Fiber-optic collimators are used to launch the light from an optical fiber into a free space collimated beam with specified beam diameter or spot size. In essence, a simple collimation lens is all that is needed for this. Thorlabs offers a variety of fiber collimation and coupling solutions. The beam's performance is governed by two primary parameters: 1) Beam Divergence. By utilizing diffraction limited lenses, the spot size of a few microns can be achieved.