Parabolic reflectors are pretty handy devices ... suitable commercial dishes aren’t that hard to come by. But a big, shiny mirror for your solar death-ray needs is another matter, which is ...

Parabolic reflectors for solar applications are nice ... After you´re done with this, you end up with a nice flat mirror. Here´s where the vacuum is needed to force the film into parabolic ...

This focussing effect is very strong with WAVELENGTHs less than the aperture of the reflector, making it particularly suitable for recording high frequency sounds such as birdsong. Schematic diagram ...