Research On Hadamard Single Pixel Camera For Monitoring Gas Leak Distribution

With the rapid development of industrialization,the infrastructure in the field of industrialization is also constantly improving.In industrial production,there are often some invisible gases,these gases may affect the normal operation of equipment.Some invisible toxic gases,and even harm the personal safety of workers.Therefore,monitoring of gases,especially invisible gases,is required.At present,the point detection method,which can effectively classify the gas in the meanwhile has the advantages of fast speed,high accuracy,low cost and easy to operate,is mostly used in the invisible gas monitoring in industry.However,the disadvantages of this method are that it can only detect the presence of gas,and it is unable to image the gas diffusion distribution.In the pipeline leakage scene,it is unable to timely and accurately locate the leakage point,and it is easy to be affected by external factors.Surface imaging can solve the above problems well,but the high price and high technology level limit the application of surface imaging equipment.Therefore,it is necessary to find a low cost invisible gas imaging technology to ensure the safety of workers and the normal operation of production equipment.Aiming at the above problems,this study designed a Hadamard infrared single pixel imaging based on wavelength tuning to monitor gas leakage.Based on the principle of single pixel imaging,combined with infrared wavelength absorption technology,the surface imaging of invisible gas is realized.Wavelength tuning technology is used to enhance the ability of resisting additive noise in the imaging process.An oblique Z sampling method is proposed,which can significantly improve the imaging speed under the premise of satisfying the imaging quality.This paper will study from the following aspects:(1)The principle of single pixel imaging is analyzed theoretically,and the advantages and disadvantages of several commonly used single pixel imaging methods as well as the possibility of subsequent optimization are compared,finally the Hadamard single pixel imaging is selected for gas imaging.The Hadamard single pixel gas imaging simulation for monitoring gas leakage was completed to verify the feasibility of the experiment.(2)Complete the construction of visible light single pixel imaging system,reduce the impact of noise on imaging and improve the signal-to-noise ratio of the system through the difference algorithm.An oblique Z sampling path method is proposed for the first time,which can effectively improve the sampling speed under the premise of satisfying the imaging fidelity.(3)Software based on Labview is developed to control the imaging system.The software has the functions of data display,signal acquisition and parameter setting,and the graphical interactive interface is designed and constructed.The software runs smoothly and can work stably for a long time.(4)The low-cost infrared projection control module is designed to further reduce the system cost.An infrared single-pixel gas imaging system was built based on Labview,and the methane gas with a concentration of 25% was imaging.(5)Two kinds of infrared single pixel gas imaging methods based on real-time modulation of wavelength and single wavelength modulation were proposed respectively,and three kinds of methane gas with different concentrations of 6.25%,12.5% and 25% were achieved respectively for imaging.The experimental results show that both of the two methods enhance the anti-noise ability of the system,reduce the imaging time and improve the accuracy of gas detection.The study shows that the proposed infrared single pixel gas imaging system based on wavelength modulation can recognize methane gas and image it in a planar way.At the same time,the system can qualitatively determine the concentration of methane gas,monitoring the minimum concentration close to the critical explosion point of methane gas.In addition,compared with the existing planar imaging system,the construction cost of this system is significantly reduced.In addition,by adjusting the center wavelength of the laser output to the absorption band of the corresponding gas.The system has a wide range of applications,such as monitoring of a variety of gases.This study provides a new gas imaging method,which can realize the effective surface imaging of a variety of invisible gases,and this method has the advantages of low cost and strong anti-noise ability,so it has important application value in industrial production.