Original poster: Jim Lux <jimlux@xxxxxxxxxxxxx> At 06:31 PM 10/13/2006, Tesla list wrote:
Original poster: "Peter Terren" <pterren@xxxxxxxxxxxx>I have already obtained two decent first surface mirrors from Terry's suggested eBay source. I had wondered about simply epoxying the non-stressed mirror to the stressed mirror but the rebalancing may be an issue. After I had ordered these mirrors I remodelled the mirror so that one support is a bit flexible. That fixed the distortion of the flex but not the slight double image from the rear surface mirror. It is only a minor issue at present as my photos are now in better focus.I haven't thought about any more exotic types of mirrors.
polished metal. Aluminum is something like 95% reflective if you get it to a good finish. Steel can get almost as good, but even better, call around and find a place that will plate it for you (vacuum deposition of silver or aluminum might be best). Easy to get an optically good plate finish this way. We used to use it to make shatter proof first surface mirrors for movie cameras in dangerous setups (don't want shrapnel bashing that expensive rented Panavision camera) Lapping metal to an optical metal finish is easy, if time consuming. You get some of that 1000 or 2000 grit paper and stick it to your surplus granite block. Some water, and some time, and a mirror is yours.
The "pros" use Beryllium for spinning mirrors in high speed cameras(e.g. million fps and up).. low mass (reduces rotational forces) and very, very stiff. But they probably have fancy machine shops to do the cutting and polishing without killing the machinist.
I think I will save these mirrors for the "next generation" rotating mirror that I am starting to plan. Not even Terry knows about this yet but it is only a twinkle in my eye so far. Still lots to do with this one yet and am still tearing what hair I have left, out on my current meter.Peter