DETECTION APPARATUS AND DETECTION METHOD

Abstract

A detection device (100) comprises: a light source (1); a splitting optical system (4) for splitting light that has been emitted from the light source (1) and has passed through a detection area into deflected light that is light that has been deflected as a result of refractive index variation at a detection area and non-deflected light that is light that has not been deflected as a result of the refractive index variation; an imaging unit (5) for imaging at least some of the non-deflected light and / or at least some of the deflected light and acquiring a brightness image indicating refractive index variation at the detection area; and a first dispersion unit (6) for dispersing at least some of the deflected light and acquiring first spectral characteristic information indicating a spectral characteristic of the deflected light.

Description

[Technical field]

[0001] The present disclosure relates to a detection device and a detection method. [Background technology]

[0002] The Schlieren method is known for visualizing refractive index changes in a medium. For example, Patent Document 1 shows a configuration that includes a light source, a lens that collects light emitted from the light source and passed through a measurement section to form an image on a screen, and a knife edge that blocks part of the light between the lens and the screen, and when a density change occurs in the medium gas in the measurement section, the light refraction effect causes the light and dark to be observed as an image on the screen. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 3993071 Summary of the Invention [Problem to be solved by the invention]

[0004] However, while conventional Schlieren techniques can visualize refractive index changes in a medium, they do not provide information about the type of material that caused the refractive index change.

[0005] The present disclosure aims to provide a detection device and a detection method that can obtain not only a brightness image showing a refractive index change in a detection area, but also information regarding the type of substance that caused the refractive index change. [Means for solving the problem]

[0006] This disclosure One aspect ofThe detection device according to the present invention includes a light source; a separation optical system that separates, from light emitted from the light source and passing through a predetermined detection region, polarized light, which is light deflected by a refractive index change in the detection region, and non-polarized light, which is light not deflected by the refractive index change; an imaging unit that images at least one of at least a portion of the non-polarized light and at least a portion of the polarized light to obtain a luminance image indicative of the refractive index change in the detection region; and a first spectroscopic unit that disperses at least a portion of the polarized light to obtain first spectral characteristic information indicative of the spectral characteristics of the polarized light. and a focusing optical system that focuses light emitted from the light source so that the unpolarized light is focused at a focusing point, the separation optical system separates the polarized light and the unpolarized light from the light that has passed through the detection area and been focused by the focusing optical system, the separation optical system including a partially reflecting mirror element having a transmitting portion that transmits light and a reflecting portion that is located around the transmitting portion and has a reflecting surface that reflects light, the partially reflecting mirror element being disposed such that the transmitting portion is located near the focusing point and the reflecting surface is inclined with respect to the optical axis of the focusing optical system, the unpolarized light is transmitted through the transmitting portion and travels along a first optical path, and the polarized light is reflected by the reflecting surface and travels along a second optical path different from the first optical path. do. A detection device according to another aspect of the present disclosure includes a light source; a separation optical system that separates, from light emitted from the light source and passing through a predetermined detection region, polarized light, which is light deflected by a refractive index change in the detection region, and unpolarized light, which is light not deflected by the refractive index change; an imaging unit that images at least one of at least a portion of the unpolarized light and at least a portion of the polarized light to obtain a luminance image indicative of the refractive index change in the detection region; a first spectroscopic unit that spectroscopically separates at least a portion of the polarized light to obtain first spectral characteristic information indicative of the spectral characteristics of the polarized light; and a focusing unit that focuses the unpolarized light at a focusing point. and a focusing optical system that focuses light emitted from the light source, the separation optical system separating the polarized light and the non-polarized light from the light that has passed through the detection area and been focused by the focusing optical system, the separation optical system including a partially reflective mirror element having a reflecting portion having a reflective surface that reflects light and a transmitting portion located around the reflecting portion and transmitting light, the partially reflective mirror element being arranged such that the reflecting surface is located near the focusing point and is inclined with respect to the optical axis of the focusing optical system, the non-polarized light is reflected by the reflecting surface and travels along a first optical path, and the polarized light is transmitted through the transmitting portion and travels along a second optical path different from the first optical path. A detection device according to still another aspect of the present disclosure includes a light source; a separation optical system that separates, from light emitted from the light source and passing through a predetermined detection region, polarized light that is light deflected by a refractive index change in the detection region and unpolarized light that is light not deflected by the refractive index change; an imaging unit that images at least one of at least a portion of the unpolarized light and at least a portion of the polarized light to obtain a luminance image showing the refractive index change in the detection region; a first spectroscopic unit that disperses at least a portion of the polarized light to obtain first spectral characteristic information showing the spectral characteristics of the polarized light; and a focusing optical system that focuses the light emitted from the light source such that the unpolarized light is focused at a focusing point, the separation optical system focusing the light that passes through the detection region and is focused by the focusing optical system. The separation optical system separates the polarized light and the non-polarized light from the incident light, and includes a partially reflective mirror element having a transparent portion that transmits light, a first reflective portion located on the periphery of the transparent portion and having a first reflective surface that reflects light, and a second reflective portion located on the periphery of the transparent portion and having a second reflective surface that reflects light, wherein the partially reflective mirror element is positioned near the focusing point and is inclined with respect to the optical axis of the focusing optical system so that the first and second reflective surfaces face in different directions, and the non-polarized light is transmitted through the transparent portion and travels along a first optical path, a portion of the polarized light is reflected by the first reflective surface and travels along a second optical path different from the first optical path, and another portion of the polarized light is reflected by the second reflective surface and travels along a third optical path different from the first and second optical paths. A detection device according to still another aspect of the present disclosure includes a light source; a separation optical system that separates, from light emitted from the light source and passing through a predetermined detection region, polarized light that is light deflected by a refractive index change in the detection region and unpolarized light that is light not deflected by the refractive index change; an imaging unit that images at least one of at least a portion of the unpolarized light and at least a portion of the polarized light to obtain a luminance image showing the refractive index change in the detection region; a first spectroscopic unit that disperses at least a portion of the polarized light to obtain first spectral characteristic information showing the spectral characteristics of the polarized light; and a focusing optical system that focuses the light emitted from the light source such that the unpolarized light is focused at a focusing point, the separation optical system being configured to focus the light that passes through the detection region and is deflected by the focusing optical system. and a separating optical system for separating the polarized light from the non-polarized light, the separating optical system including a first reflecting section having a first reflecting surface that reflects light, a transmitting section located around the first reflecting section and transmitting light, and a second reflecting section located around the first reflecting section and having a second reflecting surface that reflects light, the first reflecting surface of the partially reflecting mirror element being located around the light-collecting point, the first and second reflecting surfaces being inclined with respect to an optical axis of the collecting optical system, the non-polarized light being reflected by the first reflecting surface and traveling along a first optical path, a portion of the polarized light being transmitted through the transmitting section and traveling along a second optical path different from the first optical path, and another portion of the polarized light being reflected by the second reflecting surface and traveling along a third optical path different from the first and second optical paths.

[0007] This disclosure One aspect of The detection method according to the present invention includes separating, from light emitted from a light source and passing through a predetermined detection area, polarized light that is light deflected by a change in refractive index in the detection area and unpolarized light that is light that is not deflected by the change in refractive index, and capturing an image of at least one of at least a portion of the unpolarized light and at least a portion of the polarized light to obtain a luminance image showing the change in refractive index in the detection area. And, before and obtaining first spectral characteristic information indicating a spectral characteristic of the polarized light by dispersing at least a portion of the polarized light. and focusing the light emitted from the light source using a focusing optical system so that the unpolarized light is focused at a focusing point, the separating includes separating the polarized light and the unpolarized light from the light that passes through the detection area and is focused, the separating includes separating using a partially reflective mirror element having a transmissive portion that transmits light and a reflective portion located around the transmissive portion and having a reflective surface that reflects light, the partially reflective mirror element being positioned such that the transmissive portion is located near the focusing point and the reflective surface is inclined with respect to the optical axis of the focusing optical system, the unpolarized light is transmitted through the transmissive portion and travels along a first optical path, and the polarized light is reflected by the reflective surface and travels along a second optical path different from the first optical path. Effect of the Invention

[0008] According to the present disclosure, it is possible to provide a detection device and a detection method that can obtain not only a brightness image showing the refractive index change in the detection area, but also information regarding the type of substance that caused the refractive index change. [Brief description of the drawings]

[0009] [Figure 1] FIG. 1 is a schematic diagram showing a detection device according to a first embodiment. [Diagram 2] FIG. 2 is a schematic perspective view showing an example of a separation element in the first embodiment. [Diagram 3] FIG. 2 is a diagram for explaining an example of estimation by an estimation unit in the first embodiment. [Figure 4] FIG. 4 is a diagram for explaining an example of a process performed by an output unit in the first embodiment. [Diagram 5] FIG. 4 is a schematic diagram showing a detection device according to a modified example of the first embodiment. [Figure 6] FIG. 11 is a schematic perspective view showing an example of a separation element in a modified example of the first embodiment. [Figure 7] FIG. 11 is a schematic diagram showing a detection device according to a second embodiment. [Figure 8] FIG. 11 is a schematic perspective view showing an example of a separation element in the second embodiment. [Figure 9] FIG. 11 is a schematic diagram showing a detection device according to a third embodiment. [Figure 10] 13(A) and 13(B) are diagrams for explaining an example of estimation by an estimation unit in the third embodiment. [Figure 11] FIG. 13 is a schematic diagram showing a detection device according to a modified example of the third embodiment. [Figure 12] FIG. 11 is a schematic diagram showing a detection device according to a fourth embodiment. [Figure 13] FIG. 13 is a schematic diagram showing a detection device according to a first modified example of the fourth embodiment. [Figure 14] FIG. 13 is a schematic perspective view showing an example of a separation element in a first modification of the fourth embodiment. [Figure 15] FIG. 13 is a schematic perspective view showing another example of the separation element in the first modification of the fourth embodiment. [Figure 16] FIG. 13 is a schematic diagram showing a detection device according to a second modification of the fourth embodiment. [Figure 17] FIG. 13 is a schematic diagram showing a detection device according to a third modification of the fourth embodiment. [Figure 18] 13(A) and 13(B) are schematic perspective views showing an example of a second separation element in a third modification of the fourth embodiment. [Figure 19] FIG. 13 is a schematic diagram showing a detection device according to embodiment 5. [Figure 20]FIG. 13 is a schematic perspective view showing an example of a separation element in embodiment 5. [Figure 21] FIG. 13 is a schematic diagram showing a detection device according to a sixth embodiment. [Figure 22] 13 is a schematic diagram showing an example of the configuration of a spectroscopic section (spectroscopic camera) in the sixth embodiment. FIG. [Diagram 23] 23 is a schematic diagram showing central wavelengths of four types of wavelength filters of a spectroscopic section (spectroscopic camera) in the sixth embodiment. FIG. [Figure 24] 1 is a block diagram showing an example of a hardware configuration of a detection device according to a first embodiment. [Diagram 25] 1 is a block diagram showing an example of a hardware configuration of a detection device according to a first embodiment. [Figure 26] 13(A) to 13(C) are diagrams showing modified examples of the optical system up to the separation optical system in the detection device according to the first embodiment. [Figure 27] 1A to 1C are diagrams for explaining various configurations of a separation optical system. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] Hereinafter, an embodiment will be described with reference to the drawings. Embodiment 1 Fig. 1 is a schematic diagram showing a detection device 100 according to embodiment 1. The detection device 100 according to embodiment 1 will be described below with reference to Fig. 1. The detection method will also become clear from the following description.

[0011] The detection device 100 is a device that performs detection (or analysis) on a predetermined detection region R. The detection region R is a region of a medium (or a transparent medium) M that transmits light, or a region filled with the medium M. A refractive index change (or a refractive index gradient) may occur in the detection region R. The refractive index change is a spatial change in the refractive index. The detection device 100 acquires a luminance image showing the refractive index change in the detection region R, and acquires information on the type of substance that has caused the refractive index change. Hereinafter, the substance that has caused the refractive index change is called a "detection target A." FIG. 1 shows the detection target A in a schematic manner. The detection target A is, for example, a type of substance different from the medium M. In this case, the detection target A may flow into or be placed in the detection region R. In one example, the medium M is air, and the detection target A is a gas different from air. However, the medium M and the detection target A are not limited to these, and may be any of a solid, a liquid, and a gas.

[0012] 1, the detection device 100 includes a light source 1, a separation optical system 4, an imaging unit 5, and a spectroscopic unit 6. The detection device 100 may also include an irradiation optical system 2, a light collection optical system 3, an estimation unit 7, an output unit 8, and a display unit 9.

[0013] The light source 1 emits an output light L1. The light source 1 has, for example, a spectral distribution suitable for the application of the detection device 100. As the light source 1, various light sources such as a halogen lamp, a xenon lamp, or a light emitting diode can be used.

[0014] The irradiation optical system (or collimation optical system) 2 collimates the emission light L1 emitted from the light source 1, and irradiates the detection region R with the collimated light as illumination light L2. The irradiation optical system 2 is, for example, a lens that converts the emission light L1 into illumination light L2, which is substantially parallel light.

[0015] The light collecting optical system 3 collects light emitted from the light source 1 (in the example of FIG. 1, light emitted from the light source 1 and passing through the detection region R) and emits the collected light as collected light L3. The light collecting optical system 3 is, for example, a lens that collects light that has passed through the detection region R out of the illumination light L2 and converts it into collected light L3. The detection region R is provided between the irradiation optical system 2 and the light collecting optical system 3.

[0016] The light that has passed through the detection region R (collected light L3 emitted from the collecting optical system 3 in the example of FIG. 1) includes light that has been deflected by the refractive index change in the detection region R and light that has not been deflected by the refractive index change. For example, among the light that passes through the detection region R, light that passes through the detection target A is deflected by the refractive index change, and light that does not pass through the detection target A is not deflected. Hereinafter, light that has been deflected by the refractive index change in the detection region R is referred to as deflected light, and light that has not been deflected by the refractive index change is referred to as non-polarized light. Deflected light is light whose traveling direction has changed due to the refractive index change, and non-polarized light is light whose traveling direction has not changed. Note that if there is no refractive index change in the detection region R (or if the detection target A does not exist), the collected light L3 emitted from the collecting optical system 3 does not include deflected light.

[0017] The focusing optical system 3 focuses the light emitted from the light source 1 (in the example of FIG. 1, the light emitted from the light source 1 and passing through the detection region R) so that the unpolarized light is focused at a focusing point. The focusing optical system 3 is configured so that the light that has passed through the detection region R is focused at a focusing point when there is no change in the refractive index in the detection region R. Hereinafter, the focusing point of the unpolarized light is referred to as the focusing point of the focusing optical system 3. In the example of FIG. 1, the focusing point of the focusing optical system 3 coincides or approximately coincides with the focus of the focusing optical system 3.

[0018] The separation optical system (or branching optical system) 4 separates (or branches) the light that has passed through the detection region R into a polarized light L4 and a non-polarized light L5. In the example of FIG. 1, the separation optical system 4 separates the collected light L3, which is light that has passed through the detection region R and has been collected by the collecting optical system 3, into a polarized light L4 and a non-polarized light L5. The separation optical system 4 also includes a separation element 10 that is disposed near the collecting point (or focal point) of the collecting optical system 3 and separates the polarized light L4 and the non-polarized light L5 of the collected light L3. The separation element 10 transmits the non-polarized light L5 and reflects the polarized light L4. The separation element 10 is, for example, a partially reflecting mirror element described later. The polarized light L4 separated by the separation optical system 4 may be all or a part of the polarized light included in the collected light L3, and the non-polarized light L5 separated by the separation optical system 4 may be all or a part of the non-polarized light included in the collected light L3.

[0019] The imaging unit 5 captures the unpolarized light L5 separated by the separation optical system 4, and obtains and outputs a luminance image Im1 showing the refractive index change (or refractive index distribution) in the detection region R. The luminance image Im1 is, for example, image data showing the luminance values ​​of a plurality of pixels. The luminance image Im1 is, for example, luminance distribution information showing the luminance distribution of the unpolarized light L5. The luminance image Im1 is, for example, an image in which the refractive index change in the detection region R is expressed as a difference between light and dark (or contrast). For example, the light captured by the imaging unit 5 does not include the deflected light deflected by the detection target A, so the luminance image Im1 is an image in which the luminance value of the image region corresponding to the region where the detection target A exists is smaller than the luminance value of the other image regions (or an image in which the image region corresponding to the region where the detection target A exists is darker than the surroundings). The luminance image Im1 is, for example, similar to an image that visualizes the refractive index change obtained by the conventional Schlieren method. As the imaging unit 5, various cameras such as a CCD camera can be used. The imaging unit 5 may be provided with an imaging optical system that adjusts the focal length in addition to the camera.

[0020] The spectroscopic unit 6 separates the polarized light L4 separated by the separation optical system 4, and acquires and outputs spectroscopic characteristic information Is1 indicating the spectroscopic characteristics (or wavelength characteristics) of the polarized light. That is, the spectroscopic unit 6 detects the spectroscopic characteristics of the polarized light. The spectroscopic unit 6 detects, for example, the intensities of multiple wavelength components of the polarized light L4, and outputs information indicating the intensity of each wavelength component as the spectroscopic characteristic information Is1. The spectroscopic unit 6 can be any of various spectrometers, such as a grating spectrometer or a prism spectrometer.

[0021] The deflected light is light deflected by the object A, and has spectral characteristics reflecting the inherent spectral characteristics of the object A. Here, the spectral characteristics of the object A include the spectral transmittance characteristics, the spectral absorption characteristics, and the spectral reflectance characteristics. Therefore, the spectral characteristic information Is1 can be said to be information on the type of the object A, information indicating the type of the object A, or information for estimating the type of the object A.

[0022] The estimation unit 7 estimates the type of the detection target A from the spectroscopic characteristic information Is1 acquired by the spectroscopic unit 6, and outputs type information It1 indicating the estimated type. The estimation unit 7 estimates the type of the detection target A by using the spectral characteristics of the detection target A included in the spectral characteristics of the polarized light indicated by the spectral characteristic information Is1.

[0023] In a first example, the estimation unit 7 determines the type of the detection target A by comparing the spectral characteristics of the polarized light when the candidate substance is present in the detection region R with the spectral characteristics indicated by the spectral characteristic information Is1 for each of one or more types of candidate substances. For example, the estimation unit 7 calculates the degree of agreement between the spectral characteristics of the polarized light when a candidate substance is present in the detection region R and the spectral characteristics indicated by the spectral characteristic information Is1, and determines the type of the candidate substance as the type of the detection target A if the degree of agreement is higher than a predetermined threshold. In addition, for example, the estimation unit 7 calculates the degree of agreement between the spectral characteristics of the polarized light when the candidate substance is present in the detection region R and the spectral characteristics indicated by the spectral characteristic information Is1 for each of multiple types of candidate substances, and determines the type of the candidate substance with the highest degree of agreement as the type of the detection target A. Here, the spectral characteristics of the polarized light when the candidate substance is present in the detection region R are obtained in advance by an experiment or the like and stored in the detection device 100 or the like.

[0024] In the first example, the estimation unit 7 may detect a characteristic wavelength range from the spectral characteristics indicated by the spectral characteristic information Is1 and compare the spectral characteristics in the characteristic wavelength range. Here, the characteristic wavelength range is, for example, a wavelength range in which a feature (e.g., a peak) not present in a predetermined reference spectral characteristic appears among the spectral characteristics indicated by the spectral characteristic information Is1. The reference spectral characteristic is, for example, the spectral characteristic of the collected light L3 when the detection region R includes only the medium M, and is obtained in advance by an experiment or the like and stored in the detection device 100 or the like.

[0025] In the second example, the estimation unit 7 detects a characteristic wavelength range from the spectral characteristics indicated by the spectral characteristic information Is1. Here, the characteristic wavelength range is the same as described above. Then, the estimation unit 7 compares the detected characteristic wavelength range with the characteristic wavelength ranges of one or more types of candidate substances to determine the type of the detection target A. In this case, the estimation unit 7 can determine the type of the detection target A by calculating the degree of agreement, as in the first example. The characteristic wavelength range of each candidate substance is, for example, a wavelength range in which a feature (e.g., a peak) not present in a predetermined reference spectral characteristic appears among the spectral characteristics of polarized light when the candidate substance is present in the detection region R, and is obtained in advance by an experiment or the like and stored in the detection device 100 or the like. Here, the reference spectral characteristic is the same as described above.

[0026] The output unit 8 outputs the detection result Ir1 including information on the refractive index distribution of the detection region R based on the luminance image Im1 acquired by the imaging unit 5 and information on the type of the detection target A based on the spectral characteristic information Is1 acquired by the spectroscopic unit 6. The information on the refractive index distribution of the detection region R includes the luminance image Im1 and information obtained from the luminance image Im1. The information obtained from the luminance image Im1 includes the position, size, and time changes of the detection target A. The information on the type of the detection target A includes the spectral characteristic information Is1 and information obtained from the spectral characteristic information Is1. The information obtained from the spectral characteristic information Is1 includes type information It1 indicating the type of the detection target A estimated by the estimation unit 7. The output unit 8, for example, displays the detection result Ir1 on the display unit (or monitor) 9. In this case, the output unit 8 may display the information on the refractive index distribution of the detection region R and the information on the type of the detection target A in a combined form or separately. In one example, the output unit 8 causes the display unit 9 to display an output image (or a visualized image of the detection target A) in which type information It1 is added to the luminance image Im1 as the detection result Ir1. However, the output unit 8 does not necessarily need to display the detection result Ir1, and may store the detection result Ir1 in a storage medium.

[0027] 2 is a schematic perspective view showing an example of the separation element 10. Hereinafter, an example of the separation element 10 will be described with reference to FIGS.

[0028] 2, separation element 10 is a partial reflection mirror element that reflects a part of the incident light. Separation element 10 transmits unpolarized light distributed near the optical axis of focusing optical system 3 out of collected light L3 emitted from focusing optical system 3, and reflects polarized light distributed outside the vicinity of the optical axis. Separation element 10 is, for example, a pinhole mirror having a pinhole, which is a minute hole, in the center for transmitting unpolarized light, and a reflective surface around the center for reflecting polarized light.

[0029] The separation element 10 has a transmission part (or transmission region) 21 that transmits light, and a reflection part 22 located around the transmission part 21 and having a reflection surface (or reflection region) 22a that reflects light. The separation element 10 is disposed such that the transmission part 21 is located near the light collection point (or focus) of the light collection optical system 3, the reflection surface 22a is inclined with respect to the optical axis of the light collection optical system 3, the non-polarized light L5 passes through the transmission part 21 and travels along a first optical path, and the polarized light L4 is reflected by the reflection surface 22a and travels along a second optical path different from the first optical path. The non-polarized light L5 that passes through the transmission part 21 enters the imaging unit 5, and the polarized light L4 that is reflected by the reflection surface 22a enters the spectroscopic unit 6.

[0030] In the example of Fig. 2, the transmitting portion 21 is a central portion located at the center of the separation element 10, and the reflecting portion 22 is a peripheral portion located around the central portion. The size of the transmitting portion 21 is approximately the same as or slightly smaller than the size of the focused spot of the focused light L3 when there is no refractive index change (or no detection target A). In Fig. 2, the transmitting portion 21 is circular and has a diameter approximately the same as or slightly smaller than the diameter of the focused spot. However, the shape of the transmitting portion 21 may be other shapes.

[0031] The reflecting surface 22a is, for example, a metal film or a dielectric film having a high reflectance formed by vapor deposition. In addition, it is desirable that the reflecting surface 22a is disposed on the side of the reflecting section 22 on which the collected light L3 is incident. This is because, for example, in a configuration in which the reflecting section 22 has a base material and a reflecting surface 22a and the collected light L3 passes through the base material and is reflected by the reflecting surface 22a, good reflection is hindered due to light scattering within the base material. The same applies to the other reflecting surfaces described later.

[0032] Fig. 3 is a diagram for explaining an example of the estimation by the estimation unit 7. Hereinafter, with reference to Fig. 3, an example of the estimation by the estimation unit 7 will be described.

[0033] 3 shows the spectral characteristic 31 of the polarized light indicated by the spectral characteristic information Is1 acquired by the spectroscopic section 6. The spectral characteristic 31 indicates the intensity of the polarized light for each wavelength.

[0034] The estimation unit 7 detects a characteristic wavelength range 32 from the spectroscopic characteristic 31. In FIG. 3, the characteristic wavelength range 32 is a wavelength range from wavelength λ1 to wavelength λ2 (>λ1). For example, the intensity of the polarized light is reduced near a specific wavelength range between wavelengths λ1 and λ2 due to light absorption by the detection target A. Then, the estimation unit 7 compares the spectroscopic characteristic 31 with the inherent spectroscopic characteristic of a specific gas in the characteristic wavelength range 32 to determine whether the detection target A is the specific gas. The inherent spectroscopic characteristic of a specific gas is, for example, the spectroscopic characteristic of the polarized light when the gas is present in the detection region R, and is obtained in advance by an experiment or the like and stored in the detection device 100 or the like.

[0035] 4 is a diagram for explaining an example of a process performed by the output unit 8. Hereinafter, an example of a process performed by the output unit 8 will be described with reference to FIG.

[0036] The output unit 8 generates an output image (or visualized image) 41 by adding the type information It1 to the luminance image Im1, and causes the display unit 9 to display the output image 41 as the detection result Ir1. In FIG. 4, the luminance image Im1 has an image area 42 that is darker than the surroundings and corresponds to the area where the detection target A exists. The output image 41 has an image area 43 that corresponds to the area where the detection target A exists. In the output image 41, the image area 43 is associated with the type of substance indicated by the type information It1. The image area 43 may be drawn in a color, color scheme, pattern, etc. that corresponds to the type of substance indicated by the type information It1, or may be provided with a symbol, character, etc. that corresponds to the type of substance.

[0037] According to the above-described first embodiment, the following effects can be obtained.

[0038] The detection device 100 includes a light source 1, a separation optical system 4 that separates, among the light emitted from the light source 1 and passing through the detection region R, polarized light L4, which is light deflected by a refractive index change in the detection region R, and unpolarized light L5, which is light not deflected by the refractive index change, an imaging unit 5 that captures the unpolarized light L5 to obtain a luminance image Im1 that shows the refractive index change in the detection region R, and a spectroscopic unit 6 that disperses the polarized light L4 to obtain spectral characteristic information Is1 that shows the spectral characteristics of the polarized light. With this configuration, it is possible to obtain information on the type of material that has caused the refractive index change, together with the luminance image that shows the refractive index change in the detection region R. In addition, it is possible to estimate the type of material that has caused the refractive index change from the spectral characteristic information Is1.

[0039] Detection device 100 further includes a focusing optical system 3 that focuses the light emitted from light source 1 so that the unpolarized light is focused at a focusing point, and a separation optical system 4 separates polarized light L4 and unpolarized light L5 from the light that has passed through detection region R and been focused by focusing optical system 3. This configuration makes it easy to separate polarized light L4 and unpolarized light L5, enabling the device to be made more compact.

[0040] The separation optical system 4 includes a partially reflecting mirror element having a transmitting portion 21 that transmits light and a reflecting portion 22 that is located around the transmitting portion 21 and has a reflecting surface 22a that reflects light. The partially reflecting mirror element is arranged such that the transmitting portion 21 is located near the focusing point of the focusing optical system 3, the reflecting surface 22a is inclined with respect to the optical axis of the focusing optical system 3, the unpolarized light L5 passes through the transmitting portion 21 and travels along a first optical path, and the polarized light L4 is reflected by the reflecting surface 22a and travels along a second optical path different from the first optical path. With this configuration, the optical path (or traveling direction) of the unpolarized light L5 and the optical path (or traveling direction) of the polarized light L4 can be separated. This makes it possible to detect the luminance image Im1 and the spectral characteristic information Is1 with high sensitivity even when the refractive index change is minute. Specifically, when the change in the refractive index is small, the change in the direction of light travel due to the change in the refractive index is also small, and the positional deviation of the polarized light relative to the non-polarized light after focusing (specifically, the positional deviation between the focusing position of the non-polarized light and the focusing position of the polarized light appearing on the focusing surface) is also small. On the other hand, the size of each of the imaging device and the spectroscopic device used as the imaging unit 5 and the spectroscopic device is usually several centimeters or more, which is very large compared to the positional deviation of the focusing position. Therefore, unless the optical path of the non-polarized light and the optical path of the polarized light are separated, it is difficult to arrange the imaging device and the spectroscopic device, and it is very difficult to use a high-sensitivity imaging device and a spectroscopic device that are relatively large in size. According to the above configuration of the present embodiment, by setting the size of the transmission part 21 to an appropriate size (for example, a size approximately equal to or slightly smaller than the size of the focusing spot), the transmission part (for example, a pinhole) 21 and the reflection surface 22a around it can largely separate the optical path of the non-polarized light from the optical path of the polarized light due to the small positional deviation between the focusing position of the non-polarized light and the focusing position of the polarized light. This makes it easier to arrange the imaging device and the spectroscopic device, and enables the use of a relatively large, highly sensitive imaging device and spectroscopic device.

[0041] <Modification> 5 is a schematic diagram showing a detection device 100A according to a modification of embodiment 1. Hereinafter, the detection device 100A according to the modification of embodiment 1 will be described with reference to FIG.

[0042] The detection device 100A includes a separation element 51 instead of the separation element 10 in Fig. 1. The separation element 51 reflects unpolarized light L5 and transmits polarized light L4.

[0043] 6 is a schematic perspective view showing an example of the separation element 51. Hereinafter, an example of the separation element 51 will be described with reference to FIGS.

[0044] The separation element 51 is a partially reflecting mirror element. The separation element 51 reflects non-polarized light distributed near the optical axis of the focusing optical system 3 out of the focusing light L3 emitted from the focusing optical system 3, and transmits polarized light distributed outside the vicinity of the optical axis.

[0045] The separation element 51 has a reflecting section 61 having a reflecting surface (or reflecting region) 61a that reflects light, and a transmitting section (or transmitting region) 62 that is located around the reflecting section 61 and transmits light. The separation element 51 is disposed such that the reflecting surface 61a is located near the focusing point (or focal point) of the focusing optical system 3 and is inclined with respect to the optical axis of the focusing optical system 3, and the unpolarized light L5 is reflected by the reflecting surface 61a and travels along a first optical path, and the polarized light L4 is transmitted through the transmitting section 62 and travels along a second optical path different from the first optical path. The unpolarized light L5 reflected by the reflecting surface 61a enters the imaging section 5, and the polarized light L4 transmitted through the transmitting section 62 enters the spectroscopic section 6.

[0046] In the example of Fig. 6, the reflecting portion 61 is a central portion located at the center of the separation element 51, and the transmitting portion 62 is a peripheral portion located around the central portion. The size of the reflecting surface 61a is approximately the same as or slightly smaller than the size of the focused spot of the focused light L3 when there is no refractive index change (or no detection target A). In Fig. 6, the reflecting surface 61a is circular and has a diameter approximately the same as or slightly smaller than the diameter of the focused spot. However, the shape of the reflecting surface 61a may be other shapes.

[0047] The transmission portion 62 is a portion that transmits light, and is made of, for example, a transparent material. The separation element 51 is formed, for example, by forming a reflective surface in the center of a transparent base material.

[0048] Embodiment 2 Fig. 7 is a schematic diagram showing a detection device 200 according to embodiment 2. Hereinafter, the detection device 200 according to embodiment 2 will be described with reference to Fig. 7. In the following description, elements that are the same as or correspond to elements of the detection device 100 according to embodiment 1 are given the same reference numerals, and description thereof will be omitted or simplified.

[0049] While detection apparatus 100 according to the first embodiment obtains a luminance image of unpolarized light, detection apparatus 200 according to the second embodiment obtains a luminance image of polarized light.

[0050] 7, the separation optical system 4 separates the collected light L3 collected by the collecting optical system 3 into unpolarized light L5, a first portion L41 of the polarized light L4, and a second portion L42 of the polarized light L4. In the example of FIG. 7, the separation optical system 4 includes a separation element 71 disposed near the collecting point (or focal point) of the collecting optical system 3. The separation element 71 transmits the unpolarized light L5 and reflects the first portion L41 and the second portion L42 of the polarized light L4 in different directions.

[0051] The detection device 200 includes an imaging unit 72. The imaging unit 72 captures the first portion L41 of the deflected light from the separation optical system 4, and obtains and outputs a luminance image Im2 that indicates a change in the refractive index in the detection region R. The luminance image Im2 is, for example, image data that indicates the luminance values ​​of a plurality of pixels. The luminance image Im2 is, for example, luminance distribution information that indicates the luminance distribution of the first portion L41 of the deflected light. The luminance image Im2 is, for example, an image in which the change in the refractive index in the detection region R is expressed as a difference between light and dark (or contrast). For example, the light captured by the imaging unit 72 includes deflected light deflected by the detection target A and does not include light that has not been deflected, so that the luminance image Im2 is an image in which the luminance value of the image region corresponding to the region where the detection target A exists is greater than the luminance value of the other image regions (or an image in which the image region corresponding to the region where the detection target A exists is brighter than the surroundings). Various cameras can be used as the imaging unit 72. The imaging unit 72 may include an imaging optical system that adjusts the focal length in addition to the camera.

[0052] The spectroscopic section 6 spectroscopically separates the second portion L42 of the polarized light from the separation optical system 4, and obtains and outputs spectral characteristic information Is1 indicating the spectral characteristics of the polarized light.

[0053] The estimation unit 7 estimates the type of the detection object A from the spectroscopic characteristic information Is1 acquired by the spectroscopic unit 6, and outputs type information It1 indicating the estimated type.

[0054] The detection device 200 includes an output unit 73 instead of the output unit 8 in Fig. 1. The output unit 73 outputs a detection result Ir2 including information on the refractive index distribution of the detection region R based on the luminance image Im2 acquired by the imaging unit 72 and information on the type of the detection target A based on the spectroscopic characteristic information Is1 acquired by the spectroscopic unit 6. For example, the output unit 73 causes the display unit 9 to display an output image in which type information It1 is added to the luminance image Im2 as the detection result Ir2. The output unit 73 may be similar to the output unit 8 in the first embodiment, except that the output unit 73 uses the luminance image Im2 instead of the luminance image Im1.

[0055] The detection device 200 may include a stopper 74 that absorbs or blocks the unpolarized light L5 emitted from the separation optical system 4 so that the unpolarized light L5 does not become unnecessary stray light.

[0056] 8 is a schematic perspective view showing an example of the separation element 71. Hereinafter, an example of the separation element 71 will be described with reference to FIGS.

[0057] The separation element 71 is a partially reflecting mirror element. The separation element 71 transmits non-polarized light distributed near the optical axis of the focusing optical system 3 out of the focusing light L3 emitted from the focusing optical system 3 and reflects polarized light distributed outside the vicinity of the optical axis.

[0058] The separation element 71 has a transmitting portion 81 that transmits light, a first reflecting portion 82 located on the periphery of the transmitting portion 81 and having a first reflecting surface 82a that reflects light, and a second reflecting portion 83 located on the periphery of the transmitting portion 81 and having a second reflecting surface 83a that reflects light.

[0059] The separation element 71 is arranged such that the transmission portion 81 is located near the focusing point (or focal point) of the focusing optical system 3, the first and second reflecting surfaces 82a and 83a are inclined with respect to the optical axis of the focusing optical system 3 so as to face in different directions, the non-polarized light L5 passes through the transmission portion 81 and travels along a first optical path, a first portion L41 which is a part of the polarized light L4 is reflected by the first reflecting surface 82a and travels along a second optical path different from the first optical path, and a second portion L42 which is another part of the polarized light L4 is reflected by the second reflecting surface 83a and travels along a third optical path different from the first and second optical paths. The first portion L41 of the polarized light reflected by the first reflecting surface 82a enters the imaging section 72, and the second portion L42 of the polarized light reflected by the second reflecting surface 83a enters the spectroscopic section 6.

[0060] 8, the transmission portion 81 is a central portion located at the center of the separation element 71, and the first and second reflection portions 82 and 83 are peripheral portions located around the central portion. The transmission portion 81 is provided between the first reflection portion 82 and the second reflection portion 83.

[0061] The size of the transmitting portion 81 is approximately equal to or slightly smaller than the size of the focused spot of the focused light L3 when there is no refractive index change (or no detection target A). In Fig. 8, the transmitting portion 81 is a slit, and has a slit width approximately equal to or slightly smaller than the diameter of the focused spot. However, the shape of the transmitting portion 81 may be other shapes.

[0062] The first and second reflecting surfaces 82a and 83a reflect the first and second portions L41 and L42 of the polarized light in different directions from each other. For example, the first and second reflecting surfaces 82a and 83a are both planar, and the directions of their normals are different from each other.

[0063] According to the above-described second embodiment, the following effects can be obtained.

[0064] The detection device 200 includes a light source 1, a separation optical system 4 that separates, among the light emitted from the light source 1 and passing through the detection region R, a polarized light L4 that is a light deflected by a refractive index change in the detection region R, and a non-polarized light L5 that is a light not deflected by the refractive index change, an imaging unit 72 that captures a first portion L41 of the polarized light L4 to obtain a luminance image Im2 that shows the refractive index change in the detection region R, and a spectroscopic unit 6 that disperses a second portion L42 of the polarized light L4 to obtain spectral characteristic information Is1 that shows the spectral characteristics of the polarized light. According to this configuration, it is possible to obtain information on the type of material that has caused the refractive index change, together with the luminance image that shows the refractive index change in the detection region R. In addition, it is possible to estimate the type of material that has caused the refractive index change from the spectral characteristic information Is1.

[0065] Detection device 200 further includes a focusing optical system 3 that focuses light emitted from light source 1 so that unpolarized light is focused at a focusing point, and separation optical system 4 separates polarized light L4 and unpolarized light L5 from the light that has passed through detection region R and been focused by focusing optical system 3. This configuration makes it easy to separate polarized light L4 and unpolarized light L5, enabling the device to be made more compact.

[0066] The separation optical system 4 includes a partially reflective mirror element having a transparent portion 81 that transmits light, a first reflective portion 82 located around the transparent portion 81 and having a first reflective surface 82a that reflects light, and a second reflective portion 83 located around the transparent portion 81 and having a second reflective surface 83a that reflects light, and the partially reflective mirror element is arranged so that the transparent portion 81 is located around the focusing point of the focusing optical system 3 and is inclined with respect to the optical axis of the focusing optical system 3 so that the first and second reflective surfaces 82a and 83a face in different directions, and the non-polarized light L5 passes through the transparent portion 81 and travels along a first optical path, a first portion L41 that is a part of the deflected light L4 is reflected by the first reflective surface 82a and travels along a second optical path different from the first optical path, and a second portion L42 that is the other part of the deflected light L4 is reflected by the second reflective surface 83a and travels along a third optical path different from the first and second optical paths. According to this configuration, the optical path of the non-polarized light L5, the optical path of the first portion L41 of the polarized light L4, and the optical path of the second portion L42 of the polarized light L4 can be separated. This makes it possible to detect the luminance image Im2 and the spectral characteristic information Is1 with high sensitivity even when the refractive index change is small. Specifically, as in the first embodiment, by setting the size of the transmission portion 81 to an appropriate size, the optical path of the non-polarized light and the optical path of the polarized light can be largely separated by the transmission portion (e.g., slit) 81 and the reflecting surfaces 82a and 83a around it. Furthermore, the reflecting surfaces 82a and 83a can largely separate the optical path of the first portion L41 of the polarized light from the optical path of the second portion L42. This makes it easy to arrange the imaging device and the spectroscopic device, and makes it possible to use a relatively large, highly sensitive imaging device and spectroscopic device.

[0067] Embodiment 3 Fig. 9 is a schematic diagram showing a detection device 300 according to embodiment 3. Hereinafter, the detection device 300 according to embodiment 3 will be described with reference to Fig. 9. In the following description, elements that are the same as or correspond to elements of the detection device 100 according to embodiment 1 are given the same reference numerals, and descriptions thereof will be omitted or simplified.

[0068] Detection apparatus 300 according to the third embodiment differs from detection apparatus 100 according to the first embodiment in that it detects the spectral characteristics of unpolarized light and estimates the type of object A to be detected based on the detected spectral characteristics.

[0069] 9, the separation optical system 4 separates the collected light L3 collected by the collecting optical system 3 into a polarized light L4, a first portion L51 of the unpolarized light L5, and a second portion L52 of the unpolarized light L5. In the example of FIG. 9, the separation optical system 4 includes a first separation element 91 and a second separation element 92.

[0070] The first separation element 91 separates the collected light L3 into a polarized light L4 and an unpolarized light L5. The first separation element 91 is, for example, the same as the separation element 10 in FIG.

[0071] The second separation element 92 separates the unpolarized light L5 separated by the first separation element 91 into at least a first portion L51 and a second portion L52. The second separation element 92 is, for example, a beam splitter that transmits a part of the unpolarized light L5 (here, the portion L51) and reflects the other part (here, the portion L52). The second separation element 92 is disposed between the first separation element 91 and the imaging unit 5.

[0072] A first portion L51 of the unpolarized light is incident on the imaging section 5, a second portion L52 of the unpolarized light is incident on the spectroscopic section 93, and polarized light L4 is incident on the spectroscopic section 6.

[0073] The imaging section 5 captures an image of the first portion L51 of the unpolarized light from the separation optical system 4, and obtains and outputs a luminance image Im1.

[0074] The spectroscopic section 6 disperses the polarized light L4 from the separation optical system 4, and obtains and outputs spectral characteristic information Is1 indicating the spectral characteristics of the polarized light.

[0075] The spectroscopic unit 93 spectroscopically separates the second portion L52 of the unpolarized light from the separation optical system 4, and acquires and outputs spectral characteristic information Is2 indicating the spectral characteristics of the unpolarized light. That is, the spectroscopic unit 93 detects the spectral characteristics of the unpolarized light. The spectroscopic unit 93 detects, for example, the intensities of multiple wavelength components of the unpolarized light, and outputs information indicating the intensity of each wavelength component as the spectral characteristic information Is2. Various spectrometers can be used as the spectroscopic unit 93. The spectroscopic unit 93 has, for example, the same detection characteristics as the spectroscopic unit 6.

[0076] The detection device 300 includes an estimating unit 94 and an output unit 95 instead of the estimating unit 7 and the output unit 8 of FIG.

[0077] The estimation unit 94 estimates the type of the detection target A from the spectral characteristic information Is1 acquired by the spectroscopic unit 6, based on the spectral characteristic information Is2 acquired by the spectroscopic unit 93, and outputs type information It2 indicating the estimated type. The estimation unit 94 estimates the type of the detection target A from the spectral characteristic information Is1, for example, using the spectral characteristic information Is2 as standard or reference information. The estimation unit 94 estimates the type of the detection target A by, for example, comparing the spectral characteristic information Is1 with the spectral characteristic information Is2. The estimation unit 94 estimates the type of the detection target A by, for example, performing subtraction or division on the spectral characteristic information Is1, using the spectral characteristic information Is2 as a standard.

[0078] The spectral characteristic information Is1 indicates the spectral characteristics of polarized light, and includes the influence of the spectral characteristics of the medium M (i.e., the material surrounding the detection target A) and the influence of the spectral characteristics of the detection target A. On the other hand, the spectral characteristic information Is2 indicates the spectral characteristics of non-polarized light, and includes the influence of the spectral characteristics of the medium M, but does not include the influence of the spectral characteristics of the detection target A. Therefore, the estimation unit 94 uses, for example, the spectral characteristic information Is2 to remove or reduce the influence of the spectral characteristics of the medium M included in the spectral characteristic information Is1, and estimates the type of the detection target A from the spectral characteristic information obtained thereby. Also, for example, the estimation unit 94 estimates the type of the detection target A based on a comparison (for example, a difference or ratio) between the spectral characteristics indicated by the spectral characteristic information Is1 and the spectral characteristics indicated by the spectral characteristic information Is2.

[0079] The output unit 95 outputs a detection result Ir3 including information on the refractive index distribution of the detection region R based on the luminance image Im1 acquired by the imaging unit 5 and information on the type of the detection target A based on the spectral characteristic information Is1 and Is2 acquired by the spectroscopic units 6 and 93. The information on the type of the detection target A includes the spectral characteristic information Is1 and information obtained from the spectral characteristic information Is1 and Is2. The information obtained from the spectral characteristic information Is1 and Is2 includes type information It2 indicating the type of the detection target A estimated by the estimation unit 94. For example, the output unit 95 causes the display unit 9 to display an output image (or a visualized image of the detection target A) in which the type information It2 is added to the luminance image Im1 as the detection result Ir3. The output unit 95 may be the same as the output unit 8 of the first embodiment, except that the type information It2 is used instead of the type information It1.

[0080] An example of the estimation by the estimation unit 94 will be described below. (First example) If we ignore the difference between the length that unpolarized light travels through medium M and the length that polarized light travels through medium M in detection region R, the spectral intensity I1(λ) of polarized light and the spectral intensity I2(λ) of unpolarized light can be expressed by the following equations (1) and (2), respectively. I1(λ)=I(λ)×Tm(λ)×Ta(λ) …(1) I2(λ)=I(λ)×Tm(λ) …(2) Here, I(λ) is the spectral intensity of the light source 1, Tm(λ) is the spectral transmittance of the medium M, and Ta(λ) is the spectral transmittance of the object A to be detected.

[0081] By dividing the spectral intensity I1(λ) of polarized light by the spectral intensity I2(λ) of unpolarized light, the spectral transmittance Ta(λ) of the object to be detected A is obtained as shown in the following formula (3). I1(λ) / I2(λ)={I(λ)×Tm(λ)×Ta(λ)} / {I(λ)×Tm(λ)}=Ta(λ) …(3)

[0082] Therefore, in the first example, the estimation unit 94 calculates the spectral transmission characteristics of the detection target A by dividing the spectral characteristics of the polarized light indicated by the spectral characteristic information Is1 by the spectral characteristics of the non-polarized light indicated by the spectral characteristic information Is2. Then, the estimation unit 94 compares the calculated spectral transmission characteristics of the detection target A with the spectral transmission characteristics of one or more types of candidate substances to determine the type of the detection target A. For example, the estimation unit 94 calculates the degree of agreement between the calculated spectral transmission characteristics of the detection target A and the spectral transmission characteristics of a certain candidate substance, and if the degree of agreement is higher than a predetermined threshold, determines the type of the candidate substance as the type of the detection target A. In addition, for example, the estimation unit 94 calculates the degree of agreement between the spectral transmission characteristics of the candidate substance and the calculated spectral transmission characteristics of the detection target A for each of a plurality of types of candidate substances, and determines the type of the candidate substance with the highest degree of agreement as the type of the detection target A. Here, the spectral transmission characteristics of each candidate substance are obtained in advance by experiments or the like and stored in the detection device 300 or the like.

[0083] According to this example, as can be seen from the above formula (3), the influence of the spectral characteristics of the medium M and the light source 1 can be eliminated or reduced by division, and the type of the detection target A can be estimated with high accuracy. In addition, the influence of fluctuations in the spectral characteristics of the medium M and the light source 1 due to fluctuations in the environmental temperature and humidity can be eliminated or reduced, and the type of the detection target A can be estimated with high accuracy regardless of the fluctuations in the spectral characteristics of the medium M and the light source 1. Specifically, the spectral intensity I(λ) of light source 1, the spectral transmittance Tm(λ) of medium M, the spectral transmittance Ta(λ) of detection object A, the spectral intensity I1(λ) of polarized light, and the spectral intensity I2(λ) of unpolarized light can be expressed as I(λ,T,H), Tm(λ,T,H), Ta(λ,T,H), I1(λ,T,H), and I2(λ,T,H) as functions of temperature T and humidity H. By dividing the spectral intensity I1(λ, T, H) of polarized light by the spectral intensity I2(λ, T, H) of unpolarized light, the spectral transmittance Ta(λ, T, H) of the object to be detected A is obtained as shown in the following equation (3-2). I1(λ,T,H) / I2(λ,T,H)={I(λ,T,H)×Tm(λ,T,H)×Ta(λ,T,H)} / {I(λ,T,H)×Tm(λ,T,H)}=Ta(λ,T,H) …(3-2) From the above formula (3-2), it can be seen that by dividing by the spectral characteristics of unpolarized light, the effects of fluctuations in the spectral characteristics of the medium M and the light source 1 due to fluctuations in temperature T and humidity H are eliminated. For the same reason, it is possible to eliminate or reduce fluctuations in the spectroscopic detection characteristics of the spectroscopic section 6 due to fluctuations in environmental temperature and humidity, etc., and it is possible to estimate the type of object A to be detected with high accuracy regardless of fluctuations in the spectroscopic detection characteristics of the spectroscopic section 6.

[0084] (Second example) If we ignore the difference between the length that unpolarized light travels through medium M and the length that polarized light travels through medium M in detection region R, the spectral intensity I1(λ) of polarized light and the spectral intensity I2(λ) of unpolarized light can be expressed by the following equations (4) and (5), respectively. I1(λ)=I(λ)-Am(λ)-Aa(λ) …(4) I2(λ)=I(λ)-Am(λ) …(5) Here, I(λ) is the spectral intensity of the light source 1, Am(λ) is the spectral absorption of the medium M, and Aa(λ) is the spectral absorption of the object to be detected A.

[0085] By taking the difference between the spectral intensity I1(λ) of polarized light and the spectral intensity I2(λ) of unpolarized light, the spectral absorption amount Aa(λ) of the object to be detected A is obtained as shown in the following formula (6). I2(λ)-I1(λ)={I(λ)-Am(λ)}-{I(λ)-Am(λ)-Aa(λ)}=Aa(λ) …(6)

[0086] Therefore, in the second example, the estimation unit 94 calculates the spectral absorption characteristics of the detection target A by taking the difference between the spectral characteristics of the polarized light indicated by the spectral characteristic information Is1 and the spectral characteristics of the non-polarized light indicated by the spectral characteristic information Is2. Then, the estimation unit 94 determines the type of the detection target A by comparing the calculated spectral absorption characteristics of the detection target A with the spectral absorption characteristics of one or more types of candidate substances. For example, the estimation unit 94 calculates the degree of agreement between the calculated spectral absorption characteristics of the detection target A and the spectral absorption characteristics of a certain candidate substance, and if the degree of agreement is higher than a predetermined threshold, determines the type of the candidate substance as the type of the detection target A. Also, for example, the estimation unit 94 calculates the degree of agreement between the spectral absorption characteristics of the candidate substance and the calculated spectral absorption characteristics of the detection target A for each of a plurality of types of candidate substances, and determines the type of the candidate substance with the highest degree of agreement as the type of the detection target A. Here, the spectral absorption characteristics of each candidate substance are obtained in advance by experiments or the like and stored in the detection device 300 or the like.

[0087] According to this example, as can be seen from the above formula (6), the effects of the spectral characteristics of the medium M and the light source 1 can be eliminated or reduced by subtraction, and the type of the detection target A can be estimated with high accuracy. In addition, the effects of fluctuations in the spectral characteristics of the medium M and the light source 1 due to fluctuations in the environmental temperature and humidity can be eliminated or reduced, and the type of the detection target A can be estimated with high accuracy regardless of the fluctuations in the spectral characteristics of the medium M and the light source 1.

[0088] In the above first and second examples, the estimation unit 94 may detect a characteristic wavelength range from the spectral characteristics of the detection target A obtained by comparison (e.g., division or subtraction) and compare the spectral characteristics in the characteristic wavelength range. Here, the characteristic wavelength range is, for example, a wavelength range in which a difference appears between the spectral characteristics of the polarized light indicated by the spectral characteristic information Is1 and the spectral characteristics of the non-polarized light indicated by the spectral characteristic information Is2, or a wavelength range in which a feature (e.g., a change, a peak, etc.) of the spectral characteristics of the detection target A appears.

[0089] (Third example) In the third example, the estimation unit 94 first obtains the spectral characteristics of the detection target A by performing division or subtraction, as in the first or second example. Then, the estimation unit 94 detects a characteristic wavelength range from the obtained spectral characteristics of the detection target A. Here, the characteristic wavelength range is the same as described above. Then, the estimation unit 94 determines the type of the detection target A by comparing the detected characteristic wavelength range with the characteristic wavelength ranges of one or more types of candidate substances. In this case, the estimation unit 94 can determine the type of the detection target A by calculating the degree of agreement, as in the first and second examples. Here, the characteristic wavelength range of each candidate substance is, for example, a wavelength range in which a difference in the spectral characteristics of polarized light with respect to the spectral characteristics of unpolarized light appears when the candidate substance is present in the detection region R, or a wavelength range in which a characteristic (e.g., change, peak, etc.) of the spectral characteristics of the candidate substance appears, and is obtained in advance by experiments or the like and stored in the detection device 300 or the like.

[0090] According to this example, the influence of the spectral characteristics of the medium M and the light source 1 can be removed or reduced by division or subtraction, the characteristic wavelength range of the detection object A can be detected with high accuracy, and the type of the detection object A can be estimated with high accuracy.

[0091] Figures 10(A) and 10(B) are diagrams for explaining an example of estimation by the estimation unit 94. Hereinafter, an example of estimation by the estimation unit 94 will be described with reference to Figures 10(A) and 10(B).

[0092] Fig. 10(A) shows the spectral characteristic 101 of polarized light indicated by the spectral characteristic information Is1 acquired by the spectroscopic section 6. The spectral characteristic 101 indicates the intensity of the polarized light for each wavelength. Fig. 10(B) shows the spectral characteristic 102 of unpolarized light indicated by the spectral characteristic information Is2 acquired by the spectroscopic section 93. The spectral characteristic 102 indicates the intensity of the unpolarized light for each wavelength.

[0093] The estimation unit 94 detects the change in the spectroscopic characteristic 101 relative to the spectroscopic characteristic 102 as the spectroscopic characteristic of the detection target A by comparing the spectroscopic characteristic 101 in FIG. 10(A) with the spectroscopic characteristic 102 in FIG. 10(B). For example, the estimation unit 94 obtains the spectroscopic characteristic of the detection target A by taking the difference or ratio between the spectroscopic characteristic 101 and the spectroscopic characteristic 102. Then, the estimation unit 94 detects a characteristic wavelength range 103 from the obtained spectroscopic characteristic of the detection target A. Here, the characteristic wavelength range 103 is a wavelength range from wavelength λ1 to wavelength λ2 (>λ1). Then, the estimation unit 94 compares the spectroscopic characteristic of the detection target A with the inherent spectroscopic characteristic of the specific gas in the detected characteristic wavelength range 103 to determine whether the detection target A is a specific gas. Here, the spectroscopic characteristic of the specific gas is obtained in advance by an experiment or the like and stored in the detection device 300 or the like.

[0094] According to the above-described third embodiment, the following effects can be obtained.

[0095] According to the detection device 300 of the third embodiment, similarly to the first embodiment, it is possible to obtain information on the type of material that has caused the refractive index change, together with a luminance image showing the refractive index change in the detection region R. In addition, it is possible to estimate the type of material that has caused the refractive index change from the spectroscopic characteristic information Is1.

[0096] The detection device 300 includes a spectroscopic unit 6 that acquires spectroscopic characteristic information Is1 indicating the spectroscopic characteristics of polarized light, and a spectroscopic unit 93 that acquires spectroscopic characteristic information Is2 indicating the spectroscopic characteristics of non-polarized light. According to this configuration, the type of the substance that has caused the refractive index change can be estimated with high accuracy from the spectroscopic characteristic information Is1 using the spectroscopic characteristic information Is2 as a reference. Specifically, the spectroscopic characteristics of the detection target A can be detected by comparing the spectroscopic characteristics of the polarized light indicated by the spectroscopic characteristic information Is1 with the spectroscopic characteristics of the non-polarized light indicated by the spectroscopic characteristic information Is2, and the type of the detection target A can be estimated with high accuracy from the detected spectroscopic characteristics. For example, the accuracy of detection of the characteristic wavelength range of the detection target A and the accuracy of estimation of the type of the detection target A based on the spectroscopic characteristics of the detection target A in the characteristic wavelength range can be improved. In addition, the influence of the fluctuation of the spectroscopic characteristics of the medium M, the light source 1, the spectroscopic unit 6, etc. due to the fluctuation of the environmental temperature and humidity can be eliminated or reduced, and the type of the detection target A can be estimated with high accuracy regardless of the fluctuation of the spectroscopic characteristics.

[0097] <Modification> 11 is a schematic diagram showing a detection device 300A according to a modification of embodiment 3. Hereinafter, the detection device 300A according to the modification of embodiment 3 will be described with reference to FIG.

[0098] In the detection device 300A, the separation optical system 4 includes a first separation element 111 and a second separation element 112 instead of the first separation element 91 and the second separation element 92 of FIG.

[0099] The first separation element 111 separates the condensed light L3 condensed by the condensing optical system 3 into polarized light L4 and unpolarized light L5. The first separation element 111 reflects the unpolarized light L5 and transmits the polarized light L4. The first separation element 111 is, for example, a partially reflecting mirror element as shown in FIG. 6. In this case, the unpolarized light L5 is reflected by the reflecting portion 61, and the polarized light L4 is transmitted through the transmitting portion 62.

[0100] The second separation element 112 separates the unpolarized light L5 separated by the first separation element 111 into at least a first portion L51 and a second portion L52. The second separation element 112 is, for example, a beam splitter that transmits a portion of the unpolarized light L5 (here, the portion L51) and reflects the other portion (here, the portion L52).

[0101] A first portion L51 of the unpolarized light is incident on the imaging section 5, a second portion L52 of the unpolarized light is incident on the spectroscopic section 93, and polarized light L4 is incident on the spectroscopic section 6.

[0102] Embodiment 4 Fig. 12 is a schematic diagram showing a detection device 400 according to embodiment 4. Hereinafter, the detection device 400 according to embodiment 4 will be described with reference to Fig. 12. In the following description, elements that are the same as or correspond to elements of the detection device 200 according to embodiment 2 are given the same reference numerals, and description thereof will be omitted or simplified.

[0103] While the detection device 200 according to the second embodiment does not use the unpolarized light L5 separated by the separation optical system 4 for detection, the detection device 400 according to the fourth embodiment detects the spectral characteristics of the unpolarized light L5.

[0104] 12, a detection device 400 includes a spectroscopic unit 121 instead of the stopper 74 in FIG. 7. Also, the detection device 400 includes an estimation unit 122 and an output unit 123 instead of the estimation unit 7 and the output unit 73 in FIG.

[0105] The spectroscopic unit 121 spectroscopically separates the unpolarized light L5 from the separation optical system 4, and acquires and outputs spectral characteristic information Is2 indicating the spectral characteristics of the unpolarized light. The spectroscopic unit 121 is similar to the spectroscopic unit 93 of the third embodiment.

[0106] The estimation unit 122 estimates the type of the detection object A from the spectroscopic characteristic information Is1 acquired by the spectroscopic unit 6, based on the spectroscopic characteristic information Is2 acquired by the spectroscopic unit 121, and outputs type information It2 indicating the estimated type. The estimation unit 122 is similar to the estimation unit 94 in the third embodiment.

[0107] The output unit 123 outputs a detection result Ir4 including information on the refractive index distribution of the detection region R based on the luminance image Im2 acquired by the imaging unit 72, and information on the type of the detection target A based on the spectroscopic characteristic information Is1 and Is2 acquired by the spectroscopic units 6 and 121. For example, the output unit 123 causes the display unit 9 to display an output image in which type information It2 is added to the luminance image Im2 (or a visualized image of the detection target A) as the detection result Ir4. The output unit 123 may be similar to the output unit 73 of the second embodiment except that it uses the type information It2 instead of the type information It1, or may be similar to the output unit 95 of the third embodiment except that it uses the luminance image Im2 instead of the luminance image Im1.

[0108] According to the fourth embodiment described above, in addition to the same effects as in the second embodiment, the same effects as in the third embodiment can be obtained.

[0109] <Variation 1> 13 is a schematic diagram showing a detection device 400A according to a first modification of the embodiment 4. Hereinafter, the detection device 400A according to the first modification of the embodiment 4 will be described with reference to FIG.

[0110] In the detection device 400A, the separation optical system 4 includes a separation element 131 instead of the separation element 71 of Fig. 12. The separation element 131 transmits a first portion L41 of the polarized light L4 and reflects unpolarized light L5 and a second portion L42 of the polarized light L4 in different directions.

[0111] Fig. 14 is a schematic perspective view showing an example of the separation element 131. Hereinafter, an example of the separation element 131 will be described with reference to Figs.

[0112] 14, the separation element 131 is a partially reflecting mirror element. The separation element 131 reflects non-polarized light distributed near the optical axis of the focusing optical system 3 out of the collected light L3, transmits a part of the polarized light distributed outside the vicinity of the optical axis, and reflects the other part.

[0113] The separation element 131 has a first reflecting portion 141 having a first reflecting surface 141a that reflects light, a transmitting portion 142 located around the first reflecting portion 141 and that transmits light, and a second reflecting portion 143 located around the first reflecting portion 141 and that has a second reflecting surface 143a that reflects light.

[0114] The separation element 131 is arranged so that the first reflecting surface 141a is located near the focusing point (or focal point) of the focusing optical system 3, the first and second reflecting surfaces 141a and 143a are inclined with respect to the optical axis of the focusing optical system 3, and the unpolarized light L5 is reflected by the first reflecting surface 141a and travels along a first optical path, a first portion L41 which is a part of the polarized light L4 passes through the transmitting portion 142 and travels along a second optical path different from the first optical path, and the second portion L42 which is the other part of the polarized light L4 is reflected by the second reflecting surface 143a and travels along a third optical path different from the first and second optical paths. The non-polarized light L5 reflected by the first reflecting surface 141a enters the spectroscopic section 121, the first portion L41 of the polarized light that transmits through the transmitting section 142 enters the imaging section 72, and the second portion L42 of the polarized light reflected by the second reflecting surface 143a enters the spectroscopic section 6.

[0115] 14, the first reflecting portion 141 is a central portion located at the center of the separation element 131, the transmitting portion 142 is a first peripheral portion located around the central portion, and the second reflecting portion 143 is a second peripheral portion located around the central portion. The transmitting portion 142 and the second reflecting portion 143 are disposed adjacent to the first reflecting portion 141 and sandwich the first reflecting portion 141 therebetween.

[0116] The first and second reflecting surfaces 141a and 143a reflect the unpolarized light L5 and the second portion L42 of the polarized light in different directions. For example, the first and second reflecting surfaces 141a and 143a are both planar and face in different directions. The directions of the normals of the first and second reflecting surfaces 141a and 143a are different from each other.

[0117] The size of the first reflecting surface 141a is approximately equal to or slightly smaller than the size of the focused spot of the focused light L3 when there is no refractive index change (or no detection target A). In Fig. 14, the first reflecting surface 141a is a strip-shaped flat surface, and has a width approximately equal to or slightly smaller than the diameter of the focused spot. However, the shape of the first reflecting surface 141a may be other shapes.

[0118] Surface 142a of transmitting portion 142 is, for example, continuous with first reflecting surface 141a and forms the same plane. Also, first reflecting portion 141 and transmitting portion 142 can be configured by an integrally molded base material, and first reflecting surface 141a can be formed by evaporating a metal such as aluminum or gold onto a part of the base material. Also, first reflecting portion 141, transmitting portion 142, and second reflecting portion 143 may be configured by an integrally molded base material.

[0119] The transmitting portion 142 of the separation element 131 is a portion that transmits light, and therefore may be a space adjacent to the first reflecting portion 141 as shown in FIG.

[0120] In the above example, a portion of the polarized light that passes through the transmitting section 142 enters the imaging section 72, and a portion of the polarized light that is reflected by the second reflecting surface 143a enters the spectroscopic section 6; however, a portion of the polarized light that is reflected by the second reflecting surface 143a may enter the imaging section 72, and a portion of the polarized light that passes through the transmitting section 142 may enter the spectroscopic section 6.

[0121] <Variation 2> 16 is a schematic diagram showing a detection device 400B according to Modification 2 of Embodiment 4. Hereinafter, with reference to FIG. 16, a detection device 400B according to Modification 2 of Embodiment 4 will be described.

[0122] In the detection device 400B, the separation optical system 4 includes a first separation element 161 and a second separation element 162 instead of the separation element 71 of FIG.

[0123] The first separation element 161 separates the condensed light L3 condensed by the condensing optical system 3 into polarized light L4 and unpolarized light L5. The first separation element 161 transmits the polarized light L4 and reflects the unpolarized light L5. The first separation element 161 is, for example, a partially reflecting mirror element as shown in FIG. 6. In this case, the unpolarized light L5 is reflected by the reflecting portion 61, and the polarized light L4 is transmitted through the transmitting portion 62.

[0124] The second separation element 162 separates the polarized light L4 separated by the first separation element 161 into at least a first portion L41 and a second portion L42. The second separation element 162 is, for example, a beam splitter that transmits a part of the polarized light L4 (here, the part L41) and reflects the other part (here, the part L42).

[0125] The first portion L41 of the polarized light is incident on the imaging section 72, the second portion L42 of the polarized light is incident on the spectroscopic section 6, and the unpolarized light L5 is incident on the spectroscopic section 121.

[0126] <Modification 3> 17 is a schematic diagram showing a detection device 400C according to Modification 3 of Embodiment 4. Hereinafter, the detection device 400C according to Modification 3 of Embodiment 4 will be described with reference to FIG.

[0127] Detector 400C is similar to detector 400B according to Modification 2, except that detector 400C includes second separation element 171 instead of second separation element 162 in FIG.

[0128] The second separation element 171 separates the polarized light L4 from the first separation element 161 into at least a first portion L41 and a second portion L42.

[0129] Fig. 18(A) is a schematic perspective view showing an example of the second separation element 171. In Fig. 18(A), the second separation element 171 has a reflecting portion 181 having a reflecting surface 181a that reflects a portion (here, portion L42) of the polarized light L4 transmitted through the first separation element 161, and a transmitting portion 182 that transmits another portion (here, portion L41) of the polarized light L4.

[0130] The first portion L41 of the polarized light is incident on the imaging section 72, the second portion L42 of the polarized light is incident on the spectroscopic section 6, and the unpolarized light L5 is incident on the spectroscopic section 121.

[0131] Since the transmitting portion 182 of the second separation element 171 is a portion that transmits light, it may be a space adjacent to the reflecting portion 181 as shown in FIG. 18(B).

[0132] Embodiment 5. Fig. 19 is a schematic diagram showing a detection device 500 according to embodiment 5. Hereinafter, the detection device 500 according to embodiment 5 will be described with reference to Fig. 19. In the following description, elements that are the same as or correspond to elements of the detection device 100 according to embodiment 1 are given the same reference numerals, and description thereof will be omitted or simplified.

[0133] The detection device 500 according to the fifth embodiment differs from the detection device 100 according to the first embodiment in that the separation optical system 4 includes a concave reflecting surface.

[0134] 19, the separation optical system 4 includes a concave reflecting surface (or a concave mirror surface) 191, and the concave reflecting surface 191 is configured so that at least a part of the polarized light L4 is reflected by the concave reflecting surface 191 and collected in the spectroscopic section 6.

[0135] The separation optical system 4 includes a separation element 192 instead of the separation element 10 of Fig. 1. The separation element 192 is similar to the separation element 10 of Fig. 1 except that it has a concave reflecting surface 191.

[0136] FIG. 20 is a schematic perspective view showing an example of the separation element 192. In FIG. 20, the separation element 192 is a partial reflection mirror element. The separation element 192 has a transmission part 201 that transmits light, and a reflection part 202 that is located around the transmission part 201 and has a reflection surface 202a that reflects light. The separation element 192 in FIG. 20 is similar to the separation element 10 in FIG. 2, except that the shape of the reflection surface 202a is different from that of the reflection surface 22a. The reflection surface 202a has a curved shape and functions as the concave reflection surface 191. The curved shape of the reflection surface 202a is, for example, a spherical shape, an elliptical shape, an aspherical shape, a free-form shape, or the like.

[0137] According to the fifth embodiment described above, in addition to the effects of the first embodiment, the following effects can be obtained.

[0138] The polarized light reflected by the separation optical system 4 is light collected by the collecting optical system 3, and therefore diffuses after being focused. According to the configuration of this embodiment, the diffused polarized light can be efficiently collected in the spectroscopic unit 6 by the concave reflecting surface 191. This makes it possible to avoid or reduce loss of the polarized light, and to detect the polarized light by the spectroscopic unit 6 with a high signal-to-noise ratio (S / N ratio).

[0139] The concave reflecting surface 191 can be applied not only to the separation optical system 4 of the detection device 100 but also to the separation optical system 4 of other detection devices. For example, in the separation element (or partial reflection mirror element) of other detection devices, the planar reflecting surface that reflects light to the spectroscopic section 6 can be changed to a concave reflecting surface. By using a concave reflecting surface, light can be detected with a high S / N ratio.

[0140] Embodiment 6 Fig. 21 is a schematic diagram showing a detection device 600 according to embodiment 6. Hereinafter, the detection device 600 according to embodiment 6 will be described with reference to Fig. 21. In the following description, elements that are the same as or correspond to elements of the detection device 100 according to embodiment 1 are given the same reference numerals, and descriptions thereof will be omitted or simplified.

[0141] The detection device 600 according to the sixth embodiment differs from the detection device 100 according to the first embodiment in that a spectroscopic camera is used.

[0142] 21, a detection device 600 includes a spectroscopic unit 211 instead of the spectroscopic unit 6 in FIG 1. Also, the detection device 600 includes an output unit 212 instead of the estimation unit 7 and the output unit 8 in FIG 1.

[0143] The spectroscopic unit 211 is a spectroscopic camera that captures the polarized light L4 separated by the separation optical system 4 and obtains a spectroscopic image Im3 that indicates the luminance values ​​of multiple wavelength bands of the polarized light L4 as spectral characteristic information. The spectroscopic image Im3 indicates the spectral characteristics of the polarized light by the luminance values ​​of multiple wavelength bands of the polarized light. Specifically, the spectroscopic image Im3 has multiple pixels, and indicates the luminance values ​​of multiple wavelength bands of the polarized light for each pixel. Therefore, the spectroscopic image Im3 is information that indicates the spectral characteristics of the polarized light for each pixel.

[0144] Similar to the luminance image Im1, the spectral image Im3 is a two-dimensional image with a field of view of the detection region R. From the spectral image Im3, information indicating the position, size, etc. of the detection target A can be extracted, and luminance values ​​(or spectral characteristics) of multiple wavelength bands can be obtained for pixels corresponding to the position of the detection target A.

[0145] FIG. 22 is a schematic diagram showing an example of the configuration of the spectroscopic section (spectroscopic camera) 211. In FIG. 22, the spectroscopic section 211 has a plurality of pixels P11 to Pmn (m and n are integers of 2 or more) arranged two-dimensionally on the imaging surface 221. Each of the plurality of pixels P11 to Pmn has four regions R1, R2, R3, and R4 arranged two-dimensionally. In each pixel, wavelength filters F1, F2, F3, and F4 are provided in the regions R1, R2, R3, and R4, respectively. The wavelength filters F1, F2, F3, and F4 transmit only light in wavelength bands with center wavelengths λ1, λ2, λ3, and λ4 (λ1<λ2<λ3<λ4), respectively. In each region of each pixel, the spectroscopic section 211 detects the luminance value of light in a wavelength band corresponding to the region that has passed through a wavelength filter provided in the region. In this way, the spectroscopic section 211 obtains luminance values ​​of multiple (here, four) wavelength bands of the polarized light for each pixel.

[0146] 23 shows central wavelengths λ1, λ2, λ3, and λ4 of wavelength filters F1, F2, F3, and F4, along with a curve 231 showing an example of the spectral characteristics of polarized light. The central wavelengths λ1, λ2, λ3, and λ4 can be arbitrarily set according to, for example, the inherent spectral characteristics or characteristic wavelengths of an assumed substance (for example, a gas that may flow into medium M).

[0147] The output unit 212 functions as an image generating unit that generates a composite image Im4 in which the spectral image Im3 is superimposed on the luminance image Im1. For example, the output unit 212 compares information on the position, size, contour, etc. of the detection target A in the luminance image Im1 with information on the position, size, contour, etc. of the detection target A in the spectral image Im3, and generates a composite image Im4 in which the spectral image Im3 is superimposed on the luminance image Im1. For example, the output unit 212 causes the display unit 9 to display the composite image Im4 as a detection result.

[0148] The output unit 212 may estimate the type of the detection target A from the spectral image Im3. For example, the output unit 212 may estimate the type of the detection target A for each of one or more regions of the spectral image Im3 from the luminance values ​​of multiple wavelength bands of polarized light in the region (i.e., the spectral characteristics) by, for example, an estimation method similar to that of the first embodiment. Here, each region may be an area composed of one pixel or an area composed of multiple pixels. The output unit 212 may detect the range of the detection target A from the spectral image Im3 and perform the above estimation within the range.

[0149] The output unit 212 may generate an estimation result image showing the result of the estimation. The estimation result image has, for example, a plurality of pixels similar to the spectral image Im3, and shows the estimation result at each pixel. For example, the estimation result image has, for each pixel, a pixel value (for example, a value indicating gradation, color, etc.) corresponding to the estimation result at the pixel. In this case, the output unit 212 may generate a composite image in which the estimation result image is superimposed on the luminance image Im1, and may cause the display unit 9 to display the composite image.

[0150] The output unit 212 may use the spectral image Im3 instead of the spectral characteristic information Is1, and may use an estimation result based on the spectral image Im3 instead of the type information It1, and output a detection result similar to that of the output unit 8 in the first embodiment.

[0151] According to the sixth embodiment described above, in addition to the effects of the first embodiment, the following effects can be obtained.

[0152] In this embodiment, spectroscopic section 211 is a spectroscopic camera that captures at least a part of the polarized light and obtains a spectroscopic image indicating luminance values ​​of multiple wavelength bands of the polarized light as spectral characteristic information of the polarized light. With this configuration, information regarding the type of detection target A can be obtained for each pixel of the spectroscopic image, and the type of detection target A can be estimated in any region of the spectroscopic image.

[0153] The features of the sixth embodiment are applicable not only to the detection device 100 but also to other detection devices. When the features are applied to the second or fourth embodiment, the output unit 212 may use the luminance image Im2 instead of the luminance image Im1. When the features are applied to the third or fourth embodiment, the output unit 212 may estimate the type of the detection target A from the spectral image Im3 based on the spectral characteristic information Is2.

[0154] The hardware configuration of the detection device will be described below. 24 is a block diagram showing an example of a hardware configuration of the detection device 100 according to Embodiment 1. Hereinafter, an example of the hardware configuration of the detection device 100 according to Embodiment 1 will be described with reference to FIG.

[0155] 24, the detection device 100 has a camera 241 as the imaging unit 5, a spectroscope 242 as the spectroscopic unit 6, and a processing circuit 243. The functions of the estimation unit 7 and the output unit 8 of the detection device 100 are realized by the processing circuit 243. The processing circuit 243 may be dedicated hardware, or may be a processor that executes a program stored in a memory.

[0156] When the processing circuit 243 is a dedicated hardware, the processing circuit 243 is, for example, a single circuit, a composite circuit, a programmed processor, a parallel programmed processor, an ASIC (Application Specific Integrated Circuit), an FPGA (Field Programmable Gate Array), or a combination thereof. The functions of the estimation unit 7 and the output unit 8 may be realized by separate processing circuits, or may be realized by a single processing circuit.

[0157] When the processing circuit 243 is a processor, as shown in FIG. 25, the detection device 100 has a processor 251 as the processing circuit 243 and a memory 252. The processor 251 realizes the functions of the estimation unit 7 and the output unit 8 by reading and executing a program stored in the memory 252. The memory 252 stores a program that, when executed by the processor 251, results in the processing of the estimation unit 7 and the output unit 8. It can also be said that the program stored in the memory 252 causes a computer to execute the procedure or method of the estimation unit 7 and the output unit 8. The processor 251 is, for example, a CPU (Central Processing Unit), a processing unit, an arithmetic unit, a microprocessor, a microcomputer, a DSP (Digital Signal Processor), or the like. The memory 252 is, for example, a non-volatile or volatile semiconductor memory such as a random access memory (RAM), a read only memory (ROM), a flash memory, an erasable programmable read only memory (EPROM), an electrically erasable programmable read only memory (EEPROM), a magnetic disk, a flexible disk, an optical disk, a compact disk, a mini disk, a digital versatile disk (DVD), etc. The program stored in the memory 252 is software, firmware, or a combination of these.

[0158] Although the hardware configuration of the detection device 100 according to the first embodiment has been described above, the same applies to the hardware configurations of the other detection devices.

[0159] The detection devices of the above-mentioned embodiments 1 to 6 and their modified examples (hereinafter simply referred to as "the above-mentioned embodiments") may be modified as appropriate. For example, components of the detection devices of the above-mentioned embodiments may be changed, added, or deleted. Furthermore, the features or components of the above-mentioned embodiments may be combined as appropriate in a manner different from that described above.

[0160] In the above embodiment, when estimating the type of a substance, the detection device may estimate components of the substance. For example, the detection device may estimate the types of all or a part of one or more components of the substance.

[0161] In the above embodiment, the detection device may include both an imaging unit that captures unpolarized light to obtain a luminance image Im1 and an imaging unit that captures polarized light to obtain a luminance image Im2. In this case, the output unit can output the detection result based on the luminance images Im1 and Im2.

[0162] In the above embodiment, the configuration of the optical system up to the separation optical system 4 in the detection device may be appropriately changed. For example, one or both of the irradiation optical system 2 and the light collecting optical system 3 may be omitted. The light irradiated to the detection region R may be non-parallel light. The light collecting optical system 3 may be disposed in front of the detection region R, and may be configured to collect the light emitted from the light source 1 and irradiate the detection region R so that the non-polarized light is collected at a light collecting point. Below, with reference to Figs. 26(A) to (C), modified examples of the optical system up to the separation optical system 4 in the detection device 100 are shown. Note that the detection device 100 is taken as an example, but the same applies to the other detection devices mentioned above.

[0163] In FIG. 26(A), the irradiation optical system 2 is configured to collect light emitted from the light source 1 and irradiate the detection region R so that the non-polarized light L5 is collected at the collecting point, and the collecting optical system 3 is omitted. In other words, the collecting optical system 3 is arranged in front of the detection region R, and is configured to collect light emitted from the light source 1 and irradiate the detection region R so that the non-polarized light L5 is collected at the collecting point, and the irradiation optical system 2 is omitted. For example, the collecting optical system 3 in FIG. 26(A) is the same lens as the lens of the irradiation optical system 2 in the first embodiment, but the distance from the lens of the collecting optical system 3 to the light source 1 in FIG. 26(A) is longer than the distance from the lens of the irradiation optical system 2 to the light source 1 in FIG. 1. The separation optical system 4 separates the polarized light L4 and the non-polarized light L5 from the light that passes through the detection region R and is collected by the collecting optical system 3. The separation optical system 4 includes, for example, a separation element 10 arranged near the collecting point of the collecting optical system 3.

[0164] 26(B), the irradiation optical system 2 is omitted, and light emitted from the light source 1 is irradiated onto the detection region R. The light collecting optical system 3 collects the light emitted from the light source 1 and passing through the detection region R so that unpolarized light L5 is collected at the collecting point. The separation optical system 4 separates the light that passes through the detection region R and is collected by the light collecting optical system 3 into polarized light L4 and unpolarized light L5. The separation optical system 4 includes, for example, a separation element 10 arranged near the collecting point of the light collecting optical system 3.

[0165] 26(C), the irradiation optical system 2 and the collection optical system 3 are omitted. The light source 1 is disposed, for example, at a position sufficiently separated from the detection region R, and irradiates the detection region R with parallel light. The separation optical system 4 separates the light that has passed through the detection region R into polarized light L4 and unpolarized light L5. The separation optical system 4 includes, for example, a separation element 10 disposed on the optical axis of the unpolarized light L5.

[0166] In the above embodiment, the configuration of the separation optical system 4 may be appropriately changed. Various configurations of the separation optical system 4 will be shown below with reference to FIG. 27. In FIG. 27, the separation optical system 4 includes a separation element 261 that separates the polarized light L4 and the non-polarized light L5 from the light (e.g., the collected light L3) that has passed through the detection region R. The separation element 261 is, for example, any of the above-mentioned partially reflecting mirror elements. The separation optical system 4 may include a separation element 262 that separates one of the polarized light L4 and the non-polarized light L5 separated by the separation element 261 into at least two parts. The separation optical system 4 in FIG. 27 can be used in the detection device of the above embodiment.

[0167] In the above embodiment, the refractive index change in the detection region R may occur due to the inflow of foreign matter into the medium M, or may occur due to a density change (or density gradient) in the medium M. Therefore, the detection target A may be the same type of substance as the medium M. For example, the detection target A may be a part of the medium M having a different density from the surroundings. The density change in the medium M may occur due to, for example, a temperature gradient, a pressure gradient (e.g., an air pressure gradient), or the like. When the refractive index change occurs due to a density change, the luminance image acquired by the detection device is an image showing the density change (or density distribution) in the detection region R, and the detection device can detect the presence or absence of a density change in the detection region R, the location of the change, etc.

[0168] In the above embodiment, the deflection of light by the object to be detected A may be any of refraction caused by the difference in refractive index between the medium M and the object to be detected A, refraction caused by the difference in density between the medium M and the object to be detected A, and scattering of light caused by the object to be detected A.

[0169] The detection device of the above embodiment can detect the presence or absence, position, etc. of a refractive index change (or density change) occurring in a medium. The detection device can optically detect, for example, invisible gas or liquid flow in a medium, invisible substance flow in an invisible medium (for example, exhaled airflow, gas refrigerant leak, etc.), progress of ultrasonic waves or shock waves propagating in a medium, rising airflow caused by a flame, defects in optical components, etc. The detection device can also detect a refractive index change (or density change) occurring in a medium as well as a substance related to the change. For example, when a refractive index change (or density change) occurs in a medium, the detection device can detect information on the type of substance that caused the refractive index change as well as the location where the refractive index change occurred. For example, the detection device can detect or visualize the flow of gas in the air and detect information on the type of the gas. It can also determine whether the gas in the air is a specific gas to be detected.

[0170] The detection device of the above embodiment can be applied to various industrial fields. For example, the detection device can be applied to a gas leak detection device, a human or animal breath detection device, a driver monitor system (DMS) that detects the breath of a passenger in a vehicle to detect the passenger's health condition, an airflow detection device, a hot or cold air temperature airflow detection device of an air conditioner or other air conditioning device or an air conditioning control device of an air conditioner using the same, a refrigerant leak detection device of an air conditioner or other device, a detection device for foreign matter in a liquid, an inspection device for inhomogeneity or defects in solid materials such as semiconductors, a striae inspection device for optical components, etc. By applying the detection device of the above embodiment, more suitable control and maintenance of the equipment is possible. [Explanation of symbols]

[0171] 1 light source, 2 irradiation optical system, 3 focusing optical system, 4 separation optical system, 5 imaging section, 6 spectroscopic section, 7 estimation section, 8 output section, 9 display section, 10 separation element, 100 detection device.

Claims

1. A light source; a separation optical system that separates light emitted from the light source and passing through a predetermined detection area into polarized light, which is light that has been deflected by a refractive index change in the detection area, and non-polarized light, which is light that has not been deflected by the refractive index change; an imaging unit that images at least one of at least a portion of the unpolarized light and at least a portion of the polarized light to obtain a luminance image that indicates a refractive index change in the detection region; a first spectroscopic unit that disperses at least a portion of the polarized light to obtain first spectral characteristic information indicating a spectral characteristic of the polarized light; a focusing optical system that focuses the light emitted from the light source so that the unpolarized light is focused at a focusing point, the separation optical system separates the polarized light and the unpolarized light from the light that has passed through the detection area and been collected by the collection optical system; the separation optical system includes a partially reflecting mirror element having a transmission portion that transmits light and a reflection portion that is located around the transmission portion and has a reflection surface that reflects light, The partially reflecting mirror element is disposed such that the transmitting portion is located near the light collecting point, the reflecting surface is inclined with respect to the optical axis of the light collecting optical system, the unpolarized light is transmitted through the transmitting portion and travels along a first optical path, and the polarized light is reflected by the reflecting surface and travels along a second optical path different from the first optical path. Detection device.

2. A light source; a separation optical system that separates light emitted from the light source and passing through a predetermined detection area into polarized light, which is light that has been deflected by a refractive index change in the detection area, and non-polarized light, which is light that has not been deflected by the refractive index change; an imaging unit that images at least one of at least a portion of the unpolarized light and at least a portion of the polarized light to obtain a luminance image that indicates a refractive index change in the detection region; a first spectroscopic unit that disperses at least a portion of the polarized light to obtain first spectral characteristic information indicating a spectral characteristic of the polarized light; a focusing optical system that focuses the light emitted from the light source so that the unpolarized light is focused at a focusing point, the separation optical system separates the polarized light and the unpolarized light from the light that has passed through the detection area and been collected by the collection optical system; the separation optical system includes a partially reflecting mirror element having a reflecting portion having a reflecting surface that reflects light, and a transmitting portion that is located around the reflecting portion and transmits light; The partially reflective mirror element has a reflecting surface located near the focusing point and tilted with respect to the optical axis of the focusing optical system, and is disposed such that the unpolarized light is reflected by the reflecting surface and travels along a first optical path, and the polarized light is transmitted through the transmitting portion and travels along a second optical path different from the first optical path. Detection device.

3. A light source; a separation optical system that separates light emitted from the light source and passing through a predetermined detection area into polarized light, which is light that has been deflected by a refractive index change in the detection area, and non-polarized light, which is light that has not been deflected by the refractive index change; an imaging unit that images at least one of at least a portion of the unpolarized light and at least a portion of the polarized light to obtain a luminance image that indicates a refractive index change in the detection region; a first spectroscopic unit that disperses at least a portion of the polarized light to obtain first spectral characteristic information indicating a spectral characteristic of the polarized light; a focusing optical system that focuses the light emitted from the light source so that the unpolarized light is focused at a focusing point, the separation optical system separates the polarized light and the unpolarized light from the light that has passed through the detection area and been collected by the collection optical system; the separation optical system includes a partially reflecting mirror element having a transmitting portion that transmits light, a first reflecting portion located on the periphery of the transmitting portion and having a first reflecting surface that reflects light, and a second reflecting portion located on the periphery of the transmitting portion and having a second reflecting surface that reflects light, The partially reflective mirror element is disposed such that the transmitting portion is located near the light-collecting point, the first and second reflecting surfaces are inclined with respect to the optical axis of the light-collecting optical system so as to face in different directions, the unpolarized light is transmitted through the transmitting portion and travels along a first optical path, a portion of the polarized light is reflected by the first reflecting surface and travels along a second optical path different from the first optical path, and another portion of the polarized light is reflected by the second reflecting surface and travels along a third optical path different from the first and second optical paths. Detection device.

4. A light source; a separation optical system that separates light emitted from the light source and passing through a predetermined detection area into polarized light, which is light that has been deflected by a refractive index change in the detection area, and non-polarized light, which is light that has not been deflected by the refractive index change; an imaging unit that images at least one of at least a portion of the unpolarized light and at least a portion of the polarized light to obtain a luminance image that indicates a refractive index change in the detection region; a first spectroscopic unit that disperses at least a portion of the polarized light to obtain first spectral characteristic information indicating a spectral characteristic of the polarized light; a focusing optical system that focuses the light emitted from the light source so that the unpolarized light is focused at a focusing point, the separation optical system separates the polarized light and the unpolarized light from the light that has passed through the detection area and been collected by the collection optical system; the separation optical system includes a partially reflecting mirror element having a first reflecting portion having a first reflecting surface that reflects light, a transmitting portion located around the first reflecting portion and transmitting light, and a second reflecting portion located around the first reflecting portion and having a second reflecting surface that reflects light; The partially reflective mirror element is disposed such that the first reflecting surface is located near the focusing point, the first and second reflecting surfaces are inclined with respect to an optical axis of the focusing optical system, the unpolarized light is reflected by the first reflecting surface and travels along a first optical path, a portion of the polarized light is transmitted through the transmitting portion and travels along a second optical path different from the first optical path, and another portion of the polarized light is reflected by the second reflecting surface and travels along a third optical path different from the first and second optical paths. Detection device.

5. an output unit that outputs an output image in which information on the type of material that caused the refractive index change based on the first spectroscopic characteristic information is added to the luminance image; 5. A detection device according to claim 1.

6. The imaging section captures an image of at least a portion of the unpolarized light to obtain the luminance image.

6. A detection device according to claim 1 .

7. the separation optical system separates the unpolarized light, a first portion of the polarized light, and a second portion of the polarized light from the light that has passed through the detection area; the imaging unit images a first portion of the deflected light to obtain the luminance image; The first spectroscopic unit disperses a second portion of the polarized light to obtain the first spectroscopic characteristic information.

6. A detection device according to claim 1 .

8. the separation optical system separates the polarized light, a first portion of the unpolarized light, and a second portion of the unpolarized light from the light that has passed through the detection area; the imaging section images a first portion of the unpolarized light to obtain the luminance image; The detection apparatus further includes a second spectroscopic unit that disperses a second portion of the unpolarized light to obtain second spectral characteristic information indicative of a spectral characteristic of the unpolarized light.

7. The detection device according to claim 6.

9. a second spectroscopic unit that disperses at least a portion of the unpolarized light to obtain second spectral characteristic information indicating a spectral characteristic of the unpolarized light.

8. The detection device according to claim 7.

10. The optical fiber further includes an estimation unit that estimates a type of a substance that has caused a change in refractive index from the first spectroscopic characteristic information acquired by the first spectroscopic unit.

10. A detection device according to any one of claims 1 to 9.

11. The optical fiber further includes an estimation unit that estimates a type of a substance that has caused a change in refractive index from the first spectroscopic characteristic information acquired by the first spectroscopic unit based on the second spectroscopic characteristic information acquired by the second spectroscopic unit.

10. A detection device according to claim 8 or 9.

12. The first spectroscopic unit is a spectroscopic camera that captures an image of at least a portion of the polarized light and obtains a spectroscopic image indicating luminance values ​​of a plurality of wavelength bands of the polarized light as the first spectroscopic characteristic information. Detecting device according to any one of claims 1 to 11.

13. an image generating unit that generates a composite image by superimposing the spectral image on the luminance image; 13. The detection device of claim 12.

14. separating, from light emitted from a light source and passing through a predetermined detection region, polarized light that is light deflected by a refractive index change in the detection region, and non-polarized light that is light not deflected by the refractive index change; capturing an image of at least one of at least a portion of the unpolarized light and at least a portion of the polarized light to obtain a luminance image indicative of a refractive index change in the detection region; dispersing at least a portion of the polarized light to obtain first spectral characteristic information indicating a spectral characteristic of the polarized light; and focusing the light emitted from the light source using a focusing optical system such that the unpolarized light is focused at a focusing point; the separating step includes separating the polarized light and the unpolarized light from the collected light that passes through the detection region; the separating step includes separating the light beams using a partially reflecting mirror element having a transmitting portion that transmits light and a reflecting portion that is located around the transmitting portion and has a reflecting surface that reflects the light beams; The partially reflecting mirror element is disposed such that the transmitting portion is located near the light collecting point, the reflecting surface is inclined with respect to the optical axis of the light collecting optical system, the unpolarized light is transmitted through the transmitting portion and travels along a first optical path, and the polarized light is reflected by the reflecting surface and travels along a second optical path different from the first optical path. Detection methods.

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