Why is the LS-1-CAL curve not a true blackbody radiator?
Please note: The LS-1-CAL is no longer available. This FAQ is intended for existing LS-1-CAL users.
The LS-1-CAL is not meant to be a blackbody source. The light is transmitted through a Teflon diffuser that transmits light in all directions, preventing this source being used as a blackbody source.
Instead, the LS-1-CAL is designed to be a radiometric standard for absolute irradiance. The lamp used within the LS-1-CAL has a filament color temperature rated at 2800K. The lamp is then mounted in a reflector and transmitted through the Teflon diffuser. Therefore, the shape of the curve will be similar to a 2800K blackbody but will be “shifted,” usually to a lower color temperature.