Absolute calibration of a fluorescence collection system by Raman scattering in H_2

A new method for absolute calibration of the detection efficiency of fluorescence collection systems is described for wavelengths covering the 180–2000-nm range. The radiation source for the technique is spontaneous Raman scattering in H2. An analytic expression is derived for the scattering cross section averaged over the solid angle of the fluorescence collection system. From this result, an optical system is calibrated at 845 nm, demonstrating that the technique is easy to use, is quick to implement, and gives accurate results.