[Author Prev][Author Next][Thread Prev][Thread Next][Author Index][Thread Index]
Re: [ATM] Corrector/reducer for a fast Newtonian
David Whysong wrote:
>It is possible to design a combination focal reducer/coma corrector. I
>found one design online at
>http://www.astro.hr/mace2002/Report/MACE2002_final.PDF - look on pages
>63 and 67. This could be used, but it appears that fabrication would
>be difficult and/or expensive. The design is:
>
>Five lens focal reducer, designed for a 1m f/3 paraboloid:
>(Design from a paper by Zeljko Andreic)
>
>SURFACE RADIUS THICKNESS APERTURE RADIUS GLASS SPECIAL
>OBJ -- 5.6743e+19 8.4186e+17 AIR
>
>AST -5.8830e+3 -2.7197e+03 361.897150 A REFLECT *
>2 -320.748335 V -6.878973 70.000000 BK7 C
>3 -202.021812 V -70.677574 70.000000 AIR
>4 -310.258760 V -14.475886 65.000000 F6 C
>5 4.3789e+03 V -50.665601 65.000000 AIR
>6 -443.950052 V -18.094858 53.000000 BK7 C
>7 1.7508e+03 V -5.066560 53.000000 SF11 C
>8 -144.758860 V -14.475886 53.000000 LAFN28 C
>9 -2.8344e+03 V -49.830000 53.000000 AIR
>10 -- -- 36.000000 BK7 C
>11 -- -- 36.000000 AIR
>IMS -- -0.001395 35.780712 S
>
>
>So, any comments, criticisms, or suggestions?
>
I tend to agree with Mike. This design seems a bit far from optimal.
I tried to mimic the results with very little success. About the
closest I could come was:
SRF RADIUS THICKNESS APERTURE RADIUS GLASS SPE NOTE
OBJ -- 1.0000e+20 1.4575e+18 AIR
AST -5.8830e+03 -2.7197e+03 361.735000 AS REFLECT *
2 -345.504000 -7.000000 70.000000 N-BK7 C
3 -225.060200 -44.888490 70.000000 P AIR
4 -622.206200 -11.000000 67.000000 O_S-TIM6 C
5 2.8941e+03 -80.578420 67.000000 P AIR
6 -231.903800 -15.000000 54.000000 N-BK7 C
7 531.518400 -5.500000 54.000000 P SF11 C
8 -275.008000 -11.500000 54.000000 P N-LAF34 C
9 2.6799e+03 -50.000319 54.000000 P AIR
Schott now has N-SF11, but OSLO doesn't seem to have caught up yet.
I didn't model the vestigial lens; the design should now fit into
OSLO-EDU/OSLO-LT.
I was able to get smaller RMS spot size, but the spot shape was not
like the original. This design has some weird tweeks in the merit
function in the attempt to match the original, but lost even more
at the field center. The article was a bit confusing with respect
to spot size; what was designated as "Geometric Spot Size" appears
to be what ZEMAX calls "RMS Radius".
_______________________________________________
ATM mailing list http://www.atmlist.net/