ATM Spherical Primaries

[Anthony Stillman <atmer@flash.net>]

Following the "large mirror" thread, I thought of and then finally got
around to looking for, two articles of interest.

The first  paper  "Prime focus correctors for the spherical mirror"  by
Jones and James Applied Optics Vol. 31 No. 22 is from 1992.  It discusses a
four element single glass (BK7) lens system placed near the focal plane.
The abstract reads;

"The aberration of a spherical mirror of moderate aperture (~f/5) can be
corrected by a lens system near the focal plane.  A four-element lens
system is necessary to provide a satisfactory state of correction over a
full field of 0.5 deg.  The design of such a lens system is described with
emphasis on the intrinsic properties of each component and the logic behind
the choice of layout."


The second paper "All-spherical catadioptic telescope with small corrector
lenses" by Sigler Applied Optics Vol. 21, No. 15 is from 1982.  As I
vaguely recall, a  similar though less detailed article presenting this
work also appeared in "Gleanings."  The AO abstract reads;

"A well-corrected telescope with a large spherical primary mirror can be
realized by using three or four small widely spaced, corrector lenses.  An
interesting solution uses the lenses in a relay configuration which results
in an erect image, accessible real exit pupil, and an internal field stop.
Lateral color is corrected by adding a field lens at the intermediate
focus.  Polychromatic axial correction is excellent despite use of only one
type of glass.  The useful field of view is typically limited to 1 deg.
Examples are presented."


Anthony


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