Research On In-line Digital Holographic Microscopy Particle Detection And Recognition Algorithm

The interaction of aerosol and cloud exert significant effects on the radiation budget and hydrological cycle in the Earth’s climate.It’s the focus of future climate research field.Airborne particle measuring system is an important method for detection of atmospheric aerosol and cloud particles.Holographic miscopy has several advantages relative to other cloud microphysical measurement techniques: The device structure is simple and stable,and it can provide three-dimensional imaging and distinct stacked particles.Take an experimental research related cloud particle holographic microscopy measurement,and accomplished the following main contents:Establish an in-line holographic microscopy particles measurement experiment device.Analysis the ultimate resolution,magnification and depth of field of device.In view of the coaxial microscopic holographic recording distance and distance is not consistent.Represent a two-stage gradient calibration method of the distance of the record and the reconstruction.Research to improve the hologram quality method,research the method of suppressing the external noise and internal noise of the hologram reconstruction image quality,put forward a kind of cycle stripe noise suppression methods,research of coaxial holographic the zero-order diffraction and conjugate image suppression method.Research particles automatic recognition and extraction algorithm,the comparative analysis the advantages and disadvantages of various particles automatic extraction algorithm,achieve an adaptive threshold selection algorithm based on grayscale and gradient according to the characteristics of the hologram reappear.The gray gradient auto-focusing algorithm and the wavelet transform auto-focusing algorithm are studied.The effectiveness and anti-noise of the two auto-focusing algorithms are analyzed through the actual experimental results.The two-plane standard particle field is measured by the experimental system built in this paper,and carry out confirmatory experiment by using standard particle.Using atomizer atomized distilled water to simulate the cloud particle measurement environment.The particle size distribution and three-dimensional spatial distribution of the atomized droplets measured by this system are obtained.