Further considerations of defocus rangefinders

摘要

This article follows a previous one that used a geometrical optics approach to analyse the operation of a defocus rangefinder system. In it, procedures were developed to enable range estimation to be made from width measurements of the blur profile when the temporally incoherent light source on the object was small and of unknown finite width. In this article, it is shown that the same procedures can be used for spatially incoherent monochromatic and quasi-monochromatic light sources in the presence of diffraction provided some constraints are met.