Groove pitch of CPV lens is upside down to prevent contamination from dust and other outdoor conditions. CPV Fresnel lenses are 50~ 100% thicker than common Fresnel lenses. Also Groove pitch is wider for high efficiency.
Also we design to use more 3mm Optical PMMA for longer life time and to have 0.5 ~ 1.0mm groove pitch for higher solar concentration. (If groove pitch is density, then quality of image that is maginifed is clearer.If groove pitch is width, then efficince of concentration of light is higher.)
There is three choices for material of CPV lens, Poly visible, Poly visible with UV cut, and SOG. (see Poly material documet for detail)
