Guide to UV Measurement
Lamps - Other Types
While medium-pressure mercury and mercury-plus-additive lamps are commonly used in UV Curing, several other types are available. These include low-pressure mercury Lamps, excimer lamps, LED sources, and Xenon “flash” lamps. Many of these are finding use in specialty applications. These are discussed only briefly here, as the measurement techniques and principles are generally the same.
Low-Pressure Mercury Lamps
Typically, these are called “germicidal lamps” because they emit strongly at the bio-kill wavelengths of 254 nm. They have less mercury in them than medium pressure mercury lamps, so tend to be monochromatic in their spectral distribution. view a chart of Low Pressure Mercury Lamp Spectral Distribution
Excimer Lamps
These are narrow-band emission lamps – essentially monochromatic sources at very specific wavelengths. The most often used types are centered at 308 nm and 172 nm.
LED Sources
These are constructed of arrays containing many LED (light-emitting-diode) solid-state “chips” and currently are limited to only UVA emission, longer than 380 nm. They are typically diffuse rather than focused sources. UV LED Lamps
Xenon “flash” Lamps
Lamps emitting high intensity pulses of broadband UV as they are driven with high voltage pulses. Promoted for their low infrared emission. For measurement, these lamps require specialized radiometers that will register short, high-irradiance pulses.