
11
FOURIER OPTICS
We noted in Chapter 8 that the Fresnel–Kirchhoff integral is mathematically very similar to a
Fourier transform, and in fact, in the right situations, becomes exactly a Fourier transform.
In this chapter, we explore some of the applications of this relationship to certain optical
systems. Using the tools of Fourier analysis, following the techniques used to analyze lin-
ear time-invariant lters in electronics, we can describe the point-spread function (PSF) (see
Section 8.6.1) as the image of an unresolvable object. The Fourier transform of the PSF can be
called the transfer function. These functions are analogous to the impulse