A general solution of the eikonal equation is used to derive general expressions for both the wave fronts and the caustic surface associated with an orthotomic system of rays in a homogeneous optical medium. Both wave front and caustic can be expressed as the sum of two vectors, the first being the direction vector of the ray and the second being the gradient of the arbitrary function occurring in the general solution of the eikonal equation. This vector can be determined from a knowledge of the angle characteristic function and is closely related to Herzberger’s diapoint characterization of the geometrical image.
© 1976 Optical Society of America
Orestes N. Stavroudis and Ronald C. Fronczek, "Caustic surfaces and the structure of the geometrical image," J. Opt. Soc. Am. 66, 795-800 (1976)