A laser-sphere source for radiometric applications

摘要

An optical radiometric system based on a laser-illuminated integrating sphere, a pair of calibrated apertures and a calibrated silicon detector is described. The source comprises an integrating sphere with a direct-coupled 650 nm single-longitudinal-mode diode laser power stabilised to approx0.005 percent and wavelength stabilised to approx0.0006 nm. The effective areas of the apertures were measured to better than 0.005 percent using a macroscopic scanning probe technique. The responsivity of the 18 X 18 mm silicon detector was calibrated to better than 0.02 percent directly against a cryogenic radiometer. This system has applications in absolute radiometry and radiation thermometry. Overall, this system has uncertainties of < 0.04 percent. The system was used to replace the gold freezing point as a reference radiance source for radiation thermometry. Although its performance as a radiance reference is excellent, preliminary results in its application to radiation thermometry are presently limited by coherent interreflection within the pyrometer optics.