Optical feedback into a superluminescent diode cavity for absolute distance measurements

The development of accurate absolute distance interferometers is a long-term research goal. The key impact of this paper is the development of an absolute distance interferometer based on the optical feedback into a superluminescent diode cavity. The proposed approach employs a two arms interferometer feeds by a superluminescent diode. Thanks to the optical feedback, we obtained huge interference fringes even with diffusive targets. The proposed signal processing exploits a zero-crossing approach to determine the absolute target position. Preliminary results show a ratio between measurement uncertainty and range of about 50 ppm.