A high-sensitivity optical system based on optical waveguide

Abstract

The application discloses a kind of high sensitivity optical systems based on optical waveguide, it is related to environmental monitoring field, including: light source module, for emitting middle infrared waveband preset wavelength laser;Coupling air chamber module, for the laser of light source module operation emission is coupled into calcium fluoride-based optical waveguide;Gas sensing modulation module, for after containing pollutant atmosphere sample is sent into air chamber by micro flow pump at constant speed by gas inlet, sense light signal carrying pollutant information;Optical signal processing module, for amplifying and screening processing to light signal carrying pollutant information;Detection module, for obtaining the light signal of optical signal processing module operation processing, light signal is quickly and accurately converted into digital electrical signal;The application can efficiently sense pollutant information by accurately corresponding pollutant characteristic absorption peak, cooperate micro flow pump and gas sensing modulation module, provide intuitive, accurate data support for environmental protection workers, help precise management air pollution, protect ecological environment.

Description

Technical Field

[0001] This invention relates to the field of environmental monitoring technology, specifically to a high-sensitivity optical system based on optical waveguides. Background Technology

[0002] Trace pollutants refer to a class of pollutants that exist in the environment at extremely low concentrations, usually measured in micrograms per liter or nanograms per liter. Although their content is extremely small, they may be highly toxic, bioaccumulative, and persistent, posing potential hazards to the ecological environment and human health.

[0003] The invention patent application with application number 201610612116.X discloses an indoor air quality monitoring method, which determines the pollutant concentration map within the monitoring location, including the following steps: (1) moving the monitoring system along the monitoring location for scanning; the monitoring system includes: a sensor, which can monitor the pollutant concentration at a specific sensing point; an analysis system, which is used to analyze the detection results of the sensor; and a display system, which displays the pollutant concentration at the monitoring location based on the results of the analysis system; the sensor includes a first sensor and a second sensor, the first sensor is set at the air inlet of the air purification device to detect the air pollutant concentration before purification, and the second sensor is set at the air outlet of the air purification device to detect the air pollutant concentration after purification; (2) determining that the sensing point is in a purification equilibrium state based on the detection results of the first sensor and the second sensor at the sensing point along the moving scanning path. This application aims to solve the problem that "the prior art cannot monitor the entire indoor air quality, or the monitoring results are not real-time".

[0004] However, there are currently few reliable detection technologies for trace pollutants in the atmosphere.

[0005] To address this, a high-sensitivity optical system based on optical waveguides is proposed. Summary of the Invention

[0006] In view of the above-mentioned shortcomings of the prior art, the present invention provides a high-sensitivity optical system based on optical waveguide, which can effectively solve the problems of the prior art.

[0007] To achieve the above objectives, the present invention provides the following technical solution:

[0008] This invention discloses a high-sensitivity optical system based on optical waveguides, comprising:

[0009] The system comprises the following modules: a light source module for emitting laser light of a preset wavelength in the mid-infrared band; a coupling gas chamber module for coupling the laser light emitted by the light source module into a calcium fluoride-based optical waveguide; a gas sensing modulation module for sensing the optical signal carrying pollutant information after a pollutant-containing atmospheric sample is uniformly fed into the gas chamber via a microfluidic pump; an optical signal processing module for amplifying and filtering the optical signal carrying pollutant information; a detection module for acquiring the optical signal processed by the optical signal processing module and quickly and accurately converting it into a digital electrical signal; a signal analysis module for receiving and analyzing the digital electrical signal obtained by the detection module; and an output module for acquiring and outputting the analyzed digital electrical signal from the signal analysis module.

[0010] The detection module uses a mercury cadmium telluride detector that operates based on the internal photoelectric effect to convert digital electrical signals.

[0011] Furthermore, the number and wavelength of the mid-infrared band emitted by the light source module are customized by the system user. The mid-infrared band emitted by the light source module precisely corresponds to the characteristic absorption peaks of sulfur dioxide, nitrogen oxides, and volatile organic compounds. The light source module is integrated by an integrated multi-wavelength quantum cascade laser.

[0012] Furthermore, the light source module is equipped with a maintenance unit and a control unit. The maintenance unit is used to monitor the operating temperature of the light source module and adjust the temperature fluctuation of the light source module during operation to be within ±0.1 degrees Celsius. The control unit is used to control the driving current of the light source module to keep the laser power fluctuation of each wavelength within ±0.003dBm / h.

[0013] The maintenance unit integrates a thermistor and a thermoelectric cooler. The control unit contains a current drive circuit composed of a 16-bit resolution digital-to-analog converter and an operational amplifier to control the drive current of the light source module.

[0014] Furthermore, during the operation of the coupling chamber module, the optical waveguide and the gas flow chamber are integrated simultaneously.

[0015] In the optical waveguide coupling stage, a wedge-shaped coupling structure is adopted, and the error is constrained to ±0.01° by controlling the wedge angle, and the coupling position is controlled with an accuracy error of less than ±0.1μm and a coupling efficiency of not less than 88%.

[0016] The gas flow chamber is equipped with a light-reflecting structure, and the reflectivity of the light-reflecting structure is not less than 99%.

[0017] Furthermore, the flow rate accuracy of the microfluidic pump is controlled within the range of ±0.1 mL / min. During the operation of the gas sensing modulation module, based on the molecular structure and vibration mode of the pollutant molecules, the module causes them to absorb laser energy of the corresponding wavelength to sense the light signal carrying pollutant information.

[0018] The gas sensing modulation module is integrated with an electro-optic modulator. The electro-optic modulator is based on the Pockels effect. An electrical signal with a frequency of 10kHz-100kHz and an amplitude of 0-10V is applied to its two ends to achieve frequency modulation of the optical signal. A reference signal with the same modulation frequency is generated by a signal generator. The detection signal and the reference signal are multiplied by a multiplier based on lock-in amplification. The high-frequency components are filtered out by a low-pass filter, and only the low-frequency signal with the same frequency as the reference signal is retained.

[0019] Furthermore, during the operation of the optical signal processing module, the mid-infrared band erbium-doped fiber amplifier is based on the population inversion phenomenon generated by erbium ions under the action of 980nm or 1480nm optical pumping.

[0020] The optical signal amplification processing logic in the optical signal processing module is represented as follows:

[0021] Set amplifier gain:

[0022] ;

[0023] Calculate the output power:

[0024] ;

[0025] In the formula: Input power;

[0026] The amplifier gain is initially set to 32dB by default.

[0027] Furthermore, during the operation of the optical signal processing module, when filtering the optical signal, a bandpass filter operates based on the principle of thin-film interference. The filtering logic of the optical signal processing module is expressed as follows:

[0028] ;

[0029] In the formula: is the refractive index of the thin film; The thickness of the film; The angle of refraction of light within the thin film; The interference series number takes values ​​of 1, 2, 3, ...; Wavelength;

[0030] In the optical signal selection process, only those conditions for interference enhancement mentioned above are allowed to be met, namely... And the wavelength is at the preset center wavelength of the filter. and its bandwidth Optical signals within the specified range are retained, while the remaining optical signals are filtered out.

[0031] Furthermore, during the operation phase of the signal analysis module, based on the Fourier transform infrared spectroscopy analysis algorithm and the discrete Fourier transform principle, the processor performs fast Fourier transform operations on the digital electrical signal. By analyzing the position and intensity of the characteristic peaks in the frequency domain signal, the concentration of each pollutant is calculated according to the Lambert-Beer law.

[0032] Furthermore, the calculated concentration results of each pollutant are displayed in real time on a screen. The display interface intuitively presents the type, concentration, and unit of the pollutants. Simultaneously, the calculation results are uploaded to the environmental monitoring center via a wireless network. The environmental monitoring center, based on a geographic information system, converts the data into a pollution map to represent the spatial distribution of pollutants.

[0033] Furthermore, the lower level of the light source module is interconnected with a maintenance unit and a control unit via a wireless network. The light source module is interconnected with a coupling gas chamber module, a gas sensing modulation module, and an optical signal processing module via a wireless network. The optical signal processing module is interconnected with a detection module and a signal analysis module via a wireless network. The signal analysis module is interconnected with the output module via a wireless network.

[0034] Compared with the known prior art, the technical solution provided by this invention has the following beneficial effects:

[0035] In this invention, the system can precisely emit mid-infrared laser light that matches the absorption peak of pollutants by controlling the light source, ensuring high stability of wavelength and power. In the integrated design of the optical waveguide and gas flow chamber, a special coupling structure is used to achieve efficient laser coupling. The unique reflection structure in the gas flow chamber greatly increases the interaction length between light and gas, effectively improving detection sensitivity. In the gas sensing stage, innovative light modulation and noise suppression technologies enable accurate detection in high-noise environments. During optical signal processing, specially designed amplifiers and filters can effectively amplify and filter signals. High-sensitivity detection and high-speed data acquisition work together to quickly convert optical signals. The analysis module uses advanced algorithms to calculate pollutant concentrations and combines GIS technology to present results intuitively and predict trends, comprehensively improving detection performance. Attached Figure Description

[0036] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the accompanying drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are merely some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without any creative effort.

[0037] Figure 1 This is a schematic diagram of a high-sensitivity optical system based on an optical waveguide. Detailed Implementation

[0038] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. 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.

[0039] The present invention will be further described below with reference to embodiments.

[0040] Example:

[0041] This embodiment provides a high-sensitivity optical system based on optical waveguides, such as... Figure 1 As shown, it includes:

[0042] The light source module is used to emit laser light of a preset wavelength in the mid-infrared band;

[0043] The number and wavelength of the mid-infrared band emitted by the light source module are defined by the system user. The mid-infrared band emitted by the light source module must precisely correspond to the characteristic absorption peaks of sulfur dioxide, nitrogen oxides, and volatile organic compounds. The light source module is integrated by an integrated multi-wavelength quantum cascade laser.

[0044] The light source module is equipped with a maintenance unit and a control unit. The maintenance unit is used to monitor the operating temperature of the light source module and adjust the temperature fluctuation of the light source module during operation to be within ±0.1 degrees Celsius. The control unit is used to control the driving current of the light source module to keep the laser power fluctuation of each wavelength within ±0.003dBm / h.

[0045] The maintenance unit is integrated with a thermistor and a thermoelectric cooler. The control unit has a current drive circuit composed of a 16-bit resolution digital-to-analog converter and an operational amplifier to control the drive current of the light source module.

[0046] The coupling chamber module is used to couple the laser emitted by the light source module into the calcium fluoride-based optical waveguide;

[0047] The light source module is equipped with a maintenance unit and a control unit. The maintenance unit is used to monitor the operating temperature of the light source module and adjust the temperature fluctuation of the light source module during operation to be within ±0.1 degrees Celsius. The control unit is used to control the driving current of the light source module to keep the laser power fluctuation of each wavelength within ±0.003dBm / h.

[0048] The maintenance unit is integrated with a thermistor and a thermoelectric cooler. The control unit has a current drive circuit composed of a 16-bit resolution digital-to-analog converter and an operational amplifier to control the drive current of the light source module.

[0049] The gas sensing modulation module is used to sense the light signal carrying pollutant information after an atmospheric sample containing pollutants is uniformly fed into the gas chamber through the inlet by a microfluidic pump.

[0050] The flow rate of the microfluidic pump is controlled within ±0.1 mL / min. During the operation of the gas sensing modulation module, based on the molecular structure and vibration mode of the pollutant molecules, the pump absorbs laser energy of the corresponding wavelength to sense the light signal carrying the pollutant information.

[0051] The gas sensing modulation module is integrated with an electro-optic modulator. The electro-optic modulator is based on the Pockels effect. An electrical signal with a frequency of 10kHz-100kHz and an amplitude of 0-10V is applied to its two ends to achieve frequency modulation of the optical signal. A reference signal with the same modulation frequency is generated by a signal generator. The detection signal and the reference signal are multiplied by a multiplier based on lock-in amplification. The high-frequency components are filtered out by a low-pass filter, and only the low-frequency signal with the same frequency as the reference signal is retained.

[0052] The optical signal processing module is used to amplify and filter optical signals carrying pollutant information;

[0053] During the operation of the optical signal processing module, the mid-infrared band erbium-doped fiber amplifier is based on the population inversion phenomenon generated by erbium ions under the action of 980nm or 1480nm optical pumping.

[0054] The logic for amplifying optical signals in the optical signal processing module is represented as follows:

[0055] Set amplifier gain:

[0056] ;

[0057] Calculate the output power:

[0058] ;

[0059] In the formula: Input power;

[0060] The amplifier gain is initially set to 32dB by default.

[0061] During the operation of the optical signal processing module, when filtering the optical signal, a bandpass filter operates based on the principle of thin-film interference. The filtering logic of the optical signal processing module is represented as follows:

[0062] ;

[0063] In the formula: is the refractive index of the thin film; The thickness of the film; The angle of refraction of light within the thin film; The interference series number takes values ​​of 1, 2, 3, ...; Wavelength;

[0064] In the optical signal selection process, only those conditions for interference enhancement mentioned above are allowed to be met, namely... And the wavelength is at the preset center wavelength of the filter. and its bandwidth Light signals within the specified range are retained, while the remaining light signals are filtered out.

[0065] The above logical formula is used to calculate and filter optical signals, effectively improving the accuracy of the optical signals and providing more accurate and reliable data support for the further operation of the system in this embodiment.

[0066] The detection module is used to acquire the optical signal processed by the optical signal processing module and convert the optical signal into a digital electrical signal quickly and accurately.

[0067] The signal analysis module is used to receive the digital electrical signals obtained by the detection module and analyze the digital electrical signals.

[0068] During the signal analysis module operation phase, based on the Fourier transform infrared spectroscopy analysis algorithm and the discrete Fourier transform principle, the processor performs fast Fourier transform operations on the digital electrical signal. By analyzing the position and intensity of the characteristic peaks in the frequency domain signal, the concentration of each pollutant is calculated according to the Lambert-Beer law.

[0069] The calculated concentration results of each pollutant are displayed in real time on the screen. The display interface intuitively presents the type, concentration and unit of the pollutant. Simultaneously, the calculation results are uploaded to the environmental monitoring center via wireless network. The environmental monitoring center uses a geographic information system to convert the data into a pollution map to represent the spatial distribution of pollutants.

[0070] The output module is used to acquire the digital electrical signals that have been analyzed in the signal analysis module and output the analyzed digital electrical signals.

[0071] The detection module uses a mercury cadmium telluride detector that operates based on the internal photoelectric effect to complete the conversion of digital electrical signals.

[0072] The light source module is connected to a maintenance unit and a control unit via a wireless network. The light source module is also connected to a coupling gas chamber module, a gas sensing modulation module, and an optical signal processing module via a wireless network. The optical signal processing module is connected to a detection module and a signal analysis module via a wireless network. The signal analysis module is connected to the output module via a wireless network.

[0073] In this embodiment, the light source module emits laser light of a preset wavelength in the mid-infrared band. The maintenance unit synchronously monitors the operating temperature of the light source module and adjusts the temperature fluctuation during operation to within ±0.1 degrees Celsius. The control unit controls the driving current of the light source module in real time to keep the laser power fluctuation of each wavelength within ±0.003 dBm / h. The coupling chamber module operates in the rear to couple the laser light emitted by the light source module into the calcium fluoride-based optical waveguide. The gas sensing modulation module further senses the light signal carrying pollutant information after the air sample containing pollutants is uniformly fed into the gas chamber through the inlet by a microfluidic pump. The light signal processing module then amplifies and filters the light signal carrying pollutant information. The detection module obtains the light signal processed by the light signal processing module and quickly and accurately converts the light signal into a digital electrical signal. The signal analysis module operates in conjunction to receive the digital electrical signal obtained by the detection module, analyzes the digital electrical signal, and finally, the output module obtains the digital electrical signal that has been analyzed in the signal analysis module and outputs the analyzed digital electrical signal.

[0074] The system described in the above embodiments can emit mid-infrared lasers in a custom manner to accurately correspond to the characteristic absorption peaks of pollutants. Combined with a microfluidic pump and a gas sensing modulation module, it can efficiently sense pollutant information. After optical signal processing, detection, and analysis, the concentration of pollutants can be quickly and accurately determined. Finally, the calculation results can not only be displayed on the screen in real time, but also uploaded to the environmental monitoring center to generate a pollution map, providing intuitive and accurate data support for environmental protection workers, helping to accurately control air pollution and protect the ecological environment.

[0075] In summary, the system in the above embodiments, through careful control of the light source, can accurately emit mid-infrared laser light that matches the absorption peaks of pollutants, ensuring high stability of wavelength and power. In the integrated design of the optical waveguide and gas flow chamber, a special coupling structure is used to achieve efficient laser coupling. The unique reflection structure in the gas flow chamber greatly increases the interaction length between light and gas, effectively improving detection sensitivity. In the gas sensing stage, innovative light modulation and noise suppression technologies enable accurate detection in high-noise environments. During optical signal processing, specially designed amplifiers and filters can effectively amplify and filter signals. High-sensitivity detection and high-speed data acquisition work together to quickly convert optical signals. Finally, advanced algorithms are used to calculate pollutant concentration, and combined with GIS technology, the results are presented intuitively and trends are predicted, comprehensively improving detection performance.

[0076] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions will not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A high-sensitivity optical system based on optical waveguides, characterized in that, include: The light source module is used to emit laser light of a preset wavelength in the mid-infrared band; The coupling chamber module is used to couple the laser emitted by the light source module into the calcium fluoride-based optical waveguide; During the operation of the coupling gas chamber module, the optical waveguide and the gas flow chamber are integrated simultaneously. In the optical waveguide coupling stage, a wedge-shaped coupling structure is adopted, and the error is constrained to ±0.01° by controlling the wedge angle, and the coupling position is controlled to achieve an accuracy error of less than ±0.1μm and a coupling efficiency of not less than 88%. The gas flow chamber is equipped with a light-reflecting structure, and the reflectivity of the light-reflecting structure is not less than 99%. The gas sensing modulation module is used to sense the light signal carrying pollutant information after an atmospheric sample containing pollutants is uniformly fed into the gas chamber through the inlet by a microfluidic pump. The flow rate of the microfluidic pump is controlled within ±0.1 mL / min. During the operation of the gas sensing modulation module, based on the molecular structure and vibration mode of the pollutant molecules, the module causes them to absorb laser energy of the corresponding wavelength to sense the light signal carrying pollutant information. The gas sensing modulation module is integrated with an electro-optic modulator. The electro-optic modulator is based on the Paul Kers effect. An electrical signal with a frequency of 10kHz-100kHz and an amplitude of 0-10V is applied to its two ends to achieve frequency modulation of the optical signal. A reference signal with the same modulation frequency is generated by a signal generator. The detection signal and the reference signal are multiplied by a multiplier based on a lock-in amplifier. The high-frequency components are filtered out by a low-pass filter, and only the low-frequency signal with the same frequency as the reference signal is retained. The optical signal processing module is used to amplify and filter optical signals carrying pollutant information; The detection module is used to acquire the optical signal processed by the optical signal processing module and convert the optical signal into a digital electrical signal quickly and accurately. The signal analysis module is used to receive the digital electrical signals obtained by the detection module and analyze the digital electrical signals. The output module is used to acquire the digital electrical signals that have been analyzed in the signal analysis module and output the analyzed digital electrical signals. The detection module uses a mercury cadmium telluride detector that operates based on the internal photoelectric effect to convert digital electrical signals.

2. The high-sensitivity optical system based on optical waveguide according to claim 1, characterized in that, The number and wavelength of the mid-infrared band emitted by the light source module are defined by the system user. The mid-infrared band emitted by the light source module corresponds precisely to the characteristic absorption peaks of sulfur dioxide, nitrogen oxides, and volatile organic compounds. The light source module is integrated by an integrated multi-wavelength quantum cascade laser.

3. The high-sensitivity optical system based on optical waveguide according to claim 1, characterized in that, The light source module is equipped with a maintenance unit and a control unit. The maintenance unit is used to monitor the operating temperature of the light source module and adjust the temperature fluctuation of the light source module during operation to be within ±0.1 degrees Celsius. The control unit is used to control the driving current of the light source module to keep the laser power fluctuation of each wavelength within ±0.003dBm / h. The maintenance unit integrates a thermistor and a thermoelectric cooler. The control unit contains a current drive circuit composed of a 16-bit resolution digital-to-analog converter and an operational amplifier to control the drive current of the light source module.

4. A high-sensitivity optical system based on an optical waveguide according to claim 1, characterized in that, During the operation of the optical signal processing module, the mid-infrared band erbium-doped fiber amplifier is based on the population inversion phenomenon generated by erbium ions under the action of 980nm or 1480nm optical pumping. The optical signal amplification processing logic in the optical signal processing module is represented as follows: Set amplifier gain: ； Calculate the output power: ； In the formula: Input power; The amplifier gain is initially set to 32dB by default.

5. A high-sensitivity optical system based on an optical waveguide according to claim 1, characterized in that, During the operation of the optical signal processing module, when filtering the optical signal, a bandpass filter operates based on the principle of thin-film interference. The filtering logic of the optical signal processing module is expressed as follows: ； In the formula: is the refractive index of the thin film; The thickness of the film; The angle of refraction of light within the thin film; The interference series number takes values ​​of 1, 2, 3, ...; Wavelength; In the optical signal filtering process, only signals that meet the following conditions are allowed: And the wavelength is at the preset center wavelength of the filter. and its bandwidth Optical signals within the specified range are retained, while the remaining optical signals are filtered out.

6. A high-sensitivity optical system based on an optical waveguide according to claim 1, characterized in that, During the operation phase of the signal analysis module, based on the Fourier transform infrared spectroscopy analysis algorithm and the discrete Fourier transform principle, the processor performs fast Fourier transform operations on the digital electrical signal. By analyzing the position and intensity of the characteristic peaks in the frequency domain signal, the concentration of each pollutant is calculated according to the Lambert-Beer law.

7. A high-sensitivity optical system based on an optical waveguide according to claim 6, characterized in that, The calculated concentration results of each pollutant are displayed in real time on a screen. The display interface intuitively presents the type, concentration, and unit of the pollutants. Simultaneously, the calculation results are uploaded to the environmental monitoring center via a wireless network. The environmental monitoring center, based on a geographic information system, converts the data into a pollution map to represent the spatial distribution of pollutants.

8. A high-sensitivity optical system based on an optical waveguide according to claim 1, characterized in that, The lower level of the light source module is interconnected with a maintenance unit and a control unit via a wireless network. The light source module is interconnected with a coupling gas chamber module, a gas sensing modulation module and an optical signal processing module via a wireless network. The optical signal processing module is interconnected with a detection module and a signal analysis module via a wireless network. The signal analysis module is interconnected with the output module via a wireless network.

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