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PLOP vs. Kriege

Started by jpcannavo, 05/11/2004 01:13PM
Posted 05/11/2004 01:13PM Opening Post
I am building a cell for a 15" X 2" F5 mirror, currently being refigured by Steve Swayze. I had already built a 9-point flotation cell as per traditional dimensions - i.e. Kiege. My question is this: With a mirror of this size, 15x2",
is there any point to using PLOP optimization to redo my flotation system so as to accomidate what I anticipate will be an excellent mirror.
Joe

16" F5 "Front Collimating" mirror cell
Posted 05/13/2004 03:05PM #1
These calculations are really entertaining, but I wonder if they reflect enough of the true situation:

It looks like PLOP assumes that equal forces are applied by each mounting point. To achieve that, not only do the bars or triangle have to pivot, but their bases also need to be connected through pivots. Do real mirror cells do this?

The mirror cell chassis typically does not have the same rotational symmetry as the mouting points. Does this cause unequal distribution of the mounting forces?

Most observation is not done at zenith. Unless the mounting points have zero friction, there will be shear forces twisting the mirror. How much do these matter?

To the extent the mirror is not supported by such shear forces, the sideways (from the mirror's point of view)component of gravity is taken up by the sling/clips, etc. How do these affect the figure?

Finally, any advice for equatorial mounts? It would seem that the edge support of the mirror would be equally as important as the rear.