Design And Optimization For The System Of Passive Remote Sensing Mine Gas

In recent years,the explosion of mine gas occurred frequently,which do harm to miners’security and state property.Mine gas is mainly consisting of methane from coal-bed.The available gas detector is given priority to the active remote sensing which require people to detect in short distance that may cause secondary damage of life.Moreover,mine gas detecting system is mainly based detect contact,not flexible-equipped,not fully reflect the density of all locations within the range of gases,unable to detect leaks and cracks face leaks promptly.Firstly,this text put forward utilization imaging interferometer principle,Based on the principles and methods of molecular vibrational and rotational spectra of passive remote sensing mine methane gas concentration and temperature.Detecting the temperature of mine gas primary applicated the principle of molecular“Rotational spectra line temperature measurement method”.According to the turn temperature of molecular dynamic equilibrium to measure the actual temperature,the relationship among the vibrational and rotational spectra,temperature and concentration of mine gas is theoretically put out.The most common four molecular lines of mine gas are listed,respectively,O₂,CO,CH₄ and C₂H₂.Through analysis of the four mine gas lines,selected O₂ and CO as the target detection source finally.Selecting five temperature near 500K of O₂ and CO（500K,510K,520K,530K,540K）,using IDL programming,Obtain the intensity distribution of different spectral intensity which are through the filter,it’s indicate that spectral intensity can be distinguished in 10K intervals when after through the filter,that we designed the instrument for temperature detection accuracy is 10K.According to our selected filer parameters and angle,we obtained the filter transmittance profile from different angles.It validates our selected target lines of the light source and filter is entirely feasibility,moreover establish the theoretical model that imaging detection system measure temperature and concentration.Secondly,simulated the system structure of optical imaging detection,on the basis of calculating the parameters of each device imaging detection instrument.With ZEMAX software simulation platform,using simulation methods for optical imaging detection system to achieve an optical trace,designed the eligible of optimal imaging detection system.Given the optics parameter data tables,3D perspective view,Spot Diagram,Ray Fan,and MTF chart.The results show that:meridional direction at the Nyquist frequency MTF=0.76,full field sagittal direction MTF=0.69,the center of the field view MTF=0.75.Simulation results show that the optical path of the imaging detection system have a good effect.Finally,this paper also specifically for the device involved in the imaging detection system has carried on the theoretical calculation of the MTF.According to calculated the MTF of each part imaging detection system,obtain the entire imaging detection system modulation transfer function expression.The value of modulation transfer function is obtained of 0.8319 at the Nyquist frequency.The MTF values of theoretical calculation and system optimization of the MTF values are basically identical,to ensure the quality of optical imaging system.