Calibration System with Microinch Precision at Temperatures to 500°C

Abstract

A reference system for the evaluation and calibration of microdisplacement readout systems is described. The basic reference system consists of several pieces of precision readout and positioning equipment, a high temperature test chamber, and a specially designed linkage system. The case temperature of the transducer under calibration is maintained constant to within ±0.5°C for temperatures to 500°C. A quartz and Invar linkage system provides a minimum expansion method of coupling linear motion, through a heat shield, from the readout equipment to the transducer located in a test chamber. The reference system is periodically calibrated in the plant Metrology Laboratory and a basic reference system precision of ±0.3% or better for operational ranges from 0.004 to 0.500 in. has been established.