[ATM] SEC: UNCLASSIFIED:-Re: Plop Help

[jonah at eecs.berkeley.edu (Jeff Anderson-Lee)]

Andrew.Martyn@defence.gov.au wrote:

>Mark and Jeff, thank you for your parameters for running plop to design the
>six point cell with one point at the centre and the other five in a ring
>around it. Both your approaches gave very similar results within 1%. Mark,
>as you said the results are worse than a 6 point cell in a ring and only
>about 20% better than a 4 point cell. Interesting as intuitively I would
>have though a design with one centre point and a ring would have better
>than a single ring.
>

Plop takes into account the sagging that goes on and allows you to 
refocus to compensate.  Thus, with a six point ring and no central 
support you have better support arounf the edge of the mirror (where it 
matters more) and the central sag is compensated by refocusing.

With a five point ring plus center support, the points on the outer ring 
are wider apart, hence there is more sagging radially between the 
supports, which cannot be refocused away.

Jeff