Optical Self-Mixing Rotary Angle Sensing (OSRAS) System

In response to NavyÆs need for a novel high-accuracy, radiation-hardened, miniaturized rotary angle sensor capable of performing in space flight in a contested environment, Interlog Corporation proposes to develop a new Optical Self-Mixing Rotary Angle Sensing (OSRAS) system. Being an optical approach with the wavelength (more precisely, the frequency) traceable to NIST standards, the proposed OSRAS provides absolute angular measurement with a full-circle range of 360 degrees. The high angle measurement accuracy is one of the characteristics of typical optical interferometric metrology technologies. Serving as both the optical source and sensing head, the laser diode used for the OSRAS is very compact. Its low required power consumption far exceeds the NavyÆs requirement. The optimized laser diode driver and modulating electronics render the OSRAS high interrogation rate. The OSRAS is inherently immune to EMI and is capable of operating in contested space flight environments with wide ranges of temperature, pressure and humidity. In Phase I project, Interlog will develop the proof of concept system and demonstrate the simultaneous detection of crack and delamination. This work lays the foundation for a Phase II project that optimizes and refines the robustness and long-term stability of the system.