[Edited: changed flat floor to hyperbolic] Probably much less effective than a hyperbolic mirror still this may be a cost effective solution for concentrating light to a single point, with no moving parts.
A [[two way mirror]] hyperbolic dome is set above a mirror floor. The dome (as its name applies) faces down. [Edited: adding floor shape]. The floor consists of a hyperbolic mirror which will reflect any light hitting it upward and somewhat towards the higest part of the dome.
Sunlight coming from any angle will enter the dome passing through its semi transparent glass and hitting the floor mirror.
It will then be reflected back to the inside part of the dome which refelects it to the center of the hyperbola.
Since on most of the globe, the sun is always to one side (North for Africa Australia and South Amerca, South for the northern hemisphere) only half a dome is needed, the sunlight would reach the floor directly without passing through any glass, and would then be reflected to the dome, which has an internal mirror that is fully reflective, directing this light to focal point.
Since this is halfbakery, I expect people to come up with improvements. No need to tell me how terrible this idea is because of loss of light in each iteration (a. passing through dome, b. reflecting from floor, c. reflecting from inner side of dome.
I would appreciate, though, an estimate of loss from a regular (not two way) good mirror, using the second idea, or questions comaparing this to other solutions.-- pashute, Feb 04 2011 If I understand correctly, in the first idea, light passes through the dome, where some is lost, but the angle is not changed, then reflects once off the flat mirror, then once off the inside of the dome. I don't see how this is geometrically different from inverting the dome and omitting the flat mirror, except that only (at most) 1/4 of the light makes it through.-- spidermother, Feb 04 2011 Too much hyperbole surrounding this idea.-- coprocephalous, Feb 04 2011 Isn't HB hyperbakery?
I'm correcting the idea. I looked at the problem again. The light will need more than two bounces before being concentrated. For example any light hitting the floor too close to the dome curcumferance would be reflected from the dome at an obtuse angle, which would not return it to the center, but rather several times around the dome inside, until finally reaching the ground and back from the dome to the focal point.
So instead I'm adding a hyperbolic bottom mirror which always sends the light directly upwards.-- pashute, Feb 05 2011 Can anybody estimate what percentage of light and energy a two way mirror absorbs when passing the light through it?
Same question for a regular mirror. How much energy is typically absorbed by a mirror, and how much of the light and other radiance returned?
ADVthanksANCE-- pashute, Feb 11 2011 I finally found an expert on optics, who is working on the idea (with some changes after he explained the problems). I hope by 2012 to have a full-baked product to show, started here at HB.-- pashute, Mar 27 2011 Star-b-que?-- Zimmy, Mar 30 2011 Once you have the hyperbolic mirror, what good is the dome? The mirror will have a focal point and you can toast your marshmallows there. I suppose the dome would keep your mirror from filling up with rain and ducks.-- bungston, Mar 30 2011 random, halfbakery