Guide to UV Measurement
Spectral Distribution
Spectral Distribution is the relative radiant energy as a function of wavelength or wavelength range. It is the wavelength distribution of radiant energy emitted by a source or arriving at a surface. It may be expressed in power units or in relative (normalized) terms.
All bulb manufacturers can provide the spectral out put of their lamps. However, the form of the data will vary from one manufacturer to another.
Original bulb emission data is collected by the use a monochromator. The resolution of a monochromator can be as fine as ½ nm, depending on the setting of the instrument. This results in a data display of the 200-450nm UV range of 500 data points! Further, because the plasma emission from a bulb consists of line (spike) emission and some continuous emission, this data is difficult to quantify for the purposes of UV curing. The actual amplitude of “spike” emission within the emission spectra is difficult to quantify, because it is very dependent on instrument setting and calibration.
Typical Spectral Emission Display of a
Medium-Pressure Mercury Vapor Lamp