffraction efficiency, while ensuring a dynamic range and wavelength resolution.

[0027] A spectroscopic detection method according to one aspect of the present disclosure is

[21] "a spectroscopic detection method using the spectroscopic measurement system described in [4], comprising: a first step in which the light detection unit detects N-order diffracted light of the first light in the first state; a second step in which the light detection unit detects M-order diffracted light of the second light in the second state; and a third step in which the processing unit generates the spectroscopic data based on the N-order diffracted light of the first light detected in the first step and the M-order diffracted light of the second light detected in the second step; and before the first step, the second step, and the third step, for each of the plurality of selection filters of the filter selection unit, in a state in which the selection filter is arranged on the optical path, (1) the switching filter is not arranged upstream of the filter selection unit on the optical path, and and (2) acquiring a detection result of the photodetector in a first reference state in which both the first light and the second light are incident on the filter selection unit, and in a second reference state in which the switching filter is disposed upstream of the filter selection unit on the optical path and light other than one of the first light and the second light is blocked, wherein in the third step, the processing unit determines whether the light detected by the photodetector in the first step is N-th order diffracted light of the first light or M-th order diffracted light of the second light, based on the detection result of the photodetector in the first reference state and the detection result of the photodetector in the second reference state, and determines whether the light detected by the photodetector in the second step is N-th order diffracted light of the first light or M-th order diffracted light of the second light. In this case, even if the characteristics of a plurality of selective filters are not stored in advance, it is possible to determine whether the light detected by the photodetector using a certain selective filter is N-th order diffracted light of the first light or M-th order diffracted light of the second light.

[0028] A spectroscopic measurement system according to one aspect of the present disclosure is

[22] "a spectroscopic measurement system comprising: a light irradiation unit that irradiates an object with light; a spectroscopic unit that spectroscopically separates the light from the object irradiated by the light irradiation unit; a light detection unit that detects the light spectroscopically separated by the spectroscopic unit, the light detection unit having sensitivity to a first wavelength range and a second wavelength range shorter than the first wavelength range; and a processing unit, wherein third light including a first portion having a wavelength in the first wavelength range and a second portion having a wavelength in the second wavelength range is incident on the spectroscopic unit, and N-th order diffracted light of the first portion of the third light and M-th order diffracted light of the second portion of the third light are detected by the light detection unit, wherein N and M are integers other than 0 and the absolute value of N is smaller than the absolute value of M, and the processing unit generates spectroscopic data based on the N-th order diffracted light of the first portion of the third light and the M-th order diffracted light of the second portion of the third light detected by the light detection unit."

[0029] In this spectroscopic measurement system, third light including a first portion having a wavelength in a first wavelength range and a second portion having a wavelength in a second wavelength range is incident on a spectroscopic unit, and N-th order diffracted light of the first portion of the third light and M-th order diffracted light of the second portion of the third light are detected by a light detection unit. This makes it possible to generate spectroscopic data using the N-th order diffracted light and M-th order diffracted light, which have relatively high diffraction efficiency, and as a result, it becomes possible to spectroscopically detect light in a wide wavelength range with sufficient diffraction efficiency.

[0030] A spectroscopic measurement system according to one aspect of the present disclosure includes,

[23] "a light irradiation unit that irradiates an object with light; a spectroscopic unit that disperses the light from the object irradiated by the light irradiation unit; a light detection unit that detects the light dispersed by the spectroscopic unit, the light detection unit having sensitivity to a first wavelength range and a second wavelength range shorter than the first wavelength range; and a processing unit, wherein the light irradiation unit includes at least one (e.g., a plurality of) first light sources that output first light having a wavelength in the first wavelength range, and a plurality of second light sources that output second light having a wavelength in the second wavelength range." and at least one (e.g., a plurality of) second light sources, wherein the first light is incident on the spectroscopic section and N-th order diffracted light of the first light is detected by the photodetector, and the second light is incident on the spectroscopic section and M-th order diffracted light of the second light is detected by the photodetector, where N and M are integers other than 0 and the absolute value of N is smaller than the absolute value of M, and the processing section generates spectroscopic data based on the N-th order diffracted light of the first light and the M-th order diffracted light of the second light detected by the photodetector.

[0031] In this spectroscopic measurement system, first light having a wavelength in a first wavelength range is incident on the spectroscopic unit, and N-order diffracted light of the first light is detected by the photodetector, and second light having a wavelength in a second wavelength range is incident on the spectroscopic unit, and M-order diffracted light of the second light is detected by the photodetector. This makes it possible to generate spectroscopic data using the N-order diffracted light of the first light and the M-order diffracted light of the second light, which have relatively high diffraction efficiency, and as a result, it becomes possible to spectroscopically detect light in a wide wavelength range with sufficient diffraction efficiency.

[0032] According to one aspect of the present disclosure, it is possible to provide a spectroscopic measurement system that can disperse and detect light in a wide wavelength range with sufficient diffraction efficiency, while ensuring a dynamic range and wavelength resolution.

[0033] FIG. 1 is a configuration diagram of a spectroscopic measurement system according to an embodiment. FIG. 2 is a diagram illustrating a guide member. FIG. 3 is a diagram illustrating diffracted light detected by a light detection unit in a first state. FIG. 4 is spectral data generated by a processing unit based on detection results in the first state. FIG. 5 is a diagram illustrating diffracted light detected by a light detection unit in a second state. FIG. 6 is spectral data generated by a processing unit based on detection results in the second state. FIG. 7 is a diagram illustrating diffracted light detected by a light detection unit in a third state. FIG. 8 is spectral data generated by a processing unit based on detection results in the third state. FIG. 9 is a diagram illustrating diffracted light detected by a light detection unit in a fourth state. FIG. 10 is spectral data generated by a processing unit based on detection results in the fourth state. FIG. 11 is a flowchart illustrating a spectral detection method. FIG. 12 is a diagram illustrating a spectral image generated by a processing unit based on detection results in the first state and the second state. (a) and (b) are diagrams illustrating improvement in diffraction efficiency by a spectroscopic unit. (a) to (c) are diagrams illustrating the operation and effect of a spectroscopic measurement system according to an embodiment. FIG. 13 is a configuration diagram of a spectroscopic measurement system according to a first modified example. FIG. 14 is a configuration diagram of a spectroscopic measurement system according to a second modified example. FIG. 15 is a flowchart illustrating a spectral detection method in the second modified example. 10A to 10C are diagrams for explaining a method of specifying a detection region for detecting first-order diffracted light and second-order diffracted light in a second modified example. FIG. 10B is a configuration diagram of a spectroscopic measurement system according to a third modified example. FIG. 10C is a diagram for explaining diffracted light detected by a light detection unit in the third modified example. FIG. 10D is a flowchart for explaining a spectral detection method in the third modified example. FIG. 10E is a diagram for explaining a method for generating a spectral image in the third modified example. FIG. 10F is a configuration diagram of a spectroscopic measurement system according to a fourth modified example. FIG. 10F is a configuration diagram of a spectroscopic measurement system according to a fifth modified example. FIG. 10F is a diagram for explaining diffracted light detected by a light detection unit in the fifth modified example. FIG. 10F is a configuration diagram of a spectroscopic measurement system according to a sixth modified example. FIG. 10F is a configuration diagram of a spectroscopic measurement system according to a seventh modified example. FIG. 10F is a diagram for explaining diffracted light detected by a light detection unit in the seventh modified example. A spectral image generated by a processing unit in the seventh modified example. FIG. 10G is a configuration diagram of a spectroscopic measurement system according to an eighth modified example.

[0034] 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. [Spectroscopic Measurement System]

[0035] As shown in FIG. 1 , a spectroscopic measurement system 1 according to an embodiment includes a conveying unit 2, a light irradiating unit 3, a filter selecting unit 4 (wavelength switching means), a spectroscope 5, and a processing unit 6. In the spectroscopic measurement system 1, light is irradiated from the light irradiating unit 3 onto an object B being conveyed by the conveying unit 2 along a conveying direction A. The light irradiated from the light irradiating unit 3 and reflected or scattered by the object B is incident on the filter selecting unit 4 and the spectroscope 5, in that order, and is then dispersed and detected by the spectroscope 5. Based on the detection results, a spectral image is generated in the processing unit 6. The spectral image is an image that includes position information on the object B as well as wavelength information (spectral information) at that position. As such, in the spectroscopic measurement system 1, the spectroscope 5 is configured as a hyperspectral camera, and hyperspectral observation of the object B is performed. The spectroscope 5 can also be considered a camera module or a spectroscopic measurement module.

[0036] In this example, the transport unit 2 is a belt conveyor, and transports the object B placed on a transport surface 2a (mounting surface), which is the surface of the belt, along a transport direction A. When observing the object B (when the spectroscopic measurement system 1 is in operation), light is irradiated from the light irradiation unit 3 onto the object B being transported by the transport unit 2. This allows observation to be performed while changing the irradiation position of light on the object B, and allows the entire object B to be observed.

[0037] The light irradiation unit 3 has a light source 11 and an optical system (a lens 12, a guide member 13, and a pair of lenses 14). The light source 11 is a wide wavelength range light source configured, for example, by a halogen lamp light source or a supercontinuum light source (SC light source). The light source 11 outputs irradiation light P1, which is light having a wavelength range of, for example, 387.5 nm to 1650 nm.

[0038] The illumination light P1 is focused by the lens 12 and enters the guide member 13. The guide member 13 has a first portion 131, a second portion 132, and a third portion 133. Each of the portions 131 to 133 is tubular. One end of the first portion 131 constitutes a light entrance portion 13a, which is the portion through which the illumination light P1 enters the guide member 13. One ends of the second portion 132 and the third portion 133 are connected to the other end of the first portion 131. That is, the guide member 13 has a structure in which the other end of the first portion 131 branches into the second portion 132 and the third portion 133. The other ends of the second portion 132 and the third portion 133 each have a light exit portion 13b ( FIG. 2 ), which is the portion through which the illumination light P1 exits the guide member 13. In the guide member 13, the irradiation light P1 incident from the light incident portion 13a is guided to be emitted from each light exit portion 13b. Note that Fig. 2 shows an example of the guide member 13 in which the light exit portion 13b is provided at one end of the first portion 131 and does not have the second portion 132 or the third portion 133.

[0039] The light emitting portion 13b is formed in a flattened rectangular parallelepiped shape and has a rectangular light emitting opening 13c. Therefore, if the direction parallel to the long side of the light emitting opening 13c is defined as direction D, then irradiation light P1 spreading in direction D is emitted from the light emitting portion 13b. The light emitting portion 13b is disposed so that direction D is parallel to the conveying surface 2a and perpendicular to the conveying direction A. As a result, the object B is irradiated with irradiation light P1 spreading in a direction perpendicular to the conveying direction A (a direction perpendicular to the plane of the paper in FIG. 1 ).

[0040] If the position where the irradiation light P1 is irradiated onto the object B is defined as irradiation position X1, the pair of light emitting units 13b are respectively disposed on one side and the other side of the irradiation position X1 in the conveying direction A. The irradiation light P1 emitted from one light emitting unit 13b is focused by one of the pair of lenses 14 and irradiated onto the object B at the irradiation position X1 from one side (e.g., the upstream side) in the conveying direction A. The irradiation light P1 emitted from the other light emitting unit 13b is focused by the other of the pair of lenses 14 and irradiated onto the object B at the irradiation position X1 from the other side (e.g., the downstream side) in the conveying direction A. Each lens 14 is configured, for example, by a cylindrical lens to focus the irradiation light P1 that spreads in a direction perpendicular to the conveying direction A. By irradiating the object B with light from both sides in the conveying direction A in this manner, light can be suitably irradiated onto an object B having a three-dimensional shape.

[0041] The illumination light P1 emitted from the light irradiation unit 3 and reflected or scattered by the object B is incident on the filter selection unit 4. The filter selection unit 4 switches its detection state between first to fourth states, as described below. The filter selection unit 4 is disposed between the irradiation position X1 (object B) and the spectrometer 5. The filter selection unit 4 has a plurality of selection filters, including a first filter 21, a second filter 22, a third filter 23, and a fourth filter 24. The filters 21 to 24 are disposed, for example, in a plurality of openings formed in a plate-shaped main body 25. The filter selection unit 4 is a filter changer that rotates the main body 25 using a drive unit (not shown) to position a selected filter from the filters 21 to 24 on the optical path of the illumination light P1. The operation of the filter selection unit 4 (drive unit) is controlled by the processing unit 6. The filters 21 to 24 disposed on the optical path transmit light in a predetermined wavelength range contained in the illumination light P1 and block light other than the predetermined wavelength range. In this way, the filter selection unit 4 selects a filter disposed on the optical path of the irradiation light P1, thereby configuring a wavelength switching means that selects (limits) the wavelength of light detected by the spectroscope 5. The characteristics of each of the filters 21 to 24 will be described later.

[0042] The spectroscope 5 has a slit section 31, a spectroscopic section 32, a diffracted light blocking filter 33 (filter), a light detecting section 34, and a housing 35. The housing 35 is formed, for example, in a box shape, and houses the slit section 31, the spectroscopic section 32, the diffracted light blocking filter 33, and the light detecting section 34.

[0043] Light P2 that has passed through any of the filters 21 to 24 enters the slit section 31. The slit section 31 is, for example, a rectangular flat plate-shaped member in which a slit 31a is formed. The slit section 31 is arranged so that the extension direction of the slit 31a is parallel to the conveying surface 2a and perpendicular to the conveying direction A. The slit 31a transmits at least a portion of the light P2 and emits it toward the spectroscopic section 32. With regard to the light P2 from the slit 31a, the position in the extension direction of the slit 31a represents position information of the object B along the direction perpendicular to the conveying direction A.

[0044] The spectroscopic unit 32 splits the light P2 from the slit 31a. The spectroscopic unit 32 is a reflective spectroscopic element made of, for example, a blazed diffraction grating. The spectroscopic unit 32 is configured to be able to split light in at least a wavelength range of 1000 nm to 1500 nm into first-order diffracted light. "Able to split light in a certain wavelength range into first-order diffracted light" means, for example, that the diffraction efficiency of first-order diffracted light in that wavelength range is 30% or higher. In this example, the spectroscopic unit 32 is able to split the light P2 in a wavelength range of 800 nm to 1800 nm into first-order diffracted light. The blazed wavelength of the blazed diffraction grating that constitutes the spectroscopic unit 32 is, for example, 1000 nm or higher, and in this example, is 1200 nm. The light split by the spectroscopic unit 32 includes diffracted light of the light P2, such as zeroth-order diffracted light, first-order diffracted light, second-order diffracted light, third-order diffracted light, and so on. Hereinafter, zeroth-order diffracted light, first-order diffracted light, second-order diffracted light, third-order diffracted light, etc. will also be referred to as zeroth-order light, first-order light, second-order light, third-order light, etc. The light from the spectroscopic unit 32 is incident on a diffracted light blocking filter 33. Note that the spectroscopic unit 32 may be a transmission type spectroscopic element made of a prism or the like, or a spectroscopic element made of a holographic diffraction grating, depending on the design.

[0045] The diffracted light blocking filter 33 is disposed between the spectroscopic unit 32 and the light detecting unit 34, and in this example, is fixed on the light detection region 34a of the light detecting unit 34. The diffracted light blocking filter 33 functions as an order sorting filter that transmits predetermined diffracted light contained in the light incident on the diffracted light blocking filter 33 and blocks diffracted light other than the predetermined diffracted light. Details of the diffracted light blocked by the diffracted light blocking filter 33 will be described later. The light that has passed through the diffracted light blocking filter 33 is incident on the light detecting unit 34.

[0046] The light dispersed by the spectroscopic unit 32 enters the photodetection region 34a of the photodetector 34, and the light is detected by the photodetector 34. In this example, the sensitivity wavelength range of the photodetector 34 is, for example, 380 nm to 1700 nm, and includes a first wavelength range of 775 nm to 1650 nm and a second wavelength range of 387.5 nm to 825 nm that is shorter than the first wavelength range. In this example, the photodetector 34 is an InGaAs image sensor. Note that the photodetector 34 may also be a charge-coupled device (CCD) image sensor or a complementary metal-oxide semiconductor (CMOS) image sensor.

[0047] The light detection unit 34 has a plurality of pixels aligned in a direction corresponding to the direction of light splitting by the spectroscopic unit 32 and a direction perpendicular to that direction. The light detection unit 34 is arranged, for example, so that that direction is parallel to the direction of light splitting by the spectroscopic unit 32. That is, in the light detection unit 34, a plurality of pixels are arranged two-dimensionally in a matrix. In the light detection unit 34, the position in that direction represents wavelength information, and the position in the direction perpendicular to that direction represents position information of the object B along a direction perpendicular to the conveying direction A.

[0048] The processing unit 6 is communicably connected to the light detection unit 34 and generates a spectroscopic image (spectroscopic data) based on the detection results of the light detection unit 34. The processing unit 6 is configured by, for example, a computer including a processor (CPU) and recording media such as RAM and ROM. As described above, the processing unit 6 also controls the filter selection unit 4. The processing unit 6 controls the filter selection unit 4 to switch the filter placed on the optical path of the irradiation light P1 between the filters 21 to 24, thereby switching the detection state in the spectroscopic measurement system 1 between first to fourth states described below. [First to Fourth States]

[0049] The following describes the diffracted light detected by the light detection unit 34 and the spectral data generated by the processing unit 6 in each of the first to fourth detection states. In this example, the state in which the first filter 21 is disposed on the optical path of the irradiation light P1 is defined as the first state, the state in which the second filter 22 is disposed on the optical path is defined as the second state, the state in which the third filter 23 is disposed on the optical path is defined as the third state, and the state in which the fourth filter 24 is disposed on the optical path is defined as the fourth state.

[0050] Referring to FIG. 3, the diffracted light detected by the photodetector 34 in the first state will be described together with the characteristics of the first filter 21. The horizontal axis of the graph in FIG. 3 represents position on the photodetector 34 (photodetection region 34a) (position in a direction corresponding to the spectroscopic direction of the spectroscopic section 32), and the vertical axis represents wavelength. This also applies to FIGS. 5, 7, and 9, which will be described later. FIG. 3 shows first to fourth order light separated by the spectroscopic section 32. As shown in FIG. 3, when the position in the spectroscopic direction is the same, the wavelength of the Lth order light (L is an integer greater than or equal to 1) is 1 / L of the wavelength of the first order light.

[0051] The first filter 21 is a long-pass filter that transmits light of 800 nm or greater (transmission band) and blocks light of 800 nm or less. In FIG. 3 , the transmission band of the first filter 21 is labeled "800 nm long-pass filter." In this example, first light L1 ( FIG. 1 ) in the wavelength range of 800 nm to 1650 nm or greater of the irradiation light P1, which includes a wavelength range of 387.5 nm to 1650 nm, passes through the first filter 21. The wavelength range of the first light L1 overlaps with at least a portion (800 nm to 1650 nm in this example) of the first wavelength range (775 nm to 1650 nm) of the photodetector 34. In other words, the first light L1 is light having a wavelength in the first wavelength range, and in this example, it contains only light in the first wavelength range. In the first state, the first light L1 is split by the spectroscopic unit 32, and the diffracted light of the first light L1 is detected by the photodetector 34.

[0052] In FIG. 3 , a detection region R1, which indicates the position and wavelength range detected by the light detection unit 34, is indicated by a rectangular dotted line. The detection region R1 corresponds to the light detection region 34a of the light detection unit 34. A blocking region R2, which indicates the position and wavelength range where the diffracted light blocking filter 33 blocks light, is indicated by a rectangular dashed line. In this example, the light detection unit 34 detects light in the wavelength range of 387.5 nm to 1650 nm that is incident at a position between 12 mm and 26 mm. The diffracted light blocking filter 33 is disposed at a position between 20 mm and 28 mm. In this example, the diffracted light blocking filter 33 has the characteristic of blocking light with a wavelength of less than 600 nm. In the first state (a state in which light of 800 nm or more is incident on the light detection unit 34), the diffracted light of the first light L1 is not blocked by the diffracted light blocking filter 33. In this way, in the first state, the primary light of the first light L1 that has passed through the first filter 21 enters the detection region R1, while the other diffracted light of the first light L1 does not enter the detection region R1. Therefore, only the primary light of the first light L1 is detected by the light detection unit 34.

[0053] As described above, in the first state, the first filter 21 is positioned on the optical path of the irradiation light P1 by the filter selection unit 4, and the irradiation light P1 from the light irradiation unit 3 is irradiated onto the object B. Then, the irradiation light P1 reflected or scattered by the object B is incident on the first filter 21, and the first light L1 transmitted through the first filter 21 is dispersed by the spectroscopic unit 32. Then, only the primary light of the first light L1 is incident on the photodetection region 34a of the photodetector 34, and only the primary light is detected by the photodetector 34.

[0054] As shown in Fig. 4, the processing unit 6 generates spectral data based on the primary light of the first light L1 detected in the first state. In this example, the processing unit 6 pre-stores the type of diffracted light (filter data) detected by the light detection unit 34 in each of the first to fourth detection states. Then, based on the filter data, the processing unit 6 converts the luminance at each position on the light detection unit 34 detected in the first state into the luminance of the diffracted light corresponding to each position, thereby generating spectral data. In the example of Fig. 4, the luminance at positions 13 mm to 26 mm detected by the light detection unit 34 is treated as the luminance of light in the wavelength range of 800 nm to 1600 nm, thereby generating spectral data.

[0055] Referring to FIG. 5, the diffracted light detected by the photodetector 34 in the second state will be described along with the characteristics of the second filter 22. The second filter 22 is a short-pass filter that transmits light of 800 nm or less (transmission band) and blocks light of 800 nm or more. Thus, in the second state, the wavelength range of light transmitted through the filter selection unit 4 is different from that in the first state. In FIG. 5, the transmission band of the second filter 22 is labeled "800 nm short-pass filter." In this example, second light L2 (FIG. 1) in the wavelength range of 387.5 nm to 800 nm or less of the irradiation light P1, which includes a wavelength range of 387.5 nm to 1650 nm, is transmitted through the second filter 22. The wavelength range of the second light L2 overlaps with at least a portion (387.5 nm to 800 nm in this example) of the second wavelength range (387.5 nm to 825 nm) of the photodetector 34. In other words, the second light L2 is light having a wavelength in the second wavelength range, and in this example, it is light that contains only light in the second wavelength range. In the second state, the second light L2 is split by the splitting unit 32, and the diffracted light of the second light L2 is detected by the light detecting unit 34.

[0056] 5, the second-order light of the second light L2 is incident on a position between 13 mm and 26 mm into the detection region R1. The diffracted light blocking filter 33 blocks diffracted light other than the second-order light of the second light L2 (in this example, the third-order light). In other words, the third-order light of the second light L2 is blocked by the diffracted light blocking filter 33 and does not enter the detection region R1.

[0057] As described above, in the second state, the second filter 22 is positioned on the optical path of the irradiation light P1 by the filter selection unit 4, and the irradiation light P1 from the light irradiation unit 3 is irradiated onto the object B. The irradiation light P1 reflected or scattered by the object B is incident on the second filter 22, and the second light L2 transmitted through the second filter 22 is dispersed by the spectroscopic unit 32. The secondary light of the second light L2 is incident on the photodetection region 34a of the photodetection unit 34, and the secondary light is detected by the photodetection unit 34. At this time, the tertiary light of the second light L2 is blocked by the diffracted light blocking filter 33 and does not enter the detection region R1.

[0058] As shown in FIG. 6 , the processing unit 6 generates spectral data based on the secondary light of the second light L2 detected in the second state. As in the first state, the processing unit 6 generates spectral data by converting the luminance at each position on the light detection unit 34 detected in the second state into the luminance of the diffracted light corresponding to each position based on the filter data. In the example of FIG. 6 , the processing unit 6 generates spectral data by treating the luminance at a position between 13 mm and 26 mm detected by the light detection unit 34 as the luminance of light in a wavelength range between 400 nm and 800 nm. In this way, in the first state and the second state, the luminance detected at the same position between 13 mm and 26 mm on the light detection unit 34 is acquired as the luminance of light in different wavelength ranges. This is because the wavelength of the secondary light is half the wavelength of the primary light when the position in the spectral direction is the same.

[0059] Referring to FIG. 7 , the diffracted light detected by the light detector 34 in the third state will be described along with the characteristics of the third filter 23. The third filter 23 is a bandpass filter that transmits light in the 550 nm to 1100 nm (transmission band) range and blocks light with wavelengths shorter than 550 nm and light with wavelengths longer than 1100 nm. In FIG. 7 , the transmission band of the third filter 23 is indicated as a "550 to 1100 nm bandpass filter." In this example, the third light L3 ( FIG. 1 ) in the wavelength range of 550 nm to 1100 nm of the irradiation light P1, which includes a wavelength range of 387.5 nm to 1650 nm, passes through the third filter 23. The wavelength range of the third light L3 includes a first portion C1 (775 nm to 1100 nm in this example) having a wavelength in the first wavelength range (775 nm to 1650 nm) and a second portion C2 (550 nm to approximately 825 nm in this example) having a wavelength in the second wavelength range (387.5 nm to 825 nm). The first portion C1 overlaps with at least a portion of the first wavelength range (a portion on the short wavelength side in this example), and the second portion C2 overlaps with at least a portion of the second wavelength range (a portion on the long wavelength side in this example). In the third state, the light of the first portion C1 and the light of the second portion C2 are split by the splitting unit 32, and the diffracted light of the light of the first portion C1 and the diffracted light of the light of the second portion C2 are detected by the light detection unit 34.

[0060] In FIG. 7 , the light detection unit 34 detects the first-order light of the first portion C1 of the third light L3 incident at a position between 12 mm and 17.5 mm, and detects the second-order light of the second portion C2 of the third light L3 incident at a position between 17.5 mm and 26 mm. The diffracted light blocking filter 33 blocks diffracted light other than the second-order light of the third light L3 (in this example, the third-order light). In other words, the third-order light of the third light L3 is blocked by the diffracted light blocking filter 33 and does not enter the detection region R1. In this example, the first-order light and the second-order light are detected in two regions of the light detection region 34a, each separated by a boundary at 17.5 mm. In other words, in the third state, the first-order light and the second-order light are detected by the light detection unit 34 without overlapping in the spectral direction.

[0061] As shown in FIG. 8 , the processing unit 6 generates spectral data for the primary and secondary light of the third light L3 based on the primary and secondary light of the third light L3 detected in the third state. As in the first state, the processing unit 6 generates spectral data by converting the luminance at each position on the light detection unit 34 detected in the third state into the luminance of the diffracted light corresponding to each position based on the filter data. In the example of FIG. 8 , the luminance at the position from 12 mm to 17.5 mm detected by the light detection unit 34 is defined as the luminance of light in the wavelength range from 775 nm to 1100 nm, and the luminance at the position from 17.5 mm to 26 mm is defined as the luminance of light in the wavelength range from 550 nm to 825 nm, thereby generating spectral data indicating the luminance of the primary and secondary light of the third light L3. In the example of FIG. 8 , the luminance in the wavelength range (775 nm to 825 nm) where the primary and secondary light overlap is the sum of the luminance of the primary and secondary light.

[0062] Referring to FIG. 9 , the diffracted light detected by the photodetector 34 in the fourth state will be described along with the characteristics of the fourth filter 24. The fourth filter 24 is a notch filter that transmits light of 650 nm or less (transmission band) and light of 1300 nm or more (transmission band) and blocks light of wavelengths greater than 650 nm and less than 1300 nm. In FIG. 9 , the wavelength range blocked by the fourth filter 24 is indicated as a "650-1300 nm notch filter." In this example, the fourth light L4 ( FIG. 1 ) including light of the wavelength range 1300 nm to 1650 nm and light of the wavelength range 387.5 nm to 650 nm of the irradiation light P1 including the wavelength range 387.5 nm to 1650 nm passes through the fourth filter 24. The wavelength range of the fourth light L4 includes a third portion C3 (1300 nm to 1650 nm in this example) having a wavelength in the first wavelength range (775 nm to 1650 nm) and a fourth portion C4 (387.5 nm to 650 nm in this example) having a wavelength in the second wavelength range (387.5 nm to 825 nm). The third portion C3 overlaps with at least a portion of the first wavelength range (a portion on the long wavelength side in this example), and the fourth portion C4 overlaps with at least a portion of the second wavelength range (a portion on the short wavelength side in this example). In the fourth state, the light of the third portion C3 and the light of the fourth portion C4 are split by the splitting unit 32, and the diffracted light of the light of the third portion C3 and the diffracted light of the light of the fourth portion C4 are detected by the light detection unit 34.

[0063] In FIG. 9 , the light detection unit 34 detects the first-order light of the third portion C3 of the fourth light L4 incident at a position between 21 mm and 26 mm, and detects the second-order light of the fourth portion C4 of the fourth light L4 incident at a position between approximately 13 mm and 21 mm. The diffracted light blocking filter 33 blocks diffracted light other than the second-order light of the fourth light L4 (in this example, the third-order light). In other words, the third-order light of the fourth light L4 is blocked by the diffracted light blocking filter 33 and does not enter the detection region R1. In this example, the first-order light and the second-order light are detected in two regions of the light detection region 34a, each separated by a boundary at 21 mm. In other words, in the fourth state, as in the third state, the first-order light and the second-order light are detected by the light detection unit 34 without overlapping in the light detection region 34a.

[0064] As shown in Fig. 10 , the processing unit 6 generates spectral data for the primary and secondary lights of the fourth light L4 based on the primary and secondary lights of the fourth light L4 detected in the fourth state. As in the first state, the processing unit 6 generates spectral data by converting the luminance at each position on the light detection unit 34 detected in the fourth state into the luminance of the diffracted light corresponding to each position based on the filter data. In the example of Fig. 10 , the processing unit 6 generates spectral data indicating the luminance of the primary and secondary lights of the fourth light L4 by defining the luminance at a position between 21 mm and 26 mm detected by the light detection unit 34 as the luminance of light in the wavelength range of 1300 nm to 1650 nm, and the luminance at a position between approximately 13 mm and 21 mm as the luminance of light in the wavelength range of 387.5 nm to 650 nm. [Spectral Detection Method]

[0065] 11 , a spectroscopic detection method using the spectroscopic measurement system 1 will be described. First, in a first state, the primary light of the first light L1 is detected by the light detection unit 34 (step S11 (first step)). In step S11, the filter selection unit 4 first places the first filter 21 on the optical path and switches the detection state to the first state. In this first state, the light irradiation unit 3 irradiates the object B with irradiation light P1. The irradiation light P1 reflected or scattered by the object B is incident on the first filter 21, and the first light L1 transmitted through the first filter 21 is dispersed by the spectroscopic unit 32. The primary light of the first light L1 from the spectroscopic unit 32 is incident on the light detection region 34a of the light detection unit 34, and the primary light of the first light L1 is detected by the light detection unit 34.

[0066] Subsequently, in the second state, the secondary light of the second light L2 is detected by the light detection unit 34 (step S12 (second step)). In step S12, first, the filter selection unit 4 places the second filter 22 on the optical path and switches the detection state to the second state. In this second state, the light irradiation unit 3 irradiates the object B with the irradiation light P1. The irradiation light P1 reflected or scattered by the object B is incident on the second filter 22, and the second light L2 transmitted through the second filter 22 is dispersed by the spectroscopic unit 32. The secondary light of the second light L2 from the spectroscopic unit 32 is incident on the light detection region 34a of the light detection unit 34, and the secondary light of the second light L2 is detected by the light detection unit 34.

[0067] Next, the processing unit 6 generates a spectral image based on the primary light of the first light L1 detected in step S11 and the secondary light of the second light L2 detected in step S12 (step S13 (third step)). For example, as shown in FIG. 12 , the processing unit 6 generates spectral data on the primary light and secondary light from the detection results of the primary light of the first light L1 in the first state (spectral data D1) and the detection results of the secondary light of the second light L2 in the second state (spectral data D2), and generates a spectral image E1 based on this spectral data (by stitching together the spectral data D1 and D2). Note that, as will be described later, the spectroscopic measurement system 1 may detect the primary light and secondary light in a third state (fourth state) and generate a spectral image further based on the detection results of the primary light and secondary light in the third state (fourth state). [Operation and Effects]

[0068] As described above, in the spectroscopic measurement system 1, the filter selection unit 4 can switch the detection state between a first state in which the first light L1 having a wavelength in a first wavelength range is incident on the spectroscopic unit 32 and the primary light of the first light L1 is detected by the photodetector 34, and a second state in which the second light L2 having a wavelength in a second wavelength range is incident on the spectroscopic unit 32 and the secondary light of the second light L2 is detected by the photodetector 34. A spectral image is generated based on the primary light of the first light L1 detected in the first state and the secondary light of the second light L2 detected in the second state. This makes it possible to generate a spectral image using the primary light of the first light L1 and the secondary light of the second light L2, which have relatively high diffraction efficiency, and as a result, it becomes possible to spectroscopically detect light in a wide wavelength range with sufficient diffraction efficiency.

[0069] This point will be further explained with reference to FIG. 13 . FIG. 13( a) shows an example of a simulation result of the diffraction efficiency of a diffraction grating with a blaze wavelength of 600 nm, and FIG. 13( b) shows an example of a simulation result of the diffraction efficiency of a diffraction grating with a blaze wavelength of 1200 nm. For example, when light is dispersed using the diffraction grating shown in FIG. 13( a) and the resulting first-order light is detected, the diffraction efficiency is low in the long-wavelength region. In contrast, by dispersing light using the diffraction grating shown in FIG. 13( b), for example, and using the first-order light for a first wavelength range on the long-wavelength side (e.g., 800 nm or more) and the second-order light for a second wavelength range on the short-wavelength side (e.g., 800 nm or less), the first-order light of the first light L1 and the second-order light of the second light L2, which have relatively high diffraction efficiencies, can be detected by the light detection unit 34. This makes it possible to disperse and detect light over a wide wavelength range with sufficient diffraction efficiency.

[0070] Furthermore, in the spectroscopic measurement system 1, in the first state, the primary light of the first light L1 is detected by the photodetector 34, and in the second state, the secondary light of the second light L2 is detected by the photodetector 34. Therefore, for example, the primary light and the secondary light can be detected in a common region (photodetection region 34a in this example) in the photodetector 34. This makes it possible to prevent the width (pitch) per unit wavelength in the photodetector 34 from becoming narrow, even when the size of the photodetector 34 is small, and ensures the dynamic range and wavelength resolution.

[0071] This point will be further explained with reference to FIGS. 14( a) to 14(c). FIG. 14(a) shows a photodetector 134 having a wavelength sensitivity range of 400 nm to 1000 nm, while FIGS. 14(b) and 14(c) show the photodetector 34 of the above embodiment. Note that in the examples of FIGS. 14(b) and 14(c), the wavelength sensitivity range of the photodetector 34 is the same as the wavelength sensitivity range of the photodetector 34 of the above embodiment (380 nm to 1700 nm). Compared to the photodetector 134, the wavelength sensitivity range of the photodetector 34 is relatively wide, but the size of the photodetector 34 is relatively small. This is because it is difficult to manufacture a sensor with a wide wavelength sensitivity range. Because the sensor size is small yet the wavelength sensitivity range is wide, as shown in FIG. 14(b), when light of 380 nm to 1700 nm is incident on the photodetection region 34a, the width (pitch) per unit wavelength becomes narrow, resulting in a narrow dynamic range. 14(c), by allowing primary light of 775 nm to 1650 nm to be incident on the photodetection region 34a in the first state and allowing secondary light of 387.5 nm to 825 nm to be incident on the photodetection region 34a in the second state, it is possible to widen the width per unit wavelength in each detection state, thereby ensuring a sufficient dynamic range.

[0072] As described above, the spectroscopic measurement system 1 can disperse and detect light in a wide wavelength range with sufficient diffraction efficiency, and can also ensure a sufficient dynamic range and wavelength resolution.

[0073] Furthermore, the spectroscopic measurement system 1 can increase the degree of freedom in detection and can be appropriately adapted to multiple applications. Specifically, the spectroscopic measurement system 1 may be used to detect foreign matter. In this case, the system is required to be able to detect light in a wide wavelength range, and low detection efficiency is acceptable. On the other hand, when performing preliminary measurement to set conditions for foreign matter detection, improved detection efficiency and detection speed are required, and a narrower wavelength range may be acceptable. For the former application, the spectroscopic measurement system 1 can detect light in a wide wavelength range, for example, by switching between the first state and the second state. Additionally, for the latter application, the spectroscopic measurement system 1 can improve detection efficiency and detection speed by using only the detection results in the first state and not performing light detection in other detection states. Thus, the spectroscopic measurement system 1 can increase the degree of freedom in detection and can be appropriately adapted to multiple applications.

[0074] In the spectroscopic measurement system 1, the wavelength switching means is configured by a filter selection unit 4 that arranges on the optical path a filter selected from a plurality of selection filters including a first filter 21 that transmits the first light L1 and blocks light other than the first light L1, and a second filter 22 that transmits the second light L2 and blocks light other than the second light L2, and in the first state, the first filter 21 is arranged on the optical path, and in the second state, the second filter 22 is arranged on the optical path. Thus, the wavelength switching means can be configured by the filter selection unit 4 that arranges on the optical path a filter selected from the plurality of selection filters.

[0075] The spectroscopic measurement system 1 includes a diffracted light blocking filter 33 disposed between the spectroscopic unit 32 and the light detecting unit 34, which blocks diffracted light (third-order light in this example) other than the second-order light of the second light L2. This allows the second-order light of the second light to be detected more reliably by the light detecting unit 34.

[0076] In the spectroscopic measurement system 1, the spectroscopic unit 32 includes a spectroscopic element capable of separating light in at least a wavelength range of 1000 nm to 1500 nm into primary light. When the spectroscopic unit 32 is configured in this manner, as shown in FIG. 13B , for example, the diffraction efficiency of the spectroscopic unit 32 for primary light is high on the long wavelength side, while the diffraction efficiency of the primary light is low on the short wavelength side. Furthermore, on the short wavelength side, the diffraction efficiency of the primary light is higher than the diffraction efficiency of the secondary light. Therefore, the spectroscopic measurement system 1 uses such a spectroscopic element to detect primary light of the first light L1 in a first wavelength range on the long wavelength side, and detect secondary light of the second light L2 in a second wavelength range on the short wavelength side. This allows light in a wide wavelength range to be separated and detected with sufficient diffraction efficiency.

[0077] In the spectroscopic measurement system 1, the spectroscopic unit 32 includes a spectroscopic element made of a blazed diffraction grating, and the blaze wavelength of the blazed diffraction grating is 1000 nm or more, for example, 1200 nm. When the blaze wavelength is set to the long wavelength side in this manner, the diffraction efficiency of the spectroscopic unit 32 for first-order light is high on the long wavelength side, while the diffraction efficiency of first-order light is low on the short wavelength side, as shown in FIG. 13B . Furthermore, on the short wavelength side, the diffraction efficiency of first-order light is higher than the diffraction efficiency of second-order light. Therefore, the spectroscopic measurement system 1 uses such a spectroscopic element to detect first-order light of the first light L1 in a first wavelength range on the long wavelength side, and detect second-order light of the second light L2 in a second wavelength range on the short wavelength side. This allows light in a wide wavelength range to be dispersed and detected with sufficient diffraction efficiency.

[0078] In the spectroscopic measurement system 1, the detection region of the light detection unit 34 that detects the primary light of the first light L1 in the first state is common to the detection region of the light detection unit 34 that detects the secondary light of the second light L2 in the second state. In this example, the primary light and the secondary light are detected in the same light detection region 34a. This makes it possible to ensure a wider width per unit wavelength in the light detection unit 34 compared to, for example, a case where the primary light of the first light L1 and the secondary light of the second light L2 are detected in different regions in the light detection unit 34. [Modification of the embodiment]

[0079] In the spectroscopic detection method, step S11 is performed before step S12, but step S11 may be performed after step S12. In addition to steps S11 and S12, the spectroscopic detection method may further include a step of detecting the primary light and the secondary light in a third state (hereinafter also referred to as a "third state step"), and a step of detecting the primary light and the secondary light in a fourth state (hereinafter also referred to as a "fourth state step").

[0080] In the third state step, first, the filter selection unit 4 places the third filter 23 on the optical path and switches the detection state to the third state. In this third state, the light irradiation unit 3 irradiates the object B with irradiation light P1. The irradiation light P1 reflected or scattered by the object B is incident on the third filter 23, and the third light L3 transmitted through the third filter 23 is dispersed by the spectroscopic unit 32. The primary light of the first portion C1 of the third light L3 from the spectroscopic unit 32 and the secondary light of the second portion C2 of the third light L3 are incident on the photodetection region 34a of the photodetector 34 and detected by the photodetector 34.

[0081] In the fourth state step, first, the filter selection unit 4 places the fourth filter 24 on the optical path and switches the detection state to the fourth state. In this fourth state, the light irradiation unit 3 irradiates the object B with irradiation light P1. The irradiation light P1 reflected or scattered by the object B is incident on the fourth filter 24, and the fourth light L4 transmitted through the fourth filter 24 is split by the spectroscopic unit 32. The primary light of the third portion C3 of the fourth light L4 from the spectroscopic unit 32 and the secondary light of the fourth portion C4 of the fourth light L4 are incident on the photodetection region 34a of the photodetector 34 and detected by the photodetector 34.

[0082] The order of step S11, step S12, the third state step, and the fourth state step is not particularly limited and may be any order. In this case, in the spectroscopic measurement system 1, the processing unit 6 may generate a spectral image based on the detection results of the primary light of the first light L1 in the first state and the detection results of the secondary light of the second light L2 in the second state, as well as the detection results of the primary light and secondary light of the third light L3 in the third state and the detection results of the primary light and secondary light of the fourth light L4 in the fourth state.

[0083] The spectral detection method may include a third state step in addition to steps S11 and S12, but not a fourth state step. In this case, in the spectroscopic measurement system 1, the processing unit 6 may generate a spectral image based on the primary light of the first portion C1 of the third light L3 and the secondary light of the second portion C2 of the third light L3 detected in the third state, in addition to the detection result of the primary light of the first light L1 in the first state and the detection result of the secondary light of the second light L2 in the second state. Alternatively, the spectroscopic detection method may include a fourth state step in addition to steps S11 and S12, but not the third state step. In this case, in the spectroscopic measurement system 1, the processing unit 6 may generate a spectral image based on the primary light of the third portion C3 of the fourth light L4 and the secondary light of the fourth portion C4 of the fourth light L4 detected in the fourth state, in addition to the detection result of the primary light of the first light L1 in the first state and the detection result of the secondary light of the second light L2 in the second state. This allows a spectral image to be generated further based on the detection result of the third light L3 (fourth light L4) having wavelengths in both the first wavelength range and the second wavelength range.

[0084] The spectroscopic measurement system 1 may generate a spectroscopic image based on the detection results in at least two of the first to fourth detection states. For example, the spectroscopic measurement system 1 may generate a spectroscopic image based on the detection result in the first state and the detection result in the third state or the fourth state. Alternatively, the spectroscopic measurement system 1 may generate a spectroscopic image based on the detection result in the second state and the detection result in the third state or the fourth state. [First Modification]

[0085] In a spectroscopic measurement system 1 according to a first modification shown in FIG. 15 , the filter selector 4 of the above embodiment is disposed between the light source 11 and the lens 12. In the first modification, the illumination light P1 output from the light source 11 is directly incident on one of the filters 21 to 24 of the filter selector 4. The first light L1 transmitted through the first filter 21 enters the guide member 13 and is irradiated onto the object B. The first light L1 reflected or scattered by the object B enters the spectroscope 5, where it is dispersed and detected. The second light L2 transmitted through the second filter 22, the third light L3 transmitted through the third filter 23, and the fourth light L4 transmitted through the fourth filter 24 are also dispersed and detected in the spectroscope 5. This first modification, like the above embodiment, allows for dispersion and detection of light in a wide wavelength range with sufficient diffraction efficiency, while ensuring a sufficient dynamic range and wavelength resolution. [Second Modification]

[0086] In the second modified example shown in FIG. 16 , similar to the first modified example, the filter selector 4 is disposed between the light source 11 and the lens 12. Furthermore, the spectroscopic measurement system 1 further includes a switching unit 7 disposed upstream of the filter selector 4 on the optical path (closer to the light source 11). In this example, the switching unit 7 is disposed between the light source 11 and the filter selector 4. The switching unit 7 includes a switching filter 41 and a main body 42 in which the switching filter 41 is operably disposed. The switching unit 7 positions the switching filter 41 on the optical path of the irradiation light P1 by operating the main body 42 using a driving unit (not shown). The operation of the switching unit 7 (driving unit) is controlled by the processing unit 6. Light transmitted through the switching filter 41 is incident on one of the filters 21 to 24.

[0087] The switching filter 41 is a long-pass filter that transmits light of 800 nm or greater (transmission band) and blocks light of 800 nm or less. In this example, the switching filter 41 transmits a first light L1 in the wavelength range of 800 nm to 1650 nm of the irradiation light P1, which includes a wavelength range of 387.5 nm to 1650 nm, and blocks a second light L2 in the wavelength range of 387.5 nm to 800 nm or less of the irradiation light P1. The switching unit 7 can switch between a first reference state in which the switching filter 41 is not disposed on the optical path and both the first light L1 and the second light L2 (irradiation light P1) are incident on the filter selection unit 4, and a second reference state in which the switching filter 41 is disposed on the optical path and the second light L2 is blocked (a state in which the first light L1 is incident on the filter selection unit 4).

[0088] Next, a spectroscopic detection method using the spectroscopic measurement system 1 according to the second modification will be described. As shown in FIG. 17 , the spectroscopic detection method further includes an acquisition step (steps S21 to S24) in addition to steps S11 to S13 of the above embodiment. The acquisition step is performed for each of the filters 21 to 24. Hereinafter, the acquisition steps performed for the filters 21 to 24 will be referred to as the first acquisition step, second acquisition step, third acquisition step, and fourth acquisition step, respectively. The first acquisition step, second acquisition step, third acquisition step, and fourth acquisition step are performed before steps S11 to S13 of the above embodiment. Details of the fourth acquisition step will be described below, but the same applies to the first to third acquisition steps.

[0089] First, instead of the conveying unit 2, a white reference surface W ( FIG. 16 ) is placed at a position where light from the guide member 13 is irradiated. This reference surface W uniformly reflects light. Then, the filter selection unit 4 places the fourth filter 24 on the optical path, and the switching unit 7 switches the state to a first reference state in which the switching filter 41 is not placed on the optical path. In this first reference state, the light irradiating unit 3 outputs irradiation light P1. The irradiation light P1 is incident on the fourth filter 24, and the fourth light L4 that passes through the fourth filter 24 is reflected by the reference surface W. The fourth light L4 reflected by the reference surface W is split by the spectroscopic unit 32. The diffracted light of the fourth light L4 from the spectroscopic unit 32 is incident on the photodetection region 34a of the photodetector 34 and detected by the photodetector 34 (step S21). In step S21, since the switching filter 41 that blocks the second light L2 is not positioned on the optical path, both the primary light of the third part C3 of the fourth light L4 and the secondary light of the fourth part C4 of the fourth light L4 are detected, as shown in Figure 18 (a).

[0090] Next, the switching unit 7 switches the state to a second reference state in which the switching filter 41 is disposed on the optical path. In this second reference state, the light irradiation unit 3 outputs irradiation light P1. The irradiation light P1 is incident on the switching filter 41, and the first light L1 that passes through the switching filter 41 is incident on the fourth filter 24. When the first light L1 enters the fourth filter 24, the light of the third portion C3 (1300 nm to 1650 nm) of the fourth light L4 passes through the fourth filter 24. The light of the third portion C3 of the fourth light L4 that is output from the fourth filter 24 is irradiated onto the object B. The light of the third portion C3 of the fourth light L4 that is reflected or scattered by the object B is split by the spectroscopic unit 32. The diffracted light of the third portion C3 of the fourth light L4 from the spectroscopic unit 32 is incident on the photodetection region 34a of the photodetector 34 and detected by the photodetector 34 (step S22). In step S22, since the switching filter 41 that blocks the second light L2 is arranged on the optical path, only the primary light of the third portion C3 of the fourth light L4 is detected, as shown in FIG. 18(b).

[0091] The detection result (first luminance) by the light detection unit 34 in the first reference state includes the luminance of both the primary light of the third portion C3 of the fourth light L4 and the secondary light of the fourth portion C4 of the fourth light L4. The detection result (second luminance) by the light detection unit 34 in the second reference state includes the luminance of only the primary light of the third portion C3 of the fourth light L4. Therefore, as shown in FIG. 18C, the processing unit 6 can obtain a third luminance corresponding to the secondary light of the fourth portion C4 of the fourth light L4 by subtracting the second luminance from the first luminance at each position on the light detection unit 34. Here, the first luminance, the second luminance, and the third luminance each include the luminance at each position on the light detection unit 34. The processing unit 6 compares the first luminance and the second luminance at each position on the light detection unit 34 and identifies a range where the second luminance is, for example, 80% or more of the first luminance as a detection region R3 ( FIG. 18B ). The processing unit 6 also compares the first luminance with the third luminance at each position on the light detection unit 34 and identifies a range where the third luminance is 80% or more of the first luminance as a detection region R4 ( FIG. 18( c) ) for detecting the secondary light. In this example, the detection region R3 is in the range of 21 mm to 26 mm, and the detection region R4 is in the range of approximately 13 mm to 21 mm. This identification result can be used as the filter data described above. That is, in the above embodiment, the processing unit 6 pre-stored the type of diffracted light (filter data) detected by the light detection unit 34 in each of the first to fourth detection states. However, in the second modified example, the processing unit 6 identifies the regions where the primary light and the secondary light are incident based on the detection results by the light detection unit 34 in the first reference state and the second reference state, and stores the identification result as filter data (step S23).

[0092] Next, the processing unit 6 acquires correction data for correcting luminance for each pixel based on the detection result by the light detection unit 34 in the first reference state and the detection result by the light detection unit 34 in the second reference state (step S24). This correction data is used in step S13 (a step of generating a spectral image).

[0093] In the first, second, and third acquisition steps, the same processing as in the fourth acquisition step is performed with the filters 21 to 23 positioned on the optical path, respectively. That is, in the first acquisition step, filter data for the first filter 21 is acquired, in the second acquisition step, filter data for the second filter 22 is acquired, and in the third acquisition step, filter data for the third filter 23 is acquired.

[0094] In the spectroscopic detection method according to the second modification, the first to fourth acquisition steps described above are performed, followed by steps S11 to S13 of the above embodiment. In step S13, the processing unit 6 determines that the light detected by the light detection unit 34 in step S11 is primary light of the first light L1 and determines that the light detected by the light detection unit 34 in step S12 is secondary light of the second light L2, based on the detection result of the light detection unit 34 in the first reference state and the detection result of the light detection unit 34 in the second reference state. In this example, the processing unit 6 determines that the light detected in step S11 is primary light of the first light L1, based on the identification result (filter data) in step S23 of the first acquisition step. Furthermore, the processing unit 6 determines that the light detected in step S12 is secondary light of the second light L2, based on the identification result (filter data) in step S23 of the second acquisition step.

[0095] In step S13, the processing unit 6 generates a spectral image from the detection result of the primary light of the first light L1 in the first state and the detection result of the secondary light of the second light L2 in the second state based on the above-mentioned determination result. At this time, the processing unit 6 generates the spectral image after correcting the luminance based on the correction data acquired in step S24.

[0096]

[0033] As with the above embodiment, this second modification also enables light in a wide wavelength range to be dispersed and detected with sufficient diffraction efficiency, while ensuring a sufficient dynamic range and wavelength resolution. The spectroscopic measurement system 1 according to the second modification also includes a switching unit 7 disposed upstream of the filter selection unit 4 on the optical path. The switching unit 7 includes a switching filter 41 that transmits the first light L1 and blocks the second light L2. The switching unit 7 is capable of switching between a state in which the switching filter 41 is disposed upstream of the filter selection unit 4 on the optical path and blocks the second light L2, and a state in which the switching filter 41 is not disposed upstream of the filter selection unit 4 on the optical path and both the first light L1 and the second light L2 are incident on the filter selection unit 4. As a result, even if the characteristics of a plurality of selected filters (filters 21 to 24) are not stored in advance, for example, by executing the processes of steps S21 to S24, it becomes possible to determine whether the light detected by the light detection unit 34 using a certain selected filter is primary light of the first light L1 or secondary light of the second light L2. As a result, even if the user does not input the transmission wavelength range for each of the filters 21 to 24 in advance, the above determination becomes possible by acquiring filter data for each of the filters 21 to 24 from the first to fourth acquisition steps.

[0097] The spectroscopic detection method according to the second modification includes steps S21 to S24 before steps S11 to S13. In step S13, the processing unit 6 determines that the light detected by the light detection unit 34 in step S11 is primary light of the first light L1 and determines that the light detected by the light detection unit 34 in step S12 is secondary light of the second light L2 based on the detection result of the light detection unit 34 in the first reference state and the detection result of the light detection unit 34 in the second reference state. In this example, in step S13, the processing unit 6 determines that the light detected in step S11 is primary light of the first light L1 based on the identification result (filter data) in step S23 of the first acquisition step. In addition, the processing unit 6 determines that the light detected in step S12 is secondary light of the second light L2 based on the identification result (filter data) in step S23 of the second acquisition step. This makes it possible to determine whether the light detected by the light detection unit 34 while using the first filter 21 or the second filter 22 is primary light of the first light L1 or secondary light of the second light L2.

[0098] In the second modified example, step S21 is performed before step S22, but step S21 may be performed after step S22.

[0099] If the spectral detection method includes at least the third state step of the above embodiment (e.g., if it includes step S11 and the third state step), in step S13, the processing unit 6 determines that the light detected in the third state step is primary light or secondary light of the third light L3 based on the identification result (filter data) in step S23 of the third acquisition step. In this example, as shown in FIG. 7 , the processing unit 6 determines that light incident at a position between 12 mm and 17.5 mm is primary light of the third light L3, and that light incident at a position between 17.5 mm and 26 mm is secondary light of the third light L3. Then, the processing unit 6 generates a spectral image based on the detection results of the primary light and secondary light of the third light L3 in the third state.

[0100] If the spectral detection method includes at least the fourth state step of the above embodiment (e.g., if it includes step S11 and the fourth state step), in step S13, the processing unit 6 determines that the light detected in the fourth state step is primary light or secondary light of the fourth light L4 based on the identification result (filter data) in step S23 of the fourth acquisition step. In this example, as shown in FIG. 18(b), the processing unit 6 determines that light incident at a position between 21 mm and 26 mm (detection region R3) is primary light of the fourth light L4. Then, as shown in FIG. 18(c), the processing unit 6 determines that light incident at a position between approximately 13 mm and 21 mm (detection region R4) is secondary light of the fourth light L4. Then, the processing unit 6 generates a spectral image based on the detection results of the primary light and secondary light of the fourth light L4 in the fourth state. [Third Modification]

[0101] In a spectroscopic measurement system 1 according to a third modification shown in FIG. 19 , the filter selector 4 constituting the wavelength switching means in the above embodiment is not provided, and the wavelength switching means is constituted by the light irradiator 3. In the third modification, the light irradiator 3 (wavelength switching means) does not include a light source 11, but instead includes a light output unit 51, a mirror 52, a dichroic mirror 53, and a light modulator 54 (light limiting unit). The light output unit 51 outputs first light L1 and second light L2 that are separated from each other. In this example, the first wavelength range of the first light L1 is 800 nm to 1650 nm, and the second wavelength range of the second light L2 is 387.5 nm to 800 nm.

[0102] The first light L1 is reflected by the mirror 52 and the dichroic mirror 53, condensed by the lens 12, and incident on the guide member 13. Meanwhile, the second light L2 is incident on the optical modulator 54. The optical modulator 54 is disposed downstream of the optical output unit 51, and in this example, is disposed between the optical output unit 51 and the lens 12. The optical modulator 54 is, for example, a photoelastic modulator that modulates the polarization state of the incident light at a fixed frequency. By the processing unit 6 controlling the optical modulator 54, the optical modulator 54 can modulate the second light L2 to restrict the downstream progression of the second light L2 and can switch the restriction state of the second light L2. When the optical modulator 54 does not modulate the second light L2, the second light L2 is condensed by the lens 12 and incident on the guide member 13.

[0103] The processing unit 6 controls the optical modulator 54 to alternately switch the detection state of the spectroscopic measurement system 1 between a first state and a second state at high speed. In the third modification, the first state is a state in which the optical modulator 54 restricts the downstream progression of the second light L2. Therefore, in the first state, only the first light L1 is incident on the guide member 13. As in the first modification, the first light L1 incident on the guide member 13 is reflected or scattered by the object B, enters the spectroscope 5, and is dispersed and detected by the spectroscope 5. On the other hand, the second state is a state in which the optical modulator 54 does not restrict the downstream progression of the second light L2. Therefore, in the second state, both the first light L1 and the second light L2 are incident on the guide member 13. As in the first modification, the first light L1 and the second light L2 incident on the guide member 13 are reflected or scattered by the object B, enter the spectroscope 5, and are dispersed and detected by the spectroscope 5. In the third modification, the detection state alternates between the first state and the second state at high speed, so the output of the second light L2 emitted from the optical modulator 54 has a pulse waveform PW1. On the other hand, the first light L1 is not limited by the optical modulator 54, so it is continuously turned on between the first state and the second state. In this way, the wavelength of the light irradiated to the object B differs between the first state and the second state. In the third modification, the light irradiating unit 3 is configured to change the wavelength of the light irradiated to the object B, thereby constituting a wavelength switching means.

[0104] Referring to FIG. 20 , the diffracted light detected by the photodetector 34 in the first and second states will be described. In the first state, only the first light L1 enters the spectroscope 5, and therefore only the primary light of the first light L1 is detected by the photodetector 34. On the other hand, in the second state, both the first light L1 and the second light L2 enter the spectroscope 5. Therefore, both the primary light of the first light L1 and the secondary light of the second light L2 enter the photodetection region 34a (detection region R1). That is, in the second state, the primary light and the secondary light are detected by the photodetector 34 in a state where they overlap in the photodetection region 34a. In FIG. 20 , the wavelength range detected in both the first and second states is indicated as "800 nm to continuous lighting," and the wavelength range detected only in the second state is indicated as "up to 800 nm pulsed lighting."

[0105] A spectroscopic detection method using the spectroscopic measurement system 1 according to the third modification will be described with reference to FIG. 21 . First, in a first state, the primary light of the first light L1 is detected, and in a second state, the primary light of the first light L1 and the secondary light of the second light L2 are detected (step S31). In step S31, the processing unit 6 controls the optical modulator 54 to alternately switch the detection state between the first state and the second state at high speed. In the first state, the second light L2 is limited by the optical modulator 54, while the first light L1 enters the guide member 13, is reflected or scattered by the object B, and enters the spectrometer 5. The first light L1 is split by the spectroscopic unit 32, and the primary light of the first light L1 enters the optical detection region 34a of the optical detection unit 34 and is detected by the optical detection unit 34. In the second state, the second light L2 is not restricted by the optical modulator 54, and therefore both the first light L1 and the second light L2 enter the guide member 13, are reflected or scattered by the object B, and enter the spectroscope 5. Both the first light L1 and the second light L2 are split by the spectroscopic unit 32, and the primary light of the first light L1 and the secondary light of the second light L2 enter the photodetection region 34a of the photodetector 34 and are detected by the photodetector 34.

[0106] Next, the processing unit 6 acquires spectral data of the secondary light of the second light L2 based on the detection results in the first and second states (step S32). As shown in Fig. 22, the detection result in the first state (spectral data D3) indicates the luminance of the primary light of the first light L1, while the detection result in the second state (spectral data D4) indicates the sum of the luminance of the primary light of the first light L1 and the secondary light of the second light L2. In the spectral data D4, the luminance of the primary light is indicated by a dotted line, and the sum of the luminance of the primary light and the secondary light is indicated by a solid line. This sum is the sum of the luminance of the primary light in the wavelength range of 800 nm to 1650 nm and the luminance of the secondary light in the wavelength range of 387.5 nm to 800 nm. Therefore, the processing unit 6 can obtain spectral data of the second light L2 (brightness corresponding to the "second-order diffracted light" in the spectral image E2) by subtracting the spectral data D3 from the spectral data D4. The processing unit 6 generates a spectral image E2 of the first light L1 and the second light L2 based on the obtained spectral data of the second light L2 and the spectral data D3 (step S33).

[0107] As with the above-described embodiment, the third modification also makes it possible to disperse and detect light in a wide wavelength range with sufficient diffraction efficiency, while ensuring a dynamic range and wavelength resolution. Furthermore, in the spectroscopic measurement system 1 according to the third modification, the light irradiating unit 3 is configured to vary the wavelength of the light irradiated onto the object B, and the wavelength switching means is constituted by the light irradiating unit 3. The detection state is switched between the first state and the second state by changing the wavelength of the light irradiated onto the object B from the light irradiating unit 3. This allows the wavelength switching means to be constituted by the light irradiating unit 3 configured to vary the wavelength of the light irradiated onto the object B.

[0108] The light irradiation unit 3 also has an optical output unit 51 that outputs the first light L1 and the second light L2 that are separated from each other, and an optical modulator 54 that is arranged downstream of the optical output unit 51 on the optical path, and the optical modulator 54 is capable of restricting the downstream progression of the second light L2 output from the optical output unit 51 and is capable of switching the restriction state of the second light L2, and the detection state is switched between the first state and the second state by switching the restriction state by the optical modulator 54. As a result, the optical output unit 51 that outputs the first light L1 and the second light L2 that are separated from each other and the optical modulator 54 that is capable of switching the restriction state of the second light L2 can constitute a wavelength switching means.

[0109] Furthermore, in the first state, the optical modulator 54 restricts the second light L2 and allows the first light L1 to travel downstream, and in the second state, the first light L1 and the second light L2 are allowed to travel downstream without restricting them. This allows switching between the first state and the second state by restricting only the second light L2 in the first state without restricting the first light L1 and the second light L2 in the second state. This facilitates the switching operation of the restriction state by the optical modulator 54.

[0110] Furthermore, in the spectroscopic measurement system 1, the detection state is alternately switched between the first state and the second state by switching the limiting state by the optical modulator 54. This makes it possible to perform comprehensive measurements over a wide wavelength range.

[0111] In the third modification, the optical modulator 54 can restrict the downstream progression of the second light L2. However, the optical modulator 54 may also be capable of restricting the downstream progression of the first light L1 and of switching the restriction state of the first light L1. In this case, the first state is a state in which the optical modulator 54 does not restrict the downstream progression of the first light L1, and the second state is a state in which the optical modulator 54 restricts the downstream progression of the first light L1. Therefore, in the first state, both the first light L1 and the second light L2 are incident on the guide member 13, and in the second state, only the second light L2 is incident on the guide member 13. In this case, in step S33, the processing unit 6 subtracts the detection result in the second state from the detection result in the first state to obtain spectral data of the primary light.

[0112] In the third variant, the light irradiation unit 3 has an optical modulator 54 that can limit the downstream progression of the second light L2, but instead of the optical modulator 54, the light irradiation unit 3 may have a chopper or the like that can limit the downstream progression of the second light L2.

[0113] In the third modification, the processing unit 6 controls the optical modulator 54 to alternately switch the detection state between the first state and the second state at high speed, but the processing unit 6 does not need to switch the detection state at high speed. Also, the processing unit 6 does not need to alternately switch the detection state, and may switch the detection state between the first state and the second state once, for example. In the third modification, step S31 is performed before step S32, but step S31 may be performed after step S32. [Fourth Modification]

[0114] 23 does not include the filter selector 4 that constitutes the wavelength switching means in the above embodiment, and the wavelength switching means is constituted by the light irradiator 3. The light irradiator 3 (wavelength switching means) does not include the light source 11, the lens 12, the guide member 13, and the lens 14. The light irradiator 3 includes a pair of first light sources 61, a pair of second light sources 62, a pair of lenses 63, a pair of lenses 64, a pair of lenses 65, and a pair of lenses 66.

[0115] The first light source 61 outputs first light L1 in a first wavelength range (800 nm to 1650 nm or more). The pair of first light sources 61 are arranged on one side and the other side of the irradiation position X1 in the conveying direction A. The first light L1 output from one first light source 61 is collected by one of the pair of lenses 63 and one of the pair of lenses 64, and is irradiated onto the object B at the irradiation position X1 from one side in the conveying direction A (e.g., the upstream side). The first light L1 output from the other first light source 61 is collected by the other of the pair of lenses 63 and the other of the pair of lenses 64, and is irradiated onto the object B at the irradiation position X1 from the other side in the conveying direction A (e.g., the downstream side).

[0116] The second light source 62 outputs second light L2 in a second wavelength range (387.5 nm to 800 nm or less). The pair of second light sources 62 are disposed on one side and the other side of the irradiation position X1 in the conveying direction A. The second light L2 output from one second light source 62 is collected by one of the pair of lenses 65 and one of the pair of lenses 66 and irradiated onto the object B at the irradiation position X1 from one side (e.g., the upstream side) in the conveying direction A. The second light L2 output from the other second light source 62 is collected by the other of the pair of lenses 65 and the other of the pair of lenses 66 and irradiated onto the object B at the irradiation position X1 from the other side (e.g., the downstream side) in the conveying direction A. The first light L1 from the first light source 61 and the second light L2 from the second light source 62 are reflected or scattered by the object B, enter the spectroscope 5, and are separated and detected by the spectroscope 5.

[0117] In the fourth modification, the second light source 62 is pulse-driven to switch between on and off states, and the detection state is alternately switched between the first and second states at high speed. Therefore, the output of the second light L2 has a pulse waveform PW2. In this example, the second light source 62 is an LED (Light Emitting Diode) light source. On the other hand, the first light source 61 is not switched between on and off states and is on in both the first and second detection states. In this example, the first light source 61 is a halogen lamp light source. In this case, costs can be reduced compared to when the first light source 61 is also an LED. The first light source 61 may be an LED light source. In the first state, the first light source 61 is on and the second light source 62 is off. Therefore, in the first state, only the first light L1 is irradiated onto the object B. Furthermore, in the second state, both the first light source 61 and the second light source 62 are on. Therefore, in the second state, both the first light source 61 and the second light source 62 are on. Therefore, in the second state, both the first light source L1 and the second light source L2 are irradiated onto the object B. In this way, the wavelength of the light irradiated onto the object B differs between the first state and the second state. In the fourth modification, the light irradiating unit 3 is configured so that the wavelength of the light irradiated onto the object B is variable, thereby configuring a wavelength switching means.

[0118] The diffracted light detected in the first and second states of the fourth modified example is the same as that of the third modified example shown in Fig. 20. That is, in the first state, the primary light of the first light L1 is detected by the light detection unit 34. In the second state, both the primary light of the first light L1 and the secondary light of the second light L2 are detected by the light detection unit 34.

[0119] The spectroscopic detection method using the spectroscopic measurement system 1 according to the fourth modification is performed in the same manner as the spectroscopic detection method using the spectroscopic measurement system 1 according to the third modification shown in Fig. 21 . First, the second light source 62 is pulse-driven to switch between on and off states, and the detection state is alternately switched between a first state and a second state at high speed. In the first state, the first light source 61 is on and the second light source 62 is off, and the primary light of the first light L1 is detected by the light detection unit 34. In the second state, the first light source 61 is on and the second light source 62 is on, and the primary light of the first light L1 and the secondary light of the second light L2 are detected by the light detection unit 34 (step S31).

[0120] Next, the processing unit 6 acquires spectral data of the secondary light of the second light L2 based on the primary light of the first light L1 detected in step S31 and the primary light of the first light L1 and the secondary light of the second light L2 detected in step S32 (step S32).The processing unit 6 generates a spectral image E2 of the primary light and secondary light based on the acquired spectral data of the secondary light of the second light L2 and the spectral data D3 (FIG. 22) (step S33).

[0121] As in the above embodiment, the fourth modification also enables light in a wide wavelength range to be dispersed and detected with sufficient diffraction efficiency, while ensuring a sufficient dynamic range and wavelength resolution. Furthermore, in the spectroscopic measurement system 1 according to the fourth modification, the light irradiation unit 3 includes a first light source 61 that outputs a first light L1 and a second light source 62 that outputs a second light L2, and the detection state is switched between the first state and the second state by switching the on / off state of the second light source 62. This allows the wavelength switching unit to be configured by the first light source 61 and the second light source 62, at least one of which (in this example, the second light source 62) can be switched between the on / off states.

[0122] In the fourth modified example, in the first state, the first light source 61 is on and the second light source 62 is off, and in the second state, both the first light source 61 and the second light source 62 are on. This makes it possible to switch between the first state and the second state by turning on and off the second light source 62 while keeping the first light source 61 on, thereby facilitating the operation of the first light source 61 and the second light source 62.

[0123] In the fourth modification, the second light source 62 is pulse-driven to switch between on and off states, and the detection state is alternately switched between the first state and the second state, thereby enabling comprehensive measurement over a wide wavelength range.

[0124] In the fourth modified example, the detection state is switched between the first state and the second state by switching the on / off state of the second light source 62, but the detection state may be switched between the first state and the second state by switching the on / off state of the first light source 61. In this case, in the first state, both the first light source 61 and the second light source 62 are on, and in the second state, the first light source 61 is off and the second light source 62 is on. Alternatively, the on / off state may be switched by pulse driving the first light source 61, and the detection state may be alternately switched between the first state and the second state.

[0125] In the fourth modified example, the second light source 62 is pulse-driven to switch between on and off states, and the detection state is alternately switched between the first state and the second state at high speed, but the second light source 62 does not have to be pulse-driven. Furthermore, the second light source 62 does not have to be alternately switched between on and off states, and for example, the second light source 62 may be switched between on and off states once.

[0126] In the fourth modification, the number of first light sources 61 is two and the number of second light sources 62 is two, but the number of first light sources 61 may be any number greater than or equal to one, and the number of second light sources 62 may be any number greater than or equal to one.

[0127] 24 , a chopper 71 may be provided as a light limiting unit instead of the optical modulator 54 of the third modified example. The chopper 71 is disposed downstream of the optical output unit 51, and in this example, is disposed between the optical output unit 51 and the lens 12. The first light L1 and the second light L2 from the optical output unit 51 are incident on the chopper 71.

[0128] The chopper 71 is, for example, a disk-shaped member having a slit 71a. The chopper 71 allows light passing through the slit 71a to travel downstream and restricts light incident on portions other than the slit 71a from traveling downstream. By rotating the chopper 71 using a drive unit (not shown), the chopper 71 alternately restricts the first light L1 and the second light L2. In the fifth modification, the chopper 71 rapidly alternates between a first state in which the first light L1 travels downstream and restricts the second light L2, and a second state in which the chopper 71 restricts the first light L1 and allows the second light L2 to travel downstream. In the first state, only the first light L1 is incident on the guide member 13. In the second state, only the second light L2 is incident on the guide member 13. As in the first modification, the first light L1 and the second light L2 incident on the guide member 13 are reflected or scattered by the object B, enter the spectroscope 5, and are dispersed and detected by the spectroscope 5. In the fifth modification, the detection state alternates between the first state and the second state, so that the outputs of the first light L1 and the second light L2 emitted from the chopper 71 have a pulse waveform PW3. As the chopper 71 alternately limits the first light L1 and the second light L2 in this way, the wavelength of the light irradiated on the object B differs between the first state and the second state. In the fifth modification, the light irradiating unit 3 is configured to change the wavelength of the light irradiated on the object B, thereby constituting a wavelength switching means.

[0129] 25, the diffracted light detected by the photodetector 34 in the first state and the second state will be described. In the first state, only the first light L1 is incident on the spectroscope 5, and therefore only the primary light of the first light L1 is detected by the photodetector 34. On the other hand, in the second state, only the second light L2 is incident on the spectroscope 5, and therefore only the secondary light of the second light L2 is detected by the photodetector 34. In FIG. 25, the wavelength range detected only in the first state is indicated as "800 nm to pulsed lighting," and the wavelength range detected only in the second state is indicated as "up to 800 nm pulsed lighting."

[0130] The spectroscopic detection method using the spectroscopic measurement system 1 according to the fifth modification is performed in the same manner as the spectroscopic detection method using the spectroscopic measurement system 1 according to the above embodiment ( FIG. 11 ). First, the chopper 71 alternately limits the first light L1 and the second light L2, thereby rapidly switching the detection state between a first state and a second state. In the first state, the chopper 71 causes the first light L1 to travel downstream and limits the second light L2, and the primary light of the first light L1 is detected by the photodetector 34 (step S11). In the second state, the chopper 71 limits the first light L1 and causes the second light L2 to travel downstream, and the secondary light of the second light L2 is detected by the photodetector 34 (step S12). Next, the processing unit 6 generates a spectroscopic image based on the primary light of the first light L1 detected in step S11 and the secondary light of the second light L2 detected in step S12 (step S13).

[0131] As with the above-described embodiment, the fifth modification also enables light in a wide wavelength range to be dispersed and detected with sufficient diffraction efficiency, while ensuring a sufficient dynamic range and wavelength resolution. Furthermore, in the spectroscopic measurement system 1 according to the fifth modification, the chopper 71 limits the second light L2 in the first state and allows the first light L1 to travel downstream, and limits the first light L1 in the second state and allows the second light L2 to travel downstream. This allows only one of the first light L1 and the second light L2 to travel downstream in both the first and second states, simplifying the process of generating a spectral image compared to, for example, a case in which both the first light L1 and the second light L2 travel downstream in either the first or second state. In this example, the primary light of the first light L1 and the secondary light of the second light L2 are detected in separate detection states, allowing the spectroscopic measurement system 1 to generate a spectral image without performing step S33 shown in FIG. 21 .

[0132] In the fifth modification, the chopper 71 alternately limits the first light L1 and the second light L2, thereby alternately switching the detection state between the first state and the second state at high speed, but the chopper 71 does not have to alternately switch the detection state at high speed. Furthermore, the chopper 71 does not have to alternately switch the detection state, and may, for example, switch the detection state between the first state and the second state once. In the fifth modification, the light irradiator 3 has the chopper 71 that can alternately limit the first light L1 and the second light L2, but the light irradiator 3 may have, instead of the chopper 71, an optical modulator or the like that can alternately limit the first light L1 and the second light L2. [Sixth Modification]

[0133] In the fourth modified example shown in FIG. 23 , the second light source 62 was pulse-driven. However, in the spectroscopic measurement system 1 according to the sixth modified example shown in FIG. 26 , the first light source 61 and the second light source 62 are each pulse-driven to switch between on and off states. As a result, in the sixth modified example, the detection state is rapidly alternately switched between the first state and the second state. Therefore, the outputs of the first light L1 and the second light L2 have a pulse waveform PW4. In this example, the first light source 61 and the second light source 62 are LED light sources. In the first state, the first light source 61 is on and the second light source 62 is off. Therefore, in the first state, only the first light L1 is irradiated onto the object B. In the second state, the first light source 61 is off and the second light source 62 is on. Therefore, in the second state, only the second light L2 is irradiated onto the object B. In this way, the wavelength of the light irradiated onto the object B differs between the first state and the second state. In the sixth modification, the light irradiating unit 3 is configured so that the wavelength of the light irradiated onto the object B is variable, thereby configuring a wavelength switching means.

[0134] The diffracted light detected in the first and second states of the sixth modified example is the same as that of the fifth modified example shown in Fig. 25. That is, in the first state, the primary light of the first light L1 is detected by the photodetector 34. In the second state, the secondary light of the second light L2 is detected by the photodetector 34.

[0135] The spectroscopic detection method using the spectroscopic measurement system 1 according to the sixth modification is performed in the same manner as the spectroscopic detection method using the spectroscopic measurement system 1 according to the fifth modification. First, the first light source 61 and the second light source 62 are pulse-driven, so that the detection state is alternately switched between a first state and a second state at high speed. In the first state, the first light source 61 is on and the second light source 62 is off, and the primary light of the first light L1 is detected by the light detection unit 34 (step S11). In the second state, the first light source 61 is off and the second light source 62 is on, and the secondary light of the second light L2 is detected by the light detection unit 34 (step S12). Next, the processing unit 6 generates a spectroscopic image based on the primary light of the first light L1 detected in step S11 and the secondary light of the second light L2 detected in step S12 (step S13).

[0136] According to the sixth modification, similarly to the above-described embodiment, light in a wide wavelength range can be dispersed and detected with sufficient diffraction efficiency, and the dynamic range and wavelength resolution can be ensured. Furthermore, in the spectroscopic measurement system 1 according to the sixth modification, in the first state, the first light source 61 is on and the second light source 62 is off, and in the second state, the first light source 61 is off and the second light source 62 is on. This allows only one of the first light source 61 and the second light source 62 to be on in both the first state and the second state, which makes it easier to generate a spectral image than, for example, when switching between the first state and the second state by keeping one of the first light source 61 and the second light source 62 on and turning the other on and off. [Seventh Modification]

[0137] In the sixth modified example shown in Fig. 26 , the first light source 61 and the second light source 62 are each pulse-driven, but in the spectroscopic measurement system 1 according to the seventh modified example shown in Fig. 27 , both the first light source 61 and the second light source 62 are on in both the first state and the second state. Therefore, in both the first state and the second state, both the first light L1 and the second light L2 are irradiated onto the object B. In this way, in the seventh modified example, the on / off states of both the first light source 61 and the second light source 62 cannot be switched.

[0138] The diffracted light detected by the light detection unit 34 in the first state and the second state will be described with reference to Fig. 28. The diffracted light detected in the first state and the second state is the same. Fig. 28 shows an example in which three first light sources 61 output light and three second light sources 62 output light.

[0139] The three first light sources 61 output first light L1 having a wavelength in a first wavelength range (775 nm to 1650 nm). The three first light sources 61 output light having wavelength ranges different from each other. In this example, the three first light sources 61 output light in a fifth portion C5 (approximately 970 nm to approximately 1120 nm), a sixth portion C6 (approximately 1200 nm to approximately 1350 nm), and a seventh portion C7 (approximately 1420 nm to approximately 1600 nm) of the first wavelength range, respectively. The light in the portions C5 to C7 of the first wavelength range is incident on the spectroscopic unit 32, and the primary light of the fifth portion C5, the primary light of the sixth portion C6, and the primary light of the seventh portion C7 are detected by the light detection unit 34.

[0140] The three second light sources 62 output second light L2 having a wavelength in a second wavelength range (387.5 nm to 825 nm). The three second light sources 62 output light having wavelength ranges different from one another. In this example, the three second light sources 62 output light of an eighth portion C8 (approximately 450 nm to approximately 500 nm), a ninth portion C9 (approximately 550 nm to approximately 600 nm), and a tenth portion C10 (approximately 650 nm to approximately 750 nm) of the second wavelength range, respectively. The light of the portions C8 to C10 of the second wavelength range is incident on the spectroscopic unit 32, and the secondary light of the eighth portion C8, the secondary light of the ninth portion C9, and the secondary light of the tenth portion C10 are detected by the light detection unit 34.

[0141] 29, the processing unit 6 generates spectral images of primary light in the fifth portion C5 of the first wavelength range, primary light in the sixth portion C6 of the first wavelength range, primary light in the seventh portion C7 of the first wavelength range, secondary light in the eighth portion C8 of the second wavelength range, secondary light in the ninth portion C9 of the second wavelength range, and secondary light in the tenth portion C10 of the second wavelength range. Note that, if there is an area on the light detection unit 34 where these light beams overlap and are incident, as shown in FIG. 28, the processing unit 6 does not use the luminance in that area as spectral data.

[0142] As described above, the spectroscopic measurement system 1 according to the seventh modification includes the light irradiation unit 3 that irradiates light onto the object B, the spectroscopic unit 32 that disperses the light irradiated from the light irradiation unit 3 and reflected or scattered by the object B, the light detection unit 34 that detects the light dispersed by the spectroscopic unit 32, the light detection unit 34 having sensitivity to a first wavelength range and a second wavelength range shorter than the first wavelength range, and the processing unit 6. The light irradiation unit 3 includes at least one (three in this example) first light source 61 that outputs first light L1 having a wavelength in the first wavelength range, and at least one (three in this example) second light source 62 that outputs second light having a wavelength in the second wavelength range. The first light L1 is incident on the spectroscopic unit 32, and primary light of the first light L1 is detected by the light detection unit 34, and the second light L2 is incident on the spectroscopic unit 32, and secondary light of the second light L2 is detected by the light detection unit 34. The processing unit 6 generates a spectral image based on the primary light of the first light L1 and the secondary light of the second light L2 detected by the light detection unit 34.

[0143] According to the seventh modification, similarly to the above-described embodiment, a spectral image can be generated using the primary light and secondary light, which have relatively high diffraction efficiency. As a result, it is possible to detect light in a wide wavelength range by dispersing it with sufficient diffraction efficiency. In the seventh modification, similarly to the sixth modification, the three first light sources 61 may be pulse-driven to switch between on and off states, and the three second light sources 62 may be pulse-driven to switch between on and off states, thereby alternately switching the detection state between the first state and the second state. That is, in the first state, the three first light sources 61 may be on and the three second light sources 62 may be off, and in the second state, the three first light sources 61 may be off and the three second light sources 62 may be on. The number of first light sources 61 may be any number equal to or greater than one, and the number of second light sources 62 may be any number equal to or greater than one. [Eighth Modification]

[0144] In the spectroscopic measurement system 1 according to the eighth modification shown in FIG. 30 , the light irradiation unit 3 includes a wavelength-tunable light source 81 (wavelength switching means) instead of the light source 11. The wavelength-tunable light source 81 is a light source capable of changing its output wavelength. The wavelength-tunable light source 81 outputs a first light L1 in a first state and a second light L2 in a second state. As a result, in the first state, the primary light of the first light L1 is detected by the photodetector 34, and in the second state, the secondary light of the second light L2 is detected by the photodetector 34. This eighth modification, like the above embodiment, can also disperse and detect light in a wide wavelength range with sufficient diffraction efficiency, while ensuring a sufficient dynamic range and wavelength resolution. Furthermore, in the eighth modification, the wavelength switching means can be configured using the wavelength-tunable light source 81.

[0145] As another modification, in the above embodiment, the spectral images are generated based on the primary light of the first light L1 detected in the first state and the secondary light of the second light L2 detected in the second state. However, the spectral images may be generated based on the detection results in one of the first to fourth detection states. In this case, the processing unit 6 generates the spectral images based on the primary light of the first light L1 detected in the first state. Alternatively, the processing unit 6 generates the spectral images based on the secondary light of the second light L2 detected in the second state. Alternatively, the processing unit 6 generates the spectral images based on the primary light of the first portion C1 of the third light L3 and the secondary light of the second portion C2 of the third light L3 detected in the third state. Alternatively, the processing unit 6 generates the spectral images based on the primary light of the third portion C3 of the fourth light L4 and the secondary light of the fourth portion C4 of the fourth light L4 detected in the fourth state.

[0146] In other words, the spectroscopic measurement system 1 may be a spectroscopic measurement system including "a light irradiation unit 3 that irradiates light onto the object B; a spectroscopic unit 32 that spectrally separates the light irradiated from the light irradiation unit 3 and reflected or scattered by the object B; a light detection unit 34 that detects the light spectrally separated by the spectroscopic unit 32, the light detection unit 34 having sensitivity to a first wavelength range and a second wavelength range shorter than the first wavelength range; and a processing unit 6, wherein third light L3 including a first portion C1 having a wavelength in the first wavelength range and a second portion C2 having a wavelength in the second wavelength range is incident on the spectroscopic unit 32, and primary light of the first portion C1 of the third light L3 and secondary light of the second portion C2 of the third light L3 are detected by the light detection unit 34. The processing unit 6 generates a spectral image based on the primary light of the first portion C1 of the third light L3 and the secondary light of the second portion C2 of the third light L3 detected by the light detection unit 34." This corresponds to the case where the processing unit 6 generates a spectral image based on the primary light of the first portion C1 of the third light L3 and the secondary light of the second portion C2 of the third light L3 detected in the third state.

[0147] Alternatively, the spectroscopic measurement system 1 may be a spectroscopic measurement system including: a light irradiation unit 3 that irradiates light onto the object B; a spectroscopic unit 32 that disperses the light irradiated from the light irradiation unit 3 and reflected or scattered by the object B; a light detection unit 34 that detects the light dispersed by the spectroscopic unit 32, the light detection unit 34 having sensitivity to a first wavelength range and a second wavelength range shorter than the first wavelength range; and a processing unit 6, wherein fourth light L4 including a third portion C3 having a wavelength in the first wavelength range and a fourth portion C4 having a wavelength in the second wavelength range is incident on the spectroscopic unit 32, and primary light of the third portion C3 of the fourth light L4 and secondary light of the fourth portion C4 of the fourth light L4 are detected by the light detection unit 34. The processing unit 6 generates a spectroscopic image based on the primary light of the third portion C3 of the fourth light L4 and the secondary light of the fourth portion C4 of the fourth light L4 detected by the light detection unit 34. This corresponds to the case where the processing unit 6 generates a spectral image based on the primary light of the third portion C3 of the fourth light L4 and the secondary light of the fourth portion C4 of the fourth light L4 detected in the fourth state.

[0148] As with the above embodiment, the spectroscopic measurement system 1 according to these modified examples can generate a spectroscopic image using at least one of the primary light and secondary light, which have relatively high diffraction efficiency, and as a result, it becomes possible to disperse and detect light in a wide wavelength range with sufficient diffraction efficiency.

[0149] The present disclosure is not limited to the above-described embodiments and modifications. For example, the materials and shapes of the components are not limited to those described above, and various materials and shapes can be adopted.

[0150] In the above embodiment and each modified example, the first-order light of the first light L1 and the second-order light of the second light L2 are detected. However, the light detection unit 34 may also detect the N-th order diffracted light (N-th order light) of the first light L1 and the M-th order diffracted light (M-th order light) of the second light L2. Here, N and M are integers other than 0, and the absolute value of N is smaller than the absolute value of M. For example, the light detection unit 34 may detect the second-order light of the first light L1 and the third-order light of the second light L2. That is, N and M are not limited to 1 and 2, but may be 2 and 3. Alternatively, N and M may be −1 and −2. That is, the light detection unit 34 may detect the −1st order light of the first light L1 and the −2nd order light of the second light L2.

[0151] In the above embodiment and each modified example, the diffracted light blocking filter 33 blocks diffracted light other than the second-order light of the second light L2. However, the diffracted light blocking filter 33 may attenuate the diffracted light. However, when the diffracted light blocking filter 33 blocks the diffracted light, the second-order light of the second light L2 can be detected more reliably. The diffracted light blocking filter 33 may attenuate diffracted light other than the first-order light of the first light L1. The spectroscopic measurement system 1 does not have to have the diffracted light blocking filter 33.

[0152] The wavelength range of the illumination light P1 and the first and second wavelength ranges are not limited to the above examples. Furthermore, the sensitivity wavelength range of the light detection unit 34 is not limited to the above examples. In the above embodiment, the light detection unit 34 has a plurality of pixels aligned along a direction corresponding to the spectral direction and a direction perpendicular to the direction. However, the light detection unit 34 may have a plurality of pixels aligned only along the direction corresponding to the spectral direction. In the light detection unit 34, the detection region that detects the primary light of the first light in the first state is common to the detection region that detects the secondary light of the second light in the second state. However, the detection region that detects the primary light may be different from the detection region that detects the secondary light.

[0153] In the above embodiment and each modified example, the first light L1 includes only light in the first wavelength range. However, the first light L1 may further include light in the second wavelength range. Similarly, the second light L2 may include not only light in the second wavelength range but also light in the first wavelength range. Furthermore, the definitions of the first to fourth states in the above embodiment and each modified example are for convenience, and the definitions of the first, second, third, and fourth states are not limited thereto. For example, the third state in the above embodiment may be interpreted as the first state. In this case, the third light L3 described above may be interpreted as the first light, and the first light includes the first portion C1 in the first wavelength range and the second portion C2 in the second wavelength range. Similarly, the fourth state in the above embodiment may be interpreted as the second state. In this case, the fourth light L4 described above may be interpreted as the second light, and the second light includes the third portion C3 in the first wavelength range and the fourth portion C4 in the second wavelength range.

[0154] In the above embodiment and each modified example, the light irradiated from the light irradiation unit 3 and reflected or scattered by the object B is dispersed by the spectroscopic unit 32, but the light irradiated from the light irradiation unit 3 and transmitted through the object B may also be dispersed by the spectroscopic unit 32.

[0155] In the above embodiment and each modified example, the processing unit 6 generates spectral data for the primary light and secondary light from the detection results of the first light L1 and the secondary light of the second light L2, and generates a spectral image based on this spectral data. However, the processing unit 6 may also perform the process up to generating the spectral data for the primary light and secondary light, in which case the processing unit 6 does not need to generate a spectral image.

[0156] 1...spectroscopic measurement system, 3...light irradiation unit (wavelength switching means), 4...filter selection unit (wavelength switching means), 6...processing unit, 7...switching unit, 21...first filter, 22...second filter, 23...third filter, 24...fourth filter, 32...spectrometry unit, 33...diffracted light blocking filter (filter), 34...light detection unit, 34a...light detection region, 41...switching filter, 51...light output unit, 54...light modulator (light limiting unit), 61...first light source, 62...second light source, 71...chopper (light limiting unit), 81...wavelength-tunable light source (wavelength switching means), B...object, C1...first part, C2...second part, C3...third part, C4...fourth part, L1...first light, L2...second light, L3...third light, L4...fourth light.

Claims

1. A spectroscopic measurement system comprising: a light irradiation unit that irradiates light onto an object; a spectroscopic unit that spectroscopically separates the light from the object irradiated by the light irradiation unit; a light detection unit that detects the light dispersed by the spectroscopic unit, the light detection unit having sensitivity to a first wavelength range and a second wavelength range shorter than the first wavelength range; and a processing unit, wherein the system further comprises wavelength switching means that can switch a detection state between a first state in which at least first light having a wavelength in the first wavelength range is incident on the spectroscopic unit and N-th order diffracted light of the first light is detected by the light detection unit, and a second state in which at least second light having a wavelength in the second wavelength range is incident on the spectroscopic unit and M-th order diffracted light of the second light is detected by the light detection unit, wherein N and M are integers other than 0 and the absolute value of N is smaller than the absolute value of M, and the processing unit generates spectroscopic data based on the N-th order diffracted light of the first light detected in the first state and the M-th order diffracted light of the second light detected in the second state.

2. The spectroscopic measurement system according to claim 1, wherein the wavelength switching means is configured by a filter selection unit that places a filter selected from a plurality of selection filters including a first filter that transmits the first light and blocks light other than the first light, and a second filter that transmits the second light and blocks light other than the second light, on the optical path, and wherein in the first state, the first filter is placed on the optical path, and in the second state, the second filter is placed on the optical path.

3. The spectroscopic measurement system according to claim 2, wherein the wavelength switching means is capable of switching the detection state to a third state in which, in addition to the first state and the second state, third light including a first portion having a wavelength in the first wavelength range and a second portion having a wavelength in the second wavelength range is incident on the spectroscopic section, and N-order diffracted light of the first portion of the third light and M-order diffracted light of the second portion of the third light are detected by the light detection section, and the processing section generates the spectroscopic data further based on the N-order diffracted light of the first portion of the third light and the M-order diffracted light of the second portion of the third light detected in the third state.

4. A spectroscopic measurement system as described in claim 2 or 3, further comprising a switching unit arranged on the optical path upstream of the filter selection unit, the switching unit having a switching filter that transmits one of the first light and the second light and blocks light other than the one of the first light and the second light, and is capable of switching between a state in which the switching filter is arranged on the optical path upstream of the filter selection unit and blocks light other than the one of the first light and the second light, and a state in which the switching filter is not arranged on the optical path upstream of the filter selection unit and both the first light and the second light are incident on the filter selection unit.

5. The spectroscopic measurement system according to claim 1, wherein the light irradiating unit is configured so that the wavelength of the light irradiated onto the object is variable, the wavelength switching means is configured by the light irradiating unit, and the detection state is switched between the first state and the second state by changing the wavelength of the light irradiated onto the object from the light irradiating unit.

6. The spectroscopic measurement system according to claim 5, wherein the light irradiation unit has a first light source that outputs the first light and a second light source that outputs the second light, and the detection state is switched between the first state and the second state by switching the on / off state of at least one of the first light source and the second light source.

7. The spectroscopic measurement system of claim 6, wherein in the first state, both the first light source and the second light source are on, and in the second state, the second light source is on and the first light source is off, or in the first state, the first light source is on and the second light source is off, and in the second state, both the first light source and the second light source are on.

8. The spectroscopic measurement system of claim 6, wherein in the first state, the first light source is on and the second light source is off, and in the second state, the first light source is off and the second light source is on.

9. The spectroscopic measurement system according to claim 5, wherein the light irradiation unit has a light output unit that outputs the first light and the second light separated from each other, and a light limiting unit that is arranged downstream of the light output unit on the optical path, wherein the light limiting unit is capable of limiting the downstream progression of at least one of the first light and the second light output from the light output unit and is capable of switching the limiting state of at least one of the first light and the second light, and wherein the detection state is switched between the first state and the second state by the switching of the limiting state by the light limiting unit.

10. The spectroscopic measurement system of claim 9, wherein the light limiting unit limits the second light in the first state and allows the first light to proceed downstream, and in the second state allows the first light and the second light to proceed downstream without restricting them, or wherein the light limiting unit allows the first light and the second light to proceed downstream without restricting them in the first state, and restricts the first light and allows the second light to proceed downstream in the second state.

11. The spectroscopic measurement system according to claim 9, wherein the light limiting unit limits the second light and causes the first light to travel downstream in the first state, and limits the first light and causes the second light to travel downstream in the second state.

12. A spectroscopic measurement system according to any one of claims 1 to 11, further comprising a filter disposed between the spectroscopic unit and the light detection unit, which attenuates at least one of diffracted light other than the N-th order diffracted light of the first light and diffracted light other than the M-th order diffracted light of the second light.

13. A spectroscopic measurement system according to any one of claims 1 to 12, wherein the absolute value of N is 1 and the absolute value of M is 2.

14. A spectroscopic measurement system according to any one of claims 1 to 13, wherein the spectroscopic unit includes a spectroscopic element capable of separating light in a wavelength range of at least 1000 nm to 1500 nm into first-order diffracted light.

15. A spectroscopic measurement system according to any one of claims 1 to 14, wherein the detection area of ​​the photodetector that detects the Nth-order diffracted light of the first light in the first state is common to the detection area of ​​the photodetector that detects the Mth-order diffracted light of the second light in the second state.

Images