Focus Error Measurement System: Practical Design Considerations

Abstract

A detailed study of the practical design considerations for a focus error measurement system through numerical simulations, based on ABCD ray matrix for Gaussian beams, is presented. The results obtained can be applied in an equivalent way to the cases of reflection or transmission measurement, since these are identical by means of a change of variables. In all cases, the calculations consider the actual shape of the detector used, since these have gaps that separate the quadrants, affecting their efficiency. The distances involved between the optical components are swept in order to study the behavior of the sensitivity, maximizing it depending on the application.