[ATM] Asphere- Surface deformation- Spherical polishing

["Don Clement" <clement.focuser@verizon.net>]

Aspheric optics might be produced with a surface deformation and spherical
polishing without flexing the entire optic. Imagine for a moment a Pyrex
blank (or some other nonzero-CTE blank) polished to a sphere. Now hold a
finger to the surface, remove finger and examine using foucalt tester. A
local high area can be seen. So if there were a way to apply heat  to local
areas of just the surface then polish with a full contact sphere, an asphere
could be produced without flexing the entire optic. Note that this is
different from controlling the figure by heating from the backside. Local
surface heating might be as simple as creating a thermal mat with specific
heated areas, contact mat to polished optic surface, removing and polishing
to a sphere with a full contact lap. Because glass has such poor thermal
conductivity the local heating from the mat would have a thermal
persistence, similar to the phosphor used in a crt. With this or other
method of heating  just the surface, an ultra smooth asphere might be made
by with spherical polishing and no flexing.

Don Clement
Running Springs, California

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