Fig. 3.

Intensity distributions for USB2000 spectrometers with different in-built diffraction gratings as compared to the XL-A. Vis Diffraction grating optimized for the Visible spectral range, high/low intensity, the iris opened maximally/minimally. With the iris maximally opened, the maximum intensity of the spectrometer (4,000 counts) is reached, and the spectrometer is maxed out at these wavelengths. UV Diffraction grating optimized for the UV range. With the iris maximally opened, about 70% of the available channels are saturated; these data are therefore not shown. Note that the flash lamp used in the MWL-AUC is different from the one of the XL-A. Due to the design of the spectral dispersion/detection system in the USB2000 spectrometers, the raw intensity spectra for the different spectrometers are a convoluted function of both the emission spectrum of the flash lamp and the preinstalled diffraction grating of the spectrometer itself