A lens is said to have a pitch of 1.0 if its length is such that a ray completes one sinusoidal period in traveling through the lens. This is analogous to a series of four thin lenses spaced two focal lengths apart from one another to form an 8 focal length long telecentric relay. Quarter pitch GRIN lenses, with an object placed near the entrance face behave much like single thin lenses positioned one focal length away from the object.

Gradient index micro lenses (GRIN lenses) have a radially varying index of refraction that causes an optical ray to follow a sinusoidal propagation path through the lens. GRIN lenses have extremely low aberrations for objects near the optical axis, making them excellent for collimating diode lasers or coupling light into multimode optical fibers.

The general purpose plano-plano lenses are available in four wavelength options (630, 830, 1300, and 1560 nm). Each lens is cut to the pitch length for the specified wavelength, then coated with an appropriate antireflection coating.