Portable extended life metrology system for measuring scale displacement

Abstract

A portable extended life metrology system is disclosed. The system is of the kind which includes means for generating an interference fringe pattern as a function of a parameter to be measured, transducer apparatus for simultaneously generating three intensity-modulated optical signals, I.sub.R, I.sub.S and I.sub.T that are related to the interference fringe pattern; signal processing apparatus for accurately determining an aspect of the interference fringe pattern form the three signals; means for accumulating phase information proportional to the aspect of the interference fringe pattern; and means for converting the accumulated phase and aspect information to desired outputs indicative of the parameter to be measured. The system includes a pulsed drive circuit designed to minimize its power drain without affecting its measurement accuracy and an energy source connected by the pulsed drive circuit to a radiation source to power the same in two operative states: a low, standby mode and a higher operational mode, with incremental and self-adaptive switching therebetween. The pulsed drive circuit controls the energy per pulse, the pulse repetition rate, and returns residual energy to the energy source of the system.