Adjustable filter based on temperature change characteristics

Abstract

The invention provides an adjustable filter based on temperature change characteristics according to the problem of traditional filtering limitation, and relates to the technical field of filter design in imaging spectrometers. According to the adjustable filter provided by the invention, the temperature is taken as an independent variable, and the change of the transmissivity of the thermally induced phase change material in the phase change temperature interval is converted into the change of the transmission spectrum of the interference film along with the temperature, so that the adjustable function of the filter is realized. Through a temperature-transmissivity spectrum mapping relation, continuous spectrum tuning without mechanical motion and with low power consumption is realized, and an innovative filtering solution is provided for an imaging spectrometer. Meanwhile, the filter regulation and control function is achieved, meanwhile, the temperature change transmission spectrum characteristic meets the requirement of spectrograph inversion, that is, original data of spectrum inversion is provided for transmissivity spectrums at different temperatures, and therefore the invention further provides a spectrum inversion method. The method can be applied to the technical fields of environment monitoring, medical diagnosis, intelligent manufacturing and the like.

Description

Technical Field

[0001] The present invention relates to the technical field of filter design in imaging spectrometers, and particularly relates to a tunable filter based on temperature-variable characteristics. Background Art

[0002] As a core device for multi-dimensional optical information acquisition, the performance of an imaging spectrometer depends on the flexibility and accuracy of the front-end filtering system. Traditional filter lenses mostly use mechanically switched filters or liquid crystal / acousto-optic tunable filters, but there are the following limitations:

[0003] 1. Mechanical filter: Since it relies on physical displacement to switch the filter, it results in a large volume and a slow response speed (millisecond level), making it difficult to meet the requirements of high-speed dynamic scenarios (such as UAV remote sensing and industrial on-line detection).

[0004] 2. Liquid crystal / acousto-optic tunable filter: Since it requires complex drive circuits (such as high-frequency voltage or acoustic wave signals), it results in high power consumption and high cost, and the spectral tuning range is limited by materials (such as liquid crystals being insensitive to the infrared band).

[0005] Therefore, with the development of spectral imaging technology towards miniaturization, intelligence, and real-time, there is an urgent need for a filter design with low power consumption, fast response, and wide-band tunability to adapt to the requirements of high-dynamic and multi-scene applications. Summary of the Invention

[0006] The present invention proposes a tunable filter based on temperature-variable characteristics, which can be used as the front-end filtering system of an imaging spectrometer. By controlling the optical properties of thermally induced phase change materials through temperature, the tunable function of the filter is realized, that is, through the mapping relationship between the temperature-transmittance spectrum, continuous spectral tuning without mechanical movement and low power consumption is achieved, providing an innovative filtering solution for the imaging spectrometer.

[0007] To achieve the above object, the present invention provides the following technical solutions:

[0008] In order to realize the tunable function of the filter, the present invention proposes a tunable filter based on temperature-variable characteristics. The filter takes temperature as an independent variable, and transforms the change in the transmittance of thermally induced phase change materials in the phase change temperature range into the change in the interference film transmittance spectrum with temperature, thereby realizing the tunable function of the filter.

[0009] Furthermore, the above tunable filter includes an antireflection film, an F-P resonator, and a high refractive index material;

[0010] The upper and lower layers of the F-P resonator are respectively an antireflection film and a high refractive index material.

[0011] Furthermore, two layers of thermally induced phase change materials form the upper and lower transmission surfaces of the above F-P resonator, and the high refractive index material is the intermediate dielectric layer;

[0012] Furthermore, the antireflection film is formed by periodically stacking high- and low-refractive-index materials, and is used to increase the transmittance of incident light, reduce reflection, and prevent oxidation of the thermally induced phase change material during the phase change process.

[0013] Furthermore, by doping the thermally induced phase change material with W or Mo material, the phase change temperature of the thermally induced phase change material can be adjusted to room temperature.

[0014] The present invention also provides an imaging spectrometer, which is implemented based on the tunable filter with temperature-variable characteristics described in any one of the above, and the imaging spectrometer measures the transmitted light intensity signal in real time during the phase change process, and combines the temperature-variable transmittance spectrum of the interference film to invert the incident spectrum, so as to realize the function of the imaging spectrometer for measuring unknown incident spectra.

[0015] Furthermore, the imaging spectrometer specifically includes a light source module, a tunable filter, a temperature control module, a photodetector, and a host computer;

[0016] The light source module is used to vertically inject incident light into the tunable filter;

[0017] The temperature control module is used to control the phase change temperature of the tunable filter, so that the tunable filter adjusts the transmittance spectrum according to the temperature change;

[0018] The photodetector is used to collect the transmitted light intensity data passing through the tunable filter in real time during the temperature change process;

[0019] The host computer is used to perform inverse calculation on the incident spectrum according to the transmitted light intensity data and the temperature-variable transmittance spectrum of the interference film.

[0020] Furthermore, while the present invention realizes the filter regulation function, the temperature-variable transmittance spectrum characteristic meets the requirements of spectrometer inversion, that is, the transmittance spectra at different temperatures provide the original data for spectral inversion. Therefore, the present invention also provides a spectral inversion method, specifically:

[0021] Step S1: Control the temperature change of the thermally induced phase change material in the phase change temperature range to obtain a continuous transmittance spectrum data set;

[0022] Step S2: Obtain the transmitted light intensity of the external light source passing through the spectrometer;

[0023] Step S3: Solve the inverse matrix of the light intensity formula of the transmitted light intensity according to the transmittance spectrum data set, and inversely solve the spectral distribution of the incident light intensity.

[0024] Furthermore, the above inversion method can be stored in a storage system, and the storage system includes a storage device, and the storage device is used to execute the above spectral inversion method.

[0025] The spectral inversion method described in the present invention can be entirely implemented by computer software. Correspondingly, the present invention also provides a computer-readable storage medium, on which a computer program is stored. When the computer program is run by a processor, the above-mentioned spectral inversion method is executed.

[0026] The present invention also provides a computer device, which includes a memory and a processor. A computer program is stored in the memory. When the processor runs the computer program stored in the memory, the processor executes the spectral inversion method of any one of the above.

[0027] The beneficial effects of the present invention are as follows:

[0028] 1. In view of the limitations of traditional filtering, the present invention proposes an adjustable filter based on temperature-variable characteristics. By controlling the optical properties of thermally induced phase change materials through temperature, and then designing it into the regulation function of the filter, that is, through the mapping relationship between the temperature-transmittance spectrum, continuous spectral tuning without mechanical movement and low power consumption is achieved, providing an innovative filtering solution for imaging spectrometers.

[0029] Furthermore, the phase change process of the thermally induced phase change material proposed in the present invention is a solid-solid phase change, without mechanical movement or complex driving. Only a small amount of temperature control energy (such as a micro heater) is required, and the response speed can reach the microsecond level, thus realizing the fast response and low power consumption of the adjustable filter.

[0030] Furthermore, by adjusting conditions such as the selection of dielectric layer materials and the design of film layer structure parameters, the present invention can realize the design of filters in any working band.

[0031] Furthermore, while realizing the filtering function, the temperature-variable transmittance spectrum characteristics of the present invention meet the requirements of inverse transformation spectrometers. Therefore, the present invention further realizes the second function: spectral inversion. That is, temperature regulation makes the filter have different filtering characteristics (transmittance spectrum) at different temperatures, and the transmittance spectra at different temperatures provide the original data for spectral inversion.

[0032] 2. The adjustable filter based on temperature-variable characteristics proposed in the present invention can be used as a filtering system at the front end of an imaging spectrometer. In the optical path design, it can be directly vertically incident on the interference film, and an anti-reflection film structure is provided on the surface of the interference film to suppress reflection and allow more light to pass through the film, thereby increasing the output signal intensity. At the same time, the interference film layer has temperature-variable transmittance characteristics in the visible to mid-infrared bands, breaking through the band limitations of traditional adjustable filters, and having higher inversion accuracy and a wider working band.

[0033] 3. By breaking through the bottleneck of traditional filtering technology, the present invention promotes the evolution of imaging spectrometers towards lower costs and higher adaptability, and helps with technological upgrades in fields such as smart cities, precision medicine, and Industry 4.0.

[0034] The present invention can be applied to technical fields such as environmental monitoring, medical diagnosis, and intelligent manufacturing. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] In order to more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the following will briefly introduce the drawings required for use in the description of the specific embodiments or the prior art. Obviously, the drawings in the following description are some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0036] Figure 1 is a schematic structural diagram of an adjustable filter based on temperature-variable characteristics proposed by the present invention;

[0037] Figure 2 is a structural form of the temperature-variable adjustable filter proposed by the present invention;

[0038] Figure 3 is the transmission spectrum passing through the temperature-variable adjustable filter described in the present invention;

[0039] Figure 4 is the sine spectrum inversion situation described in the present invention;

[0040] Figure 5 is the random spectrum inversion situation described in the present invention;

[0041] Figure 6 is the quasi-monochromatic light (256 nm bandwidth) inversion situation described in the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0042] The following further details the specific embodiments of the present invention in conjunction with the drawings. The following embodiments will help those skilled in the art to further understand the present invention, but do not limit the present invention in any form. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present invention, several changes and improvements can still be made, and these all fall within the protection scope of the present invention.

[0043] Embodiment 1. To solve the limitations of traditional filtering devices, an adjustable filter based on temperature-variable characteristics is proposed in this embodiment. The filter takes temperature as the independent variable, converts the change in the transmittance of the thermally induced phase change material in the phase change temperature range into the change in the transmission spectrum of the interference film with temperature, and realizes the adjustable function of the filter.

[0044] An adjustable filter based on temperature-variable characteristics proposed in this embodiment controls the optical properties of thermally induced phase change materials through temperature, and then designs its regulation function as a filter, that is, through the mapping relationship between temperature-transmittance spectra, continuous spectral tuning without mechanical movement and low power consumption is achieved, providing an innovative filtering solution for imaging spectrometers.

[0045] The design of the adjustable filter based on temperature-variable characteristics proposed in this embodiment can be widely applied to:

[0046] Environmental monitoring: Real-time inversion of the characteristic spectra of atmospheric components (such as CO 2 , CH 4 ) to improve the efficiency of pollution source tracking.

[0047] Medical diagnosis: Rapid identification of the characteristic spectra of tissue hemoglobin and cancer cells in a portable spectrometer.

[0048] Intelligent manufacturing: Online spectral analysis of material components in industrial production lines to replace traditional laboratory testing.

[0049] Embodiment 2: This embodiment gives an example of the structure of the adjustable filter based on temperature-variable characteristics proposed in the above Embodiment 1;

[0050] As Figure 1 shown, the adjustable filter includes an antireflection film, an F-P resonator, and a high-refractive-index material;

[0051] The upper and lower layers of the F-P resonator are an antireflection film and a high-refractive-index material respectively.

[0052] Among them, the F-P resonator is composed of two layers of thermally induced phase change materials to form the upper and lower transmission surfaces of the resonator, and the high-refractive-index material is the intermediate dielectric layer; the antireflection film is formed by periodically stacking high- and low-refractive-index materials, which is used to improve the transmittance of incident light, anti-reflection, and prevent oxidation of thermally induced phase change materials during the phase change process. Its design principle is as follows: Considering the slow oxidation of thermally induced phase change materials and air, an anti-oxidation layer needs to be added to its surface. However, a general film structure will inevitably cause some reflection losses (which can be analyzed according to the Fresnel equation). Therefore, in this embodiment of the structural design, an antireflection film is selected to act as an anti-oxidation layer. On the one hand, it achieves the purpose of isolating air to prevent oxidation, and on the other hand, the antireflection film itself is used to reduce the reflectivity in the designed wavelength band, thereby reducing the light loss caused by reflection. The selection of the high-refractive-index material at the bottom of the adjustable filter is to ensure the normal incidence and transmission of incident light in the film structure. Since the working wavelength band given in this example is a wide wavelength band range of 1 to 14 microns, the material selection criteria for the antireflection film and the oxidation protection film are high refractive index (to ensure light transmission) and no or very little absorption of the radiation energy in this wavelength band (to ensure that there is no excessive meaningless loss of transmitted radiation).

[0053] Furthermore, by doping the thermally induced phase change material with W or Mo materials, the phase change temperature of the thermally induced phase change material can be adjusted to near room temperature to adapt to the actual working environment.

[0054] Embodiment 3. Refer to Figure 3 To illustrate this embodiment, this embodiment verifies and explains the transmittance control of the tunable filter based on the temperature change characteristics proposed in the above embodiment;

[0055] Through the transmission matrix programming simulation, several resonance peaks can be observed in the transmittance image in the 1-14um band, as Figure 3 shown. It can be seen from the figure that as the temperature increases, the wavelength corresponding to the peak and valley (spectral absorption peak) of the transmission spectrum shifts significantly, while the resonance peak shifts slightly. And the wavelengths corresponding to the peaks of the three absorption peaks shift significantly during the temperature increase process, and the valleys in the corresponding transmittance image also change accordingly. It can also be seen that in the phase change temperature range, the transmittance is controlled between 0.84 and 0.3 in the 5500-6300nm band, and the transmittance is controlled between 0.84 and 0.2 in the 8000-10000nm band. Thus, it can be known that the temperature-variable tunable filter achieves the effect of transmittance control in different wavelength ranges in the phase change temperature range.

[0056] Embodiment 4. The tunable filter based on the temperature change characteristics proposed in the above embodiment is used as the filtering system of the imaging spectrometer. Therefore, this embodiment proposes an imaging spectrometer. The imaging spectrometer realizes the function of measuring the unknown incident spectrum by measuring the transmitted light intensity signal in real time during the phase change process and combining the temperature-variable transmittance spectrum of the interference film to invert the incident spectrum.

[0057] Embodiment 5. This embodiment gives an example of the imaging spectrometer proposed in the above Embodiment 4; the imaging spectrometer includes a light source module, a tunable filter, a temperature control module, a photodetector, and a host computer;

[0058] The light source module is used to vertically inject incident light into the tunable filter;

[0059] The temperature control module is used to control the phase change temperature of the tunable filter so that the tunable filter adjusts the transmittance spectrum according to the temperature change;

[0060] The photodetector is used to collect the transmitted light intensity data passing through the tunable filter in real time during the temperature change process;

[0061] The host computer is used to perform inversion calculation on the incident spectrum according to the transmitted light intensity data and the temperature-variable transmittance spectrum of the interference film.

[0062] When this embodiment is actually applied, such as Figure 1As shown, the light source to be detected is vertically incident on the temperature-variable filter by using a light source module or other light source bodies; the phase transition temperature of the temperature-variable filter is adjusted by a temperature control module, so that in the phase transition temperature region, the optical properties of the thermally induced phase change material are controlled by temperature, and then the regulation function of the filter is realized, that is, the traditional moving mirror regulation is replaced by thermally induced phase change regulation, realizing the miniaturization of the spectrometer; further, by collecting the transmitted light intensity of the incident light source through the temperature-variable filter and combining the temperature-variable transmittance spectrum of the interference film in the phase transition temperature range to invert the incident spectrum, the function of the imaging spectrometer for measuring unknown incident spectra is realized.

[0063] Embodiment 6. While realizing the regulation function of the filter, the temperature-variable transmittance spectrum characteristics of the above embodiments meet the requirements of the inverse transformation spectrometer, that is, temperature regulation enables the filter to have different filtering characteristics (transmittance spectrum) at different temperatures, and the transmittance spectra at different temperatures provide the original data for spectral inversion. Therefore, this embodiment proposes a spectral inversion method, specifically:

[0064] Step S1: Control the temperature change of the thermally induced phase change material in the phase transition temperature range to obtain a continuous transmittance spectrum data set;

[0065] Step S2: Obtain the transmitted light intensity of the external light source through the spectrometer;

[0066] Step S3: Solve the inverse matrix of the light intensity formula of the transmitted light intensity according to the transmittance spectrum data set, and inversely solve the spectral distribution of the incident light intensity.

[0067] In the actual application of this embodiment, through the optimized design of the resonant cavity device, continuous transmittance data varying with temperature can be obtained, as Figure 3 shown, and the transmittance spectra at different temperatures provide the original data for spectral inversion. Therefore, the transmitted light intensity of the external light source through the resonant cavity device can be measured by the corresponding optical element. By solving the inverse matrix of the transmitted light intensity formula, the spectral distribution of the external light intensity can be inversely solved. That is, the original data set required for calculating spectral inversion is obtained by controlling the temperature of the resonant cavity device, realizing the inversion of the unknown incident spectral distribution.

[0068] Compared with the traditional spectrometer that directly measures the intensity of each wavelength, the imaging spectrometer measures the light intensity signal after being processed by the interference film, that is, the encoded version spectrum. By regulating the transmission spectrum of the interference film, the measured transmitted light intensity signal changes accordingly, and then it can be calculated and decoded, that is, the incident spectrum inversion calculation.

[0069]

[0070] where λ is the wavelength, I T(T) is the transmitted light intensity measured as a function of temperature during the phase change process, t(T,λ) is the temperature-dependent transmittance spectrum of the interference film, and I 0 (λ) is the unknown incident light spectrum to be measured. It can also be written in matrix form:

[0071] b = M × A

[0072] where A represents a one-dimensional column vector of n spectral channels of the input signal, and the a-th element A(a) represents the intensity of the wavelength λa in the incident light source; b represents a one-dimensional vector of m temperature channels of the output signal, which actually represents the real-time measurement of the transmitted light intensity during the phase change process; M represents the temperature-dependent transmittance spectrum data of the interference film designed according to the working requirements. Since the design parameters of the interference film are known, that is, the coefficient matrix M is known. When the incident light of an unknown spectrum is incident into the spectral transformation spectrometer system, the detector collects the real-time signal of the transmitted light intensity changing with temperature during the phase change process, so b is also known. Therefore, spectral inversion is to calculate A based on M and b.

[0073] Considering that there may be a situation where the linear correlation of some bands in the results of the transmitted spectrum at adjacent temperatures is too strong, which easily causes the condition number of the coefficient matrix of the inversion equation to be too large, resulting in the solution equation being ill-conditioned and unable to obtain accurate incident light intensity results. Therefore, in programming, the method of singular value decomposition (SVD) and deleting the minimum singular values is used to reduce the ill-conditioning degree of the inversion equation. The core is to express the coefficient matrix M representing the temperature-dependent transmittance spectrum as the operation of the product of the following three real matrices, that is, to perform matrix factorization:

[0074] M = U∑V T

[0075] where U is an m-order orthogonal matrix, V is an n-order orthogonal matrix, and ∑ is an m×n rectangular diagonal matrix composed of non-negative diagonal elements arranged in descending order.

[0076] Embodiment 7. Refer to Figures 4 to 6 To illustrate this embodiment, this embodiment is to verify and explain the spectral inversion effect proposed in the above Embodiment 6;

[0077] Under the action of temperature, the phase change of the thermochromic phase change material (vanadium dioxide) causes the change of the transmission spectrum of the filtering device, so as to obtain the transmitted light intensity data at different temperature nodes in the phase change temperature range (65 - 70 °C), and use it as the original data for the inversion calculation of the characteristics of the unknown incident spectrum.

[0078] In the inversion calculation of the incident light intensity, this embodiment adopts the method of matrix inverse operation, where the spectral transmittance of the device and the measured transmitted light intensity are used as known parameters to solve for the incident light intensity. By interpolating the optical parameters of vanadium dioxide in the phase change temperature range and selecting an interval of 0.05 °C, 101 sets of original parameters are obtained. The transmission spectrum [t(λ,T)] at the corresponding temperature can be obtained through simulation by the transfer matrix method, and the incident light intensity [IR(T)] can be measured by corresponding optical measurement elements in practical applications. In the calculation of the inversion program, this embodiment calculates the transmitted light intensity by a formula assuming the incident light intensity and uses it as an input parameter to study the error accuracy of true value inversion when performing matrix inverse operation.

[0079] This embodiment selects the 1-14 μm band for the inversion of the incident light intensity to verify the influence of the selected working band and the band corresponding to the transmission peak on the error. This embodiment analyzes the inversion results using two types of incident light, namely, a sine light source and a random light source, as Figure 4 and Figure 5 shown. It can be found that after eliminating the influence of linear correlation at the transmission peak position, the inversion error is greatly reduced, and the relative error is generally less than 0.1% in this band, enabling a good inversion effect of the incident light intensity and a high accuracy of true value inversion of the incident spectrum.

[0080] In addition, this embodiment also conducts relevant analysis on the inversion effect of quasi-monochromatic light, as Figure 6 shown. The results show that the spectral resolution of this embodiment is 128 nm in the 1-14 μm working band, and at the same time, the inversion accuracy for quasi-monochromatic light with a bandwidth of 256 nm is relatively high, showing superiority in performance.

[0081] Furthermore, through the analysis of the existing reflective spectral inversion, it can be seen that when performing spectral inversion, a certain incident angle is required for the detection of unknown incident light sources in order to design the optical path. According to the Fresnel reflection equation, the introduction of the incident angle will inevitably increase the reflectivity of the incident light (i.e., the part of the light refracted into the interference film becomes less), which will slow down the change trend of the reflected light intensity signal with temperature and affect the inversion of the subsequent unknown incident spectrum. Theoretically, the larger the incident angle, the greater the impact on the inversion accuracy. The transmissive spectral inversion proposed in this embodiment has obvious advantages compared with the reflective spectral inversion, mainly reflected in higher inversion accuracy and a wider working wavelength range. Due to the relatively high reflectivity of the reflective spectral inversion itself, part of the radiation does not enter the interference film structure for temperature regulation, thus affecting the inversion accuracy of the temperature-variable reflectivity spectrum. In addition, the inversion effect of the reflective spectral inversion is too poor in some wavelength bands, resulting in limitations in the selection of the working wavelength band and being unable to select a wider working wavelength band. The transmissive spectral inversion proposed in this embodiment does not need to consider the unregulated partial reflected radiation because the transmitted light must be temperature-regulated by the interference film, which is the reason for its high inversion accuracy and wide working wavelength band.

[0082] The Fresnel reflection equation is specifically as follows:

[0083] S polarization

[0084] P polarization

[0085] Among them, the incident angle: the angle between the incident light and the interface normal, denoted as θ i ; the refraction angle: the angle between the refracted light and the interface normal, denoted as θ t ; the refractive index: the medium on the incident side is n 1 , and the medium on the transmission side is n t .

[0086] Embodiment 8. This embodiment is an example of an adjustable filter based on the temperature-variable characteristics described in the above embodiment;

[0087] Based on the design concept of thermally induced phase change, by adjusting conditions such as the selection of the dielectric layer material and the design of the film layer structure parameters, an adjustable filter design for any working wavelength band can be achieved.

[0088] For example:

[0089] This filter utilizes the thermally induced phase change characteristics of vanadium dioxide to achieve the adjustable function of the filter through temperature. Considering the absorption of mid- and far-infrared light by some materials, such as Figure 2As shown, in this embodiment, ZnSe and Si are selected as infrared window materials for design: Si and ZnSe have the characteristics of high transparency and low absorption rate in the mid- and far-infrared bands. Using them as the dielectric layer materials of the interference film and studying the performance of the temperature-controlled spectrometer with the interference film structure in the mid- and far-infrared. The temperature-variable filtering device consists of two parts: 1. The antireflection film, which is composed of periodically stacked high- and low-refractive-index materials. Specifically, it is: 86nm ZnSe / 130nm Si / 86nm ZnSe, which plays the role of improving the transmittance of incident light, antireflection, and preventing oxidation during the phase change of vanadium dioxide VO 2 during the phase change process; 2. The F-P resonator, specifically: 20nm VO 2 / 3μm ZnSe / 20nm VO 2 / 100nm ZnSe. Two layers of vanadium dioxide VO 2 constitute the upper and lower transmission surfaces of the resonator, and ZnSe is the intermediate dielectric layer. Since vanadium dioxide VO 2 itself has strong absorption in the infrared band, therefore, in the design of the film layer structure, the comprehensive influence of the thickness of the vanadium dioxide film layer and the thickness of the dielectric layer should be considered. Compared with the reflective film layer, the significant difference of the present invention is the double-layer resonance design of vanadium dioxide VO 2 , that is, two layers of vanadium dioxide are used together in the film layer structure to regulate the transmittance spectrum of the resonator. The F-P resonator has the characteristics of a wide working range and can be designed for multiple wavelength analyses; at the same time, its simple structure is also convenient for device processing.

[0090] Furthermore, for the F-P resonator designed in this embodiment, with temperature as the independent variable, the change in the transmittance of vanadium dioxide in the phase change temperature range is converted into the optical path difference / phase difference of incident light interference, realizing the regulation of incident light interference, and thus realizing the adjustable function of the filter.

[0091] Furthermore, the above-mentioned vanadium dioxide (VO 2 ) is an intelligent material with insulator-metal phase change characteristics, and its optical transmittance changes significantly with temperature: its phase change temperature (~68℃) can be regulated: by doping (such as W, Mo), the phase change temperature can be adjusted to near room temperature to adapt to the actual working environment. Since the phase change process is a solid-solid phase change, no mechanical movement or complex drive is required, only a small amount of temperature control energy (such as a micro heater) is needed, and the response speed reaches the microsecond level. At the same time, the VO 2 film layer has the temperature-variable transmittance characteristics in the visible light to mid-infrared bands, breaking through the band limit of traditional tunable filters.

[0092] Furthermore, traditional spectral inversion relies on complex spectroscopic elements (such as gratings, prisms) or multi-channel filtering systems, resulting in large equipment volume and high cost. The temperature-variable characteristic (VO 2) The innovative design of the tunable filter can simplify the system and improve performance through the following paths:

[0093] Single filter multi-spectral detection: Utilize the VO 2 Characteristic that the transmittance spectrum changes continuously with temperature. Through dynamic temperature control + transmission signal acquisition, a single filter can cover the functions of multiple wavelength channels, significantly reducing the hardware complexity.

[0094] This technology proposed in this embodiment is particularly applicable to micro spectrometers (such as integrated with smartphones), spaceborne / airborne remote sensing platforms, and industrial on-line detection equipment, meeting the requirements of lightweight, low power consumption, and real-time analysis.

[0095] Embodiment Nine: The spectral inversion method proposed in the above embodiments can all be implemented by computer software. Therefore, correspondingly, this embodiment provides a computer-readable storage medium. A computer program is stored on this computer-readable storage medium, and when this computer program is run by a processor, it executes the spectral inversion method described above.

[0096] Embodiment Ten: This embodiment provides a computer device. This device includes a memory and a processor. A computer program is stored in the memory. When the processor runs the computer program stored in the memory, the processor executes the spectral inversion method described in any one of the above.

[0097] The hardware device of this part of the computer device provided in this embodiment is of a general model and is not shown in the form of a diagram. This system includes a processor and a memory. The processor and the memory can be connected through a bus or other means. The memory, as a non-transitory computer-readable storage medium, can be used to store non-transitory software programs, non-transitory computer-executable programs, and modules, as well as corresponding program instructions / modules. The processor runs the non-transitory software programs, instructions, and modules stored in the memory, thereby executing various functional applications and data processing of the processor to implement the spectral inversion method and steps in the above method embodiments.

[0098] In the description of this specification, a thermally induced phase change material refers to a substance whose optical properties change significantly with temperature. It has the following characteristics: (1) Phase reversibility. The amorphous state can be transformed into the crystalline state under the action of thermal energy or solar energy, and the crystalline state can also be transformed into the amorphous state by quenching or cooling. The conversion between the crystalline state and the amorphous state, as well as the degree of crystallization, can all reflect the change in the effective dielectric constant of the substance itself; (2) Any intermediate phase state can be obtained. Usually, by heating for different times at the same heating temperature or applying different heating temperatures at the same heating time, the required intermediate phase state can be obtained; (3) Stability, that is, most phase change materials can ensure that they are not easily volatilized or oxidized by air at room temperature in any phase state; (4) Fast response characteristics. There are many types of excitation sources for phase change materials, but the phase change response speed is very fast. By utilizing the properties of thermally induced phase change, in the phase change temperature region, the optical properties of the material can be controlled by temperature, and then it can be designed into the regulation function of a spectrometer.

[0099] The above are only the embodiments of the present invention and do not limit the present invention. For those skilled in the art, the present invention can have various changes and modifications. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included within the scope of the claims of the present invention.

Claims

1. A tunable filter based on temperature variation characteristics, characterized in that: The filter uses temperature as an independent variable, converts the change in transmittance of the thermotropic phase change material in the phase change temperature range into the change in the transmission spectrum of the interference film with temperature, thereby realizing the adjustable function of the filter.

2. The tunable filter based on temperature variation characteristics according to claim 1, characterized in that: The tunable filter includes an anti-reflection film, a FP resonant cavity and a high refractive index material; The upper and lower layers of the FP resonant cavity are anti-reflection film and high refractive index material respectively.

3. The tunable filter based on temperature variation characteristics according to claim 2, characterized in that: Two layers of thermotropic phase change material constitute the upper and lower transmission surfaces of the FP resonant cavity, and the high refractive index material is the middle dielectric layer; The anti-reflection film is formed by periodically stacking high and low refractive index materials, and is used to improve the transmittance of incident light, resist reflection, and prevent the thermoinduced phase change material from being oxidized during the phase change process.

4. The tunable filter based on temperature variation characteristics according to claim 1, characterized in that: By doping W or Mo materials into the thermotropic phase change material, the phase transition temperature of the thermotropic phase change material can be adjusted to room temperature.

5. The imaging spectrometer implemented by the tunable filter based on temperature-dependent characteristics according to any one of claims 1 to 4, characterized in that: By real-time measuring the transmitted light intensity signal during the phase change process and inverting the incident spectrum in combination with the temperature-dependent transmittance spectrum of the interference film, the imaging spectrometer can realize the function of measuring unknown incident spectra.

6. The imaging spectrometer according to claim 5, characterized in that: The imaging spectrometer includes a light source module, an adjustable filter, a temperature control module, a photodetector and a host computer; The light source module is used to vertically inject incident light into the tunable filter; The temperature control module is used to control the phase change temperature of the tunable filter so that the tunable filter can adjust the transmittance spectrum according to the temperature change; The photoelectric detector is used to collect the intensity data of the transmitted light through the adjustable filter in real time during the temperature change process; The host computer is used to perform inversion calculation on the incident spectrum based on the transmitted light intensity data and the temperature-dependent transmittance spectrum of the interference film.

7. The spectral inversion method implemented by the imaging spectrometer according to claim 5, characterized in that: The method is: S1: Control the temperature change of the thermotropic phase change material in the phase change temperature range to obtain a continuous transmittance spectrum data set; S2: Obtain the transmitted light intensity of the external light source through the spectrometer; S3: Solve the light intensity formula of the transmitted light intensity by inverse matrix according to the transmittance spectral data set, and invert and solve the spectral distribution of the incident light intensity.

8. The spectral inversion method according to claim 7 is characterized in that: The inversion method is stored in a storage system, and the storage system includes a storage device, and the storage device is used to execute the spectral inversion method described in claim 7.

9. A computer-readable storage medium, characterized in that: The computer-readable storage medium stores a computer program, and when the computer program is executed by a processor, the spectral inversion method according to claim 7 is executed.

10. A computer device, characterized in that: The device comprises a memory and a processor, wherein a computer program is stored in the memory, and when the processor runs the computer program stored in the memory, the processor executes the spectral inversion method according to claim 7.

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