Three mirror anastigmat focusing question

[bob prohaska]

Can a three mirror anastigmat be used in the near-field?
The problems of generating the shapes required for the
mirrors are understood to be difficult to solve. Putting
that aside for the moment, the next obvious question seems
to be focusing, thinking about supertelephoto-type applications.

Is it enough to move the optic with respect to the focal plane,
or must one also move the elements (or worse yet, re-shape
them) relative to one another to maintain minimal aberration?

The idea of a compact, lightweight uv-vis-ir imager seems appealing.
With the advent of advanced molding for optical elements it does not
seem absurd to imagine at least a few applications, provided they can
be focused at less than infinity.

Thanks for reading, and any hints or references (I've looked and found
nothing understandable on-line).

bob prohaska