Research On The Measurement System Of Laser-induced Aerosol

The atmospheric aerosol is particulate matter which exists in solid or liquid form suspended in the atmosphere.When the light travels in the atmosphere,it is affected by aerosols,which in turn affects the radiation of sunlight in the atmosphere.It has great significance to the study of aerosol particles.In this dissertation,based on the absorption effect of aerosol filtration membrane,a set of experimental device for measuring the aerosol absorption coefficient is designed.The measuring apparatus adopts a polarization type folded back Jamin interferometer as a basic structure and uses a four-beam polarization interference technique to simplify the system structure.It effectively controls the cost of the experimental device,effectively reduces the impact of external environmental changes on the experimental device,and improves the accuracy and stability of the measurement system.The measurement system uses atmospheric aerosol as an experimental research object.The main research work is as follows.Based on the absorption principle of aerosol filtration membrane,a method for measuring atmospheric aerosol absorption coefficient using photo-thermal interference method is proposed.The Jamin interferometer structure is optimized and a set of measurement system based on polarization-based Jamin interferometer structure is designed.The working principle of the polarization-type Jamin interferometer is introduced.The optical path of the measurement system is designed and analyzed.The optical properties of the aerosol filtration membrane are described.And the reflectance and transmittance of the filtration membrane are analyzed.Then,the influence of the scattering effect of the aerosol filtration membrane is analyzed.The dissertation analyzes the absorption effect of aerosol filtration membrane in vivo and its surface absorption effect and its mathematical expression,which provides a theoretical basis for measuring the aerosol absorption coefficient of the measuring device.A measuring device system was set up;the system device was debugged several times and the orthogonality of the light in the measuring system was verified.The dissertation uses the lock-in amplifier to filter and amplify the interference signal of the experimental system.The appropriate optical film materials are selected as experimental objects and experiments are conducted.The experimental data of the measurement system are analyzed and processed using Matlab.Compared andverified the experimental data.