Cylindrical lenses derive their name from their cylindrically contoured refracting surface, which is circular in shape when viewed in cross-section. Unlike spherically symmetrical lens elements, such as spherical singlets, cylindrical lenses allow light rays to converge (positive cylinders) or diverge (negative cylinders) in only one cross-section or meridian. Accordingly, the theory of performance for spherical singlets also applies to cylindrical singlets, but only along the axis with curvature or power. In fact, a cylindrical lens element may be abstractly considered as one-half of a spherical element; two crossed, mutually perpendicular cylinders of equal power behave in tandem as one spherical singlet.

Cylindrical lenses are either plano-convex (converging; positive focal length) or plano-concave (diverging; negative focal length) in form and rectangular in shape. Plano-convex cylindrical lenses, like their spherical counterparts, find applications as simple focusing optics and collimators in a single meridian. Similarly, plano-concave cylindrical lenses are used for beam expansion along a single axis. With cylindrical lenses, point sources can be imaged as lines, and vertical magnification can be different from horizontal magnification. Applications are especially numerous in imaging systems referred to as "anamorphic," a term which applies to the optics found in laser scanners, laser diode systems, spectrophotometers and projectors.

Our cylindrical lenses are available make of BK7 glass or fused silica. Plano-convex shapes produce lenses with positive focal lengths; plano-concave cylindrical lenses have negative focal lengths.