Geometric Feature of a Structure Composed of Concave and Convex Parabolic Mirrors

The convex side of a parabolic mirror realizes to convert focusing light into parallel one. Using this feature, we propose a structure which is composed of concave and convex parabolic mirrors. This new-type structure converts parallel light into highly-dense parallel light. The structure has several interesting geometric features. This structure realizes a conversion before passing a focal point. The structure offers the possibility of applications for industrial use. As one of the industrial applications, we suggest a daylighting system using this structure and we estimate its performance.