A Fresnel freeform surface collimating lens for LEDs

摘要

This paper proposes a freeform surface lens design based on the Fresnel model to achieve a compact structure and good collimation. A simulation indicates the lens enjoys an efficiency as high as 88.43% within a half view angle of 2 for 1 × 1 mm~2 size LED. This paper makes a comparison of three types of lens, among which the Fresnel freeform lens achieves the best performance when the LED size is smaller than 2.5 × 2.5 mm~2. The influence of the LED size and the manufacturing tolerances are discussed.