LIQUID-CRYSTAL TELEVISION APPLIED TO A SPECKLE CORRELATION METHOD - REAL-TIME MEASUREMENT OF THE OBJECT DISPLACEMENT

A liquid crystal television (LCTV) is used to obtain in real time the correlation value of two speckle patterns that are produced at different times by a moving rough object. The lateral displacement of the object can be measured from the correlation value that is nearly proportional to the amount of shift between the speckle patterns. It is shown that the appropriate size exists for the speckles displayed on the LCTV which has a finite display area and resolution. A clipping technique for speckle intensities is proved to be effective for the improvement in sensitivity of the method.