Fourier transform spectrum equipment based on phase regulation and control and spectrum detection method

Abstract

The invention provides Fourier transform spectrum equipment based on phase regulation and control and a spectrum detection method, and relates to the technical field of spectrum measurement. The Fourier transform spectrum equipment comprises a light source module used for providing detection light; the spectroscope is used for splitting the detection light into first scanning light and first reference light; the scanning module is used for introducing phase delay linearly related to the light frequency into the first scanning light to obtain second scanning light, and providing the second scanning light for the sample through the spectroscope; the reference module is used for reflecting the first reference light to obtain second reference light and providing the second reference light for the sample through the spectroscope; the photoelectric detector is used for receiving the second scanning light acted on the sample and the second reference light acted on the sample to obtain a first interference pattern; and the processing module is used for processing the first interference spectrum to obtain a spectrum detection result of the sample.

Description

Technical Field

[0001] The present invention relates to the field of spectrum measurement technology, and more specifically, to a Fourier transform spectrum device based on phase regulation and a spectrum detection method. Background Art

[0002] Fourier transform spectroscopy (FTS) is an advanced optical detection technology based on the principles of optical interference, heterodyne detection, and Fourier transform. The FTS measurement system primarily consists of a Michelson interferometer, a broadband light source, a photodetector, and a HeNe reference laser. It offers advantages such as wide bandwidth, high resolution, and high sensitivity. It can also be combined with spatial scanning or coded apertures to achieve high-throughput spectral imaging. Therefore, FTS is widely used in fields such as chemical synthesis, biopharmaceuticals, food safety, and materials science for qualitative and quantitative analysis of substances.

[0003] Currently, FTS measurement systems in related technologies include high-speed vibration, step-scan, static interferometry, time-resolved frequency comb, and dual-beam comb types. These systems significantly improve the temporal resolution of FTS detection, enhancing real-time performance. However, these FTS measurement systems still have some shortcomings, preventing them from achieving both high-speed scanning and high spectral resolution. Summary of the Invention

[0004] In view of this, the present invention provides a Fourier transform spectroscopy device and a spectroscopy detection method based on phase control, which can achieve spectral detection with both high-speed scanning and high spectral resolution.

[0005] One aspect of the present invention provides a Fourier transform spectroscopy device based on phase control, comprising: a light source module for providing detection light; a spectroscope for splitting the detection light into a first scanning light and a first reference light; a scanning module for introducing a phase delay linearly related to the optical frequency into the first scanning light to obtain a second scanning light, and providing the second scanning light to the sample through the spectroscope, wherein the scanning module comprises a 4F optical path structure based on a preset focal length, and the 4F optical path structure comprises a grating, a first plane reflector, a spherical reflector and a scanning oscillator. The spherical reflector comprises a mirror, the focal length of the spherical reflector being the preset focal length, the grating being located at the front focal plane of the spherical reflector, and the scanning galvanometer being located at the back focal plane of the spherical reflector; a reference module being configured to reflect the first reference light to obtain the second reference light, and to provide the second reference light to the sample via the spectroscope; a photodetector being configured to receive the second scanning light after interacting with the sample and the second reference light after interacting with the sample to obtain a first interference pattern; and a processing module being configured to process the first interference pattern to obtain a spectral detection result of the sample.

[0006] According to an embodiment of the present invention, the 4F optical path structure is used to introduce the phase delay into the first scanning light to form a first light beam, convert the first light beam into the second scanning light, and provide the second scanning light to the sample.

[0007] According to an embodiment of the present invention, the above-mentioned grating is used to diffract and split the above-mentioned first scanning light to obtain a second light beam, and provide the above-mentioned second light beam to the above-mentioned first plane reflector; the above-mentioned first plane reflector is used to deflect the above-mentioned second light beam to provide the above-mentioned second light beam to the above-mentioned spherical reflector; the above-mentioned spherical reflector is used to collimate the above-mentioned second light beam to obtain a third light beam, and provide the above-mentioned third light beam to the above-mentioned scanning galvanometer mirror; the above-mentioned scanning galvanometer mirror is used to introduce the above-mentioned phase delay into the above-mentioned third light beam when it is in a rotating state to obtain the above-mentioned first light beam.

[0008] According to an embodiment of the present invention, the scanning galvanometer is also used to provide the first light beam to the spherical reflector; the spherical reflector is also used to converge the first light beam to obtain the second scanning light; the grating is used to deflect the second scanning light so as to provide the second scanning light to the sample.

[0009] According to an embodiment of the present invention, the scanning module further includes: a plane retroreflective mirror for correcting the incident optical path of the first scanning light and for correcting the outgoing optical path of the second scanning light; a second plane reflective mirror for deflecting the first scanning light to provide the first scanning light to the 4F optical path structure and for deflecting the second scanning light to provide the second scanning light to the sample.

[0010] According to an embodiment of the present invention, the scanning galvanometer includes a mirror body and a rotating shaft, and the mirror body is rotatably arranged on the rotating shaft; the above-mentioned device also includes a galvanometer driver, and the above-mentioned galvanometer driver is used to drive the rotating shaft to rotate in response to a control signal to drive the mirror body to rotate.

[0011] According to an embodiment of the present invention, the processing module is used to process the first interference pattern based on the optical frequency at the rotation axis of the scanning galvanometer, the phase delay of the optical frequency at the rotation axis, and the group delay to obtain the spectral detection result of the sample.

[0012] According to an embodiment of the present invention, the above-mentioned light source module is also used to provide calibration light; the above-mentioned spectrometer is also used to split the above-mentioned calibration light into a third scanning light and a third reference light; the above-mentioned scanning module is also used to process the above-mentioned third scanning light to obtain a fourth scanning light; the above-mentioned reference module is also used to reflect the above-mentioned third reference light to obtain a fourth reference light; the above-mentioned photodetector is also used to receive the above-mentioned fourth scanning light and the above-mentioned fourth reference light to obtain a second interference pattern; and the above-mentioned processing module is also used to determine the light frequency at the rotation axis of the above-mentioned scanning galvanometer, the phase delay of the light frequency at the rotation axis, and the above-mentioned group delay based on the above-mentioned second interference pattern.

[0013] Another aspect of the present invention provides a spectral detection method, comprising: using a spectroscope to split the detection light into a first scanning light and a first reference light; inputting the above-mentioned first scanning light into a scanning module to introduce a phase delay linearly related to the optical frequency into the above-mentioned first scanning light, thereby obtaining an emitted second scanning light, wherein the above-mentioned scanning module includes a 4F optical path structure based on a preset focal length, the above-mentioned 4F optical path structure includes a grating, a first plane reflector, a spherical reflector and a scanning galvanometer, the focal length of the above-mentioned spherical reflector is the above-mentioned preset focal length, the above-mentioned grating is located at the front focal plane of the above-mentioned spherical reflector, and the above-mentioned scanning galvanometer is located at the back focal plane of the above-mentioned spherical reflector; inputting the above-mentioned first reference light into a reference module to obtain an emitted second reference light; using a photodetector to receive the second scanning light after interacting with the sample and the second reference light after interacting with the sample to obtain a first interference pattern; and processing the above-mentioned first interference pattern to obtain a spectral detection result of the above-mentioned sample.

[0014] According to an embodiment of the present disclosure, the above method also includes: using a spectroscope to split the calibration light into a third scanning light and a third reference light; incident the above third scanning light on a scanning module to obtain a fourth scanning light; incident the above third reference light on a reference module to obtain a fourth reference light; using a photodetector to receive the above fourth scanning light and the above fourth reference light to obtain a second interference pattern; and based on the above second interference pattern, determining the light frequency at the rotation axis of the above scanning galvanometer, the phase delay of the light frequency at the rotation axis, and the group delay.

[0015] According to the embodiments of the present invention, high scanning speed can be achieved by utilizing high-speed mechanical scanning of the scanning galvanometer; by utilizing the high-performance high-frequency response of the scanning galvanometer, high-frequency large-angle rotation of hundreds of Hz to thousands of Hz can be performed, and a first interference pattern with high spectral resolution of hundreds of Hz to thousands of Hz can be obtained, thereby achieving both high-speed scanning and high spectral resolution of FTS measurement, and realizing dynamic scanning while scanning and displacing, breaking through the limitation of the maximum optical path difference and expanding the scope of application. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] The above and other objects, features and advantages of the present invention will become more apparent from the following description of the embodiments of the present invention with reference to the accompanying drawings.

[0017] Figure 1 A schematic diagram of a Fourier transform spectroscopy device based on phase control according to an embodiment of the present invention is shown.

[0018] Figure 2 A schematic diagram of a scanning module according to an embodiment of the present invention is shown.

[0019] Figure 3 A schematic diagram of a Fourier transform spectroscopy device based on phase control according to another embodiment of the present invention is shown. DETAILED DESCRIPTION

[0020] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. However, it should be understood that these descriptions are exemplary only and are not intended to limit the scope of the present invention. In the following detailed description, for ease of explanation, many specific details are set forth to provide a comprehensive understanding of embodiments of the present invention. However, it is apparent that one or more embodiments may also be implemented without these specific details. In addition, in the following description, descriptions of known structures and technologies are omitted to avoid unnecessary confusion of the concept of the present invention.

[0021] The terms used herein are only for describing specific embodiments and are not intended to limit the present invention. The terms "comprise", "include", etc. 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.

[0022] All terms used herein (including technical and scientific terms) have the meanings commonly understood by those skilled in the art unless otherwise defined. It should be noted that the terms used herein should be interpreted as having a meaning consistent with the context of this specification and should not be interpreted in an idealized or overly rigid manner.

[0023] When expressions such as "at least one of A, B, and C, etc." are used, they should generally be interpreted in accordance with the meaning commonly understood by those skilled in the art (for example, "a system having at least one of A, B, and C" should include but is not limited to a system having A alone, B alone, C alone, A and B, A and C, B and C, and / or A, B, C, etc.).

[0024] The basic measurement principle of an FTS measurement system is to use a voice coil motor (VCM) to drive the moving mirror of a scanning Michelson interferometer, thereby varying the phase difference between the reference beam and the scanning beam. The interference pattern is captured by a photodetector and then Fourier transformed to produce a spectrum. The resolution of the resulting spectrum is inversely proportional to the maximum optical path difference (OPD) introduced by the VCM: a larger maximum OPD results in higher spectral resolution. However, the scanning mechanism based on a VCM exhibits poor high-frequency response and cannot generate a sufficiently large OPD under high-frequency drive signal excitation. Therefore, conventional FTS measurement systems often require increasing the scanning frequency at the expense of spectral resolution. Furthermore, VCMs are prone to jitter at high frequencies, introducing phase noise and distorting the interference pattern, severely degrading spectral quality. To avoid these issues, slow scanning speeds are typically used to ensure the VCM can smoothly scan over long distances. This makes FTS instruments generally suitable for measuring steady-state spectra but unsuitable for spectral analysis of fast dynamic processes.

[0025] Currently, FTS measurement systems in related technologies include various types, such as high-speed vibration, step-scan, static interferometry, time-resolved frequency comb, and dual-beam comb. These systems significantly improve the time resolution capability of FTS detection, thereby enhancing real-time performance. However, related FTS measurement systems still have the following problems:

[0026] (a) Insufficient maximum optical path difference: High-speed vibration FTS measurement systems use high-frequency resonant devices such as ultrasonic vibrators to replace the voice coil motors in traditional FTS measurement systems. This improves the high-frequency maximum displacement output to a certain extent and enables high-speed interferogram scanning. However, due to the limitations of their inherent mechanical properties and driving power, the maximum optical path difference that high-frequency resonant devices can provide is still insufficient, resulting in low spectral resolution. It is difficult to achieve both high-speed scanning and high spectral resolution. Therefore, it is only suitable for fast dynamic process analysis and imaging applications where spectral resolution requirements are not high.

[0027] (b) Suitable only for repeatable process measurements: Step-scan FTS and time-resolved frequency comb FTS systems utilize an "acquire first, shift later" scanning approach (unlike the "acquire while shifting" approach of traditional FTS systems). This fully leverages the sampling rate of photoelectric detectors while simultaneously scanning across large optical path differences, achieving both real-time performance and spectral resolution. However, this "acquire first, shift later" scanning approach requires a high degree of repeatability in the process being measured, making it unsuitable for spectral measurements of dynamic processes with fast response times, short durations, and high randomness.

[0028] (c) Spectral resolution and spectral range are severely limited by hardware: Static interferometric FTS measurement systems typically use a Sagnac interferometer to generate interference, combined with lenses and photodetector arrays to implement hardware Fourier transform and spectral acquisition. Static interferometric FTS measurement systems are a type of FTS measurement system that does not require mechanical scanning. Their spectral measurement speed is relatively high, typically determined by the frame rate of the photodetector array. However, due to the large pixel pitch of the photodetector array, the spectral resolution of static interferometric FTS measurement systems is relatively low, generally no better than 10 nm, and sometimes even worse than 100 nm. In addition, photodetector arrays that respond to other wavelengths are relatively rare and expensive, so static interferometric FTS measurement systems typically use photodetector arrays in the visible light band, which to some extent limits their application range.

[0029] (d) The system is too sophisticated and complex: The dual-comb FTS measurement system uses two coherent optical frequency combs with slightly different repetition frequencies to directly generate a beat pulse sequence (i.e., an interferogram) through heterodyne interference. Spectral information can be obtained by Fourier transforming the beat pulse sequence. The dual-comb FTS measurement system is a mechanical scanning-free FTS measurement system with extremely high spectral resolution and scanning frequency. However, compared with the FTS measurement system based on the Michelson interferometer, the dual-comb FTS measurement system requires a more sophisticated and complex optical system to generate and maintain the mutually coherent dual combs, and its debugging difficulty and hardware cost are both higher. In addition, the dual-comb FTS measurement system is an active spectral measurement system that must use a mutually coherent dual comb as a light source to operate. Therefore, its flexibility and adaptability are relatively poor, and it is not as good as the Michelson FTS measurement system.

[0030] Therefore, the FTS measurement system in the related art still has some shortcomings and cannot achieve spectral detection with both high-speed scanning and high spectral resolution.

[0031] The embodiments of the present invention provide a Fourier transform spectroscopy device and a spectroscopy detection method based on phase control, in order to solve at least one of the above technical problems.

[0032] Figure 1A schematic diagram of a Fourier transform spectroscopy device based on phase control according to an embodiment of the present invention is shown.

[0033] like Figure 1 As shown, the Fourier transform spectroscopy device based on phase control includes a light source module 1, a scanning module 2, a reference module 3, a spectroscope 4, a photodetector 6 and a processing module 7.

[0034] According to an embodiment of the present invention, the light source module 1 is used to provide detection light. The spectrometer 4 is used to split the detection light into a first scanning light and a first reference light. The scanning module 2 is used to introduce a phase delay linearly related to the light frequency into the first scanning light to obtain a second scanning light, and provide the second scanning light to the sample 5 via the spectrometer 4. The reference module 3 is used to reflect the first reference light to obtain a second reference light, and provide the second reference light to the sample 5 via the spectrometer 4. The photodetector 6 is used to receive the second scanning light after acting on the sample 5 and the second reference light after acting on the sample 5 to obtain a first interference pattern. The processing module 7 is used to process the first interference pattern to obtain a spectral detection result of the sample 5.

[0035] In one embodiment, the light source module 1, the scanning module 2, the reference module 3, and the spectroscope 4 form a Michelson interferometer. The light source module 1 may include a broadband light source to generate detection light with a first bandwidth. The spectroscope 4 may be a cubic spectroscope prism that can realize the spectrometry required for amplitude-division interference of the Michelson interferometer. The spectroscope 4 may be a cubic spectroscope prism with a surface anti-reflection film and a non-polarizing spectroscope film, and the working bands of the surface anti-reflection film and the non-polarizing spectroscope film are within the light-emitting band of the light source module 1. The sample 5 may be set on the sample holder. The photodetector 6 may be an indium gallium arsenide photodiode, the response band may include 800nm-1700nm, and the photosensitive surface diameter may include 3mm-6mm. The interference light signals of the second scanning light after acting on the sample 5 and the second reference light after acting on the sample 5 can be converted into electrical signals to obtain a first interference pattern.

[0036] Phase delay is the phase difference caused by different refractive indices or path lengths during wave propagation. In optics, phase delay is typically calculated as the product of the optical path difference (OPD) and the wave number. The optical path difference refers to the difference in distance traveled by light along different paths. In interference experiments, the optical path difference between two beams of light causes a phase difference when they meet, forming interference fringes. The wave number is the ratio of the wave's frequency to its velocity, indicating the number of wave cycles per unit distance. By measuring phase delay, the OPD can be precisely measured.

[0037] like Figure 1 As shown, the scanning module 2 includes a 4F optical path structure based on a preset focal length.

[0038] According to an embodiment of the present invention, Figure 1As shown, the 4F optical path structure includes a grating 201, a first plane reflector 202, a spherical reflector 203 and a scanning galvanometer mirror 204. The focal length of the spherical reflector 203 is a preset focal length F. The grating 201 is located at the front focal plane of the spherical reflector 203, and the scanning galvanometer mirror 204 is located at the back focal plane of the spherical reflector 203.

[0039] According to the embodiments of the present invention, high scanning speed can be achieved by utilizing high-speed mechanical scanning of the scanning galvanometer; by utilizing the high-performance high-frequency response of the scanning galvanometer, high-frequency large-angle rotation of hundreds of Hz to thousands of Hz can be performed, and a first interference pattern with high spectral resolution of hundreds of Hz to thousands of Hz can be obtained, thereby achieving both high-speed scanning and high spectral resolution of FTS measurement, and realizing dynamic scanning while scanning and displacing, breaking through the limitation of the maximum optical path difference and expanding the scope of application.

[0040] The phase-controlled Fourier transform spectroscopy device of the embodiment of the present invention can adjust the scanning speed, spectral resolution, and spectral range of the first interference pattern by debugging or replacing the device parameters of the scanning module to meet the requirements of different spectral analysis tasks.

[0041] The phase-controlled Fourier transform spectroscopy device of the embodiment of the present invention belongs to a Michelson interferometer FTS measurement system, which has low hardware complexity and low cost, and is easy to develop, assemble, debug, repair and upgrade.

[0042] In one embodiment, grating 201 may be a blazed grating, which maximizes spectral intensity when detecting in a predetermined direction. The blazed grating may be a plane grating with a groove density of 300-1200 lp / mm and a blaze wavelength within the wavelength band of the detection light. Spherical reflector 203 may be a plano-concave spherical reflector, which may be an aluminum plano-concave spherical reflector with a focal length of 30-200 mm. First plane reflector 202 may be an aluminum plane reflector.

[0043] The grating 201 diffracts and splits the first scanning light, and the spherical reflector 203 converges the third light beam onto the surface of the scanning galvanometer 204 to form a linear focal spot (hereinafter referred to as a linear focal spot) along the radial direction of the rotation axis of the scanning galvanometer 204.

[0044] The diffraction angle of the grating 201 and the wavelength of the incident light satisfy the grating equation.

[0045] (1);

[0046] (2);

[0047] in, and Represents wavelength Beam and wavelength The first-order grating diffraction angle of the beam is, represents the grating line density of the grating 201, represents the incident angle of the grating 201, Indicates the wavelength of light corresponding to a certain position in the linear focal spot, Indicates the wavelength of light at the rotation axis of the scanning galvanometer mirror 204 .

[0048] Figure 2 A schematic diagram of a scanning module according to an embodiment of the present invention is shown.

[0049] According to an embodiment of the present invention, Figure 1 and Figure 2 As shown, the 4F optical path structure is used to introduce a phase delay in the first scanning light to form a first light beam, convert the first light beam into a second scanning light, and provide the second scanning light to the sample 5.

[0050] According to an embodiment of the present invention, Figure 2 As shown, grating 201 is used to diffract and split the first scanning light to obtain a second light beam, and provides the second light beam to first plane reflector 202. First plane reflector 202 is used to deflect the second light beam to provide the second light beam to spherical reflector 203. Spherical reflector 203 is used to collimate the second light beam to obtain a third light beam, and provides the third light beam to scanning galvanometer 204. Scanning galvanometer 204 is used to introduce a phase delay in the third light beam when in a rotating state to obtain the first light beam.

[0051] When the scanning galvanometer 204 is deflected, different positions on the surface of the scanning galvanometer 204 have different linear displacements along the radial direction of the rotation axis. Therefore, the wavelength Beam and wavelength The optical path difference of the beam It can be expressed as:

[0052] (3);

[0053] in, represents the focal length of the spherical reflector 203, represents the rotational angular velocity of the scanning galvanometer 204, Indicates time.

[0054] because and is much smaller than 1, and is much smaller than 1, so combining formula (1) and formula (2) can simplify formula (3) to obtain the optical path difference The simplified expression of :

[0055] (4);

[0056] in, represents the speed of light, and Represents wavelength Beam and wavelength The light frequency corresponding to the beam.

[0057] When the scanning galvanometer 204 is in a rotating state, a phase delay that is linearly related to the optical frequency is introduced into the third light beam to obtain the first light beam.

[0058] wavelength The wavelength of the beam The phase delay of the beam It can be expressed as:

[0059] (5).

[0060] According to the relationship between group delay and phase delay, group delay is the derivative of phase delay with respect to frequency. It can be expressed as:

[0061] (6).

[0062] According to an embodiment of the present invention, Figure 1 and Figure 2 As shown, the scanning galvanometer 204 is also used to provide a first light beam to the spherical reflector 203. The spherical reflector 203 is also used to converge the first light beam to obtain a second scanning light. The grating 201 is used to deflect the second scanning light so as to provide the second scanning light to the sample 5.

[0063] According to an embodiment of the present invention, Figure 2 As shown, the scanning module further includes a plane retroreflective mirror 205 and a second plane reflective mirror 206 .

[0064] like Figure 1 and Figure 2 As shown, the plane retroreflective mirror 205 is used to correct the incident optical path of the first scanning light and to correct the outgoing optical path of the second scanning light. The second plane reflective mirror 206 is used to deflect the first scanning light to provide the first scanning light to the 4F optical path structure and to deflect the second scanning light to provide the second scanning light to the sample 5.

[0065] According to an embodiment of the present invention, Figure 2 As shown, the scanning galvanometer 204 includes a mirror body and a rotating shaft, wherein the mirror body is rotatably arranged on the rotating shaft. The Fourier transform spectroscopy device based on phase control also includes a galvanometer driver, which is used to drive the rotating shaft to rotate in response to a control signal to drive the mirror body to rotate.

[0066] In one embodiment, the mirror body can be a silver-plated galvanometer mirror with a mirror width of 10 mm to 60 mm and a response bandwidth of 1 kHz. The maximum rotation angle of the mirror body on the rotation axis can be ±22.5°, which matches the galvanometer mirror driver.

[0067] According to an embodiment of the present invention, the first interference pattern is a difference frequency spectrum of the optical frequencies corresponding to the relative position of the scanning mirror's rotation axis. By varying the parameters of the optical components in the 4F optical path structure, the relative position of the scanning mirror and the linear focal spot, and the angular frequency of the scanning mirror's rotation, the phase delay and group delay introduced into the first scanning light are adjusted for spectral detection, enabling FTS measurement based on the principle of phase control.

[0068] Theoretical maximum resolution of the first interference pattern It can be expressed as:

[0069] (7);

[0070] in, Indicates the maximum deflection angle of the scanning galvanometer within one motion cycle; Indicates group delay Maximum value.

[0071] According to an embodiment of the present invention, Figure 1 and Figure 2 As shown, the processing module 7 is used to process the first interference pattern based on the optical frequency at the rotation axis of the scanning galvanometer 204, the phase delay of the optical frequency at the rotation axis, and the group delay to obtain the spectrum detection result of the sample 5.

[0072] The light frequency is The electric field function of the second scanning light Frequency domain expression of and the electric field function of the second reference light Frequency domain expression of It can be expressed as:

[0073] (8);

[0074] (9);

[0075] in, represents the electric field function of the first scanning light and the first reference light output by the spectroscope 4, It represents the group delay introduced by the total optical path of scanning module 2 and reference module 3.

[0076] The electric field function of the second scanning light and the electric field function of the second reference light Perform inverse Fourier transform to obtain the electric field function of the second scanning light The time domain expression of and the electric field function of the second reference light The time domain expression of :

[0077] (10);

[0078] (11);

[0079] in, Represents the inverse Fourier transform operation.

[0080] The first interference pattern is obtained by the interference of the second scanning light after interacting with the sample 5 and the second reference light after interacting with the sample 5 at the photosensitive surface of the photodetector 6. The interference intensity of the first interference pattern is a function of the group delay. The first interference pattern carries the spectral information of the sample 5. It can be expressed as:

[0081] (12);

[0082] Among them, Replace with To simplify the derivation process without affecting the final result; express The complex conjugate of yes The time domain expression of .

[0083] Perform Fourier transform on the first interference pattern to obtain the heterodyne spectrum of sample 5 , which can be expressed as:

[0084] (13);

[0085] in, for propose The remainder after Represents the Fourier transform operation.

[0086] According to an embodiment of the present invention, Figure 1 and Figure 2 As shown, the light source module 1 is also used to provide calibration light. The spectrometer 4 is also used to split the calibration light into a third scanning light and a third reference light. The scanning module 2 is also used to process the third scanning light to obtain a fourth scanning light. The reference module 3 is also used to reflect the third reference light to obtain a fourth reference light. The photodetector 6 is also used to receive the fourth scanning light and the fourth reference light to obtain a second interference pattern. The processing module 7 is also used to determine the optical frequency at the rotation axis of the scanning galvanometer 204, the phase delay of the optical frequency at the rotation axis, and the group delay based on the second interference pattern.

[0087] In one embodiment, the light source module 1 may further include a calibration laser to generate calibration light having a second bandwidth, wherein the second bandwidth is within the range of the first bandwidth.

[0088] The photodetector 6, high-speed digitizer 8, galvanometer driver 9 and control host are powered on and reset. The control host is used to control the light source module 1 to be turned off, the mirror movement of the scanning galvanometer 204 to be turned off, and the sampling parameters of the high-speed digitizer 8 are configured.

[0089] After all instruments and equipment are assembled and initialized, calibration is required before starting the measurement for the first time. The first interference pattern is the optical frequency relative to the axis of the scanning galvanometer. The difference frequency spectrum needs to be accurately measured The value of .

[0090] In an embodiment of the present invention, the processing module 7 controls the light source module 1 to provide calibration light, and then controls the galvanometer driver to drive the mirror body to rotate to obtain a second interference pattern. The processing module 7 determines the light frequency at the rotation axis of the scanning galvanometer 204 based on the second interference pattern. , the optical frequency at the axis Phase delay, and group delay.

[0091] The processing module 7 controls the light source module 1 to provide detection light, and then controls the galvanometer driver to drive the mirror body to rotate to obtain the first interference pattern. The processing module 7 is based on the light frequency at the rotation axis of the scanning galvanometer 204. , the optical frequency at the axis The processing module 7 performs Fourier transform on the calibrated first interference pattern to determine the optical frequency at the rotation axis of the scanning galvanometer 204. The difference frequency spectrum is shifted toward high frequency direction , and obtain the spectral detection results of sample 5.

[0092] According to the embodiment of the present invention, it is not necessary to perform optical path sampling based on the helium-neon laser, and only one calibration data (the optical frequency at the rotation axis of the scanning galvanometer 204) needs to be performed after the Fourier transform spectroscopy device based on phase control in the embodiment of the present invention is assembled. , the optical frequency at the axis By collecting the phase delay and group delay of the first interference pattern of all detection lights measured subsequently, the phase delay and group delay can be calibrated.

[0093] Figure 3 A schematic diagram of a Fourier transform spectroscopy device based on phase control according to another embodiment of the present invention is shown.

[0094] like Figure 3 As shown, a Fourier transform spectroscopy device based on phase control according to another embodiment of the present invention includes a light source module 1, a scanning module 2, a reference module 3, a spectroscope 4, a photodetector 6, a processing module 7, a high-speed digitizer 8 and a galvanometer driver 9.

[0095] like Figure 3 As shown, in one embodiment, the light source module 1 may include a broadband light source 101, a calibration laser 102, a fiber combiner and a fiber collimator 104. The broadband light source 101 may generate detection light, and the calibration laser 102 may generate calibration light. The detection light and the calibration light may enter the fiber collimator 104 through the fiber combiner and be emitted as parallel light. In one embodiment, the broadband light source 101 may be a fiber-coupled superluminescent diode with a central wavelength of 800nm-1700nm and a spectral bandwidth of 40nm-100nm. The calibration laser 102 may be a fiber-coupled narrow-linewidth laser with a wavelength within the emission band of the broadband light source 101. The operating bands of the fiber combiner and the fiber collimator 104 may match the emission band of the broadband light source 101.

[0096] like Figure 3 As shown, in one embodiment, reference module 3 may include a neutral density filter 301 and a plane retroreflective mirror 302. Neutral density filter 301 may be an absorptive neutral density filter with an optical density of 0.1-2, which can adjust the intensity of the second reference light. Proper selection of the optical density can ensure that the second reference light of reference module 3 has an intensity similar to that of the second scanning light of scanning module 2. In one embodiment, plane retroreflective mirror 302 may be an aluminum plane reflector.

[0097] like Figure 3 As shown, in one embodiment, the beam splitter 4 may be coated with a surface anti-reflection film and a non-polarization beam splitting film, and the operating wavelength band is within the emission wavelength band of the broadband light source 101 .

[0098] like Figure 3 As shown, in one embodiment, the processing module 7 can be a control host, controlling the light source module 1, high-speed digitizer 8, and galvanometer driver 9 via a bus. The processing module 7 can control the switching and power adjustment of the broadband light source 101 and the calibration laser 102. The processing module 7 can also control the configuration of the high-speed digitizer 8 and the reading of sampling results. The processing module 7 can also control the galvanometer driver 9 to control the movement of the scanning galvanometer 204.

[0099] In one embodiment, the high-speed digitizer 8 can sample and quantize the electrical signal output by the photodetector 6. The high-speed digitizer 8 can be a high-speed analog acquisition card with a maximum sampling rate of no less than 125 MHz, a quantization bit depth of no less than 12 bits, and an external trigger function.

[0100] The present invention also provides a spectral detection method, including: using a spectrometer to split the detection light into a first scanning light and a first reference light; inputting the first scanning light into a scanning module to introduce a phase delay linearly related to the light frequency into the first scanning light, thereby obtaining an emitted second scanning light, wherein the scanning module includes a 4F optical path structure based on a preset focal length, the 4F optical path structure includes a grating, a first plane reflector, a spherical reflector and a scanning galvanometer, the focal length of the spherical reflector is the preset focal length, the grating is located at the front focal plane of the spherical reflector, and the scanning galvanometer is located at the back focal plane of the spherical reflector; inputting the first reference light into the reference module to obtain an emitted second reference light; using a photodetector to receive the second scanning light after interacting with the sample and the second reference light after interacting with the sample to obtain a first interference pattern; and processing the first interference pattern to obtain a spectral detection result of the sample.

[0101] According to an embodiment of the present invention, the spectral detection method also includes: using a spectroscope to split the calibration light into a third scanning light and a third reference light; incident the third scanning light on a scanning module to obtain a fourth scanning light; incident the third reference light on a reference module to obtain a fourth reference light; using a photodetector to receive the fourth scanning light and the fourth reference light to obtain a second interference pattern; and based on the second interference pattern, determining the light frequency at the rotation axis of the scanning galvanometer, the phase delay of the light frequency at the rotation axis, and the group delay.

[0102] The above describes embodiments of the present invention. However, these embodiments are for illustrative purposes only and are not intended to limit the scope of the present invention. Although each embodiment has been described separately above, this does not mean that the measures in each embodiment cannot be advantageously used in combination. Without departing from the scope of the present invention, those skilled in the art may make various substitutions and modifications, which should all fall within the scope of the present invention.

Claims

1. A Fourier transform spectroscopy device based on phase control, characterized in that: include: A light source module, used for providing detection light; a beam splitter, configured to split the detection light into a first scanning light and a first reference light; a scanning module, configured to introduce a phase delay linearly related to the optical frequency into the first scanning light to obtain a second scanning light, and provide the second scanning light to the sample via the spectroscope, wherein the scanning module comprises a 4F optical path structure based on a preset focal length, the 4F optical path structure comprising a grating, a first plane reflector, a spherical reflector, and a scanning galvanometer mirror, the focal length of the spherical reflector being the preset focal length, the grating being located at a front focal plane of the spherical reflector, and the scanning galvanometer mirror being located at a back focal plane of the spherical reflector; a reference module, configured to reflect the first reference light to obtain a second reference light, and provide the second reference light to the sample via the spectroscope; a photodetector, configured to receive the second scanning light after interacting with the sample and the second reference light after interacting with the sample, to obtain a first interference pattern; and A processing module is used to process the first interference pattern to obtain a spectrum detection result of the sample.

2. The Fourier transform spectroscopy device according to claim 1, characterized in that The 4F optical path structure is used to introduce the phase delay into the first scanning light to form a first light beam, convert the first light beam into the second scanning light, and provide the second scanning light to the sample.

3. The Fourier transform spectroscopy device according to claim 2, characterized in that The grating is used to diffract and split the first scanning light to obtain a second light beam, and provide the second light beam to the first plane reflector; The first plane reflector is used to deflect the second light beam to provide the second light beam to the spherical reflector; The spherical reflector is used to collimate the second light beam to obtain a third light beam, and provide the third light beam to the scanning galvanometer; The scanning galvanometer is used to introduce the phase delay into the third light beam when in a rotating state to obtain the first light beam.

4. The Fourier transform spectroscopy device according to claim 2, characterized in that The scanning galvanometer is further used to provide the first light beam to the spherical reflector; The spherical reflector is further used to converge the first light beam to obtain the second scanning light; The grating is used to deflect the second scanning light so as to provide the second scanning light to the sample.

5. The Fourier transform spectroscopy device according to claim 1, characterized in that The scanning module also includes: a plane retroreflecting mirror, used to correct the incident optical path of the first scanning light and to correct the outgoing optical path of the second scanning light; The second plane reflective mirror is used to deflect the first scanning light to provide the first scanning light to the 4F optical path structure, and to deflect the second scanning light to provide the second scanning light to the sample.

6. The Fourier transform spectroscopy device according to claim 1, characterized in that The scanning galvanometer includes a mirror body and a rotating shaft, and the mirror body is rotatably arranged on the rotating shaft; The device further includes a galvanometer driver, which is configured to drive the rotating shaft to rotate in response to a control signal, so as to drive the mirror body to rotate.

7. The Fourier transform spectroscopy device according to claim 6, characterized in that The processing module is used to process the first interference pattern based on the optical frequency at the rotation axis of the scanning galvanometer, the phase delay of the optical frequency at the rotation axis, and the group delay to obtain the spectrum detection result of the sample.

8. The Fourier transform spectroscopy device according to claim 7, characterized in that The light source module is also used to provide calibration light; The beam splitter is further used to split the calibration light into a third scanning light and a third reference light; The scanning module is further configured to process the third scanning light to obtain a fourth scanning light; The reference module is further configured to reflect the third reference light to obtain a fourth reference light; The photodetector is further configured to receive the fourth scanning light and the fourth reference light to obtain a second interference pattern; and The processing module is further configured to determine the optical frequency at the rotation axis of the scanning galvanometer, the phase delay of the optical frequency at the rotation axis, and the group delay based on the second interference pattern.

9. A spectrum detection method, characterized in that: include: Splitting the detection light into a first scanning light and a first reference light by using a beam splitter; The first scanning light is incident on a scanning module to introduce a phase delay linearly related to the optical frequency into the first scanning light, thereby obtaining an emitted second scanning light, wherein the scanning module includes a 4F optical path structure based on a preset focal length, the 4F optical path structure including a grating, a first plane reflector, a spherical reflector, and a scanning galvanometer mirror, the focal length of the spherical reflector being the preset focal length, the grating being located at a front focal plane of the spherical reflector, and the scanning galvanometer mirror being located at a back focal plane of the spherical reflector; injecting the first reference light into a reference module to obtain an emitted second reference light; Using a photodetector to receive the second scanning light after interacting with the sample and the second reference light after interacting with the sample, to obtain a first interference pattern; and The first interference pattern is processed to obtain a spectrum detection result of the sample.

10. The spectrum detection method according to claim 9, characterized in that: The method further comprises: Splitting the calibration light into a third scanning light and a third reference light using a beam splitter; injecting the third scanning light into a scanning module to obtain a fourth scanning light; injecting the third reference light into a reference module to obtain a fourth reference light; receiving the fourth scanning light and the fourth reference light using a photodetector to obtain a second interference pattern; and Based on the second interference pattern, the optical frequency at the rotation axis of the scanning galvanometer, the phase delay of the optical frequency at the rotation axis, and the group delay are determined.

Images