FIG. 6: Comparisons between the predicted (the “+” sign) and the actual (the “o” sign) positions of the images. The vertical axis is the source-lens distance measured from the source location to the center of the first layer of the holes. The horizontal axis is the position of the image. The results for the 9-layer and 13-layer structures are shown in the upper and lower subplots, respectively. The two vertical lines represent the boundaries of the lens. 15