Photothermoelastic spectrum gas detection device and method based on incoherent fixed spectrum excitation

Abstract

The invention relates to a photoinduced thermoelastic spectrum gas detection device based on incoherent fixed spectrum excitation, which comprises an incoherent light source module used for generating incoherent light with controllable power and light intensity modulation depth; the optical shaping module is used for shaping the incoherent light beam and effectively coupling the incoherent light into the sampling module; the gas absorption module is internally provided with a gas accommodating cavity for storing to-be-detected gas; the uncorrelated light is absorbed by the gas to be detected and then forms periodic thermal deposition on the sampling module, and the sampling module is used for collecting thermal elastic stress generated by the periodic thermal deposition and converting the thermal elastic stress into an electric signal; and the signal amplification and demodulation module is used for extracting and demodulating the electric signals acquired by the sampling module. The incoherent fixed spectrum light source is more uniform in light field distribution, wide spectrum output can cover a plurality of absorption peaks in a fixed spectrum range, and the incoherent fixed spectrum light source is insensitive to wavelength drift.

Description

Technical Field

[0001] This invention relates to the fields of optical gas detection and photoelectric sensing technology, and in particular to a photothermal elastic spectroscopy gas detection device and method based on incoherent fixed spectral excitation. Background Technology

[0002] Optical gas detection, due to its advantages such as high sensitivity, strong selectivity, and fast response speed, has long been used in fields such as environmental monitoring, industrial leak early warning, medical diagnosis, and public safety. Among the many optical detection methods, light-induced thermoelastic spectroscopy (LITES) has attracted attention as a rapidly developing new detection technology in recent years due to its advantages such as not requiring an acoustic resonant cavity, simple structure, and strong environmental adaptability. Its core principle is that the incident light is absorbed by the gas, generating periodic changes in optical power. This change causes periodic temperature fluctuations on the surface of the sensitive material, resulting in thermoelastic stress disturbances, which are further converted into measurable electrical signals through an electromechanical conversion mechanism.

[0003] In traditional photothermoelastic spectroscopy schemes, coherent lasers such as distributed feedback lasers (DFB) and quantum cascade lasers (QCL) are typically used as the light source to precisely match the narrow linewidth output with specific absorption spectral lines. However, the high coherence and high directivity of lasers can easily introduce speckle noise and local spot hotspots, imposing stringent requirements on beam alignment, temperature stability, and drive current. This results in complex system structures, high costs, and high sensitivity to environmental disturbances. Summary of the Invention

[0004] This invention provides a photothermal elastic gas detection device and method based on incoherent fixed spectral excitation, aiming to solve at least one of the technical problems existing in the prior art.

[0005] The technical solution of this invention is a photothermal elastic gas detection device based on incoherent fixed spectral excitation, wherein the photothermal elastic gas detection device based on incoherent fixed spectral excitation comprises, in sequence: Incoherent light source module, used to generate incoherent light with controllable power and intensity modulation depth; An optical shaping module is used to shape incoherent beams and effectively couple incoherent light into the sampling module; A gas absorption module is provided with a gas container cavity for storing the gas to be tested. Uncorrelated light that has been shaped is incident on the gas container cavity, and the gas to be tested, which is pre-placed in the gas container cavity, absorbs the light energy of the uncorrelated light. The sampling module is used to collect the thermoelastic stress generated by the periodic thermal deposition of uncorrelated light after absorption by the gas under test, and convert it into an electrical signal. The signal amplification and demodulation module is used to extract, amplify, and demodulate the electrical signal acquired by the sampling module.

[0006] Furthermore, the uncorrelated light source module includes a function generator, a driver, and an incoherent fixed-spectrum light source connected in sequence. The function generator is used to output a periodic modulation signal, and the driver converts the modulation signal output by the function generator into a stable current to drive an incoherent fixed-spectrum light source. The incoherent fixed-spectrum light source generates broadband light with a fixed spectrum under the drive of the current output by the driver.

[0007] Furthermore, the incoherent fixed-spectrum light source is a broadband LED or a superluminescent diode (SLED).

[0008] Furthermore, the optical shaping module includes a collimating lens or an optical collimation system.

[0009] Furthermore, the gas-containing cavity of the gas absorption module is a gas absorption pool or an open sampling area. The gas absorption cell or the open sampling area contains the gas to be measured.

[0010] Furthermore, the sampling module is a photothermal detector or a pyroelectric detector.

[0011] Furthermore, the sampling module is a piezoelectric tuning fork, which receives thermoelastic stress and converts it into an electrical signal.

[0012] Furthermore, the signal amplification and demodulation module includes a preamplifier and a lock-in amplifier.

[0013] Furthermore, it also includes a data processing unit, which is used to control the process of the photothermal elastic gas detection device based on incoherent fixed spectral excitation and the output data of the acquisition signal amplification and demodulation module. The output of the data processing unit is connected to the input of the function generator of the unrelated light source module, and the data processing unit is used to control the output of the function generator; The input terminal of the data processing unit is electrically connected to the output of the signal amplification and demodulation module. The data processing unit collects the amplified electrical signal and analyzes it to obtain the physical characteristics of the gas to be tested.

[0014] Furthermore, this invention also proposes a control method for a photothermal elastic gas detection device based on incoherent fixed spectral excitation, applied to the aforementioned photothermal elastic gas detection device based on incoherent fixed spectral excitation. The control method for the photothermal elastic gas detection device based on incoherent fixed spectral excitation includes the following steps: Under the control of the data processing unit, the function generator of the S100 incoherent light source module outputs a periodic modulation signal. The driver converts the modulation signal into a stable current to drive the incoherent fixed spectrum light source, which then produces broadband light with a fixed spectrum. S200: The optical shaping module shapes the incoherent beam and effectively couples the incoherent light into the sampling module; S300, The gas to be tested in the gas-containing cavity absorbs the light energy of uncorrelated light; After the S400 broadband light is absorbed in the gas to be tested, the light energy is deposited on the sampling module in a periodic manner according to the modulation rhythm, thereby inducing periodic temperature rise and thermoelastic stress, generating a piezoelectric charge signal that varies with time. The S500 piezoelectric charge signal is amplified by the preamplifier of the signal amplification and demodulation module, and then the robust thermoelastic characteristic signal is extracted by the lock-in amplifier with reference to the function generator frequency and sent to the data processing unit for processing.

[0015] The beneficial effects of this invention include: The photothermoelastic gas detection device and method based on incoherent fixed spectral excitation described in this invention have significant advantages in photothermoelastic spectroscopy. The incoherent fixed spectral light source has a more uniform light field distribution, does not produce speckle, and can achieve smoother and more stable thermal deposition. Its broadband output can cover multiple absorption peaks within a fixed spectral range and is insensitive to wavelength drift. Light intensity modulation can be achieved through simple current modulation, easily obtaining a large intensity modulation depth. At the same time, this type of light source is low in cost, has a simple driving circuit, and is highly eye-safe, making it suitable for portable, miniaturized, and large-scale sensor array applications.

[0016] Furthermore, additional aspects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of a photothermal elastic gas detection device based on incoherent fixed spectral excitation according to an embodiment of the present invention.

[0018] Figure 2 This is a general flowchart of a photothermal elastic gas detection method based on incoherent fixed spectral excitation according to an embodiment of the present invention.

[0019] Figure 3 This is a schematic diagram of the absorption spectrum of NO2 detected by the photothermal elastic gas detection device based on incoherent fixed spectral excitation according to an embodiment of the present invention.

[0020] Figure 4 The figure shows the experimental results of photothermal elastic spectroscopy gas detection of NO2 using the detection system and a 450nm LED incoherent light source, according to an embodiment of the present invention. Detailed Implementation

[0021] The following will provide a clear and complete description of the concept, specific structure, and technical effects of the present invention in conjunction with the embodiments and accompanying drawings, so as to fully understand the purpose, solution, and effects of the present invention. It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other.

[0022] It should be noted that, unless otherwise specified, when a feature is referred to as "fixed" or "connected" to another feature, it can be directly fixed or connected to the other feature, or indirectly fixed or connected to the other feature. Furthermore, the descriptions of "upper," "lower," "left," "right," "top," and "bottom" used in this invention are only relative to the relative positional relationships of the various components of the invention in the accompanying drawings.

[0023] Furthermore, unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. The terminology used in this specification is for the purpose of describing particular embodiments only and not for limiting the invention. The term "and / or" as used herein includes any combination of one or more of the associated listed items.

[0024] It should be understood that although the terms first, second, third, etc., may be used in this disclosure to describe various elements, these elements should not be limited to these terms. These terms are only used to distinguish elements of the same type from one another. For example, without departing from the scope of this disclosure, a first element may also be referred to as a second element, and similarly, a second element may also be referred to as a first element.

[0025] Reference Figures 1 to 4 In some embodiments, the photothermal elastic gas detection device based on incoherent fixed spectral excitation according to the present invention comprises, in sequence: Incoherent light source module, used to generate incoherent light with controllable power and intensity modulation depth; An optical shaping module is used to shape incoherent beams and effectively couple incoherent light into the sampling module; A gas absorption module is provided with a gas container cavity for storing the gas to be tested. Uncorrelated light that has been shaped is incident on the gas container cavity, and the gas to be tested, which is pre-placed in the gas container cavity, absorbs the light energy of the uncorrelated light. The sampling module is used to collect the thermoelastic stress generated by the periodic thermal deposition of uncorrelated light after absorption by the gas under test, and convert it into an electrical signal. The signal amplification and demodulation module is used to extract, amplify, and demodulate the electrical signal acquired by the sampling module.

[0026] The beneficial effects of this invention include: The photothermoelastic gas detection device and method based on incoherent fixed spectral excitation described in this invention have significant advantages in photothermoelastic spectroscopy: the light field distribution is more uniform, no speckle is generated, and smoother and more stable thermal deposition can be achieved; the broadband output can cover multiple absorption peaks within a fixed spectral range and is not sensitive to wavelength drift; the light intensity modulation can be achieved through simple current modulation, and it is easy to obtain a large light intensity modulation depth; at the same time, this type of light source is low in cost, has a simple driving circuit, and is highly eye-safe, making it suitable for portable, miniaturized, and large-scale sensor array applications.

[0027] The photothermal elastic spectroscopy gas detection device based on incoherent fixed spectral excitation described in this invention belongs to the interdisciplinary field of optical absorption spectroscopy, thermoelastic sensing, and piezoelectric signal detection. It is a trace gas monitoring system that realizes gas concentration inversion through the thermoelastic deformation of the sensor. This technology belongs to the interdisciplinary field of optical absorption spectroscopy, thermoelastic sensing, and piezoelectric signal detection, and realizes gas concentration inversion through the thermoelastic deformation of the sensor. This invention aims to overcome the problems of high cost, strong dependence on wavelength stability, significant speckle noise, and high system complexity in existing photothermal elastic spectroscopy technology, and proposes a photothermal elastic spectroscopy gas detection device and method based on incoherent fixed spectral excitation.

[0028] This invention utilizes the broad spectral distribution, low coherence, and ease of intensity modulation of incoherent light sources (such as LEDs, SLEDs, and broadband light sources). This allows the light source to effectively excite gas absorption and generate photothermal elastic signals without requiring narrow linewidth, high coherence, or wavelength scanning capabilities, nor precise centering of the absorption line. In this way, the cost, structural complexity, and environmental sensitivity of the entire gas detection system are significantly reduced, while the system's stability, adaptability, and scalability are significantly improved.

[0029] In a photothermoelastic gas detection device based on incoherent fixed-spectral excitation, the incoherent light source module emits light radiation with a fixed spectral distribution. The intensity of this radiation is modulated by the optical shaping module to achieve periodic changes in light intensity. The modulated beam is then incident on the gas absorption module. After passing through the gas to be measured, the beam is absorbed by the gas, causing periodic thermal deposition and generating thermoelastic stress on the gas and detector surfaces that varies with the modulation frequency. The photothermal detector converts this mechanical response into an electrical signal. A lock-in amplifier demodulates the robust photothermoelastic signal at the modulation frequency or its harmonics, and the data processing unit then calculates the gas concentration.

[0030] Furthermore, refer to Figure 1 The uncorrelated light source module includes a function generator, a driver, and an incoherent fixed-spectrum light source connected in sequence. The function generator is used to output a periodic modulation signal, and the driver converts the modulation signal output by the function generator into a stable current to drive an incoherent fixed-spectrum light source. The incoherent fixed-spectrum light source generates broadband light with a fixed spectrum under the drive of the current output by the driver.

[0031] Furthermore, refer to Figure 1 The incoherent fixed spectral light source is a broadband LED or a superluminescent diode (SLED).

[0032] Specifically, compared to traditional photothermoelastic spectroscopy schemes, which typically use coherent lasers such as distributed feedback lasers (DFB) and quantum cascade lasers (QCL) as light sources to precisely match narrow linewidth output with specific absorption spectral lines, incoherent fixed-spectrum light sources (such as broadband LEDs, superluminescent diodes (SLEDs), or other broadband light sources) have significant advantages in photothermoelastic spectroscopy: their light field distribution is more uniform, without speckle, enabling smoother and more stable thermal deposition; their broadband output can cover multiple absorption peaks within a fixed spectral range and is insensitive to wavelength drift; intensity modulation can be achieved through simple current modulation, easily obtaining a large ΔI; at the same time, such light sources are low-cost, have simple driving circuits, and are highly eye-safe, making them suitable for portable, miniaturized, and large-scale sensor array applications.

[0033] Furthermore, refer to Figure 1 The optical shaping module includes a collimating lens or an optical collimation system.

[0034] Furthermore, refer to Figure 1 The gas-containing cavity of the gas absorption module is either a gas absorption pool or an open sampling area. The gas absorption cell or the open sampling area contains the gas to be measured.

[0035] Furthermore, refer to Figure 1The sampling module is a photothermal detector or a pyroelectric detector.

[0036] Specifically, the core principle of light-induced thermoelastic spectroscopy (LITES) is that incident light is absorbed by a gas, resulting in periodic changes in optical power. This change causes periodic temperature fluctuations on the surface of the sensitive material, leading to thermoelastic stress perturbations, which are then converted into measurable electrical signals via an electromechanical conversion mechanism. The physical mechanism can be expressed as follows: In the formula, The incident light power, To emphasize the depth of light, It is the absorption coefficient of the gas being measured at a specific wavelength.

[0037] Light source power The total light energy entering the gas being measured and the detector, and the modulation depth are determined. The absorption coefficient determines the rate at which light intensity changes over time. This reflects the gas's absorption capacity for the spectral components used. It clearly reveals that the photothermoelastic spectral signal primarily depends on changes in light intensity, rather than the coherence or wavelength stability of the light source. In other words, as long as the light source can generate sufficiently rapid changes in light intensity under modulation, and its spectrum contains some light energy absorbed by the target gas, a robust photothermoelastic signal can be generated, regardless of whether the light source has a narrow linewidth, monochromaticity, or long coherence length.

[0038] This relationship shows that photothermoelastic spectroscopy essentially depends only on periodic changes in light intensity and the absorption of the spectrum by the measured medium, and does not depend on the coherence of the light source or fine wavelength scanning. This lays the foundation for using incoherent fixed-spectrum light sources. Therefore, although incoherent light sources do not possess the coherence and wavelength tunability of lasers, they can easily and stably achieve 100% [optical efficiency] through current control, thanks to their large modulation depth, wide spectral coverage, and high power output. This effectively enhances the thermobomb signal.

[0039] The incoherent fixed-spectrum light source used in this invention can still obtain a significant photothermoelastic response without wavelength scanning, which also theoretically demonstrates that incoherent light sources can fully perform photothermoelastic excitation without having to meet the strict characteristic requirements of laser light sources.

[0040] By employing an incoherent fixed-spectral light source, this invention exhibits advantages over traditional laser photothermoelastic spectroscopy in several aspects. First, the incoherent light source does not introduce random thermal deposition noise caused by coherence, thus significantly reducing system noise and improving the signal-to-noise ratio. Second, the fixed spectral coverage is wide, eliminating the need for fine scanning of the light source wavelength. Furthermore, the incoherent light source is easy to modulate, low in cost, small in size, long in lifespan, and requires no precise temperature control or current locking, greatly improving the system's robustness and long-term stability. Simultaneously, its uniform spot characteristics reduce sensitivity to optical path alignment, making the device more suitable for portable, array-based, or large-scale deployment applications.

[0041] In summary, the photothermoelastic spectroscopy detection technology based on incoherent fixed spectral excitation proposed in this invention is not only significantly superior to traditional laser-based solutions in terms of structure and cost, but also has outstanding advantages in noise suppression, system stability, multi-gas adaptability, and practical application flexibility. It provides an innovative technical approach for low-cost, highly robust, and scalable gas detection.

[0042] Furthermore, refer to Figure 1 The sampling module is a piezoelectric tuning fork, which receives thermoelastic stress and converts it into an electrical signal.

[0043] Furthermore, refer to Figure 1 The signal amplification and demodulation module includes a preamplifier and a lock-in amplifier.

[0044] Furthermore, refer to Figure 1 It also includes a data processing unit, which is used to control the process of the photothermal elastic gas detection device based on incoherent fixed spectral excitation and the output data of the acquisition signal amplification and demodulation module. The output of the data processing unit is connected to the input of the function generator of the unrelated light source module, and the data processing unit is used to control the output of the function generator; The input terminal of the data processing unit is electrically connected to the output of the signal amplification and demodulation module. The data processing unit collects the amplified electrical signal and analyzes it to obtain the physical characteristics of the gas to be tested.

[0045] In one specific embodiment, refer to Figure 3 In this embodiment, a high-power LED with a center wavelength of approximately 450 nm is used as an incoherent fixed-spectrum light source, whose spectral width can cover the characteristic absorption peak of NO2 in the 400–500 nm range. The LED is intensity-modulated by a square-wave current output from a function generator, with a modulation depth of approximately 100% and a duty cycle of 50%, thereby producing a stable periodic light intensity change in the LED output. This broadband light is collimated and passes through an absorption cell, where it undergoes absorption with the gas, achieving broadband excitation of NO2.

[0046] Unlike using lasers, this embodiment does not require wavelength scanning and narrowband frequency stabilization control, which significantly reduces system complexity and cost, while avoiding optical noise caused by laser wavelength drift.

[0047] After broadband light is absorbed in a gas, the light energy is deposited periodically on the surface of a piezoelectric device according to a modulation rhythm, thereby inducing periodic temperature rises and thermoelastic stresses. These thermoelastic stresses act on the piezoelectric material, generating a time-varying piezoelectric charge signal. The piezoelectric charge is amplified by a preamplifier, and then a robust thermoelastic characteristic signal is extracted by a lock-in amplifier with a reference frequency from the function generator.

[0048] Reference Figure 4 The photothermal elastic response curves measured under pure N2 and 5% NO2 conditions are shown. The signal exhibits a clear square wave change, indicating that the incoherent fixed spectral excitation method proposed in this embodiment can stably generate photothermal elastic spectral signals.

[0049] In the experiment, the LED output power was set to 330mW. When alternating between pure N2 and 5% NO2, the signal-to-noise ratio (SNR) was measured to be approximately 3692. Further calculations revealed that the system's minimum detectable concentration (MDL) was approximately 13.5 ppm. This detection performance demonstrates that even without laser narrowband scanning and with an incoherent LED light source, this invention can still achieve highly sensitive detection of NO2 gas.

[0050] As can be seen from the above embodiments, the present invention utilizes an incoherent fixed-spectrum light source to achieve photothermoelastic excitation, which not only effectively avoids the problems of high cost, complex tuning, and strict alignment requirements of laser systems, but also enhances the stability and robustness of the photothermoelastic signal by utilizing the characteristic of broadband light covering the target absorption band. This solution has a simple structure, low cost, and is easy to integrate, and can be widely used in environmental monitoring, industrial emission detection, and portable gas analysis equipment.

[0051] Furthermore, refer to Figure 2 The present invention also proposes a control method for a photothermal elastic gas detection device based on incoherent fixed spectral excitation, which is applied to the aforementioned photothermal elastic gas detection device based on incoherent fixed spectral excitation. The control method for the photothermal elastic gas detection device based on incoherent fixed spectral excitation includes the following steps: Under the control of the data processing unit, the function generator of the S100 incoherent light source module outputs a periodic modulation signal. The driver converts the modulation signal into a stable current to drive the incoherent fixed spectrum light source, which then produces broadband light with a fixed spectrum. S200: The optical shaping module shapes the incoherent beam and effectively couples the incoherent light into the sampling module; S300, The gas to be tested in the gas-containing cavity absorbs the light energy of uncorrelated light; After the S400 broadband light is absorbed in the gas to be tested, the light energy is deposited on the sampling module in a periodic manner according to the modulation rhythm, thereby inducing periodic temperature rise and thermoelastic stress, generating a piezoelectric charge signal that varies with time. The S500 piezoelectric charge signal is amplified by the preamplifier of the signal amplification and demodulation module, and then the robust thermoelastic characteristic signal is extracted by the lock-in amplifier with reference to the function generator frequency and sent to the data processing unit for processing.

[0052] The above description is merely a preferred embodiment of the present invention. The present invention is not limited to the above-described embodiments. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this disclosure, as long as they achieve the technical effects of the present invention by the same means, should be included within the scope of protection of this disclosure and should fall within the protection scope of the present invention. Within the protection scope of the present invention, the technical solutions and / or implementation methods can have various modifications and variations.

Claims

1. A photothermal elastic gas detection device based on incoherent fixed spectral excitation, characterized in that, The aforementioned photothermal elastic gas detection device based on incoherent fixed spectral excitation comprises, in sequence: Incoherent light source module, used to generate incoherent light with controllable power and intensity modulation depth; An optical shaping module is used to shape incoherent beams and effectively couple incoherent light into the sampling module; A gas absorption module is provided with a gas container cavity for storing the gas to be tested. Uncorrelated light that has been shaped is incident on the gas container cavity, and the gas to be tested, which is pre-placed in the gas container cavity, absorbs the light energy of the uncorrelated light. The sampling module is used to collect the thermoelastic stress generated by the periodic thermal deposition of uncorrelated light after absorption by the gas under test, and convert it into an electrical signal. The signal amplification and demodulation module is used to extract, amplify, and demodulate the electrical signal acquired by the sampling module.

2. The photothermal elastic gas detection device based on incoherent fixed spectral excitation according to claim 1, characterized in that, The uncorrelated light source module includes a function generator, a driver, and an incoherent fixed-spectrum light source connected in sequence. The function generator is used to output a periodic modulation signal, and the driver converts the modulation signal output by the function generator into a stable current to drive an incoherent fixed-spectrum light source. The incoherent fixed-spectrum light source generates broadband light with a fixed spectrum under the drive of the current output by the driver.

3. The photothermal elastic gas detection device based on incoherent fixed spectral excitation according to claim 2, characterized in that, The incoherent fixed-spectrum light source is a broadband LED or a superluminescent diode (SLED).

4. The photothermal elastic gas detection device based on incoherent fixed spectral excitation according to claim 1, characterized in that, The optical shaping module includes a collimating lens or an optical collimation system.

5. The photothermal elastic gas detection device based on incoherent fixed spectral excitation according to claim 1, characterized in that, The gas-containing cavity of the gas absorption module is either a gas absorption pool or an open sampling area. The gas absorption cell or the open sampling area contains the gas to be measured.

6. The photothermal elastic gas detection device based on incoherent fixed spectral excitation according to claim 1, characterized in that, The sampling module is a photothermal detector or a pyroelectric detector.

7. The photothermal elastic gas detection device based on incoherent fixed spectral excitation according to claim 1, characterized in that, The sampling module is a piezoelectric tuning fork, which receives thermoelastic stress and converts it into an electrical signal.

8. The photothermal elastic gas detection device based on incoherent fixed spectral excitation according to claim 1, characterized in that, The signal amplification and demodulation module includes a preamplifier and a lock-in amplifier.

9. The photothermal elastic gas detection device based on incoherent fixed spectral excitation according to claim 1, characterized in that, It also includes a data processing unit, which is used to control the process of the photothermal elastic gas detection device based on incoherent fixed spectral excitation and the output data of the acquisition signal amplification and demodulation module. The output of the data processing unit is connected to the input of the function generator of the unrelated light source module, and the data processing unit is used to control the output of the function generator; The input terminal of the data processing unit is electrically connected to the output of the signal amplification and demodulation module. The data processing unit collects the amplified electrical signal and analyzes it to obtain the physical characteristics of the gas to be tested.

10. A control method for a photothermal elastic gas detection device based on incoherent fixed spectral excitation, applied to the photothermal elastic gas detection device based on incoherent fixed spectral excitation as described in any one of claims 1 to 9, characterized in that, The control method for the photothermal elastic gas detection device based on incoherent fixed spectral excitation includes the following steps: Under the control of the data processing unit, the function generator of the S100 incoherent light source module outputs a periodic modulation signal. The driver converts the modulation signal into a stable current to drive the incoherent fixed spectrum light source, which then produces broadband light with a fixed spectrum. S200: The optical shaping module shapes the incoherent beam and effectively couples the incoherent light into the sampling module; S300, The gas to be tested in the gas-containing cavity absorbs the light energy of uncorrelated light; After the S400 broadband light is absorbed in the gas to be tested, the light energy is deposited on the sampling module in a periodic manner according to the modulation rhythm, thereby inducing periodic temperature rise and thermoelastic stress, generating a piezoelectric charge signal that varies with time. The S500 piezoelectric charge signal is amplified by the preamplifier of the signal amplification and demodulation module, and then the robust thermoelastic characteristic signal is extracted by the lock-in amplifier with reference to the function generator frequency and sent to the data processing unit for processing.

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