CN118090667A - Shutdown-free detection and control method and system suitable for continuous wave cavity ring-down spectroscopy - Google Patents
Shutdown-free detection and control method and system suitable for continuous wave cavity ring-down spectroscopy Download PDFInfo
- Publication number
- CN118090667A CN118090667A CN202410413864.XA CN202410413864A CN118090667A CN 118090667 A CN118090667 A CN 118090667A CN 202410413864 A CN202410413864 A CN 202410413864A CN 118090667 A CN118090667 A CN 118090667A
- Authority
- CN
- China
- Prior art keywords
- laser light
- cavity
- light source
- information
- optical
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Granted
Links
Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
- G01N21/17—Systems in which incident light is modified in accordance with the properties of the material investigated
- G01N21/25—Colour; Spectral properties, i.e. comparison of effect of material on the light at two or more different wavelengths or wavelength bands
- G01N21/31—Investigating relative effect of material at wavelengths characteristic of specific elements or molecules, e.g. atomic absorption spectrometry
- G01N21/39—Investigating relative effect of material at wavelengths characteristic of specific elements or molecules, e.g. atomic absorption spectrometry using tunable lasers
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
- G01N21/01—Arrangements or apparatus for facilitating the optical investigation
Landscapes
- Physics & Mathematics (AREA)
- General Health & Medical Sciences (AREA)
- Life Sciences & Earth Sciences (AREA)
- Chemical & Material Sciences (AREA)
- Analytical Chemistry (AREA)
- Biochemistry (AREA)
- Health & Medical Sciences (AREA)
- General Physics & Mathematics (AREA)
- Immunology (AREA)
- Pathology (AREA)
- Spectroscopy & Molecular Physics (AREA)
- Optics & Photonics (AREA)
- Investigating Or Analysing Materials By Optical Means (AREA)
Abstract
本发明涉及一种适于连续波腔衰荡光谱的免关断检测调控方法及系统。其包括：对激光光源调控时，包括依次进行的一次调制步骤以及二次调制步骤，执行对激光光源的一次调制步骤后，使得目标气体在F‑P光学谐振腔单元内处于单腔模谐振；执行对激光光源的二次调制步骤时，基于目标气体在单腔模谐振下的光功率衰减状态，生成所述激光光源的波长调制补偿信息；基于所述波长调制补偿信息调控激光光源所发射激光的波长，以使得当前波长的激光入射至F‑P光学谐振腔单元后，与所述F‑P光学谐振腔单元间不发生新的模式匹配。本发明可避免光路的关断，降低基于连续波腔衰荡光谱下对痕迹气体检测的复杂度以及成本。
The present invention relates to a shutdown-free detection and control method and system suitable for continuous wave cavity ring-down spectroscopy. It comprises: when regulating a laser light source, it comprises a primary modulation step and a secondary modulation step which are performed in sequence, and after performing the primary modulation step of the laser light source, the target gas is in single-cavity mode resonance in an F-P optical resonant cavity unit; when performing the secondary modulation step of the laser light source, based on the optical power attenuation state of the target gas under single-cavity mode resonance, wavelength modulation compensation information of the laser light source is generated; based on the wavelength modulation compensation information, the wavelength of the laser emitted by the laser light source is regulated, so that after the laser light of the current wavelength is incident on the F-P optical resonant cavity unit, no new mode matching occurs between the laser light and the F-P optical resonant cavity unit. The present invention can avoid the shutdown of the optical path and reduce the complexity and cost of trace gas detection based on continuous wave cavity ring-down spectroscopy.
Description
Technical Field
The invention relates to a turn-off-free detection regulation method and system, in particular to a turn-off-free detection regulation method and system suitable for continuous wave cavity ring-down spectroscopy.
Background
Cavity ring-down spectroscopy based on gas absorption spectrum characteristics has been well applied in the field of trace gas detection; however, conventional continuous wave cavity ring-down spectroscopy techniques generally require a fast shut-down of the optical path when the laser intensity in the cavity reaches a threshold in order to ensure the generation of a cavity ring-down event. Currently, when the optical path is turned off, an acousto-optic modulator or an electro-optic modulator is generally required.
As can be seen from the above description, when the cavity ring-down spectroscopy is used for detecting the gas, the complexity and cost of detecting the gas are increased due to the need of shutting off the optical path, which limits the application of detecting trace gas.
Disclosure of Invention
The invention aims to overcome the defects in the prior art and provide a turn-off-free detection regulation method and system suitable for continuous wave cavity ring-down spectroscopy, which can avoid turn-off of an optical path when trace gas is detected based on the continuous wave cavity ring-down spectroscopy, and reduce the complexity and cost of trace gas detection based on the continuous wave cavity ring-down spectroscopy.
According to the technical scheme provided by the invention, the turn-off-free detection and regulation method suitable for continuous wave cavity ring-down spectroscopy comprises the following steps:
Providing a continuous wave cavity ring-down spectroscopy device for detecting trace gas, wherein the continuous wave cavity ring-down spectroscopy device at least comprises a laser light source and an F-P optical resonant cavity unit, and laser energy emitted by the laser light source is incident to the F-P optical resonant cavity unit;
Regulating and controlling the working state of the laser light source to enable the laser light source to be always in an off-free state when detecting the target gas introduced into the F-P optical resonant cavity unit, wherein the regulating and controlling the laser light source comprises a primary modulation step and a secondary modulation step which are sequentially carried out,
After the primary modulation step of the laser light source is carried out, the target gas is made to resonate in Shan Qiangmo in the F-P optical resonant cavity unit;
When the secondary modulation step of the laser light source is executed, generating wavelength modulation compensation information of the laser light source based on the optical power attenuation state of the target gas under single-cavity mode resonance;
and regulating and controlling the wavelength of laser emitted by the laser source based on the wavelength modulation compensation information, so that no new mode matching occurs between the laser with the current wavelength and the F-P optical resonant cavity unit after the laser with the current wavelength is incident to the F-P optical resonant cavity unit.
When the primary modulation step of the laser light source is executed, the method comprises the following steps:
according to the target gas, selecting initial working parameters of a laser light source, wherein the initial working parameters comprise initial reference current, initial temperature and the central wavelength of emitted laser;
Configuring primary modulation parameters used for primary modulation of a laser light source, wherein the configured primary modulation parameters comprise a temperature modulation step length for regulating and controlling the temperature of the laser light source and/or a triangular wave current primary modulation parameter for modulating the current of the laser light source, and the triangular wave current primary modulation parameter comprises a triangular wave current primary modulation frequency and a triangular wave current primary modulation amplitude;
Starting a laser source according to initial working parameters, modulating the laser source according to primary modulation parameters, and after each modulation, making the generated laser incident into the F-P optical resonant cavity unit;
After laser is incident to the F-P optical resonant cavity unit, optical cavity optical mode identification is carried out on the F-P optical resonant cavity unit, and if the currently identified optical cavity optical mode is non-single cavity mode resonance, the laser light source is continuously modulated based on primary modulation parameters until the currently identified optical cavity optical mode is single cavity mode resonance.
When the modulation frequency and the modulation amplitude in the primary modulation parameter are configured, the method comprises the following steps:
Picking up the resonant cavity characteristic parameters of the F-P optical resonant cavity unit, and calculating the free spectral width FSR of the optical cavity based on the picked resonant cavity characteristic parameters;
Based on the free spectrum width FSR of the optical cavity, configuring a temperature modulation step length, a primary modulation frequency of the triangular wave current and a primary modulation amplitude of the triangular wave current.
The step of performing secondary modulation on the laser light source and generating wavelength modulation compensation information includes:
Generating stability criterion information based on an optical power attenuation state of the target gas under single-cavity mode resonance, wherein the stability criterion information comprises effective ring-down event quantity information, quick scanning frequency information and ring-down signal quality information;
and when the continuous wave cavity ring-down spectroscopy device is judged to be in an unstable detection state for the target gas based on the stability criterion information, generating wavelength modulation compensation information based on the stability criterion information.
When generating the stability criterion information, the method comprises the following steps:
generating a preliminary criterion of stability based on the optical power attenuation state of the target gas under single-cavity mode resonance;
performing sign extraction and generating mode identification decision information based on the optical power attenuation state of the target gas under single-cavity mode resonance, and adjusting the generated stability preliminary criterion, wherein,
After the feature extraction, obtaining gas detection modulation feature information, wherein the gas detection modulation feature information comprises a light cavity transverse mode feature, a light cavity longitudinal mode feature, a line width feature of a laser light source, an environment feature and a noise level feature;
And adjusting the generated stability preliminary criterion information based on the gas detection modulation characteristic information and the mode identification decision information to generate stability criterion information.
The continuous wave cavity ring down spectroscopy apparatus further comprises a photodetector, wherein,
Detecting the optical signal transmitted out of the F-P optical resonant cavity unit by utilizing a photoelectric detector to obtain optical signal detection information after detection, wherein the optical signal detection information comprises the shape of a light spot and light intensity information;
based on the optical signal detection information, pattern recognition decision information is generated.
When the generated stability preliminary criterion is adjusted based on the optical cavity transverse mode characteristics, the method comprises the following steps:
When the optical cavity transverse mode is characterized as the fundamental mode and the higher order mode rejection ratio is at least 100: and 1, continuously identifying the effective ring-down events, otherwise, setting the number of the identified effective ring-down events to zero, and regenerating a stability preliminary criterion.
When the stable state detection of the continuous wave cavity ring-down spectroscopy device to the target gas is judged based on the stability criterion information, the method comprises the following steps:
and when the cavity mode matching efficiency is not lower than 0.5 and the ring-down signal fitting degree is not lower than 0.9, judging that the cavity mode matching efficiency is in a stable state, otherwise, judging that the cavity mode matching efficiency is in an unstable state.
When generating wavelength modulation compensation information based on the stability criterion information, the method comprises the following steps:
constructing a wavelength modulation compensation model based on a BP neural network;
Based on the stability criterion information, the wavelength modulation compensation model generates wavelength modulation compensation information.
The turn-off-free detection regulation and control system suitable for the continuous wave cavity ring-down spectrum comprises a turn-off-free detection regulation and control processor, wherein the turn-off-free detection regulation and control processor is used for performing turn-off-free detection regulation and control on a laser light source in a continuous wave cavity ring-down spectrum device based on the method so as to control the laser light source to be in a turn-off-free state to detect target gas.
The invention has the advantages that: when the laser light source is regulated and controlled, the method comprises a primary modulation step and a secondary modulation step which are sequentially carried out, and after the primary modulation step of the laser light source is carried out, the target gas is made to be at Shan Qiangmo resonance in the F-P optical resonant cavity unit; when the secondary modulation step of the laser light source is executed, generating wavelength modulation compensation information of the laser light source based on the optical power attenuation state of the target gas under single-cavity mode resonance; and regulating and controlling the wavelength of laser emitted by the laser source based on the wavelength modulation compensation information, so that after the laser with the current wavelength is incident to the F-P optical resonant cavity unit, no new mode matching is generated between the laser and the F-P optical resonant cavity unit, and therefore, when trace gas is detected based on the continuous wave cavity ring-down spectrum, in order to avoid the turn-off of an optical path, the complexity and the cost of trace gas detection based on the continuous wave cavity ring-down spectrum are reduced.
Drawings
FIG. 1 is a flow chart illustrating an embodiment of the present invention for implementing turn-off-free detection regulation.
Detailed Description
The invention will be further described with reference to the following specific drawings and examples.
In order to avoid the turn-off of the optical path when detecting trace gas based on the continuous wave cavity ring-down spectrum, and reduce the complexity and cost of trace gas detection based on the continuous wave cavity ring-down spectrum, the turn-off-free detection regulation method suitable for the continuous wave cavity ring-down spectrum according to one embodiment of the invention comprises the following steps:
Providing a continuous wave cavity ring-down spectroscopy device for detecting trace gas, wherein the continuous wave cavity ring-down spectroscopy device at least comprises a laser light source and an F-P optical resonant cavity unit, and laser energy emitted by the laser light source is incident to the F-P optical resonant cavity unit;
Regulating and controlling the working state of the laser light source to enable the laser light source to be always in an off-free state when detecting the target gas introduced into the F-P optical resonant cavity unit, wherein the regulating and controlling the laser light source comprises a primary modulation step and a secondary modulation step which are sequentially carried out,
After the primary modulation step of the laser light source is carried out, the target gas is made to resonate in Shan Qiangmo in the F-P optical resonant cavity unit;
When the secondary modulation step of the laser light source is executed, generating wavelength modulation compensation information of the laser light source based on the optical power attenuation state of the target gas under single-cavity mode resonance;
and regulating and controlling the wavelength of laser emitted by the laser source based on the wavelength modulation compensation information, so that no new mode matching occurs between the laser with the current wavelength and the F-P optical resonant cavity unit after the laser with the current wavelength is incident to the F-P optical resonant cavity unit.
As can be seen from the foregoing, in detecting trace gas, it is generally desirable to use a continuous wave cavity ring-down spectroscopy apparatus, which may take the form of a conventional system, e.g., a continuous wave cavity ring-down spectroscopy apparatus may include a laser source for generating laser light to be applied to the F-P optical resonator unit, and an F-P optical resonator unit, which may take the form of a conventional system, and a DFB laser which may preferably take the form of a DFB laser due to its small size, high stability, and small frequency range modulation characteristics, and a photodetector for detecting light transmitted through the F-P optical resonator unit.
In specific implementation, the F-P optical resonant cavity unit can adopt the existing common form, generally, the F-P optical resonant cavity unit can be composed of high-reflectivity mirrors (reflectivity is higher than 99.99%) which are strictly placed on two sides, the outer layer of the F-P optical resonant cavity unit is fixed by quartz glass with ultralow expansion coefficient to form a closed gas cavity, and target gas can be introduced into the F-P optical resonant cavity unit. Due to the cavity mode matching characteristics of the F-P optical resonant cavity unit itself, only laser light of a specific frequency is allowed to pass within the optical cavity and power is accumulated. The photoelectric detector can be used for detecting the light transmitted out of the F-P optical resonant cavity unit so as to generate optical signal detection information after detection, wherein the optical signal detection information comprises light spot information and light intensity information; the photoelectric detector can adopt the existing common form, and the mode of detecting the light penetrating out of the F-P optical resonant cavity unit by using the photoelectric detector can be consistent with the existing mode, so that the detection information of the optical signal can be obtained by detection, and the details are not repeated here.
As can be seen from the above description, in the prior art, when the intensity of the laser in the cavity of the F-P optical resonator unit reaches the power threshold, the optical path is generally required to be turned off rapidly, that is, the laser source is required to be turned off, so as to avoid the incident laser from interfering with the ring-down signal existing in the F-P optical resonator unit, where the power threshold of the intensity of the laser in the cavity can be generally set according to the detection requirement of the trace gas, so as to meet the requirement of trace gas detection. The turn-off-free detection regulation method in the invention specifically refers to the method capable of avoiding turn-off of the laser light source and turn-off control of the laser light source when detecting the target gas, and at this time, capable of reducing complexity and cost when detecting the target gas. The target gas is generally the trace gas which is common and can be detected by using the continuous wave cavity ring-down spectroscopy device, and the type of the target gas is selected according to the needs so as to meet the detection needs of the gas.
The laser light source is always in an off-free state, namely the laser light source is in a working state in the process of detecting the target gas, and at the moment, the laser light source can continuously generate laser which is incident into the F-P optical resonant cavity unit. In order to meet the requirement of detecting the target gas and avoid controlling the laser light source to turn off, fig. 1 shows a flowchart of an embodiment of adjusting and controlling the laser light source, in which a primary modulation step and a secondary modulation step are sequentially performed on the laser light source, that is, after the two modulation steps, the laser light source can continuously detect the target gas under the condition of non-turn-off.
In the implementation, after the primary modulation step of the laser light source is executed, the target gas is made to resonate in the F-P optical resonant cavity unit at Shan Qiangmo; from the above description, it is known that a resonant cavity, i.e. an F-P optical cavity, can be provided by means of an F-P optical resonant cavity unit, wherein the F-P optical cavity, i.e. a Fabry-perot optical cavity, is an optical resonant cavity consisting of two parallel mirrors. Single-cavity mode resonance is an important characteristic of F-P optical cavities that describes that under certain conditions, only one stable resonant mode exists within the F-P optical cavity. In the F-P optical cavity, when light waves are reflected back and forth between two mirrors, light waves of certain specific wavelengths are reinforced due to interference phenomena of light, and a resonance effect is formed. This resonance effect results in only one stable resonant mode within the F-P optical cavity, i.e., single cavity mode resonance.
For single cavity mode resonance, it means that the optical wave energy in the F-P optical cavity can concentrate on a stable mode at a specific wavelength or frequency to form a sharp peak, and the single cavity mode resonance has high stability and repeatability, and the laser output power can be enhanced by utilizing the characteristic of the single cavity mode resonance, even under the output power of the milliwatt level of the DFB laser, the light transmitted through the resonant cavity can have a proper signal-to-noise ratio, and can be effectively detected by a photoelectric detector.
In specific implementation, the existing common technical means can be adopted to judge whether the F-P optical cavity is in single-cavity mode resonance, for example, by observing the position of a spectrum resonance peak of light transmitted through the resonant cavity, if the spectrum resonance peak is stable in a certain time, the F-P optical resonant cavity unit is considered to be in single-mode resonance, namely, after one-time modulation, the whole F-P optical resonant cavity unit is kept to work for a certain time, and whether an output spectrum resonance peak is stable is observed. Of course, it is also possible to determine whether the target gas is at Shan Qiangmo resonance in the F-P optical resonator unit after one modulation, and the specific determination technique may be selected according to the need, which is not illustrated here.
After the primary modulation step is performed, that is, after the target gas is in Shan Qiang-mode resonance in the F-P optical resonant cavity unit, the secondary modulation step for the laser light source is performed. And when the secondary modulation step is executed, generating wavelength modulation compensation information of the laser light source, and regulating and controlling the wavelength of laser generated by the laser light source based on the wavelength modulation compensation information, namely realizing the frequency of light waves of the laser incident into the F-P optical resonant cavity unit. Specifically, the main purpose of regulating the wavelength of the laser is to avoid new mode matching between the laser and the F-P optical resonant cavity unit after the laser is incident into the F-P optical resonant cavity unit, that is, after the laser wavelength is regulated, the laser is incident into the F-P optical resonant cavity unit, and then the new mode matching cannot occur.
When new modes are matched, ring-down signals generated by at least two times of matching are generally generated in the F-P optical resonant cavity unit, and the ring-down signals generated by the two times of matching are mutually interfered to influence the detection of target gas; wherein, the first mode matching is that the target gas is in Shan Qiang mode resonance in the F-P optical resonant cavity unit. It should be noted that the characteristic of pattern matching is that the rapid accumulation of optical power in the resonant cavity exceeds the power threshold, the voltage detected and output by the photodetector reflects the laser power in the F-P optical cavity at any time, and by comparing the output voltage of the photodetector with the threshold voltage, it can be determined whether a new pattern matching occurs in the resonant cavity, where the threshold voltage corresponds to the power threshold one by one, and the power threshold can refer to the above description, that is, the power threshold can be reflected by the threshold voltage.
It will be appreciated that when the target gas is at Shan Qiang mode resonance in the F-P optical resonator unit, the laser power detected by the photodetector will also exceed the power threshold, i.e. by monitoring the laser power above the power threshold, it can be determined whether it is at single mode resonance.
In one embodiment of the present invention, the step of performing a primary modulation of the laser source includes:
according to the target gas, selecting initial working parameters of a laser light source, wherein the initial working parameters comprise initial reference current, initial temperature and the central wavelength of emitted laser;
Configuring primary modulation parameters used for primary modulation of a laser light source, wherein the configured primary modulation parameters comprise a temperature modulation step length for regulating and controlling the temperature of the laser light source and/or a triangular wave current primary modulation parameter for modulating the current of the laser light source, and the triangular wave current primary modulation parameter comprises a triangular wave current primary modulation frequency and a triangular wave current primary modulation amplitude;
Starting a laser source according to initial working parameters, modulating the laser source according to primary modulation parameters, and after each modulation, making the generated laser incident into the F-P optical resonant cavity unit;
After laser is incident to the F-P optical resonant cavity unit, optical cavity optical mode identification is carried out on the F-P optical resonant cavity unit, and if the currently identified optical cavity optical mode is non-single cavity mode resonance, the laser light source is continuously modulated based on primary modulation parameters until the currently identified optical cavity optical mode is single cavity mode resonance.
As can be seen from the above description, for any determined target gas, the absorption spectrum characteristic of the target gas may be determined, for example, the absorption spectrum characteristic of the target gas may be determined by querying the absorption spectrum characteristic parameter of the target gas in the HITRAN database, and the specific manner of obtaining the absorption spectrum characteristic of the target gas may be selected according to need.
After the absorption spectrum characteristics of the target gas are determined, configuring initial working parameters of a laser light source, wherein the initial working parameters comprise initial reference current, initial temperature and the central wavelength of the emitted laser, and the central wavelength of the emitted laser is required to correspond to the gas absorption spectrum characteristics of the target gas; specifically, the central wavelength of the emitted laser light needs to correspond to the gas absorption spectrum characteristic of the target gas, which means that the central wavelength of the emitted laser light is consistent with the molecular absorption spectrum wavelength of the target gas, that is, the emitted laser light can be absorbed by the target gas.
After the initial operating parameters are determined, primary modulation parameters need to be configured, that is, primary modulation of the laser source can be performed according to the primary modulation parameters. The wavelength of the laser emitted by the laser light source is determined by the driving current and the temperature of the laser light source, the current and the temperature of the laser light source are modulated, and under the condition of the laser light source which is not turned off, the mode matching of the optical cavity and the laser is realized and a ring-down event is generated. Therefore, similar to the existing modulation of the laser light source, the primary modulation of the laser light source comprises temperature modulation of the laser light source and/or current modulation of the laser light source, wherein the current modulation of the laser light source, particularly, the loading of a modulation current to the laser light source, is carried out, in one embodiment of the invention, the modulation current loaded to the laser light source preferably adopts triangular wave current, particularly, when the triangular wave current is adopted to carry out current modulation on the laser light source, particularly, the loading of a triangular wave current on the control current of the laser light source is carried out, the driving current of the laser light source can be adjusted based on the loaded triangular wave current, and the wavelength, namely, the output light power of the laser light source, of the laser light is further adjusted. The following will specifically describe an example of the modulation current using a triangular wave current.
When the method is implemented, the temperature modulation step length is included when the laser light source is subjected to temperature modulation; when the triangular wave current is used for carrying out current modulation on the laser light source, the primary modulation parameters of the triangular wave current comprise primary modulation frequency of the triangular wave current and primary modulation amplitude of the triangular wave current, and the configuration mode of the primary modulation parameters is described below.
In one embodiment of the present invention, when configuring the modulation frequency and the modulation amplitude in the primary modulation parameter, the method includes:
Picking up the resonant cavity characteristic parameters of the F-P optical resonant cavity unit, and calculating the free spectral width FSR of the optical cavity based on the picked resonant cavity characteristic parameters;
Based on the free spectrum width FSR of the optical cavity, configuring a temperature modulation step length, a primary modulation frequency of the triangular wave current and a primary modulation amplitude of the triangular wave current.
It should be noted that, for an F-P optical resonator unit, when a beam of laser enters, only a few of the laser is transmitted, and most of the rest of the laser is reflected by the F-P optical resonator unit for tens or hundreds of times, and the phase of the laser is deviated from the original laser after reflection; most lasers produce superposition and cancellation of waveforms after multiple reflections, resulting in failure to accumulate in the F-P optical resonator element.
In order to enable the laser to form a standing wave in the F-P optical resonator unit and accumulate its power in the F-P optical resonator unit, it is therefore necessary to precisely adjust the wavelength of the laser light output from the laser light source so that there is an integer multiple of the half-wave of the laser light equal to the cavity length of the F-P optical resonator unit.
Therefore, the resonant cavity characteristic parameters of the F-P optical resonant cavity unit are picked up, and the free spectral width FSR of the optical cavity is calculated, wherein the picked resonant cavity characteristic parameters specifically refer to the cavity length of the resonant cavity in the F-P optical resonant cavity unit, and the cavity length of the resonant cavity determines the free spectral width FSR of the optical cavity, and specifically comprise the following steps: FSR = speed of light/(2 x cavity length), the free spectral width of the cavity FSR represents the frequency spacing of adjacent longitudinal modes within the F-P optical resonator element.
When the triangular wave current modulation is adopted, the current frequency of the triangular wave can influence the size of the optical power output by the laser light source, when the frequency of the triangular wave current is too high, the power threshold cannot be reached possibly, at the moment, the frequency of the triangular wave current needs to be reduced, when the frequency of the triangular wave current is too low, the pattern matching efficiency is reduced, and the frequency of the triangular wave current needs to be improved, so that the frequency of the triangular wave current can be fixed to be 1KHz during primary modulation, namely, the primary modulation frequency of the triangular wave current is 1KHz and remains unchanged during primary modulation, namely, the frequency of the triangular wave current loaded onto the laser light source is 1KHz.
The primary modulation amplitude of the triangular wave current can be set to 1/8FSR. The temperature of the preset laser light source is modulated by a small step length, and the temperature modulation step length is initially set as FSR, namely the temperature modulation step length can be set as the free spectrum width FSR of the optical cavity. When the temperature of the laser light source is modulated, the temperature of the laser light source is increased or decreased by one temperature modulation step each time, namely, the working temperature of the laser light source is increased or decreased by FSR each time when the temperature is modulated once. When the triangular wave current is used for carrying out current modulation on the laser light source, the frequency of the triangular wave current is kept to be 1KHz, and the amplitude of the triangular wave current is increased or reduced by one triangular wave once current modulation amplitude each time, namely, the amplitude of the triangular wave current is increased or reduced by 1/8FSR each time.
In specific implementation, the laser light source is started based on the selected initial working parameters, the laser light source is modulated according to the configured disposable modulation parameters, the optical mode in the F-P optical resonant cavity unit is required to be identified after each modulation, if the identified optical mode is not single-cavity mode resonance, the laser light source is required to be modulated again, for example, the mode of increasing/decreasing amplitude is carried out at least based on the primary modulation amplitude of the triangular wave current, and then the process of identifying the optical mode in the F-P optical resonant cavity unit based on the disposable modulation parameters is repeated until the optical mode in the F-P optical resonant cavity unit is identified as single-cavity mode resonance.
In one embodiment of the present invention, when the primary modulation step is performed, the primary modulation step is generally performed based on both the temperature modulation step and the primary modulation amplitude of the triangular wave current, where the primary modulation amplitude of the triangular wave current is used to control the cavity mode matching, and if cavity mode matching cannot be formed in the cavity, the primary modulation amplitude of the triangular wave current is required to be increased based on the primary modulation amplitude of the triangular wave current until resonance is formed in the F-P optical resonant cavity unit. When modulating the laser light source based on the temperature modulation step length, theoretically, one single-cavity mode resonance exists at the temperature corresponding to one FSR at each time of modulation, but if the single-cavity mode resonance is not detected, that is, no effective single-cavity mode resonance is detected at each step length, the temperature of the laser light source needs to be increased or decreased based on the temperature modulation step length.
Therefore, the laser light source is modulated according to the primary modulation parameters, and the temperature of the laser light source and/or the amplitude of the triangular wave current can be respectively adjusted according to the state in the F-P optical resonant cavity unit until the identified optical cavity optical mode can be satisfied as single cavity mode resonance.
In one embodiment of the present invention, the step of performing secondary modulation on the laser light source and generating wavelength modulation compensation information includes:
Generating stability criterion information based on an optical power attenuation state of the target gas under single-cavity mode resonance, wherein the stability criterion information comprises effective ring-down event quantity information, quick scanning frequency information and ring-down signal quality information;
and when the continuous wave cavity ring-down spectroscopy device is judged to be in an unstable detection state for the target gas based on the stability criterion information, generating wavelength modulation compensation information based on the stability criterion information.
Specifically, the fast scan frequency information refers to current frequency of triangular wave current when the triangular wave current is used for current modulation of the laser light source, and the fast scan frequency information is related to cavity mode matching efficiency information, wherein the cavity mode matching efficiency is a ratio of the number of detected effective ring-down events to 2 times of the triangular wave current frequency within 1s, and the meaning is probability of occurrence of the effective ring-down events on one rising edge or one falling edge of the triangular wave current. The ring down signal quality, i.e., the negative exponential fitness of the ring down signal, generally needs to be higher than 0.
The number of effective ring-down events information specifically includes the number of effective ring-down events, i.e. the number of effective ring-down events occurring in one second, and generally, the effective ring-down events are defined as ring-down events with the initial value of the detected ring-down signal higher than the threshold voltage. The ring-down signal is specifically a digital signal obtained by photoelectrically converting and AD-converting an optical signal detected by a photodetector, that is, the ring-down signal corresponds to the optical signal detected by the photodetector.
In specific implementation, the resonant signals of the light rays transmitted by the resonant cavity can be detected through the photoelectric detector, namely, the resonant signals detected by the photoelectric detector are counted based on the light signals detected by the photoelectric detector, and the cavity mode matching efficiency is calculated by counting the number of the resonant signals within 1 second and comparing the frequency of the triangular wave current. When counting resonance signals, the light transmitted by the resonant cavity is detected by the photoelectric detector, and the light is considered as an effective resonance signal. Specifically, the resonance signal detected by the photodetector is the optical power attenuation state under the single-cavity mode resonance based on the target gas, namely the optical power attenuation state under the single-cavity mode resonance can be obtained based on the light spot information of the transmitted light and the light intensity signal.
In addition, the calculation of the negative index fitting degree of the ring-down signal generated by the photoelectric detector can be realized through a strong Wen Boge Marquard fitting algorithm, and of course, the negative index fitting degree of the ring-down signal can also be determined in other modes, and the specific mode can be selected according to the requirement so as to obtain the negative index fitting degree of the ring-down signal.
In fig. 1, when it is determined that the laser light source is in a stable detection state, the laser light source is locked, that is, the laser light source is kept operating under the current parameters, and thereafter, turn-off-free detection of the target gas can be achieved by using the laser light source. The current parameters specifically refer to setting the temperature of the laser light source based on primary modulation, and setting the frequency of the triangular wave current and the amplitude of the triangular wave current based on secondary modulation.
In one embodiment of the present invention, when generating stability criterion information, the method includes:
Generating mode identification decision information based on an optical power attenuation state of target gas under single-cavity mode resonance, and generating quick scanning frequency information in a stability preliminary criterion based on the mode identification decision information;
performing sign extraction based on an optical power attenuation state of the target gas under single-cavity mode resonance to obtain gas detection modulation characteristic information, wherein,
After the feature extraction, obtaining gas detection modulation feature information, wherein the gas detection modulation feature information comprises a light cavity transverse mode feature, a light cavity longitudinal mode feature, a line width feature of a laser light source, an environment feature and a noise level feature;
based on the gas detection modulation characteristic information, identifying and adjusting the generated effective ring-down event quantity information and ring-down signal quality information in the stability preliminary criterion so as to generate stability criterion information after identifying and adjusting.
In particular embodiments, the preliminary criteria for stability include effective ring-down event number information, fast scan frequency information, and ring-down signal quality information. The effective ring-down event number information and ring-down signal quality information of the stability preliminary criteria can be generated by adopting the above description. The fast scan frequency information may be generated based on mode decision information, and one possible scheme is: the mode identification decision information is directly read to generate the frequency of the resonance signal detected by the photoelectric detector, as shown in fig. 1, the frequency of the detected resonance signal is determined by the frequency of the control current of the laser light source superimposed with the triangular wave current, so that the rapid scanning frequency information can be correspondingly obtained by adopting the technical means commonly used in the technical field.
For the fast scan frequency information, one possible generation method is: continuously monitoring and recording optical signals escaping from the F-P optical resonant cavity unit by using a photoelectric detector, and converting the detected optical signals into electric signals and digital signals; identifying resonance signals of the converted digital signals by utilizing a Fourier transform or similar frequency spectrum analysis method to find out resonance components corresponding to the laser pulse frequency, and then counting the number of the identified resonance signals; and then the rapid scanning frequency information can be generated and obtained by calculating the peak value number and the duration time of the resonance signals.
In order to improve the accuracy and reliability of generating the stability criterion, in one embodiment of the present invention, the stability preliminary criterion may be adjusted based on the gas detection modulation characteristic information and the pattern recognition decision information, so as to generate the required stability criterion information after adjustment.
As can be seen from the above description, the light transmitted by the resonant cavity can be detected by the photodetector, that is, the photodetector can be used to perform optical signal detection, and after the detection, the spot information and the light intensity information of the transmitted light are determined, where the spot information includes the spot shape, and then the corresponding transverse mode characteristic and longitudinal mode characteristic of the optical cavity can be extracted based on the spot shape and the signal intensity.
In specific implementation, the line width characteristics of the laser light source can be extracted by inquiring a data manual of the laser light source and the like. For the environmental characteristics, the current temperature information and the air pressure information are specifically referred to, wherein the temperature information can be obtained by setting a temperature sensor mode, the air pressure information can be obtained by setting an air pressure sensor mode, and of course, the temperature information and the air pressure information of the environmental characteristics can also be obtained by adopting other modes, and the specific obtaining mode can be selected according to the needs so as to meet the actual needs.
For noise level characteristics, in one embodiment of the present invention, FFT (Fast Fourier Transform) transforms are performed on optical signal detection information based on the detection of the photodetector to convert from the time domain to the frequency domain; in the frequency domain, the signal is decomposed into a series of sine waves of different frequencies, where the high frequency characteristic generally corresponds to a higher frequency component. By analyzing the frequency domain information after FFT, the corresponding high frequency characteristics can be identified. At this time, the high frequency characteristic is regarded as noise, that is, a noise level characteristic is obtained. In the implementation, after the noise level characteristic is obtained, a low-pass filtering mode can be adopted to filter out the high-frequency characteristic, and the filtered frequency domain signal is subjected to inverse FFT conversion and is converted back to the time domain.
According to the characteristic selection process, the optical cavity transverse mode characteristic, the optical cavity longitudinal mode characteristic, the line width characteristic, the environment characteristic and the noise level characteristic of the laser light source are taken as main characteristic quantities, the characteristic dimension reduction is realized, other irrelevant variables are eliminated, the main component after dimension reduction is taken as an input layer of secondary modulation, and an optical cavity mode judgment strategy is introduced, wherein the characteristic dimension reduction specifically means a mode of only adopting the main characteristic quantities and neglecting other irrelevant variables.
From the foregoing, in one embodiment of the invention, the continuous wave cavity ring down spectroscopy apparatus further comprises a photodetector, wherein,
Detecting the optical signal transmitted out of the F-P optical resonant cavity unit by utilizing a photoelectric detector to obtain optical signal detection information after detection, wherein the optical signal detection information comprises the shape of a light spot and light intensity information;
based on the optical signal detection information, pattern recognition decision information is generated.
As can be seen from the above description, after the photodetector detects the optical signal, the light spot shape and the light intensity information can be obtained by the technical means commonly used in the technical field, according to the light spot shape and the light intensity information, the transverse mode characteristic and the longitudinal mode characteristic of the optical cavity can be extracted by the modes commonly used in the technical field, in addition, according to the light spot shape and the light intensity information, the mode identification decision information can be generated, in a possible embodiment, the mode identification decision information is generated based on the frequency of the resonant signal detected by the photodetector, and the situation of the resonant signal can refer to the above description. The adjustment of the preliminary criterion of stability is explained in detail below.
As can be seen from the above description, the corresponding optical cavity transverse mode feature and optical cavity longitudinal mode feature are extracted based on the light spot shape and the signal intensity, and the energy distribution situation on the light spot can be determined based on the optical cavity transverse mode feature, and the specific recognition method is as follows: the light intensity distribution of the cross section of the light beam is characterized by high center and radial reduction, and the central light spot is a TEM00 fundamental mode. Therefore, the judged optical cavity transverse mode characteristics are necessary conditions for generating an effective ring-down event, and the initial criterion adjustment mode for the generated stability based on the optical cavity transverse mode characteristics is as follows: when the optical cavity transverse mode is characterized as the fundamental mode and the higher order mode rejection ratio is at least 100: and 1, continuously identifying the effective ring-down events, otherwise, setting the number of the identified effective ring-down events to zero, and regenerating a stability preliminary criterion. The cases of the fundamental mode and the higher-order mode rejection ratio are consistent with the prior art, and are not described in detail here.
The High order mode rejection ratio (High-Order Mode Suppression Ratio, HOSMR) of the transverse mode characteristics of an optical cavity is a ratio describing the intensity of the fundamental mode (typically the lowest order transverse mode) relative to the High order transverse mode in the optical cavity. In lasers and optical resonators it is generally desirable that the energy of the fundamental mode is as high as possible, while the energy of the higher order modes is as low as possible, as the higher order modes may lead to reduced beam quality, energy dispersion and possible mode instability.
In general, the higher order mode rejection ratio can be obtained by direct imaging, and the beam cross-sectional image at the optical cavity exit of the F-P optical intensity resonator unit can be obtained by a photodetector. The brightness or intensity of the fundamental and higher order modes can be measured using a measurement tool in the image processing software. By analyzing the luminance distribution in the image, the intensity of the fundamental mode and the intensity of the higher order modes can be judged, wherein the higher order mode suppression ratio can be expressed as: HOSMR = fundamental mode intensity \ higher order mode intensity.
The number of effective ring-down events is determined by the longitudinal mode characteristics of the optical cavity and the linewidth characteristics of the laser light source, and specifically: the longitudinal mode characteristic of the optical cavity generates maximum gain only for light of a specific frequency (resonant frequency), and light of other frequencies can be suppressed. The primary criterion of the generated stability is adjusted by utilizing the longitudinal mode characteristics of the optical cavity and the linewidth characteristics of the laser light source, and the adjustment mode is as follows: firstly, judging the coincidence point of the line width of the laser light source and the longitudinal mode point of the optical cavity, and taking the laser control temperature at the moment as a starting value, wherein the laser control temperature at the moment is the temperature value of the regulated laser light source obtained after one-time modulation step. Judging whether the width of the longitudinal mode characteristic of the optical cavity is matched with the temperature control temperature during primary modulation, if so, continuously identifying the effective ring-down time quantity; if not, the number of identified effective ring-down events is set to zero and a stability preliminary criterion is regenerated. Specifically, the width of the longitudinal mode characteristic of the optical cavity is matched with the temperature control temperature during primary modulation, specifically, the values of the longitudinal mode characteristic and the temperature control temperature are equal, or the value difference value of the longitudinal mode characteristic and the temperature control temperature is within an allowable value range, and the allowable value can be selected according to actual needs so as to meet the actual gas detection.
The environmental characteristics and noise level characteristics may be used to correct ring down signal quality information. The specific correction mode is as follows: and extracting the deviation of the real-time ambient temperature and air pressure and the temperature reference value and the air pressure reference value, and extracting the high-frequency characteristic quantity in the optical signal, wherein the influence on the fitting degree of the ring-down signal is expressed as negative correlation. One possible modification is: firstly judging whether the real-time environment temperature is between 0 and 40 ℃ and whether the air pressure is between 80 and 110kPa, if not, regenerating a stability preliminary criterion, if so, using the absolute value of the difference value of the reference air pressure of 100kPa as an input value for fitting degree correction with the reference temperature of 25 ℃, wherein a correction factor is obtained from specific experimental data, and the reference value is-0.0018/DEGC and-0.0009/kPa.
In the specific correction, the absolute value of the temperature difference is multiplied by the temperature correction factor, the absolute value of the air pressure difference is multiplied by the air pressure correction factor, and the two products are added to obtain the correction value. And adding the correction value to the ring-down signal quality information to finish the correction of the ring-down signal quality information.
When detecting the stable state based on the stability criterion information, as can be seen from the above description and fig. 1, the method is mainly based on the number of effective ring-down events information, the fast scan frequency information and the ring-down signal quality information, wherein, when judging, the cavity mode matching efficiency is not lower than 0.5, the ring-down signal fitting degree is not lower than 0.9, that is, when the cavity mode matching efficiency is not lower than 0.5 and the ring-down signal fitting degree is not lower than 0.9, the method is considered to be in the stable state, otherwise, the method is considered to be in the unstable state.
When judging that the current is in a stable state, locking a scanning triangular wave signal of the triangular wave current; when judging the unstable state, generating wavelength modulation compensation information, wherein the generated wavelength modulation compensation information comprises a triangular wave current target frequency and a triangular wave current target amplitude which are used for regulating and controlling the triangular wave current, namely, configuring the frequency and the amplitude of the triangular wave current based on the wavelength modulation compensation information, and further realizing current modulation on the laser light source through the triangular wave current of the target frequency and the target amplitude. The target frequency is the frequency where the triangular wave current needs to be, and the target amplitude is the amplitude where the triangular wave current needs to be. In the secondary modulation, the temperature of the laser light source is maintained at the temperature state in the primary modulation.
In one embodiment of the present invention, when generating wavelength modulation compensation information based on stability criterion information, the method includes:
constructing a wavelength modulation compensation model based on a BP neural network;
Based on the stability criterion information, the wavelength modulation compensation model generates wavelength modulation compensation information.
In particular, in order to generate the wavelength modulation compensation information, a wavelength modulation compensation model needs to be built first, and the wavelength modulation compensation model can be built based on a BP neural network, wherein the BP neural network can be in a conventional common form, specifically, a wavelength modulation compensation basic model is built by using the BP neural network first, and after the wavelength modulation compensation basic model is trained to a target state, the wavelength modulation compensation model can be generated based on the wavelength modulation compensation basic model.
The BP neural network is utilized to carry out wavelength modulation compensation, and based on basic characteristics possessed by the neural network, the modulation process has complex nonlinear mapping, self-organizing, self-learning and reasoning capabilities, and only a sample is utilized to train, so that the internal relation of input and output is simulated.
For the BP neural network adopted by the wavelength modulation compensation basic model, in one embodiment of the invention, the number of hidden layers in the BP neural network is 8, the weight between an input layer and the hidden layers is upsilon, the transfer function of the hidden layers is f 1, the weight between the hidden layers and an output layer is omega jk, and the transfer function of the output layer is f 2, and at the moment, the approximate mapping of the 3-dimensional space vector to the 2-dimensional space is completed based on the wavelength modulation compensation basic model constructed by the BP network. The hidden layer transfer function f 1 and the output layer transfer function f 2 can adopt default transfer functions of the BP neural network.
The method adopts a square error function as a loss function of the BP neural network, and the mode and the process for determining the loss are consistent with the prior art when the wavelength modulation compensation basic model is trained based on the square error function.
The method and process for training the wavelength modulation compensation basic model to obtain the wavelength modulation compensation model are described below.
When training the wavelength modulation compensation basic model, a training data set is generally required to be first manufactured. One possible way to make the training dataset is:
A continuous wave cavity ring-down spectroscopy device and an adjustable triangular wave generator are provided, triangular wave current which can be loaded on a laser light source is generated by the triangular wave generator, and the frequency and the amplitude of the triangular wave current generated by the triangular wave generator are adjustable. The continuous wave cavity ring-down spectroscopy apparatus provided is consistent with the continuous wave cavity ring-down spectroscopy apparatus employed in the present invention and includes at least a laser light source, an F-P optical resonator unit, and a photodetector as described above with particular reference thereto.
And adjusting the frequency of the triangular wave current generated by scanning, the number of effective ring-down events and the fitting rate of the ring-down signal changed by adding white noise interference, randomly setting 1000 groups of training set input condition parameters with equal probability, and reading the target frequency and the target amplitude in the corresponding wavelength modulation compensation signal as an output layer. After setting the input condition parameters each time, the oscilloscope is used for collecting the output signal of the continuous wave cavity ring-down spectroscopy device, the frequency and the amplitude of the triangular wave current are adjusted until the output signal meets the stability criterion, the target frequency and the amplitude target value of the wavelength modulation compensation signal at the moment are read and recorded as the output layer, and at the moment, the training data set can be manufactured.
From the above description, for any training sample, the training sample includes an input vector and an output vector, where the input vector is a three-dimensional real value vector formed by the number of effective ring-down events, the scanning frequency and the ring-down signal fitting rate, and the output vector is wavelength modulation compensation information, that is, the triangular wave current frequency and the triangular wave current amplitude for regulating and controlling the triangular wave current.
For the training data set produced, 5-fold cross validation was used to divide the training set consisting of 1000 sets of data into 5 mutually exclusive subsets, each containing 200 sets of data. And 4 subsets of union sets are adopted as training sets each time, the rest are adopted as test sets, 5 times of training and testing are carried out, and finally, the average value of 5 times of testing results is returned.
When the wavelength modulation compensation basic model is trained, the training can be generally terminated by setting the maximum iteration number, and the maximum iteration number is generally not less than 2000 times, otherwise, the model performance is poor. In addition, the threshold value of the training error can be set at the same time, the training error can be obtained by calculating the square error between the wavelength modulation compensation basic model and the true value, the general training error threshold value is set to be 0.001-0.02 reasonably, and the training of the wavelength modulation compensation basic model is not favored by too low or too high, namely the required wavelength modulation compensation model cannot be obtained. In practice, the training error threshold is preferably set to 0.01 to obtain an acceptable training model. And determining that the termination mode of training the wavelength modulation compensation basic model is consistent with the existing mode based on the maximum iteration times and the training error threshold value, and obtaining the wavelength modulation compensation model after the training is terminated.
In order to make the neural network better converged, before the training sample data is input into the wavelength modulation compensation basic model, normalization processing is firstly performed, wherein the normalization method is as follows:
Wherein X i,m,Yi,min is the value of the input, predicted output of the mth sample; x i,max,Xi,min is the maximum value and the minimum value of the input samples of the ith group respectively, wherein the samples are any one of effective ring-down event number information, quick scanning frequency information and ring-down signal quality information; y max,Ymin is the maximum and minimum calibration values of the predicted output, wherein the predicted output is any one of the triangular wave current frequency and the triangular wave current amplitude.
When the BP neural network is trained, the normalization processing is carried out on the training sample data input, and when the wavelength modulation compensation model works, the normalization processing is also required to be carried out through the data input, and the data normalization mode can be adopted in the existing common mode, so that the requirement of the wavelength modulation compensation model on work can be met.
In summary, a turn-off-free detection and control system for continuous wave cavity ring-down spectroscopy can be obtained, and in one embodiment of the invention, the system comprises a turn-off-free detection and control processor, wherein the turn-off-free detection and control processor performs turn-off-free detection and control on a laser light source in a continuous wave cavity ring-down spectroscopy device based on the method, so as to control the laser light source to be in a turn-off-free state to detect target gas.
Specifically, the shutdown-free detection regulation processor may adopt an existing commonly used processor or computer device, the specific type may be selected according to needs, and the specific implementation manner and process of the shutdown-free control of the laser light source may refer to the above description, which is not repeated here.
Claims (10)
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202410413864.XA CN118090667B (en) | 2024-04-08 | 2024-04-08 | Shutdown-free detection and control method and system suitable for continuous wave cavity ring-down spectroscopy |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202410413864.XA CN118090667B (en) | 2024-04-08 | 2024-04-08 | Shutdown-free detection and control method and system suitable for continuous wave cavity ring-down spectroscopy |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN118090667A true CN118090667A (en) | 2024-05-28 |
| CN118090667B CN118090667B (en) | 2024-10-01 |
Family
ID=91149714
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202410413864.XA Active CN118090667B (en) | 2024-04-08 | 2024-04-08 | Shutdown-free detection and control method and system suitable for continuous wave cavity ring-down spectroscopy |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN118090667B (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN119000573A (en) * | 2024-07-11 | 2024-11-22 | 南京航空航天大学 | Method and system for matching longitudinal modes of ring-down cavity |
Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| AU2001272190B2 (en) * | 2000-07-12 | 2005-01-06 | Macquarie Research Ltd | Optical heterodyne detection in optical cavity ringdown spectroscopy |
| US20080111077A1 (en) * | 2006-11-10 | 2008-05-15 | Miller J Houston | Compact near-ir and mid-ir cavity ring down spectroscopy device |
| CN104819957A (en) * | 2015-02-11 | 2015-08-05 | 中国科学院长春光学精密机械与物理研究所 | CRDS principle-based gas concentration measurement system of continuously adjustable laser light source |
| CN113702294A (en) * | 2021-07-09 | 2021-11-26 | 北京航空航天大学 | Low-speed sampling-based ring-down cavity high-speed ring-down signal coefficient extraction method |
| CN115575350A (en) * | 2022-09-05 | 2023-01-06 | 北京市燃气集团有限责任公司 | Laser spectrum frequency matching device and method based on pressure regulation |
-
2024
- 2024-04-08 CN CN202410413864.XA patent/CN118090667B/en active Active
Patent Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| AU2001272190B2 (en) * | 2000-07-12 | 2005-01-06 | Macquarie Research Ltd | Optical heterodyne detection in optical cavity ringdown spectroscopy |
| US20080111077A1 (en) * | 2006-11-10 | 2008-05-15 | Miller J Houston | Compact near-ir and mid-ir cavity ring down spectroscopy device |
| CN104819957A (en) * | 2015-02-11 | 2015-08-05 | 中国科学院长春光学精密机械与物理研究所 | CRDS principle-based gas concentration measurement system of continuously adjustable laser light source |
| CN113702294A (en) * | 2021-07-09 | 2021-11-26 | 北京航空航天大学 | Low-speed sampling-based ring-down cavity high-speed ring-down signal coefficient extraction method |
| CN115575350A (en) * | 2022-09-05 | 2023-01-06 | 北京市燃气集团有限责任公司 | Laser spectrum frequency matching device and method based on pressure regulation |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN119000573A (en) * | 2024-07-11 | 2024-11-22 | 南京航空航天大学 | Method and system for matching longitudinal modes of ring-down cavity |
| CN119000573B (en) * | 2024-07-11 | 2025-10-17 | 南京航空航天大学 | Method and system for matching longitudinal modes of ring-down cavity |
Also Published As
| Publication number | Publication date |
|---|---|
| CN118090667B (en) | 2024-10-01 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CN111474138B (en) | Gas concentration measuring device and method based on high-frequency reference optical frequency division multiplexing technology | |
| CN118090667B (en) | Shutdown-free detection and control method and system suitable for continuous wave cavity ring-down spectroscopy | |
| CN115586162A (en) | Noise reduction method and device for laser absorption spectrum | |
| CN119064286B (en) | A gas detection method and system based on photoacoustic cell acoustic pulse excitation | |
| CN114076747B (en) | A multi-gas detection device and method based on mode-locked cavity enhanced absorption spectroscopy | |
| CN110160989A (en) | A kind of detection method and detection device of trace gas | |
| WO2002075290A1 (en) | Measuring method and device, and imaging method and device | |
| CN110135320B (en) | Spectral noise reduction method and device based on BP neural network and variance compensation | |
| Liang et al. | Suppression of interference fringes in wavelength modulation spectroscopy based on convolutional neural networks | |
| CN121049435A (en) | A method for identifying anomalies in transformer insulating oil chromatographic data | |
| CN118999823B (en) | A gas temperature measurement system and method based on laser optical technology | |
| CN116336936B (en) | Fourier domain OCT system dispersion compensation method and system based on wavelength modulation | |
| CN117743981A (en) | Transformer oil breakdown voltage prediction method based on random forest model | |
| Yan et al. | Research on a system noise simulation and filtering method in tunable diode laser absorption spectroscopy technology | |
| CN116759880A (en) | Automatic identification and laser wavelength frequency locking method based on atomic saturation absorption spectrum | |
| CN210577013U (en) | Laser generating device based on TDLAS | |
| CN120869900B (en) | Particulate matter detecting system based on laser self-mixing interference | |
| CN120385620B (en) | Infrared oil meter for driving infrared LED lamp through pulse signal | |
| CN121027042B (en) | A high-precision gas detection adaptive light intensity noise suppression system and method | |
| CN119270246B (en) | Power transmission line dynamic three-dimensional ranging method based on microwave interference | |
| CN120955439B (en) | Safety Protection Method and System for Carbon Dioxide Lasers Based on Directional Coupling | |
| CN118376602A (en) | TDLAS gas telemetry false alarm filtering method and system | |
| CN121384879A (en) | Enhanced gas concentration inversion method and system based on signal interference elimination | |
| CN119959176A (en) | A marine ammonia analysis and detection method, system, storage medium and program product | |
| CN118937234A (en) | Gas detection method, system and computer readable storage medium |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination | ||
| GR01 | Patent grant | ||
| GR01 | Patent grant |