A convex lens placed in front of the laser diode can converge the diverging light rays into a parallel beam. High-quality lenses with minimal aberrations are preferred to maintain the beam's. Cylindrical Lenses focus or expand light in one axis only. They can be used to focus light into a thin line in optical metrology, laser scanning, spectroscopic, laser diode, acousto-optic, and optical processor applications. They can also be used to expand the output of a laser diode into a. The elliptical beam emitted by the laser diode emits light, which can be used for applications, and lenses are used to shape and collimate it.