We describe a high-precision angle sensor and a new calibration system for calibrating the linearity error of an angle sensor under <i>in situ</i> conditions without the need for accurate reference instruments. To achieve accuracy in the nanoradian (nrad) order, we elongated the critical-angle prism to increase the sensitivity, and we added a thermal controller to the angle sensor. This served to suppress thermal drift of the light source to improve stability. The proposed angle sensor demonstrated a stability of 3 nrad over 1 min, and the maximum repeatability error of the calibration curve determined by the <i>in situ</i> self-calibration method was approximately 35 nrad with a measurement range of 500 μrad.
© 1998 Optical Society of America
Shizhou Zhang, Satoshi Kiyono, and Yutaka Uda, "Nanoradian Angle Sensor and In Situ Self-Calibration," Appl. Opt. 37, 4154-4159 (1998)