Research On Digital Speckle Displacement Measurement And Tracking Techniques

Laser speckle displacement measurement technique develops on the basis of characteristics of laser speckle. The speckle metrology has many merits, such as high-accuracy, full-field, non-contact, real-time, flexible, and so on. The advance of speckle metrology is driven by its expanding and extended applications and the advance of related theory and technology. One goal of this thesis is utilizing well-developed theory to develop better speckle displacement measurement methods and obtain deepen understand of characteristics of laser speckle.Target tracking has extent applications. It is worthwhile carrying on research on laser speckle motion tracking. Another goal of this thesis is making an attempt to extent laser speckle research to this new application and to develop tracking methods for laser speckle motion.The main works and innovations of this dissertation are as follows:1. Digital speckle displacement measurement by a thresholding technique (DSDMT) has been developed by this thesis for overcoming the level-crossing-based measurement's weaknesses, such as a big sampling area, high computation complexity, liable to noise influence. Thresholding of speckle image makes a better correlation output. A fast algorithm has been developed, which reduce DSDMT's computation complexity considerably(O(N~2) to O(N)). A low-pass morphological filter has been employed to suppress noise and increase its signal-to-noise ratio(by 0.6%). DSDMT does not require multiplication operation. The improved performances of DSDMT include reduced sampling area, available to real-time applications, and easy for hardware setup.