Abstract

We propose a new optical method for determining the optical phase term from the intensity distribution. The basic idea of the new method is as follows: Consider a simple Fourier optical setup or 4f system. An object f(x) = |f(x)| exp [jθ(x)] is put in the object plane, and the detector is inserted in the image plane. Obviously the intensity distribution I(x′) determined here does not include any phase information. However, if we use a spatial filter to modulate the spectrum distribution of the object function, the new intensity I(x′) will be related not only to the amplitude term |f (x)| but also to the phase term θ(x). The relationship between I(x′) and θ(x) is also changed by using differential filters. Therefore, the phase factor θ (x) can be obtained from a series of intensity measurements. It can be shown that the phase term of the object function can be uniquely determined by using two different modulated plates.

© 1988 Optical Society of America