RE: [ATM] Achromatic Doublet Design Help

["Robert Turner" <rbturner@charter.net>]

> I don't think that you're doing a F15 as the focal plane is
> 1200mm after the
> 50mm lens diameter.  That makes it more of a F24 design!
> I do believe that it is a diameter there rather than a radius.
> The lens curves tend to be a bit shallow with a first curve of 1000mm and
> the flint seems a bit odd with a near equal curvature on the two surfaces.
> That lens is usually bent so that the back surface is near flat.
> GSUM shows a quick starting point where the curves are
> R1 909.6mm  T1 10.67mm
> R2 -574.6mm  T2 .002mm
> R3 -531mm    T3 8.66mm
> R4 -2245.8mm
> and this looks a lot more typical of what the elements should look like.
> Bob May

Well after some help from list members I was able to read up some more and I
did the Gee Wyld program and came up with a better starting point. Then I
let OSLO optimize it. The result is a new design...

http://webpages.charter.net/astrorob/Robert_Achromat_2.len

The part I dont quite have a grasp for yet is how you determine the
thickness that will result starting from flat glass. I am going to start
from two pieces of glass square 11x11x3 cm. From which I will have to shape
into hopefully 4 inch lenses. Would I just rough in the curves to my
estimate and get an idea of my finish thickness first? Then go back with
another optimization in OSLO to determine what my final radius should be
based on what I end up with my rough cut?

I just have alot more to figure out then just going to someone and ordering
rough curves to my desired thickness. I have to start from square blocks of
glass.

Robert

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