Researches On Principles And Applications Of Optical Speckle

The development and the present status for optical speckle technique which belongs to laser measurement are introduced in this thesis. It explains the cause of formation, the categorization and the optic statistical characteristics for speckle in details, it also makes a concrete analysis of three measuring methods for optical speckle. According to this, a new optical measuring method , speckle pattern interferometry ( SPI for short ), which can be used in criminal investigation, nondestructive examination ( NDE for short) and precision measurement on line, is proposed. At the same time, it proves the feasibility and the practicability for this new method by experimental researches.In this thesis, lots of researches on applications are carried out based on the proposed method. To begin with, it is the first time to use this method for fingerprint feature extraction and information handling in our nation, therefore, a new fingerprint identification and analytical tool is applied for criminal investigation by using this method. Secondly, the physical quantity which directly reflects the situation of thermal deformation for the aluminum material can be obtained by using this method, and it presents a effective way to nondestructive examination. Furthermore, in the study of precision measurement, the displacement variation of the induced strain field for driving by piezoelectric ceramics will be measured, and we are satisfied with the results. So it gets the aim to high-accuracy survey.Thus we can come to a conclusion that speckle pattern interferometry is a new optical method for extracting small-signal ( or feeble signal ). It provides a powerfully theoretical and experimental platform for the study of automated, full-field and nondestructive measurement.