O when will the insanity end???? I was just reading about the use of shaving mirrors over on CN and their potential use for reflector primaries.
Yeah, I had my idea of utilizing the backs of large security mirrors (some up to 64 inches diameter, which would make a nice aperture if you could figure, polish, and support it, unfortunately they tend to be way too fast (F/2 and under)).
And I've thought of other nontraditional avenues such as meniscus glass, and membranes under over/underpressure (vacuum to you other guys) tension, all of which had been though of by other people.
One of the issues here though is that the material will warp in undesirable ways as it is deformed under tension. Surface area/volume relations and all that. BUT such relations also are affected by temperature.
Soooo, instead of simply fighting such things by creating zero-expansion materials, why not take advantage of such behaviors??? That is, vary the expansion coefficient in a radial (and perhaps also thickness) gradient? A flat sheet of such material will ideally warp in such a way as to produce a usable figure all by itself, and perhaps if done right smooth out in the process, as the temperature changes.
Maybe I need a new supply of mushrooms, but it would be curious if such a thing could be done. Anyone ever heard of gradient expansion materials anywhere?
Jess Tauber
Yeah, I had my idea of utilizing the backs of large security mirrors (some up to 64 inches diameter, which would make a nice aperture if you could figure, polish, and support it, unfortunately they tend to be way too fast (F/2 and under)).
And I've thought of other nontraditional avenues such as meniscus glass, and membranes under over/underpressure (vacuum to you other guys) tension, all of which had been though of by other people.
One of the issues here though is that the material will warp in undesirable ways as it is deformed under tension. Surface area/volume relations and all that. BUT such relations also are affected by temperature.
Soooo, instead of simply fighting such things by creating zero-expansion materials, why not take advantage of such behaviors??? That is, vary the expansion coefficient in a radial (and perhaps also thickness) gradient? A flat sheet of such material will ideally warp in such a way as to produce a usable figure all by itself, and perhaps if done right smooth out in the process, as the temperature changes.
Maybe I need a new supply of mushrooms, but it would be curious if such a thing could be done. Anyone ever heard of gradient expansion materials anywhere?
Jess Tauber
