Thorlabs has introduced two fiber-coupled, broadband tungsten light sources (SLS201/SLS202), extending its broadband light sources product offering to spectroscopy for chemical, medical adn biological analysis. The sources come in two versions, both featuring a constant intensity blackbody radiation spectrum that ranges from either 300 to 2,600 nm (tungsten-halogen) or 450 to 5,500 nm (tungsten). The light sources have a built-in removable filter holder, allowing easy placement of standard Ø1” spectral filters into the light path. The internal feedback system of SLS201 and SLS202 stabilizes the light power variation to within 0.05% and reduces the power drift to 0.01% per hour compared to the standard 0.3% per hour typical of other tungsten-halogen light sources. This improvement allows the user to work for longer periods of time without needing to take another reference measurement.