Spectroscopic analysis device and spectroscopic analysis method

Abstract

To provide a spectroscopic analysis device or a spectroscopic analysis method that obtains a spectrum of an object to be analyzed by a transmission wavelength-tunable optical filter using a Fabry-Perot (FP) structure, and can detect the actual transmission peak wavelength of the transmission wavelength-tunable optical filter.SOLUTION: A spectroscopic analysis device comprises an imaging element, a transmission wavelength-tunable FP optical filter A, and a film thickness gradient FP spectral filter B. A part of incident light transmits through both the optical filter A and the spectral filter B and reaches the imaging element, and the remaining incident light reaches the imaging element without transmitting through the spectral filter B. A spectroscopic analysis method includes, in spectroscopic analysis of incident light of the optical filter A, making a part of light transmitted through the optical filter A incident on the spectral filter B, and detecting the transmission peak wavelength of the optical filter A using, as an index, the transmission peak wavelength of the spectral filter B or the transmission peak wavelength of the optical filter A of a part of incident light that is dispersed and transmitted by the spectral filter B and is made incident.SELECTED DRAWING: Figure 7

Description

[Technical Field]

[0001] The present invention relates to a spectroscopic analysis device and a spectroscopic analysis method. [Background technology]

[0002] Spectrometers are instruments that measure the energy intensity of light wavelengths. Recently, their applications have expanded beyond academic fields, from everyday life to industrial applications. For example, by obtaining the spectrum of fresh food using a spectrometer, it is possible to obtain information such as freshness and sugar content. Other promising applications include using skin spectra obtained with a spectrometer to provide beauty advice, and using spectra obtained from spectrometers mounted on endoscopes to monitor the condition of living organs and tissues. Furthermore, obtaining spectra of finished or semi-finished products during the manufacturing process of processed foods and industrial products can enable the identification of defective products that cannot be identified with conventional cameras. Furthermore, by installing spectrometers on drones, airplanes, and satellites, they can be used to survey light environments over a wide area. Furthermore, by installing spectrometers on wearable devices, it is possible to obtain information about the light environment in which one is exposed. Thus, spectrometers are expected to be applied in a variety of fields.

[0003] Hyperspectral imaging, which obtains image information with high wavelength resolution, is known as an advanced spectroscopic analysis technology. For example, while an RGB camera can only distinguish three bands, a hyperspectral camera can obtain detailed wavelength information in more than 100 bands. This makes it possible to visualize information that is invisible to the naked eye, and it is used in a wide range of fields, from food to agriculture to space.

[0004] Conventional hyperspectral cameras are available in two types: a line type, which measures one line at a time while moving the object being measured or the camera itself, and a filter array type, which uses a mosaic filter array to capture images for each wavelength at once. Line-type hyperspectral cameras require the measurement object and the camera to be driven, which places limitations on how small the device can be. Figure 1 shows an example of the structure of a filter array hyperspectral camera. Because a filter array hyperspectral camera places optical filters for each band on the sensor, it has no moving parts and can perform hyperspectral imaging with a single camera. However, because optical filters are placed on the sensor for each band, there is a trade-off between increasing the number of bands and improving spatial resolution. Figure 2 shows schematic diagrams of optical filter arrays for (a) low wavelength resolution and high spatial resolution, and (b) high wavelength resolution and low spatial resolution. The number of squares indicated by dashed lines corresponds to the spatial resolution. Increasing the number of optical filters on the same imaging element (CMOS image sensor or CCD image sensor) to improve wavelength resolution results in a decrease in the spatial resolution of the image, as shown in Figure 2(b). Therefore, practical filter array hyperspectral cameras often have relatively low wavelength resolution, with only a dozen or so bands. Thus, it is difficult to realize a hyperspectral camera using a filter array that can both increase wavelength resolution to acquire more detailed wavelength information and achieve high spatial resolution.

[0005] A hyperspectral camera using a wavelength-tunable optical filter with variable transmission characteristics has been proposed as a hyperspectral camera that increases both the number of bands and spatial resolution while also aiming to reduce the size of the device. Figure 3 shows the mechanism of a wavelength-tunable optical filter-based hyperspectral camera. With a wavelength-tunable optical filter, the transmission characteristics of the optical filter are variable, and by controlling the transmission characteristics, it is possible to capture images for each wavelength. Therefore, hyperspectral imaging is possible with a single camera without any moving parts like in the line method, and high wavelength resolution can be achieved without sacrificing spatial resolution.

[0006] One of the principles of wavelength-tunable optical filters currently being proposed is the Fabry-Perot (FP) interferometer, which uses a multilayer film. Figure 4 shows a schematic diagram of an FP interferometer. An FP interferometer is an optical system consisting of a multilayer film made of two mirrors (reflective layers (R)) and a transparent medium (M) between them. Depending on the refractive index of the transparent medium and the distance between the mirrors, transmitted light of a specific wavelength is intensified. In other words, when the phase difference between the zeroth-order transmitted light and higher-order transmitted light at a certain wavelength λ becomes zero, that wavelength λ is selectively transmitted. This allows the Fabry-Perot (FP) interferometer to function as a wavelength-tunable optical filter. The FP interferometer itself is well known; see, for example, Non-Patent Document 1. As an example of a hyperspectral camera using a FP interferometer, HinaLea Imaging has launched a hyperspectral camera (4200C) that uses a FP structure to cover the visible-near-infrared range of 400 to 1000 nm, has 300 bands, a full width at half maximum of 4 nm, and dimensions of 85 mm x 59 mm x 70 mm. As a research example of a transmission wavelength tunable optical filter using a FP interferometer, an air-gap FP optical filter has been reported, in which air is used as the transparent medium and the air gap between metal thin films is controlled using Micro Electro Mechanical Systems (MEMS) technology (Non-Patent Document 2). An example of this air-gap FP optical filter is shown in Figure 5. The upper side of Figure 5 is a cross-sectional view, and the lower side is a top view. This air-gap FP optical filter has two glass substrates (1) on each of which an Ag alloy film (2) is formed as a mirror, and the transparent medium between the two mirrors (4, the transparent medium filling the gap) is air. The peak wavelength of the transmitted light is controlled by changing the air gap (4) between the two Ag alloy films (2) using an electrostatic actuator (3) using indium tin oxide (ITO) electrodes on the inside of the two glass substrates (1). Furthermore, as an example of an air-gap FP optical filter targeting the far-infrared, an air-gap FP optical filter has been proposed that uses a distributed Bragg reflector mirror in which layers of Ge, a high-refractive index material, and ZnS, a low-refractive index material, are alternately stacked (Non-Patent Document 3). In this air-gap FP optical filter, the air gap or transmission peak wavelength is controlled by an electrostatic actuator using Au electrodes for driving formed around the mirror.

[0007] A wavelength-tunable optical filter using a FP interferometer can also use liquid crystal as the transparent medium instead of air. In this case, the molecular orientation of the liquid crystal is controlled by adjusting the voltage. This molecular orientation control changes the refractive index of the transparent medium, allowing the transmission peak wavelength to be adjusted to the desired wavelength.

[0008] To commercialize a hyperspectral camera using the air-gap FP optical filter, it is necessary to incorporate a function to monitor the accuracy of the air gap (the distance between the two mirrors) control of the air-gap FP optical filter, either before starting measurement or in real time. For example, when controlling the air gap using the electrostatic actuator, the driving performance of the electrostatic actuator can change due to the influence of the measurement environment (e.g., temperature, humidity, etc.). This changes the relationship between the applied voltage and the air gap, which in turn changes the relationship between the applied voltage and the optical transmission characteristics of the air-gap FP optical filter. By detecting this change in the relationship between the applied voltage and the air gap, it is possible to perform calibration before measurement and accurately control the transmission wavelength of the wavelength-tunable optical filter to the desired wavelength. To achieve this, it has been proposed to incorporate a capacitive displacement sensor into the air-gap FP optical filter to monitor the accuracy of gap control. However, this method requires dedicated wiring and a capacitance detection circuit for the capacitive displacement sensor, which limits the miniaturization of the hyperspectral camera.

[0009] Furthermore, when liquid crystal is used instead of air as the transparent medium of a transmission wavelength tunable optical filter, the relationship between the applied voltage and the liquid crystal orientation or refractive index may change due to the influence of the measurement environment, etc.

[0010] A technique for calibrating a transmission wavelength tunable optical filter using an optical method has also been proposed. For example, Patent Document 1 states: 1. A method for self-calibrating a tunable Fabry-Perot cavity, comprising: Step S1: irradiating incident light onto a filter glass, transmitting the incident light through a calibration filter film on the filter glass, and obtaining calibration light having a fixed wavelength; Step S2 of strobing the calibration light through the Fabry-Perot cavity to obtain strobe light after transmission through the Fabry-Perot cavity; and step S3 of irradiating the strobe light onto an imaging chip to perform imaging and obtain an output signal. According to the calibration method described in Patent Document 1, the calibration light reaches the imaging chip (image sensor) only when the air gap of the Fabry-Perot cavity, which is a transmission wavelength tunable optical filter, matches the wavelength of the calibration light, so it is said that the relationship between the applied voltage and the air gap can be self-calibrated in real time. [Prior art documents] [Patent documents]

[0011] [Patent Document 1] Japanese Patent Publication No. 2022-524361 [Non-patent literature]

[0012] [Non-Patent Document 1] ACS Photonics, 2015, Volume 2, p.183-188 [Non-patent document 2] IEEJ Transactions on Sensors and Micromachines, Vol. 132, No. 2, pp. 25-30, 2012 [Non-patent document 3] JOURNAL OF MICROELECTROMECHANICAL SYSTEMS, 2016, Vol. 25, No. 1, pp. 227-235 Summary of the Invention [Problem to be solved by the invention]

[0013] The self-calibration method for a Fabry-Perot cavity described in Patent Document 1 performs calibration using calibration light obtained by selectively transmitting light of a specific wavelength from incident light, without using a capacitive displacement sensor. Therefore, this technology can be said to be capable of realizing miniaturization of hyperspectral cameras. However, this calibration method calibrates the drive voltage or air gap based on the wavelength of calibration light of several fixed wavelengths. In other words, the drive voltage of the transmission wavelength tunable optical filter is controlled to match the air gap with the wavelength of the calibration light, and the deviation in the relationship between the drive voltage and the air gap is calibrated based on this. However, it cannot directly, instantaneously, or accurately capture the wavelength of the transmission light of the transmission wavelength tunable optical filter itself.

[0014] The present invention aims to provide a spectroscopic analyzer that obtains the spectrum of an object to be analyzed using a transmission wavelength tunable optical filter that uses an FP structure, and that can directly detect the actual transmission peak wavelength of the transmission wavelength tunable optical filter in spectroscopic analysis. Another object of the present invention is to provide a spectroscopic analysis method for obtaining a spectrum of an object to be analyzed using a transmission wavelength tunable optical filter with an FP structure, which can directly detect the actual transmission peak wavelength of the transmission wavelength tunable optical filter in spectroscopic analysis. [Means for solving the problem]

[0015] The above-mentioned problems of the present invention have been solved by the following means. [1] The optical filter includes an image sensor, a wavelength-tunable optical filter A, and a thickness-gradient spectral filter B, and the wavelength-tunable optical filter A has a reflective layer R on the light-incident side. a1 and the reflective layer R on the light exit side a2 and are arranged in parallel, and the reflective layer R a1 and the reflective layer R a2 and the thickness gradient spectral filter B has a Fabry-Perot structure in which the distance or refractive index between the reflective layer R and the b1 and the reflective layer R on the light exit side b2 a Fabry-Perot structure in which the distance between the filter A and the spectral filter B increases continuously in one direction, and a portion of the incident light passes through both the tunable optical filter A and the spectral filter B to reach the image sensor, and the remaining incident light passes through the tunable optical filter A but reaches the image sensor without passing through the spectral filter B. [2] The spectroscopic analysis device according to [1], wherein the peak transmission wavelength of the transmission wavelength tunable optical filter A in spectroscopic analysis is detected using as an index the peak transmission wavelength of the gradient thickness spectral filter B into which a portion of the transmitted light of the transmission wavelength tunable optical filter A is incident, or a portion of the incident light is separated into wavelengths by the gradient thickness spectral filter B and transmitted, and the peak transmission wavelength of the transmission wavelength tunable optical filter A into which this separated transmitted light is incident is used as an index. [3] The spectroscopic analysis device according to [2], wherein the peak transmission wavelength of the tunable optical filter A is detected based on the position at which light of the peak transmission wavelength that has passed through both the tunable optical filter A and the gradient thickness spectral filter B reaches the imaging element. [4] The reflective layer R a2 is disposed on the substrate a2, and the reflective layer R a2 The spectroscopic analyzer according to any one of [1] to [3], wherein the gradient thickness spectral filter B is disposed on a part of the surface opposite to the surface of the spectroscopic analyzer. [5] The spectroscopic analyzer according to any one of [1] to [3], wherein the gradient thickness spectral filter B is disposed on the imaging element. [6] The thickness gradient spectral filter B is configured to reflect the light emitted from the reflective layer R at least in the wavelength range of 400 to 700 nm. b1 and the reflective layer R b2 The spectroscopic analyzer according to any one of [1] to [5], wherein light of a specific wavelength is transmitted selectively in a position in a film thickness gradient direction depending on the distance from the film thickness gradient direction. [7] The reflective layer R b1 and the reflective layer R b2 The spectroscopic analyzer according to any one of [1] to [6], wherein an SiO2 layer is provided between the [8] The reflective layer R a1 and the reflective layer R a2 The spectroscopic analyzer according to any one of [1] to [7], wherein an air layer is present between the [9] By detecting the transmission peak wavelength of the transmission wavelength tunable optical filter A, the reflection layer R a1 and the reflective layer R a2 The spectroscopic analyzer according to [8], which detects the distance between

[10] The reflective layer R a1 and the reflective layer R a2 The spectroscopic analyzer according to any one of [1] to [7], wherein a liquid crystal layer is provided between the

[11] The spectroscopic analyzer according to

[10] , wherein the refractive index of the liquid crystal layer is detected by detecting the transmission peak wavelength of the transmission wavelength tunable optical filter A.

[12] Reflective layer R on the light incident side a1 and the reflective layer R on the light exit side a2 and are arranged in parallel, and the reflective layer R a1 and the reflective layer R a2 When a wavelength-tunable optical filter A having a Fabry-Perot structure in which the distance or refractive index between the reflective layer R on the light-incident side is tunable is used to perform spectroscopic analysis of light incident on the wavelength-tunable optical filter A, b1and the reflective layer R on the light exit side b2 a spectral analysis method comprising: making a portion of the transmitted light of the wavelength-tunable optical filter A incident on a gradient thickness spectral filter B having a gradient thickness Fabry-Perot structure in which the distance between the wavelength-tunable optical filter A and the incident light is continuously increased in one direction; and detecting the peak transmission wavelength of the wavelength-tunable optical filter A in the spectroscopic analysis using the peak transmission wavelength of the wavelength-tunable optical filter B as an index; or separating a portion of the incident light into wavelengths by the gradient thickness spectral filter B and transmitting the separated transmitted light; and detecting the peak transmission wavelength of the wavelength-tunable optical filter A as an index.

[13] The spectroscopic analysis method according to

[12] , wherein the transmission peak wavelength of the transmission wavelength tunable optical filter A is detected based on the position at which light of the transmission peak wavelength that has passed through both the transmission wavelength tunable optical filter A and the thickness gradient spectral filter B reaches the image sensor. [Effects of the Invention]

[0016] The spectroscopic analysis device of the present invention obtains the spectrum of an analyte using a transmission wavelength-tunable optical filter with an FP structure, and can directly detect the actual transmission peak wavelength of the transmission wavelength-tunable optical filter during spectroscopic analysis. Therefore, when the environment in which the spectroscopic analysis is performed (such as the installation location of the device) changes, it is possible to calibrate the spectroscopic analysis device before performing the spectroscopic analysis and accurately control the transmission wavelength of the transmission wavelength-tunable optical filter to a desired wavelength. It is also possible to check in real time the accuracy of the control of the transmission wavelength by the transmission wavelength-tunable optical filter during spectroscopic analysis. Furthermore, the spectroscopic analysis method of the present invention obtains the spectrum of an analyte using a transmission wavelength-tunable optical filter with an FP structure, and can directly detect the actual transmission peak wavelength of the transmission wavelength-tunable optical filter during spectroscopic analysis. [Brief explanation of the drawings]

[0017] [Figure 1]FIG. 1 is an explanatory diagram showing the mechanism of a filter array type hyperspectral camera. [Figure 2] 1A and 1B are schematic diagrams of optical filter arrays in the cases of low wavelength resolution and high spatial resolution (a) and high wavelength resolution and low spatial resolution (b). [Figure 3] FIG. 1 is an explanatory diagram showing the mechanism of a hyperspectral camera using a transmission wavelength tunable optical filter. [Figure 4] Schematic diagram of a Fabry-Perot (FP) interferometer. [Figure 5] 1A and 1B are a cross-sectional view and a top view schematically showing an example of an air-gap FP optical filter. [Figure 6] 1 is a schematic diagram of a gradient film thickness spectral filter B and an explanatory diagram showing the film formation principle of a gradient film. [Figure 7] 1 is a cross-sectional view schematically showing an example of the layer structure of a first embodiment of a spectroscopic analyzer of the present invention. [Figure 8] FIG. 2 is an explanatory diagram showing the optical principle of a spectroscopic analyzer when an air-gap FP optical filter is driven. [Figure 9] 10 is a graph showing the results of a rigorous coupled wave analysis of the optical transmittance of an FP structure in which, in the design of gradient thickness spectral filter B, the thicknesses of the reflective layers Rb1 and Rb2 are 30 nm and a gradient SiO2 film with a thickness of 75 to 185 nm is placed between the reflective layers Rb1 and Rb2. [Figure 10] 10 is a graph showing the results of a rigorous coupled-wave analysis of the optical transmittance of an FP structure in which the reflective layers Ra1 and Ra2 are formed with a thickness of 30 nm from an Ag alloy and the air gap is movable in the range of 130 to 300 nm in the design of a transmission wavelength tunable optical filter A. [Figure 11] 1 is a diagram schematically illustrating a cross section of an optical system of a spectroscopic analyzer designed in an example. [Figure 12] 10 is a diagram showing a film formation range (multilayer film formation area) for forming a gradient thickness spectral filter B on a lower substrate. [Figure 13] 10A to 10C are explanatory diagrams showing the manufacturing process of an upper substrate with a reflective layer Ra1. [Figure 14]10A to 10C are explanatory diagrams showing the manufacturing process of a lower substrate with a reflective layer Ra2 and a gradient thickness spectral filter B. [Figure 15] 10A to 10C are explanatory diagrams showing the manufacturing process of a lower substrate with a reflective layer Ra2 and a gradient thickness spectral filter B. [Figure 16] 10 is a photograph, used as a substitute for a drawing, of the fabricated lower substrate with a reflective layer Ra2 and a gradient thickness spectral filter B, taken after step (g) and before step (h). [Figure 17] 17 is a graph showing the relationship between the position x and the peak wavelength when the position x shown in FIG. 16 is between 0.00 mm (the right end of the arrow) and 2.50 mm (the left end of the arrow). [Figure 18] 10A to 10C are explanatory diagrams showing the assembly (optical system formation) process of an optical filter using the manufactured upper and lower substrates and piezoelectric elements. DETAILED DESCRIPTION OF THE INVENTION

[0018] [Spectroscopic analyzer] The spectroscopic analyzer of the present invention includes an imaging element, a transmission wavelength tunable optical filter A, and a gradient thickness spectral filter B. The above-mentioned transmission wavelength tunable optical filter A has a reflective layer R a1 and a reflective layer R, which is a mirror on the light exit side. a2 and are arranged parallel (including a state in which they are approximately parallel within a range that does not impair the effects of the present invention), and the reflective layer R a1 and the reflective layer R a2 The FP structure allows the distance between the substrate and the substrate or the refractive index to be changed. The gradient thickness spectral filter B has a reflective layer R b1 and the reflective layer R on the light exit side b2 It has a film thickness gradient FP structure in which the distance (thickness of the transparent medium) between the film and the substrate increases continuously in one direction. In the spectroscopic analysis device of the present invention, the imaging element, the tunable wavelength transmission optical filter A, and the gradient thickness spectral filter B are arranged so that a portion of incident light passes through both the tunable wavelength transmission optical filter A and the gradient thickness spectral filter B before reaching the imaging element, and the remaining incident light passes through the tunable wavelength transmission optical filter A but does not pass through the gradient thickness spectral filter B before reaching the imaging element. There is no limitation on the order in which a portion of the incident light passes through both the tunable wavelength transmission optical filter A and the gradient thickness spectral filter B, and the transmitted light through the tunable wavelength transmission optical filter A may be incident on the gradient thickness spectral filter B, or the transmitted light through the gradient thickness spectral filter B may be incident on the tunable wavelength transmission optical filter A. There is also no particular restriction on the location of the gradient thickness spectral filter B, but it is preferable to provide it on or near an end row of the imaging element so as not to interfere with imaging. Furthermore, two or more gradient thickness spectral filters B may be provided, rather than just one. In particular, providing them on both ends of the imaging element is desirable, since it makes it possible to detect any inclination of the transmission wavelength tunable optical filter A or the like.

[0019] The transmission wavelength tunable optical filter A has the reflective layer R a1 and the reflective layer R a2 While maintaining the parallel state with the reflective layer R a1 and the reflective layer R a2 By controlling the distance or refractive index to a desired level, the device functions as a wavelength-tunable optical filter that transmits light of a wavelength corresponding to the distance or refractive index and blocks light of other wavelengths.

[0020] In the spectroscopic analysis device of the present invention, the gradient thickness spectral filter B is a linear color filter provided to confirm whether the tunable transmission wavelength optical filter A functions as an optical filter that selectively transmits a desired wavelength. Therefore, the gradient thickness spectral filter B itself is not directly involved in spectroscopic analysis, but is a spectral filter for detecting whether the light transmitted through the tunable transmission wavelength optical filter A has a desired wavelength. As described above, the gradient thickness spectral filter B has a reflective layer R b1 and the reflective layer R on the light exit side b2 The film thickness is increased continuously in one direction, and the film functions as a linear color filter. The use of a film thickness gradient FP structure as a linear color filter is known, and details of the fabrication method thereof can be found in, for example, International Publication No. 2023 / 032146. Figure 6 shows a schematic diagram of the gradient thickness spectral filter B and the film formation principle of the gradient film. The gradient thickness spectral filter B in Figure 6 is shown mounted on an image sensor (13). The gradient thickness spectral filter B is also shown as an example of a FP structure consisting of a three-layer Ag-SiO2-Ag multilayer film. The gradient thickness spectral filter B is a gradient thickness film in which the thickness of the transparent SiO2 layer increases continuously in one direction (from left to right in Figure 6). This gradient thickness film can be fabricated by controlling the amount of sputtered atoms deposited by placing a shadow mask (11) above the substrate (12) during sputtering deposition of the SiO2 layer. For example, it has been reported that a gradient thickness spectral filter was formed using a 30 nm thick Ag film (reflective layer) and a gradient SiO2 film with thicknesses of 75 to 185 nm, resulting in a linear color filter with a spectral resolution of 15 nm and a wavelength range of 400 to 700 nm. As the thickness of the gradient thickness spectral filter B increases in one direction, the transmission peak wavelength shifts toward longer wavelengths.

[0021] In one form (referred to as "first form") of the spectroscopic analysis device of the present invention, the transmission peak wavelength of the gradient thickness spectral filter B, onto which a portion of the transmitted light of the tunable transmission wavelength optical filter A is incident, is used as an index for detecting whether or not the transmitted light of the tunable transmission wavelength optical filter A has a desired wavelength. In this case, the analysis device of the present invention can employ a structure in which, in a spectroscopic analysis device having the tunable transmission wavelength optical filter A and an imaging element that detects the light transmitted through the tunable transmission wavelength optical filter A, the gradient thickness spectral filter B is disposed somewhere between the imaging element and the tunable transmission wavelength optical filter A so that a portion of the transmitted light of the tunable transmission wavelength optical filter A is incident thereon.

[0022] 7 is an explanatory diagram (cross-sectional view) for explaining an example of the structure of the first embodiment of the spectroscopic analyzer of the present invention. Note that the drawings for explaining the present invention are schematic diagrams for facilitating understanding of the present invention, and the sizes or relative size relationships of the various components may be changed for the sake of explanation, and do not directly represent the actual relationships.

[0023] In the spectroscopic analyzer shown in Fig. 7, the transmission wavelength tunable optical filter A (21) is a so-called air-gap FP optical filter. This air-gap FP optical filter has two reflective layers R a1 and the reflective layer R a2 The reflective layer R has a silver alloy (Ag alloy) layer as a reflector, and the transparent medium between these reflective layers is air. a1 and the reflective layer R a2 are all disposed on an SiO2 substrate, and a reflective layer R a1 and the reflective layer R a2 The distance (air gap, arrow in the figure) between the reflecting layer R and the reflecting layer R is variable. a2 The reflective layer R of the SiO2 substrate a2The area where the gradient thickness spectral filter B (22) is arranged is preferably small so as not to interfere with the intended spectral analysis (it is arranged in a part of the depth direction in FIG. 7, see FIG. 8). The gradient thickness spectral filter B (22) is arranged on a part of the surface opposite to the reflective layer R. b1 and the reflective layer R b2 SiO2 is used as the transparent medium between the reflective layer R b1 and the reflective layer R b2 The spectroscopic analyzer shown in Figure 7 uses a CMOS sensor as the imaging element. A cover glass (24) is placed on the pixels (23) of the CMOS sensor, and an SiO2 substrate is placed on top of that. In Figure 7, incident light (25) enters from the top and passes through to the bottom. The light that has passed through both the tunable optical filter A and the gradient thickness spectral filter B is indicated by the black arrows.

[0024] Figure 8 shows the optical principle of the spectroscopic analyzer when the air-gap FP optical filter is driven. Most of the light incident on the air-gap FP optical filter from the top of Figure 8 passes wavelength-selectively only through the air-gap FP optical filter and reaches the CMOS sensor, but a portion also passes through gradient-thickness spectral filter B. Gradient-thickness spectral filter B transmits light of specific wavelengths selectively at its position in the gradient direction of the film thickness. The position on the CMOS sensor of the light with the peak transmission wavelength that passes through gradient-thickness spectral filter B and reaches the CMOS sensor (the position of the light transmitted through gradient-thickness spectral filter B that corresponds to the transmission position of gradient-thickness spectral filter B) and the corresponding peak transmission wavelength of gradient-thickness spectral filter B theoretically correspond one-to-one. Therefore, the peak transmission wavelength of the light transmitted through gradient-thickness spectral filter B can be determined based on the position on the CMOS sensor of the light with the peak transmission wavelength that passes through gradient-thickness spectral filter B and reaches the CMOS sensor. Furthermore, because the peak transmission wavelength of gradient-thickness spectral filter B theoretically matches the peak transmission wavelength of the air-gap FP optical filter, it is possible to directly detect the peak transmission wavelength of light actually transmitted through the air-gap FP optical filter. In this way, the transmission peak wavelength of the light that actually passed through the air-gap FP optical filter can be detected simply by detecting on the CMOS sensor the position of the light that passed through the gradient thickness spectral filter B. Therefore, a measuring device for detecting the wavelength of the transmitted light is not required, and the transmission peak wavelength of the actual transmitted light can be easily detected by, for example, borrowing part of the image sensor of a spectroscopic analyzer. FIG. 8(a) shows the air gap of the air gap FP optical filter when white light is incident. a1 and the reflective layer R a2Figure 8(b) shows the state when white light is incident, with the air gap of the air-gap FP optical filter being larger than that in Figure 8(a) to transmit medium-wavelength light, which then passes through the gradient-thickness spectral filter B and reaches the CMOS sensor, which is the image sensor. Figure 8(c) shows the state when white light is incident, with the air gap of the air-gap FP optical filter being larger than that in Figure 8(b) to transmit long-wavelength light, which then passes through the gradient-thickness spectral filter B and reaches the CMOS sensor, which is the image sensor. As shown in each figure, the position of the light passing through the gradient-thickness spectral filter B changes depending on the wavelength of the light passing through the air-gap FP optical filter. In each figure, 23 represents a pixel of the image sensor. The smaller the tilt angle of the gradient thickness spectral filter B, the more improved the spectral accuracy. The length of the direction in which the thickness of the gradient thickness spectral filter B changes and tilts is determined by the length of one side of the imaging area of ​​the image sensor, so the longer the angle, the smaller the tilt angle of the gradient thickness spectral filter, which is preferable.

[0025] In the first embodiment, as an example, referring to FIG. 7, a gradient thickness spectral filter B is formed by a reflective layer R a2 The reflective layer R of the SiO2 substrate a2 The gradient thickness spectral filter B is fixed to a part of the surface opposite to the reflective layer R. a2 The term "fixed on the imaging element" includes both a form in which the element is fixed in contact with the imaging element and a form in which the element is fixed to a substrate or the like disposed on the imaging element.

[0026] In another embodiment (referred to as "second embodiment") of the spectroscopic analysis device of the present invention, the positional relationship of the tunable transmission wavelength optical filter A and the gradient thickness spectral filter B with respect to the incident direction of light is reversed compared to the first embodiment. That is, a portion of the incident light is dispersed into wavelengths by the gradient thickness spectral filter B and transmitted, and the transmission peak wavelength of the tunable transmission wavelength optical filter A into which this dispersed transmitted light is incident is detected. In this case, the analysis device of the present invention is provided with the gradient thickness spectral filter B on the light incident side of the tunable transmission wavelength optical filter A and so as to cover a portion of the tunable transmission wavelength optical filter A in plan view. In this second configuration, most of the incident light passes wavelength-selectively only through the tunable transmission wavelength optical filter A and reaches the image sensor, but a portion of the incident light enters the gradient thickness spectral filter B, and the transmitted light separated by the gradient thickness spectral filter B enters the tunable transmission wavelength optical filter A. As described above, the gradient thickness spectral filter B transmits light of a specific wavelength selectively in the position in the gradient thickness direction. The position on the image sensor of light with a peak transmission wavelength that has passed through the gradient thickness spectral filter B and then the tunable transmission wavelength optical filter A, and the peak transmission wavelength of the gradient thickness spectral filter B corresponding to that position, theoretically have a one-to-one correspondence. Therefore, based on the position on the image sensor of light with a peak transmission wavelength that has passed through the gradient thickness spectral filter B and the tunable transmission wavelength optical filter A in this order and reached the image sensor, it is possible to directly detect the peak transmission wavelength of light that has passed through the gradient thickness spectral filter B and the tunable transmission wavelength optical filter A in this order and reached the image sensor, i.e., the peak transmission wavelength of light that actually passed through the tunable transmission wavelength optical filter A.

[0027] In either of the spectroscopic analyzers of the first and second embodiments described above, it is possible to directly detect the actual transmission peak wavelength of the transmission wavelength tunable optical filter A in spectroscopic analysis.

[0028] 7 and 8, the transmission wavelength tunable optical filter A is formed by using the reflective layer R a1 and the reflective layer R a2Although an example using an air-gap FP optical filter with an air layer between the reflective layer R and the reflective layer R is shown, the transmission wavelength tunable optical filter A is not limited to the air-gap FP optical filter. a1 and the reflective layer R a2 A liquid crystal layer FP optical filter can also be used, in which the transparent medium between the first and second electrodes is a liquid crystal layer.

[0029] When an air-gap FP optical filter is used as the transmission wavelength tunable optical filter A, the size of the air gap (the above-mentioned reflective layer R a1 and the reflective layer R a2 The peak transmission wavelength of the air-gap FP optical filter can be controlled by controlling the distance between the air gap and the filter, for example, using an electrostatic actuator. In this case, since there is a theoretical one-to-one correspondence between the size of the air gap and the peak transmission wavelength of the air-gap FP optical filter, the state of the air gap can be determined by detecting the peak transmission wavelength of the air-gap FP optical filter.

[0030] When a liquid crystal layer FP optical filter is used as the transmission wavelength tunable optical filter A, the refractive index of the liquid crystal layer can be controlled by controlling the orientation of the liquid crystal molecules with the level of applied voltage, and as a result, the transmission peak wavelength of the liquid crystal layer FP optical filter can be controlled. In this case, since there is a theoretical one-to-one correspondence between the orientation or refractive index of the liquid crystal molecules and the transmission peak wavelength of the liquid crystal layer FP optical filter, the refractive index of the liquid crystal layer can also be determined by detecting the transmission peak wavelength of the liquid crystal layer FP optical filter.

[0031] In this way, the spectroscopic analysis device of the present invention can detect the peak transmission wavelength of the transmission wavelength tunable optical filter A based on the position at which light of the peak transmission wavelength that has passed through both the transmission wavelength tunable optical filter A and the film thickness gradient spectral filter B reaches the imaging element, and based on this detected peak transmission wavelength, can detect the state of the air gap if the transmission wavelength tunable optical filter A is an air gap FP optical filter, or the refractive index of the liquid crystal layer if the transmission wavelength tunable optical filter A is a liquid crystal layer FP optical filter. As described above, the position where light of the peak transmission wavelength that has passed through both the tunable transmission wavelength optical filter A and the gradient thickness spectral filter B reaches the imaging element can be associated in advance with the size of the air gap of the air-gap FP optical filter, and this position can be associated in advance with the refractive index of the liquid crystal layer of the liquid crystal layer FP optical filter. Therefore, it is also possible to detect the size of the air gap of the air-gap FP optical filter and the refractive index of the liquid crystal layer of the liquid crystal layer FP optical filter from the position where light of the peak transmission wavelength that has passed through both the tunable transmission wavelength optical filter A and the gradient thickness spectral filter B reaches the imaging element. However, even in this case, the detected size of the air gap and the refractive index of the liquid crystal layer are closely related to the peak transmission wavelength that has passed through both the tunable transmission wavelength optical filter A and the gradient thickness spectral filter B. Therefore, in the present invention, the form of "detecting the peak transmission wavelength of the tunable transmission wavelength optical filter A" also includes the form of "detecting the peak transmission wavelength of the tunable transmission wavelength optical filter A."

[0032] The spectroscopic analysis device of the present invention is a spectroscopic analysis device that obtains the spectrum of an analyte using a transmission wavelength-tunable optical filter A, and as described above, can directly detect the actual transmission peak wavelength of the transmission wavelength-tunable optical filter A in spectroscopic analysis. Therefore, it becomes possible to calibrate the spectroscopic analysis device before spectroscopic analysis when the environment in which the spectroscopic analysis is performed (such as the installation location of the device) changes. It also becomes possible to check in real time the accuracy of the control of the transmission light wavelength by the transmission wavelength-tunable optical filter A during spectroscopic analysis.

[0033] The spectroscopic analyzer of the present invention is not particularly limited in wavelength range for spectroscopic analysis, and can be designed to perform spectroscopic analysis over a wide range from ultraviolet light to infrared light. It can also be designed to perform spectroscopic analysis over a specific, limited wavelength range. For example, the spectroscopic analyzer of the present invention can be designed to perform spectroscopic analysis over a wavelength range of at least 400 to 700 nm (visible light range). In this case, the gradient thickness spectral filter B can be configured to reflect the reflective layer R at least in the wavelength range of 400 to 700 nm. b1 and the reflective layer R b2 It is possible to provide a configuration in which light of a specific wavelength is transmitted selectively at a position in the film thickness gradient direction depending on the distance between the film and the target.

[0034] [Spectroscopy method] The spectroscopic analysis method of the present invention can be carried out using the spectroscopic analysis apparatus of the present invention described above. That is, in one embodiment, the spectroscopic analysis method of the present invention includes, when spectroscopically analyzing light incident on the transmission wavelength tunable optical filter A, making a portion of the transmitted light of the transmission wavelength tunable optical filter A incident on the film thickness gradient spectral filter B, and detecting the transmission peak wavelength of the transmission wavelength tunable optical filter A in the spectroscopic analysis using the transmission peak wavelength of the film thickness gradient spectral filter B as an index. In another aspect of the spectroscopic analysis method of the present invention, a portion of incident light is separated into wavelengths by the gradient thickness spectroscopic filter B and transmitted, and the peak transmission wavelength of the transmission wavelength-tunable optical filter A into which the separated transmitted light is incident is used as an index to detect the peak transmission wavelength of the transmission wavelength-tunable optical filter A in the spectroscopic analysis. In both of the above embodiments, the transmission peak wavelength of the transmission wavelength tunable optical filter A can be detected based on the position at which light of the transmission peak wavelength that has passed through both the transmission wavelength tunable optical filter A and the film thickness gradient spectral filter B reaches the imaging element.

[0035] An optical system equipped in a spectroscopic analysis device of the present invention was fabricated using an air-gap FP optical filter as the transmission wavelength tunable optical filter A, and its performance was verified, which will be described below as an example. Note that the following example does not use an imaging element, and is merely an experiment for verifying the principles of the optical system equipped in a spectroscopic analysis device of the present invention. The present invention should not be construed as being limited by the following example, except as defined in the present invention. [Example]

[0036] [Design of gradient thickness spectral filter B] In order to design a spectral filter B with a gradient thickness whose transmission characteristics change linearly in the visible light range, a reflective layer R made of an Ag alloy was b1 and the reflective layer R b2 The optical transmittance of the FP structure with SiO2 as the transparent medium layer was calculated using Rigorous Coupled Wave Analysis (RCWA). The calculation was performed using Diffract MOD, a calculation software from Synopsys. As a result, the reflective layer R b1 and the reflective layer R b2 When the thickness of the first layer was set to 30 nm and the thickness between the first layer and the second layer was set to 75 to 185 nm, it was found that the transmittance peak shifted in the wavelength range of 400 to 700 nm, as shown in FIG.

[0037] [Design of wavelength-tunable optical filter A] An air-gap FP optical filter was adopted as the transmission wavelength tunable optical filter A, and the size of the air gap (the reflective layer R a1 and the reflective layer R a2 We designed the distance between the As a result, the reflective layer R a1 and the reflective layer R a2 By forming a 30 nm thick Ag alloy and making the air gap movable in the range of 130 to 300 nm, it was found that the transmittance peak shifts in the wavelength range of 400 to 700 nm, as shown in Figure 10.

[0038] [Production of optical system for spectroscopic analysis equipment] Figure 11 shows a schematic cross section of the optical system of the designed spectroscopic analyzer. The upper substrate supporting the air-gap FP optical filter is a 0.5 mm thick SiO2 substrate, on which a 30 nm thick Ag alloy film (reflective layer R) with a 3 μm high protrusion is formed. a1 The lower substrate was a 2.0 mm thick SiO2 substrate, and a 30 nm thick Ag alloy film (reflective layer R a2 ) was deposited on the rear surface of the upper and lower substrates. The thickness of the upper and lower substrates may be thinner than that of the example, provided that the substrates do not warp. The gradient thickness spectral filter B designed above was then deposited on the rear surface. The deposition range (multilayer deposition area) for forming the gradient thickness spectral filter B was the entire area shown as 2.7 mm wide in Figure 12. However, for ease of explanation, Figure 11 omits the area other than the gradient (the area with a constant thickness) (the same applies to Figure 18, described below). A piezoelectric element (41, PA1CEW manufactured by THORLABS) was used to drive the air gap. The maximum displacement of this piezoelectric element was 2.0 μm, which is sufficient to drive the air gap of the air gap FP optical filter designed above, which is 130 to 300 nm. The piezoelectric element (41) and the lower substrate were fixed on a 0.5 mm thick SiO2 substrate, and the top surface of the piezoelectric element was fixed to the upper substrate. The piezoelectric element 41 was fixed using adhesive 42, and the lower substrate was fixed using carbon tape 43. The manufacturing process will be explained below.

[0039] <Reflection layer R a1 Fabrication of the upper board> Reflective layer R a1 The manufacturing process of the upper substrate will be described with reference to FIG.

[0040] (a) A photoresist (51, OFPR-800LB 200cp) was spin-coated at 3000 rpm for 20 seconds onto a SiO2 substrate measuring 20 mm in length, 20 mm in width, and 0.5 mm in thickness. (b) A 4.5 mm×3.5 mm photomask (not shown) was placed on the photoresist, and exposure was performed using a mask aligner MA6 manufactured by SUSS Microtec. (c) The photoresist was immersed in a solution containing 2.38 mass % of TMAH (tetramethylammonium hydroxide) for 150 seconds, and then developed by rinsing twice with pure water for 30 seconds each. (d) Elionix ion beam milling system EIS-220P, 1.02 mA / cm 2 The mixture was milled at RT for 75 minutes. (e) Piranha cleaning was performed to remove the resist. (f) Ag alloy (52, Ag purity 99.5%, Tanaka Kikinzoku Kogyo Co., Ltd.) was subjected to 1.47 mA / cm 2 The film was formed by sputtering for 5 minutes under Ar gas at 0.65 Pa. The sputtering rate of the Ag alloy was 6 nm / min, and an Ag alloy film with a thickness of 30 nm was formed.

[0041] <Reflection layer R a2 and fabrication of the lower substrate with gradient thickness spectral filter B> Reflective layer R a2 The manufacturing process of the lower substrate with the gradient thickness spectral filter B will be described with reference to Figures 14 and 15. Figure 14 is a top view of the lower substrate. Figure 15 is a cross-sectional view taken along the line A-A' in Figure 14. That is, Figure 15 shows cross sections of both the area masked with polyimide tape (61) during the process and the multilayer film formation area (62), divided into left and right sections.

[0042] (a) A polyimide tape (61) was attached to a SiO2 substrate having a length of 10 mm, a width of 10 mm and a thickness of 2.0 mm to form a mask, as shown in FIGS. (b) A 30-nm-thick Ag alloy (63, Ag purity 99.5%, manufactured by Tanaka Kikinzoku Kogyo Co., Ltd.) was sputtered at 83 W for 50 seconds in 0.6 Pa Ar gas. (c) A metal mask (64) was placed 2.0 mm away from the sample, and a SiO2 gradient film was sputtered using a Shibaura Mechatronics CFS-4ES to a maximum thickness of 190 nm. Sputtering was performed at 300 W for 23.5 seconds in 0.5 Pa Ar gas. (d) A 30 nm thick Ag alloy (63, Ag purity 99.5%, manufactured by Tanaka Kikinzoku Kogyo Co., Ltd.) was sputtered at 83 W for 50 seconds in 0.6 Pa Ar gas. (e) Using a Shibaura Mechatronics CFS-4ES, an 80 nm SiO2 film was sputtered. Sputtering was performed at 300 W for 10 seconds in 0.5 Pa Ar gas. (f) The polyimide tape was removed, and the sample was subjected to ultrasonic cleaning with acetone. (g) The bottom surface of the substrate (the side on which the gradient film was formed) was attached to a 0.5 mm thick SiO2 substrate (base substrate) using carbon tape (65). (h) An Elionix ECR ion beam sputtering system EIS-220P was used to sputter Ag alloy (63) to a thickness of 30 nm. The sputtering current was 1.47 mA / cm. 2 The treatment was carried out at 0.65 Pa of Ar gas for 5 minutes.

[0043] The reflective layer R that was created a2 Photographs of the lower substrate with gradient thickness spectral filter B taken after step (g) and before step (h) are shown in Figure 16. The rainbow-colored stripes in the center of Figure 16 are the sloped portions of gradient thickness spectral filter B (described as gradient thickness optical filter in Figure 16). In order to evaluate gradient thickness spectral filter B itself, after step (g) of the above manufacturing process, the reflective layer R a2 Before depositing the film, transmission microspectroscopy measurements were performed while moving the position on the gradient thickness spectral filter B in 0.25 mm increments. Figure 17 shows the relationship between the position x and the peak wavelength for positions x = 0.00 to 2.50 mm, which includes the peak wavelength range of 400 to 700 nm. Figure 17 shows that we were able to produce a gradient thickness spectral filter B with a filter length of 2.0 mm that covers the transmission peak wavelength range of 400 to 700 nm.

[0044] <Assembly of the optical system for spectroscopic analysis equipment> The assembly process of the filter using the fabricated upper and lower substrates and piezoelectric elements will be described with reference to FIG.

[0045] (a) The piezoelectric element was attached to the base substrate with cyanoacrylate adhesive. The piezoelectric element was attached at the reflective layer R. a2 The position was 1 mm away from the lower substrate with the gradient thickness spectral filter B. (b) A reflective layer R is applied to the top surface of the piezoelectric element with epoxy adhesive. a1 The upper board was placed on the board. (c) Under a microscope, the gradient portion of the film thickness gradient spectral filter B is aligned with the position where the transmitted light of the air gap FP optical filter is incident, and the reflective layer R a1 The upper substrate and the reflective layer R a2 The lower substrate with the gradient thickness spectral filter B was pressed against the substrate to make them parallel to each other. (d) Leave it for half a day to allow the epoxy adhesive to completely harden. In this way, the optical system of the spectroscopic analyzer was assembled.

[0046] <Verification of the optical system of a spectroscopic analyzer> To investigate whether the light transmitted through the air-gap FP optical filter can be dispersed by the gradient thickness spectral filter B, the transmission peak wavelengths of the area where the incident light passes only through the air-gap FP optical filter (single filter area) and the area where the incident light passes through the air-gap FP optical filter and the gradient thickness spectral filter in that order (double filter area) were measured by transmission microspectroscopy. Specifically, when the applied voltage to the piezoelectric element was 0.0V, transmission microspectroscopic measurements were performed in the single filter area (the area other than the multilayer film formation area in FIG. 16) at positions X of 0.00 mm, 0.25 mm, and 0.50 mm in FIG. 16. The average transmission peak wavelength at three locations was calculated to be 557.6 nm. Furthermore, when the applied voltage to the piezoelectric element was 5.0V, transmission microspectroscopic measurements were performed in the single filter area at positions X of 0.00 mm, 0.25 mm, and 0.50 mm in FIG. 16. The average transmission peak wavelength at three locations was calculated to be 589.3 nm. The difference between the two transmission peak wavelengths is 31.7 nm. Next, when the voltage applied to the piezoelectric element was 0.0 V, the peak transmission wavelength of light transmitted through gradient thickness spectral filter B in the double filter area was 550.2 nm. When the voltage applied to the piezoelectric element was 5.0 V, the peak transmission wavelength of light transmitted through gradient thickness spectral filter B in the double filter area was 580.6 nm. The difference between these peak transmission wavelengths is 30.4 nm.

[0047] As described above, when the voltage applied to the piezoelectric element was 0.0 V and 5.0 V, the peak transmission wavelength of the air-gap FP optical filter shifted by 31.7 nm, whereas the peak transmission wavelength in the double filter area also shifted by 30.4 nm, almost the same as 31.7 nm. This demonstrates that the peak transmission wavelength of the air-gap FP optical filter can be detected from the peak transmission wavelength of gradient thickness spectral filter B. Although the transmission peak wavelength of the air-gap FP optical filter and that of the double filter area differ slightly in absolute value (557.6 nm vs. 550.2 nm, and 589.3 nm vs. 580.6 nm), this difference is due to the positional accuracy of the transmission microspectroscopy measurement. If transmission microspectroscopy could be performed with finer positional increments, this difference would disappear, and the transmission peak wavelength of the air-gap FP optical filter and that of the double filter area would match.

[0048] As described above, it has been demonstrated that it is possible to construct an optical system in which incident light is wavelength-selectively transmitted through both the tunable transmission wavelength optical filter A and the gradient thickness spectral filter B, as per theory. Therefore, it can be seen that by using an imaging element such as a CMOS sensor or CCD image sensor as the photodetector element of the above optical system, the peak transmission wavelength of the tunable transmission wavelength optical filter A can be detected based on the position at which light of the peak transmission wavelength that has transmitted through both the tunable transmission wavelength optical filter A and the gradient thickness spectral filter B reaches the imaging element.

[0049] The spectroscopic analysis device of the present invention can be suitably used, for example, as a compact hyperspectral imaging device with improved wavelength resolution and spatial resolution. For example, it can be used as a portable compact spectroscopic analysis device. The spectroscopic analysis device of the present invention can also be incorporated into a smartphone, tablet, wristwatch, etc. [Explanation of symbols]

[0050] R reflective layer M transparent medium 1. Glass substrate 2, 52, 63 Ag alloy membrane 3 Electrostatic Actuator 4. Air gap 11, 64 Shadow Mask 12 PCB 13 Image sensor 21 Transmission wavelength tunable optical filter A 22 Thickness gradient spectral filter B 23 pixels 24 cover slips 25 Incident light 41 Piezo element 42 Adhesive 43, 65 Carbon tape 51 Photoresist 61 Polyimide tape 62 Multilayer film deposition area

Claims

1. The optical filter includes an image sensor, a tunable transmission wavelength optical filter A, and a gradient thickness spectral filter B. The transmission wavelength tunable optical filter A has a reflective layer R on the light incident side. ａ１ and the reflective layer R on the light exit side. ａ２ and are arranged in parallel, and the reflective layer R ａ１ and the reflective layer R ａ２ a Fabry-Perot structure in which the distance or the refractive index between the The gradient thickness spectral filter B has a reflective layer R ｂ１ and the reflective layer R on the light exit side. ｂ２ The film has a thickness gradient Fabry-Perot structure in which the distance between the film and the substrate is continuously increased in one direction. A spectroscopic analysis device configured such that a portion of incident light passes through both the tunable transmission wavelength optical filter A and the gradient thickness spectral filter B and reaches the image sensor, and the remaining incident light passes through the tunable transmission wavelength optical filter A but reaches the image sensor without passing through the gradient thickness spectral filter B.

2. using the transmission peak wavelength of the gradient thickness spectral filter B, into which a portion of the transmitted light of the transmission wavelength tunable optical filter A is incident, as an index, or A part of the incident light is separated into wavelengths by the gradient thickness spectral filter B and transmitted, and the transmission peak wavelength of the transmission wavelength tunable optical filter A into which the separated transmitted light is incident is used as an index, 2. The spectroscopic analysis device according to claim 1, wherein the spectroscopic analysis device detects a transmission peak wavelength of the transmission wavelength tunable optical filter A in spectroscopic analysis.

3. 3. The spectroscopic analysis device according to claim 2, wherein the peak transmission wavelength of the tunable optical filter A is detected based on a position at which light of the peak transmission wavelength that has passed through both the tunable optical filter A and the gradient thickness spectral filter B reaches the image sensor.

4. The reflective layer R ａ２ is disposed on the substrate a2, and the reflective layer R ａ２ 4. The spectroscopic analyzer according to claim 3, wherein the gradient thickness spectral filter B is disposed on a part of the surface opposite to the surface of the spectroscopic analyzer.

5. The spectroscopic analysis device according to claim 3 , wherein the gradient thickness spectral filter B is disposed on the image sensor.

6. The thickness gradient spectral filter B is configured to reflect the light emitted from the reflective layer R at least in the wavelength range of 400 to 700 nm. ｂ１ and the reflective layer R ｂ２ 4. The spectroscopic analyzer according to claim 3, wherein light of a specific wavelength is transmitted selectively at a position in a film thickness gradient direction depending on the distance between the film thickness gradient direction and the target.

7. The reflective layer R ｂ１ and the reflective layer R ｂ２ Between ２ The spectroscopic analyzer of claim 3 , wherein the spectroscopic analyzer is a layer.

8. The reflective layer R ａ１ and the reflective layer R ａ２ The spectroscopic analyzer according to claim 3 , wherein an air layer is provided between the

9. By detecting the transmission peak wavelength of the transmission wavelength tunable optical filter A, the reflection layer R ａ１ and the reflective layer R ａ２ The spectroscopic analyzer according to claim 8, wherein the spectroscopic analyzer detects a distance between the

10. The reflective layer R ａ１ and the reflective layer R ａ２ The spectroscopic analyzer according to claim 3 , wherein a liquid crystal layer is provided between the first and second electrodes.

11. The spectroscopic analyzer according to claim 10 , wherein the refractive index of the liquid crystal layer is detected by detecting the transmission peak wavelength of the transmission wavelength tunable optical filter A.

12. Reflective layer R on the light incident side ａ１ and the reflective layer R on the light exit side. ａ２ and are arranged in parallel, and the reflective layer R ａ１ and the reflective layer R ａ２ When a wavelength-tunable optical filter A having a Fabry-Perot structure in which the distance between the wavelength-tunable optical filter A and the refractive index thereof is variable is used to perform spectroscopic analysis of light incident on the wavelength-tunable optical filter A, Reflective layer R on the light incident side ｂ１ and the reflective layer R on the light exit side. ｂ２ A part of the transmitted light of the transmission wavelength tunable optical filter A is incident on a thickness gradient spectral filter B having a thickness gradient Fabry-Perot structure in which the distance between the thickness gradient spectral filter B and the optical filter A is continuously increased in one direction, and the transmission peak wavelength of the thickness gradient spectral filter B is used as an index, or A part of the incident light is separated into wavelengths by the gradient thickness spectral filter B and transmitted, and the separated transmitted light is incident on the transmission wavelength tunable optical filter A, and the transmission peak wavelength of the transmission wavelength tunable optical filter A is used as an index. a spectroscopic analysis method including detecting a transmission peak wavelength of the transmission wavelength tunable optical filter A in the spectroscopic analysis.

13. 13. The spectroscopic analysis method according to claim 12, wherein the peak transmission wavelength of the tunable optical filter A is detected based on a position at which light with a peak transmission wavelength that has passed through both the tunable optical filter A and the gradient thickness spectral filter B reaches the image sensor.

Images