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2012
Conference Paper
Titel
Design of an optical position detection unit for fast 2D-MOEMS scanners
Abstract
Recently, we have developed compact modules comprising optical position sensing, and driver electronics, with closed loop control, which can measure the trajectory of resonantly driven 2D-micro-scanner mirrors. In this contribution we present the optical design of the position sensing unit and highlight various critical aspects. Basically position encoding is obtained using trigger signals generated when a fast photodiode is hit by a laser beam reflected from the backside of the mirror. This approach can also be used in the case of 2D-mirrors. In our device the backside of the mirror is hit by two crossed orthogonal laser beams, whose reflections pass cylindrical mirrors in order to suppress the orthogonal dimension. Mirror deflection around one axis is compensated at the plane of the detection diodes while deflection around the other axis leads to a linear displacement of the beam. The optical design of the unit has to provide the optimal compromise between the require ments for small size and simplicity on the one hand and optical accuracy on the other.
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