The influence that Seidel spherical aberration has on the irradiance distribution along the optical axis, or the Strehl ratio versus defocus, is expressed in terms of a differential operator. This permits us to describe separately the following two effects: a focal shift and a shape variation. We analyze two annular apodizers that reduce the shape variation of the Strehl ratio versus defocus.
© 1988 Optical Society of America
J. Ojeda-Castañeda, P. Andrés,, and A. Díaz, "Strehl ratio with low sensitivity to spherical aberration," J. Opt. Soc. Am. A 5, 1233-1236 (1988)