LP390 filters are absorptive filters used to block ultraviolet (UV) light while allowing high (>90%) visible and near-IR light transmission. Most silicon camera sensors have some sensitivity in the UV spectrum. In some color cameras this light can typically be recorded as if it is blue light, resulting in an exaggerated bluish tint. These filters are well suited for color imaging applications as they absorb UV light and are precision ground and polished to exceptional flatness and parallelism. They are also frequently used as simple protective windows, shielding expensive camera lenses from inevitable contamination and scratching over time or, in more challenging environments, even breakage.