Simultaneous Cartesian coordinate display of defocused optical transfer functions

We show that by using a binary spatial filter and a square-law detector we can display all the defocused optical transfer functions (OTF's) in a given study in a single picture. The resulting unique picture has as its horizontal coordinates the spatial frequency and as its vertical coordinates the amount of defocus. The gray-level variations are proportional to the modulus of the OTF, that is, the modulation transfer function. Numerical simulations are included.