This paper presents a segment and spline synthesis optimization method (SSS method) for the freeform total-internal-reflection (TIR) lens design. Before the optimization starts, a series of discrete control points are used to describe the TIR lens profile. In order to realize initial optimization, the segment method is applied to optimize a linear-segmented TIR lens. The final optimization is further achieved by the spline optimization method, after which the cubic-spline-modeling TIR lens with the characteristic of low cost and easy fabrication could satisfy the target illumination requirements. The detailed design principle and optimization process of the SSS method are both analyzed and compared in the paper. Complementing each other, the synthesis of the segment and spline optimization method could realize the prescribed design and greatly improve the design efficiency for designers. As an example, the specially designed polymethyl methacrylate (PMMA) freeform TIR lens used for LED general lighting could demonstrate the effectiveness of this method. The uniformity of the lens significantly increases from 67% to 88% after the segment and spline method, respectively. High light output efficiency (LOE) of 99.3% is available within the target illumination area for the final lens system. It is believed that the SSS method could be applied to design other freeform illumination optics.

Date Published: 15 October 2012
PDF: 8 pages
Proc. SPIE 8420, 6th International Symposium on Advanced Optical Manufacturing and Testing Technologies: Optical System Technologies for Manufacturing and Testing, 84200T (15 October 2012); doi: 10.1117/12.973665

Published in SPIE Proceedings Vol. 8420:
6th International Symposium on Advanced Optical Manufacturing and Testing Technologies: Optical System Technologies for Manufacturing and Testing
Xiangdi Lin; Yoshiharu Namba; Tingwen Xing, Editor(s)