Video from rimstar.org about Fresnel lenses. He discusses the question of which side of the lens should face the sun. From about 2:20 to ...

I have been watching the progress of сергей юрко on YouTube with his very interesting solar trough project. сергей юрко is Sergey Brisk...

I had written in fresnel lens about wanting to determine the focal length of a large Fresnel lens removed from an old rear projection telev...