How to focus beam from the fresnel lens on a flat surface.
In my case, instead of producing the light beam, I am receiving the light beam. So, the beam comes from the right and then focuses at a focal point.
My problem is that I am using cylindrical fresnel lens
And light beam can come from any direction (360 deg). Therefore the focal point is in the middle of the cylinder.
I am sensing the beam, using photodiode. Since photodiode has a flat surface, if i will simply put it in the middle of the cylinder it will not absorb most of the energy of a beam. Therefore somehow I need to reflect the beam from the focal point in the center of a cylinder to the flat surface, say the bottom of a cylinder, where I could put my photodiode.
How can this be done?