MOVING DISPLACEMENT MEASURING APPARATUS USED I/Q HETERODYNE INTERFEROMETER

摘要

PURPOSE: A moving displacement measuring apparatus used an I/Q heterodyne interferometer is provided to measure an exact moving displacement when operating a stage in which a moving object is positioned at a high speed by simplifying a circuit for determining a position of the moving object and by continuously chasing a phase trace of the moving object. CONSTITUTION: A moving displacement measuring apparatus used I/Q heterodyne interferometer includes a first mode amplifier(200) and a second mode amplifier(210), a first mode comparator(220) and a second mode comparator(230), a moving period detecting part(240), and a moving displacement calculating part(250). The first mode amplifier(200) and the second mode amplifier(210) are used for amplifying a first moving detecting signal and a second moving detecting signal. The first mode comparator(220) and the second mode comparator(230) compare the first moving detecting signal and the second moving detecting signal with a reference voltage level so as to output a high level pulse signal or a low level pulse signal according to the result of the comparison.