Holographic and Video Techniques Applied to Engineering Measurement

Abstract

In a brief period, lasers have developed from curiosities of the physics laboratory to tools suited to incorporation in complex instrumentation systems. One line of progress has been through the applications of holography and holographic interferometry to engineering metrology where the potential of a precision comparator is realized without a convenient means of using it. The process, however, has formed a basis for development and the progress of holographic metrology is reviewed leading to more general concepts better described as “Coherent Optical Metrology”. The authors' latest developments in this area are described where, by means of a coherent optical sampling technique, three dimensional data is coded onto an electronic video waveform. The method is based on speckle pattern interferometry with optical to electronic interfacing by means of a modified closed-circuit television arrangement. With this instrumentation, most of the measurement facilities of holography are retained without many of the inconveniences arising from photographic recording. The data is processed electronically and displayed or presented in a form suitable for viewing or to actuate a stage of process control.