Re: [ATM] Anastigmat

["Richard F.L.R. Snashall" <rflrs@rcn.com>]

Richard F.L.R. Snashall wrote:
> That may not necessarily be the case.  For example, going
> back to the original question (280 mm f/7.5, using only
> K5 and F2):
Perhaps more realistically, suppose you just happen to have
some glass that is roughly made up for the prescription:

Surf     Radius  Thickness   Glass  Diameter

 STO   Infinity   -4.25862             203.2
   2    1214.09     19.812     BK7   206.248
   3   -1300.45       12.7      F4   206.248
   4   Infinity   2838.569           206.248
 IMA  -1052.885                           42

You'd find that the Visual Strehl for this f/14.1
doublet runs from 0.6688 in the field center to
0.3615 at the edge (0.42 degrees). The total length
is about 2871 mm.

Now, suppose you ignore the directions on the box... er...
the current curves.  Grind both curves of the BK7 piece
to the same curvature; also mate the F4 to it and put a
small convexity on the flatter side.  Hard part: construct
a 130 mm diameter cemented/oiled doublet to go with it:

    http://users.rcn.com/rflrs/Ptz10-44x.atm   ATMOS input file
    http://users.rcn.com/rflrs/Ptz10-44x.len   OSLO input file
    http://users.rcn.com/rflrs/Ptz10-44x.txt   TEXT prescription
    http://users.rcn.com/rflrs/Ptz10-44x.zmx   ZEMAX input file

This ends up being just about f/8.  The Visual Strehl now runs
from 0.6558 in the field center to 0.6439 at the edge (0.74
degrees).  The total length is now 2276 mm. 

Jerry, have you finished that write-up yet?  It's now 2-0 in
my favor!
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