抄録
Novel optical interferometers based on detecting a standing wave are realized with a newly developed ultra-thin film photodiode. The active layer of the ultra-thin film photodiode is thinner than half of the wavelength of the incident light. Only a small percentage of the incident photons are absorbed and the rest pass through the photodiode. Since the photo-sensitive layer of the photodiode is thinner than the pitch of an optical standing wave, which is the thinnest interference fringe generated by two counter-propagating beams, the standing wave is measured by inserting the ultra-thin film photodiode in the optical field. Taking advantage of this function, two kinds of compact interferometers are realized. One requires the mirror on the sample surface and the other can use the rough surface. The sensor package can be small not using the wave-guide. The principle, design, fabrication process, and performance as a displacement sensor are described.
