Portable laser headspace oxygen analyzer and compensation algorithm

Abstract

The application discloses a portable laser headspace oxygen analyzer and a compensation algorithm, which comprises a light source module composed of a narrow-band tunable semiconductor laser and a laser shell structure piece, a laser control module, a packaged glass ampoule placement room, a photoelectric detection module, a high-precision signal acquisition and generation module, an FPGA parallel processing module, a man-machine interaction module and a power supply module. The laser control module comprises temperature control and current control, and two control ports are directly connected with laser terminals. The packaged glass ampoule placement room is used for placing a packaged glass ampoule to be measured. The photoelectric detection module comprises a photosensitive element and a photoelectric amplification circuit, and completes photoelectric signal conversion. The output of the photoelectric detection module is connected with a signal acquisition input end. The application realizes packaged glass ampoule headspace oxygen content analysis, and has strong compatibility and is convenient to carry.

Description

Technical Field

[0001] This invention relates to the field of gas measurement, and in particular to a portable laser headspace oxygen analyzer and its compensation algorithm. Background Technology

[0002] Sterile preparations are an important product form in the pharmaceutical industry, and their packaging quality directly determines the quality of the drug. Glass vials are widely used in the packaging of various preparations due to their ease of transportation, storage, and use. However, during the sealing and capping processes, oxygen from the air can enter the vial and cause drug deterioration. Therefore, analyzing the headspace oxygen content of sealed glass vials is crucial for assessing the sealing quality of sterile preparations.

[0003] Electrochemical and optical detection methods are commonly used for oxygen concentration analysis. Electrochemical detection is often a destructive method, and due to the wear and tear on the sensor caused by the chemical reaction, the instrument's lifespan is generally short. Optical detection, on the other hand, is a non-contact method that is not only fast and sensitive, but also has a longer instrument lifespan, making it a commonly used technology for headspace oxygen analyzers.

[0004] Commercially available headspace oxygen analyzers generally employ laser-induced fluorescence spectroscopy (DIFS) and tunable semiconductor laser absorption spectroscopy (TDLAS). Fluorescence detection is based on molecular energy level theory: ground-state molecules absorb energy and transition to excited states, while excited-state molecules release energy back to the ground state, producing fluorescence. Since gases with different structures absorb different wavelengths, the emitted fluorescence varies. Therefore, the composition and concentration of the analyte gas are analyzed by studying the optical information of the fluorescence. TDLAS detection, based on the Lambert-Beer law, determines the composition and concentration of the analyte gas by analyzing the absorption intensity of laser light at different concentrations at specific wavelengths.

[0005] The aforementioned optical detection technologies provide a solid technical foundation for the development of headspace oxygen analyzers. However, existing headspace oxygen analyzers still have many limitations. For example, the fluorescence-based headspace residual oxygen analyzer (patent CN211927703U) requires a fluorescent sheet to be placed on the surface of the object to be measured before measurement. Compared with headspace oxygen analyzers based on TDLAS technology, its measurement steps are relatively complex and its usability is poor. The headspace oxygen analyzer designed by patent CN307582406S still requires external power supply, has poor portability, and cannot be used without power when traveling. The internationally advanced headspace oxygen analyzer Gasporox has achieved high detection accuracy, but when measuring glass vials of different capacities, corresponding adapters need to be purchased, resulting in poor measurement compatibility. Summary of the Invention

[0006] In view of the above, the purpose of this application is to provide a portable laser headspace oxygen analyzer to achieve rapid and accurate measurement of headspace oxygen content in encapsulated glass medicine bottles, thereby solving the problem of quality inspection of penicillin bottle packaging in the pharmaceutical field.

[0007] To achieve the above objectives, the present invention provides the following solution: On the one hand, this application provides a portable laser headspace oxygen analyzer, including a light source module composed of a narrowband tunable semiconductor laser and a laser housing structure, a laser control module, a glass vial placement chamber, a photoelectric detection module, a high-precision signal acquisition and generation module, an FPGA parallel processing module, a human-machine interaction module, and a power supply module; The laser control module includes temperature control and current control, and the ports for temperature control and current control are directly connected to the laser terminals. The encapsulated glass medicine bottle placement chamber holds the encapsulated glass medicine bottle to be tested. The photoelectric detection module includes a photosensitive element and a photoelectric amplification circuit to complete the photoelectric signal conversion. The output terminal of the photoelectric detection module is connected to the signal acquisition input terminal. The high-precision signal acquisition and generation module includes a photoelectric signal acquisition module and a laser control signal generation module. The output end of the photoelectric signal acquisition module and the input end of the laser control signal generation module are connected to the FPGA, and the output end of the laser control signal generation module is connected to the input end of the laser controller. The FPGA parallel processing module is configured to perform spectral signal processing and oxygen concentration information inversion and transmit it to the human-computer interaction module. The human-computer interaction module includes a measurement interface and a debugging interface, which are responsible for displaying measurement results and debugging system parameters, respectively. The power supply module is powered by a lithium battery and is equipped with a voltage monitoring and alarm function.

[0008] Optionally, the light source module is compatible with both DFB-packaged and VCSEL-packaged lasers. The light source module allows the laser incident angle to be freely adjusted, and the light source module is equipped with an angle adjustment algorithm for self-adjustment of the laser incident angle.

[0009] Optionally, the encapsulated glass vial placement chamber is equipped with adjustable clamps for holding glass vials of different sizes, and is also configured with an adaptive measurement algorithm for the headspace oxygen content of encapsulated vials of different sizes.

[0010] Optionally, the FPGA parallel processing module includes a lock-in amplification module and a concentration inversion module for the absorption spectral signal.

[0011] Optionally, the FPGA parallel processing module is designed with a light intensity correction module based on the second harmonic divided by the DC term amplitude.

[0012] Optionally, the FPGA parallel processing module is configured to adaptively filter the second harmonic using an adaptive filtering algorithm.

[0013] Alternatively, on the other hand, this application provides a compensation algorithm for a portable laser headspace oxygen analyzer, including a self-adjusting algorithm for the optimal laser incident angle in the light source module, a wavelength range self-correction algorithm in the laser control module, an adaptive measurement algorithm for the headspace oxygen content of different packaged medicine bottles, and an adaptive filtering algorithm in the FPGA parallel processing module.

[0014] Optionally, the self-adjusting algorithm for the optimal laser incident angle is as follows: (1) When incident at a horizontal angle, the detection system is measured for a long time to obtain the peak value of the kth period of the second harmonic, which is the kth value of the upper envelope, i.e.

[0015] Under long-term measurement, the upper envelope of the second harmonic over M periods can be obtained. This envelope can be approximately fitted as:

[0016] Where T is the period of the laser modulation signal, a is the amplitude of the sinusoidal portion of the envelope, and bias is the offset. Ultimately, a can be used to evaluate the degree of beam interference at this point.

[0017] (2) Change the laser incident angle, re-measure the detection system for a long time, obtain the second harmonic peak value demodulated in the FPGA for a long time, obtain the upper envelope and fit it to obtain a new sine amplitude.

[0018] (3) Repeat operation (2) until the sinusoidal amplitude fitted by the envelope reaches the minimum, that is, the beam interference effect is suppressed to the minimum. The laser incident angle at this time is the optimal incident angle.

[0019] Optionally, the wavelength range self-correction algorithm in the laser control module is as follows: (1) Integrate the second harmonic peak finding algorithm in the FPGA to locate the position of the second harmonic center in the entire scanning band; (2) When the center of the second harmonic is located to the right of the entire scanning band, reduce the offset of the DDS signal generated by the FPGA; when the center of the second harmonic is located to the left of the entire scanning band, increase the offset of the DDS signal generated by the FPGA. (3) Repeat operation (2) until the second harmonic center is at the midpoint of the entire scanning range, and finally achieve the adaptive wavelength scanning range.

[0020] Optionally, the adaptive measurement algorithm for headspace oxygen content of medicine vials with different packaging specifications is as follows: Perform compensation operation on the second harmonic peak, , where m is the modulation coefficient, N is the concentration of the gas to be measured, L is the optical path, P is the current air pressure, S(T) is the absorption intensity, and I0 is the light intensity, is the second harmonic peak, is the compensated second harmonic peak, and d is the inner diameter of the glass vial to be measured.

[0021] Concentration fitting is performed on the compensated second harmonic peak and the corresponding headspace oxygen content, so as to obtain fitting curves of the headspace oxygen content of packaged glass vials of different specifications, and realize adaptive measurement of residual oxygen in different glass vials.

[0022] Optionally, the adaptive filtering algorithm in the FPGA parallel processing module is: (1) Calculate the second harmonic sidelobe peak:

[0023] (2) Average two adjacent sidelobe values to obtain a total of N sidelobe average peaks in N cycles; (N can be determined according to the laser scanning frequency, according to engineering experience, f<N<3.72f, where f is the scanning frequency)

[0024] (3) Calculate the normalized variance of the M sidelobe average peaks;

[0025] where e is the normalized variance, is the sample mean, is the sample standard deviation.

[0026] (4) The frequency inside the FPGA is scanned from 10kHz to 20kHz in steps of 100Hz, until the normalized variance of the sidelobe peak is minimized, which is the optimal modulation frequency fm of the current laser at this time.

[0027] (5) According to the optimal frequency, correct the number of differential link delays R of the CIC filter built in the FPGA, specifically, R=1.28fm / 100. Finally, adaptive filtering for the second harmonic is realized, and the system stability is improved.

[0028] In conclusion, due to the adoption of the above technical solutions, the beneficial effects of the present invention are as follows: This invention enables the analysis of headspace oxygen content in encapsulated glass medicine bottles, and is highly compatible and portable. The portable laser headspace oxygen analyzer provided by this invention enables accurate measurement of headspace oxygen content in encapsulated glass medicine bottles. This invention features an adjustable fixture and develops a measurement algorithm adapted to the headspace oxygen content of medicine bottles of different sizes, allowing for the measurement of headspace oxygen content in encapsulated penicillin medicine bottles of various sizes. This invention allows for self-adjustment of the laser incident angle, which helps to reduce the optical interference effects of medicine bottles of different sizes. This invention designs an optimal modulation frequency adaptive adjustment algorithm to optimize the filtering performance of the detection system. Attached Figure Description

[0029] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly described below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort. Figure 1 This is a schematic diagram of the instrument structure in this application; Figure 2 This is a general framework diagram of this application; Figure 3 This is a flowchart of the workflow for this application; Figure 4 This is a diagram illustrating the use of the clamp; Figure 5 Diagram showing laser replacement; Figure 6 This is a schematic diagram of the external connections of a laser-based headspace oxygen online analyzer. Detailed Implementation

[0030] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only for explaining the invention and are not intended to limit the invention; that is, the described embodiments are merely some embodiments of the invention, and not all embodiments. The components of the embodiments of the invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0031] Therefore, the following detailed description of the embodiments of the invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the invention without inventive effort are within the scope of protection of the invention.

[0032] It should be noted that relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0033] The technical solutions, principles, and products of the present invention will be fully described below with reference to the accompanying drawings. The described embodiments are only a part of the embodiments of the present invention, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0034] The purpose of this invention is to provide a portable laser headspace oxygen analyzer for detecting leakage in encapsulated glass medicine bottles in the pharmaceutical industry, thereby achieving accurate detection of the headspace oxygen content in encapsulated glass medicine bottles.

[0035] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments.

[0036] Example 1 This embodiment provides a laser headspace oxygen analyzer for 10mL vials. The instrument's mechanical structure is described below. Figure 1 The system includes: a light source module, a laser control module, a placement chamber, a photoelectric detection module, a high-precision signal acquisition and generation module, an FPGA parallel processing module, a human-machine interaction module, and a system power supply module. The overall system framework diagram is shown below. Figure 2 See workflow diagram Figure 3 .

[0037] Specifically, the light source module uses a VCSEL (Vertical Cavity Surface Emitting Laser) with a center wavelength of 760.8nm, an operating temperature range of -40℃ to 80℃, a stable output of 760~761.8nm laser light, an optical power of 1.5mW, a wavelength temperature sensitivity of 0.06nm / ℃, a wavelength current sensitivity of 0.5nm / mA, and a signal-to-noise ratio of 35dB. At the same time, mechanical structural components such as the laser base and housing are designed to allow for adjustment of the laser emission angle.

[0038] Specifically, a schematic diagram of the angle optimization algorithm can be found here. Figure 3 The specific implementation method is as follows: a. Set the laser to be incident at zero angle on the glass vial under test, and obtain the second harmonic peak envelope sequence over 93 periods, resulting in:

[0039] b. Sine-fit the above envelope sequence to obtain...

[0040] c. Adjust the laser incident angle, repeat steps a and b, and finally obtain... a The envelope with the smallest value yields the optimal incident angle of 10.5° for the current situation.

[0041] The VITC002 laser control module integrates TEC temperature control and LD current control: PID temperature control precisely controls the VCSEL laser's operating temperature at 24.4℃; LD current control injects a low-frequency ramp signal + a high-frequency sine wave drive current signal into the laser in CC mode (Constant Current) to achieve fine scanning of the laser's output wavelength, with a scanning band of 760.6nm~761nm. Combined with an adaptive algorithm for the wavelength scanning range, it can resist the scanning band drift problem caused by temperature drift of the laser and controller. Specifically, the wavelength scanning range adaptive algorithm is implemented as follows: The location of the second harmonic center within the FPGA is determined throughout the entire scanning band. When the center of the second harmonic is located to the right of the entire scanning band, the offset of the DDS signal is decreased in steps of 1mV; when the center of the second harmonic is located to the left of the entire scanning band, the offset of the DDS signal is increased in steps of 1mV. Repeat operation b until the center of the second harmonic is at the midpoint of the entire scanning range. This embodiment can achieve stable scanning of the scanning range of 780.8~760.9nm and resist the influence of environmental changes.

[0042] The glass vials to be tested were placed in the placement room, and the clamps were adjusted to measure the headspace oxygen content of the 22mm diameter 10mL vials.

[0043] Based on an adaptive measurement algorithm for headspace oxygen content of medicine bottles with different packaging specifications, the obtained second harmonic peak value is compensated, that is: Finally, the concentration was fitted using the compensated harmonic peak values ​​to achieve adaptive measurement of headspace oxygen content in medicine bottles of different specifications.

[0044] The photoelectric detection module uses an FDS100 silicon photodiode as the photosensitive element to complete the photoelectric conversion, realizing the detection of lasers with a bandwidth of 10MHz and a wavelength range of 300~1100nm. The adjustable gain range is 0dB~70dB, and a gain of 10dB is selected in this example. The high-precision signal acquisition and generation module includes two functions: spectral signal acquisition and laser current drive signal generation. The signal acquisition unit is connected to a photodetector, acquiring the analog signal after photoelectric conversion and converting it into a digital signal for transmission to the FPGA for further processing. It uses a dual-channel 14-bit AD9248 chip, with a second-order low-pass filter (50kHz cutoff frequency) and a high-pass filter (10kHz cutoff frequency) at the AD front end to remove the DC component and high-frequency noise of the spectral signal. Differential analog signal input ensures signal acquisition quality, achieving a sampling accuracy of ±0.1mV and a maximum sampling bandwidth of 65MSPS. The signal generation module converts the digital modulation signal generated by the FPGA into an analog modulation signal via a DA converter, injecting it into the laser controller as the laser drive signal. The DA conversion module uses a dual-channel, 14-bit DA chip, DA5556, with a second-order low-pass filter (50kHz cutoff frequency) at the DA chip front end to remove high-frequency noise. Differential analog signal input improves the DA conversion accuracy, ultimately achieving a signal generation accuracy of 1mV.

[0045] The FPGA parallel processing module uses Xilinx's ZYNQ7020, and its internal logic development is divided into a DDS generation module, a phase-locked demodulation module, a combined filtering module, a light intensity correction module, and a harmonic feature extraction module.

[0046] (1) The DDS generation module generates a superimposed periodic digital signal of low-frequency ramp and high-frequency sine with adjustable frequency and amplitude. This digital signal is directly connected to the input of the signal generation module and converted by DA to serve as the laser current control signal. (2) The phase-locked demodulation module completes the phase-locked amplification function for the spectral signal. Specifically, the digital spectral signal acquired by AD9248 is used as the input of this module and is multiplied in parallel with the second harmonic sine / cosine reference signal to obtain the X and Y signals. After being processed by the fourth-order cascaded integral comb low-pass filter and the sum of squares, the second harmonic signal is obtained. This signal serves as the basis for oxygen concentration inversion. (3) The combined filtering module performs secondary filtering on the above-mentioned second harmonic signal. Its basic composition is a 39th order FIR filter connected in series with a rectangular window sliding filter. The purpose is to eliminate the glitches of the second harmonic and improve the quality of the harmonic signal. Specifically, the filtering module proposes an adaptive filtering algorithm, the specific implementation of which is as follows: a. Calculate the peak value of the second harmonic sidelobe and take the average of the two peak values:

[0047] b. Calculate the normalized variance of the average peak value of the 93 side lobes;

[0048] in, e To normalize the variance, The sample mean. This represents the sample standard deviation.

[0049] c. The frequency within the FPGA is scanned from 10kHz to 20kHz in 100Hz steps until the normalized variance of the sidelobe peaks is minimized, thus obtaining the optimal modulation frequency of the current laser. f m It is 14.7kHz.

[0050] d. According to the corrected formula R =1.28 f m / 100 represents the number of delays in the differential element of the FPGA's built-in CIC filter. R Adjusted to 188. This completes the adaptive filtering algorithm for the second harmonic, improving its long-term stability.

[0051] (4) The light intensity correction module is implemented based on TDLAS-S 2f / S 0f The calibration-free algorithm based on technical principles aims to eliminate the influence of light intensity on the detection results. Specifically, the peak-to-peak value of the signal after the digital signal acquired by AD9248 is directly passed through a fourth-order CIC low-pass filter is taken as the light intensity characterization value. The influence of light intensity can be eliminated by dividing the second harmonic signal after combined filtering by this light intensity characterization value. (5) The harmonic feature extraction module is used to extract oxygen concentration information based on the characteristics of the second harmonic signal. Specifically, based on the period of the laser control current and the AD sampling rate, the peak value of the second harmonic in each period is obtained as a representation of the oxygen concentration information. (6) The data transmission module is the foundation of human-machine interaction. It allows ZYNQ7020 to transmit harmonic data, harmonic peak-to-peak values, etc. from the PL end to the PS end and then to the host computer via UART. It also allows the host computer to transmit the control quantities of the human-machine interface to the PS end and then to the PL end via UART to complete the adjustment of the FPGA internal parameters. The human-computer interaction module consists of two parts: one part is the measurement interface, which measures the headspace oxygen content of the current object through the measurement button on the screen; the other part is the debugging interface, which requires connecting a PC to the serial port of the instrument and opening the supporting software. The software can perform functions such as configuring laser control parameters, displaying second harmonic waveforms, saving historical data, and displaying FPGA parameters.

[0052] The system power supply module uses lithium batteries to provide ±5V and ±12V power supply voltages to each unit. A voltage monitoring module is also added to promptly issue alarms when the battery power is low.

[0053] The portable laser headspace oxygen analyzer described in this embodiment integrates a light source module, a laser control module, a photoelectric detection module, a high-precision signal acquisition and generation module, an FPGA parallel processing module, and a power supply module. Specifically, the light source module is connected to the laser control module, the photoelectric detection module is connected to the high-precision signal acquisition module, the signal generation module is connected to the EXT LD SET terminal of the laser control module, the high-precision signal acquisition and generation module is connected to the FPGA parallel processing module, and the power supply module is connected to all modules.

[0054] The portable laser headspace oxygen analyzer provided by this invention is characterized by the following mechanical structure: on the one hand, by reducing the optical path of the laser through the outside air, thereby increasing the effective optical path ratio inside the bottle, the proportion of effective spectral signal is enhanced; on the other hand, by minimizing the gap between modules, the instrument volume is only 185. 145 82mm 3 This improves the portability of the instrument of the present invention.

[0055] Specific implementation method of the portable laser headspace oxygen analyzer provided by the present invention: a After inserting two 3.8V lithium batteries, turn on the main power switch; b Turn on the laser temperature control switch (green light 1 is on and red light 2 is off during normal operation); c Turn on the laser current control switch (green light 3 is on and red light 4 is off during normal operation); d Place the glass medicine bottle to be tested into the groove with a diameter of 23mm; e Enter the on-screen measurement interface and click the measurement button on the screen to complete the headspace oxygen content detection in the glass medicine bottle to be tested; f When drastic changes in the detection environment cause laser parameters to drift, the instrument can be connected to a PC to adjust the laser parameters in the host computer software.

[0056] Example 2 This embodiment provides a portable laser headspace oxygen analyzer for 2mL vials 3. The difference from Embodiment 1 is that, based on Embodiment 1, a clamp 2 is placed in a groove to fix the 16mm diameter 2mL vial 3. According to the angle self-adjustment algorithm, the optimal incident angle is 8.5°, and the second harmonic peak compensation formula is: Ultimately, it is possible to achieve accurate measurement of headspace oxygen content in 2mL vials. Figure 4 This is a schematic diagram of the clamp usage.

[0057] Example 3 This embodiment provides a portable laser-based headspace oxygen analyzer. The difference from Embodiment 1 is that the light source module is a high-power laser 1 packaged in DFB packaging. Optionally, oxygen lasers with a wavelength of 760.88nm, such as Nanoplus, Eblana, or Eagleyard, can be used. A schematic diagram of laser replacement is shown below. Figure 5 .

[0058] In this embodiment, considering the laser power, the DFB-packaged high-power laser 1 has an optical power that is approximately 3.3 / 10.7 / 26.7 times (Nanoplus / Eblana / Eagleyard) higher than that of the VCSEL laser in Embodiment 1. This is more conducive to the accurate acquisition of absorption spectrum signals, and the integrated algorithms are adapted to lasers of various power levels.

[0059] Example 4 This embodiment provides a laser-based online headspace oxygen analyzer 4. The difference from Embodiment 1 is that this embodiment provides an external control interface 5, an external acquisition interface 6, and an external communication interface 7. The external control interface 5 is connected to the controller of the laser on the production line to achieve stable control of the laser wavelength; the external acquisition interface 6 is connected to the photodetector on the production line to achieve rapid and accurate acquisition of spectral signals; the external communication interface 7 is connected to the industrial control computer 8 on the production line to complete data communication and PLC control for analyzing the headspace oxygen content of the packaged medicine bottles, realizing online measurement of the headspace oxygen content of the packaged medicine bottles, ultimately forming an online headspace oxygen analyzer for packaged medicine bottles. (See schematic diagram below.) Figure 6 .

[0060] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A portable laser-based headspace oxygen analyzer, comprising a light source module consisting of a narrowband tunable semiconductor laser and a laser housing structure, a laser control module, a sealed glass vial placement chamber, a photoelectric detection module, a high-precision signal acquisition and generation module, an FPGA parallel processing module, a human-machine interaction module, and a power supply module; characterized in that: The laser control module includes temperature control and current control, and the ports for temperature control and current control are directly connected to the laser terminals. The encapsulated glass medicine bottle placement chamber holds the encapsulated glass medicine bottle to be tested. The photoelectric detection module includes a photosensitive element and a photoelectric amplification circuit to complete the photoelectric signal conversion. The output terminal of the photoelectric detection module is connected to the signal acquisition input terminal. The high-precision signal acquisition and generation module includes a photoelectric signal acquisition module and a laser control signal generation module. The output end of the photoelectric signal acquisition module and the input end of the laser control signal generation module are connected to the FPGA, and the output end of the laser control signal generation module is connected to the input end of the laser control module. The FPGA parallel processing module is configured to perform spectral signal processing and oxygen concentration information inversion and transmit it to the human-computer interaction module. The human-computer interaction module includes a measurement interface and a debugging interface; The power supply module is powered by a lithium battery and has a voltage monitoring and alarm function. The light source module allows the laser incident angle to be freely adjusted. The light source module is equipped with an angle adjustment algorithm for self-adjustment of the laser incident angle. The self-adjustment algorithm for the laser incident angle includes: (1) When the laser is incident horizontally, the detection system is continuously measured to obtain the second harmonic signal for M modulation cycles; the second harmonic signal obtained by FPGA demodulation in the kth modulation cycle is denoted as The maximum value of the second harmonic signal is determined as the k-th envelope value of the second harmonic peak envelope sequence. : Sine fitting is performed on the second harmonic peak envelope sequence corresponding to M modulation periods: in, M is the number of modulation periods obtained from continuous measurements, and T is the period of the laser modulation signal. denoted as the offset of the sinusoidal fitting function, and 'a' as the magnitude of the sinusoidal fitting term. The angular frequency of the sinusoidal fitting term is α, and the amplitude α is used to characterize the degree of beam interference at the current laser incident angle. (2) Change the laser incident angle, and re-measure the detection system under the changed laser incident angle to obtain the second harmonic signal of M modulation cycles, obtain the corresponding second harmonic peak envelope sequence and perform sine fitting to obtain the amplitude a corresponding to the changed laser incident angle. (3) Repeat step (2) and determine the laser incident angle corresponding to the minimum amplitude a as the optimal incident angle.

2. The portable laser headspace oxygen analyzer according to claim 1, characterized in that: The light source module is compatible with both DFB-packaged and VCSEL-packaged lasers.

3. The portable laser headspace oxygen analyzer according to claim 1, characterized in that: The encapsulated glass medicine bottle placement chamber is equipped with adjustable clamps for holding glass medicine bottles of different sizes.

4. The portable laser headspace oxygen analyzer according to claim 1, characterized in that: The FPGA parallel processing module includes a lock-in amplification module and a concentration inversion module for absorption spectral signals.

5. The portable laser headspace oxygen analyzer according to claim 4, characterized in that: The FPGA parallel processing module is equipped with a light intensity correction module based on the second harmonic divided by the DC term amplitude.

6. The portable laser headspace oxygen analyzer according to any one of claims 1-5, characterized in that: This includes a self-adjusting algorithm for the laser incident angle in the light source module, a self-correcting algorithm for the wavelength range in the laser control module, an adaptive measurement algorithm for the headspace oxygen content of medicine bottles of different specifications, and an adaptive filtering algorithm in the FPGA parallel processing module.

7. The portable laser headspace oxygen analyzer according to claim 6, characterized in that: The wavelength range self-correction algorithm is as follows: (1) Integrate the second harmonic peak finding algorithm in the FPGA to locate the position of the second harmonic center in the entire scanning band; (2) When the center of the second harmonic is located to the right of the entire scanning band, reduce the offset of the DDS signal generated by the FPGA; when the center of the second harmonic is located to the left of the entire scanning band, increase the offset of the DDS signal generated by the FPGA. (3) Repeat operation (2) until the second harmonic center is at the midpoint of the entire scanning range, and finally achieve the adaptive wavelength scanning range.

8. The portable laser headspace oxygen analyzer according to claim 6, characterized in that, Adaptive measurement algorithms for headspace oxygen content of medicine vials of different specifications include: Based on the inner diameter d of the glass vial to be tested, the peak value of the second harmonic before compensation is calculated. Compensation is performed to obtain the compensated second harmonic peak value. The compensated second harmonic peak value satisfy: in, The modulation coefficient, The concentration of the gas to be measured. For optical path, The current air pressure. For absorption strength, For the incident light intensity, For the full width at half maximum (FWHM) of the Lorentz absorption line, The line shape function of the absorption spectral line. The peak value of the second harmonic before compensation. The peak value of the second harmonic is the compensated value, and d is the inner diameter of the glass medicine bottle to be tested. Based on the compensated second harmonic peak value The headspace oxygen content was fitted to the corresponding headspace oxygen content to obtain headspace oxygen content fitting curves applicable to glass medicine bottles of different specifications.

9. The portable laser headspace oxygen analyzer according to claim 6, characterized in that, The adaptive filtering algorithm includes: (1) For the second harmonic signal demodulated by the FPGA in the kth modulation period, the left sidelobe signal sequence located to the left of the main peak of the second harmonic is obtained respectively. and the right sidelobe signal sequence located to the right of the second harmonic main peak And the peak value of the left side lobe was calculated separately. and right side lobe peak : (2) The left sidelobe peak value of the kth modulation period and right side lobe peak Taking the average, we obtain the average peak value of the sidelobes in the k-th modulation period. : in, M represents the number of modulation cycles participating in the statistics. M is determined based on the laser scanning frequency f and satisfies the following conditions: f is the laser scanning frequency; (3) Calculate the normalized variance e based on the average peak value of the sidelobes corresponding to the M modulation cycles; (4) The frequency within the FPGA is scanned from 10kHz to 20kHz in 100Hz steps until the normalized variance of the average peak value of the sidelobe is minimized. The corresponding modulation frequency at this point is the optimal modulation frequency of the current laser. ; (5) Based on the optimal modulation frequency Correct the number of differential element delays R in the FPGA's built-in CIC filter, where: 。

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