An electro-optical sensor for use with a retro-reflective target (10). The light-emitting
assembly involves a LED (4) and collimating and parallel lenses (2, 4), and the sensing
assembly involves a collecting lens (5), an aperture plate (6) and a
photodiode array (7) with optional field-curvature correcting lens (8). The lens (5) abut the substrate (1) within the aperture of plate (6) so that the
entrance pupil and the
exit pupil, when viewed from the target (10), abut opposite, parallel straight-edges of the substrate (1). The
photodiode array (7) may be a linear
pixel array parallel to the substrate-surface, or may be replaced by a single, large-area
photodiode with aperture-limitation of its
field of view to a narrow fan-shape parallel to the substrate-surface. A plurality of light-emitters (77) may be used with photo-detectors (71) that have individual light-collection
optics (72, 73) with merged fields of view. The sensor can sense
golf club-head (100) movement and vehicle speed and plate number (116).