Cylinder lenses are similar to spherical lenses in the sense that they use curved surfaces to converge or diverge light, but they have optical power in only one dimension and will not affect light in the perpendicular dimension. This is impossible to accomplish using spherical lenses as light will focus or diverge uniformly in a rotationally symmetric manner. Cylinder lenses play an important role in the manipulation and shaping of laser light and are used for forming laser light sheets and circularizing elliptical beams. Due to the asymmetric nature of cylinder lenses and the specialized manufacturing processes required, it is important that the centration, wedge, and axial twist are specified and properly controlled.