Dial indicators checking-up by laser interferometry

Dial indicators are mechanical gauging devices widely used for measurements in high accuracy machining. Checking-up the measuring accuracy of these devices, by classical means, is a time-consuming task for both manufacturers and users of dial indicators. Laser-based equipment for a fast and accurate checking-up of all types of dial indicators, according to international standards, is reported. This article contains the description of the equipment's operating principle, the construction of the specially designed angular transducer used for the dial indicator's hand angular movement reading, and the Michelson interferometer. The length measuring accuracy is 0.15 mu m, while the dial indicator's hand angular detection accuracy is 0.25 degrees. (C) 1996 American Institute of Physics.