The metrology and applications of PSD (position sensitive detector) sensors for microrobotics

The position sensitive (or sensing) detectors (PSD) are special special monolithic PIN photodiodes featuring a series of lateral electrodes in order to achieve a 1D or 2D displacement measurement of an optical spot. Compared to the discrete array sensors, the PSD have many advantages including high positioning resolution, fast response time and very simple analogue signal conditioning circuits. This paper investigates the metrology of a two-dimensional PSD working alternately in direct or indirect (reflective) mode. The possible applications consist in precise assembly of optical MEMS micromirrors or fast tracking of an object over a pneumatic smart-surface. The first results showed a good linearity and a fast response time, which successfully enable such applications for PSD sensors.