In UV curing processes, UV energy emitted by UV LED lamp is characterized by irradiance, energy density, spectral output, and spectral irradiance. Understanding these elements and how they are quantified enables users to better match UV curing sources to the needs of formulations, processes, and material handling.
Commonly referenced elements that characterize UV output include:
Irradiance (W/cm2) – This is the radiant power arriving at a cure surface from all forward angles, per unit area. It is typically reported as the effective irradiance over a defined bandwidth and is most meaningful when referenced to a specified working distance for the measured UV curing system.
Energy Density (J/cm2) – This is the radiant energy arriving at a cure surface per unit area. It is typically reported as the effective energy density over a defined bandwidth.
Spectral Output – This is the radiant output (W) of a lamp verses wavelength (nm). It is expressed in W/nm or W/10nm.
Spectral Irradiance – This is the radiant power of a lamp per unit area (W/cm2) verses wavelength (nm). In other words, it is the irradiance per wavelength. It is expressed in W/cm2/nm.
Irradiance, energy density, spectral output, and spectral irradiance vary by lamp type, lamp supplier, lamp head design, applied electrical power, and hours of operation. In addition, the magnitudes of the irradiance and energy density that ultimately reach the cure surface are heavily influenced by how systems are integrated into manufacturing lines and how well systems are maintained following commissioning. Fortunately, once a UV curing system is suitably matched to a formulation and properly integrated into a production line, the curing process is incredibly repeatable and can be held in control with periodic measurement of irradiance and energy density along with regular system maintenance.
Post time: Jun-23-2022