Laser interferometer using thin film photodetector

Novel thin film photodiode is proposed. The active layer is thinner than the wavelength of the incident light. A part of the incident light beam is detected and the rest passes through the thin film photodiode without the absorption. Being inserted in the optical field, this sensor can detect the intensity profile formed along the propagating direction of the laser beam. This function is applied to construct the new interferometer detecting the intensity profile of the standing wave produced by the incoming and the reflected laser beams.