Re: [ATM] All Spherical Telescopes

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

Hugues.Laroche@ses-astra.com wrote:

>In the sub-aperture corrector branch of this zoology ;-) you may also
>count the Icarus design:
>
>http://members.tripod.com/mipan/IcarusHome.htm
>
Impressive little monster isn't it.  However, if your budget isn't up
to that f/6.4, the following relay Cassegrain is starting to look
promising:

Surf      Radius  Thickness   Glass   Diameter
 OBJ    Infinity   Infinity                  0
 STO    Infinity   8.220453                600
   2   -5478.261      -2100  MIRROR        600
   3       -2352       1400  MIRROR   149.3496
   4    Infinity   149.9647           29.62339
   5   -526.1899         11   N-BK7         60
   6   -65.29813   17.10058                 60
   7   -55.66762        4.5      F2         60
   8   -92.90854   452.8737                 60
   9    92.90854        4.5      F2         60
  10    55.66762   10.38555                 60
  11    65.29813         11   N-BK7         60
  12    526.1899   638.6614                 60
 IMA   -316.4788                      41.86729

I started with a simple f/10 that had an interior focus 2/3 of the
way back to the primary and a secondary sized under 1/4 size.  I
added the relay elements in the path, ending up with f/-12.  It
doesn't quite get to diffraction limited.  I wonder if some other
tweek would push it over. I like the fact that the lens pairs are
mirrors of each other (except the spacing).

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