Design of a customized CMOS active pixel sensor for a non-diffractive beam optical encoder

Displacement and rotation sensors based on an optical principle of operation are commonly named as “optical encoders”. These encoders can reach sub-micrometrical resolution and are typically used in industrial and scientific equipment such as lathes, radars, plotters, robots, microscopes, etc. In previous papers our group introduced a new design of an optical encoder based on a non-diffractive beam and studied its performance in terms of measurement resolution and system stability under mechanical perturbations. In this paper it is proposed an improvement of the design by means of using a customized CMOS active pixel sensor (APS). The feasibility of this design is studied and demonstrated by means of two different preliminary implementations in a standard 0.5 μm channel length CMOS process, which showed a suitable linear response over three decades of light intensity.