Study On Topography Measurement Based On Electronic Speckle Interferometry

With the development of science and technology and the continuous innovation of manufacturing technology,the technology of topography measurement is more and more widely used in product design,quality inspection,national defense military and other fields,and the accuracy requirements are getting higher and higher.As an important optical measurement technology,electronic speckle interferometry has the advantages of non-contact measurement,full-field measurement,high measurement accuracy and high sensitivity,and has been highly valued by researchers.In recent years,with the continuous advancement of laser technology and computer technology,electronic speckle interferometry technology has developed rapidly and has become an important branch in the field of optical measurement.The paper combined the electronic speckle interferometry technique with the Fourier transform method and the phase shifting method to measure topography of objects,analyzed the theoretical knowledge of key technologies and conducted experimental researches,and set up an optical path system for topography measurement which could achieve non-contact and high-precision based on electronic speckle interferometry.The paper mainly includes the following contents:1)According to the typical optical path and principles of measurement method of electronic speckle interferometry,researched the measurement principles of carrier modulation morphology and topography measurement,which were based on Fourier transform and phase shifting,respectively,and designed the optical path system of topography measurement based on electronic speckle interferometry2)Analyzed the characteristics of different generation modes of speckle interference fringe pattern,and selected the subtraction mode as the fringe pattern generation mode of the experimental optical path system according to the actual processing effect.3)According to the characteristics of the speckle interference fringe pattern,researched on contrast enhancement and filtering processing.Disposed the images of the speckle interference fringe pattern by using different contrast enhancement methods and filtering algoritlims and designed a pre-processing scheme that first used gray transformation and histogram equalization and then used Winner adaptive filtering.4)According to the theories of Fourier transform and phase shifting,obtained the phase information of speckle interference fringe pattern in turn,and analyzed and compared the two methods of Fourier transform and phase shift based on the results.5)Studied on the phase unwrapping technique of speckle interference fringe pattern,and used different phase unwrapping algorithms to unwrap the wrapped phase diagram.By eomparing the unwrapping phase diagram,the quality map-oriented method or branch cutting method were selected as the unwrapping processing algorithm of the experimental optical system.6)Constructed optical path of experimental system,including selection of devices,construction and debugging of light path and carried out the carrier modulation topography measurement experiments and the topography measurement experiments based on Fourier transform method and phase shifting method,respectively.Verified the correctness of theoretical analysis and the feasibility of system construction scheme,analyzed the error sources of optical path of experimental system,proposed the improvement measures.