Novel micro interferometer for length measurements

A novel micro interferometer for length and displacement measurements based on sampling an optical standing wave was developed. The interference of two laser beams propagating in opposite direction results in a sinusoidal light intensity profile, which can be detected by thin transparent photodiodes. Two detectors positioned on the optical axis of a standing wave allow bi-directional fringe counting. The operation principle of a set-up consisting of a phase sensitive transparent detector based on two integrated nip-diodes of amorphous silicon and its alloys will be discussed. Lissajous figures close to a perfect circle are recorded to demonstrate the operation principle of the new device.