| 摘要 |
PURPOSE:To improve the utilization efficiency of a solar light by focusing the solar light by the first and the second lens systems which have been formed so that a focal distance satisfied a prescribed condition, and making it incident on a photoconductor, and setting its incident angle to <=NA of the photoconductor. CONSTITUTION:The titled system is provided with the second lens system containing a convex lens 2, which has been provided in the vicinity of a focal position of a Fresnel lens 1 of the first lens system, and also at a position being distant from its focal position. When a focal distance of its first lens system 1, and a composite focal distance of the first lens system 1 and the second lens system 2 are denoted as f1 and f12, respectively, f12<f1 is set so that a solar light which has been focused by the first lens system is further focused by the second lens system and led into a photoconductor 3. Next, an incident angle of the solar light which is led into the photoconductor 3 from the second lens system is set to <=NA of the photoconductor, and also a diameter of a solar image is set to <= a diameter of the photoconductor. In this way, the utilization efficiency of the solar light can be improved. |
