Aberrations of a sequence of conic mirrors.

An interesting class of optical systems consists of conic mirrors arranged so that each mirror shares at least one focus with the optically adjacent mirrors. This paper presents simple results for several of the aberrations largely independent of the details of the configuration. Results are presented for sine law violation and third order astigmatism when the images are located at the focii of the mirrors and for astigmatism and distortion when the pupils are located at the foci. In both cases the system is equivalent to a single conic mirror having the same magnification and focal length. It is shown that there are configurations for which both the images and the pupils lie at foci, and for these all the above results apply. The exact shape of the image surface is obtained for such a system in which all the mirrors are parabolas.