From: "Richard F.L.R. Snashall" 
To: ATM List 
Reply-To: "Richard F.L.R. Snashall" 




Bob May wrote:
> Rick, thermal characteristic?
> Not too sure of what you are asking here so please elucidate.
> I'll note that there is a interesting thing about this design in that there
> seems to be an air to air interface as the first element.  For a doublet
> this is somewhat odd.
> Bob May

Sorry, I wasn't too clear.

Other quadruple lens systems I've seen have always been double doublets. 
Would the the temperature equalization better for those, or for all four
lenses in contact as it is here?  For this 116 mm f/15, the 40 mm thickness
may not be much, but I have pushed this design (217.5 mm f/8) where the
thickness ends up at 93 mm.

The air-to-air interface is a quirk of mine (one of many, I guess ;-).
ZEMAX comes up with a slightly different clear aperture if I just attribute
the stop to the first surface, so I put the stop as a separate surface with
a zero distance edge thickness solve.  The clear aperture is then precisely
the value I specify as "aperture".

--
Rick S.
http://users.rcn.com/rflrs

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