Re: [ATM] A two way null test for convex hyperboloids

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

Mauritz Andersson wrote:

>>Richard F.L.R. Snashall wrote:
>>    
>>
>...
>  
>
>>However, if I have finally gotten rid of that, I did have a question
>>about the convergence.
>>If I do make the two radii the same (1374.6) and one of them (the
>>reflector in the test)
>>has a conic constant of  -5.907, the other has (again, if I have done
>>this right) a conic
>>constant of -3.628.  But symmetry would suggest that the conics should
>>have the same
>>conic constant.  What, in your scenario, forces the two to the required
>>conic constants?
>>    
>>
>
>Very good question!
>The constraint is that there should be a null in both directions.
>Your example gives a null in one direction but not in the reversed case.
>It seems as imposing complete symmetry _and_ a null in both directions
>gives too much constraint to find solutions. (Actually for BK7, and
>for this particular example, it does work if one allows for the
>thickness of the lens to vary, there happens to be a symmetric
>solution with a lens thickness of  54.1 mm.) Breaking symmetry gives
>more degrees of freedom.
>
>/Mauritz
>
>  
>
It took a while to set it up in ZEMAX, with two configurations.  The
hard part was setting up
the pickups.  But indeed, with that refractive index, radii, and
thicknesses, ZEMAX also comes
up with those conic constants as having minimal RMS OPD.

_______________________________________________
ATM mailing list http://www.atmlist.net/