Dichroic reflectors are the easiest step to take to reduce heat to your substrate. These reflectors can be specified for your Fusion UV curing system. Or, if you find your needs change, they can be easily retrofitted into an existing system.
Dichroic reflectors are exactly the same dimensions as a conventional reflector product, but they have 50 or more layers of a dielectric coating applied to their surface. This coating allows UV to be reflected, but absorbs much of the longer infrared (IR) wavelengths. The heat is then dissipated from the reflector surface by air-cooling.
More information on this technology can be found in the technical paper “Dichroic Reflectors Applied to High Peak Irradiance Microwave-powered UV Lamps", written by Dick Stowe.
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Typical spectral reflectance curve for a Fusion dichroic reflector.
There is little reflectance of visible or IR radiation. The total UV reflectivity can be very good for a well designed dichroic reflector. A comparison of the cure speed and surface temperature rise for a cure system with and without a dichroic reflector is shown in Table 5.
In this example, a significant reduction in peak temperature is accompanied by only a slight reduction in cure speed.
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