Three-dimensional transfer functions

The optical transfer function (OTF) is widely used to investigate the focusing and imaging properties of an optical system, including image modeling, comparison of relative imaging performance, and image reconstruction. An optical system can form a three-dimensional (3-D) image of a 3-D object, and the 3-D OTF is a useful approach to investigating the behaviour. The 3-D transfer function is particularly useful for study of image formation in confocal and interference microscopes. As the OTF represents the power spectral density it is also useful for studying beam propagation and scattering. The connection with the ambiguity function is also described.