To achieve uniform illumination of a sample using optical fibers requires the use of collimating lenses, curved optical lenses that convert a divergent beam into a parallel beam. For this to occur, the light-emitting source must be placed at the focus of the lens. On the other hand, if the light collected is already collimated, the lens will work as a focusing lens. Sarspec has two different diameter lenses that are optimized for the UV-Vis-NIR range (up to 2500 nm) and allow users to adjust the field of view, control spatial resolution, and illumination/collection efficiency. Available in a smaller 6 mm and larger 12.7 mm diameter, our collecting lenses have a two-part anodized aluminum housing with an inner barrel threaded for SMA-905 connectors that helps you to adjust the focal point.