On Thu, 2010-08-26 at 15:06 -0700, Speaker To-Dirt wrote: ... snip > The machine tools used in mirror grinding are not encoded to twice > the limit required on the glass as called for by Mr Nyquist. All the > optical grinders I've worked with are close to run open loop along > these lines. There is a model by which glass is removed.
The mirror-o-matic simply has a spindle that turns the mirror and an eccentric driven X that sweeps the tool (disk on top of the mirror, face to face). The Z floats and as mentioned before tends to grind a sphere. The radius is "controlled" by adjusting the tool diameter relative to the mirror. The higher tool size (~40% to 100% of mirror diameter), the flatter the radius. Also the longer the X stroke the flatter the radius. I haven't done any mirror grinding yet, but I understand the grit sessions grind a very close spherical radius, then the polish sessions polish the radius into a parabola by changing the tool size and X motion to try to selectively change the optical radius at different mirror face circles. >From the comment above, it looks like UofA tries to model all of this up front. Adding EMC2 to the mirror-o-matic could allow one to try using more complex X motion schemes, plus maintain grit and water so the machine would need less attention. > Foccult testing and Hartmann testing give you the high and low points > on a mirror. Strokes with a given grit are computed to remove the high > surfaces, and then run on a machine that may only be encoded to 0.010 > inches/tick. You run the stroke, then run another optical test, then > compute another stroke ..... You keep going until the error is within > acceptable limits. Here's the machines I worked on. > > http://mirrorlab.as.arizona.edu/ > > Andrew To see UofA make a mirror, follow the left sidebar links here: http://mirrorlab.as.arizona.edu/TECH.php -- Kirk Wallace http://www.wallacecompany.com/machine_shop/ http://www.wallacecompany.com/E45/index.html California, USA ------------------------------------------------------------------------------ Sell apps to millions through the Intel(R) Atom(Tm) Developer Program Be part of this innovative community and reach millions of netbook users worldwide. Take advantage of special opportunities to increase revenue and speed time-to-market. Join now, and jumpstart your future. http://p.sf.net/sfu/intel-atom-d2d _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
