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| Spectral Output |
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Spectral output is defined as intensity of light at each wavelength over the range of wavelengths emitted by the lamp. For the most effective cure, this pattern of output must be matched to the pattern of absorption of the photoinitiator in the product. This principle forms the basis of all successful light cure applications. Spectral output determines whether a lamp is suitable for a particular application and how effectively the lamp will cure the product. Basic lamp engineering and modification of the material inside the lamp (called doping) enable shifting of emission maxima to other wavelengths to create different spectral output patterns.
Since there are certain absorption maxima common to many systems, there is often a choice of lamps for a given product. Major absorption areas of importance are 254 nm, responsible for surface cure, 365 nm, the "workhorse" cure wavelength also effective in promoting depth cure, and 400-436 nm in visible spectrum particularly useful for very large depth of cure. Please see the electromagnetic spectrum diagram,
figure A. |
