[Raytrace] A real world application

[Michael Peck]

At 18:10 12/28/2001 -0500, Peter Chen wrote:
>Pressmann-Camichel
>
>       Any idea who those folks are?   I have never come across any 
> reference to these names except in Rutten and van Venrooij.

Peter (& group):

I'm going to split this into two responses.

Henri Camichel was a modestly renowned French astronomer (20th century). A 
Google search turns up a fair amount of biographical information on the 
web, none of which say anything about his work as a telescope designer. 
Must have been a casual hobby. I assume this is the right Camichel. I have 
nothing on Pressmann.

>        I plugged your design into Zemax.  I noticed that the spot diagram 
> is fairly big, consisting of a several micron spot with a faint outer 
> ring.  This persists even after optimization.   I puzzled over the cause 
> of the ring.  My guess is it must be caused by those high order spherical 
> aberrations that you mentioned.

Is that with or without the high order asphere coefficients? Without them 
this design is definitely well short of diffraction limited. One possible 
problem is that OSLO gives you about a half dozen menu choices for setting 
up a generalized asphere. Zemax probably has more than that, and it's 
entirely possible a Zemax prescription will look completely different from 
an OSLO one. If Peter Smith is willing and you're still interested maybe we 
can figure out how to reconcile a Zemax design with the one I provided from 
OSLO and move on from there.

And yes, a geometric spot diagram that has a tight core with rays scattered 
much farther out can be a sign of uncorrected high order aberrations. There 
are better diagnostics than geometric spot diagrams though. I like to look 
at ray fan plots, OPD curves, or longitudinal spherical aberration plots. 
OSLO has a taskbar button that plots several useful pieces of information 
in a single multi-paned window. They call it a "ray intercept curves analysis".

Mike Peck


_________________

Michael Peck
email mpeck1@ix.netcom.com
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