A detection method and system for measuring residual oxygen concentration by laser

Abstract

The application relates to a detection method and system for measuring residual oxygen concentration by laser, and relates to the field of gas concentration detection. The method comprises the following steps: selecting laser with oxygen absorption peak wavelength as detection laser, applying a periodically changed modulation signal to form a modulation laser and irradiate the headspace, demodulating a direct current component from the modulation laser passing through the headspace, calculating a deviation rate according to the direct current component and a reference direct current, judging whether the deviation rate is within a threshold value, feeding back and adjusting the laser wavelength if the deviation rate is not within the threshold value, and finally outputting a laser intensity attenuation curve of residual oxygen to obtain the residual oxygen concentration. The detection system comprises an optical subsystem, an electrical subsystem, a feedback control subsystem and a data processing subsystem. The application can accurately measure the residual oxygen concentration in the headspace, effectively detect and correct the laser wavelength drift, and improve the measurement precision and stability.

Description

Technical Field

[0001] This application relates to the field of laser gas detection equipment technology, and in particular to a laser method and system for measuring residual oxygen concentration. Background Technology

[0002] To determine whether residual oxygen content affects the reagents, the oxygen content in the top space of a reagent bottle is detected. Currently, lasers are generally used to detect the oxygen content in the top space.

[0003] The existing detection method involves irradiating the top space with a laser of a specific wavelength (760nm) where oxygen absorption peaks. The laser beam passing through the top space is then detected using a detector, generating a laser intensity attenuation curve. This curve is then combined with the selective absorption law of oxygen to a specific wavelength of laser light (Lambert-Beer Law) to determine the oxygen content in the top space. However, the laser wavelength is affected by the detection environment, leading to variations in the wavelength and consequently reducing the accuracy of the oxygen content detection results. Summary of the Invention

[0004] To address the issue that the accuracy of oxygen content detection results is reduced due to variations in laser wavelength caused by the detection environment, this application provides a laser method and system for measuring residual oxygen concentration.

[0005] The laser measurement method and system for residual oxygen concentration provided in this application adopt the following technical solution:

[0006] A laser measurement method for residual oxygen concentration includes the following steps:

[0007] S1. A laser with an oxygen absorption peak wavelength of λ0 is selected as the detection laser;

[0008] S2. Apply a periodically changing modulation signal to the detection laser to form a modulated laser;

[0009] S3. Irradiate the top space with modulated laser;

[0010] S4. Receive the modulated laser light passing through the top space and demodulate the DC component V of the modulated signal. DC ;

[0011] S5. Based on the demodulated DC component V DC With accurate wavelength reference DC V DC0 Calculate the deviation rate δ, δ=(V DC -V DC0 ) / V DC0 ×100%, set the threshold X of the deviation rate δ, and determine whether δ≤X. If yes, proceed to step S7; otherwise, proceed to step S6.

[0012] S6. Feedback adjusts the wavelength λ0 of the laser so that δ≤X;

[0013] S7. Output the laser intensity attenuation curve of residual oxygen and obtain the residual oxygen concentration in the top space.

[0014] By adopting the above technical solution, a laser with an oxygen absorption peak wavelength of λ0 is selected as the detection laser. A modulation signal is applied to form a modulated laser, which is then used to illuminate the top space. The DC component V is received and demodulated. DC The deviation rate δ is calculated and compared with the threshold X. If the deviation rate exceeds the threshold, the laser wavelength is adjusted to ensure that the deviation rate meets the requirements. Then, the laser intensity attenuation curve of residual oxygen is output and the residual oxygen concentration is obtained. This can reduce the laser wavelength drift caused by temperature, ensure the accuracy of the laser wavelength, and thus improve the accuracy of residual oxygen concentration measurement.

[0015] Preferably, in step S2, a sinusoidal signal is applied to the detection laser through an electro-optic modulator to form a modulated laser.

[0016] By adopting the above technical solution, a sinusoidal signal is applied to the detection laser using an electro-optic modulator to form a modulated laser, which enables the laser to have periodic variation characteristics, facilitating subsequent demodulation operations. This provides a basis for accurately calculating the deviation rate and adjusting the laser wavelength, thereby ensuring the accuracy of residual oxygen concentration measurement.

[0017] Preferably, in step S4, the modulated laser signal is demodulated using a synchronous multiplier module. The inputs of the synchronous multiplier module include the modulated laser signal and the sinusoidal signal applied by the electro-optic modulator. After passing through a low-pass filter, the output is the DC component V. DC .

[0018] By adopting the above technical solution, a multiplier is used to demodulate the modulated laser signal, and a low-pass filter is used to output the DC component V. DC This provides an accurate data basis for subsequent calculation of deviation rate, determination of whether laser wavelength has drifted, and feedback adjustment of laser wavelength, thereby improving the accuracy of residual oxygen concentration measurement.

[0019] Preferably, in step S5, the microcontroller acquires V at a sampling frequency of 100Hz. DC Ten sets of data were collected consecutively. After removing the maximum and minimum values, the average value was taken to obtain V. DC-avg V DC-avg Substitute the values ​​into the formula for the deviation rate δ for calculation.

[0020] By adopting the above technical solution, VDC is collected at a sampling frequency of 100Hz and 10 sets of data are taken. After removing the maximum and minimum values, the average value is taken, which can reduce the impact of abnormal data on the deviation rate calculation and make the calculated deviation rate more accurately reflect the actual drift of the laser wavelength, thereby further improving the accuracy of residual oxygen concentration measurement.

[0021] Preferably, the laser wavelength drift is estimated based on the calculated deviation rate. The estimation method is as follows: by calibrating a standard curve of deviation rate δ and laser wavelength drift Δλ through previous experiments, the calculated deviation rate δ is substituted into the δ-Δλ standard curve to obtain the laser wavelength drift. The threshold X of deviation rate δ includes graded thresholds X1 and X2. Let the graded thresholds of laser wavelength drift be Y1 and Y2, and Y2>Y1. The degree of wavelength drift is judged based on Δλ. The judgment criteria are: if Δλ≤Y1 and δ≤X1, there is no drift; if Y1<Δλ≤Y2 and X1<δ≤X2, there is slight drift; if Y2<Δλ and X2<δ, there is severe drift.

[0022] By adopting the above technical solution, the drift of the laser wavelength is estimated based on the calculated deviation rate. By combining the grading threshold of the deviation rate with the grading threshold of the laser wavelength drift, the degree of laser wavelength drift can be accurately determined, providing a basis for subsequent targeted feedback adjustment of the laser wavelength and further improving the accuracy of residual oxygen concentration measurement.

[0023] Preferably, in step S6, when the laser wavelength drifts slightly, the PID controller compares the current laser temperature with the target temperature in real time and outputs a PWM signal to control the TEC to cool / heat until δ≤X1.

[0024] By adopting the above technical solution, when the laser wavelength experiences a slight drift, the PID controller compares the temperature in real time and outputs a PWM signal to control the TEC cooling / heating. This allows for precise and timely feedback adjustment of the laser wavelength, ensuring the deviation rate remains within the required range. This avoids the significant impact of temperature-induced laser wavelength drift on the residual oxygen concentration measurement, further improving the stability and reliability of the residual oxygen concentration measurement results.

[0025] Preferably, when the laser wavelength drifts severely, δ is first reduced to X1 < δ ≤ X2 through TEC, and then the driving current of the laser is adjusted so that δ ≤ X1.

[0026] By adopting the above technical solution, when the laser wavelength drifts severely, the deviation rate can be reduced to a certain range using TEC first, and then the laser drive current can be adjusted. This allows for effective phased correction of the laser wavelength, ensuring its accuracy and thus improving the precision and reliability of residual oxygen concentration measurement.

[0027] Preferably, in step S6, a verification of the correction effect is added, and 20 sets of V data are continuously collected after correction. DC-avg If all data satisfy δ≤X, the correction is considered valid; otherwise, the correction is considered invalid.

[0028] By adopting the above technical solution, adding verification of the correction effect in the correction step of feedback adjustment of laser wavelength can ensure the effectiveness of laser wavelength correction, avoid inaccurate residual oxygen concentration measurement results due to ineffective correction, and further improve the reliability of residual oxygen concentration measurement.

[0029] A laser-based residual oxygen concentration detection system, using the aforementioned laser-based residual oxygen concentration detection method, includes an optical subsystem, an electrical subsystem, a feedback control subsystem, and a data processing subsystem. The electrical subsystem processes signals from the optical subsystem, the feedback control subsystem provides feedback control over the laser wavelength, and the data processing subsystem processes the data.

[0030] By adopting the above technical solution, the system uses a detection method that includes selecting a specific wavelength for laser detection, applying a modulation signal to form a modulated laser, illuminating the top space, demodulating the DC component, calculating the deviation rate to determine wavelength drift, and providing feedback adjustment. Combined with the collaborative work of the optical subsystem, electrical subsystem, feedback control subsystem, and data processing subsystem, the system can reduce the amount of laser wavelength drift caused by temperature, ensure the accuracy of the laser wavelength, and thus improve the accuracy of residual oxygen concentration measurement.

[0031] Preferably, the optical subsystem includes a DFB laser, an electro-optic modulator, and a photodetector. The DFB laser is capable of outputting a narrow-linewidth laser with the oxygen absorption peak wavelength. The electro-optic modulator is capable of applying sinusoidal amplitude modulation to the laser. The photodetector is capable of receiving the laser transmitted through the top space and converting it into an electrical signal.

[0032] By adopting the above technical solution, the DFB laser outputs a narrow-linewidth laser with the oxygen absorption peak wavelength, the electro-optic modulator applies sinusoidal amplitude modulation to the laser, and the photodetector receives the laser transmitted through the top space and converts it into an electrical signal. This provides a suitable signal for subsequent operations such as demodulating the modulated laser, calculating the deviation rate, and judging the laser wavelength drift, thereby ensuring the smooth progress of the residual oxygen concentration measurement process and improving the accuracy of the residual oxygen concentration measurement.

[0033] In summary, this application includes at least one of the following beneficial technical effects:

[0034] 1. By applying a modulation signal to the detection laser to form a modulated laser, receiving the modulated laser and demodulating the DC component to calculate the deviation rate, and adjusting the laser wavelength based on the deviation rate feedback, the laser wavelength drift caused by the detection environment can be reduced.

[0035] 2. By using feedback to adjust the laser wavelength, the accuracy of the laser wavelength can be ensured, regardless of the detection environment.

[0036] 3. Ensuring accurate laser wavelength can improve the accuracy of residual oxygen concentration measurement and meet the requirements of high-precision measurement. Attached Figure Description

[0037] Figure 1 This is a flowchart of a laser-based detection system for measuring residual oxygen concentration, according to an embodiment of this application.

[0038] Figure 2 This is a flowchart of a laser measurement method for detecting residual oxygen concentration according to an embodiment of this application.

[0039] Explanation of reference numerals in the attached figures: 11, DFB laser; 12, electro-optic modulator; 13, photodetector; 21, signal generator; 22, synchronous multiplier module; 23, low-pass filter; 31, PID controller; 32, TEC temperature controller; 33, laser drive current source; 41, microcontroller; 42, display module; 5, glass bottle sample cell; 51, top space. Detailed Implementation

[0040] The following will be combined with the appendix Figures 1-2 The technical solutions in the embodiments of the present invention are further described in detail below. The described embodiments are only possible technical implementations of the present invention, but are not limited thereto. Those skilled in the art can certainly combine the embodiments of the present invention to obtain other embodiments without creative effort, which are also within the protection scope of the present invention.

[0041] This application mainly uses the method of applying a modulation signal to form a detection band and calculating the actual wavelength to measure oxygen content, which achieves the effect of avoiding the influence of laser wavelength drift and improving the accuracy of oxygen concentration detection. The following is a further detailed description of this application.

[0042] Reference Figure 1 A laser-based detection system for measuring residual oxygen concentration includes an optical subsystem, an electrical subsystem, a feedback control subsystem, and a data processing subsystem.

[0043] The optical subsystem includes a DFB laser 11, an electro-optic modulator 12, and a photodetector 13. The DFB laser 11 has an output power of 5mW, a linewidth of <0.01nm, and outputs a narrow-linewidth laser with an oxygen absorption peak wavelength λ0=760nm. The electro-optic modulator 12 uses a LiNbO3 crystal, with a modulation frequency of 1~100kHz and an insertion loss of <3dB, to modulate the detection laser into a modulated laser. A top space 51 is formed at the top of the glass bottle sample cell 5 to ensure that there is no significant attenuation when the laser passes through the top space 51. The photodetector 13 uses a silicon-based PIN diode with a response wavelength of 400~1100nm and a dark current of <1nA. It receives the modulated laser transmitted through the sample cell and converts it into an electrical signal.

[0044] The electrical subsystem includes a signal generator 21, a synchronous multiplier module 22, and a low-pass filter 23. The signal generator 21 is a function signal generator that outputs a 10kHz sine wave with an amplitude of 0–5V, providing a modulation reference signal for the EOM and synchronizing it to the synchronous multiplier module 22. The synchronous multiplier module 22 is an integrated operational amplifier with a bandwidth of 1MHz and a linearity of ±0.1%, performing multiplication of the modulated signal and the received signal. The low-pass filter 23 uses an active LPF with a cutoff frequency of 1kHz and an attenuation rate of 80dB / decade, filtering out the second harmonic component and extracting the DC component V. DC .

[0045] The feedback control subsystem includes a PID controller 31, a TEC temperature controller 32, and a laser drive current source 33. The PID controller 31 uses a digital PID with a sampling frequency of 100Hz and an adjustment accuracy of ±0.01V. It can calculate the deviation rate δ and output adjustment commands. The TEC temperature controller 32 has an accuracy of ±0.01℃ and a temperature control range of -10~60℃. It adjusts the laser temperature and suppresses wavelength drift. The laser drive current source 33 outputs a constant current of 0~500mA with a ripple of <1μA. It is used to assist in adjusting the laser wavelength and supplement the deficiencies of temperature control.

[0046] The data processing subsystem includes a microcontroller 41 (MCU) and a display module 42. The MCU adopts a 32-bit ARM architecture, with a main frequency of 100MHz and an AD sampling precision of 12 bits, and is used to acquire V. DC It calculates oxygen concentration and stores data; the display module 42 is an OLED screen that displays oxygen concentration, wavelength drift status, and system parameters in real time.

[0047] This application also discloses a method for detecting residual oxygen concentration using laser measurement.

[0048] Reference Figure 2 A laser measurement method for residual oxygen concentration includes the following steps:

[0049] S1. Select a laser with an oxygen absorption peak wavelength of λ0 as the detection laser. Start the DFB laser 11, which generates a detection laser with a wavelength of 760nm.

[0050] S2. A periodically varying modulation signal is applied to the detection laser to form a modulated laser. The electro-optic modulator 12 applies a sinusoidal modulation signal to the detection laser. The modulation signal is an AC signal with a frequency of 10kHz and an amplitude of 3V, which forms a modulated laser after modulation.

[0051] S3. The modulated laser is used to irradiate the top space 51. When the modulated laser is used to irradiate the top space 51 inside the glass bottle, oxygen absorbs part of the laser energy.

[0052] S4. Receive the modulated laser light passing through the top space 51 and demodulate the DC component V of the modulated signal. DC The photodetector 13 receives the modulated laser light passing through the top space 51 of the glass bottle and converts the optical signal of the modulated laser light into an electrical signal. The modulated laser signal and the sinusoidal signal applied by the electro-optic modulator 12 are used as the input signals of the synchronous multiplier module 22. The signal at the output of the synchronous multiplier module 22 is passed through the low-pass filter 23 and outputs the DC component V. DC .

[0053] S5. Based on the demodulated DC component V DC With accurate wavelength reference DC V DC0 Calculate the deviation rate δ, δ=(V DC -V DC0 ) / V DC0 ×100%, set the threshold X of the deviation rate δ, and determine whether δ≤X. If yes, proceed to step S7; otherwise, proceed to step S6.

[0054] In V DC When determining the value, the microcontroller 41 acquires V at a sampling frequency of 100Hz. DC Ten sets of data were collected consecutively. After removing the maximum and minimum values, the average value was taken to obtain V. DC-avg V DC-avg Substituting the formula for calculating the deviation rate, we get δ=(V DC-avg -V DC0 ) / V DC0 ×100%, V is collected at a sampling frequency of 100Hz. DC Ten sets of data were taken, and the maximum and minimum values ​​were removed before taking the average value. This reduces the impact of abnormal data on the deviation rate calculation, making the calculated deviation rate more accurately reflect the actual drift of the laser wavelength, thereby further improving the accuracy of residual oxygen concentration measurement.

[0055] The threshold X of the deviation rate δ includes graded thresholds X1 and X2. In this embodiment, X1=3% and X2=8%. After calculating the deviation rate δ, in order to improve the adjustment efficiency and accuracy of the laser wavelength adjustment of the DFB laser 11, the standard curve of the deviation rate δ and the laser wavelength drift Δλ is first calibrated through previous experiments and stored in the MCU. The δ-Δλ calibration curve is obtained by the following steps:

[0056] 1. Adjust the temperature and current of the laser source, and observe the laser wavelength using a wavelength meter until the wavelength stabilizes at the center of the 760nm oxygen absorption peak.

[0057] 2. Maintain a stable laser wavelength (Δλ=0) and allow the MCU to continuously acquire 100 sets of V. DC The data, after being averaged, is used as the baseline value V. DC0 Calculate the δ value at this time (theoretically δ=0, but in reality it may be within ±0.2% due to noise, so take the average and record it as δ0=0), and use it as the δ reference point corresponding to Δλ=0;

[0058] 3. Control the wavelength drift by "adjusting the laser source temperature" (temperature control is preferred because it has better linearity between temperature and wavelength and higher adjustment accuracy), and collect data in the order of "Δλ gradually increasing from 0 to 0.025nm".

[0059] 4. Remove outliers from the data and calculate the average value to obtain the "Δλ-average δ" correspondence table. Since the relationship between δ and Δλ conforms to the Lorentz line type, a nonlinear fitting model is adopted. The parameters of the fitting formula are stored in the MCU's Flash memory for subsequent "inverse deduction of Δλ through δ" calls.

[0060] 5. Reliability verification: Select 3-5 Δλ points that are not involved in the fitting, manually adjust the laser wavelength to this value, record the measured δ, substitute the measured δ into the fitting formula, calculate the back-inferred Δλ, and compare it with the measured Δλ of the wavelength meter. The error should be ≤0.002nm.

[0061] The deviation rate δ is used to calculate Δλ based on the δ-Δλ calibration curve. Let the threshold values ​​for the laser wavelength drift Δλ be Y1 and Y2, where Y1 = 0.005 nm and Y2 = 0.015 nm. The degree of wavelength drift is determined based on δ and Δλ, specifically as follows:

[0062] If Δλ≤0.005nm and δ≤3%, then there is no drift;

[0063] If 0.005nm < Δλ ≤ 0.015nm and 3% < δ ≤ 8%, then there is a slight drift.

[0064] If 0.015nm < Δλ and 8% < δ, then there is severe drift.

[0065] S6. Feedback adjusts the wavelength λ0 of the laser so that δ≤X.

[0066] There are two ways to adjust the laser wavelength. One is the TEC temperature controller 32. The principle of the TEC temperature controller 32 is based on the wavelength-temperature coefficient of the DFB laser 11 being 0.1 nm / ℃. By changing the temperature of the DFB laser 11, the wavelength of the laser is adjusted.

[0067] Another type is the laser-driven current source 33, whose driving current wavelength adjustment principle is based on the "carrier concentration-refractive index correlation effect" of semiconductor lasers.

[0068] When the laser wavelength drifts slightly, the PID controller 31 compares the current laser temperature with the target temperature in real time and outputs a PWM signal to control the TEC cooling / heating. Specifically, the PID controller 31 uses proportional (P) + integral (I) control to convert Δλ into the "target temperature adjustment amount ΔT". The PID controller 31 compares the current laser temperature with the target temperature in real time and outputs a PWM signal to control the TEC cooling / heating until δ returns to δ≤3%.

[0069] When the laser wavelength drifts significantly, first reduce δ to 3% < δ ≤ 8% through TEC, and then adjust the laser drive current to make δ ≤ 3%.

[0070] After calibration, 20 sets of V samples were continuously collected. DC-avg If all data satisfy δ≤X, the correction is considered valid; otherwise, the correction is considered invalid.

[0071] S7, the display module 42 outputs the laser intensity attenuation curve of residual oxygen and reads the residual oxygen concentration in the top space 51.

[0072] The implementation principle of the laser measurement method for residual oxygen concentration in this application embodiment is as follows: a laser with an oxygen absorption peak wavelength of 760nm is selected as the detection laser, a modulation signal is applied to form a modulated laser and irradiates the top space 51, and the DC component V is received and demodulated. DC The deviation rate δ is calculated and compared with the threshold of 3%. If the deviation rate exceeds the threshold, the laser wavelength is adjusted to ensure that the deviation rate meets the requirements. Then, the laser intensity attenuation curve of residual oxygen is output and the residual oxygen concentration is obtained. This can reduce the laser wavelength drift caused by temperature, ensure the accuracy of the laser wavelength, and thus improve the accuracy of residual oxygen concentration measurement.

[0073] The above are all preferred embodiments of this application, and are not intended to limit the scope of protection of this application. Therefore, all equivalent changes made in accordance with the structure, shape and principle of this application should be covered within the scope of protection of this application.

Claims

1. A method for detecting residual oxygen concentration using laser measurement, characterized in that: Includes the following steps: S1. A laser with an oxygen absorption peak wavelength of λ0 is selected as the detection laser; S2. Apply a periodically changing modulation signal to the detection laser to form a modulated laser; S3, Illuminate the top space with the modulated laser (51); S4. Receive the modulated laser light passing through the top space (51) and demodulate the DC component V of the modulated signal. DC ; S5. Based on the demodulated DC component V DC With accurate wavelength reference DC V DC0 Calculate the deviation rate δ, δ=(V DC -V DC0 ) / V DC0 ×100%, set the threshold X of the deviation rate δ, and determine whether δ≤X. If yes, proceed to step S7; otherwise, proceed to step S6. S6. Feedback adjusts the wavelength λ0 of the laser so that δ≤X; S7, output the laser intensity attenuation curve of residual oxygen, and obtain the residual oxygen concentration in the top space (51); In step S2, a sinusoidal signal is applied to the detection laser through the electro-optic modulator (12) to form a modulated laser; In step S5, the microcontroller (41) acquires V at a sampling frequency of 100Hz. DC Ten sets of data were collected consecutively. After removing the maximum and minimum values, the average value was taken to obtain V. DC-avg V DC-avg Substitute the values ​​into the formula for the deviation rate δ for calculation; The laser wavelength drift is estimated based on the calculated deviation rate. The estimation method is as follows: the standard curve of deviation rate δ and laser wavelength drift Δλ is calibrated through previous experiments, and the calculated deviation rate δ is substituted into the δ-Δλ standard curve to obtain the laser wavelength drift. The threshold X of the deviation rate δ includes graded thresholds X1 and X2. Let the graded thresholds for the laser wavelength drift be Y1 and Y2, where Y2 > Y1. The degree of wavelength drift is determined based on Δλ, and the criteria for determination are as follows: If Δλ≤Y1 and δ≤X1, then there is no drift; If Y1 < Δλ ≤ Y2 and X1 < δ ≤ X2, then there is a slight drift; If Y2 < Δλ and X2 < δ, then there is a severe drift.

2. The method for detecting residual oxygen concentration by laser measurement according to claim 1, characterized in that: In step S4, the modulated laser signal is demodulated using a synchronous multiplier module (22). The inputs of the synchronous multiplier module (22) include the modulated laser signal and the sinusoidal signal applied by the electro-optic modulator (12). After passing through a low-pass filter (23), the output is the DC component V. DC .

3. The method for detecting residual oxygen concentration by laser measurement according to claim 1, characterized in that: In step S6, when the laser wavelength drifts slightly, the PID controller (31) compares the current laser temperature with the target temperature in real time and outputs a PWM signal to control the TEC to cool / heat until δ≤X1.

4. The method for detecting residual oxygen concentration by laser measurement according to claim 3, characterized in that: When the laser wavelength drifts significantly, δ is first reduced to X1 < δ ≤ X2 through TEC, and then the laser drive current is adjusted to make δ ≤ X1.

5. The method for detecting residual oxygen concentration by laser measurement according to claim 1, characterized in that: In step S6, the calibration effect is verified by continuously collecting 20 sets of V data after calibration. DC-avg If all data satisfy δ≤X, the correction is considered valid; otherwise, the correction is considered invalid.

6. A laser-based detection system for residual oxygen concentration, using the laser-based method for residual oxygen concentration as described in any one of claims 1-5, characterized in that: It includes an optical subsystem, an electrical subsystem, a feedback control subsystem, and a data processing subsystem. The electrical subsystem processes the signals from the optical subsystem, the feedback control subsystem provides feedback control over the wavelength of the laser, and the data processing subsystem processes the data.

7. The laser-based residual oxygen concentration detection system according to claim 6, characterized in that: The optical subsystem includes a DFB laser (11), an electro-optic modulator (12), and a photodetector (13). The DFB laser (11) is capable of outputting a narrow-linewidth laser with the oxygen absorption peak wavelength. The electro-optic modulator (12) is capable of applying sinusoidal amplitude modulation to the laser. The photodetector (13) is capable of receiving the laser transmitted through the top space (51) and converting it into an electrical signal.

Images