Abstract
A study is made on the fundamental properties of amplitude filter-the filter that gives an amplitude distribution over the exit pupil-defined by the equation
T(s)=as2+(1-a/2)
where a is a constant of the value 2_??_a_??_-2.
Fraunhofer diffraction patterns obtained with this filter are investigated in regard to the diffraction patterns on the focal plane, the optical transfer function of the slit aperture, and the encircled energy (or total illumination) in the diffraction image. The first two are analytically calculated and the third is evaluated numerically by the use of the Gaussian quadrature method for various values of parameter a.
