正弦条件を満足するフレネルレンズ——高屈折率法から最適実形状を導く新しい設計手法——

摘要

We propose a method to design spherical Fresnel lenses of collecting sun light that generate no coma aberration in the vicinity of optical axis. Since conventional Fresnel lenses have been designed to have brazed surface relieves only on one side of the lens, the section point between the incident ray and outgoing ray does not locate on a sphere, the radius of which is equal to the focal length and the center of which is at the image-side focal point. Thus the sine condition is not satisfied and then coma aberration appears. To solve this problem, we consider Fresnel lens having brazed feature on both sides. We theoretically shows that the coma aberration is not generated. By practical lens designing, we demonstrate the validity of our theory. The proposed method is useful to decide the brazed feature of any Fresnel lens from the result of high refractive index method.