A wideband, e.g., 550 nm to 940 nm, apochromatic lens system for use with
an external aperture stop, includes first, second, and third optical
groups having, in order, positive, negative, and positive powers. The
first group includes four optical elements having, in order, negative,
positive, negative, and positive powers. The second group includes one
element of negative power; and the third group includes two elements each
having positive power. In another embodiment for use with an internal
stop, the system includes first, second, and third optical groups having,
in order, positive, positive, and negative powers. The first group
includes four optical elements having, in order, positive, negative,
positive, and negative powers. The second group includes one element of
positive power, and the third group includes one element of negative
power. In either embodiment, all of the optical elements are formed from
not more than three different types of glass material.