ABSTRACT
Optical systems can be considered as linear systems, which, therefore, can be analyzed by using Fourier transforms. Systematic understanding of many optical characteristics of coherent and incoherent imaging systems is performed. This chapter introduces the optical transfer functions (OTF) in the coherent and incoherent imaging systems to discuss the imaging properties. OTF describes the frequency response for all spatial frequencies, but the resolving power shows only the frequency limit based on the Rayleigh criterion. The intensity of the image in the coherent imaging is given by the squared absolute value of the amplitude of the image. In the incoherent imaging system, the image intensity is given by the convolution of the object intensity and the intensity of the point response function. The chapter discusses the angular spectrum method for wave propagation analysis. It presents the diffraction in 3-D space based on 3-D spectrum.
