A Precision Angle Sensor Using a Multi-cell Photodiode Array

This paper describes a compact and precision angle sensor based on laser autocollimation. Instead of using a conventional bi-cell photodiode (PD) as the detector, a new PD array with 16 cells is specifically designed and fabricated with lithography facilities available at the university. The width of each cell is designed to be 40 μm, which is slightly smaller than the light spot size on the focal plane of the objective lens. Experimental results have shown that the sensor has a resolution of 0.01 arc-seconds and a measurement range of 2300 arc-seconds, which is approximately 15 times larger than the range of the same sensor with a bi-cell PD.