EVALUATION METHOD FOR FREQUENCY-CHARACTERISTICS OF LINEAR-ACTUATORS IN THE SUB-MU-M STROKE RANGE USING A MODIFIED MICHELSON-TYPE INTERFEROMETER

A modified Michelson-type interferometer is used for the evaluation of the frequency characteristics of linear actuators in the sub-mu m str oke range. The vibratory motion of a linear actuator is detected by qu adrature signals from the interferometer. The method is based on a pre viously proposed technique as a method for the evaluation of accelerat ion pick-ups in international standard (ISO). The scope of measurement is investigated experimentally. The measurable minimum stroke of actu ator motion is restricted by the reliability of quadrature signal meas urement and is essential at 25 nm. The maximum frequency or velocity o f the actuator motion is restricted by the sampling speed of the digit al recorder. The maximum velocity of measurement is confirmed up to 1 ms(-1).