Study On Micro-Digital Speckle Correlation Technique And Its Applications

As the development of the microelectronic technique, project of surface, bioengineering and medical stuff, the characteristic dimensions of the frame and device we explored are becoming smaller and smaller. We need new measure technology and platform to give valid valuation of these devices, which combines digital speckle correlation technique and micro image technique, is researched in this paper. The main contents of this thesis are as follows:1. A new high accuracy digital image correlation measurement system based on double long-focus CCD microscope is presented. This method increases the sensitivity of strain measurement from 20 με to 1 με . It provides a new no contact, large deformation, highprecision and numeralization measuring technique for the mechanical property testing of engineering material.2. The influence of the noise to measurement accuracy using digital speckle correlation method is discussed in detail. CCD noise is defined as time noise and spatial noise, and the statistical regularity of noise is presented. Based on this statistical regularity time average method is presented to eliminate the noise.3. Annular LED cold light illuminator was used to replace the oblique incidence illuminator. By this way thermal distortion caused by illuminator is erased. Compared the annular light illuminator with oblique incidence illuminator, conclusion can be drew that the illumination of annular illuminator is more homogeneous than oblique incidence illuminator. Annular illuminator also has less influence to gray level and pattern of the speckle. So it can increase the sensitivity of digital speckle correlation.4. An auto control temperature control device which adapts to micro-speckle correlation system is designed. The temperature control precision is up to one degree. Thermal distortion of slug spot weld, whose diameter is 0.8 mm, is measured using this temperature control device and micro-image-forming system.