Optical transfer function of an optical system with spiral zone masks in presence of primary aberrations

• The optical transfer function studies of spiral zone lenses are presented.
• The effect of topological charge, binarization, number of zones in the pupil, on the OTF behavior, is studied numerically.
• The effects of different primary aberrations on the OTF are also analyzed.

The optical transfer function (OTF), of an optical system with spiral phase zone plate (SPZP) masks with integer and fractional topological charge has been analyzed and compared with the OTF of a system with a vortex phase mask. The OTF of an optical system with vortex mask becomes negative in a certain frequency range, while that of a system with spiral phase zone plate mask shows different characteristics and attains negative values in multiple frequency bands. The effect of primary aberrations on the characteristics of the OTF is analyzed and it has been shown that the effects of balanced astigmatism and balanced coma on OTF are asymmetric while those of balanced spherical aberration are observed to be symmetric.