[ATM] How Much Aspherization

[Richard F.L.R. Snashall]

Richard F.L.R. Snashall wrote:
> On the other hand, if, instead of CeF correction, one goes for
> BdF correction (again 100 mm f/9):
>
>    http://mysite.verizon.net/rflrs/dbl05-18x.atm   ATMOS input file
>    http://mysite.verizon.net/rflrs/dbl05-18x.len   OSLO input file
>    http://mysite.verizon.net/rflrs/dbl05-18x.txt   TEXT merit listing
>    http://mysite.verizon.net/rflrs/dbl05-18x.zmx   ZEMAX input file
>
> The glass change here is to the other common flint, F2.  The
> aspherization here is a bit more, about 5.1 nm -- it still has
> the same high order correction of both coma and spherical aberration.

While the two inner radii are equal above, simplifying testing against
each other, there is need to make that spacer in the final product.
If, instead of making a spacer, one wanted to use a standard piece of
shim stock (or something built up from such), one solution is (6 inch
f/14.13):

    http://mysite.verizon.net/rflrs/dbl05-57x.atm   ATMOS input file
    http://mysite.verizon.net/rflrs/dbl05-57x.len   OSLO input file
    http://mysite.verizon.net/rflrs/dbl05-57x.txt   TEXT prescription
    http://mysite.verizon.net/rflrs/dbl05-57x.zmx   ZEMAX input file

The glass is simple here as well (K5 and F2).  This particular f/#
allows for canonical CeF color correction and a particular spacing
(0.0500") between the lenses at a mean diameter.

The figuring here is about a half a nanometer.  While this figuring
specifically makes the third order spherical aberration to offset
the higher order spherical aberration (in green), at the same time
the third order OSC offsets the higher order OSC (again, in green)
in this design.  I included a copy of the merit function listing
that demonstrate this:

    http://mysite.verizon.net/rflrs/dbl05-57x-mf.txt   TEXT merit listing


For those with a pure metric bent, I have included the scaled version
in text form (150 mm f/14.13):

    http://mysite.verizon.net/rflrs/dbl05-57y.txt   TEXT prescription

The spacing for the metric version is 1.250 mm, as one would expect.