Wave optics in gravitational lensing

This review on "wave optics in gravitational lensing" includes a derivation of the diffraction integral formula for the lensed wave amplitude using th e path integral ( 2), reduction of this formula to the geometric optics app roximation in the short wavelength limit along with discussion on the condi tion that the wave effects become important ( 3), examples of wave effects for a point-mass lens and the fold caustic ( 4), and a numerical method of evaluating the diffraction integral ( 5).