Study of position resolution with COPS

We describe an optical beam sensing device that can measure transverse displacements with accuracy of a few microns. An analog readout prototype with a set of four linear CCD arrays arranged around a square aperture, and illuminated by a cross-hair laser, was built and tested by the authors. Performance tests results demonstrate a linearity better than 5 μm throughout an active transverse range of over 20 mm. The reproducibility of the measurements was better than 2 μm. Long-term stability is 5 μm.