DESIGN CONSIDERATIONS FOR TWO-DIMENSIONAL SYMMETRIC BOOTLACE LENSES.
NAVAL RESEARCH LAB WASHINGTON D C
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It is well known that the two-dimensional symmetric bootlace lens, commonly referred to as the R-2R lens, has the property that perfect focusing can be achieved for infinitely many positions of the point source. This report shows that it is the only such lens having this property indeed, that it is the only one for which perfect focusing can be achieved for three or more pairs of focal points not on the axis of the lens. In the course of this demonstration, equations were obtained for the lens contours determined by two pairs of off-axis focal points. It was seen that the directions of the emerging beam could be different from those of the focal radii of the sources, provided the constraint given was satisfied. Finally, it was also shown that infinitely many lenses are possible for which a pair of conjugate off-axis focal points and a single on-axis focal point are prescribed. Author