Re: ATM - Polishing Pads

[lindberg <lindberg@olywa.net>]

Richard Schwartz wrote:
> 
> I suggest that you try out the polishing pads on the BACK of the mirrors
> first.   That way, you won't be so upset with the scratches  that
> appear.

Both sides of the flats are equivalent at this point; there are no
fronts/backs yet. That comes after testing. I used polishing pads for
the first time recently and polished out a 12 1/2" pyrex mirror in
record time, at least for me. No scratches. I'm stoked.
> 
> Just out of curiosity, what is wrong with a pitch lap?

Nothing. But the pads polish FAST. Save the pitch laps for figuring.
> 
> For testing, go to Home Depot and get one of those sodium vapor energy
> conserving lamps.  They can be identified by the claim that they provide
> 100 watts of light for only 18 watts of power.   (Now if only I had a
> solar battery and power conversion unit that was 19% efficient...)
> Anyhow, those lamps are pretty good for fringe testing of flats.  They
> show up to 20 fringe (but you will never have that many, right?).

Thanks, but I have already built my interferometer using black light
fluorescent tubes and a green filter. Seems to provide adequate
illumination and it runs cool, too.
> 
> Finally, a bit of humor from my attempt to make three flats ...
> 
> Q:  What's the easiest way to make a six-inch flat?
> 
> A:  Start with an eight inch blank!
> 
> Good luck, making flats is not so easy.
> 
> . . . Richard

Thanks, Richard. Where did you run into problems? Did you finish? 
        Steve.