Resonator tuning method, apparatus, readable storage medium and program product

Abstract

The application relates to a resonant cavity adjusting method and device, a readable storage medium and a program product, relates to the technical field of laser absorption spectroscopy, and can improve the resonant cavity adjusting efficiency. The resonant cavity corresponds to different finenesses of light beams with different polarization states, and the coupling rate of the light beams with different polarization states and the resonant cavity increases with the decrease of the finenesses. The method comprises the following steps: based on a first fineness, a reference light beam is obtained and coupled into a resonant cavity to be adjusted; a second mode image formed by the coupling of the reference light beam and the resonant cavity is obtained; the second mode image is used for guiding the adjustment of alignment parameters of the resonant cavity until the second mode image presents a second basic mode feature; then, a target light beam is switched, a first mode image formed by the coupling of the target light beam and the resonant cavity is obtained, and based on the image, the incident parameters of the target light beam are adjusted until the first mode image presents a first basic mode feature, and the adjustment of the resonant cavity is completed.

Description

Technical Field

[0001] This application relates to the field of laser absorption spectroscopy technology, and in particular to a mode-reference-based resonant cavity assembly and tuning method, apparatus, computer equipment, computer-readable storage medium, and computer program product. Background Technology

[0002] In existing cavity ring-down spectroscopy (CRDS) techniques, the assembly and adjustment of the resonant cavity is a crucial step in achieving high-sensitivity measurements. The core objective is to precisely match the incident laser with the resonant cavity to the fundamental mode, as this minimizes energy loss and maximizes the ring-down time. Most existing assembly and adjustment methods rely on monitoring the intensity of the mode signal to determine whether fundamental mode matching has been achieved; that is, they assume that the strongest signal corresponds to the presence of the fundamental mode.

[0003] However, this method has significant drawbacks: on the one hand, the signal strength of some low-order modes, although lower than that of the fundamental mode, is much higher than that of other high-order modes, making them easily misidentified as the fundamental mode during adjustment, affecting the final assembly and adjustment accuracy. On the other hand, for high-precision polarization resonators with higher sensitivity requirements, the detector often cannot detect any effective mode signal before the fundamental mode resonance is formed, making it impossible for technicians to determine the current coupling state, resulting in low efficiency in the assembly and adjustment process. Summary of the Invention

[0004] Therefore, it is necessary to provide a mode-reference-based resonant cavity assembly and tuning method, apparatus, computer equipment, computer-readable storage medium, and computer program product to address the aforementioned technical problems.

[0005] In a first aspect, this application provides a mode-reference-based resonant cavity assembly and tuning method, wherein the resonant cavity has different levels of fineness corresponding to beams with different polarization states, and the coupling rate between the beams with different polarization states and the resonant cavity increases as the fineness decreases; the method includes:

[0006] Based on the first precision corresponding to the target beam in the first polarization state, a reference beam in the second polarization state is obtained, and the reference beam is coupled into the resonant cavity to be assembled and adjusted; the target beam includes the beam used by the resonant cavity after assembly and adjustment, and the second precision corresponding to the reference beam is less than the first precision of the target beam;

[0007] A second mode image is acquired by coupling the reference beam with the resonant cavity; the second mode image is used to guide the adjustment of the alignment parameters of the resonant cavity until the second mode image presents the corresponding second fundamental mode characteristics.

[0008] After presenting the second fundamental mode feature, the reference beam is switched to the target beam to obtain a first mode image formed by the coupling of the target beam with the resonant cavity;

[0009] Based on the first mode image, the incident parameters of the target beam are adjusted until the first mode image presents the corresponding first fundamental mode characteristics, thus completing the assembly and adjustment of the resonant cavity.

[0010] In one embodiment, before obtaining the reference beam of the second polarization state based on the first precision corresponding to the target beam of the first polarization state, the method further includes:

[0011] Acquire the beam of the indicator light source and use the beam of the indicator light source to pre-align the geometric center of the resonant cavity;

[0012] The reference beam and the beam of the indicator light source are coaxially combined so that the reference beam propagates along the pre-aligned path.

[0013] In one embodiment, acquiring the second-mode image formed by the coupling of the reference beam and the resonant cavity includes:

[0014] A periodic scanning signal is acquired, and the cavity length of the resonant cavity is controlled to change periodically according to the scanning signal so that the reference beam is coupled in the resonant cavity to form resonance;

[0015] During the periodic change of the cavity length of the resonant cavity, multiple second-mode images of the reference beam at resonance are acquired.

[0016] In one embodiment, the resonant cavity includes a plurality of cavity mirrors, one of which is connected to a piezoelectric ceramic plate driver;

[0017] The step of controlling the cavity length of the resonant cavity to periodically change according to the scanning signal so that the reference beam couples and forms resonance in the resonant cavity includes:

[0018] The scanning signal is input to the piezoelectric ceramic plate driver, which drives the piezoelectric ceramic plate to extend and retract according to the scanning signal, so that when the cavity length of the resonant cavity and the wavelength of the reference beam meet the preset phase matching condition, the reference beam couples in the resonant cavity to form resonance.

[0019] In one embodiment, adjusting the incident parameters of the target beam based on the first mode image until the first mode image exhibits the corresponding first fundamental mode characteristics, thereby completing the assembly and adjustment of the resonant cavity, includes:

[0020] The system identifies whether the first-mode image after the target beam is coupled with the resonant cavity displays any abnormalities; the abnormalities include higher-order mode spots and non-resonant spots.

[0021] In the event of an anomaly, the incident parameters associated with the resonant cavity are adjusted until the first mode image exhibits the corresponding first fundamental mode characteristics.

[0022] In one embodiment, after the first pattern image presents the corresponding first fundamental mode feature, it further includes:

[0023] Acquire the output signal after the target beam is coupled with the resonant cavity;

[0024] If the value of the output signal is greater than the preset beam truncation threshold, the target beam is truncated, and the output signal after the target beam is truncated is obtained.

[0025] Based on the output signal after the target beam is truncated, the decay time of the target beam is determined to confirm that the current resonant cavity assembly is complete.

[0026] In one embodiment, the second level of fineness and the first level of fineness are determined by the following steps:

[0027] The first level of precision is determined based on the first reflectivity of the target beam in the first polarization state; the second level of precision is determined based on the second reflectivity of the cavity mirror of the resonant cavity for the reference beam in the second polarization state; the first reflectivity is higher than the second reflectivity.

[0028] Secondly, this application also provides a mode-reference-based resonant cavity assembly and adjustment device, wherein the resonant cavity has different levels of fineness corresponding to beams of different polarization states, and the coupling rate between the beams of different polarization states and the resonant cavity increases as the fineness decreases; the device includes:

[0029] A reference beam coupling module is used to obtain a reference beam in a second polarization state based on a first fineness corresponding to a target beam in a first polarization state, and to couple the reference beam into the resonant cavity to be assembled and adjusted; the target beam includes the beam used by the resonant cavity after assembly and adjustment, and the second fineness corresponding to the reference beam is less than the first fineness of the target beam;

[0030] A reference beam resonance adjustment module is used to acquire a second mode image formed by the coupling of the reference beam and the resonant cavity; the second mode image is used to guide the adjustment of the alignment parameters of the resonant cavity until the second mode image presents the corresponding second fundamental mode characteristics;

[0031] The target beam coupling module is used to switch the reference beam to the target beam after presenting the second fundamental mode feature, and to obtain a first mode image formed after the target beam is coupled with the resonant cavity;

[0032] The target beam resonance adjustment module is used to adjust the incident parameters of the target beam based on the first mode image until the first mode image presents the corresponding first fundamental mode characteristics, thereby completing the assembly and adjustment of the resonant cavity.

[0033] Thirdly, this application also provides an optical system for gas detection, wherein the resonant cavity has different levels of precision for light beams with different polarization states, and the coupling rate between the light beams with different polarization states and the resonant cavity increases as the precision decreases; it includes a memory and a processor, wherein the memory stores a computer program, and the processor executes the computer program to perform the following steps:

[0034] Based on the first precision corresponding to the target beam in the first polarization state, a reference beam in the second polarization state is obtained, and the reference beam is coupled into the resonant cavity to be assembled and adjusted; the target beam includes the beam used by the resonant cavity after assembly and adjustment, and the second precision corresponding to the reference beam is less than the first precision of the target beam;

[0035] A second mode image is acquired by coupling the reference beam with the resonant cavity; the second mode image is used to guide the adjustment of the alignment parameters of the resonant cavity until the second mode image presents the corresponding second fundamental mode characteristics.

[0036] After presenting the second fundamental mode feature, the reference beam is switched to the target beam to obtain a first mode image formed by the coupling of the target beam with the resonant cavity;

[0037] Based on the first mode image, the incident parameters of the target beam are adjusted until the first mode image presents the corresponding first fundamental mode characteristics, thus completing the assembly and adjustment of the resonant cavity.

[0038] Fourthly, this application also provides a computer-readable storage medium, wherein the resonant cavity has different levels of fineness corresponding to beams of different polarization states, and the coupling rate between the beams of different polarization states and the resonant cavity increases as the fineness decreases; a computer program is stored thereon, and when the computer program is executed by a processor, it performs the following steps:

[0039] Based on the first precision corresponding to the target beam in the first polarization state, a reference beam in the second polarization state is obtained, and the reference beam is coupled into the resonant cavity to be assembled and adjusted; the target beam includes the beam used by the resonant cavity after assembly and adjustment, and the second precision corresponding to the reference beam is less than the first precision of the target beam;

[0040] A second mode image is acquired by coupling the reference beam with the resonant cavity; the second mode image is used to guide the adjustment of the alignment parameters of the resonant cavity until the second mode image presents the corresponding second fundamental mode characteristics.

[0041] After presenting the second fundamental mode feature, the reference beam is switched to the target beam to obtain a first mode image formed by the coupling of the target beam with the resonant cavity;

[0042] Based on the first mode image, the incident parameters of the target beam are adjusted until the first mode image presents the corresponding first fundamental mode characteristics, thus completing the assembly and adjustment of the resonant cavity.

[0043] Fifthly, this application also provides a computer program product, wherein the resonant cavity has different levels of precision for beams of different polarization states, and the coupling rate between the beams of different polarization states and the resonant cavity increases as the precision decreases; it includes a computer program that, when executed by a processor, performs the following steps:

[0044] Based on the first precision corresponding to the target beam in the first polarization state, a reference beam in the second polarization state is obtained, and the reference beam is coupled into the resonant cavity to be assembled and adjusted; the target beam includes the beam used by the resonant cavity after assembly and adjustment, and the second precision corresponding to the reference beam is less than the first precision of the target beam;

[0045] A second mode image is acquired by coupling the reference beam with the resonant cavity; the second mode image is used to guide the adjustment of the alignment parameters of the resonant cavity until the second mode image presents the corresponding second fundamental mode characteristics.

[0046] After presenting the second fundamental mode feature, the reference beam is switched to the target beam to obtain a first mode image formed by the coupling of the target beam with the resonant cavity;

[0047] Based on the first mode image, the incident parameters of the target beam are adjusted until the first mode image presents the corresponding first fundamental mode characteristics, thus completing the assembly and adjustment of the resonant cavity.

[0048] The aforementioned resonant cavity assembly and adjustment method, apparatus, optical system for gas detection, computer-readable storage medium, and computer program product based on mode reference acquire a reference beam of a second polarization state based on a first precision corresponding to a target beam of a first polarization state, and couple the reference beam into the resonant cavity to be assembled and adjusted; the target beam includes the beam used by the resonant cavity after assembly and adjustment, and the second precision corresponding to the reference beam is less than the first precision of the target beam; a second mode image formed by the coupling of the reference beam and the resonant cavity is acquired; the second mode image is used to guide the adjustment of the alignment parameters of the resonant cavity until the second mode image presents the corresponding second fundamental mode characteristics; after presenting the second fundamental mode characteristics, the reference beam is switched to the target beam, and a first mode image formed by the coupling of the target beam and the resonant cavity is acquired; based on the first mode image, the incident parameters of the target beam are adjusted until the first mode image presents the corresponding first fundamental mode characteristics, thus completing the assembly and adjustment of the resonant cavity. In this application, a low-precision polarized light, which is easy to couple and has a strong mode signal, is used as a reference beam. The initial precise alignment of the resonant cavity is achieved based on the visualized first mode image, rather than the traditional single signal intensity. This solves the technical problems of traditional methods, such as the inability to determine the coupling state due to weak signals and the tendency to misidentify higher-order modes as the fundamental mode. Furthermore, after the resonant cavity is initially precisely aligned, the system switches to a high-precision target beam. This cleverly utilizes the established precise physical reference, avoiding the difficulty of initial alignment from scratch for high-precision modes due to extremely low coupling efficiency. This overcomes the shortcomings of low coupling efficiency, weak output signal, and difficulty in mode monitoring associated with high-precision polarized light and the resonant cavity, achieving highly efficient assembly and adjustment of the high-precision polarized resonant cavity. Attached Figure Description

[0049] To more clearly illustrate the technical solutions in the embodiments of this application or related technologies, the drawings used in the description of the embodiments of this application or related technologies will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0050] Figure 1 A system environment diagram for applying a mode reference-based resonant cavity assembly and tuning method in one embodiment;

[0051] Figure 2 This is a schematic flowchart of a mode-reference-based resonant cavity assembly and tuning method in one embodiment;

[0052] Figure 3a This is a fundamental mode spot pattern of a reference beam in one embodiment;

[0053] Figure 3b This is a fundamental mode spot pattern of the target beam in one embodiment;

[0054] Figure 3c This is a higher-order mode spot pattern of the reference beam in one embodiment;

[0055] Figure 3d This is an example of an anorectal spot pattern of the target beam in one embodiment;

[0056] Figure 4 This is a schematic diagram of the ring-down signal under different polarization modes in one embodiment;

[0057] Figure 5 This is a flowchart illustrating a mode-reference-based resonant cavity assembly and tuning method in another embodiment.

[0058] Figure 6 This is a structural block diagram of a mode-reference-based resonant cavity assembly and adjustment device in one embodiment;

[0059] Figure 7 This is an internal structural diagram of an optical system for gas detection in one embodiment. Detailed Implementation

[0060] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of this application.

[0061] It should be noted that the terms "first," "second," etc., used in this application can be used to describe various objects, but these elements are not limited by these terms. These terms are only used to distinguish the first element from the second element. The terms "comprising" and "having," and any variations thereof, used in this application, are intended to cover non-exclusive inclusion. The term "multiple" used in this application refers to two or more. The term "and / or" used in this application refers to one of the embodiments, or any combination of multiple embodiments.

[0062] This application provides a mode-reference-based resonant cavity assembly and tuning method, which can be applied to... Figure 1 The illustrated optical system for gas detection. In one embodiment, the system may include an infrared indicator light module, a laser light source 2, an acousto-optic modulator 3, a mode matching module, a polarization state tuning module, a resonant cavity as the object to be tuned, a gas path module, a mode monitoring module, a signal acquisition module, and a computer 10 as a control and processing center.

[0063] In an exemplary embodiment, a beam from a light source laser 2 (e.g., a wavelength-tunable distributed feedback (DFB) laser) first passes through an acousto-optic modulator 3, which acts as a high-speed optical switch. The beam then enters a mode matching module, which shapes and precisely points the spatial parameters of the laser beam. Specifically, the mode matching module may include a collimator 4.1 for converting the laser beam output from the fiber into spatial light, third and fourth mirrors 4.2 and 4.3 for precisely adjusting the incident position and angle of the laser beam, and a matching lens 4.4 for adjusting the size and position of the laser beam waist. To periodically form resonance, the module may also include a signal generator 4.5, which generates a scanning signal that drives a piezoelectric ceramic plate 4.7 coupled to a cavity mirror via a high-voltage driver 4.6 to perform a high-frequency scanning of the resonant cavity length.

[0064] The beam, shaped by the mode matching module, enters the polarization tuning module. This module can control the angles of the λ / 2 waveplate 5.1 (λ being the wavelength of light) and the linear polarizer 5.2 to set the laser beam as a reference beam with lower second precision or a target beam with higher first precision, depending on the needs of the assembly and tuning steps.

[0065] The polarization-selected beam is ultimately coupled into the resonant cavity. The resonant cavity is the core component to be assembled and tuned, and it may include the cavity body 6.4 and multiple high-reflectivity cavity mirrors forming the annular resonant optical path, such as a planar input mirror 6.1, a planar output mirror 6.2, and a planar-concave mirror 6.3. Simultaneously, the resonant cavity can also be connected to a gas path module for introducing the gas sample to be tested. A gas pump (not shown in the figure) and an inlet 7.1 and an outlet 7.2 are used to update the gas flow within the resonant cavity.

[0066] The beam transmitted from the resonant cavity is guided to two different detection modules depending on the operating stage. During the setup and adjustment stage, a pinhole aperture 8.1 filters out higher-order modes with larger beam diameters, and a retroreflector 8.2 is placed in the optical path to guide the transmitted beam to the mode monitoring module. An infrared camera 8.3 within this module captures real-time images of the two-dimensional spatial pattern of the transmitted beam and transmits the image data to a computer 10 for analysis and display. After setup and adjustment, the retroreflector 8.2 is removed from the optical path, and the transmitted beam directly enters the signal acquisition module. A focusing lens 9.1 in this module converges the beam to a detector 9.2, which converts the optical signal into an electrical signal and transmits it to a circuit control board 9.3 to trigger the acquisition of ring-down events. Additionally, optionally, during the initial setup and adjustment stage, an infrared indicator light module can be used to provide a coaxial reference for the entire optical path.

[0067] In one exemplary embodiment, such as Figure 2As shown, a method for assembling and adjusting a resonant cavity based on a mode reference is provided, which can be applied to... Figure 1 The following description uses an optical system for gas detection as an example, including the following steps S202 to S208. Wherein:

[0068] Step S202: Based on the first fineness corresponding to the target beam in the first polarization state, obtain the reference beam in the second polarization state, and couple the reference beam into the resonant cavity to be assembled and adjusted; the target beam includes the beam used by the resonant cavity after assembly and adjustment, and the second fineness corresponding to the reference beam is less than the first fineness of the target beam.

[0069] Specifically, based on the characteristics of the high-precision target beam (e.g., S-polarized light, corresponding to the first precision) ultimately used for measurement, the beam from the light source laser 2 is set as a reference beam (e.g., P-polarized light) with a second polarization state by adjusting the polarization state tuning module. In some embodiments, the mounting base of the λ / 2 waveplate 5.1 can be rotated to maximize the P-polarization component in the incident light, and the mounting base of the linear polarizer 5.2 can be rotated to make the fast axis of the linear polarizer 5.2 and the optical platform horizontal, thereby eliminating the S-polarization component in the incident light as much as possible. The second precision corresponding to the reference beam is lower than the first precision of the target beam. This characteristic ensures that the reference beam has a high coupling efficiency with the resonant cavity, thereby generating a strong transmitted light signal that is easy to monitor by subsequent modules. Specifically, the precision of the resonant cavity is mainly determined by the reflectivity of the cavity mirrors, while the efficient coupling of the beam into the resonant cavity is directly related to the transmittance of the input cavity mirrors. For an ideal low-loss cavity mirror, higher reflectivity corresponds to lower transmittance. Therefore, when the resonant cavity is in a lower second fineness state, it means that its cavity mirror has a relatively low second reflectivity, which also means that it has a relatively high transmittance. In the initial stage of mode matching, higher transmittance allows a larger portion of the incident reference beam energy to penetrate the input cavity mirror and enter the resonant cavity. This enables the establishment of a sufficiently strong intracavity optical field even under non-ideal resonance conditions, generating a transmitted light signal with sufficient brightness that is easily observed by the mode monitoring module. Thus, high coupling efficiency and high observation efficiency are ensured during the assembly and adjustment process.

[0070] Step S204: Obtain a second mode image of the resonant cavity based on mode reference, formed by coupling the reference beam with the resonant cavity; the second mode image is used to guide the adjustment of the alignment parameters of the resonant cavity until the second mode image presents the corresponding second fundamental mode characteristics.

[0071] The fundamental mode characteristic describes the ideal optical field distribution within the resonant cavity. The presence of the fundamental mode indicates a good match between the laser and the resonant cavity, achieving a resonant state that propagates along the optical axis. It can be represented as a bright spot with a single, centrally symmetrical intensity peak, whose intensity smoothly decreases from the central maximum value outwards, and there are no nodes or dark rings with zero intensity within the central bright spot. In a specific embodiment, for a standard resonant cavity composed of spherical mirrors, the fundamental mode characteristic appears as a perfectly circular light spot on the mode monitoring module, and its intensity distribution conforms to a Gaussian function, such as... Figure 3a and Figure 3b As shown. In some other resonant cavities with specific symmetries (such as resonant cavities containing cylindrical mirrors), this fundamental mode characteristic can also manifest as an elliptical spot with concentrated energy.

[0072] Specifically, after the reference beam enters the resonant cavity, reference alignment is then performed, guiding the transmitted light output from the resonant cavity to the mode monitoring module to acquire a second mode image formed by the reference beam within the cavity. In one embodiment, this mode image is a spatial distribution pattern of the light spot captured in real time by an infrared camera 8.3. Based on the shape of this real-time monitored second mode image, the system adjusts the alignment parameters of the resonant cavity. These alignment parameters can be physical parameters of the resonant cavity, such as the position and angle of the cavity mirrors (6.1, 6.2, 6.3) constituting the resonant cavity. This adjustment process uses the mode image to extract complex higher-order mode features, such as... Figure 3c As shown, the evolution progresses from simple fundamental mode features to guiding features, until the second mode image presents a clear and stable circular light spot, which corresponds to the second fundamental mode feature, such as... Figure 3a As shown, this indicates that the laser has reached a stable resonance state through repeated cycles within the cavity, meaning that the physical structure of the resonant cavity itself has reached alignment.

[0073] Step S206: After presenting the second fundamental mode features, the reference beam is switched to the target beam to obtain the first mode image formed after the target beam is coupled with the resonant cavity.

[0074] After the physical structure of the resonant cavity has reached alignment and exhibits the characteristics of the second fundamental mode, the physical parameters of the relevant cavity mirrors are fixed. Next, the control system switches the polarization state of the beam from the second polarization state of the reference beam to the first polarization state of the target beam by adjusting the polarization state tuning module. The target beam is the beam ultimately used for measurement after the resonant cavity is assembled and tuned. Its first level of precision is higher than the second level of precision of the reference beam, and it is extremely sensitive to the incident conditions. Specifically, the incident light is tuned to a high-precision S-polarized light. The mounting base of the λ / 2 waveplate 5.1 is rotated to maximize the S-polarization component in the incident light. The mounting base of the linear polarizer 5.2 is rotated so that the fast axis of the linear polarizer 5.2 is perpendicular to the optical platform, minimizing the P-polarization component in the incident light. After switching, the first mode image formed by the coupling of the target beam and the resonant cavity is acquired again through the mode monitoring module. In one embodiment, this mode image is a spatial distribution pattern of the light spot captured in real time by the infrared camera 8.3.

[0075] Step S208: Based on the first mode image, adjust the incident parameters of the target beam until the first mode image presents the corresponding first fundamental mode characteristics, thus completing the assembly and adjustment of the resonant cavity.

[0076] Specifically, due to the high precision characteristics of the target beam, even minor optical path disturbances caused by polarization switching may result in the first mode image not being an ideal fundamental mode. Therefore, after acquiring the first mode image of the target beam, a final fine-tuning is performed. Based on this first mode image, the incident parameters of the target beam are adjusted while keeping the physical parameters of the resonant cavity unchanged. Here, the incident parameters refer to the spatial parameters of the beam before entering the resonant cavity. Optionally, the incident position, incident angle, or beam waist parameters of the beam can be changed by adjusting the mirrors (4.2, 4.3) and matching lens 4.4 in the mode matching module. This fine-tuning continues until the first mode image changes from a potentially non-resonant spot, such as... Figure 3d As shown, or higher-order mode light spots, exhibit a clear and stable first fundamental mode characteristic, such as Figure 3b As shown. At this point, the high-precision target beam also achieves optimal coupling with the resonant cavity, and the entire resonant cavity assembly and adjustment process is completed.

[0077] In this embodiment, a low-precision polarized light, which is easy to couple and has a strong mode signal, is used as the reference beam. The initial precise alignment of the resonant cavity is achieved based on its visualized first mode image, rather than the traditional single signal intensity. This solves the technical problems of traditional methods, such as the inability to determine the coupling state due to weak signals and the tendency to misidentify higher-order modes as the fundamental mode. Based on this, after the resonant cavity is initially precisely aligned, the system switches to a high-precision target beam. This cleverly utilizes the established precise physical reference, avoiding the difficulty of initial alignment from scratch for high-precision modes due to extremely low coupling efficiency. This overcomes the shortcomings of low coupling efficiency, weak output signal, and difficulty in mode monitoring associated with high-precision polarized light and the resonant cavity, achieving high-efficiency assembly and adjustment of the high-precision polarized resonant cavity.

[0078] In an exemplary embodiment, before obtaining a reference beam with a second polarization state based on a first level of precision corresponding to the target beam with a first polarization state, the method further includes:

[0079] Acquire the beam of the indicator light source and use the beam of the indicator light source to pre-align the geometric center of the resonant cavity; combine the reference beam and the beam of the indicator light source coaxially so that the reference beam propagates along the pre-aligned path.

[0080] The indicator light beam can be an auxiliary beam that is independent of the main measurement light source, has good collimation and high visibility (or can be detected by the camera), and is used to establish a physical, visual alignment reference for the entire optical system before the assembly begins.

[0081] Specifically, the system activates the helium-neon laser 1.1 in the infrared indicator light module to obtain the beam of the indicator light source. By adjusting the angles of the first reflector 1.2 and the second reflector 1.3, the path of the indicator beam is made parallel to the optical platform and at a preset optical path height. Subsequently, the resonant cavity 6.4 is fixed on the five-dimensional adjustment frame and placed in the optical path, and its position is adjusted until the indicator beam can accurately pass through the center of the positioning holes reserved for the input and output mirrors on the cavity. After the cavity mirrors (6.1, 6.2, 6.3) are installed, multiple indicator light spots formed by multiple reflections are detected at the output end, and the angles of each cavity mirror are coarsely adjusted until the relevant light spots coincide with a single point. At this point, the pre-alignment of the geometric center of the resonant cavity is completed. After the pre-alignment is completed, the light source laser 2 is activated to generate a reference beam, and the reflectors (4.2, 4.3) in the mode matching module are adjusted so that the propagation paths of the reference beam and the indicator beam are completely coincident, thereby achieving coaxial beam combining, allowing the reference beam to accurately travel into the resonant cavity along the established pre-aligned path.

[0082] In this embodiment, by first establishing a precise physical reference axis using a clearly visible indicator light source, a clear path guide is provided for the introduction of subsequent beams, thereby enabling coaxial beam combining. This ensures that the reference beam can begin subsequent precise alignment on a good foundation that has already undergone preliminary optimization, laying a solid foundation for the high efficiency and high precision of the entire assembly and adjustment method.

[0083] In one exemplary embodiment, acquiring a second-mode image formed by the coupling of a reference beam and a resonant cavity includes:

[0084] A periodic scanning signal is acquired, and the cavity length of the resonant cavity is controlled to change periodically according to the scanning signal so that the reference beam is coupled in the resonant cavity to form resonance; during the periodic change of the cavity length of the resonant cavity, multiple second-mode images of the reference beam at resonance are acquired.

[0085] In this context, a periodic scanning signal refers to an electrical signal generated by a signal source that has a fixed repetition frequency and waveform (such as a triangular wave or a sawtooth wave). This signal is not used to carry information, but rather serves as a driving command to control a actuator to perform continuous reciprocating periodic motion.

[0086] Specifically, a periodic scanning signal is acquired and applied to a cavity length actuator coupled to the resonant cavity. The cavity length actuator, according to the command of the scanning signal, continuously and periodically performs minute changes or scans of the cavity length. Because the cavity length is continuously scanned, the resonance condition between the reference beam and the resonant cavity is periodically and instantaneously satisfied, thus coupling and forming resonance. During this periodic change in cavity length, the infrared camera 8.3 in the mode monitoring module synchronously acquires images, thereby capturing the second mode image presented by the reference beam at the moment of resonance in each scanning cycle.

[0087] In this embodiment, by periodically scanning the cavity length, a static resonant point is transformed into a stable and repetitive resonant event, which can be stably presented on the monitoring screen in the form of flashing, greatly enhancing the monitorability and stability of the pattern.

[0088] In one exemplary embodiment, the resonant cavity includes multiple cavity mirrors, one of which is connected to a driver of a piezoelectric ceramic plate; the cavity length of the resonant cavity is periodically varied according to a scanning signal to couple a reference beam within the resonant cavity to form resonance, including:

[0089] The scanning signal is input to the driver of the piezoelectric ceramic sheet. The driver of the piezoelectric ceramic sheet drives the piezoelectric ceramic sheet to perform telescopic movement according to the scanning signal, so that when the cavity length of the resonant cavity and the wavelength of the reference beam meet the preset phase matching condition, the reference beam couples in the resonant cavity to form resonance.

[0090] Specifically, one of the multiple cavity mirrors in the resonant cavity (e.g., plano-concave mirror 6.3) is physically coupled to a piezoelectric ceramic plate 4.7, for example, by adhesive bonding or mechanical fixation, so that the expansion and contraction of the piezoelectric ceramic plate 4.7 can directly drive the cavity mirror to move. A periodic scanning signal is generated by a signal generator 4.5 and sent as an input signal to a piezoelectric ceramic plate driver, such as a high-voltage driver 4.6. The high-voltage driver 4.6 amplifies the received low-voltage scanning signal into a high-voltage drive signal and applies it to the piezoelectric ceramic plate 4.7. Under the action of this high-voltage drive signal, the piezoelectric ceramic plate 4.7 undergoes precise expansion and contraction movements synchronized with the scanning signal waveform, thereby driving the coupled cavity mirror to reciprocate and directly change the optical length of the resonant cavity to achieve periodic scanning of the cavity length.

[0091] In one embodiment, prior to periodic scanning, the pattern matching module converts the laser output from the fiber into spatial light via collimator 4.1. The spatial beam then passes through adjustable third and fourth reflectors 4.2 and 4.3. Changing the angle of the reflectors allows for precise adjustment of the incident position and angle of the laser beam onto the resonant cavity. The beam then passes through a matching lens 4.4, which can be mounted within a telescopic sleeve. Rotating the sleeve changes its position, enabling size and positional matching between the laser beam waist and the intrinsic beam waist of the resonant cavity, followed by periodic scanning to achieve resonance.

[0092] In this embodiment, piezoelectric ceramic plates are used to achieve high-precision and high-speed scanning, which not only ensures that the resonance conditions can be stably and reliably swept periodically, providing a clear and stable dynamic image for mode observation, but also makes the range and frequency of cavity length scanning precisely adjustable, enhancing the flexibility and controllability of the entire assembly and adjustment system.

[0093] In an exemplary embodiment, based on a first mode image, the incident parameters of the target beam are adjusted until the first mode image exhibits the corresponding first fundamental mode characteristics, thus completing the assembly and adjustment of the resonant cavity, including:

[0094] Identify whether the first-mode image after the target beam is coupled with the resonant cavity shows any abnormalities; abnormalities include higher-order mode spots and non-resonant spots; if abnormalities are found, adjust the incident parameters related to the resonant cavity until the first-mode image presents the corresponding first fundamental mode characteristics.

[0095] Among them, higher-order mode light spots are a specific manifestation of display anomalies, and can refer to a type of stable resonance pattern with complex spatial distribution and non-concentrated energy, such as... Figure 3c As shown, its appearance indicates that the optical path is closed but there is a spatial mismatch. An anorexic spot is another specific manifestation of anomalies, and can refer to a weak or diffuse spot of light, such as... Figure 3d As shown, its appearance indicates that the coupling efficiency between the laser and the resonant cavity is extremely low, and an effective resonant state has not been achieved.

[0096] For example, the pattern monitoring module can acquire and identify whether the first pattern image formed after the target beam is coupled with the resonant cavity displays anomalies. For instance, a slight optical path shift due to polarization switching may lead to lower resonant coupling efficiency. In this case, the infrared camera 8.3 may capture a weak, diffuse spot, which can be identified as a non-resonant spot in the display anomaly. Figure 3d As shown.

[0097] If the first mode image is identified as displaying anomalies, the incident parameters of the resonant cavity need to be adjusted. Specifically, while keeping the physical position and angle of the cavity mirrors unchanged, the incident position, angle, and beam waist parameters of the target beam are changed by adjusting the mirrors 4.2 and 4.3 and the matching lens 4.4 in the mode matching module. This adjustment process continues until the first mode image changes from a displaying abnormal state to a clear and stable first fundamental mode feature, such as... Figure 3b As shown.

[0098] In this embodiment, by clearly defining two typical states of display abnormality, the operator or control system can accurately determine the system state after switching to high precision mode. At the same time, the adjustment object at this stage is limited to the incident parameters, thereby avoiding repeated adjustment of the alignment parameters that have been calibrated in the previous steps, ensuring high efficiency and high success rate of the entire assembly and adjustment process.

[0099] In an exemplary embodiment, after the first mode image presents the corresponding first fundamental mode feature, the method further includes:

[0100] The output signal after the target beam is coupled with the resonant cavity is acquired; if the value of the output signal is greater than the preset beam truncation threshold, the target beam is truncated, and the output signal after the target beam is truncated is acquired; based on the output signal after the target beam is truncated, the decay time of the target beam is determined to determine that the current resonant cavity assembly is complete.

[0101] In one embodiment, when the first mode image of the target beam exhibits the corresponding first fundamental mode characteristics, indicating that geometric alignment and mode matching are complete, a final functional verification of the assembly result is performed. Specifically, the output optical path of the resonant cavity is switched from the mode monitoring module to the signal acquisition module, for example, by retracting the folding mirror 8.2. At this time, the transmitted light of the target beam is converged to the photosensitive surface of the detector 9.2 via the focusing lens 9.1. The detector 9.2 converts the light intensity signal into an electrical signal, i.e., an output signal, and transmits it to the circuit control board 9.3. The circuit control board 9.3 compares the real-time value of the output signal with a preset beam truncation threshold. If the value of the output signal is greater than the threshold, it indicates that the resonant intensity is high enough, and the circuit control board 9.3 sends a command to truncate the target beam, for example, by driving the acousto-optic modulator 3 to quickly shut off the incident laser. At the instant the beam is truncated, the computer 10 simultaneously begins to acquire and record the signal of the light intensity decaying exponentially over time as measured by the detector 9.2. Finally, the computer 10 performs exponential fitting on the acquired decay signal to determine the decay time of the target beam, such as... Figure 4 As shown in curve b. Exemplarily, the ringing time of the reference beam can be further determined through the above steps, such as... Figure 4 The curve a is shown in the figure.

[0102] In this embodiment, by setting a beam cutoff threshold, it is possible to objectively determine whether the resonance intensity has met the functional requirements, eliminating the subjectivity of human observation. Successfully triggering the cutoff and measuring a stable, long-term decay time is the final and most reliable verification of the effectiveness of the entire assembly and adjustment work.

[0103] In an exemplary embodiment, the second level of fineness and the first level of fineness are determined by the following steps:

[0104] A first level of precision is determined based on the first reflectivity of the target beam in the first polarization state; a second level of precision is determined based on the second reflectivity of the cavity mirror of the resonant cavity for the reference beam in the second polarization state; the first reflectivity is higher than the second reflectivity.

[0105] Among them, reflectivity refers to the ratio of the light power reflected from the cavity mirror surface to the total incident light power. It is a dimensionless physical quantity between 0 and 1, which characterizes the strength of the cavity mirror's reflectivity. Fineness is used to quantitatively describe the resonant cavity's ability to store light energy and its spectral selectivity. Fineness can be determined by formula (1).

[0106]

[0107] in, Represents the fineness of the resonant cavity. The power reflectivity of the cavity mirrors representing the resonant cavity.

[0108] Specifically, the target beam in the first polarization state can be S-polarized light, and the cavity mirror has a high first reflectivity for S-polarized light, for example, the first reflectivity can be greater than 99.995%. According to the fineness calculation formula (1), it can be known that this high reflectivity corresponds to a high first fineness. At the same time, the reference beam in the second polarization state can be P-polarized light, and the cavity mirror has a relatively low second reflectivity for P-polarized light, for example, the second reflectivity is about 99.9%. According to the fineness calculation formula (1), it can be known that this reflectivity corresponds to a relatively low second fineness.

[0109] In this embodiment, the above steps enable the use of cavity mirrors with different reflectivities for different polarization states, allowing the same resonant cavity to exhibit two distinctly different precision states, high and low, depending on the polarization state of the incident light. This is the physical basis for realizing the assembly and adjustment method of this application.

[0110] To enable those skilled in the art to better understand the above steps, the following example illustrates the embodiments of this application, but it should be understood that the embodiments of this application are not limited thereto.

[0111] In one exemplary embodiment, laser absorption spectroscopy is a commonly used method in the field of gas monitoring. Cavity ring-down absorption spectroscopy (CRDS) is one of the most representative laser absorption spectroscopy techniques, with advantages such as high sensitivity, long effective optical path, and immunity to light source intensity interference.

[0112] The resonant cavity is one of the most critical structures in a CRDS system. The system's long optical path length is achieved through the ultra-high reflectivity of the cavity mirrors; the higher the mirror reflectivity, the longer the effective optical path and the higher the sensitivity. Cavity mirrors typically have different reflectivities for incident lasers with different polarization states. In resonant cavities where standing waves cannot be formed, phase delays occur between different polarization states, ultimately leading to large fluctuations in ring-down time and reducing the system's accuracy and measurement precision. Therefore, for these polarization resonant cavities, it is essential to ensure the linear polarization and polarization state stability of the incident light. Typically, low-precision polarized light is filtered out, allowing high-precision polarized light to enter the resonant cavity for gas concentration measurement.

[0113] Mode matching is also one of the key factors affecting sensitivity. When laser light is incident on a resonant cavity, it will excite the cavity's intrinsic modes. Higher-order modes have larger spot diameters and faster loss, while the fundamental mode has the smallest diameter among the correlated modes, with concentrated energy, low loss, and longer decay time. Therefore, whether fundamental mode matching can be achieved is the main means of measuring the resonant cavity's assembly and tuning effect.

[0114] Most existing resonant cavity assembly and adjustment methods determine whether fundamental mode matching has been achieved based on the intensity of mode signals. The fundamental mode signal intensity is higher than other modes; during assembly and adjustment, the detector is considered to have the fundamental mode if it detects a signal with a significantly higher intensity than other modes. This method has limitations. Some lower-order modes have signal intensities weaker than the fundamental mode but higher than other higher-order modes. If fundamental mode matching has not been achieved, the presence of these modes may be misinterpreted as the fundamental mode. For high-precision polarization resonant cavities, due to the low coupling efficiency between the laser and the resonant cavity, the detector struggles to detect higher-order modes before fundamental mode resonance is achieved, making it impossible to determine the coupling state between the laser and the resonant cavity. This can be addressed by... Figure 5 The method and steps shown solve the above problem, specifically including:

[0115] S1, turn on the indicator light module, adjust the infrared indicator light level to be the same as the reference infrared indicator light on the optical platform, and coarsely adjust the position of the resonant cavity and the cavity mirror so that their geometric centers are on the same horizontal plane.

[0116] Before precision assembly begins, a separate indicator light source is first turned on, such as the helium-neon laser 1.1 in the infrared indicator light module, whose output beam serves as the indicator light. By adjusting the reflectors (1.2, 1.3), the path of this indicator beam is precisely set at the preset optical path height and made parallel to the optical platform. Subsequently, referring to this indicator beam, the geometric positions of the cavity 6.4 and the cavity mirrors (6.1, 6.2, 6.3) of the resonant cavity to be assembled are coarsely adjusted so that their geometric centers are approximately on the same horizontal plane, thus establishing a preliminary coaxial relationship.

[0117] S2, turn on the light source laser, operate the mode matching module, combine the light source and the indicator light, couple the light source into resonance, and turn off the indicator light.

[0118] After initial geometric alignment, the main light source, namely laser source 2, is turned on. The mirrors (4.2, 4.3) in the operation mode matching module coaxially combine the beam from laser source 2 with the propagation path of the indicator beam, ensuring that the main beam can propagate along the established reference path and couple into the resonant cavity. After beam combining is complete, the indicator beam module can be turned off.

[0119] S3, the polarization adjustment module outputs low-precision polarized light and couples it into the resonant cavity to erect the folding mirror. The transmitted light from the resonant cavity enters the mode monitoring module. The computer software analyzes the mode captured by the infrared camera and finely adjusts the position of the resonant cavity and the cavity mirror according to the mode spot until the fundamental mode appears.

[0120] The polarization tuning module is operated to set the beam as a reference beam with a lower second fineness (e.g., P-polarized light). Then, the transmitted light from the resonant cavity is guided to the infrared camera 8.3 in the mode monitoring module to acquire a second-mode image formed within the cavity by the reference beam. To ensure stable observation of the resonant mode, the cavity length can be periodically scanned using devices such as a signal generator 4.5 and a piezoelectric ceramic plate 4.7, allowing resonance to form periodically. The operator finely adjusts the physical alignment parameters of the resonant cavity (mainly the position and angle of the cavity mirror) based on the shape of the second-mode image displayed on the camera screen until the second-mode image presents a clear and stable second fundamental mode characteristic (e.g., ...). Figure 3a (As shown).

[0121] S4, the polarization adjustment module adjusts the output light to high-precision polarized light, and observes the fundamental mode of the high-precision polarized light through an infrared camera. If there is no fundamental mode, the mode matching module is operated again to fine-tune the position and angle of the incident light until the fundamental mode appears.

[0122] After the physical alignment of the resonant cavity is completed, its physical parameters are fixed, and the polarization state tuning module is operated to switch the polarization state of the beam to a target beam with higher first-order precision (e.g., S-polarized light). After switching, the first-mode image of the target beam is acquired again via the infrared camera 8.3. If an image display abnormality is detected at this time (e.g., appearing as a non-resonant spot, such as...), Figure 3d As shown), while keeping the cavity mirror position unchanged, the incident parameters of the target beam are fine-tuned. Further, in the reference alignment step S3, the physical structure of the resonant cavity itself has been precisely calibrated by the reference beam to a stable state capable of supporting fundamental mode resonance. Using the polarization state switching operation in step S3 would introduce beam pointing or position offsets that deviate from the high-precision resonant cavity due to extremely small mechanical tolerances or misalignment of the optical components. Therefore, by keeping the already aligned resonant cavity stationary and only performing compensatory fine-tuning on the incident beam itself, the assembly and adjustment can be completed with high-precision polarization. Specifically, by operating the mode matching module again, the incident position and angle of the beam are changed until the first mode image presents a clear and stable first fundamental mode feature (such as...). Figure 3b (As shown).

[0123] S5, retract the folding mirror, the transmitted light from the resonant cavity enters the signal acquisition module, the detector transmits the signal to the circuit control board, the circuit control board compares the signal with the threshold, if it exceeds the threshold, the acousto-optic modulator chops it, the computer acquires the decaying signal, and the resonant cavity assembly and adjustment are completed.

[0124] After the target beam exhibits the corresponding first fundamental mode characteristics, a verification step is performed to finally confirm the assembly and adjustment effect. The reflecting mirror 8.2 in the mode monitoring module is retracted, and the transmitted light from the resonant cavity is guided to the signal acquisition module. The detector 9.2 and circuit control board 9.3 in this module acquire the output signal and determine whether its intensity is greater than a preset beam truncation threshold. If it is greater than the threshold, the acousto-optic modulator 3 is triggered to truncate the target beam, and the computer 10 acquires the truncated ringing signal of the beam. The ability to stably acquire a high-quality ringing signal confirms that the current resonant cavity assembly and adjustment is complete.

[0125] In this embodiment, through the above steps, the difficult physical alignment of the resonant cavity is completed using a low-precision reference beam with a clear signal. Based on this solid foundation, a simple incident fine adjustment is performed on the high-precision target beam, thereby effectively overcoming the problem of weak signal and difficulty in mode judgment when directly aligning with a high-precision cavity in the prior art, and achieving efficient and accurate assembly and adjustment.

[0126] It should be understood that although the steps in the flowcharts of the above embodiments are shown sequentially according to the arrows, these steps are not necessarily executed in the order indicated by the arrows. Unless explicitly stated herein, there is no strict order restriction on the execution of these steps, and they can be executed in other orders. Moreover, at least some steps in the flowcharts of the above embodiments may include multiple steps or multiple stages. These steps or stages are not necessarily completed at the same time, but can be executed at different times. The execution order of these steps or stages is not necessarily sequential, but can be performed alternately or in turn with other steps or at least some of the steps or stages in other steps. It is understood that the steps in different embodiments can be freely combined as needed, and all non-contradictory solutions formed by such combinations are within the scope of protection of this application.

[0127] Based on the same inventive concept, this application also provides a mode-reference-based resonant cavity assembly and tuning device for implementing the mode-reference-based resonant cavity assembly and tuning method described above. The solution provided by this device is similar to the implementation described in the above method. Therefore, the specific limitations of one or more mode-reference-based resonant cavity assembly and tuning device embodiments provided below can be found in the limitations of the mode-reference-based resonant cavity assembly and tuning method described above, and will not be repeated here.

[0128] In one exemplary embodiment, such as Figure 6As shown, a mode-reference-based resonant cavity assembly and adjustment device is provided. The resonant cavity has different levels of fineness corresponding to beams with different polarization states, and the coupling rate between the beams with different polarization states and the resonant cavity increases as the fineness decreases. The device includes: a reference beam coupling module 610, a reference beam resonance adjustment module 620, a target beam coupling module 630, and a target beam resonance adjustment module 640, wherein:

[0129] The reference beam coupling module 610 is used to obtain a reference beam in a second polarization state based on a first fineness corresponding to a target beam in a first polarization state, and to couple the reference beam into the resonant cavity to be assembled and adjusted; the target beam includes the beam used by the resonant cavity after assembly and adjustment, and the second fineness corresponding to the reference beam is less than the first fineness of the target beam;

[0130] The reference beam resonance adjustment module 620 is used to acquire a second mode image formed by the coupling of the reference beam and the resonant cavity; the second mode image is used to guide the adjustment of the alignment parameters of the resonant cavity until the second mode image presents the corresponding second fundamental mode characteristics.

[0131] The target beam coupling module 630 is used to switch the reference beam to the target beam after presenting the second fundamental mode feature, and to obtain a first mode image formed after the target beam is coupled with the resonant cavity;

[0132] The target beam resonance adjustment module 640 is used to adjust the incident parameters of the target beam based on the first mode image until the first mode image presents the corresponding first fundamental mode characteristics, thereby completing the assembly and adjustment of the resonant cavity.

[0133] In one embodiment, the reference beam coupling module 610 is further configured to acquire the beam of the indicator light source and pre-align the geometric center of the resonant cavity using the beam of the indicator light source; and to coaxially combine the reference beam with the beam of the indicator light source so that the reference beam propagates along the pre-aligned path.

[0134] In one embodiment, the target beam resonance adjustment module 640 is further configured to acquire a periodic scanning signal and control the cavity length of the resonant cavity to change periodically according to the scanning signal, so that the reference beam is coupled in the resonant cavity to form resonance; during the periodic change of the cavity length of the resonant cavity, multiple second mode images of the reference beam at resonance are acquired.

[0135] In one embodiment, the resonant cavity includes multiple cavity mirrors, one of which is connected to a piezoelectric ceramic plate driver; the target beam resonance adjustment module 640 is further configured to input the scanning signal to the piezoelectric ceramic plate driver, and the piezoelectric ceramic plate driver drives the piezoelectric ceramic plate to perform telescopic movement according to the scanning signal, so that when the cavity length of the resonant cavity and the wavelength of the reference beam meet a preset phase matching condition, the reference beam couples and forms resonance in the resonant cavity.

[0136] In one embodiment, the target beam resonance adjustment module 640 is further configured to identify whether the first mode image after the target beam is coupled with the resonant cavity displays an abnormality; the abnormality includes higher-order mode spots and non-resonant spots; in the case of an abnormality, the incident parameters related to the resonant cavity are adjusted until the first mode image presents the corresponding first fundamental mode feature.

[0137] In one embodiment, the target beam resonance adjustment module 640 is further configured to acquire the output signal after the target beam is coupled with the resonant cavity; if the value of the output signal is greater than a preset beam truncation threshold, the target beam is truncated, and the output signal after the target beam is truncated is acquired; based on the output signal after the target beam is truncated, the decay time of the target beam is determined to determine that the current resonant cavity is fully assembled.

[0138] In one embodiment, the target beam coupling module 630 is further configured to determine the first precision based on the first reflectivity of the target beam in the first polarization state; and to determine the second precision based on the second reflectivity of the cavity mirror of the resonant cavity for the reference beam in the second polarization state; wherein the first reflectivity is higher than the second reflectivity.

[0139] Each module in the aforementioned mode-reference-based resonant cavity assembly and tuning device can be implemented entirely or partially through software, hardware, or a combination thereof. These modules can be embedded in hardware within or independently of the processor in a computer device, or stored in software within the memory of a computer device, so that the processor can invoke and execute the corresponding operations of each module.

[0140] In one exemplary embodiment, an optical system for gas detection is provided. This optical system for gas detection can be a terminal, and its internal structure diagram can be as follows: Figure 7As shown, the optical system for gas detection includes a processor, memory, input / output interface, communication interface, display unit, and input device. The processor, memory, and input / output interface are connected via a system bus, and the communication interface, display unit, and input device are also connected to the system bus via the input / output interface. The processor provides computational and control capabilities. The memory includes a non-volatile storage medium and internal memory. The non-volatile storage medium stores the operating system and computer programs. The internal memory provides an environment for the operation of the operating system and computer programs in the non-volatile storage medium. The input / output interface allows the processor to exchange information with external devices. The communication interface allows for wired or wireless communication with external terminals; wireless communication can be achieved through Wi-Fi, mobile cellular networks, Near Field Communication (NFC), or other technologies. When executed by the processor, the computer program implements a mode-reference-based resonant cavity tuning method. The display unit of the optical system for gas detection forms a visually visible image and can be a display screen, projection device, or virtual reality imaging device. The display screen can be an LCD screen or an e-ink screen. The input device of the optical system for gas detection can be a touch layer covering the display screen, or a button, trackball, or touchpad set on the housing of the optical system for gas detection, or an external keyboard, touchpad, or mouse, etc.

[0141] Those skilled in the art will understand that Figure 7 The structure shown is merely a block diagram of a portion of the structure related to the present application and does not constitute a limitation on the optical system for gas detection applied thereto. A specific optical system for gas detection may include more or fewer components than those shown in the figure, or combine certain components, or have different component arrangements.

[0142] In one embodiment, an optical system for gas detection is provided, including a memory and a processor, wherein the memory stores a computer program, and the processor executes the computer program to implement the steps in the above-described method embodiments.

[0143] In one embodiment, a computer-readable storage medium is provided having a computer program stored thereon, which, when executed by a processor, implements the steps in the above method embodiments.

[0144] In one embodiment, a computer program product is provided, including a computer program that, when executed by a processor, implements the steps in the above method embodiments.

[0145] It should be noted that the user information (including but not limited to user device information, user personal information, etc.) and data (including but not limited to data used for analysis, data stored, data displayed, etc.) involved in this application are all information and data authorized by the user or fully authorized by all parties, and the collection, use and processing of the relevant data must comply with relevant regulations.

[0146] Those skilled in the art will understand that all or part of the processes in the methods of the above embodiments can be implemented by a computer program instructing related hardware. The computer program can be stored in a non-volatile computer-readable storage medium, and when executed, it can include the processes of the embodiments of the above methods. Any references to memory, databases, or other media used in the embodiments provided in this application can include at least one of non-volatile memory and volatile memory. Non-volatile memory can include read-only memory (ROM), magnetic tape, floppy disk, flash memory, optical memory, high-density embedded non-volatile memory, resistive random access memory (ReRAM), magnetic random access memory (MRAM), ferroelectric random access memory (FRAM), phase change memory (PCM), graphene memory, etc. Volatile memory can include random access memory (RAM) or external cache memory, etc. By way of illustration and not limitation, RAM can take many forms, such as Static Random Access Memory (SRAM) or Dynamic Random Access Memory (DRAM). The databases involved in the embodiments provided in this application may include at least one type of relational database and non-relational database. Non-relational databases may include, but are not limited to, blockchain-based distributed databases. The processors involved in the embodiments provided in this application may be general-purpose processors, central processing units, graphics processing units, digital signal processors, programmable logic devices, quantum computing-based data processing logic devices, artificial intelligence (AI) processors, etc., and are not limited to these.

[0147] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this application.

[0148] The embodiments described above are merely illustrative of several implementation methods of this application, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of this patent application. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this application should be determined by the appended claims.

Claims

1. A mode reference based resonator tuning method, characterized by, The resonant cavity corresponds to different fineness of light beams with different polarization states, and the coupling rate of light beams with different polarization states to the resonant cavity increases with the decrease of the fineness; the method comprises: Based on the first fineness corresponding to the target light beam with the first polarization state, a reference light beam with a second polarization state is obtained, and the reference light beam is coupled into the resonant cavity to be adjusted; the target light beam comprises a light beam used by the resonant cavity after adjustment is completed, and the second fineness corresponding to the reference light beam is smaller than the first fineness of the target light beam; the first fineness and the second fineness are determined by the following steps: the first fineness is determined according to the first reflectivity of the target light beam with the first polarization state; the second fineness is determined according to the second reflectivity of the reference light beam with the second polarization state to the cavity mirror of the resonant cavity; the first reflectivity is higher than the second reflectivity; A second mode image formed by coupling the reference light beam and the resonant cavity is obtained; the second mode image is used to guide the adjustment of the alignment parameters of the resonant cavity until the second mode image presents a corresponding second fundamental mode feature; After the second fundamental mode feature is presented, the reference light beam is switched to the target light beam, and a first mode image formed by coupling the target light beam and the resonant cavity is obtained; Based on the first mode image, the incident parameters of the target light beam are adjusted until the first mode image presents a corresponding first fundamental mode feature, and the adjustment of the resonant cavity is completed.

2. The method of claim 1, wherein, Before the second polarization state reference light beam is obtained based on the first fineness corresponding to the target light beam with the first polarization state, it further comprises: An optical beam of an indicating light source is obtained, and the geometric center of the resonant cavity is pre-aligned by using the optical beam of the indicating light source; The reference light beam is coaxially combined with the optical beam of the indicating light source, so that the reference light beam propagates along the pre-aligned path.

3. The method of claim 2, wherein, The second mode image formed by coupling the reference light beam and the resonant cavity comprises: A periodic scanning signal is obtained, and the cavity length of the resonant cavity is controlled to change periodically according to the scanning signal, so that the reference light beam is coupled to form resonance in the resonant cavity; During the process that the cavity length of the resonant cavity changes periodically, a plurality of second mode images of the reference light beam when resonating are obtained.

4. The method of claim 3, wherein, The resonant cavity comprises a plurality of cavity mirrors, one of the plurality of cavity mirrors is connected with a piezoelectric ceramic sheet driver; The cavity length of the resonant cavity is controlled to change periodically according to the scanning signal, so that the reference light beam is coupled to form resonance in the resonant cavity, comprising: The scanning signal is input to the piezoelectric ceramic sheet driver, and the piezoelectric ceramic sheet driver drives the piezoelectric ceramic sheet to perform extension and contraction motion according to the scanning signal, so that when the cavity length of the resonant cavity and the wavelength of the reference light beam satisfy the preset phase matching condition, the reference light beam is coupled to form resonance in the resonant cavity.

5. The method of claim 1, wherein, Based on the first mode image, the incident parameters of the target light beam are adjusted until the first mode image presents a corresponding first fundamental mode feature, and the adjustment of the resonant cavity is completed, comprising: identifying whether the first mode image of the target light beam coupled with the resonant cavity shows abnormality; the abnormality includes high-order mode light spot and non-resonant light spot; in the case of showing abnormality, adjusting the incident parameter related to the resonant cavity until the first mode image presents the corresponding first fundamental mode feature.

6. The method of claim 1, wherein, after the first mode image presents the corresponding first fundamental mode feature, further comprising: obtaining an output signal of the target light beam coupled with the resonant cavity; if the value of the output signal is greater than a preset light beam truncation threshold, truncating the target light beam, and obtaining an output signal of the target light beam after being truncated; determining the ring-down time of the target light beam according to the output signal of the target light beam after being truncated, to determine that the current resonant cavity is adjusted and completed.

7. A mode reference based resonator tuning device, characterized by, the resonant cavity corresponds to different fineness for light beams of different polarization states, and the coupling rate of light beams of different polarization states with the resonant cavity increases with the decrease of the fineness; the device comprises: a reference light beam coupling module, configured to obtain a reference light beam of a second polarization state based on a first fineness corresponding to a target light beam of a first polarization state, and couple the reference light beam into a resonant cavity to be adjusted; the target light beam includes a light beam used by the resonant cavity after being adjusted and completed, and a second fineness corresponding to the reference light beam is less than a first fineness of the target light beam; the first fineness and the second fineness are determined by the following steps: determining the first fineness according to a first reflectivity of the target light beam of the first polarization state; determining the second fineness according to a second reflectivity of the reference light beam of the second polarization state to the cavity mirror of the resonant cavity; the first reflectivity is higher than the second reflectivity; a reference light beam resonance adjustment module, configured to obtain a second mode image formed by coupling the reference light beam with the resonant cavity; the second mode image is used to guide the adjustment of the alignment parameter of the resonant cavity until the second mode image presents a corresponding second fundamental mode feature; a target light beam coupling module, configured to switch the reference light beam to the target light beam after presenting the second fundamental mode feature, and obtain a first mode image formed by coupling the target light beam with the resonant cavity; a target light beam resonance adjustment module, configured to adjust the incident parameter of the target light beam based on the first mode image until the first mode image presents a corresponding first fundamental mode feature, to complete the adjustment of the resonant cavity.

8. A computer-readable storage medium having stored thereon a computer program, characterized in that, The computer program is executed by the processor to realize the steps of the method of any one of claims 1 to 6.

9. A computer program product comprising a computer program, characterized in that, The computer program is executed by the processor to realize the steps of the method of any one of claims 1 to 6.

Images