CN113280915B - Fourier transform spectrometer and spectrum reconstruction method - Google Patents
Fourier transform spectrometer and spectrum reconstruction method Download PDFInfo
- Publication number
- CN113280915B CN113280915B CN202110603234.5A CN202110603234A CN113280915B CN 113280915 B CN113280915 B CN 113280915B CN 202110603234 A CN202110603234 A CN 202110603234A CN 113280915 B CN113280915 B CN 113280915B
- Authority
- CN
- China
- Prior art keywords
- spectrum
- blazed grating
- band
- light
- interference
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Active
Links
- 238000001228 spectrum Methods 0.000 title claims abstract description 64
- 238000000034 method Methods 0.000 title claims abstract description 19
- 238000005070 sampling Methods 0.000 claims abstract description 24
- 239000006185 dispersion Substances 0.000 claims abstract description 13
- 230000008878 coupling Effects 0.000 claims abstract description 3
- 238000010168 coupling process Methods 0.000 claims abstract description 3
- 238000005859 coupling reaction Methods 0.000 claims abstract description 3
- 230000003595 spectral effect Effects 0.000 claims description 76
- 230000003287 optical effect Effects 0.000 claims description 18
- 230000009977 dual effect Effects 0.000 claims description 6
- 230000005540 biological transmission Effects 0.000 claims description 5
- 230000001360 synchronised effect Effects 0.000 claims description 3
- 238000006243 chemical reaction Methods 0.000 claims description 2
- 238000001914 filtration Methods 0.000 claims description 2
- 238000006073 displacement reaction Methods 0.000 abstract 1
- 238000010586 diagram Methods 0.000 description 9
- 238000009826 distribution Methods 0.000 description 9
- 238000001514 detection method Methods 0.000 description 7
- 238000005516 engineering process Methods 0.000 description 6
- 239000000463 material Substances 0.000 description 5
- 238000005259 measurement Methods 0.000 description 5
- 238000002329 infrared spectrum Methods 0.000 description 4
- 238000004519 manufacturing process Methods 0.000 description 4
- 230000004907 flux Effects 0.000 description 3
- 230000008569 process Effects 0.000 description 3
- 239000000758 substrate Substances 0.000 description 3
- 238000011161 development Methods 0.000 description 2
- 230000018109 developmental process Effects 0.000 description 2
- 230000007613 environmental effect Effects 0.000 description 2
- 230000007246 mechanism Effects 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 238000012544 monitoring process Methods 0.000 description 2
- 238000005057 refrigeration Methods 0.000 description 2
- 230000011218 segmentation Effects 0.000 description 2
- 230000003068 static effect Effects 0.000 description 2
- 238000005033 Fourier transform infrared spectroscopy Methods 0.000 description 1
- 238000004566 IR spectroscopy Methods 0.000 description 1
- 230000004075 alteration Effects 0.000 description 1
- 238000004458 analytical method Methods 0.000 description 1
- 238000012937 correction Methods 0.000 description 1
- 230000001419 dependent effect Effects 0.000 description 1
- 239000003814 drug Substances 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 239000011521 glass Substances 0.000 description 1
- 239000002184 metal Substances 0.000 description 1
- 239000007769 metal material Substances 0.000 description 1
- 238000002360 preparation method Methods 0.000 description 1
- 238000006467 substitution reaction Methods 0.000 description 1
Images
Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01J—MEASUREMENT OF INTENSITY, VELOCITY, SPECTRAL CONTENT, POLARISATION, PHASE OR PULSE CHARACTERISTICS OF INFRARED, VISIBLE OR ULTRAVIOLET LIGHT; COLORIMETRY; RADIATION PYROMETRY
- G01J3/00—Spectrometry; Spectrophotometry; Monochromators; Measuring colours
- G01J3/02—Details
- G01J3/0205—Optical elements not provided otherwise, e.g. optical manifolds, diffusers, windows
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
- G01N21/01—Arrangements or apparatus for facilitating the optical investigation
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
- G01N21/17—Systems in which incident light is modified in accordance with the properties of the material investigated
- G01N21/25—Colour; Spectral properties, i.e. comparison of effect of material on the light at two or more different wavelengths or wavelength bands
- G01N21/31—Investigating relative effect of material at wavelengths characteristic of specific elements or molecules, e.g. atomic absorption spectrometry
- G01N21/35—Investigating relative effect of material at wavelengths characteristic of specific elements or molecules, e.g. atomic absorption spectrometry using infrared light
Landscapes
- Physics & Mathematics (AREA)
- Spectroscopy & Molecular Physics (AREA)
- General Physics & Mathematics (AREA)
- Health & Medical Sciences (AREA)
- Life Sciences & Earth Sciences (AREA)
- Chemical & Material Sciences (AREA)
- Analytical Chemistry (AREA)
- Biochemistry (AREA)
- General Health & Medical Sciences (AREA)
- Immunology (AREA)
- Pathology (AREA)
- Spectrometry And Color Measurement (AREA)
Abstract
The invention provides a Fourier transform spectrometer and a spectrum reconstruction method, which can utilize the energy of incident light to the maximum extent by utilizing a double blazed grating system to realize spectrum division on one dimension, so that the energy utilization rate of the incident light is higher, the light energy incident into an interference system is improved, and the signal-to-noise ratio of the whole system is ensured. And the band-pass sampling is realized by using a spatial modulation interference system in the other dimension, so that the orthogonal coupling modulation of the dispersion and the interference of the incident light field is realized in two orthogonal directions. The broadband spectrum is subjected to spectrum division and folding displacement, the spectrum resolution is improved by using low-frequency band-pass sampling, a wide spectrum range is obtained by spectrum splicing, and the technical problems of the traditional dispersion type spectrometer, the time modulation Fourier transform spectrometer and the space modulation Fourier transform spectrometer are solved in performance.
Description
Technical Field
The invention belongs to the technical field of spectral measurement, and particularly relates to a double blazed grating-based diffraction interference orthogonal coupling modulation Fourier transform spectrometer and a spectral reconstruction method.
Background
With the progress of society and the development of science and technology, the infrared spectroscopy technology has been increasingly widely applied in the fields of physics, chemistry, life, geology, medicine and the like, and plays an important role in the discovery of new materials, new energy sources and the exploration of the unknown world. In recent years, with the appearance and development of high and new technical fields such as meteorological observation, environmental monitoring, space remote sensing detection, military ground object reconnaissance and analysis and the like, higher requirements on the infrared spectrum detection technology and instruments in the aspects of volume and performance are provided due to special application environments and use conditions of the infrared spectrum detection technology and instruments.
For high and new technical fields such as meteorological observation, environmental monitoring, space detection and the like, the limitation of the use environment requires that an infrared spectrum instrument has the characteristics of microminiaturization and staticization, and the detection precision requires that the instrument has the detection performance of wide spectrum range and high resolution. With the continuous upgrading of information requirements, the traditional spectrum measurement technology has a technical bottleneck which is difficult to exceed. For conventional dispersive spectrometers, a narrow entrance slit must be used in the mid-wavelength infrared to achieve high resolution, limiting the radiant flux received by the instrument. Meanwhile, a large-area array infrared detector array is required to be adopted, and the preparation and refrigeration of the large-area array infrared detector are difficult. The Fourier transform infrared spectrometer adopts an interference light splitting mode, has a series of advantages of high luminous flux, multi-spectral channels, high wave number precision and the like, and is a preferred instrument of a high-performance infrared spectrum technology. At present, a time modulation type structure is adopted in a Fourier transform spectrometer which is conventionally applied in a laboratory, and an interferometer generates a large optical path difference through moving mirror scanning so as to obtain high spectral resolution. However, the high-precision moving mirror scanning mechanism and the precise reference light source sampling control system increase the volume and the weight of the instrument, so that the application of the instrument in high and new technical fields such as space detection, meteorological remote sensing, military reconnaissance and the like is limited.
Disclosure of Invention
The invention provides a Fourier transform spectrometer and a spectrum reconstruction method thereof, aiming at overcoming the technical problems of the traditional dispersion spectrometer, a time modulation Fourier transform spectrometer and a space modulation Fourier transform spectrometer. The broadband spectrum is subjected to spectrum segmentation and folding shift, so that the broadband spectrum can be applied to low-frequency band-pass sampling to improve spectral resolution, and a wide spectral range is obtained through spectrum splicing. In order to achieve the purpose, the invention adopts the following specific technical scheme:
a fourier transform spectrometer comprising: the device comprises a double blazed grating system and a spatial modulation interference system positioned on an emergent light path of the double blazed grating system, wherein the dispersion direction of the double blazed grating system and the modulation direction of the spatial modulation interference system are orthogonal in a transverse space, so that an incident light field is orthogonally coupled and modulated by the double blazed grating system and the spatial modulation interference system;
the double blazed grating system is used for dividing a broadband spectrum of an incident light field to form M narrow-band sliced light beams which are dispersed in color and arranged in parallel according to wavelength, each narrow-band sliced light beam corresponds to a spectrum section, and M is greater than 1;
the spatial modulation interference system is used for realizing parallel interference of each narrow-band slice beam to form an interference light field.
Preferably, the double blazed grating system comprises a first blazed grating and a second blazed grating having the same period and the same blaze angle; the first blazed grating and the second blazed grating are arranged in an antiparallel manner, so that divergent light beams with different wavelengths dispersed by the first blazed grating are reflected to the second blazed grating, reflected by the second blazed grating and then incident to the spatial modulation interference system.
Preferably, the first blazed grating is for spectrally dispersing the broadband spectrum in order of wavelength; the second blazed grating is used for collimating the dispersed divergent light beams to form M parallel-transmission narrow-band sliced light beams.
Preferably, the spatial modulation interference system comprises a plane mirror disposed on a reflection optical path of the beam splitter and a multi-stage micro-mirror disposed on a transmission optical path of the beam splitter;
the beam splitter divides M parallel-transmitted narrow-band slice beams into a first beam and a second beam according to energy; the first light beam is reflected to the plane mirror and then reflected to the beam splitter for the second time, and the second light beam is transmitted to the multi-stage micro mirror and then reflected to the beam splitter;
the reflected light of the first light beam and the reflected light of the second light beam are superposed on the beam splitter to form an interference light field.
Preferably, the multi-level micro-mirror is of a step-type structure with the same step height d, and the step direction of the multi-level micro-mirror is orthogonal to the groove line direction of the double blazed grating system, and is used for performing distributed synchronous phase modulation on the narrow-band sliced light beams with different central wavelengths.
Preferably, the step height d satisfies the following relation:
wherein k is the folding order of the spectral band corresponding to any narrow-band slice beam,
λ max for the maximum wavelength in this spectral region,
λ min the minimum wavelength in this spectral range.
Preferably, the fourier transform spectrometer further comprises a collimating mirror arranged in an incident light path of the double blazed grating system, a beam shrinking system and a planar array detector which are sequentially arranged in an emergent light path of the planar reflector;
the collimating lens is used for collimating an incident light field into parallel light;
the area array detector is used for performing photoelectric conversion on the interference light field to form a diffraction interference image.
A method of spectral reconstruction, comprising the steps of:
s1, performing diffraction interference decoupling on the diffraction interference image to obtain a low-frequency restored spectrum of the spectral band corresponding to each narrow-band slice beam in a low-frequency wave number region;
s2, carrying out low-frequency band-pass sampling on each low-frequency restored spectrum, and extracting a spectrum section unit in the original wave number region;
and S3, overlapping the extracted spectral band units on a frequency axis to obtain a spectrum of the whole wide spectral band.
Preferably, step S2 further includes the steps of:
s201, the highest wave number v of the spectral region corresponding to each narrow-band slice beam H And bandwidth B determines the folding of the spectral bandOrder k:
k＝1，2，3，…，[v H /B] (2)
wherein [ ] indicates rounding to the left;
s202, setting sampling frequency f s The interval of (a):
wherein, v L The lowest wave number of the original spectrum section where the spectrum section unit is located;
s203, folding each low-frequency restored spectrum for k times by taking 1-k times of folding frequency as an axis, frequency-shifting the low-frequency restored spectrum to a wave number region where an original spectrum section is located, and band-pass filtering the folded spectrum
The invention can obtain the following technical effects:
1. by adopting the double blazed grating system to carry out dispersion compensation, the energy of incident light can be utilized to the maximum extent, the energy utilization rate is higher, and the light energy incident into the interference system is improved.
2. Compared with the traditional dispersion spectrometer, the method avoids the narrow slit and the large array refrigeration detector which are necessary to be adopted by the dispersion spectrometer for realizing the infrared high spectral resolution, gets rid of the limitation of core devices, and has relatively high luminous flux and signal-to-noise ratio.
3. Compared with a time modulation Fourier transform spectrometer, the time modulation Fourier transform spectrometer adopts a static structure, avoids the difficulty in manufacturing and controlling caused by moving parts, and has better reliability, stability and real-time performance.
4. Compared with the traditional spatial modulation Fourier transform spectrometer, the spectral spectrum division and band-pass sampling measurement mechanism is adopted, the contradiction of mutual restriction between spectral bandwidth and spectral resolution is solved, and the spectral spectrum and the high spectral resolution can be achieved at the same time.
Drawings
FIG. 1 is an optical diagram of a Fourier spectrometer of one embodiment of the present invention;
FIG. 2 is an optical diagram of a dual blazed grating system structure and parallel dispersion according to one embodiment of the present invention;
FIG. 3 is a schematic diagram of a low frequency bandpass sampling process according to one embodiment of the invention;
FIG. 4 is an optical diagram of distributed phase modulation of a slicing beam by a multi-stage micro-mirror according to one embodiment of the present invention;
FIG. 5 is a schematic diagram of step heights of stages of a multi-stage micro mirror according to one embodiment of the invention;
FIG. 6 is a flow chart of a broad band high resolution spectral reconstruction of one embodiment of the present invention;
FIG. 7 is a flow chart of a Fourier spectrometer fabrication of an embodiment of the present invention;
FIG. 8 is a flow chart of a method of spectral reconstruction in accordance with one embodiment of the present invention.
Reference numerals are as follows:
a double blazed grating system 1, a first blazed grating 11, a second blazed grating 12,
The system comprises a spatial modulation interference system 2, a beam splitter 21, a plane mirror 22, a multi-stage micro-mirror 23, a beam shrinking system 3, an area array detector 4, a collimating mirror 5 and a light source 6.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention will be described in further detail below with reference to the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not to be construed as limiting the invention.
The invention aims to provide a Fourier transform spectrometer and a spectrum reconstruction method thereof, which adopt double blazed gratings for dispersion compensation, can utilize the energy of incident light to the maximum extent, have higher energy utilization rate, improve the light energy incident into an interference system and ensure the signal-to-noise ratio of the whole system. The following describes a fourier transform spectrometer and a spectrum reconstruction method thereof according to the present invention in detail by using specific embodiments.
Referring to the optical path diagram of the fourier spectrometer shown in fig. 1, after parallel light enters a double blazed grating system 1, the parallel light is divided into M color-dispersed narrow-band sliced light beams arranged in parallel according to wavelength, wherein M > 1; m narrow-band sliced light beams enter a spatial modulation interference system 2 positioned in an emergent light path of a double-blazed grating system 1, and are subjected to parallel interference in the spatial modulation interference system 2 to form an interference light field; the interference light field is imaged on the area array detector 4 after passing through the beam shrinking system 3, and the diffraction interference image of each spectral band corresponding to each narrow-band slice light beam is obtained through the area array detector 4.
In a preferred embodiment of the invention the dual blazed grating system 1 comprises a first blazed grating 11 and a second blazed grating 12 having the same period and the same blaze angle. The first blazed grating 11 is used for performing spectral dispersion on a broadband spectrum of an incident light field according to a wavelength sequence, and the second blazed grating 12 is used for collimating the dispersed divergent light beams to form M parallel-transmission narrow-band sliced light beams.
As shown in fig. 2, the first blazed grating 11 and the second blazed grating 12 are arranged in an antiparallel manner, so that the divergent light beams with different wavelengths dispersed by the first blazed grating 11 are reflected onto the second blazed grating 12, and are reflected by the second blazed grating 12 again and then are incident in parallel to the spatial modulation interference system 2.
In another preferred embodiment of the invention, the +1 st order of diffraction of the first blazed grating 11 is chosen as its blazed primary intensity, so that the energy of the parallel light beams from the incident light field is mostly concentrated on the +1 st order of diffraction, and the light of each wavelength of the light beams on the +1 st order of diffraction is color-dispersed due to the different wavelengths having different diffraction angles.
The dispersed light beams with various wavelengths enter the second blazed grating 12 and are reflected by the second blazed grating 12, and the-1 st diffraction order of the second blazed grating 12 is selected as the blazed primary level intensity, so that most of the energy of the light beams entering the second blazed grating 12 is concentrated on the-1 st diffraction order, and the-1 st diffraction light beams are readjusted to be transmitted in parallel due to diffraction. The light beam emerging from the second blazed grating 12 is thus a set of parallel narrow band sliced light beams arranged in wavelength order, each narrow band sliced light beam corresponding to a specific spectral band.
The spectral spacing between each narrowband sliced beam is proportional to the spacing of the first blazed grating 11 and the second blazed grating 12, and inversely proportional to the period. Therefore, by changing the spacing between the two reflective first blazed gratings 11 and the second blazed gratings 12, the spectral spacing and the spectral bandwidth between each narrowband sliced beam can be adjusted.
In another embodiment of the present invention, the first blazed grating 11 and the second blazed grating 12 are both plane reflection blazed gratings, the substrate is a metal material, or a glass material with a metal film plated on the surface, and a series of saw-toothed groove surfaces are scribed on the surface of the substrate material by using a scribing tool. The included angle between the groove carving surface and the substrate surface can be controlled by controlling the shape of the carving knife edge. By utilizing the included angle between the groove surface and the basal surface, the main intensity of the reflected light beam after the light incident on the groove surface is reflected can be concentrated to the + N-order diffraction order direction, so that most of the energy of the incident light is concentrated to the + N-order diffraction order of the first blazed grating 11. Therefore, the + N diffraction order of the first blazed grating and the-N diffraction order of the second blazed grating are selected as the blazed main intensity, and parallel transmission among each narrow-band sliced light beam can be realized.
By adopting the double blazed grating system to carry out dispersion compensation, the energy of incident light can be utilized to the maximum extent, the energy utilization rate is higher, the light energy incident into the spatial modulation interference system 2 is improved, and the signal-to-noise ratio of the whole spectrometer is ensured; meanwhile, compared with a time modulation Fourier transform spectrometer, the time modulation Fourier transform spectrometer adopts a static structure, avoids the difficulty in manufacturing and controlling caused by moving parts, and has better reliability, stability and instantaneity.
With continued reference to FIG. 1, the spatially modulated interference system 2, which is configured to achieve parallel interference of each of the narrowband sliced light beams to form an interference light field, includes a plane mirror 22 disposed in the reflected optical path of the beam splitter 21 and a multi-stage micro-mirror 23 disposed in the transmitted optical path of the beam splitter 21.
The beam splitter 21 is placed in the emergent light path of the second blazed grating 12 along the direction of 45 degrees with the optical axis, parallel narrow-band sliced light beams of M spectral bands emitted by the double blazed grating system 1 are equally divided into two light beams according to energy, the first light beam is reflected to the plane mirror 6, and the second light beam is incident to the multistage micro-mirror 23 through the beam splitter 21.
Each narrow-band slice beam with different spectral bands in the first light beam is reflected by the plane mirror 6 and then is superposed with each narrow-band slice beam in the second light beam which is modulated by the multi-stage micro-mirror 23 on the beam splitter 21 to form an interference light field.
In a preferred embodiment of the present invention, the step direction of the multi-level micro-mirror 23 is orthogonal to the groove line direction of the double blazed grating system 1, so that the incident light field can be orthogonally coupled and modulated by the double blazed grating system 1 and the spatial modulation interference system 2. Therefore, for the narrow-band slice light beam of each spectral band, the optical path difference corresponding to the interference light field is subjected to distributed modulation of different steps on the multi-stage micro-mirror 23, the diffraction interference image obtained on the area array detector 4 has two dimensions, one dimension corresponds to spectral division of parallel dispersion, the other dimension corresponds to bandpass sampling of spatial modulation, and finally, spectral information of a wide spectral band is obtained through spectral restoration and spectral splicing.
Therefore, compared with the traditional spatial modulation Fourier transform spectrometer, the method solves the contradiction of mutual restriction between the spectral bandwidth and the spectral resolution, and can simultaneously combine a wide spectral range and high spectral resolution.
As shown in the phase modulation optical path diagram of fig. 4, the multi-level micro-mirrors 23 perform distributed synchronous phase modulation on the narrowband sliced light beams with different center wavelengths by using different step heights of each micro-mirror thereon, and because the multi-level micro-mirrors 23 have a step-type structure with the same step height d, the general step height d of the multi-level micro-mirrors 23 is obtained by combining the step height diagrams of each level shown in fig. 5:
B 1 the corresponding broken line region is corresponding to the first spectral band lambda 1 Corresponding step height distribution region in the lossless sampling of narrow-band slice beam bandwidth, B 2 The corresponding broken line region is corresponding to the second spectral band lambda 2 Corresponding steps when the bandwidth of the narrow-band slice light beam is sampled without lossA height distribution area. The lambda can be obtained by the same method 3 ，λ 4 ，…，λ M And overlapping the distribution areas of all the step heights in the step height distribution areas corresponding to the narrow-band slice beams of the spectral bands, and taking the intersection of the distribution areas, namely the general step sampling height when the narrow-band slice beams of all the spectral bands are subjected to parallel sampling without spectrum aliasing. The step height d at this time satisfies the following equation:
wherein k is the folding order of the spectral band corresponding to any narrow-band slice beam,
λ max at the maximum wavelength in this spectral region,
λ min is the minimum wavelength in this spectral range.
With continued reference to fig. 1, in another preferred embodiment of the present invention, a collimating mirror 5 is further included in the incident light path of the dual blazed grating system 1, and the collimating mirror 5 may be a cylindrical collimating mirror, and is configured to collimate an incident light field with a certain divergence angle, which is emitted from the light source 6, into a parallel light beam, which is incident into the dual blazed grating system 1.
FIG. 7 shows a Fourier spectrometer fabrication process according to an embodiment of the invention, see FIG. 7:
divergent laser with the wavelength of the central wavelength of the system is used as a light source 6, the distance between the laser and the collimating mirror 5 is adjusted, and the collimation of emergent light is ensured;
placing the first blazed grating 11 in a collimation optical path, placing the second blazed grating 12 in a reflection optical path of the first blazed grating 11 along the blazed angle direction in an anti-parallel manner, and performing center alignment;
adjusting the relative position between the two blazed gratings to ensure that the transmission direction of the laser beam emitted by the second blazed grating 12 has no deflection relative to the transmission direction of the incident beam of the first blazed grating 11;
the beam splitter 21 is placed in the emergent light path of the second blazed grating 12 along the direction forming an angle of 45 degrees with the optical axis, the plane mirror 22 is placed in the reflecting light path of the beam splitter 21, the multi-stage micro-mirror 23 is placed in the transmitting light path of the beam splitter 21, the step direction of the multi-stage micro-mirror is perpendicular to the groove line direction of the double blazed grating system 1, and the center of the multi-stage micro-mirror is aligned;
adjusting the relative position between the plane mirror 22 and the multi-stage micro-mirror 23, observing whether the laser narrowband sliced light beam is vertical to the step direction of the multi-stage micro-mirror 23 and whether interference fringes are generated, if the direction is not vertical or no interference fringes are generated, continuously adjusting the relative position between the plane mirror 22 and the multi-stage micro-mirror 23 until the laser narrowband sliced light beam is vertical to the step direction of the multi-stage micro-mirror 23 and stable interference fringes are generated;
placing the beam-shrinking system 3 in the emergent light path of the plane mirror 22, and performing center alignment;
placing the area array detector 4 at the image plane position of the beam reducing system 3, and adjusting the position of the area array detector 4 relative to the beam reducing system 3 to enable the interference fringes to be imaged clearly, namely forming a diffraction interference image;
and finally, replacing the laser light source with a broadband light source.
Fig. 8 shows a flow of a method for reconstructing a spectrum acquired by a fourier spectrometer of the present invention, and with reference to fig. 8, with reference to fig. 6:
step S1, performing diffraction interference decoupling on the diffraction interference image (figure 6a) acquired by the planar array detector, dividing the diffraction interference image into interference patterns of narrow-band slice light beams corresponding to each spectral band in the horizontal dimension, matching the interference patterns with the spectral bands, and extracting an interference pattern sequence (figure 6b) of each spectral band; and matching the interferogram sequence of each spectral band with the sampling optical path difference, and performing apodization, phase correction and discrete Fourier transform operation to obtain a low-frequency restored spectrum of the spectral band corresponding to each narrow-band slice beam in a low-frequency wave number region (fig. 6 c).
In step S2, low-frequency bandpass sampling is performed on each of the obtained low-frequency restored spectra, and spectral band elements in the original wavenumber region are extracted (fig. 6 e).
In a preferred embodiment of the present invention, in conjunction with the schematic diagram of the low-pass sampling process shown in fig. 3, the step S2 includes the following three specific steps:
s201, utilizing the highest wave number v of the spectral region corresponding to each narrow-band slice beam H And bandwidth B, the folding order k of each spectral band is calculated by formula (2):
k＝1，2，3，…，[ν H /B] (2)
wherein [ ] means rounding to the left,
B＝ν H -v L ，v L the lowest wavenumber for that spectral segment;
s202, determining sampling frequency f s The interval of (c):
the sampling frequency of the interference image of the spectral band corresponding to each narrow-band slice beam is dependent on the highest wavenumber v 'of the low-frequency folded spectrum when it is sampled within the low-frequency wavenumber region' H And no longer on the highest wavenumber v of its original spectrum H I.e. the sampling frequency only needs to satisfy f s ≥v′ H I.e., so that it may be at a range of frequencies (f) below the Nyquist frequency N ＝2v H ) Is sampled at the sampling frequency of (a). In order not to cause spectrum aliasing, the sampling frequency f is set when the folding order is k s The value range of (A) is as follows:
s203, the whole broadband spectrum is divided into M narrow-band spectral bands (i.e., the spectral band corresponding to each narrow-band sliced beam) at a certain folding frequency, each spectral band is extracted (the spectral distributions of different wavelengths are different, such as triangular distribution, trapezoidal distribution, or rectangular distribution shown in fig. 3 or 6), and each extracted spectral band is folded k times along an integer multiple of the folding frequency and shifted to a low-frequency wavenumber region (fig. 6 d).
After each spectral band is folded, the high-frequency spectral information is shifted to the wavenumber region of the low frequency, and finally, the spectral bands are limited in the low-frequency region defined by the folding frequency, such as the region defined by the black thick frame shown in fig. 3.
And step S3, overlapping the extracted spectral band units on a frequency axis, so as to complete splicing of the spectral bands, and finally obtaining the whole wide-band high-resolution spectrum (fig. 6 f).
According to the spectrum reconstruction method provided by the invention, the spectrum segmentation and folding shift are carried out on the broadband spectrum, the spectrum resolution ratio can be improved by using low-frequency band-pass sampling, the wide spectrum range is obtained by spectrum splicing, the sampling limit of the traditional spatial modulation Fourier transform spectrometer under broadband measurement is overcome in performance, and the wide-spectrum-band, high-resolution and staticized measurement of the spectrum is realized.
In the description of the specification, reference to the description of "one embodiment," "some embodiments," "an example," "a specific example," or "some examples" or the like means that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the invention. In this specification, the schematic representations of the terms used above are not necessarily intended to refer to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples. Furthermore, various embodiments or examples and features of different embodiments or examples described in this specification can be combined and combined by one skilled in the art without contradiction.
Although embodiments of the present invention have been shown and described above, it will be understood that the above embodiments are exemplary and not to be construed as limiting the present invention, and that changes, modifications, substitutions and alterations can be made to the above embodiments by those of ordinary skill in the art within the scope of the present invention.
The above embodiments of the present invention should not be construed as limiting the scope of the present invention. Any other corresponding changes and modifications made according to the technical idea of the present invention should be included in the protection scope of the claims of the present invention.
Claims (6)
1. A fourier transform spectrometer, comprising: the device comprises a double blazed grating system and a spatial modulation interference system positioned on an emergent light path of the double blazed grating system, wherein the dispersion direction of the double blazed grating system and the modulation direction of the spatial modulation interference system are orthogonal in a transverse space, so that an incident light field is subjected to orthogonal coupling modulation by the double blazed grating system and the spatial modulation interference system;
the double blazed grating system is used for dividing a broadband spectrum of the incident light field to form M narrow-band sliced light beams which are dispersed in color and arranged in parallel according to wavelength, each narrow-band sliced light beam corresponds to a spectrum section, and M is greater than 1;
the spatial modulation interference system is used for realizing parallel interference on each narrow-band slice light beam to form an interference light field; the spatial modulation interference system comprises a plane mirror arranged on a reflection light path of the beam splitter and a multi-stage micro mirror arranged on a transmission light path of the beam splitter; the beam splitter divides the M parallel-transmitted narrow-band slicing light beams into a first light beam and a second light beam according to energy; the first light beam is reflected to the plane mirror and then reflected to the beam splitter for the second time, and the second light beam is transmitted to the multi-stage micro mirror and then reflected to the beam splitter; the reflected light of the first light beam and the reflected light of the second light beam are superposed on the beam splitter to form the interference light field;
the multistage micro reflector is of a step-shaped structure with the same step height d, the step direction of the multistage micro reflector is orthogonal to the groove line direction of the double blazed grating system, and the multistage micro reflector is used for carrying out distributed synchronous phase modulation on the narrow-band sliced light beams with different central wavelengths;
the step height d satisfies the following relation:
wherein k is a spectrum corresponding to any one of the narrowband sliced beamsFolding order of segments, λ max Is the maximum wavelength, λ, of the spectral range min Is the minimum wavelength in this spectral range.
2. The fourier transform spectrometer of claim 1, wherein the dual blazed grating system comprises a first blazed grating and a second blazed grating having the same period and the same blaze angle; the first blazed grating and the second blazed grating are arranged in an antiparallel manner, so that divergent light beams with different wavelengths dispersed by the first blazed grating are reflected to the second blazed grating, reflected by the second blazed grating and then incident to the spatial modulation interference system.
3. The fourier transform spectrometer of claim 2, wherein the first blaze grating is configured to spectrally disperse the broadband spectrum in order of wavelength; the second blazed grating is used for collimating the dispersed divergent light beams to form M parallel-transmitted narrow-band sliced light beams.
4. The fourier transform spectrometer of claim 1, further comprising a collimating mirror disposed in an incident optical path of the dual blazed grating system, a beam reduction system disposed in an exit optical path of the plane mirror in sequence, and an area array detector;
the collimating lens is used for collimating the incident light field into parallel light;
the area array detector is used for performing photoelectric conversion on the interference light field to form a diffraction interference image.
5. A spectral reconstruction method applied to an image obtained using a fourier transform spectrometer as claimed in any one of claims 1 to 4, comprising the steps of:
s1, performing diffraction interference decoupling on the diffraction interference image to obtain a low-frequency restored spectrum of the spectral band corresponding to each narrow-band slice beam in a low-frequency wave number region;
s2, carrying out low-frequency band-pass sampling on each low-frequency restored spectrum, and extracting a spectrum section unit in an original wave number region;
and S3, overlapping the extracted spectral band units on a frequency axis to obtain a spectrum of the whole wide spectral band.
6. The spectral reconstruction method according to claim 5, wherein the step S2 further comprises the steps of:
s201, the highest wave number v of the spectral region corresponding to each narrow-band slice beam H And bandwidth B determines the folding order k of the spectral band:
k＝1，2，3，…，[ν H /B] (2)
wherein [ ] represents rounding to the left;
s202, setting sampling frequency f s The interval of (c):
wherein, v L The lowest wave number of the original spectrum section where the spectrum section unit is located;
s203, folding each low-frequency restored spectrum for k times by taking the folding frequency of 1-k times as an axis, shifting the spectrum to the wave number region where the original spectrum section is located, and performing band-pass filtering on the folded spectrum.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202110603234.5A CN113280915B (en) | 2021-05-31 | 2021-05-31 | Fourier transform spectrometer and spectrum reconstruction method |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202110603234.5A CN113280915B (en) | 2021-05-31 | 2021-05-31 | Fourier transform spectrometer and spectrum reconstruction method |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN113280915A CN113280915A (en) | 2021-08-20 |
| CN113280915B true CN113280915B (en) | 2022-07-26 |
Family
ID=77282756
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202110603234.5A Active CN113280915B (en) | 2021-05-31 | 2021-05-31 | Fourier transform spectrometer and spectrum reconstruction method |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN113280915B (en) |
Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101251484A (en) * | 2008-04-10 | 2008-08-27 | 中国科学院长春光学精密机械与物理研究所 | Miniature fourier transform spectrometer based on modulation |
| CN103868596A (en) * | 2014-02-21 | 2014-06-18 | 中国科学院光电研究院 | Large-aperture space heterodyne interference spectral imaging method and spectrometer |
| CN103913227A (en) * | 2014-03-10 | 2014-07-09 | 中国科学院长春光学精密机械与物理研究所 | Infrared imaging spectrometer based on light beam splitter and manufacturing method |
| CN106352985A (en) * | 2016-09-30 | 2017-01-25 | 中国科学院光电技术研究所 | Asymmetric spatial heterodyne spectrometer structure |
| CN112129409A (en) * | 2020-08-19 | 2020-12-25 | 中国科学院西安光学精密机械研究所 | Interference spectrum system based on band-pass sampling technology and target spectrum information acquisition method |
-
2021
- 2021-05-31 CN CN202110603234.5A patent/CN113280915B/en active Active
Patent Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101251484A (en) * | 2008-04-10 | 2008-08-27 | 中国科学院长春光学精密机械与物理研究所 | Miniature fourier transform spectrometer based on modulation |
| CN103868596A (en) * | 2014-02-21 | 2014-06-18 | 中国科学院光电研究院 | Large-aperture space heterodyne interference spectral imaging method and spectrometer |
| CN103913227A (en) * | 2014-03-10 | 2014-07-09 | 中国科学院长春光学精密机械与物理研究所 | Infrared imaging spectrometer based on light beam splitter and manufacturing method |
| CN106352985A (en) * | 2016-09-30 | 2017-01-25 | 中国科学院光电技术研究所 | Asymmetric spatial heterodyne spectrometer structure |
| CN112129409A (en) * | 2020-08-19 | 2020-12-25 | 中国科学院西安光学精密机械研究所 | Interference spectrum system based on band-pass sampling technology and target spectrum information acquisition method |
Also Published As
| Publication number | Publication date |
|---|---|
| CN113280915A (en) | 2021-08-20 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CN103913227B (en) | Based on Infrared Imaging Spectrometer and the method for making of light-duty beam splitter | |
| CN102052968B (en) | Wide-spectrum spatial heterodyne spectrometer | |
| CN110501289B (en) | Spectrum broadening method and device based on digital micromirror array (DMD) | |
| US11307096B2 (en) | Spectral resolution enhancement device | |
| CN201897503U (en) | Wide-spectral-coverage spatial heterodyne spectrometer | |
| CN102944310B (en) | Spectral resolution adjustable interference imaging spectrometer | |
| US11237056B2 (en) | Monolithic assembly of reflective spatial heterodyne spectrometer | |
| CN205808912U (en) | Compact high-resolution wide visual field spectrum imaging system | |
| Ben-Ami et al. | High-resolution spectroscopy using Fabry–Perot interferometer arrays: an application to searches for O2 in exoplanetary atmospheres | |
| EP4242708A2 (en) | Polarization spectral filter, polarization spectral filter array, and polarization spectral sensor | |
| CN208270077U (en) | The high-throughput high-resolution relevant dispersion spectrum imaging device of wide spectrum | |
| CN110501074B (en) | High-flux wide-spectrum high-resolution coherent dispersion spectrum imaging method and device | |
| Kentischer et al. | The visible tunable filtergraph for the ATST | |
| CN113280915B (en) | Fourier transform spectrometer and spectrum reconstruction method | |
| CN108387317A (en) | A kind of prism-type space heterodyne spectrograph | |
| CN108362381B (en) | Wide-field large-aperture spatial heterodyne interference imaging spectrometer | |
| CN106352985A (en) | Asymmetric spatial heterodyne spectrometer structure | |
| CN113624339B (en) | Homodromous dispersive spectrum analyzer and method based on DMD and echelle grating | |
| Kawata | Instrumentation for near-infrared spectroscopy | |
| CN112504457B (en) | Spatial heterodyne spectrometer applied to DWDM system | |
| US11639873B2 (en) | High resolution multi-pass optical spectrum analyzer | |
| CN113280916B (en) | Fourier transform spectrometer | |
| CN108507679A (en) | A kind of wide spectrum high-resolution spectra interferometric method and device | |
| CN208887786U (en) | A kind of high resolution spectrometer | |
| CN113447125B (en) | Multi-resolution mode interference spectrum system |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination | ||
| GR01 | Patent grant | ||
| GR01 | Patent grant |