Research Of Holographic Imaging For Atmospheric Particles

In recent years, air pollution becomes more and more serious, atmospheric particles make serious influence on the industrial production and daily life, so the measurement and analysis of atmospheric particles significant for the improvement of the environment and the quality of life. Based on the digital holographic to measure particles, the spatial distribution and information about particles can be achieved in this thesis.The digital holographic recording and reconstruction theory are researched in this thesis, and two kinds of reconstruction algorithm are achieved. What’ more, plane wave records and plane wave reconstruction algorithm of the particle field digital-in-line holographic are studyed. The digital hologram is reconstructed with convolution algorithm, then the reconstruction images denoised with image processing techniques to get the clear image edge.With the wavelet modulus maxima edge detection algorithm, particles edge can be detected. Then a series of image processing methods are needed to get the clear edge. The focusing and defocusing particles should be distinguished. Using centroid approeximation algorithm to obtain the two-dimensional coordinates of particles. With 8-chain code method to get the equivalent diameter of the particles and reproduce in the three-dimensional coordinate, the spatial distribution of particles is acquired.The experimental system is designed and constructed in this thesis. Hologram of metal wire, particle field and water droplets are shot, and clear reconstruction images are achieved with convolution algorithm.