Study Of Shape And Deformation Measurement Technique Based On Electronic Speckle Pattern Interferometry

Electronic speckle pattern interferometry(ESPI) is an important branch of optical measurement techniques. ESPI which uses speckle pattern analysis for deformation field measurement has the characteristics of non-contact, whole field and high-precision. And this technology has become an important technique in the recent twenty years. ESPI can measure the object, through forming a carrier pattern on the object surface(Carrier pattern modulation), analyze the relation between displacement field and altitude of the object surface.The method have high measure sensitivity because it is based on interference of light. Electronic speckle pattern shape interferometry based on the traditional ESPI, have the virtue of ESPI. In this dissertation, electronic speckle shape and deformation measurement by using Fourier transform(FTM) is detailedly discussed. The main contents are described as the following:1. The origin, producing method and correlative concept is introduced. A review of development of speckle metrology is presented. Electronic speckle pattern interferometry principle and phase measurement technology in the speckle interferes is introduced2. A review of development of the shape and deformation measurement. Several shape measurement methods are introduced ,especially is the combination of ESPI carrier modulation method and FTM.3. Based on the basic principles of the shape measurement by carrier modulation in Electronic Speckle Patterns Interferometry (ESPI) , a carrier pattern containing altitude information are formed on the object surface when the test object is tilted a small angle. Points on the surface of the object are displaced a distance when the test object is rotated. The phase introduced by the deformation and that introduced by the deflection of the object are compared. We found that the carrier is introduced by the out-of plane displacement and the phase containing altitude information is contributed by the in-plane displacement. Based on the relationship several ESPI methods for shape measurement by using carrier modulation are discussed. The typical ESPI system is effective because the carrier pattern containing altitude information are clear. so the phase of the object can be derived by Fourier transform easily, which is proved by the experimental results.4. Involved in the design of a new type of large shear square prism, and use this new prisme to a series of deformation and shape experiments with good results based on ESPI. Experiments also confirmed the great advantage of this new type prism is effective use of light intensity transmittance, but also has the advantage of cheap. Conducive to achieving product and scale.