Abstract: Investigated a opto-electrical amplifier displacement composite amesdial which is composed of grating, hall element, homopolar magnet, digital caliper and converted Michelson interferometer. Three different ways of measuring tiny distance (grating amplifying displacement method, hall tiny distance transducer method and interference fringe amplifying displacement method) are applied with the equipment.

Key words: pto-electrical amplifier displacement composite amesdial, amplifying displacement method, Moire fringe, Hall voltage, interference