Low
damage threshold, can NOT be used on high power/energy
lasers.
Metallic
coatings make very broad bandwidth reflectors. Usually it
is best to protect the coatings with a durable dielectric
layer as they are very soft and susceptible to scratching.
The efficiency of metallic reflectors falls off at shorter
wavelengths but this may be enhanced by the application of
a multi-layer dielectric thin film stack. The table shows
the reflectance. of each of the metals without any protection
or enhancement. Protected metallic coatings have a dielectric
coating layer over the metallic layer to protect the coating
from being oxidized in the air or from scratched. For enhanced
metallic coatings, a stack of dielectric layers are added
on the metallic coating to increase reflectance for a particular
wavelength range.
We
provides metallic high reflective coatings by material of
Au, Ag and Al. These coatings are applied to where the consistent
high reflection in a wide spectral rang is necessary. Their
reflectivity are not higher than dielectrics HR coatings,
but their HR spectrum can over near-UV, visible and near-IR.
In order to prevent these metallic coatings from oxidization,
these coatings have been deposited on a layer of dielectrics
coating.
Reflectance
of Metallic Coating at Normal Incidence