Study On Surface Topography Of Micro-Structure And Position Measurement Of Micro-Sphere By Digital Holographic Microscopy Technology

Digital holographic microscopy allows fast, nondestructive, full field,high-resolution quantitative amplitude and phase contrast so that it is widely used inmany applications, such as the surface profiles measurement of the micro-structure,bio-medical, particle tracking velocity and so on. There exist two kinds of digitalholography system distinguished by the angle between the reference beam and theobject wave called off-axis and on-axis digital holography. The off-axis digitalholography is often used in the surface profiles measurement of the micro-structurewhile the on-axis structure for the particle tracking.This paper focuses on the research of the surface profiles measurement of themicro-structure and the position measurement of the micro-sphere based on the digitalholographic microscopy. The work in the thesis can be listed as follows:1. Overview of the digital holograohic microscope technology around the world.2. Discuss the method for the surface measurement of the micro-structure and theposition measurement of the micro-sphere based on the digital holographicmicroscope technology.3. Present a new method for compensate the phase aberrations by using thecooperative process of the numerical simulation of the reference wave frontand the adjustment of the reference beam. The numerical simulation of thereference wave front is used for getting the replica of the reference wave frontand the adjustment of the reference beam is used for compensating theaberrations of the setup which lead a precise measurement. Also anothermethod called the double exposure technique used for the phase aberrations.The surface profiles of two microstructures are measured for evaluating thefeasibility of the compensation method.4. A sequence of holograms is acquired using CCD with an in-line digitalholographic microscopy. Each hologram is subsequently reconstructed overseveral transverse planes to determine the location of the particles in3Dvolume at different time instants. Computer simulation of the recording andreconstruction process of a single particle is performed. The experiment isconducted for the field of diameter4.5m SiO2micro-sphere and the axial resolution is nearly10nm.