Research On The Design Method And Optimization Method Of Freeform Illumination

Illumination problem is one of the two major problems in nonimaging optics, with another the solar energy collection problem. Compared with the conventional surface illumination, freeform surface illumination have more flexible spatial layout and higher degrees of design freedom. This paper focuses on studying the design methods of freeform surface illumination and optimization methods, aiming to establish an effective theory for designing smooth freeform surface, and provide a set of reliable solutions for the freeform surface illumination. This paper first summarizes the main present design methods, and points out some insufficiencies in these methods. And a set of effective methods are proposed for design smooth freeform illumination by combining the advantages of these methods. According to different light source, the design methods of freeform surface illumination can be divided into freeform surface design method for point source of light and freeform surface design methods for extended light source. At present, the freeform surface design methods for point source of light mainly includes the free-form surface design method based on differential equation, the divided mesh method and the SP method. Because of the narrow scope of the free-form surface design method based on differential equation, the difficulty to obtain a continuous freeform surface with the divided mesh method, the difficulty to obtain a continuous freeform surface with the SP method, this paper proposes a hybrid design method, which combines the advantages of these methods, and compensates for their drawbacks. Finally, a continuous and smooth freeform surface which can realize the prescribed illumination is obtained by this method. For light source with certain extension, the freeform surface design method for point source of light is difficult to realize the prescribed illumination. An optimization method to some extent, can eliminates this problem, but the most fundamental way to terminate this problem is to put forward a set of design methods of freeform surface illumination for extended light source. As a try, this paper introduces the methods of nonimaging optics used in solar energy collection into the illumination design, and a modified SMS method is proposed for illumination. In general, this paper makes two main tasks:fist, the present main freeform surface design methods of point source are summarized, and a hybrid method of freeform surface illumination is proposed; second, a modified SMS method used for illumination is proposed in this paper, making up for the freeform surface design methods for extended light source.