"Achromatic limits" of Pancharatnam phase lenses.

Lenses based on the Pancharatnam phase have the advantage of being thin and inexpensive. Unfortunately, their optical effect is strongly wavelength dependent, and their applications generally are limited by the requirement of a monochromatic source. However, low-power lenses based on the Pancharatnam phase can be considered for applications over the visible range. In this paper, we provide intuitive "limits" for the lens power, below which these devices can be considered for use with the eye and visible light imaging applications.