Optical multi-pass cell system

Abstract

The utility model belongs to the field of optical multi-pass pools, and provides an optical multi-pass pool system, comprising: an optical multi-pass pool comprising an input end and an output end; the driving mechanism is used for driving the M sub-reflectors of the optical multi-pass cell to periodically move back and forth in the Z-axis direction in each data acquisition process of the gas absorption data detection process, and the Z-axis direction is parallel to the optical axis of the optical multi-pass cell; wherein M is larger than or equal to 1, and the detection process comprises the steps that under the condition that the optical multi-pass cell is filled with gas to be detected, a detection light beam is input from the input end, and after multiple times of reflection in the optical multi-pass cell, an interference light beam is formed and output from the output end. According to the embodiment of the invention, the gas absorption data with smooth optical noise can be obtained, so that the sensitivity of detecting the gas absorption data based on the optical multi-pass cell system can be improved.

Description

Technical Field

[0001] This application relates to the technical field of optical multipass cells, and particularly to an optical multipass cell system. Background Art

[0002] To improve the sensitivity of gas detectors, optical multipass cells with longer optical paths are generally required. However, the longer the optical path, the larger the volume of the optical multipass cell, and the optical path cannot be increased indefinitely to improve the sensitivity. Existing optical multipass cell technologies, such as Herriot cells, White cells, etc., cannot meet the requirements of the industrial field for gas detectors with high sensitivity and small volume. Summary of the Utility Model

[0003] In view of this, embodiments of this application provide an optical multipass cell system, a gas absorption data detection method, a terminal device, and a storage medium to solve the problem that existing optical multipass cell technologies cannot meet the requirements of the industrial field for gas detectors with high sensitivity and small volume.

[0004] The first aspect of the embodiments of this application provides an optical multipass cell system, including:

[0005] An optical multipass cell, including an input end and an output end; and

[0006] A driving mechanism for driving M sub - mirrors of the optical multipass cell to move periodically back and forth along the Z - axis direction during each data acquisition process in the detection process of gas absorption data, where the Z - axis direction is parallel to the optical axis of the optical multipass cell;

[0007] where M≥1, and the detection process is: when the gas to be detected is filled in the optical multipass cell, the detection beam is input from the input end, forms an interference beam after multiple reflections in the optical multipass cell, and is output from the output end. During the entire detection process, the wavelength of the detection beam varies within a preset wavelength range, and the wavelength of the detection beam is constant or varies within a preset wavelength modulation range during each data acquisition process.

[0008] The first aspect of the embodiments of this application, by providing an optical multipass cell system including an optical multipass cell and a driving mechanism, during each data acquisition process in the detection process of gas absorption data, based on the driving mechanism driving M (M≥1) sub - mirrors among all the sub - mirrors of the optical multipass cell to move periodically back and forth along the Z - axis direction parallel to the optical axis of the optical multipass cell, can obtain interference beams at different positions of the M sub - mirrors at the output end without significantly increasing the volume of the optical multipass cell system. Based on these interference beams, gas absorption data with smoothed optical noise can be obtained, thereby being able to improve the sensitivity when detecting gas absorption data based on the optical multipass cell system.

[0009] In one embodiment, the optical multipass cell further includes:

[0010] The input end, which is used for inputting a detection beam;

[0011] The output end, which is used for outputting an interference beam;

[0012] A main concave mirror; and

[0013] Two sub - mirrors, the sub - mirrors are concave mirrors, the reflecting surfaces of the main concave mirror and the sub - mirrors face each other and are spaced apart to form a reflection cavity, and the optical axis of the reflection cavity is perpendicular to the focal plane of the main concave mirror;

[0014] Wherein, the input end is arranged on the main concave mirror, and the output end is arranged on the main concave mirror or any one of the sub - mirrors.

[0015] In the embodiment of the present application, by providing an optical multipass cell including a main concave mirror and two sub - mirrors, during each data acquisition process in the detection process of gas absorption data, based on the driving mechanism driving at least one of the two sub - mirrors of the optical multipass cell to move periodically back and forth along the Z - axis direction parallel to the optical axis of the optical multipass cell, it is possible to obtain interference beams when the M sub - mirrors are at different positions at the output end without significantly increasing the volume of the optical multipass cell system. Based on these interference beams, gas absorption data with smoothed optical noise can be obtained, thereby improving the sensitivity when detecting gas absorption data based on the optical multipass cell system.

[0016] In one embodiment, the optical multipass cell includes:

[0017] The input end, which is used for inputting a detection beam;

[0018] The output end, which is used for outputting an interference beam;

[0019] A main concave mirror;

[0020] A main plane mirror, the reflecting surfaces of the main concave mirror and the main plane mirror face each other and are spaced apart to form a reflection cavity, and the optical axis of the reflection cavity is perpendicular to the focal plane of the main concave mirror; and

[0021] N sub - mirrors, the sub - mirrors are arranged on the main plane mirror, and the reflecting surfaces of the N sub - mirrors face the main concave mirror;

[0022] Wherein, N≥M, the input end is arranged on the main concave mirror or the main plane mirror, and the output end is arranged on the main concave mirror, the main plane mirror or any one of the sub - mirrors.

[0023] In an embodiment of the present application, an optical multipass cell including a main concave mirror, a main plane mirror, and N sub-mirrors is provided. During each data acquisition process in the detection process of gas absorption data, based on the driving mechanism, M of the N sub-mirrors of the optical multipass cell are driven to move periodically back and forth along the Z-axis direction parallel to the optical axis of the optical multipass cell. Without significantly increasing the volume of the optical multipass cell system, interference beams at different positions of the M sub-mirrors can be obtained at the output end. Based on these interference beams, gas absorption data with smoothed optical noise can be obtained, thereby improving the sensitivity when detecting gas absorption data based on the optical multipass cell system.

[0024] In one embodiment, N = 1, and the sub-mirror is a plane mirror with an area smaller than that of the main plane mirror;

[0025] The inclination angle between the normal of the sub-mirror and the normal of the main plane mirror is θ1 and the inclination angle θ1 is not zero;

[0026] The driving mechanism is used to drive the sub-mirror to move.

[0027] In one embodiment, N = 2, and the N sub-mirrors include a first sub-mirror and a second sub-mirror;

[0028] Both the first sub-mirror and the second sub-mirror are plane mirrors with an area smaller than that of the main plane mirror. The inclination angle between the normal of the first sub-mirror and the normal of the main plane mirror is θ1 and the inclination angle θ1 is not zero;

[0029] The normal of the second sub-mirror is parallel to the normal of the main plane mirror. The second sub-mirror and the first sub-mirror are symmetric about the origin and are separated. The origin is the intersection point of the optical axis on the focal plane;

[0030] The driving mechanism is used to drive the second sub-mirror to move.

[0031] In one embodiment, N = 2, and the N sub-mirrors include a first sub-mirror and a second sub-mirror;

[0032] Both the first sub-mirror and the second sub-mirror are plane mirrors with an area smaller than that of the main plane mirror. The inclination angle between the normal of the first sub-mirror and the normal of the main plane mirror is θ1 and the inclination angle θ1 is not zero;

[0033] The normal of the second sub-mirror is parallel to the normal of the main plane mirror. The second sub-mirror and the first sub-mirror are symmetric about the origin and are adjacent. The origin is the intersection point of the optical axis on the focal plane;

[0034] The driving mechanism is used to drive the first sub - mirror and the second sub - mirror to move simultaneously.

[0035] In one embodiment, N = 2, and the N sub - mirrors include a first sub - mirror and a second sub - mirror;

[0036] Both the first sub - mirror and the second sub - mirror are planar mirrors with areas smaller than that of the main planar mirror. The inclination angle between the normal of the first sub - mirror and the normal of the main planar mirror is θ1 and the inclination angle θ1 is not zero;

[0037] The inclination angle between the normal of the second sub - mirror and the normal of the main planar mirror is θ2 and the inclination angle θ2 is not zero. The second sub - mirror and the first sub - mirror are symmetric about the origin and are adjacent to each other. The origin is the intersection point of the optical axis on the focal plane;

[0038] The driving mechanism is used to drive the first sub - mirror and the second sub - mirror to move simultaneously.

[0039] In one embodiment, the optical multi - pass cell includes:

[0040] The input end, which is used to input the detection beam;

[0041] The output end, which is used to output the interference beam;

[0042] The main concave mirror, with a focal length of f, a radius of curvature of R and having aberration;

[0043] The main planar mirror, the distance from the reflecting surface of the main planar mirror to the optical center of the main concave mirror is L1=(1 + x1)f, - 1 < x1 < 1; and

[0044] The sub - mirror, which is a concave mirror with a focal length of f0, a radius of curvature of R0 and is arranged on the main planar mirror. The area of the positive projection of the reflecting surface of the sub - mirror on the reflecting surface of the main planar mirror is smaller than the area of the reflecting surface of the main planar mirror. The distance from the optical center of the sub - mirror to the optical center of the main concave mirror is L2=(1 + x2)f, R0 = mR, - 1 < x2 < 1, x1 and x2 are not both 0, m > 0;

[0045] Wherein, the input end is disposed on the main concave mirror or the main plane mirror, the output end is disposed on the main concave mirror, the main plane mirror or the sub-mirror, and the reflecting surfaces of the main concave mirror, the main plane mirror and the sub-mirror are opposite and spaced apart to form a reflection cavity. The optical axis of the reflection cavity is perpendicular to the reflecting surface of the plane mirror and passes through the optical center and the focus of the main concave mirror.

[0046] In an embodiment of the present application, an optical multipass cell including a main concave mirror, a main plane mirror, and a sub-mirror is provided. During each data acquisition process in the detection process of gas absorption data, based on the driving mechanism driving the sub-mirror to move periodically back and forth along the Z-axis direction parallel to the optical axis of the optical multipass cell, it is possible to obtain interference beams at different positions of the M sub-mirrors at the output end without significantly increasing the volume of the optical multipass cell system. Based on these interference beams, gas absorption data with smoothed optical noise can be obtained, thereby improving the sensitivity when detecting gas absorption data based on the optical multipass cell system.

[0047] In one embodiment, the Z-axis direction includes a positive Z-axis direction and a negative Z-axis direction that are parallel and opposite;

[0048] The position change value when the sub-mirror moves along the positive Z-axis direction is positive;

[0049] The position change value when the sub-mirror moves along the negative Z-axis direction is negative;

[0050] When the M sub-mirrors move periodically back and forth along the Z-axis direction,

[0051] Wherein, δ represents the sum of the position change values of the M sub-mirrors in the Z-axis direction, and λ represents the wavelength of the detection beam.

[0052] In an embodiment of the present application, by limiting the sum of the position change values of the M sub-mirrors in the Z-axis direction within the range of 0.25 to 10 times the wavelength of the detection beam when the M sub-mirrors move periodically back and forth along the Z-axis direction, when the wavelength range of the detection beam is within 0.2 μm to 12 μm, the position change range of the sub-mirror in the Z-axis direction is on the micron scale, and a micro-driving mechanism on the micron scale can be used for the driving mechanism, thereby effectively reducing the volume of the optical multipass cell system.

[0053] A second aspect of the embodiments of the present application provides a method for detecting gas absorption data, which is implemented based on the optical multipass cell system provided in the fourth implementation manner of the first aspect. The method for detecting gas absorption data includes:

[0054] During each data acquisition process of the detection process, control the driving mechanism to drive the M sub-reflectors of the optical multipass cell to move periodically back and forth along the Z-axis direction;

[0055] Obtain the actual light intensity of the interference beam output from the output end;

[0056] According to the actual light intensity, obtain the spectral transmittance function of the gas to be detected;

[0057] According to the spectral transmittance function, obtain the gas absorption data of the gas to be detected with noise smoothing.

[0058] In a second aspect of the embodiments of the present application, by providing a gas absorption data detection method, during each data acquisition process of the detection process, control the driving mechanism to drive the M sub-reflectors of the optical multipass cell to move periodically back and forth along the Z-axis direction, obtain the interference beams at different positions of the M sub-reflectors at the output end, and based on the actual light intensities of these interference beams, obtain the spectral transmittance function of the gas to be detected, so that the gas absorption data of the gas to be detected with optical noise smoothing can be obtained according to the spectral transmittance function.

[0059] In one embodiment, the gas absorption data detection method is implemented based on the maximum and minimum value method of the direct absorption method, and the wavelength of the detection beam is constant during each data acquisition process;

[0060] Obtaining the spectral transmittance function of the gas to be detected according to the actual light intensity includes:

[0061] According to the maximum and minimum values of all the actual light intensities obtained during each data acquisition process, obtain the spectral transmittance function of the gas to be detected;

[0062] Wherein,

[0063] The embodiments of the present application implement the gas absorption data detection method based on the maximum and minimum value method of the direct absorption method, set the wavelength of the detection beam to a constant wavelength during each data acquisition process, and limit the sum of the position change values in the Z-axis direction within the range of 0.5 to 10 times the wavelength of the detection beam when the M sub-reflectors move periodically back and forth along the Z-axis direction, without requiring the sum of the position change values to be an integer multiple of 0.5 times the wavelength of the detection beam. The control accuracy requirement for the driving mechanism is low. Directly according to the maximum and minimum values of all the actual light intensities obtained during each data acquisition process, obtain the spectral transmittance function of the gas to be detected. The algorithm is simple and the calculation amount is small, which can effectively improve the detection efficiency.

[0064] In one embodiment, the expression of the spectral transmittance function is:

[0065]

[0066] Among them, S(λ) represents the spectral transmittance function, Out(λ,δ) represents the actual light intensity, max(Out(λ,δ)) represents the maximum value among all the actual light intensities, and min(Out(λ,δ)) represents the minimum value among all the actual light intensities.

[0067] In one embodiment, the gas absorption data detection method is implemented based on the average value method of the direct absorption method, and the wavelength of the detection beam is constant during each data acquisition process;

[0068] Obtaining the spectral transmittance function of the gas to be detected according to the actual light intensity includes:

[0069] Obtaining the spectral transmittance function of the gas to be detected according to the average value of the actual light intensity at the sum of N different position change values obtained during each data acquisition process;

[0070] Among them, δ μ =(μ - 1)δ0, μ = 1, 2, 3, …, N, δ0 > 0 and δ0 is a constant, N ≥ 2;

[0071] δ μ represents the sum of the μth position change values among the sum of N different position change values, and δ N represents the maximum value among the sum of N different position change values.

[0072] In the embodiment of the present application, the gas absorption data detection method is implemented based on the average value method of the direct absorption method. The wavelength of the detection beam is set to a constant wavelength during each data acquisition process. When M sub-mirrors move back and forth periodically along the Z-axis direction, the sum of N position change values in the Z-axis direction is set to linearly change and is within the range of 0.25 to 10 times the wavelength of the detection beam. Then, according to the average value of the actual light intensity at the sum of N different position change values obtained during each data acquisition process, the spectral transmittance function of the gas to be detected is obtained, which can effectively improve the accuracy of the detection efficiency.

[0073] In one embodiment, the expression of the spectral transmittance function is:

[0074]

[0075] Among them,

[0076] N = mk;

[0077]

[0078] S(λ) represents the spectral transmittance function, and Out(λ,δ μ ) represents the actual light intensity at the sum of the μ-th position change values.

[0079] In one embodiment, the gas absorption data detection method is implemented based on the average value method of the harmonic method. During each data acquisition process, the wavelength of the detection beam varies within a preset wavelength modulation range;

[0080] Obtaining the spectral transmittance function of the gas to be detected according to the actual light intensity includes:

[0081] According to the actual light intensity at the sum of N different position change values obtained during each data acquisition process, obtain the corresponding harmonic spectral functions at the sum of N different position change values;

[0082] According to the average value of the harmonic spectral functions at the sum of the N different position change values, obtain the spectral transmittance function of the gas to be detected;

[0083] Wherein, the preset wavelength modulation range is within the preset wavelength range, δμ = (μ - 1)δ0, μ = 1, 2, 3, …, N, δ0 > 0 and δ0 is a constant, N ≥ 2;

[0084] δ μ represents the sum of the μ-th position change values among the sum of the N different position change values, and δ N represents the maximum value among the sum of the N different position change values.

[0085] In the embodiment of the present application, the gas absorption data detection method is implemented based on the average value method of the harmonic method. The wavelength of the detection beam is set to vary within a preset wavelength modulation range during each data acquisition process. When M sub-mirrors move periodically back and forth along the Z-axis direction, the sum of N position change values in the Z-axis direction is set to vary linearly and is within the range of 0.25 to 10 times the wavelength of the detection beam. Then, according to the actual light intensity at the sum of N different position change values obtained during each data acquisition process, obtain the corresponding harmonic spectral functions at the sum of N different position change values, and then according to the average value of the harmonic spectral functions at the sum of N different position change values, obtain the spectral transmittance function of the gas to be detected, which can effectively improve the accuracy of the detection efficiency.

[0086] In one embodiment, the expression for the average value of the harmonic spectral functions at the sum of the N different position change values is:

[0087]

[0088] Wherein,

[0089] N = mk;

[0090]

[0091] H m (λ) represents the average value of the harmonic spectral function at the sum of the N different position change values, S(λ + αφ) represents the spectral transmittance function, α represents the wavelength modulation coefficient of the detection beam, φ represents the wavelength modulation parameter of the light source device for emitting the detection beam, and n represents the harmonic order. represents the phase shift corresponding to the nth harmonic.

[0092] The third aspect of the embodiments of the present application provides a terminal device, including a memory, a processor, and a computer program stored in the memory and executable on the processor. When the processor executes the computer program, the steps of the gas absorption data detection method provided in the second aspect of the embodiments of the present application are implemented.

[0093] The fourth aspect of the embodiments of the present application provides a computer-readable storage medium. The computer-readable storage medium stores a computer program, and when the computer program is executed by a processor, the steps of the gas absorption data detection method provided in the second aspect of the embodiments of the present application are implemented.

[0094] It can be understood that the beneficial effects of the above third aspect and fourth aspect can refer to the relevant descriptions in the above second aspect, and will not be repeated here. Description of the Drawings

[0095] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the following will briefly introduce the drawings required for use in the embodiments or the description of the prior art. Obviously, the following drawings are only some embodiments of the present application. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on these drawings.

[0096] Figure 1 is a schematic structural diagram of the first optical multi-pass cell provided in the first embodiment of the present application;

[0097] Figure 2 is a schematic structural diagram of the second optical multi-pass cell provided in the first embodiment of the present application;

[0098] Figure 3 is a schematic structural diagram of the third optical multi-pass cell provided in the first embodiment of the present application;

[0099] Figure 4 is a schematic structural diagram of the fourth optical multi-pass cell provided in the first embodiment of the present application;

[0100] Figure 5 It is a schematic structural diagram of the fifth optical multi-pass cell provided in the first embodiment of the present application;

[0101] Figure 6 It is a schematic structural diagram of the sixth optical multi-pass cell provided in the first embodiment of the present application;

[0102] Figure 7 It is a schematic flow diagram of the gas absorption data detection method provided in the second embodiment of the present application. Detailed implementation manners

[0103] In the following description, specific details such as specific device structures and technologies are presented for the purpose of illustration rather than limitation, so as to thoroughly understand the embodiments of the present application. However, those skilled in the art should clearly understand that the present application can also be implemented in other embodiments without these specific details. In other cases, detailed descriptions of well-known devices, devices, circuits, and methods are omitted to avoid unnecessary details from interfering with the description of the present application.

[0104] It should be understood that when used in the specification of the present application and the appended claims, the term "comprising" indicates the presence of the described features, wholes, steps, operations, elements, and / or components, but does not exclude the presence or addition of one or more other features, wholes, steps, operations, elements, components, and / or their combinations.

[0105] It should also be understood that the term "and / or" used in the specification of the present application and the appended claims refers to any combination and all possible combinations of one or more of the associated listed items, and includes these combinations.

[0106] As used in the specification of the present application and the appended claims, the term "if" can be interpreted as "when", "once", "in response to determining", or "in response to detecting" depending on the context. Similarly, the phrase "if determined" or "if [the described condition or event] is detected" can be interpreted as meaning "once determined", "in response to determining", "once [the described condition or event] is detected", or "in response to detecting [the described condition or event]" depending on the context.

[0107] In addition, in the description of the specification of the present application and the appended claims, the terms "first", "second", "third", etc. are only used for distinguishing descriptions and cannot be understood as indicating or implying relative importance.

[0108] References to "one embodiment" or "some embodiments" etc. described in the specification of this application mean that specific features, structures, or characteristics described in connection with that embodiment are included in one or more embodiments of this application. Thus, statements such as "in one embodiment", "in some embodiments", "in other some embodiments", "in still other embodiments", etc. that appear in different places in this specification do not necessarily all refer to the same embodiment, but mean "one or more but not all embodiments", unless otherwise specifically emphasized in another way. The terms "comprising", "including", "having" and their variants all mean "including but not limited to", unless otherwise specifically emphasized in another way.

[0109] Embodiment 1

[0110] An embodiment of this application provides an optical multi-pass cell system, comprising:

[0111] An optical multi-pass cell, including an input end and an output end; and

[0112] A driving mechanism for driving M sub-mirrors of the optical multi-pass cell to move periodically back and forth along the Z-axis direction during each data acquisition process in the detection process of gas absorption data, where the Z-axis direction is parallel to the optical axis of the optical multi-pass cell;

[0113] Wherein, M≥1, and the detection process is: when the optical multi-pass cell is filled with the gas to be detected, the detection beam is input from the input end, and after multiple reflections in the optical multi-pass cell, an interference beam is output from the output end. During the entire detection process, the wavelength of the detection beam varies within a preset wavelength range, and the wavelength of the detection beam is constant or varies within a preset wavelength modulation range during each data acquisition process.

[0114] In application, the structure of the optical multi-pass cell can be set according to actual needs, and the number of sub-mirrors of the optical multi-pass cell is greater than or equal to M. The driving mechanism can be implemented based on a piezoelectric ceramic type or electromagnetic type driver. During the detection process, the wavelength of the detection beam varies within a preset wavelength range, and the wavelength of the detection beam is controlled to remain constant or vary within a preset wavelength modulation range during each data acquisition process, so that during each data acquisition process, according to the actual light intensity of the interference beam corresponding to the detection beam at each wavelength output from the output end, signal processing can be performed to obtain the spectral transmittance function. The preset wavelength range and the preset wavelength modulation range can both be set according to actual needs. For example, the preset wavelength range is 0.2um to 12um from ultraviolet light wavelength to mid-infrared light wavelength, and the wavelength of the detection beam after modulation within the preset wavelength modulation range is still within the preset wavelength range.

[0115] In the optical multipass cell system provided by the embodiments of the present application, during each data acquisition process in the detection process of gas absorption data, the driving mechanism drives the M sub-reflectors to move periodically back and forth along the Z-axis direction, which can change the distance between the optical center of the sub-reflector and the main reflector opposite thereto, thereby changing the single-pass optical path when the detection beam is reflected between the M sub-reflectors and the main reflector opposite thereto. As a result, interference beams at different positions of the M sub-reflectors can be obtained at the output end. Based on these interference beams, gas absorption data with smoothed optical noise can be obtained, thereby improving the sensitivity when detecting gas absorption data based on the optical multipass cell system.

[0116] As Figure 1 shown, in one embodiment, a first optical multipass cell system is provided, including an optical multipass cell 11 and a driving mechanism 12. The optical multipass cell 11 includes:

[0117] An input end 101 for inputting a detection beam;

[0118] An output end 102 for outputting an interference beam;

[0119] A main concave mirror 103; and

[0120] A first sub-reflector 104 and a second sub-reflector 105. Both the first sub-reflector 104 and the second sub-reflector 105 are concave mirrors. The reflecting surface of the main concave mirror 103 is opposite to and spaced from the reflecting surfaces of the first sub-reflector 104 and the second sub-reflector 105 to form a reflection cavity. The optical axis 106 of the reflection cavity is perpendicular to the focal plane of the main concave mirror 103;

[0121] Among them, both the input end 101 and the output end 102 are provided on the main concave mirror 103;

[0122] The driving mechanism 12 is used to drive the first sub-reflector 104 to move periodically back and forth along the Z-axis direction during each data acquisition process in the detection process of gas absorption data. The Z-axis direction is parallel to the optical axis 106;

[0123] The detection process is as follows: When the reflection cavity of the optical multipass cell 11 is filled with the gas to be detected, the detection beam is input from the input end 101, forms an interference beam after multiple reflections in the optical multipass cell 11, and is output from the output end 102. During the entire detection process, the wavelength of the detection beam changes within a preset wavelength range, and the wavelength of the detection beam is constant or changes within a preset wavelength modulation range during each data acquisition process.

[0124] In application, the output end 102 can be provided on the main concave mirror 103, the first sub-reflector 104, or the second sub-reflector 105. Figure 1Exemplarily, it is shown that the output end 102 is disposed on the main concave mirror 103. The sizes of the first sub-mirror 104 and the second sub-mirror 105 may be the same or different, and can be set according to actual needs. The driving mechanism 12 can be used to drive the first sub-mirror 104 or the second sub-mirror 105 to move independently, or can be used to drive the first sub-mirror 104 and the second sub-mirror 105 to move simultaneously. When the driving mechanism 12 drives the first sub-mirror 104 and the second sub-mirror 105 simultaneously, the driving mechanism 12 may include two drivers for driving the first sub-mirror 104 and the second sub-mirror 105 to move respectively.

[0125] Figure 1 Exemplarily, it is shown that the output end 102 is disposed on the main concave mirror 103, and the driving mechanism 12 is used to drive the first sub-mirror 104 to move independently.

[0126] In an embodiment of the present application, by providing an optical multipass cell including a main concave mirror and two sub-mirrors, in each data acquisition process of the gas absorption data detection process, based on the driving mechanism driving at least one of the two sub-mirrors of the optical multipass cell to periodically move back and forth along the Z-axis direction parallel to the optical axis of the optical multipass cell, it is possible to obtain interference beams at different positions of the M sub-mirrors at the output end without significantly increasing the volume of the optical multipass cell system. Based on these interference beams, gas absorption data with smoothed optical noise can be obtained, thereby improving the sensitivity when detecting gas absorption data based on the optical multipass cell system.

[0127] Such as Figure 2 、 Figure 3 、 Figure 4 Or Figure 5 As shown, in one embodiment, a second optical multipass cell system is provided, including an optical multipass cell 21 and a driving mechanism 22. The optical multipass cell 21 includes:

[0128] An input end 201 for inputting a detection beam;

[0129] An output end 202 for outputting an interference beam;

[0130] A main concave mirror 203;

[0131] A main plane mirror 204, the reflecting surface of the main concave mirror 203 and the reflecting surface of the main plane mirror 204 are opposite and spaced apart to form a reflection cavity, and the optical axis 206 of the reflection cavity is perpendicular to the focal plane 205 of the main concave mirror 203; and

[0132] N sub-mirrors, the N sub-mirrors are disposed on the main plane mirror 204, and the reflecting surfaces of the N sub-mirrors face the main concave mirror 203;

[0133] Wherein, N≥M, the input end 201 and the output end 202 are arranged on the main planar mirror 204;

[0134] The driving mechanism 200 is used to drive at least one sub-mirror to move periodically back and forth along the Z-axis direction during each data acquisition process in the detection process of gas absorption data, and the Z-axis direction is parallel to the optical axis 206;

[0135] The detection process is as follows: when the reflection cavity of the optical multipass cell 200 is filled with the gas to be detected, the detection beam is input from the input end 201, and after multiple reflections in the optical multipass cell 200, an interference beam is output from the output end 202. During the entire detection process, the wavelength of the detection beam changes within a preset wavelength range, and the wavelength of the detection beam is constant or changes within a preset wavelength modulation range during each data acquisition process.

[0136] In applications, the number of N and the type of the reflecting surface can be set according to actual needs. For example, 1, 2, 3, 4. The input end 201 can be arranged on the main concave mirror 203 or the main planar mirror 204, and the output end 202 can be arranged on the main concave mirror 203, the main planar mirror 204 or any sub-mirror. Figure 2 , Figure 3 , Figure 4 and Figure 5 exemplarily shows that both the input end 201 and the output end 202 are arranged on the main planar mirror 204. The driving mechanism 22 can be used to drive any sub-mirror to move alone, or can be used to drive multiple sub-mirrors to move simultaneously. When the driving mechanism 22 drives multiple sub-mirrors simultaneously, the driving mechanism 22 can include multiple drivers for driving each sub-mirror to move respectively.

[0137] Figure 2 exemplarily shows that N = 1, that is, the optical multipass cell 21 includes a first sub-mirror 207. The first sub-mirror 207 is a planar mirror with an area smaller than that of the main planar mirror 204. The inclination angle between the normal of the first sub-mirror 207 and the normal of the main planar mirror 204 is θ1 and the inclination angle θ1 is not zero. The driving mechanism 22 is used to drive the first sub-mirror 207 to move.

[0138] Figure 3Exemplarily, N = 2 is shown, that is, the optical multipass cell 21 includes a first sub - mirror 207 and a second sub - mirror 208. Both the first sub - mirror 207 and the second sub - mirror 208 are plane mirrors with an area smaller than that of the main - plane mirror 204. The inclination angle between the normal of the first sub - mirror 207 and the normal of the main - plane mirror 204 is θ1 and the inclination angle θ1 is non - zero. The normal of the second sub - mirror 208 is parallel to the normal of the main - plane mirror 204. The second sub - mirror 208 and the first sub - mirror 207 are symmetric about the origin 209 and are separated. The origin 209 is the intersection point of the optical axis 206 on the focal plane 205. The driving mechanism 22 is used to drive the second sub - mirror 208 to move.

[0139] Figure 4 Exemplarily, N = 2 is shown, that is, the optical multipass cell 21 includes a first sub - mirror 207 and a second sub - mirror 208. Both the first sub - mirror 207 and the second sub - mirror 208 are plane mirrors with an area smaller than that of the main - plane mirror 204. The inclination angle between the normal of the first sub - mirror 207 and the normal of the main - plane mirror 204 is θ1 and the inclination angle θ1 is non - zero. The normal of the second sub - mirror 208 is parallel to the normal of the main - plane mirror 204. The second sub - mirror 208 and the first sub - mirror 207 are symmetric about the origin 209 and are adjacent. The origin 209 is the intersection point of the optical axis 206 on the focal plane 205. The driving mechanism 22 is used to drive the first sub - mirror 207 and the second sub - mirror 208 to move simultaneously.

[0140] Figure 5 Exemplarily, N = 2 is shown, that is, the optical multipass cell 21 includes a first sub - mirror 207 and a second sub - mirror 208. Both the first sub - mirror 207 and the second sub - mirror 208 are plane mirrors with an area smaller than that of the main - plane mirror 204. The inclination angle between the normal of the first sub - mirror 207 and the normal of the main - plane mirror 204 is θ1 and the inclination angle θ1 is non - zero. The inclination angle between the normal of the second sub - mirror 208 and the normal of the main - plane mirror 204 is θ2 and the inclination angle θ2 is non - zero. The second sub - mirror 208 and the first sub - mirror 207 are symmetric about the origin 209 and are adjacent. The origin 209 is the intersection point of the optical axis 206 on the focal plane 205. The driving mechanism 22 is used to drive the first sub - mirror 207 and the second sub - mirror 208 to move simultaneously.

[0141] In applications, the inclination angle θ1 and the inclination angle θ2 can be equal or unequal. Figure 5 The shown first sub - mirror 207 and second sub - mirror 208 can be replaced by a roof prism. Compared with driving two independent sub - mirrors simultaneously, during the process of the driving mechanism 22 driving the roof prism to move, the stability is higher.

[0142] In an embodiment of the present application, an optical multipass cell including a main concave mirror, a main plane mirror, and N sub - mirrors is provided. During each data acquisition process in the detection process of gas absorption data, based on the driving mechanism, M of the N sub - mirrors of the optical multipass cell are driven to move periodically back and forth along the Z - axis direction parallel to the optical axis of the optical multipass cell. Without significantly increasing the volume of the optical multipass cell system, interference beams at different positions of the M sub - mirrors can be obtained at the output end. Based on these interference beams, gas absorption data with smoothed optical noise can be obtained, thereby improving the sensitivity when detecting gas absorption data based on the optical multipass cell system.

[0143] As Figure 6 shown, in one embodiment, a third optical multipass cell system is provided, including an optical multipass cell 31 and a driving mechanism 32. The optical multipass cell 31 includes:

[0144] An input end 301 for inputting a detection beam;

[0145] An output end 302 for outputting an interference beam;

[0146] A main concave mirror 303 with a focal length of f, a radius of curvature of R, and having aberration;

[0147] A main plane mirror 304, the distance from the reflecting surface of the main plane mirror 304 to the optical center of the main concave mirror 303 is L1=(1 + x1)f, - 1 < x1 < 1; and

[0148] A sub - mirror 305, the sub - mirror 305 is a concave mirror with a focal length of f0, a radius of curvature of R0, and is disposed on the main plane mirror 304. The area of the positive projection of the reflecting surface of the sub - mirror 305 on the reflecting surface of the main plane mirror 304 is smaller than the area of the reflecting surface of the main plane mirror 304. The distance from the optical center of the sub - mirror 305 to the optical center of the main concave mirror 303 is L2=(1 + x2)f, R0 = mR, - 1 < x2 < 1, x1 and x2 are not both 0, m > 0;

[0149] Among them, both the input end 301 and the output end 302 are disposed on the main concave mirror 303. The reflecting surface of the main concave mirror 303 is opposite to and spaced from the reflecting surfaces of the main plane mirror 304 and the sub - mirror 305 to form a reflection cavity. The optical axis 306 of the reflection cavity is perpendicular to the reflecting surface of the main plane mirror 304 and passes through the optical center and the focus of the main concave mirror 303;

[0150] The driving mechanism 12 is used to drive the sub - mirror 305 to move periodically back and forth along the Z - axis direction during each data acquisition process in the detection process of gas absorption data, and the Z - axis direction is parallel to the optical axis 306;

[0151] The detection process is as follows: when the reflection cavity of the optical multi-pass cell 31 is filled with the gas to be detected, the detection light beam is input from the input end 301, and after multiple reflections in the optical multi-pass cell 31, an interference light beam is formed and output from the output end 302. During the entire detection process, the wavelength of the detection light beam varies within a preset wavelength range, and during each data acquisition process, the wavelength of the detection light beam is constant or varies within a preset wavelength modulation range.

[0152] In application, the input end 301 can be arranged at the main concave reflector 303 or the main plane reflector 304, and the output end 302 can be arranged at the main concave reflector 303, the main plane reflector 304 or the sub-reflector 305. Figure 6 It is exemplarily shown in FIG. 3 that both the input end 301 and the output end 302 are arranged on the main concave reflecting mirror 303 .

[0153] The embodiment of the present application provides an optical multi-pass cell including a main concave reflector, a main plane reflector and a sub-reflector. During each data collection process of the detection process of gas absorption data, a driving mechanism drives the sub-reflector to periodically reciprocate along the Z-axis direction parallel to the optical axis of the optical multi-pass cell. Interference light beams of M sub-reflectors at different positions can be obtained at the output end without significantly increasing the volume of the optical multi-pass cell system. Based on these interference light beams, gas absorption data with smoothed optical noise can be obtained, thereby improving the sensitivity of detecting gas absorption data based on the optical multi-pass cell system.

[0154] In applications, the input end can be a fiber collimator with pigtails, a fiber collimator array, a light hole or an open angle on the main reflector, or a light-emitting device directly connected to the optical fiber; the output end can be a fiber collimator with pigtails, a fiber collimator array, a light hole or an open angle on the main reflector or sub-reflector, or a light detector directly connected to the optical fiber. The form of the light hole and the open angle is suitable for inputting incoherent detection beams with large divergence angles; for coherent detection beams with small divergence angles, such as lasers, a fiber collimator with pigtails is selected as the light input end, and a fiber collimator with pigtails is selected as the output end accordingly, or a light detector can be selected to directly receive the beam.

[0155] In applications, the input end and the output end may overlap to form an input-output end, and the input-output end is arranged on the main reflector or the sub-reflector;

[0156] Alternatively, the input end and the output end are separately arranged and both are arranged on the main reflector or the sub-reflector;

[0157] Alternatively, the input end and the output end are separately arranged, the input end is arranged on the main reflector, and the output end is arranged on the sub-reflector or the output end is the sub-reflector;

[0158] Alternatively, the input end and the output end are separately arranged, the input end is arranged on the sub-mirror, and the output end is arranged on the main mirror or the output end is the main mirror.

[0159] In applications, the positions of the input end and the output end can coincide or be separated. When the positions of the input end and the output end coincide, the two are the same and defined as the input-output end, and the input-output end can be arranged on the main mirror or any sub-mirror. When the positions of the input end and the output end are separated, the two can be arranged on the same mirror or on different mirrors. When the output end is the main mirror or the sub-mirror itself, the output end includes all the reflection areas of the main mirror or the sub-mirror.

[0160] In applications, the driving mechanism can include a motor and a driver. The motor is used for mechanical connection with the sub-mirror to be driven, and the driver is used for electrical connection with the motor to drive the motor to move. The driver can be a piezoelectric ceramic driver, a micro-motor system driver, a magnetostrictive driver or a voice coil motor driver.

[0161] In one embodiment, the Z-axis direction includes a positive Z-axis direction and a negative Z-axis direction that are parallel and opposite;

[0162] The position change value when the sub-mirror moves in the positive Z-axis direction is positive;

[0163] The position change value when the sub-mirror moves in the negative Z-axis direction is negative;

[0164] When M sub-mirrors move periodically back and forth in the Z-axis direction,

[0165] wherein, δ represents the sum of the position change values of M sub-mirrors in the Z-axis direction, λ represents the wavelength of the detection beam, λ is a variable that varies within a preset wavelength range during the entire detection process, and λ remains constant or varies within a preset wavelength modulation range during each data acquisition process.

[0166] In applications, the range of the sum of the position change values of all the sub-mirrors driven by the driving mechanism in the Z-axis direction is 0.25 to 10 times the wavelength of the detection beam, which can be set according to actual needs.

[0167] Embodiment 2

[0168] An embodiment of the present application provides a gas absorption data detection method, which is implemented based on any one of the optical multipass cell systems in Embodiment 1. The gas absorption data detection method can be executed by a processor of a terminal device when running a computer program with corresponding functions. During each data acquisition process in the detection process, the driving mechanism is controlled to drive M sub-mirrors of the optical multipass cell to move periodically back and forth along the Z-axis direction, and interference beams at different positions of the M sub-mirrors are obtained at the output end. Based on the actual light intensities of these interference beams, the spectral transmittance function of the gas to be detected is obtained. Thus, the gas absorption data of the gas to be detected with smoothed optical noise can be obtained according to the spectral transmittance function. By using a micro-motion optical component (i.e., the driving mechanism and the sub-mirrors it drives), the sensitivity of the terminal device can be effectively increased by more than about 10 times.

[0169] In applications, optical noise refers to the fact that in the absence of the gas to be detected, the light intensity received at the output end of the optical multipass cell has a certain jitter with the change of the wavelength of the detection beam. It is manifested as the change of light intensity with wavelength and is called optical noise. Since the absorption spectroscopy technique infers the concentration of the gas to be detected by scanning the change in the intensity of the detection beam passing through the optical multipass cell with the gas to be detected, during the wavelength scanning of the detection beam, due to the existence of optical noise, the output light intensity also changes, manifested as false absorption peaks. The optical noise level determines the lower limit of the gas concentration that the terminal device can detect. By reducing the optical noise, the lower limit of the gas concentration that the terminal device can detect can be reduced, thereby improving the sensitivity of the terminal device.

[0170] In applications, the terminal device may include a memory, a processor, and a computer program stored in the memory and executable on the processor. When the processor executes the computer program, the steps of the gas absorption data detection method are implemented; among them, the processor may include a driving mechanism control unit and a signal processing unit, and may also include a laser driving unit; the driving mechanism control unit is used to be electrically connected to the driving mechanism to control the operation of the driving mechanism; the signal processing unit is used to be electrically connected to an optical detection device (for example, a photodetector or a spectrometer) to obtain the light intensity signal or spectral signal detected by the optical detection device, and perform signal processing to obtain data such as the spectral transmittance function and gas absorption data (for example, concentration) of the gas to be detected.

[0171] In applications, at least two of the drive mechanism control unit, the signal processing unit, and the laser drive unit may be integrated into one processing unit, or each unit may exist physically separately. Additionally, the specific names of the laser drive unit and the signal processing unit are only for the convenience of distinguishing each other and do not limit the protection scope of the present invention. The terminal device may also be integrated with at least one of the optical multipass cell system, the laser, and the optical detection device into one device (e.g., a gas detector), and can be set according to the positions of the input end and the output end of the optical multipass cell system in combination with actual needs.

[0172] In applications, the memory may be an internal storage unit of the terminal device in some embodiments, e.g., a hard disk or a memory, specifically, the memory of the processor. The memory may also be an external storage device of the terminal device in other embodiments, e.g., a plug-in hard disk, a Smart Media Card (SMC), a Secure Digital (SD) card, a Flash Card, etc. Further, the memory may also include both the internal storage unit and the external storage device of the terminal device. The memory is used to store the operating system, application programs, a Boot Loader, data, and other programs, e.g., the program code of a computer program. The memory may also be used to temporarily store the data that has been output or will be output.

[0173] In applications, the laser drive unit and the signal processing unit may be a Central Processing Unit (CPU), or may also be other general-purpose processors, Digital Signal Processors (DSPs), Application Specific Integrated Circuits (ASICs), Field-Programmable Gate Arrays (FPGAs), or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. The general-purpose processor may be a microprocessor or any conventional processor, etc.

[0174] In applications, the laser can be any type of tunable laser, for example, a tunable semiconductor laser such as a Fabry-Perot laser, a distributed feedback semiconductor laser, a distributed Bragg reflector laser, a vertical-cavity surface-emitting laser, and an external cavity tuned semiconductor laser.

[0175] like Figure 7 As shown, the gas absorption data detection method provided in the embodiment of the present application includes the following steps S1 to S4:

[0176] Step S1, in each data collection process of the detection process, controlling the driving mechanism to drive the M sub-reflecting mirrors of the optical multi-pass cell to periodically move back and forth along the Z-axis direction;

[0177] Step S2, obtaining the actual light intensity of the interference light beam output from the output end;

[0178] Step S3, obtaining the spectral transmittance function of the gas to be detected according to the actual light intensity;

[0179] Step S4: Obtain noise-smoothed gas absorption data of the gas to be detected according to the spectral transmittance function.

[0180] In the application, step S1 is executed by the driving mechanism control unit; steps S2 to S4 are executed by the signal processing unit, which obtains the actual light intensity of the interference light beam output from the output end based on the light detector, and then performs signal processing to obtain the spectral transmittance function and gas absorption data of the gas to be detected.

[0181] In one embodiment, during the execution of step S1, the laser driving unit controls the laser to output a detection beam to the input end, and the wavelength of the detection beam is constant or varies within a preset wavelength modulation range.

[0182] In one embodiment, the gas absorption data detection method is implemented based on the maximum and minimum value method of the direct absorption method, and the wavelength of the detection beam is constant during each data collection process;

[0183] Step S1 includes: in each data collection process of the detection process, controlling the driving mechanism to drive the M sub-reflectors of the optical multi-pass cell to periodically move back and forth along the Z-axis direction, so that the sum of the position change values ​​of the M sub-reflectors in the Z-axis direction is within the range of 0.5 to 10 times the wavelength of the detection beam, that is,

[0184]

[0185] Step S2 comprises: obtaining the actual light intensity of the interference light beam output from the output end during the process of the M sub-reflecting mirrors periodically moving back and forth along the Z-axis direction for one or more cycles;

[0186] Step S3 includes: obtaining the spectral transmittance function of the gas to be detected according to the maximum value and the minimum value of all actual light intensities obtained in each data collection process.

[0187] In the application, based on the maximum and minimum value method of the direct absorption method, in step S1, the expressions of the maximum and minimum values ​​of all actual light intensities are as follows:

[0188]

[0189] Among them, S(λ) represents the spectral transmittance function, Out(λ,δ) represents the actual light intensity, max(Out(λ,δ)) represents the maximum value of all actual light intensities, min(Out(λ,δ)) represents the minimum value of all actual light intensities, I(λ,δ) represents the theoretical light intensity of the interference beam, max(I(λ,δ)) represents the maximum value of all theoretical light intensities, min(I(λ,δ)) represents the minimum value of all theoretical light intensities, ε represents the amplitude of the interference beam and is a small quantity, and L represents the optical path difference between the interference beam and the detection beam.

[0190] In application, by solving formula 1 and formula 2 simultaneously, (1+2ε) and (1-2ε) can be calibrated and eliminated, and the expression of the spectral transmittance function is obtained as follows:

[0191]

[0192] In the application, the gas absorption data detection method is realized by the maximum and minimum method based on the direct absorption method, the wavelength of the detection light beam is set to a constant wavelength during each data collection process, and when the M sub-reflectors are periodically moved back and forth along the Z-axis direction, the sum of the position change values ​​in the Z-axis direction is limited to 0.5 to 10 times the wavelength of the detection light beam. The sum of the position change values ​​is not required to be an integer multiple of 0.5 times the wavelength of the detection light beam. The control accuracy requirement for the driving mechanism is low. The spectral transmittance function of the gas to be detected is directly obtained according to the maximum and minimum values ​​of all actual light intensities obtained during each data collection process. The algorithm is simple and the calculation amount is small, which can effectively improve the detection efficiency.

[0193] In one embodiment, the gas absorption data detection method is implemented based on the average value method of the direct absorption method, and the wavelength of the detection beam is constant during each data collection process;

[0194] Step S1 includes: during each data collection process of the detection process, controlling the driving mechanism to drive the M sub-reflectors of the optical multi-pass cell to periodically move back and forth along the Z-axis direction, so that the sum of the position change values ​​of the M sub-reflectors in the Z-axis direction changes to N different positions within the range of 0.25 to 10 times the wavelength of the detection beam, that is, δ μ =(μ-1)δ0, μ=1,2,3,…,N,δ0>0 and δ0 is a constant, N≥2;δ μ represents the sum of the μth position change value among the sum of N different position change values, δ N Indicates the maximum value among the sum of N different position change values;

[0195] Step S2 comprises: obtaining the actual light intensity of the interference light beam output from the output end during the process of the M sub-reflecting mirrors periodically moving back and forth along the Z-axis direction for one or more cycles;

[0196] Step S3 includes: obtaining the spectral transmittance function of the gas to be detected according to the average value of the actual light intensity at the sum of the change values ​​at N different positions obtained in each data collection process.

[0197] In the application, based on the average value method of the direct absorption method, in step S1, the average value of the actual light intensity at the sum of the change values ​​at N different positions is expressed as follows:

[0198]

[0199] Substituting formula 4 into formula 3, we get:

[0200]

[0201] Mathematically, it can be proved that when the maximum value δ in the sum of the change values ​​of N different positions is N , the number of position samples N and the sum of the μth position change value δ among the sum of N different position change values μ , when the following formulas 6 to 8 are satisfied, the sum of the cosine function in formula 5 is zero, and the 1 in the expression is accumulated N times, and the sum is N, and formula 9 can be obtained:

[0202]

[0203] N = mk (Formula 7)

[0204]

[0205] ave(Out(λ,δ))=S(λ)·1=S(λ)(Formula 9)

[0206] From formula 5 and formula 9, the expression of the spectral transmittance function can be obtained as follows:

[0207]

[0208] Among them, Out(λ,δ μ ) represents the actual light intensity at the sum of the change values ​​of the μth position, ave(Out(λ,δ)) represents the average value of the actual light intensity at the sum of the change values ​​of N different positions, I(λ,δ μ ) indicates that the sum of the position changes of the M sub-reflectors in the Z-axis direction is δ μ The theoretical intensity of the interfering beam.

[0209] The embodiment of the present application implements a gas absorption data detection method through an average value method based on a direct absorption method, sets the wavelength of the detection light beam to a constant wavelength during each data acquisition process, and sets the sum of N position change values ​​in the Z-axis direction to a linear change when M sub-reflectors are periodically moved back and forth along the Z-axis direction, and are all within the range of 0.25 to 10 times the wavelength of the detection light beam. Then, the spectral transmittance function of the gas to be detected is obtained based on the average value of the actual light intensity at the sum of N different position change values ​​obtained during each data acquisition process, which can effectively improve the accuracy of detection efficiency.

[0210] In one embodiment, the gas absorption data detection method is implemented based on the average value method of the harmonic method, and the wavelength of the detection beam changes within a preset wavelength modulation range during each data collection process;

[0211] Step S1 includes: during each data collection process of the detection process, controlling the driving mechanism to drive the M sub-reflectors of the optical multi-pass cell to periodically move back and forth along the Z-axis direction, so that the sum of the position change values ​​of the M sub-reflectors in the Z-axis direction changes to N different positions within the range of 0.25 to 10 times the wavelength of the detection beam, that is, δ μ =(μ-1)δ0, μ=1,2,3,…,N,δ0>0 and δ0 is a constant, N≥2;δ μ represents the sum of the μth position change value among the sum of the N different position change values, δ N represents the maximum value among the sums of the N different position change values;

[0212] Step S2 comprises: obtaining the actual light intensity of the interference light beam output from the output end during the process of the M sub-reflecting mirrors periodically moving back and forth along the Z-axis direction for one or more cycles;

[0213] Step S3 includes:

[0214] According to the actual light intensity at the sum of the N different position change values ​​obtained in each data collection process, the harmonic spectrum function at the sum of the corresponding N different position change values ​​is obtained;

[0215] According to the average value of the harmonic spectrum function at the sum of the change values ​​at N different positions, the spectral transmittance function of the gas to be detected is obtained, that is, the average value of the harmonic spectrum function at the sum of the change values ​​at N different positions is subjected to inverse Fourier transform to obtain the spectral transmittance function of the gas to be detected.

[0216] In the application, based on the average value method of the harmonic method, in step S3, the expression of the average value of the harmonic spectrum function at the sum of the change values ​​at N different positions is as follows:

[0217]

[0218] By exchanging the summation sign and the integral sign in formula 10, we can obtain:

[0219]

[0220] By analyzing the summation part in formula 11, we know that the wavelength modulation width αφ is much smaller than the wavelength λ, so:

[0221]

[0222] Mathematically, it can be proved that when the maximum value δ in the sum of the change values ​​of N different positions is N , the number of position samples N and the sum of the μth position change value δ among the sum of N different position change values μ , when the following formulas 13 to 15 are satisfied, the sum of the cosine function in formula 12 is zero, and the 1 in the expression is accumulated N times, and the sum is N, and formula 16 can be obtained:

[0223]

[0224] N = mk (Formula 14)

[0225]

[0226] By performing an inverse Fourier transform on formula 16, S(λ+αφ) can be obtained, eliminating the interference effect. Formula 16 is the harmonic spectrum line with the interference effect eliminated;

[0227] Where λ is the central wavelength of the probe beam, H n (λ,δ μ ) represents the harmonic spectrum function at the sum of the μth position change values, H n (λ) represents the average value of the harmonic spectrum function at the sum of the change values ​​at N different positions, S(λ+αφ) represents the spectral transmittance function, α represents the wavelength modulation coefficient of the detection beam, φ represents the wavelength modulation parameter of the light source device (e.g., laser) used to emit the detection beam, n represents the harmonic order, Indicates the phase shift corresponding to the n-th order harmonic.

[0228] In application, there are two equivalent signal processing methods based on the average value method of the harmonic method, which are as follows:

[0229] The first one: in each δ μ At, we get a set of harmonic spectrum functions Then, the average value of N groups of harmonic spectrum functions is obtained, and the following expression is obtained:

[0230]

[0231] The second type: At each central wavelength λ, for each δ μ Scan the wavelength αφ within the wavelength modulation range to obtain the theoretical light intensity of the interference beam, then calculate the average value ave(S(λ+αφ)) of the spectral transmittance function for N sets of wavelength data, and then solve the harmonic spectrum function according to the following expression:

[0232]

[0233] The embodiment of the present application implements a gas absorption data detection method through an average value method based on the harmonic method, and sets the wavelength of the detection light beam in each data collection process to change within a preset wavelength modulation range. When the M sub-reflectors are periodically moved back and forth along the Z-axis direction, the sum of the N position change values ​​in the Z-axis direction is set to change linearly and are all within the range of 0.25 to 10 times the wavelength of the detection light beam. Then, based on the actual light intensity at the sum of the N different position change values ​​obtained in each data collection process, the harmonic spectrum function at the corresponding sum of the N different position change values ​​is obtained, and then based on the average value of the harmonic spectrum function at the sum of the N different position change values, the spectral transmittance function of the gas to be detected is obtained, which can effectively improve the accuracy of the detection efficiency.

[0234] An embodiment of the present invention further provides a computer-readable storage medium, which stores a computer program. When the computer program is executed by a processor, the steps in the above-mentioned gas absorption data detection method embodiment can be implemented.

[0235] An embodiment of the present invention provides a computer program product. When the computer program product is executed on a terminal device, the terminal device can implement the steps in the above-mentioned gas absorption data detection method embodiment.

[0236] In applications, computer-readable media may include at least: any entity or device capable of carrying computer program codes to a terminal device, a recording medium, a computer memory, a read-only memory (ROM), a random access memory (RAM), an electric carrier signal, a telecommunication signal, and a software distribution medium. For example, a USB flash drive, a mobile hard disk, a magnetic disk, or an optical disk. In the above embodiments, the description of each embodiment has its own emphasis. For parts that are not described or recorded in detail in a certain embodiment, please refer to the relevant description of other embodiments.

[0237] Those of ordinary skill in the art will appreciate that the devices of each example described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are performed in hardware or software depends on the specific application and design constraints of the technical solution. Professional and technical personnel can use different methods to implement the described functions for each specific application, but such implementation should not be considered to be beyond the scope of this application.

[0238] In the embodiments provided in this application, it should be understood that the disclosed device can be implemented in other ways. For example, the device embodiments described above are only schematic, for example, the division of units is only a logical function division, and there may be other division methods in actual implementation, such as multiple devices can be combined or integrated.

[0239] The above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them. Although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. These modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present application, and should all be included in the protection scope of the present application.

Claims

1. An optical multi-pass cell system, characterized in that: include: An optical multipass cell, including an input end and an output end; as well as A driving mechanism, used for driving the M sub-reflectors of the optical multi-pass cell to periodically reciprocate along a Z-axis direction during each data collection process of the gas absorption data detection process, wherein the Z-axis direction is parallel to the optical axis of the optical multi-pass cell; Wherein, M≥1, and the detection process is: when the optical multi-pass cell is filled with the gas to be detected, a detection light beam is input from the input end, and after multiple reflections in the optical multi-pass cell, an interference light beam is formed and output from the output end. During the entire detection process, the wavelength of the detection light beam varies within a preset wavelength range, and during each data acquisition process, the wavelength of the detection light beam is constant or varies within a preset wavelength modulation range.

2. The optical multi-pass cell system according to claim 1, characterized in that: The optical multi-pass cell comprises: The input end is used to input a detection light beam; The output end is used to output an interference light beam; a primary concave reflector; and Two sub-reflectors, each of which is a concave reflector, a reflective surface of the main concave reflector and a reflective surface of the sub-reflectors are opposite to each other and are arranged at an interval to form a reflective cavity, and an optical axis of the reflective cavity is perpendicular to a focal plane of the main concave reflector; Wherein, the input end is arranged at the main concave reflector, and the output end is arranged at the main concave reflector or any of the sub-reflectors.

3. The optical multi-pass cell system according to claim 1, characterized in that: The optical multi-pass cell comprises: The input end is used to input a detection light beam; The output end is used to output an interference light beam; primary concave reflector; a main plane reflector, wherein the reflective surface of the main concave reflector is opposite to the reflective surface of the main plane reflector and is arranged at an interval to form a reflective cavity, and the optical axis of the reflective cavity is perpendicular to the focal plane of the main concave reflector; and N sub-reflectors, wherein the sub-reflectors are arranged on the main plane reflector, and the reflective surfaces of the N sub-reflectors are arranged toward the main concave reflector; Wherein, N≥M, the input end is arranged at the main concave reflector or the main plane reflector, and the output end is arranged at the main concave reflector, the main plane reflector or any of the sub-reflectors.

4. The optical multi-pass cell system according to claim 3, characterized in that: N=1, the sub-reflector is a plane reflector with an area smaller than that of the main plane reflector; The inclination angle between the normal line of the sub-reflector and the normal line of the main plane reflector is θ1, and the inclination angle θ1 is not zero; The driving mechanism is used to drive the sub-reflector to move.

5. The optical multi-pass cell system according to claim 3, characterized in that: N=2, the N sub-reflectors include a first sub-reflector and a second sub-reflector; The first sub-reflector and the second sub-reflector are both plane reflectors with an area smaller than that of the main plane reflector, and the inclination angle between the normal line of the first sub-reflector and the normal line of the main plane reflector is θ1, and the inclination angle θ1 is not zero; The normal line of the second sub-reflector is parallel to the normal line of the main plane reflector, the second sub-reflector and the first sub-reflector are symmetrical about an origin and are separately arranged, and the origin is the intersection point of the optical axis on the focal plane; The driving mechanism is used to drive the second sub-reflector to move.

6. The optical multi-pass cell system according to claim 3, characterized in that: N=2, the N sub-reflectors include a first sub-reflector and a second sub-reflector; The first sub - mirror and the second sub - mirror are both planar mirrors with areas smaller than that of the main planar mirror. The inclination angle between the normal of the first sub - mirror and the normal of the main planar mirror is θ1 and the inclination angle θ1 is non - zero; The normal of the second sub - mirror is parallel to the normal of the main planar mirror. The second sub - mirror and the first sub - mirror are symmetric about the origin and are adjacent to each other. The origin is the intersection point of the optical axis on the focal plane; The driving mechanism is used to drive the first sub - mirror and the second sub - mirror to move simultaneously.

7. The optical multi-pass cell system according to claim 3, characterized in that: N = 2, and the N sub - mirrors include the first sub - mirror and the second sub - mirror; The first sub - mirror and the second sub - mirror are both planar mirrors with areas smaller than that of the main planar mirror. The inclination angle between the normal of the first sub - mirror and the normal of the main planar mirror is θ1 and the inclination angle θ1 is non - zero; The inclination angle between the normal of the second sub - mirror and the normal of the main planar mirror is θ2 and the inclination angle θ2 is non - zero. The second sub - mirror and the first sub - mirror are symmetric about the origin and are adjacent to each other. The origin is the intersection point of the optical axis on the focal plane; The driving mechanism is used to drive the first sub - mirror and the second sub - mirror to move simultaneously.

8. The optical multi-pass cell system according to claim 1, wherein: The optical multi - pass cell includes: The input end, which is used to input the probe beam; The output end, which is used to output the interference beam; The main concave mirror, with a focal length of f, a radius of curvature of R and having aberration; The main planar mirror, the distance from the reflecting surface of the main planar mirror to the optical center of the main concave mirror is L1=(1 + x1)f, - 1 < x1 < 1; and The sub - mirror, which is a concave mirror with a focal length of f0, a radius of curvature of R0 and is arranged on the main planar mirror. The orthographic projection area of the reflecting surface of the sub - mirror on the reflecting surface of the main planar mirror is smaller than the area of the reflecting surface of the main planar mirror. The distance from the optical center of the sub - mirror to the optical center of the main concave mirror is L2=(1 + x2)f, R0 = mR, - 1 < x1 < 1, x1 and x2 are not both 0, m > 0; Wherein, the input end is arranged on the main concave mirror or the main planar mirror, the output end is arranged on the main concave mirror, the main planar mirror or the sub - mirror. The reflecting surface of the main concave mirror is opposite to and spaced from the reflecting surfaces of the main planar mirror and the sub - mirror to form a reflection cavity. The optical axis of the reflection cavity is perpendicular to the reflecting surface of the planar mirror and passes through the optical center and the focus of the main concave mirror.

9. The optical multi-pass cell system according to any one of claims 1 to 8, characterized in that: The Z - axis direction includes the positive Z - axis direction and the negative Z - axis direction which are parallel and opposite; The position change value of the sub - mirror when moving along the positive Z - axis direction is positive; The position change value of the sub - mirror when moving along the negative Z - axis direction is negative; When the M sub-reflectors periodically move back and forth along the Z-axis direction, Wherein, δ represents the sum of the position change values of the M sub - mirrors in the Z - axis direction, and λ represents the wavelength of the probe beam.

10. The optical multi-pass cell system according to any one of claims 1 to 8, characterized in that: The preset wavelength range is 0.2um to 12um.

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