Re: Lenses Are On Order

[Tom Droege <droege@fnal.gov>]

At some point Elliot asked me about the filters.  I told him the 
thickness, and it sounded like there was no problem.  Note that I
am using the filter for the window into the camera head.  I plan 
to "glue" it in place.  I used moderate melting point wax to 
assemble the prototype.  I will worry about it migrating for the
production models.  Wax is nice to put things together in that 
you can just put everything in a temperature controlled oven and
take it apart.  I have a source for wax with closely defined 
melting point.  It is also nice in that it "creeps" and will take
up a lot of differences in thermal expansion.

Elliot's design is not much different than the camera lenses we
are now using.  I think they also have five elements.  But I have
given away all the boxes, wich had a lens picture on them.

Tom Droege

At 08:56 PM 4/22/98 -0700, you wrote:
>
>I took another look at the design on the web page earlier this week,
>and had a concern regarding the windows and filters.  I'm not an optical
>expert and I tried to make some sense of some optics books, but just
>came up with questions.
>
>In looking at the design, the image is presented directly to the focal
>plane, without the chip window, the "dewar" window, and the filter glass.
>Holding a straight edge up to the screen the design appears to have the
>rays approach the focal plane at a greater angle than with a simple
>doublet. My concern is that this greater angle of convergence may increase
>the spherical abberation of the system when the windows are in place,
>and cause the performance to be less than calculated.
>
>Can someone comment if the additional flat elements are of no concern,
>or can the computer design be rerun with the extra elements in place to 
>see if it changes the optimization?
>
>-Ron Wickersham
>
>On Wed, 22 Apr 1998, Tom Droege wrote:
>
>> The subject says it.  I have grabbed the Tiger by 
>> the tail, and we are now in for a ride with our very
>> own optics.  Let's hope it is a good decision.  40 
>> lens sets are on order.  We have not yet ordered the
>> spacers, so there is still a chance to change the 
>> mix of filters.  I plan to order:
>> 6  BVRI  sets
>> 8  VI    sets
>> 
>> 
>
>
>