Re: Lenses Are On Order

[Ron Wickersham <rjw@alembic.com>]

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
> 
>