CN115275772B

CN115275772B - TDLAS technology-based specific time laser wavelength control method and device

Info

Publication number: CN115275772B
Application number: CN202211171375.5A
Authority: CN
Inventors: 陈更甫; 陈杰甫; 伏思越
Original assignee: Nanjing Xuao Technology Co ltd
Current assignee: Nanjing Xuao Technology Co ltd
Priority date: 2022-09-26
Filing date: 2022-09-26
Publication date: 2022-12-16
Anticipated expiration: 2042-09-26
Also published as: CN115275772A

Abstract

The invention relates to a method and a device for controlling laser wavelength at a specific moment based on a TDLAS technology, wherein the method comprises the following steps: the method comprises the steps that a semiconductor laser is tested in advance by using an existing spectrometer, the output characteristic of the semiconductor laser is obtained, and parameter information corresponding to the semiconductor laser is obtained on the basis of a preset wavelength; controlling the working temperature and the working current of the semiconductor laser by using a temperature controller and a current controller; detecting a signal of laser output by the semiconductor laser after passing through the standard air chamber by using a photoelectric detector; the method comprises the steps that whether the working temperature or the working current of the semiconductor laser needs to be adjusted or not is detected by the signal processor, if yes, the working current setting and the working temperature setting of the semiconductor laser are adjusted by the temperature controller and the current controller until the working temperature and the working current meet the standard, and if not, the current working temperature and the current working current are stored in the signal processor or the cloud server, so that the semiconductor laser outputs laser with preset wavelength at a specific moment, and dynamic frequency stabilization is achieved.

Description

TDLAS technology-based specific time laser wavelength control method and device

Technical Field

The invention relates to the technical field of optoelectronic devices, in particular to a method and a device for controlling laser wavelength at a specific moment based on a TDLAS technology.

Background

The tunable semiconductor laser absorption spectrum technology is characterized in that the continuous tuning output of the output wavelength of a DFB laser is realized by changing the driving current, when a tuning range can sweep a certain absorption area of gas to be detected, the absorption degree of the gas to be detected can be obtained by obtaining the variation curve of laser intensity in a scanning interval, when a scanning function (triangular wave and sawtooth wave) is superposed with a high-frequency modulation signal, demodulation is carried out at a receiving end through phase-locked amplification, and the amplitude of a second harmonic is known to be in direct proportion to the effective optical path of the gas to be detected according to mathematical relations, so that the lower limit of the detection concentration can be greatly reduced by sweeping the gas absorption area by using the DFB laser of a tunable single frequency, meanwhile, the 1f noise is reduced by using the high-frequency modulation, the detection precision is improved, and the concentration detection system based on the TDLAS technology has low cost and is based on a plurality of advantages, so that the TDLAS is very suitable for commercialization.

In practical applications, the output wavelength of the DFB semiconductor laser is required to operate according to system requirements, but the DFB laser is affected by external environment changes (temperature, humidity, vibration, etc.) even under specific driving parameters to cause frequency drift, and in special applications, the target wavelength (frequency) is required to be output at a specific moment in a scanning half period.

The currently practical frequency stabilization techniques for semiconductor lasers mainly include PDH techniques, saturated absorption frequency stabilization techniques, two-color frequency lock techniques, MTS (modulation transfer) frequency stabilization techniques, etc., but the structures are complex and have severe requirements for the environment, and the above techniques are mainly used for static frequency stabilization techniques under specific parameters, i.e., the output wavelength of a laser light source is stabilized at a certain target wavelength, and the target wavelength cannot be output at a specific time in a dynamic system.

In patent CN114142332A, the all-fiber device and the modulation transfer spectrum technology are used to reduce the harsh requirements of the device on the environment, reduce the influence caused by environmental disturbance, and improve the stability of frequency stabilization, however, this method cannot realize dynamic frequency stabilization, that is, cannot output the target center wavelength at a specific time.

In summary, the existing laser wavelength control method has the problems of complex structure, high cost and incapability of realizing dynamic frequency stabilization.

Disclosure of Invention

Therefore, the technical problem to be solved by the invention is to overcome the problems that the laser wavelength control method in the prior art is complex in structure, high in cost and incapable of realizing dynamic frequency stabilization.

In order to solve the above technical problem, the present invention provides a method for controlling a laser wavelength at a specific time based on a TDLAS technology, comprising:

the method comprises the steps that a semiconductor laser is tested in advance by using an existing standard spectrum instrument, the output characteristic of the semiconductor laser is obtained, and parameter information corresponding to the semiconductor laser is obtained based on a preset wavelength, wherein the parameter information comprises but is not limited to a calibration curve, a reference working temperature and a reference working current;

in the TDLAS system, a temperature controller is used for controlling the working temperature of the semiconductor laser according to the reference working temperature, and a current controller is used for controlling the working current of the semiconductor laser according to the reference working current;

after the TDLAS system works normally, a photoelectric detector is used for detecting an optical signal of laser output by the semiconductor laser after passing through the standard air chamber so as to obtain a working curve of the semiconductor laser;

acquiring errors of the working curve and the calibration curve by using a signal processor, and comparing the errors with a first error threshold value;

if the error is larger than a first error threshold value, adjusting the working temperature of the semiconductor laser by using a temperature controller until the error is not larger than the first error threshold value;

and if the error is less than or equal to a first error threshold value, adjusting the working current of the semiconductor laser by using a current controller, and adjusting the scanning step length according to the working current, so that the semiconductor laser outputs laser with a preset wavelength at a specific moment in the TDLAS system.

Preferably, the obtaining the error of the working curve and the calibration curve by using the signal processor comprises:

under the condition that the preset wavelength output is realized at a specific moment in a frequency sweeping period in the TDLAS technology, acquiring a calibration curve of a second harmonic signal subjected to amplitude normalization of a first harmonic signal at the moment as a reference signal;

in the dynamic adjustment, acquiring a working curve of a second harmonic signal normalized by a first harmonic signal as an actual signal;

and calculating the difference between the peak-to-peak value and the central position characteristic parameter between the reference signal and the actual signal to obtain the error of the working curve and the calibration curve.

Preferably, the acquiring parameter information corresponding to the semiconductor laser based on the preset wavelength includes:

the method comprises the steps that a semiconductor laser is tested in advance by using an existing standard spectrum instrument, and a first corresponding relation between the working temperature of the semiconductor laser and the output wavelength and a second corresponding relation between the working current of the semiconductor laser and the output wavelength are obtained;

and acquiring parameters such as reference working temperature and reference working current corresponding to the center wavelength of the semiconductor laser at the specific moment in a preset wavelength in the TDLAS system based on the first corresponding relation and the second corresponding relation.

Preferably, if the error is less than or equal to the first error threshold, adjusting the operating current of the semiconductor laser by using a current controller, and adjusting the scanning step length according to the operating current, so that the semiconductor laser outputting the laser with the preset wavelength at the specific time in the TDLAS system includes:

if the error is less than or equal to a first error threshold value, comparing the error with a second error threshold value;

if the error is less than or equal to a second error threshold, current scanning is carried out by taking the current working current of the semiconductor laser as a center, and the working current of the semiconductor laser is adjusted;

acquiring a second error of the working curve and the calibration curve of the adjusted semiconductor laser by using a signal processor, and comparing the second error with a third error threshold value;

if the second error is less than or equal to a third error threshold, adjusting the scanning step length according to the current working current and the scanning duration of the semiconductor laser, so that the semiconductor laser outputs laser with a preset wavelength at a specific moment in the TDLAS system;

wherein the first error threshold is greater than the second error threshold, which is greater than the third error threshold.

Preferably, if the error is less than or equal to the first error threshold, adjusting the operating current of the semiconductor laser by using a current controller, and adjusting the scanning step length according to the operating current, so that the semiconductor laser outputs laser with a preset wavelength at a specific time in the TDLAS system further includes:

if the error is larger than the second error threshold and smaller than or equal to the first error threshold, scanning the range [ I ] based on an approximation algorithm ₁ ,I ₂ ]And a scanning duration of 2T, with a scanning step length I _scan1 ＝(I ₂ -I ₁ ) Performing current scanning at the speed of 2T, adjusting the working current of the semiconductor laser, acquiring a third error of a current working curve and a calibration curve by using a signal processor, and comparing the third error with each error threshold value;

if the third error is less than or equal to a third error threshold, acquiring a working current I corresponding to the center wavelength of the current output laser of the semiconductor laser _m1 In 1 with _m1 For the scan center, determine the scan range [ I ₁₂ ,I ₂₂ ]Current scanning is carried out on the semiconductor laser, and the working current of the semiconductor laser is adjusted;

wherein, I ₁₂ ≥I ₁ ,I ₂₂ ≤I ₂ 。

Preferably, the compound I _m1 For the scan center, determine the scan range [ I ] ₁₂ ,I ₂₂ ]Current scanning is performed on the semiconductor laser, and adjusting the working current of the semiconductor laser comprises:

obtaining a scan Range [ I ₁₂ ,I ₂₂ ]Corresponding average scanning step length I _scan2 And judging the average scanning step length I _scan2 Current resolution I corresponding to semiconductor laser _DAC In which I _scan2 ＝|I ₁₂ -I ₂₂ |/2T；

If the average scanning step length I _scan2 Less than the current resolution I corresponding to the semiconductor laser _DAC At the current resolution I _DAC As a scanning step with said operating current I _m1 Adopting a self-increasing and self-decreasing algorithm to carry out current scanning for a scanning center, and adjusting the working current of the semiconductor laser;

if the average scanning step length I _scan2 The current resolution ratio I corresponding to the semiconductor laser is larger than or equal to _DAC In the scanning range [ I ] ₁₂ ,I _m1 ]And a scanning range [ I _m1 ,I ₂₂ ]And respectively performing current scanning as target scanning ranges to adjust the working current of the semiconductor laser.

Preferably, the scanning range [ I ] ₁₂ ,I _m1 ]And a scanning range [ I _m1 ,I ₂₂ ]Respectively as the target scanning scope to carry out current scanning, and the adjustment of the working current of the semiconductor laser comprises the following steps:

in coarse scanning step length I _c Duration of scan [0, T/2]Respectively scan at the targetCarrying out coarse scanning within the range, and adjusting the working current of the semiconductor laser;

acquiring a fourth error of the current working curve and the calibration curve of the semiconductor laser by using a signal processor, and judging the magnitude of the fourth error and the magnitude of a third error threshold;

if the fourth error is larger than the third error threshold, using the fine scanning step length I _s Duration of scan [ T/2, T]Respectively performing fine scanning in a target scanning range, and adjusting the working current of the semiconductor laser;

wherein, I _c +I _s ＝2I _scan2 ，I _DAC ≤I _s <I _scan2 <I _c <2I _scan2 。

Preferably, if the fourth error is larger than the third error threshold, the step length I is scanned finely _s Duration of scan [ T/2, T]Respectively carrying out fine scanning in a target scanning range, and adjusting the working current of the semiconductor laser comprises the following steps:

acquiring a fifth error of a current working curve and a calibration curve of the semiconductor laser by using a signal processor, and judging the size of the fifth error and a third error threshold;

if the fifth error is less than or equal to a third error threshold value, acquiring a working current I corresponding to the center wavelength of the current output laser of the semiconductor laser _m2 Calculating Δ I, Δ I = | I _m2 -I _m1 |；

Comparison of Δ I and I _DAC If Δ I is less than or equal to I _DAC Adjusting the scanning step length according to the current working current and the scanning duration of the semiconductor laser, so that the semiconductor laser outputs laser with preset wavelength at a specific moment in the TDLAS system;

if Δ I>I _DAC Then the value of the fine scanning step length is I _s Each time one I is reduced _DAC Performing a fine scanning operation once, and adjusting the working current of the semiconductor laser until the semiconductor laser meets a preset condition;

wherein the preset condition is I _s ＝I _DAC Or | I _m3 -I _m2 |≤I _DAC ，I _m3 And when the error between the working curve and the calibration curve of the semiconductor laser acquired by the signal processor after fine scanning adjustment is less than or equal to a third error threshold value, the working current corresponding to the central wavelength of the output laser of the semiconductor laser.

The invention also provides a TDLAS technology-based specific time laser wavelength control device, which realizes the TDLAS technology-based specific time laser wavelength control method and comprises the following steps:

the standard spectrum instrument is used for testing the semiconductor laser in advance, acquiring the output characteristic of the semiconductor laser and acquiring the parameter information corresponding to the semiconductor laser based on the preset wavelength;

a TDLAS system, comprising:

a semiconductor laser;

the temperature controller is used for adjusting the working temperature of the semiconductor laser;

the current controller is used for adjusting the working current of the semiconductor laser;

the lower computer of the temperature controller is used for acquiring the working temperature of the semiconductor laser and feeding the working temperature back to the temperature controller so as to finely adjust and accurately set the working temperature of the semiconductor laser;

the standard air chamber is used for outputting laser output by the semiconductor laser to a standard device of an optical signal after passing through the standard air chamber;

the photoelectric detector is used for detecting the laser signal output after passing through the standard gas chamber;

the signal processor is used for acquiring a working curve of the laser signal detected by the photoelectric detector and calculating the error between the working curve and the calibration curve;

and the industrial personal computer is used for acquiring the error of the working curve and the calibration curve calculated by the signal processor and the working current of the semiconductor laser, comparing the error with an error threshold value, calculating to obtain a current feedback signal through the working current and the comparison result of the error and the error threshold value, outputting the current feedback signal to the current controller so as to adjust the working current of the semiconductor laser, and adjusting the scanning step length according to the working current, so that the semiconductor laser outputs laser with preset wavelength at a specific moment in the TDLAS system.

Preferably, the industrial personal computer comprises:

the comparison calling module is used for comparing the error of the working curve and the calibration curve of the semiconductor laser with the error threshold value and calling a scanning unit or a parameter storage module in the PID and approximation algorithm processing module according to the error and the error threshold value;

the PID and approximation algorithm processing module is used for obtaining a working current value meeting the error requirement by adopting a PID algorithm and an approximation algorithm according to the scanning unit called by the comparison calling module;

the parameter storage module is used for storing the working temperature and the working current meeting the error requirement into the signal processor or the cloud server;

and the step length adjusting module is used for adjusting the scanning step length according to the working current and the current scanning duration stored by the parameter storage module, so that the semiconductor laser outputs laser with preset wavelength at a specific moment in the TDLAS system.

The TDLAS technology-based specific time laser wavelength control method utilizes the existing standard spectrum instrument to pre-test a semiconductor laser to obtain the output characteristic of the semiconductor laser, obtains a calibration curve, a reference working temperature and a reference working current corresponding to the semiconductor laser based on the preset wavelength, transmits the reference working temperature and the reference working current into a temperature control circuit and a current control circuit, controls the working temperature of the semiconductor laser by utilizing a temperature controller, and controls the working current of the semiconductor laser by utilizing a current controller, and because the temperature regulation and the current regulation have great influence on the laser wavelength, the TDLAS technology-based specific time laser wavelength control method can regulate the working current of the semiconductor laser to realize the compensation of large wavelength fluctuation and can regulate the working temperature of the semiconductor laser to realize the compensation of small wavelength fluctuation; the method comprises the steps that the central wavelength and the working curve are obtained by detecting the output laser of the semiconductor laser, whether the central wavelength and the preset wavelength deviate under the current and temperature conditions can be known by comparing the working curve with the calibration curve, so that the working temperature or the working current is adjusted, if the deviation does not occur, the current working temperature and the working current are stored in a signal processor for subsequent debugging, whether the central wavelength deviates from the preset wavelength or not is judged by comparing the working curve with the calibration curve, the deviation comprises the time deviation and the wavelength deviation, the deviation is not calculated through the temperature change of a tube core, the error is reduced, and the deviation degree of the central wavelength and the preset wavelength is more accurately reflected; and the scanning step length is adjusted according to the working current and the scanning time length of the semiconductor laser, so that the semiconductor laser outputs laser with preset wavelength at a specific moment in a TDLAS system, dynamic frequency stabilization is realized, the requirement that the target central wavelength is output at the specific moment in actual detection engineering is met, the system is simple in structure and low in cost.

Drawings

In order that the present disclosure may be more readily understood, a more particular description of the disclosure will be rendered by reference to specific embodiments thereof which are illustrated in the appended drawings

Fig. 1 is a flowchart of a laser wavelength control method at a specific time based on the TDLAS technique;

FIG. 2 is a schematic diagram of errors in obtaining a calibration curve and a working curve;

fig. 3 is a schematic diagram illustrating a laser wavelength control method at a specific time based on the TDLAS technique;

fig. 4 is a schematic diagram illustrating a principle of adjusting an operating current of a semiconductor laser according to an embodiment of the present disclosure;

fig. 5 is a schematic diagram illustrating another principle of adjusting the operating current of a semiconductor laser according to an embodiment of the present disclosure;

fig. 6 is a block diagram illustrating a laser wavelength control apparatus for a specific time based on the TDLAS technique;

fig. 7 is a block diagram of an industrial control machine in a laser wavelength control device at a specific time based on the TDLAS technology;

fig. 8 is a block diagram of an industrial control machine in another time-specific laser wavelength control device based on the TDLAS technology according to an embodiment of the present disclosure.

Detailed Description

The present invention is further described below in conjunction with the following figures and specific examples so that those skilled in the art may better understand the present invention and practice it, but the examples are not intended to limit the present invention.

Example 1:

referring to fig. 1, a method for controlling a laser wavelength at a specific time based on a TDLAS technique according to an embodiment of the present invention includes:

s1: the method comprises the steps that an existing standard spectrum instrument is used for testing a semiconductor laser in advance to obtain the output characteristic of the semiconductor laser, and parameter information corresponding to the semiconductor laser is obtained based on a preset wavelength, wherein the parameter information comprises but is not limited to a calibration curve, a reference working temperature and a reference working current;

the obtaining of the parameter information corresponding to the semiconductor laser based on the preset wavelength specifically includes:

s10: the method comprises the steps that a semiconductor laser is tested in advance by using an existing standard spectrum instrument, and a first corresponding relation between the working temperature of the semiconductor laser and the output wavelength and a second corresponding relation between the working current of the semiconductor laser and the output wavelength are obtained;

s11: and acquiring parameters such as reference working temperature and reference working current corresponding to the center wavelength of the semiconductor laser at the specific moment in a preset wavelength in the TDLAS system based on the first corresponding relation and the second corresponding relation.

The central wavelength of the semiconductor laser is the wavelength corresponding to the central position of the full width at half maximum of the spectrum measured at a certain temperature, and the full width at half maximum is the wavelength difference corresponding to the time when the intensity on two sides of the spectrum peak value is reduced to one half of the peak value; in this embodiment, the preset wavelength is not limited, and may be 500nm, 1300nm, 1600nm, or the like;

in some optional embodiments, the output characteristic of the semiconductor laser is used to indicate a first corresponding relationship between the operating current and the center wavelength of the output laser light, and the operating current corresponding to the center wavelength of the output laser light of the semiconductor laser is obtained based on the first corresponding relationship and the center wavelength of the output laser light.

S2: in the TDLAS system, a temperature controller is used for controlling the working temperature of the semiconductor laser according to the reference working temperature, and a current controller is used for controlling the working current of the semiconductor laser according to the reference working current;

s3: after the TDLAS system works normally, a photoelectric detector is used for detecting an optical signal of laser output by the semiconductor laser after passing through the standard air chamber so as to obtain a working curve of the semiconductor laser;

in some optional embodiments, the obtaining of the operating curve of the semiconductor laser comprises:

detecting the output laser of the semiconductor laser by using a photoelectric detector to obtain a corresponding electric signal and outputting the electric signal to a signal processor;

and demodulating the electric signal by using a signal processor to obtain a working curve corresponding to the semiconductor laser.

S4: acquiring errors of a working curve and a calibration curve of the semiconductor laser by using a signal processor, and comparing the errors with a first error threshold value;

in this embodiment, the error calculation step between the working curve and the calibration curve is as follows:

in the implementation of dynamic adjustment, a working curve of a second harmonic signal normalized by a first harmonic signal is obtained and used as an actual signal;

As shown in fig. 2, Δ y is the difference between the reference signal and the actual signal at the peak-to-peak value, and Δ x is the difference between the reference signal and the actual signal at the center position characteristic parameter.

S5: if the error is larger than a first error threshold value, adjusting the working temperature of the semiconductor laser by using a temperature controller until the error is not larger than the first error threshold value; and if the error is less than or equal to a first error threshold value, adjusting the working current of the semiconductor laser by using a current controller, and adjusting the scanning step length according to the working current, so that the semiconductor laser outputs laser with a preset wavelength at a specific moment in the TDLAS system.

When the error is larger than a first error threshold value, the central wavelength of the semiconductor laser under the conditions of the current working current and the working temperature is greatly deviated from the preset wavelength, and the working temperature and the working current of the semiconductor laser need to be recalibrated; in practical application, if the signal processor detects that the central wavelength of the output laser is very close to the preset wavelength at the current working temperature and working current of the semiconductor laser, the working temperature or working current of the semiconductor laser does not need to be adjusted, the working current and working temperature of the semiconductor laser are stored in the signal processor or a cloud server, and the scanning step length is adjusted according to the current working current and current scanning duration of the semiconductor laser, so that the semiconductor laser outputs the laser with the preset wavelength at a specific moment in the TDLAS system.

As shown in fig. 3, if the error in step S5 is less than or equal to the first error threshold, the method further includes:

s50: comparing the error with a second error threshold, and if the error is less than or equal to the second error threshold, performing current scanning by taking the current working current of the semiconductor laser as a center, and adjusting the working current of the semiconductor laser;

when the error is smaller than or equal to the second error threshold, it is indicated that the central wavelength and the preset wavelength under the conditions of the current working temperature and the working current have small amplitude deviation, and the current working current of the semiconductor laser is relatively close to the working current corresponding to the central wavelength and the preset wavelength, at this time, the working current can be finely adjusted, current scanning is performed by taking the current working current as a scanning center, the working current of the semiconductor laser is adjusted, and the required working current can be quickly positioned.

S51: acquiring a second error of a working curve and a calibration curve of the semiconductor laser after the working current is adjusted by using the signal processor, and comparing the second error with a third error threshold value;

s52: if the second error is less than or equal to a third error threshold, adjusting the scanning step length according to the current working current and the scanning duration of the semiconductor laser, so that the semiconductor laser outputs laser with a preset wavelength at a specific moment in the TDLAS system;

for example, the current operating current of the semiconductor laser is 70mA, the current scanning duration is 100ms, the scanning range may be [30ma,110ma ], and the scanning step size may be adjusted to 1mA/ms, so that the center wavelength of the output laser in the scanning period of the semiconductor laser, that is, the 40 th ms of the whole scanning process, is the preset wavelength.

Wherein the first error threshold is greater than a second error threshold, which is greater than a third error threshold.

By calculating the error between the working curve and the calibration curve, the offset of the central wavelength and the preset wavelength of the semiconductor laser under the conditions of the current working temperature and the working current is reflected, and different wavelength compensation strategies are adopted under the condition of different offsets, so that the central wavelength of the output laser of the semiconductor laser can quickly reach the preset wavelength, and the compensation efficiency is higher.

As shown in fig. 4, if the error in step S5 is less than or equal to the first error threshold, the method further includes:

s60: comparing the error with a second error threshold, if the error is greater than the second error threshold and less than or equal to the first error threshold, scanning the range [ I ] based on an approximation algorithm ₁ ,I ₂ ]And a scanning duration of 2T, with a scanning step length I _scan1 ＝(I ₂ -I ₁ ) Performing current scanning at 2T, and adjusting the working current of the semiconductor laser;

when the error is between the first error threshold and the second error threshold, it indicates that the central wavelength under the current working temperature and working current conditions has a large amplitude deviation from the preset wavelength, and only the working current is adjusted without adjusting the working temperature of the semiconductor laser, and an approximation algorithm is adopted to perform a preset large scanning range [ I [ ] ₁ ,I ₂ ]Current scanning is performed to adjust the operating current of the semiconductor laser, and in other embodiments of the present invention, the scanning range [ I ₁ ,I ₂ ]Or determined based on the corresponding operating current of the semiconductor laser at the preset wavelength.

S61: acquiring a third error of a current working curve of the semiconductor laser and the calibration curve by using a signal processor, and comparing the third error with a third error threshold value;

s62: if the third error is less than or equal to a third error threshold, acquiring a working current I corresponding to the center wavelength of the current output laser of the semiconductor laser _m1 In the first place _m1 For the scan center, determine the scan range [ I ] ₁₂ ,I ₂₂ ]Current scanning is carried out on the semiconductor laser, and the working current of the semiconductor laser is adjusted; wherein, I ₁₂ ≥I ₁ ,I ₂₂ ≤I ₂ 。

Thus, when the error is greater than the second error threshold and less than the first error threshold, first in the scanning range [ I ] ₁ ,I ₂ ]Carrying out average scanning once internally, acquiring a third error of a working curve and a calibration curve of the semiconductor laser in real time in the scanning process, and when the third error is less than or equal to a third error threshold, indicating that the working current I corresponding to the central wavelength of the output laser of the semiconductor laser at the moment _m1 Very close to the working current corresponding to the preset wavelength of the central wavelength, wherein I is used _m1 For the scan center, a new scan range [ I ] is determined ₁₂ ,I ₂₂ ]And scanning is performed again, so that the operating current of the semiconductor laser is finely adjusted.

When the error is larger, firstly, average scanning is carried out in a larger range, the approximate range of the required current is quickly locked through detecting the error in real time, and then, scanning is carried out in the range, so that the current regulation and control efficiency is greatly improved.

In this embodiment, specific values of the first error threshold, the second error threshold, and the third error threshold are not limited, and in some specific embodiments, for example: the preset error threshold is 8%, the second error threshold is 5%, and the third error threshold is 3%.

Example 2:

based on the foregoing embodiment 1, this embodiment is a further optimization of step S62 in the foregoing embodiment, as shown in fig. 5, and specifically includes:

s620: obtaining a scan Range [ I ₁₂ ,I ₂₂ ]Corresponding average scanning step length I _scan2 And judging the average scanning step length I _scan2 Current resolution I corresponding to semiconductor laser _DAC In which I _scan2 ＝|I ₁₂ -I ₂₂ |/2T；

S621: if the average scanning step length I _scan2 Less than the current resolution I of the semiconductor laser _DAC At the current resolution I _DAC As a scanning step with said operating current I _m1 Adopting a self-increasing and self-decreasing algorithm to carry out current scanning for a scanning center, and adjusting the working current of the semiconductor laser;

s622: if the average scanning step length I _scan2 Current resolution I greater than or equal to that of semiconductor laser _DAC In the scanning range [ I ] ₁₂ ,I _m1 ]And a scanning range [ I _m1 ,I ₂₂ ]Respectively as the target scanning scope and carry out current scanning, adjust the operating current of semiconductor laser, it specifically includes:

step a: in coarse scanning step I _c Duration of scan [0, T/2]Respectively carrying out coarse scanning in the target scanning range, and adjusting the working current of the semiconductor laser;

step b: acquiring a fourth error of the current working curve of the semiconductor laser and the calibration curve by using a signal processor, and judging the magnitude of the fourth error and the magnitude of a third error threshold;

step c: if the fourth error is larger than the third error threshold, respectively scanning with a fine scanning step length I in the target scanning range _s Duration of scan [ T/2, T]Respectively performing fine scanning in a target scanning range, and adjusting the working current of the semiconductor laser; wherein, I _c +I _s ＝2I _scan2 ，I _DAC ≤I _s <I _scan2 <I _c <2I _scan2 。

From this, a new scan range [ I ] is determined ₁₂ ,I ₂₂ ]Then, firstly, the average scanning step length I is calculated according to the scanning range _scan2 When I is _scan2 Very small, less than I _DAC When is in use, with I _DAC As a scanning step, with I _m1 For the scan centre, the current scan is performed using a self-increasing self-decreasing algorithm, e.g. the operating current may be I in turn _m1 +I _DAC ,I _m1 -I _DAC ,I _m1 +2I _DAC ,I _m1 -2I _DAC To quickly approximate the required current.

When I is _scan2 Is far greater than I _DAC When is in use, with I _m1 As a center, scan the range [ I ] ₁₂ ,I ₂₂ ]Divided into two parts, each being [ I ] ₁₂ ,I _m1 ]And [ I _m1 ,I ₂₂ ]And aiming at any part, firstly carrying out coarse scanning, and simultaneously carrying out the coarse scanning on the two parts, and if the required working current is not swept by the coarse scanning, carrying out fine scanning, wherein the step length of the coarse scanning is greater than that of the fine scanning, and the value of the step length can be adjusted according to actual needs.

Scanning is carried out by adopting a scanning mode combining coarse scanning and fine scanning in a scanning range, the advantages of both coarse scanning and fine scanning are taken into consideration, if the required working current is swept by the coarse scanning, the fine scanning is not required, if the required working current is not swept by the coarse scanning, the fine scanning is carried out, the operation amount of the coarse scanning is small, the operation resources can be saved, the scanning points of the fine scanning are denser, and the accuracy is higher.

Example 3:

based on the foregoing embodiment 2, after the step S622, the method further includes:

s70: in fine scanning steps I _s Duration of scan [ T/2, T]Respectively carrying out fine scanning in a target scanning range, adjusting the working current of the semiconductor laser, then obtaining a fifth error of a current working curve and a calibration curve of the semiconductor laser by using a signal processor, and judging the size of the fifth error and a third error threshold;

s71: if the fifth error is less than or equal to a third error threshold value, acquiring a working current I corresponding to the center wavelength of the current output laser of the semiconductor laser _m2 Calculating Δ I, Δ I = | I _m2 -I _m1 |；

S72: comparison of Δ I and I _DAC If Δ I is less than or equal to I _DAC Adjusting the scanning step length according to the current working current and the scanning duration of the semiconductor laser, so that the semiconductor laser outputs laser with preset wavelength at a specific moment in the TDLAS system;

s73: if Δ I>I _DAC Then the value of the fine scanning step length is set to I _s Each time one I is reduced _DAC Performing a fine scanning operation once, and adjusting the working current of the semiconductor laser until the semiconductor laser meets a preset condition;

wherein the preset condition is I _s ＝I _DAC Or | I _m3 -I _m2 |≤I _DAC ，I _m3 When the error between the working curve and the calibration curve of the semiconductor laser obtained by the signal processor after each fine scanning adjustment is less than or equal to a third error threshold value, the working current corresponding to the central wavelength of the output laser of the semiconductor laser is obtained;

when the fifth error degree is less than or equal to the third error threshold, the working current I corresponding to the central wavelength of the output laser of the semiconductor laser at the moment is indicated _m2 Working current corresponding to the preset wavelength close to the central wavelength is calculated _m2 And I _m1 When the difference is small, I can be regarded as _m2 Approximate required current, will _m2 As the corresponding working current when the central wavelength is the preset wavelength; when the difference was small, it was indicated that I _m2 And I _m1 And adjusting the scanning step length, and continuing to perform fine scanning operation until the value closer to the required working current is obtained.

Thus, during a repeated fine scan, the scan step size is gradually decreased until it equals the minimum current resolution of the semiconductor laser, indicating that the scan step size is sufficiently small, or, at the present resolution, the scan step size is reduced，I _m2 And I _m1 The value of the working current which is closer to the required working current cannot be regulated and controlled, and the working current I corresponding to the central wavelength of the current output laser can be adjusted and controlled according to the two conditions _m3 As the corresponding working current when the closest central wavelength is the preset wavelength.

The embodiment of the present invention further provides a laser wavelength control device at a specific time based on the TDLAS technology, as shown in fig. 6, including:

a TDLAS system, comprising:

a semiconductor laser 210;

a temperature controller 220 for adjusting the operating temperature of the semiconductor laser;

a current controller 230 for adjusting the operating current of the semiconductor laser;

the temperature controller lower computer 240 is used for acquiring the working temperature of the semiconductor laser and feeding the working temperature back to the temperature controller so as to finely adjust and accurately set the working temperature of the semiconductor laser;

the standard air chamber 250 is a standard device for outputting light signals after the laser output by the semiconductor laser passes through the standard air chamber;

a photoelectric detector 260 for detecting the laser signal output after passing through the standard gas chamber;

a signal processor 270, configured to obtain a working curve of the laser signal detected by the photodetector, and calculate an error between the working curve and the calibration curve;

the industrial computer 280 is used for obtaining the working curve calculated by the signal processor, the error of the calibration curve and the working current of the semiconductor laser, comparing the error with an error threshold value, calculating the current feedback signal output to the current controller by the working current and the comparison result of the error and the error threshold value so as to adjust the working current of the semiconductor laser, and adjusting the scanning step length according to the working current, so that the semiconductor laser outputs the laser with the preset wavelength at the specific moment in the TDLAS system.

The temperature controller accurately sets the working temperature of the semiconductor laser in a manual coarse adjustment mode and a lower computer fine adjustment mode, the current controller generates high-stability current to the semiconductor laser, the photoelectric detector is used for detecting an absorption spectrum passing through a sample, the PID and approximation algorithm processing center rapidly finds the working current meeting requirements by adopting PID and approximation algorithm, the temperature micro-control processing center finely adjusts the working temperature of the semiconductor laser, and the signal processor processes and analyzes the acquired signals to generate adjusting signals. Acquiring an error signal of low-frequency scanning through current low-frequency scanning, and feeding the error signal back to a current setting end to realize stable setting of current;

the TDLAS system described in the figures is a general implementation system that includes all necessary devices (subsystems) for implementing the TDLAS technique, and only shows the actual devices (subsystems) of the present embodiment.

Based on above-mentioned specific moment laser wavelength controlling means based on TDLAS technique, as shown in FIG. 7, the industrial computer includes:

a comparison and calling module 31, configured to compare errors of a working curve and a calibration curve of the semiconductor laser with an error threshold, and call a scanning unit or a parameter storage module in the PID and approximation algorithm processing module according to the errors and the error threshold, where the comparison and calling module includes a comparison sub-module and a calling sub-module;

the PID and approximation algorithm processing module 32 is used for obtaining a working current value meeting the error requirement by adopting a PID algorithm and an approximation algorithm according to the scanning unit called by the comparison calling module, wherein the PID and approximation algorithm processing module comprises a scanning submodule;

the parameter storage module 33 is used for storing the working temperature and the working current meeting the error requirement into the signal processor or the cloud server;

and a step length adjusting module 34, configured to adjust a scanning step length according to the working current and the current scanning duration stored in the parameter storage module, so that the semiconductor laser outputs laser with a preset wavelength at a specific time in the TDLAS system.

The device comprises a comparison calling module in the industrial personal computer, a scanning submodule or a parameter storage module in a PID and approximation algorithm processing module, wherein the comparison calling module is used for obtaining the error of a working curve and a calibration curve of the semiconductor laser, the error is compared with an error threshold value, the scanning submodule or the parameter storage module in the PID and approximation algorithm processing module is called according to the comparison result, the scanning submodule calculates the scanning range and the scanning step length by using an approximation algorithm and feeds the scanning range and the scanning step length back to a current controller, the current controller can conveniently scan current according to a feedback signal and adjust the working current of the semiconductor laser, the parameter storage module stores the working current meeting the error requirement into a signal processor or a cloud server, the step length adjusting module adjusts the scanning step length according to the stored working current and the current scanning duration and inputs the working current and the scanning step length into the current controller, and the current controller can conveniently control the semiconductor laser to output laser with preset wavelength at a specific moment.

Based on above-mentioned specific moment laser wavelength controlling means based on TDLAS technique, as shown in FIG. 8, the industrial computer specifically includes:

a first error comparing unit 310, configured to compare the first error with the magnitude of each error threshold;

a first calling unit 311, configured to call a first scanning unit when the first error is less than or equal to a second error threshold, and call a second scanning unit when the first error is greater than the second error threshold and less than or equal to the first error threshold;

the first scanning unit 320 is configured to perform current scanning to adjust the working current of the semiconductor laser by using the current working current of the semiconductor laser as a scanning center; the second scanning unit 321 is used for scanning the range [ I ₁ ,I ₂ ]And a scanning duration of 2T, with a scanning step length I _scan1 ＝(I ₂ -I ₁ ) Performing current scanning at 2T to adjust the working current of the semiconductor laser;

a second error comparing unit 312, configured to compare the second error of the working curve and the calibration curve of the semiconductor laser adjusted by the first scanning unit with a third error threshold; comparing the third error of the working curve and the calibration curve of the semiconductor laser adjusted by the second scanning unit with the third error threshold value;

a second calling unit 313, configured to call the parameter storage module when the second error is smaller than or equal to a third error threshold, and call a third scanning unit when the third error is smaller than or equal to the third error threshold;

the third scanning unit 322 operates at the present operating current I of the semiconductor laser _m1 For the scan center, determine the scan range [ I ₁₂ ,I ₂₂ ]Current scanning is carried out on the semiconductor laser, and the working current of the semiconductor laser is adjusted; wherein, I ₁₂ ≥I ₁ ,I ₂₂ ≤I ₂ 。

Step size comparison unit 314 for comparing I _scan2 Current resolution I corresponding to semiconductor laser _DAC Size of (1), I _scan2 ＝|I ₁₂ -I ₂₂ |/2T；

A third calling unit 315 for calling when I _scan2 Is less than I _DAC A fourth scanning unit is called; when I _scan2 Not less than I _DAC Then, calling a fifth scanning unit;

the fourth scan unit 323 is for scanning I _m1 As a scanning center, with I _DAC For scanning step length, performing current scanning by adopting a self-increasing and self-decreasing algorithm to adjust the working current of the semiconductor laser; the fifth scanning unit 324 is used for scanning the range [ I ₁₂ ,I _m1 ]And a scanning range [ I _m1 ,I ₂₂ ]In coarse scanning steps I _c Duration of scan [0, T/2]Respectively carrying out current scanning in a target scanning range, and adjusting the working current of the semiconductor laser;

a third error comparing unit 316, configured to compare a fourth error of the working curve and the calibration curve of the semiconductor laser after the fifth scanning unit with a third error threshold;

a fourth calling unit 317, configured to call a sixth scanning unit when the fourth error is greater than a third error threshold;

the sixth scanning unit 325 is used for scanning the range [ I ₁₂ ,I _m1 ]And scanning Range [ I _m1 ,I ₂₂ ]In fine scanning steps I _s Duration of scan [ T/2, T]Respectively carrying out fine scanning in a target scanning range, and adjusting the working current of the semiconductor laser; wherein, I _c +I _s ＝2I _scan2 ，I _DAC ≤I _s <I _scan2 <I _c <2I _scan2 ；

A fourth error comparing unit 318 for comparing the magnitude of the fifth error and the third error threshold of the working curve and the calibration curve of the semiconductor laser after the sixth scanning unit, and comparing Δ I and I when the fifth error is less than or equal to the third error threshold _DAC Δ I = | I _m2 -I _m1 |，I _m2 The current working current of the semiconductor laser is;

a fifth calling unit 319, configured to call if Δ I is less than or equal to I _DAC When the delta I is larger than I, the parameter storage module is called _DAC A seventh scanning unit is called;

the seventh scanning unit 326 is used for scanning the fine scanning step I _s Is reduced by one I _DAC In the scanning range [ I ] ₁₂ ,I _m1 ]And scanning Range [ I _m1 ,I ₂₂ ]In the same way, the scanning duration [ T/2]Performing fine scanning, and adjusting the working current of the semiconductor laser until the semiconductor laser meets the preset condition;

the preset conditions comprise I _s ＝I _DAC Or | I _m3 -I _m2 |≤I _DAC ，I _m3 And when the error between the working curve and the calibration curve of the semiconductor laser acquired by the signal processor after fine scanning adjustment is less than or equal to a third error threshold value, the working current corresponding to the central wavelength of the output laser of the semiconductor laser.

The semiconductor laser can comprise any one of a distributed feedback laser, a distributed Bragg reflection laser, a vertical cavity surface emitting laser and an external cavity laser;

the distributed feedback laser, namely DFB, has built-in Bragg grating, the semiconductor laser that belongs to the side emission, DFB laser has very good monochromaticity (namely spectral purity), its existing money can be generally made within 1MHz, and have very high Side Mode Suppression Ratio (SMSR), it is at present as high as more than 40-50 dB;

distributed bragg reflector lasers, i.e. DBRs, lasers that use a distributed bragg reflector as a mirror, DBRs being different from DFBs, the entire active medium of the latter being placed in a distributed reflective structure;

a vertical cavity surface emitting laser, which is a semiconductor, the laser of which is emitted perpendicularly to the top surface, is different from the edge-emitting laser which is generally made of a cut independent chip and emitted from the edge;

the external cavity laser has the advantages of narrow line width, high output power and wide tuning range, and has the basic structure that the reflector and the gain device are used as the resonant cavity of the basic work of the laser, and the filtering element is inserted in the middle for mode selection, so that the single longitudinal mode laser output is realized.

In some embodiments, the semiconductor laser is a DFB laser, the signal processor is a signal processing center, and the implementing step includes:

firstly, calibrating a device, measuring a DFB laser by a spectrometer, and demodulating by a TDLAS system to obtain a calibration relation curve of a 2f/f normalization curve at a corresponding specific temperature;

controlling the current and temperature of the DFB laser during working through a temperature controller and a current controller, outputting laser with a specific wavelength, detecting the wavelength of the output laser through a photoelectric detector, and transmitting the collected signals into a signal processing center;

acquiring a low-frequency current error signal when the DFB laser works through current low-frequency scanning, and comparing the low-frequency current error signal with feedback information acquired by a peripheral received signal processing center through calibration information, wherein the low-frequency current error signal and the feedback information form a first re-feedback loop to transmit a current adjusting signal into a PID and approximation algorithm processing center, and the first re-feedback current fine-tuning signal and current setting form a second re-feedback loop to perform current micro-compensation on small-amplitude fluctuation of the wavelength of the DFB laser and improve the wavelength stability of the DFB laser;

the temperature micro-control processing center acquires a temperature signal of a DFB laser tube core, and the signal processing center inputs the temperature signal into the signal processing center for processing, so that the temperature compensation is carried out on the wavelength large fluctuation of the DFB laser, and the wavelength stability of the DFB laser is improved.

In an embodiment of the present invention, there is also provided a DFB laser wavelength specific time dynamic frequency stabilization technique for a TDLAS system, including the following steps:

1. the DFB laser component is powered on and started up respectively at the temperature T ₀ And current I ₀ Controlling the DFB laser to work normally;

2. initial calibration: working temperature T of DFB laser during calibration information calibration in earlier stage _m0 And operating current I _m0 The input temperature control circuit and the current circuit control the DFB laser to work normally; the signal processing center obtains the normalization curve of 2f/f by demodulation and compares the normalization curve with the calibration curve to analyze the error by 5 percent>δ>3%, performing fine adjustment calibration;

3. the signal processing center obtains a normalization curve and a calibration curve of the 2f/f through demodulation to analyze the error delta>5%, recalibration is required; low frequency scanning the DFB laser drive current for 2T, initial scanning range [ I ] ₁ ,I ₂ ]Re-acquiring the working current corresponding to the central wavelength through an approximation algorithm;

4. and (3) temperature micro-calibration: respectively carrying out fine adjustment on the temperature and the current according to the error magnitude obtained by the signal processing center;

5. for temperature T if the error is large ₁ Fine tuning to T ₂ Performing the temperature micro-calibration again;

6. comparing the final error value with the center of the signal, and comparing the temperature value T at the moment _m And a current value I _m Adjusting scanning step length I _scan Storing and transmitting the data into a frequency stabilization system;

7. the frequency stabilizing system will regulate the temperature T _m And current I _m The temperature control module and the current control module are introduced to realize stable drive control of the DFB laser, and the signal processing center compares signals every 2 minutes at the same time, so that calibration is realized, and continuous current is realizedMicro-adjusting;

and repeating the steps 3-7 to complete closed-loop control, realize the problems of dynamic calibration and frequency stability of the wavelength of the DFB laser, and realize that the laser wavelength output by the DFB laser at the T moment is the preset wavelength.

As will be appreciated by one skilled in the art, embodiments of the present application may be provided as a method, system, or computer program product. Accordingly, the present application may take the form of an entirely hardware embodiment, an entirely software embodiment or an embodiment combining software and hardware aspects. Furthermore, the present application may take the form of a computer program product embodied on one or more computer-usable storage media (including, but not limited to, disk storage, CD-ROM, optical storage, and the like) having computer-usable program code embodied therein.

The present application is described with reference to flowchart illustrations and/or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the application. It will be understood that each flow and/or block of the flowchart illustrations and/or block diagrams, and combinations of flows and/or blocks in the flowchart illustrations and/or block diagrams, can be implemented by computer program instructions. These computer program instructions may be provided to a processor of a general purpose computer, special purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, create means for implementing the functions specified in the flowchart flow or flows and/or block diagram block or blocks.

These computer program instructions may also be stored in a computer-readable memory that can direct a computer or other programmable data processing apparatus to function in a particular manner, such that the instructions stored in the computer-readable memory produce an article of manufacture including instruction means which implement the function specified in the flowchart flow or flows and/or block diagram block or blocks.

These computer program instructions may also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer implemented process such that the instructions which execute on the computer or other programmable apparatus provide steps for implementing the functions specified in the flowchart flow or flows and/or block diagram block or blocks.

It should be understood that the above examples are only for clarity of illustration and are not intended to limit the embodiments. Other variations and modifications will be apparent to persons skilled in the art in light of the above description. This need not be, nor should it be exhaustive of all embodiments. And obvious variations or modifications derived therefrom are intended to be within the scope of the invention.

Claims

1. A specific time laser wavelength control method based on TDLAS technology is characterized by comprising the following steps:

the method comprises the steps that an existing standard spectrum instrument is used for testing a semiconductor laser in advance to obtain the output characteristic of the semiconductor laser, and parameter information corresponding to the semiconductor laser is obtained based on a preset wavelength, wherein the parameter information comprises but is not limited to a calibration curve, a reference working temperature and a reference working current;

and if the error is less than or equal to the first error threshold value, adjusting the working current of the semiconductor laser by using a current controller, and adjusting the scanning step length according to the working current, so that the semiconductor laser outputs laser with a preset wavelength at a specific moment in the TDLAS system.

2. The TDLAS technology based time-specific laser wavelength control method of claim 1 wherein the obtaining the error of the working curve and the calibration curve using a signal processor comprises:

3. The TDLAS technology-based laser wavelength control method at a specific moment as set forth in claim 1, wherein the obtaining parameter information corresponding to the semiconductor laser based on the preset wavelength comprises:

and acquiring a reference working temperature and a reference working current which correspond to the central wavelength of the semiconductor laser at a preset wavelength at a specific moment in the TDLAS system based on the first corresponding relation and the second corresponding relation.

4. The TDLAS technology-based laser wavelength control method at a specific time as set forth in claim 1, wherein if the error is less than or equal to a first error threshold, adjusting an operating current of the semiconductor laser by using a current controller, and adjusting a scanning step according to the operating current, so that the semiconductor laser outputs laser light at a preset wavelength at a specific time in the TDLAS system comprises:

5. The TDLAS-technology-based specific-time laser wavelength control method as claimed in claim 4, wherein if the error is less than or equal to a first error threshold, adjusting the operating current of the semiconductor laser by using a current controller, and adjusting the scanning step according to the operating current, so that the semiconductor laser outputs the laser with the preset wavelength at the specific time in the TDLAS system further comprises:

if the error is greater than the second error threshold and less than or equal to the first error threshold, scanning the range [ I ] based on an approximation algorithm ₁ ,I ₂ ]And a scanning duration of 2T, with a scanning step length I _scan1 ＝(I ₂ -I ₁ ) Performing current scanning at 2T, adjusting the working current of the semiconductor laser, acquiring a third error of the current working curve and the calibration curve by using a signal processor, and comparing the third error with each errorThe size of the threshold;

if the third error is less than or equal to a third error threshold, acquiring a working current I corresponding to the center wavelength of the current output laser of the semiconductor laser _m1 In 1 with _m1 For the scan center, determine the scan range [ I ] ₁₂ ,I ₂₂ ]Current scanning is carried out on the semiconductor laser, and the working current of the semiconductor laser is adjusted;

wherein, I ₁₂ ≥I ₁ ,I ₂₂ ≤I ₂ 。

6. TDLAS technology based time-specific laser wavelength control method as claimed in claim 5, characterized in that I is _m1 For the scan center, determine the scan range [ I ₁₂ ,I ₂₂ ]And current scanning the semiconductor laser, wherein adjusting the operating current of the semiconductor laser comprises:

If the average scanning step length I _scan2 Less than the current resolution I of the semiconductor laser _DAC At the current resolution I _DAC As a scanning step with said operating current I _m1 Adopting a self-increasing and self-decreasing algorithm to carry out current scanning for a scanning center, and adjusting the working current of the semiconductor laser;

if the average scanning step length I _scan2 Current resolution I greater than or equal to that of semiconductor laser _DAC In the scanning range [ I ] ₁₂ ,I _m1 ]And scanning Range [ I _m1 ,I ₂₂ ]And respectively performing current scanning as target scanning ranges to adjust the working current of the semiconductor laser.

7. The TDLAS technology-based time-specific laser wavelength control method of claim 6, wherein the scan-by-scan method is used for controlling the laser wavelengthDescription of the Range [ I ₁₂ ,I _m1 ]And a scanning range [ I _m1 ,I ₂₂ ]Respectively as the target scanning scope to carry out current scanning, and the adjustment of the working current of the semiconductor laser comprises the following steps:

in coarse scanning step length I _c Duration of scan [0, T/2]Respectively carrying out coarse scanning in the target scanning range, and adjusting the working current of the semiconductor laser;

if the fourth error is larger than the third error threshold, using the fine scanning step length I _s Duration of scan [ T/2, T]Respectively carrying out fine scanning in a target scanning range, and adjusting the working current of the semiconductor laser;

8. The TDLAS technique based laser wavelength control method as claimed in claim 7, wherein if the fourth error is larger than the third error threshold, the fine scanning step I is used _s Duration of scan [ T/2, T]Respectively carrying out fine scanning in a target scanning range, and adjusting the working current of the semiconductor laser comprises the following steps:

if Δ I>I _DAC Then the value of the fine scanning step length is I _s Each time one I is reduced _DAC Performing one fine scanning operation, and adjusting the working current of the semiconductor laser until the semiconductor laser meets a preset condition;

9. A TDLAS technology based specific time laser wavelength control apparatus, which implements the TDLAS technology based specific time laser wavelength control method as claimed in any one of claims 1-8, comprising:

a TDLAS system, comprising:

a semiconductor laser;

the industrial computer for obtain the working curve that signal processor calculated and the error of calibration curve and semiconductor laser's operating current, and will the error is compared with the error threshold value, through operating current with the result of comparison of error and error threshold value calculates and obtains current feedback signal output to the current controller in order to adjust semiconductor laser's operating current, and according to operating current adjustment scanning step length makes the laser of realizing the output preset wavelength of specific moment semiconductor laser in the TDLAS system.

10. The TDLAS technology-based laser wavelength at a specific time control apparatus as claimed in claim 9, wherein the industrial computer comprises: