Digital filtering of speckle-photography data

Optical methods for nondestructive analysis of strain fields are continuing to generate a great deal of interest among experimentalists; the potential of these methods is considered to be great. One persistent obstacle to the accuracy of such methods is the contamination of the data by ‘optical noise’. This paper describes a digital method which allows extensive reduction of noise components from data records obtained in point-by-point interrogation of double-exposure speckle photographs. The computations prove to be inexpensive and effective. Sample results are given and further applications are suggested.