To shorten a focal distance even in a large-sized solar system.
A plurality of Fresnel lenses F1-F9 of square plate shape arranged on the same plane in such an attitude that sunlight vertically enters a plane of incidence are held by a holding frame 71. The respective Fresnel lenses F1-F9 have flat surfaces 2 on the incident side and convex surfaces on the outgoing side with a large number of prism parts 11, 12 arranged on the same plane to perform one lens action as the whole Fresnel lens. In the Fresnel lenses F1-F9, the convex surface in the prism part 11 in a first group located on the side close to an optical axis A performs a lens action when light reaching a first surface 3 is refracted by the first surface 3 to go out, and the convex surface in the prism part 12 in a second group located on the side far from the optical axis A performs a lens action when light reaching a first surface 3 is totally reflected by the first surface 3 and then refracted by a second surface 4 to go out.
COPYRIGHT: (C)2010,JPO&INPIT
Yada Yukio
Shohei Ishida
Koichi Sato
| JP2007079082A | ||||
| JP2003174183A | ||||
| JP2000077698A | ||||
| JP2001701U |
| US20080047605 |
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