Figure 9From: Adding an extra condition: a general method to design double freeform-surface lens for LED uniform illumination(Color online) Double freeform-surface lens designed (Lens II) by providing the distribution of the deviation angle. The ratios of the first and the total deviation angles are (a) 0, (b) 0.25, (c) 0.33, (d) 0.50, (e) 0.66, (f) 0.70, (g) 0.75, (h) 0.80, and (k) 1.0.Back to article page