CN214374255U - High-precision photoacoustic spectrometer - Google Patents
High-precision photoacoustic spectrometer Download PDFInfo
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- CN214374255U CN214374255U CN202120288868.1U CN202120288868U CN214374255U CN 214374255 U CN214374255 U CN 214374255U CN 202120288868 U CN202120288868 U CN 202120288868U CN 214374255 U CN214374255 U CN 214374255U
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Abstract
The invention discloses a high-precision photoacoustic spectrometer which comprises an infrared radiation light source, a chopper, a filter wheel and a photoacoustic cell, wherein a microphone is arranged in the photoacoustic cell and used for detecting that gas to be detected absorbs infrared light to generate periodic pressure acoustic waves and transmitting the periodic pressure acoustic waves to a control circuit board, and the control circuit board is used for processing pressure acoustic wave signals and calculating a component analysis result; the infrared radiation light source is externally wrapped by a heat conduction shell, the heat conduction shell is provided with a temperature measuring element and a heating module, the temperature measuring element detects the temperature of the heat conduction shell in real time and sends the temperature to a temperature control circuit, the temperature control circuit controls the power of the heating module to heat the heat conduction shell, and when the temperature control circuit detects that a temperature signal is stable, a signal for starting detection is sent to a control circuit board to perform detection and analysis on a component to be detected. The invention can improve the stability of the detection signal of the photoacoustic spectrometer and enable the component test result to be more accurate.
Description
Technical Field
The invention relates to a photoelectric detection device, in particular to a high-precision photoacoustic spectrometer.
Background
Photoacoustic spectroscopy is a new technique for studying the absorption spectrum of substances and has become an important branch of molecular spectroscopy. As a powerful analysis tool for the research in the field of modern biomedicine, the photoacoustic spectroscopy technology overcomes the influence of tissue scattering characteristics on the measurement result, and provides a nondestructive effective detection method which has high sensitivity and can carry out no pretreatment on the sample for the research of a biological tissue sample. Besides, the photoacoustic spectroscopy has extremely high sensitivity to various trace gases, and is widely applied to the fields of petrochemical industry, industrial sites and the like, such as the detection of alkane gases dissolved in extra-high voltage transformer oil, the detection of industrial toxic and harmful gas leakage and the like.
There are many factors that affect the stability of the detection signal of the photoacoustic spectrometer, such as the stability of the power of the excitation light source, the noise interference of the photoacoustic cell, the performance of the microphone, the design of the phase-locked circuit, etc. How to improve the stability of the detection signal of the photoacoustic spectrometer by optimizing the design is provided, a plurality of methods are proposed and widely used, but the influence on the power stability of the excitation light source is less concerned. The excitation light sources of photoacoustic spectrometers are generally classified into two types: an infrared thermal radiation light source and a semiconductor laser. The former has low cost and low signal-to-noise ratio; the latter is costly and has a high signal-to-noise ratio. However, the cost of lasers has increased dramatically due to the need for multi-component measurements, so most systems have integrated infrared thermal radiation sources. In summary, the stability of the signal detected by the photoacoustic spectrometer widely used for multi-component detection is poor, and the stability needs to be solved.
Disclosure of Invention
The purpose of the invention is as follows: aiming at the problems, the invention provides a high-precision photoacoustic spectrometer which can improve the stability of a detection signal of the photoacoustic spectrometer and enable a component test result to be more accurate.
The technical scheme is as follows: the technical scheme adopted by the invention is that the high-precision photoacoustic spectrometer comprises an infrared radiation light source, a chopper, an optical filter wheel and a photoacoustic cell which are sequentially arranged along the light ray emission direction, wherein a microphone is arranged in the photoacoustic cell, the photoacoustic cell is used for detecting periodic pressure acoustic wave signals generated after gas to be detected absorbs infrared rays and transmitting the periodic pressure acoustic wave signals to a control circuit board, the control circuit board comprises a signal processing module for processing the pressure acoustic wave signals, and the control circuit board is also used for controlling the starting and stopping of the infrared radiation light source, the chopper and the optical filter wheel; the infrared radiation light source is externally wrapped by a heat conduction shell, the heat conduction shell is provided with a temperature measuring element and a heating module, the temperature measuring element detects the temperature of the heat conduction shell in real time and sends the temperature to a temperature control circuit, and the temperature control circuit controls the power of the heating module to heat the heat conduction shell.
The temperature control circuit controls the power of the heating module by adopting a PID algorithm to heat the heat conducting shell.
The heat conducting shell is made of high heat conducting metal materials such as aluminum alloy or copper.
The heating module is a thermal resistor, an electromagnetic heating ring or a TEC semiconductor heating plate.
The temperature measuring element is a thermistor or a thermocouple.
Has the advantages that: compared with the prior art, the invention has the following advantages: the power of the heating module can be effectively controlled, so that the infrared radiation light source reaches a stable set temperature, the fluctuation of a detection signal caused by the influence of the thermal stability of the infrared radiation light source is eliminated, and the stability of the detection signal of the photoacoustic spectrometer is improved.
Drawings
FIG. 1 is a schematic diagram of a conventional photoacoustic spectrometer;
FIG. 2 is a schematic diagram of a high-precision photoacoustic spectrometer according to the present invention.
Detailed Description
The technical solution of the present invention is further described below with reference to the accompanying drawings and examples.
As shown in fig. 1, the conventional structure of the photoacoustic spectrometer includes an infrared radiation light source 1, and a chopper 2, a filter wheel 3 and a photoacoustic cell 4 arranged in sequence along the light emission direction, and a control circuit board 6 electrically connected to the infrared radiation light source 1, the chopper 2 and the filter wheel 3 for controlling the start and stop of the above structure. The microphone 5 is arranged in the photoacoustic cell 4, and the photoacoustic cell 4 is used for detecting that the gas to be detected absorbs the infrared light to generate periodic pressure acoustic waves and then sends the periodic pressure acoustic waves to the control circuit board 6. The control circuit board 6 comprises a signal processing module for processing the pressure sound wave signal and calculating a component analysis result. In the research of multi-component detection, we find that the stability of a light source is changed greatly with time along with self-heating and ambient heat exchange besides the factors which are known to influence the stability of the detection signal of the photoacoustic spectrometer, so that an improved photoacoustic spectrometer is provided.
The high-precision photoacoustic spectrometer is formed by improving the conventional photoacoustic spectrometer based on the discovery. As shown in the attached figure 2, the photoacoustic spectrometer device is improved on the basis, the heating module 8 generates heat and transmits the heat to the heat conducting shell 7, the heat is further transmitted to the infrared radiation light source 1 and heated, the temperature measuring element 9 detects the temperature of the heat conducting shell 7 in real time and transmits the temperature to the temperature control circuit 10, and the power of the heating module 8 is effectively controlled through calculation and analysis of a PID algorithm, so that the infrared radiation light source 1 reaches a stable set temperature, the fluctuation of a detection signal caused by the influence of the thermal stability of the infrared radiation light source 1 is eliminated, and the stability of the detection signal of the photoacoustic spectrometer is improved. And when the temperature control circuit detects that the temperature signal is stable, sending a signal for starting detection to the control circuit board for component detection and analysis. The detection analysis method in the scheme adopts the existing photoacoustic spectrum analysis method, and the detection analysis method is not improved. The infrared light emitted by the infrared radiation light source 1 passes through the chopper 2 and then is changed into periodic light, the periodic light passes through the filter wheel 3 and then is selected with specific wavelength, finally the light with specific wavelength and specific period enters the photoacoustic cell 4, the gas to be measured absorbs the infrared light and then generates periodic pressure sound waves, the periodic pressure sound waves are detected by the microphone 5 and transmitted to the control circuit board 6, and effective signals can be obtained after the processing such as filtering and phase-locked amplification, so that the concentration of the gas to be measured in the photoacoustic cell 4 can be calculated.
The working principle of the device is as follows: the heat conduction shell 7 conducts heat to the infrared radiation light source 1, the heating module 8 heats the light source, the temperature measuring element 9 detects temperature in real time and sends the temperature control circuit 10, heating power is adjusted through the existing PID algorithm, finally the infrared radiation light source 1 is kept at a set temperature, detection is carried out after the purpose of stabilizing light source output is achieved, and detection precision is improved. Specifically, firstly, the temperature measuring element 9 detects the temperature of the heat conducting shell 7 in real time and sends the temperature to the temperature control circuit 10, and the temperature control circuit 10 adopts a PID algorithm to control the power of the heating module 8 to heat the heat conducting shell 7; then, when the temperature control circuit 10 detects that the temperature signal is stable, a signal for starting detection is sent to the control circuit board 6; finally, the control circuit board 6 controls the infrared radiation light source 1 to emit infrared light, the infrared light is changed into periodically emitted light after passing through the chopper 2, specific wavelength selection is carried out after passing through the filter wheel 3, finally the light with specific wavelength and specific period enters the photoacoustic cell 4, the gas to be detected absorbs the infrared light to generate periodic pressure sound waves, the periodic pressure sound waves are detected by the microphone 5 and transmitted to the circuit board 6, effective signals can be obtained after the processing such as filtering and phase-locked amplification, and therefore the concentration of the gas to be detected in the photoacoustic cell 4 is calculated.
Claims (5)
1. A high accuracy photoacoustic spectrometer is characterized in that: the device comprises an infrared radiation light source (1), a chopper (2), a filter wheel (3) and a photoacoustic cell (4) which are sequentially arranged along the light ray emission direction, wherein a microphone (5) is arranged in the photoacoustic cell (4), the photoacoustic cell (4) is used for detecting periodic pressure acoustic wave signals generated after gas to be detected absorbs infrared light rays and transmitting the periodic pressure acoustic wave signals to a control circuit board (6), the control circuit board (6) comprises a signal processing module and is used for processing the pressure acoustic wave signals, and the control circuit board (6) is also used for controlling the start and stop of the infrared radiation light source (1), the chopper (2) and the filter wheel (3); the infrared radiation light source (1) is externally wrapped by a heat conduction shell (7), the heat conduction shell (7) is provided with a temperature measuring element (9) and a heating module (8), the temperature measuring element (9) detects the temperature of the heat conduction shell (7) in real time and sends the temperature to a temperature control circuit (10), and the temperature control circuit (10) controls the power of the heating module (8) to heat the heat conduction shell (7).
2. The high precision photoacoustic spectrometer of claim 1, wherein: the temperature control circuit (10) adopts a PID algorithm to control the power of the heating module (8) to heat the heat conducting shell (7).
3. The high precision photoacoustic spectrometer of claim 1, wherein: the heat conduction shell (7) is made of a high-heat-conductivity metal material, and the heat conduction shell (7) is made of aluminum alloy or copper.
4. The high precision photoacoustic spectrometer of claim 1, wherein: the heating module (8) adopts a thermal resistor, an electromagnetic heating ring or a TEC semiconductor heating plate.
5. The high precision photoacoustic spectrometer of claim 1, wherein: the temperature measuring element (9) is a thermistor or a thermocouple.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202120288868.1U CN214374255U (en) | 2021-02-01 | 2021-02-01 | High-precision photoacoustic spectrometer |
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| Application Number | Priority Date | Filing Date | Title |
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| CN202120288868.1U CN214374255U (en) | 2021-02-01 | 2021-02-01 | High-precision photoacoustic spectrometer |
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| CN214374255U true CN214374255U (en) | 2021-10-08 |
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| CN202120288868.1U Active CN214374255U (en) | 2021-02-01 | 2021-02-01 | High-precision photoacoustic spectrometer |
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2021
- 2021-02-01 CN CN202120288868.1U patent/CN214374255U/en active Active
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Effective date of registration: 20230509 Address after: No. 19 Hengfei Road, Nanjing Economic and Technological Development Zone, Nanjing, Jiangsu Province, 210000 Patentee after: NANJING INSTITUTE OF ADVANCED LASER TECHNOLOGY Patentee after: NANJING ZHONGKE SHENGUANG TECHNOLOGY Co.,Ltd. Address before: 211100 building a, Longgang Science Park, Hengyuan Road, Nanjing Economic and Technological Development Zone, Nanjing, Jiangsu Province Patentee before: NANJING ZHONGKE SHENGUANG TECHNOLOGY Co.,Ltd. |