This application note describes the techniques that can be used
to compensate for the natural variation in output intensity of
miniature fluorescent bulbs. The output intensity for any 20nm
bandwidth can vary by as much as +50% from device to device.
A similar figure to LED output intensity tolerance. The major
factors, which cause this variation, are differences in the
phosphor coating from device to device and tolerances of the
anode and cathode geometries. External influences such as
ambient temperature will affect the output intensity. Before
discussing correction schemes the typical distribution of output
intensities is shown for a long wavelength ultra-violet miniature
fluorescent device. Similar distributions are obtained for other
spectral devices. The output intensities at 366nm of 50 lamps
were measured. The distribution is shown below.