I have a Fresnel lens but its both sides are plain i.e.it does not have grooves (Newton Rings). It can increase the temperature upto 100 to 150 oC. I am looking for Fresnel lens with grooves that can probable increase the temperature more than 1000 oC
I guess you mean heating by sun light, concentrated by the lens on the target. In this case the most important is thermal isolation of the target (minimum losses of heat by thermal conductivity , heating in vacuum, when only radiation losses remain). You believe, that using better lens you can reduce light spot, so you can reduce target size and heat losses. But even perfect lens cannot make spot size less than the size of sun image (sun angular diameter, 0.5 deg. x focal length of lens).
More important is lens diameter. Larger diameter - larger collected light power. But you cannot make lens diameter larger than focal length. On practice, numerical aperture of the most lenses is less than 1. So, increase of lens diameter leads to increase of spot size. No sense to increase spot larger than target.
Then, the light power affect on heating speed only. In the case of good thermal isolation (adiabatic heating) even low heating power can result in big increase of target temperature.
So, the main is thermal isolation.
FRESNEL LENS EXTREME Solar 3000˚ F Sunlight Melting a Burning Stuff with the Sun - YouTube
Look at that YouTube video. I tried to post the URL, but apparently Researchgate doesn't allow that.
I have a smaller one I bought from a scientific surplus company that goes to 2000F, but they also sold a much larger one that could heat to 3000C. Perhaps they are still available on the web. The big one was about 2/3rds of a meter in diameter as I recall.
- Badges
- Science topic
- Similar topics
- Computer Communications (Networks)
- Simulators