The front-end optics of a spectroradiometer includes the lenses, diffusers, and filters that modify the light as it first enters the system. For Radiance an optic with a narrow field of view is required. For total flux an integrating sphere is required. For Irradiance cosine correcting optics are required. The material used for these elements determines what type of light is capable of being measured. For example, to take UV measurements, quartz rather than glass lenses, optical fibers, Teflon diffusers, and barium sulphate coated integrating spheres are often used to ensure accurate UV measurement.