Re: [ATM] Compensating sag of the truss frame by flexibility in the mirror cell

[Ross Sackett <rsackett00@yahoo.com>]

--- Robert Houdart <robert.houdart@cruxis.be> wrote:
...
> By appropriately choosing the properties of the
> mirror cell support
> beams, it is perfectly possible to compensate the
> 0.3 mm sag of the
> upper cage by tilting the mirror on its support
> beams. In other words,
> the tiny deformations of the mirror cell will make
> the focal point
> follow the sag of the upper cage.

I do like your idea very much, but I don't think most
of us regularly collimate our Newtonians to an axial
error within 0.3 mm (am I wrong about that?).  Would
there be much point in compensating for a sag much
smaller than the likely collimation error?

Instead of fiddling with the cell structure itself,
could you get the same effect by controlling the
springiness of the sling (for those who still use
them) or the +/- 45 degree edge supports?  That way,
instead of tilting the mirror you let it sag parallel
to the UTA (as in the original Serrurier
double-truss).

Ross


 
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