Interferometric spectral imaging system and method based on a light comb light source

Abstract

The present disclosure provides an interferometric spectral imaging system and method based on a light comb light source, wherein the imaging system comprises: a light comb light source unit for providing a first light comb light source; a gas absorption unit for loading a to-be-measured gas, wherein the first light comb light source transmits through the to-be-measured gas to obtain a second light comb light source; a light source processing unit for collimating and filtering the second light comb light source to obtain incident light; an interference unit for causing the incident light to interfere to form interference fringes; an imaging unit for imaging the interference fringes to obtain a fringe pattern; and an analysis unit for analyzing the fringe pattern to obtain an analysis result, wherein the analysis result comprises a component of the to-be-measured gas.

Description

TECHNICAL FIELD

[0001] The present disclosure relates to the technical field of optical precision measurement, and in particular, to an interference spectrum imaging system and method based on a light comb light source. BACKGROUND

[0002] At present, the development of high-precision spectrum measurement based on optical frequency combs is relatively rapid. In the time domain, the optical frequency comb is a super-short femtosecond optical pulse, and in the frequency domain, it is a comb spectrum composed of equally spaced optical frequencies, and each frequency component has a stable phase relationship. The optical frequency comb has the advantages of high bandwidth, short-time stability and good long-time stability.

[0003] The existing spectrum measurement methods are divided into two categories. One category is to replace the original ordinary light source with a femtosecond light source to improve the measurement accuracy and sensitivity of the original spectrum measurement method by using the characteristics of the optical frequency comb. The other category is to use two femtosecond optical frequency combs with a small repetition frequency difference as a coherent light source, i.e., a dual-comb method, to realize fast asynchronous optical sampling and multi-heterodyne interference detection. The spectrum data to be measured is obtained by Fourier transform of the interference signal and frequency mapping of the spectrum signal. In the frequency domain, it is equivalent to the multi-frequency down-conversion between the two optical combs. Thus, the high-frequency optical signal can be down-converted to the low-frequency microwave band, and finally the large-bandwidth measured signal information can be obtained with a relatively low measurement bandwidth.

[0004] Among them, the dual-comb method can realize high-resolution wideband detection without the need for dispersion elements and array detectors. Compared with the traditional mechanical Michelson interferometer, it breaks through the limitations of mechanical scanning in scanning speed and stability. With the advancement of microcavity manufacturing technology, microcavities such as microdisks, microloops or microspheres with high quality factors are made, which makes it possible to realize chip integration of optical frequency combs. Chip-integrated microcavity optical combs have the advantages of high repetition frequency and the potential to realize portable detection devices compared with traditional optical combs. Since its inception, this miniaturized light source has been rapidly and widely applied in precision spectrum measurement research. The dual-comb system composed of microcavities can realize nanosecond-level spectrum testing speed, making it possible to miniaturize the dual-comb sensing application.

[0005] However, at the present stage, the construction of a dual-comb system using a chip-integrated platform requires locking the optical frequency comb modes generated in the two microcavities, and a feedback control system is needed to ensure the high stability of the spectrum components of the two optical frequency combs to realize the mutual coherence between the two optical frequency combs. In addition, a frequency stabilization system is also needed for the construction of a dual-comb system using a chip-integrated platform, which greatly increases the complexity of the system and hinders the development of this technology to daily applications and low-cost production. SUMMARY

[0006] Therefore, the present disclosure provides an interference spectrum imaging system and method based on a light comb light source to at least partially solve the above technical problems.

[0007] To solve the above technical problems, the technical solutions provided by the present disclosure are as follows:

[0008] As an aspect of the present disclosure, an interference spectrum imaging system based on an optical comb light source is provided, comprising:

[0009] An optical comb light source unit is configured to provide a first optical comb light source;

[0010] A gas absorption unit is configured to load a to-be-measured gas, wherein the first optical comb light source transmits through the to-be-measured gas to obtain a second optical comb light source;

[0011] A light source processing unit is configured to perform collimation processing and filtering processing on the second optical comb light source to obtain incident light;

[0012] An interference unit is configured to cause the incident light to interfere to form interference fringes;

[0013] An imaging unit is configured to perform imaging processing on the interference fringes to obtain a fringe pattern;

[0014] An analysis unit is configured to perform analysis processing on the fringe pattern to obtain an analysis result, wherein the analysis result includes a component of the to-be-measured gas.

[0015] According to an embodiment of the present disclosure, the optical comb light source unit comprises a chip-integrated optical frequency comb.

[0016] According to an embodiment of the present disclosure, the light source processing unit comprises a collimation module and a filtering module.

[0017] According to an embodiment of the present disclosure, the collimation module is configured to perform collimation processing on the second optical comb light source and input the collimated second optical comb light source to the filtering module;

[0018] The filtering module is configured to filter out the center pump frequency of the collimated second optical comb light source to form the incident light entering the interference unit.

[0019] According to an embodiment of the present disclosure, the filtering module can also filter out the comb teeth on both sides of the center wavelength of the second optical comb light source based on a preset spectral range.

[0020] According to an embodiment of the present disclosure, the collimation module comprises a collimation mirror.

[0021] The filtering module comprises a filter.

[0022] According to an embodiment of the present disclosure, the interference unit comprises a Fizeau interferometer.

[0023] The imaging unit comprises a detector.

[0024] According to an embodiment of the present disclosure, the detector is configured to detect the light signal of the interference fringes to obtain an interference pattern.

[0025] According to an embodiment of the present disclosure, the Fizeau interferometer comprises two flat plates plated with high reflectivity thin film surfaces;

[0026] The detector comprises a photonic detector array.

[0027] As another aspect of the present disclosure, an interference spectrum imaging method based on a light comb light source is disclosed, comprising:

[0028] A first light comb light source is provided by using a light comb light source unit;

[0029] The first light comb light source is transmitted through a gas absorption unit loaded with a to-be-measured gas to obtain a second light comb light source;

[0030] The second light comb light source is collimated and filtered by using a light source processing unit to obtain incident light;

[0031] The incident light is interfered to form interference fringes by using an interference unit;

[0032] The interference fringes are imaged by using an imaging unit to obtain a fringe pattern;

[0033] The fringe pattern is analyzed by using an analysis unit to obtain an analysis result, wherein the analysis result includes the composition of the to-be-measured gas.

[0034] Based on the above technical solutions, the interference spectrum imaging system and method based on the light comb light source provided by the present disclosure have at least one of the following beneficial effects:

[0035] (1) In an embodiment of the present disclosure, a light comb light source is provided by setting a light comb light source unit. The light beam of the light comb light source generates interference fringes with equal thickness through an interference unit, has high resolution, and is received by an imaging unit. The interference fringes enter the corresponding channels of the detector in the imaging unit to detect the fringe intensity distribution and fringe movement, and form a fringe pattern.

[0036] (2) In an embodiment of the present disclosure, the interference unit provided by the present disclosure can make the entire system fully solid-state, and signal processing and high-speed detection imaging can be realized without applying frequency scanning technology. The defects of high system complexity, low scanning frequency and low spectral resolution existing in the existing high-precision gas spectrum detection technology are overcome.

[0037] (3) In an embodiment of the present disclosure, the combination of the light comb light source and the interference unit has high sensitivity and high spectral resolution, and can be applied to fields such as atmospheric remote sensing, combustion diagnosis, industrial gas emission and greenhouse gas detection. The precision and speed of gas spectrum detection are improved, and a new direction for the practical application of the light comb spectrum system is provided. BRIEF DESCRIPTION OF DRAWINGS

[0038] Figure 1 A schematic diagram of an interferometric spectral imaging system based on a light comb light source in an embodiment of the present disclosure;

[0039] Figure 2 A schematic diagram of a principle of processing spectrum by an interference unit in an embodiment of the present disclosure;

[0040] Figure 3 A fringe pattern intensity distribution map obtained in an embodiment of the present disclosure;

[0041] Figure 4 A fringe pattern obtained in embodiment 1 of the present disclosure.

[0042] The following description of the figures refers to the accompanying drawings, in which:

[0043] 1 - light comb light source unit;

[0044] 2 - gas absorption unit;

[0045] 3 - light source processing unit;

[0046] 31 - collimation module;

[0047] 32 - filtering module;

[0048] 4 - interference unit;

[0049] 5 - imaging unit;

[0050] 6 - analysis unit. DETAILED DESCRIPTION

[0051] In order to make the objects, technical solutions and advantages of the present disclosure clearer, the following will further describe the present disclosure in conjunction with specific embodiments and with reference to the drawings.

[0052] Hereinafter, embodiments of the present disclosure will be described with reference to the accompanying drawings. However, it should be understood that these descriptions are merely exemplary and are not intended to limit the scope of the present disclosure. In the following detailed description, numerous specific details are set forth in order to provide a thorough understanding of the embodiments of the present disclosure. However, it will be apparent to one of ordinary skill in the art that one or more embodiments can be practiced without these specific details. In addition, in the following description, descriptions of well-known structures and techniques have been omitted to avoid unnecessarily obscuring the concept of the present disclosure.

[0053] The terms used herein are merely used to describe specific embodiments and are not intended to limit the present disclosure. The terms "include", "comprise" and the like used herein indicate the presence of the features, steps, operations and / or components, but do not exclude the presence or addition of one or more other features, steps, operations or components.

[0054] All terms used herein (including technical and scientific terms) have meanings that are commonly understood by one of ordinary skill in the art unless otherwise defined. It should be noted that the use of any term in this specification should not be interpreted as an idealized or overly formal sense unless expressly so defined.

[0055] In the case of using expressions such as "at least one of A, B, and C", it will generally be understood that such expression is used to include any of A, B, or C, any combination of A, B, and C, and / or the entire set of A, B, and C (i.e., A, B, and / or C) unless otherwise defined or unless it is clear from the context of the description that it is used only to designate a specific set of A, B, and C. In the case of using an expression such as "at least one of A, B, or C", it will generally be understood that such expression is used to include any of A, B, or C, any combination of A, B, and C, and / or the entire set of A, B, and C (i.e., A, B, and / or C) unless otherwise defined or unless it is clear from the context of the description that it is used only to designate a specific set of A, B, and C.

[0056] At present, spectral imaging technology can be divided into dispersion type and interference type according to its dispersion principle, among which, dispersion imaging disperses incident polychromatic light into discrete quasi-monochromatic spectrum lines through typical dispersion devices such as prisms and gratings, and the fine and sharp stripes formed by different wavelengths appear at different positions, which performs narrow-band selection on wide spectrum; while interference imaging spectral technology uses the mapping relationship between the interference stripes formed by incident light and its spectral components, and through collecting the intensity of interference patterns and analyzing it, the spectral diagram of the detected target is inversed, and then the spectral information of the target is obtained. In order to realize high-sensitivity detection of regional gas spectrum, effective real-time monitoring means is needed to characterize and study the gas spectrum.

[0057] In the process of implementing the present disclosure, it is found that there is still great application potential in using a single microcavity optical frequency comb as a spectrum detection tool. With the continuous upgrading of light sources, the problem to be solved is how to more effectively characterize the detected spectrum signal. The local mechanical scanning grating spectrometer in the prior art can be suitable for wide spectrum measurement, but the high process requirement leads to a limit of the spectral resolution and possible aliasing interference between multiple diffraction lines. The traditional dispersive spectral imager with a slit has a slit that limits the incident light. The width of the slit affects the resolution and light flux of the spectrometer. The measured spectral unit can only pass through the slit one by one, that is, only a specific spectral unit can be measured at each moment. Due to the limitation of mechanical scanning rate, the frame rate is generally in the order of Hz, and only static results can be obtained. In addition, in the interference spectrometer, the incident signal light can pass through the interferometer at the same time and form an interference pattern on the detector to realize simultaneous measurement of multiple components. Most of the existing multi-beam interference systems are based on Fabry-Perot interferometers. This type of spectrometer can achieve high spectral resolution. When combined with a CCD array, although the rate can be improved to the order of kHz, factors such as the mismatch between the ring-shaped interference fringes generated and the linear pixel detector mainly used will lead to resolution degradation.

[0058] In the process of implementing the present disclosure, it is found that through stable spectrum measurement, the information of the measured gas spectrum can be intuitively displayed, greatly promoting the development of high-resolution spectrum detection technology. However, the Hz-level measurement rate means that some important dynamic processes may be missed, so it cannot be applied to real-time spectrum characterization of microcavity optical frequency combs. Therefore, there is a need to connect an interferometer with a high-resolution linear fringe to realize the real-time spectrum characterization of microcavity optical frequency combs.

[0059] Therefore, the present disclosure provides an interference spectral imaging system and method based on an optical comb light source. Specifically, as one aspect of the present disclosure, an interference spectral imaging system based on an optical comb light source is provided, which comprises:

[0060] An optical comb light source unit is configured to provide a first optical comb light source.

[0061] A gas absorption unit is configured to load a to-be-measured gas. The first optical comb light source passes through the to-be-measured gas to obtain a second optical comb light source.

[0062] A light source processing unit is configured to perform collimation processing and filtering processing on the second optical comb light source to obtain incident light.

[0063] An interference unit is configured to cause the incident light to interfere to form an interference fringe.

[0064] An imaging unit is configured to perform imaging processing on the interference fringe to obtain a fringe pattern.

[0065] The analysis unit is configured to analyze the fringe pattern to obtain an analysis result, wherein the analysis result comprises a component of the to-be-detected gas.

[0066] According to the embodiment of the present disclosure, the optical comb light source unit can provide an optical comb light source, the optical microcavity of the optical comb light source unit has super-high quality factor and extremely strong field enhancement effect, the working threshold of the optical comb can be as low as milliwatt level, and each comb tooth has very narrow linewidth, which is completely suitable for spectral precision measurement application. At the same time, the microcavity optical comb of the optical comb light source unit has high repetition frequency, which improves the spectral measurement speed.

[0067] According to the embodiment of the present disclosure, the interference unit can effectively characterize the detected spectral signal, the formed interference fringe has high resolution, and the uniform incident of the quasi-monochromatic light source forms localized equal-thickness fringes on or near the wedge surface after reflection and transmission in the interferometer. The signal processing and high-speed detection imaging can be realized without applying frequency scanning technology. The defects of high system complexity, low scanning frequency and low spectral resolution existing in the existing high-precision gas spectral detection technology are overcome.

[0068] According to the embodiment of the present disclosure, the optical comb light source unit is provided by setting the optical comb light source, the optical comb light source beam passes through the interference unit to generate equal-thickness interference fringes, which has high resolution, and the imaging unit receives the interference fringes. The interference fringes enter the corresponding channel of the detector in the imaging unit, and the fringe intensity distribution and fringe movement can be detected, forming a fringe pattern with high stability and high resolution.

[0069] According to the embodiment of the present disclosure, the optical comb light source unit includes a chip-integrated optical frequency comb, which has the characteristics of high repetition frequency and wide spectral coverage, and can realize ultrafast measurement, wide spectral measurement and high-precision measurement. The traditional optical frequency comb is realized based on solid or fiber mode-locked laser. Compared with the disadvantages of volume, weight, power consumption and cost of traditional optical frequency comb, the chip-integrated optical frequency comb provided by the present disclosure can fully exert the application potential of optical frequency comb in precision measurement.

[0070] According to the embodiment of the present disclosure, the gas absorption unit can also be replaced by other units that can transmit light beams, which is used to contain other to-be-detected substances that can absorb part of the first optical comb light source and allow the remaining light beams to pass through.

[0071] According to the embodiment of the present disclosure, the light source processing unit includes a collimation module and a filtering module, wherein the collimation module is configured to collimate the second optical comb light source, and input the collimated second optical comb light source to the filtering module; and the filtering module is configured to filter out the center pumping frequency of the collimated second optical comb light source to form incident light into the interference unit.

[0072] Figure 1 As shown in FIG. 1, the interference spectrum imaging system based on the optical comb light source provided by the present disclosure comprises: an optical comb light source unit 1, a gas absorption unit 2, a light source processing unit 3, an interference unit 4, an imaging unit 5, and an analysis unit 6. The light source processing unit 3 comprises a collimating module 31 and a filtering module 32. Figure 1

[0073] According to the embodiment of the present disclosure, the filtering module can further filter out the teeth on both sides of the center wavelength of the second optical comb light source based on the range of the preset spectrum. By filtering out the background noise of the spectrum through the filtering module, the influence of the noise on the system is reduced, the signal-to-noise ratio of the system is improved, and the light of the pump light source is filtered out at the same time, so that the output light signal is the same frequency as the original input light signal. For example, the spectrum outside 300-500 nm can be filtered out, the spectrum outside 500-700 nm can be filtered out, etc. The range of the teeth on both sides can be selected according to the experimental situation.

[0074] According to the embodiment of the present disclosure, the collimating module comprises a collimating mirror, and the filtering module comprises a filter.

[0075] According to the embodiment of the present disclosure, the second optical comb light source is collimated into parallel light after passing through the collimating mirror. The collimating mirror can be a convex lens, and the parameters of the convex lens can be selected according to the actual situation.

[0076] According to the embodiment of the present disclosure, the interference unit comprises a Fizeau interferometer. The Fizeau interferometer type spectrometer has the advantages of high wave number precision, low stray light influence, high resolution power, wide spectral measurement range, and compact structure. The Fizeau interferometer comprises two flat plates with high reflectivity film surfaces, which can divide the incident light into first and second exit light, thereby generating the interference fringes.

[0077] According to the embodiment of the present disclosure, the imaging unit comprises a detector, which is used for detecting the light signal of the interference fringes to obtain the interference pattern. The detector can comprise a photon detector array (CCD detector array).

[0078] According to the embodiment of the present disclosure, Figure 2 As shown in FIG. 2, a multi-beam Fizeau interferometer is composed of two flat plates with high reflectivity film surfaces, which are slightly inclined to each other at a small angle α. The exit surface is placed in the xOy plane. The reflection coefficients of the two reflecting surfaces are r and r', and the transmission coefficients are t and t'. The optical path difference between the light beam directly reaching the P point and the nth exit light beam is: Figure 2

[0079] Δ n = PN​​n -PN0

[0080] = z [cos (θ + 2nα) - cos θ] + y [sin (θ + 2nα) - sin θ] (1)

[0081] where W n is the wavefront of the nth outgoing light passing through point O, N n is the intersection of W n and the nth outgoing light, θ is the angle between the incident light and the interferometer panel, and the coordinates of point P are (y, z).

[0082] The phase difference between the light beam directly reaching point P and the nth outgoing light is:

[0083]

[0084] where λ is the wavelength of the incident light; φ is the phase loss upon reflection, generally φ = π, and the phase loss upon transmission is not considered because the mirror surface is very thin.

[0085] Considering that the wedge angle α is a small angle, the optical path difference Δ n can be expanded to retain the second-order term:

[0086]

[0087] If the amplitude of the incident wavefront is E0, the combined amplitude of the transmitted light at point P is:

[0088]

[0089] where R = rr', T = tt', and i is the imaginary unit If the absorption loss A of the reflective film is considered, then T = 1 - R - A.

[0090] Because the intensity of the nth outgoing light beam decreases rapidly as n increases, the influence of the high-order terms is small, so the equation (3) can be retained to the linear term of n and defined as The interference maximum condition can be treated as 2L eff cos θ = mλ, which is consistent with the Fabry-Perot interferometer (FP interferometer), so each small section of the Fizeau interferometer can be regarded as a Fabry-Perot etalon corresponding to the cavity length. The interference fringe characteristics of the Fizeau interferometer are similar to those of the FP interferometer. When a uniform monochromatic light source is incident, reflection and transmission occur in the multi-beam Fizeau interferometer, and localized equal-thickness fringes are formed on or near the wedge surface. With the change of the relative position of the incident light beam and the wedge, the same interference fringes appear in different detection planes. Each fringe is slightly different depending on the average cavity length at the incident point and the wavelength of the incident light.

[0091] If the incident light source is not strictly monochromatic, but there are two components with a wavelength difference Δλ, the independently generated interference fringe spacing of each component will have a small difference, which gradually increases with the increase of the fringe order m, and the spacing of the adjacent order fringes is Thus, the positions of the mth order fringes of wavelengths λ1 and λ2 on the receiving screen are respectively:

[0092] y1=md1=mλ1 / 2α (5)

[0093] y2=md2=mλ2 / 2α (6)

[0094] The corresponding fringe separation is:

[0095] Δy m =y2-y1=mΔλ / 2α (7)

[0096] Although the distances of different order interference fringes of different wavelengths relative to the end points of the observation area are different, the separation of adjacent order fringes is only proportional to the wavelength difference (and independent of the interference order), which can be used to identify the wavelengths corresponding to the fringes at different positions. The relative positions of the interference fringes formed by different wavelengths of monochromatic light on the detector are different, a certain wavelength of the fringes can be calibrated by using a reference light, and the separation of other wavelengths from the fringe can be measured, and the relationship between the separation and the wavelength difference is used for spectral resolution, so that the inversion of the spectrum can be realized by detecting the separation of the fringe pattern.

[0097] As another aspect of the present disclosure, an interference spectrum imaging method based on an optical comb light source is disclosed, comprising steps S101-S106:

[0098] In step S101, a first optical comb light source is provided by using an optical comb light source unit;

[0099] In step S102, the first optical comb light source is made to pass through a gas absorption unit loaded with a to-be-measured gas to obtain a second optical comb light source;

[0100] In step S103, the second optical comb light source is collimated and filtered by using a light source processing unit to obtain incident light;

[0101] In step S104, the incident light is made to interfere to form interference fringes by using an interference unit;

[0102] In step S105, the interference fringes are imaged by using an imaging unit to obtain a fringe pattern;

[0103] In step S106, the fringe pattern is analyzed by using an analysis unit to obtain an analysis result, wherein the analysis result includes the composition of the to-be-measured gas.

[0104] According to embodiments of this disclosure, the following is combined with Figure 1 A brief explanation of the interferometric spectral imaging method based on a light comb source is provided. A first light comb source with a known repetition frequency and bias frequency is provided by light comb source unit 1. A gas absorption unit 2 is used to load the gas to be measured. After passing through the gas absorption unit 2, the light intensity of the first light comb source is weakened due to absorption by gas molecules, thus forming a second light comb source. The second light comb source then enters the collimation module 31 in the light source processing unit 3. The second light comb source is collimated to form parallel light. The collimated beam then enters the filtering module 32 for filtering, which filters out the central pump frequency and the comb teeth on both sides of the second light comb source. After collimation and filtering, the second light comb source becomes the incident light that can enter the interferometer unit 4. Based on the wave nature of light and the principle of constructive interference, interference unit 4 is used to cause interference of incident light to form interference fringes. The optical signal of the interference fringes is detected by imaging unit 4 to obtain the interference pattern. The interference pattern is analyzed and processed by analysis unit 5. By analyzing the interference pattern, the spectrum of the light beam before passing through the gas medium, and the intensity change of the light beam, the composition of the gas to be measured in gas absorption unit 2 and the concentration information of each component are analyzed.

[0105] Figure 3 The fringe pattern intensity distribution map obtained in this embodiment is as follows: when the incident light enters the Fizeau interferometer of the interferometer unit at an angle θ, the intensity distribution map is obtained in the CCD detector array of the imaging unit. Figure 3 The intensity distribution of the stripe pattern is shown. For example... Figure 3 The diagram shows three observation zones of different orders. The endpoints are marked by fringes with larger peak values ​​on either side, indicating the reference wavelength λ. The interval between the endpoints of each zone is λ / 2α. The two middle fringes represent the positional distribution of the components in the light under test whose wavelengths differ from λ by Δλ and Δλ′, respectively, relative to the endpoints. The difference in fringe separation at the same wavelength within adjacent observation zones, i.e., the distance from the m±1 order fringe to the m order fringe (dashed line), is Δλ / 2α, where Δλ is the wavelength difference from the wavelength corresponding to the fringe at the endpoint. By observing the differences in fringe separation at various positions, the wavelength differences corresponding to each fringe in the m-th order observation zone can be obtained, allowing for the analysis and calculation of the discrete components of the incident signal's light spectrum.

[0106] To make the objectives, technical solutions, and advantages of this disclosure clearer, the technical solutions and principles of this disclosure are further illustrated below with reference to specific embodiments and accompanying drawings. It should be noted that the specific embodiments described below are merely illustrative examples, and the scope of protection of this disclosure is not limited thereto.

[0107] The test materials and reagents used in the following examples, and the like, can be obtained from commercial channels if not otherwise specified. The specific techniques or conditions not noted in the examples are conventional methods, which can be carried out according to the techniques or conditions described in the literature in the art or according to the product instructions. The examples of the present disclosure are as follows:

[0108] A first optical comb light source with equal frequency intervals and a size of about 20GHz is provided by using a continuous wave laser with a wavelength of 1550nm to pump a micro-ring cavity to obtain a chip-integrated optical frequency comb. The first optical comb light source passes through a gas absorption cell at a vacuum light speed of 299792458m / s to obtain a second optical comb light source, which is the optical frequency comb signal to be measured. After collimation processing by a convex lens, the second optical comb light source enters a filter in parallel and is processed by the filter to retain thirteen comb teeth as incident light, which is normally incident to a Fizeau interferometer at an angle of 1.95mrad. The distance between the two mirrors at the light beam incident point is 1mm on average, and the reflection coefficient is adjusted to 0.992. The angle formed by the two plates in the Fizeau interferometer is set to 4.1μrad. The incident light forms interference fringes, and the wavelength with higher power is taken as a reference, as shown in FIG. 1, and the interference fringes are imaged on a CCD detector array near the rear surface of the Fizeau interferometer to obtain a clear fringe pattern. Figure 4

[0109] The parameters of the light source and the imaging system in the example 1 of the present disclosure are as follows:

[0110]

[0111] Figure 4 The fringe pattern obtained in the example 1 of the present disclosure is shown in FIG. 2, which can effectively distinguish a wavelength difference of 0.16nm, and can achieve the wavelength resolution of a high-performance grating spectrometer to realize high-resolution and fast spectral acquisition. Figure 4

[0112] wherein, Figure 4 Adjusting the upper and lower two figures to differ from the middle observation order by 20 can make the smallest fringe separation greater than the pixel resolution of the CCD, otherwise the separation cannot be measured. As can be seen from the fringe pattern in FIG. 3, the fringe separation at the same wavelength in different observation orders is linearly increased, and the spectrum of the signal can be further inverted by reading the readings of each detector channel. Figure 4

[0113] ​​​Based on the above embodiments, it can be seen that the interference spectral imaging system and method based on the optical comb light source provided by the present disclosure can avoid the shortcomings that the resolution of the current microcavity optical frequency comb system is reduced due to the limitation of the mechanical scanning rate or the degradation of the stripes at the signal receiving end, so that high-resolution fast spectral detection cannot be realized by using the system. The present disclosure combines the light beam source with interference imaging, uses chip integrated optical frequency comb to play the advantages of chip optical comb miniaturization and high spectral resolution, and combines with Fizeau interferometer to realize high-speed detection imaging. The high-sensitivity spectral detection technology can be developed, which is a potential ideal tool for multi-component, large-range and continuous real-time monitoring. The spectral imaging system and method taking spectral method as the main means are beneficial to establish regional gas monitoring system, carry out gas monitoring and open atmosphere gas monitoring, and can be widely applied to environmental protection, climate, industrial safety and other fields.

[0114] The above specific embodiments further illustrate the purpose, technical solutions and beneficial effects of the present disclosure. It should be understood that the above are only specific embodiments of the present disclosure and are not used to limit the present disclosure. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present disclosure shall be included in the protection scope of the present disclosure.

Claims

1.An imaging system based on an optical comb light source, comprising: an optical comb light source unit configured to provide a first optical comb light source; a gas absorption unit configured to load a gas to be measured, wherein the first optical comb light source passes through the gas to be measured to obtain a second optical comb light source; a light source processing unit, the light source processing unit comprising a collimation module and a filter module, configured to collimate and filter the second optical comb light source to obtain incident light; an interference unit, the interference unit comprising a Fizeau interferometer, the Fizeau interferometer comprising two flat plates coated with high reflectivity film surfaces, a wedge angle being formed between the two flat plates to divide the incident light into first and second exit light, for causing the incident light to interfere to form interference fringes; an imaging unit configured to image the interference fringes to obtain a fringe pattern; and an analysis unit configured to analyze the fringe pattern to obtain an analysis result, wherein the analysis result comprises a composition of the gas to be measured. 2.The imaging system of claim 1, wherein the optical comb light source unit comprises a chip integrated optical frequency comb. 3.The imaging system of claim 1, wherein the collimation module comprises a collimation mirror; and the filter module comprises a filter. 4.The imaging system of claim 1, wherein the imaging unit comprises a detector. 5.The imaging system of claim 4, wherein the detector is configured to detect a light signal of the interference fringes to obtain an interference pattern. 6.The imaging system of claim 4, wherein the detector comprises a photonic detector array. 7.An imaging method based on an optical comb light source, comprising: providing a first optical comb light source by using an optical comb light source unit; causing the first optical comb light source to pass through a gas absorption unit loaded with a gas to be measured to obtain a second optical comb light source; collimating and filtering the second optical comb light source by using a light source processing unit to obtain incident light, the light source processing unit comprising a collimation module and a filter module; causing the incident light to interfere to form interference fringes by using an interference unit, the interference unit comprising a Fizeau interferometer, the Fizeau interferometer comprising two flat plates coated with high reflectivity film surfaces, a wedge angle being formed between the two flat plates to divide the incident light into first and second exit light, for causing the incident light to interfere to form interference fringes; imaging the interference fringes by using an imaging unit to obtain a fringe pattern; and analyzing the fringe pattern by using an analysis unit to obtain an analysis result, wherein the analysis result comprises a composition of the gas to be measured. ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ The collimation module is configured to collimate the second optical comb light source and input the collimated second optical comb light source to the filter module. The filter module is configured to filter out the center pump frequency of the collimated second optical comb light source to form incident light entering the interference unit, and filter out the comb teeth on both sides of the center wavelength of the second optical comb light source based on a preset spectral range.

Images