We have developed a ray‐tracing program to calculate the imaging properties of ellipsoidal and toroidal mirrors in glancing angle configurations. It has been proposed that such mirrors be used in small angle neutron scattering instruments, in order to achieve increased count rates without sacrificing angular resolution. We describe the method of calculation, including effects due to gravity, and we present a number of instructive examples of calculations for both types of mirrors. We also illustrate a practical method of reducing image degradation associated with gravitational effects. ©1996 American Institute of Physics.