Abstract

Digital speckle pattern interferometry (DSPI) is a means of nondestructively testing mechanical parts. This technique is very versatile, and may be used in many different ways. Applications of this testing technique include the observation and detection of object defects due to stress or strain in the part, out-of-plane object displacement, observation of resonant vibrations, and the quantitative phase mapping of object defects. Comparisons between a master part and a test part can also be performed to determine if it meets specifications. The measurement range of this technique is limited by the wavelength of light used and the number of resolution elements across the object. The limit to the range of motion measureable by DSPI is fifty waves in optical path or twenty-five waves in object movement when using a 100 x 100 element detector array. Larger departures can be measured by processing data from either two-wavelength or two-angle measurements. These last two techniques may also be used for contouring optically deep objects.

© 1985 Optical Society of America