Geometrical Optical Calculation of Frequency Response for Systems with Coma

The usefulness of the geometrical optical treatment of frequency response is considered here for the case of coma, an aberration having odd symmetry. Calculations of frequency response and phase shift using this treatment have been made, for different orientations of incoherent line objects, in the presence of Seidel coma in different focal planes. Similar calculations have been made for higher order coma in the Gaussian focal plane. Results are also given according to a mixed treatment of frequency response. The results are compared with diffraction calculations made by Goodbody. It appears from these results that the mixed treatment leads to a smaller value of the response than that given by diffraction theory, and that the geometrical optical treatment will give errors less than about 5% when the wave-front aberration exceeds about 1.5 times the Strehl type of tolerance.