Interferometers for Use as Integral Parts of Machine Tools

A simple, compact laser interferometer has been developed for use as a length-measuring transducer on various types of machine tools. The size, which is less than a 2-inch cube, and rugged construction, with all optical components glued or otherwise rigidly secured, make mounting on machine tools an inexpensive operation; the units do not interfere with normal machine operation. The design requirements of interferometers for these applications are discussed with the specific critical design features of this unit. This includes electronic as well as optical design. These interferometers have been used on both manually operated machines and automatic numerically controlled units where the interferometers act as the feedback elements. Inspection machines with their higher accuracy requirements have received most of the installations, but fabrication machine installations have also been made. The operating experience, which extends over a year on some installations, is discussed in relation to present day limitations and drawbacks. Photographs of installations with the interferometer and the actual interferometer package are shown.