Investigation of speckle displacement effects on speckle interferometry

In the experimental set-up for measuring temperature fields in fluid flows by using speckle interferometry ( e.g. electronic speckle pattern interferometry or phase shift speckle interferometry ), the part of the; arrangement for the object light beam is just like a subjective speckle photographic system. Therefore, in general, speckle displacements are generated. The speckle displacements can change the intensity distribution of spatial speckle fields. As a result, the intensity distribution of a speckle interferogram is also changed. In this paper the effect of speckle displacements on the speckle interferometry is analyzed and discussed in detail. A physical model and mathematical treatment for the effect are proposed. Experimental results are shown. A method for elimination of the effect is provided. Using the provided method, the temperature measurement error of speckle interferometry can be reduced and the measurement accuracy can also be increased.