From: "Richard F.L.R. Snashall" 
To:  atm{at}shore.net
Reply-To: "Richard F.L.R. Snashall" 




Dan Chaffee wrote:
> Rick,
> I looked at a couple of these designs (the last two) and they
> show great on axis spots with the last one having the better off-axis
> wavefront. The only thing I wonder about is how doable they
> are. For example, I decreased the radius of R6 by 2mm and
> got a strehl barely diffraction limited. Have you ever gotten
> a 5m  radius accurate to within 2mm in your lens work?
> Seems like you'd have to chi-chi back and forth for eons.
>

The tolerances on the external radii are tight, but the analysis I did in
ZEMAX does not indicate they are that tight.  With the following:

        0.5 mm thickness on the glass
        0.025 mm thickness on the air space
        0.005 mm sagitta on the external radii
        0.02 mm sagitta on the internal radii

the performance on the slowest version was still diffraction limited.  I
did a Monte Carlo set of 100, using parabolic statistics.  The worst case
showed a Strehl ratio of 0.813 at the edge, but that case had a change in
radius on the last surface of about 47 mm.

Why do the two modelling methods come up with such a gross difference?

        Rick S.




> Dan Chaffee
>
>
>
>

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