This package contains transmission spectra for different types of
optical filters and filter-like objects. These spectral data are NOT
normalized. In most cases they have been obtained from sheets of the
standard thickness supplied by sellers. Metadata is stored together with
the spectral data, when available, it includes thickness, an approximate
estimate of Rfr (contribution of reflectance) and whether
attenuation by the filter is based on reflection, absorption or both.
Beware that when attenuation is by absorption in the body of the filter,
thickness has a strong effect on the wavelengths at which Tfr = 0.5 is
reached for a given material. Be also aware that some of the data are for
total transmittance and some for internal transmittance. Depending on the
type of filter, spectral transmittance depends more or less strongly on the
angle of incidence of radiation. All measurements included have been done
with a angle of incidence that deviates at most by a 10 degrees from zero
(light beam perpendicular to the surface of the filter). Additional data is
provided in the documentation for different objects, and metadata is also
stored as attributes in the individual spectral objects. When metadata are
available, estimates of spectral transmittance for different thicknesses
can be approximately computed for filters based on ionic or absorptive
glass or plastic. The same is true for the conversion between total and
internal transmittance if Rfr is available. There are also filters
based on surface reflection or absorptive layers on the surface or encased.
Some filters even use a combination of these approaches.
Total spectral transmittance for climate screens used in agriculture and
horticulture is also included.
In addition to transmittance for semitransparent materials, the package
also contains data on the refractive index as a function of wavelength, for
several different materials. These data allow the estimation of spectral
reflectance for these materials.
Spectral reflectance data is included for several common metals and for
natural and man-made surfaces (relevant to remote sensing).
Transmittance data are included for:
The whole catalogue of Schott optical filters (official data
supplied by Schott for inclussion in this package).
Most of the catalogue of MIDOPT filters (official data
extracted from dowloaded files from supplier, reproduced with permission).
Clear glass as used in windows (as used by CIE, from data file
downloaded from CIE's server.)
Several types of Plexiglas from Evonik measured at our lab.
Other types of plastic sheets supplied by Foiltek Oy and Etola Oy,
measured at our lab.
Plastic films from McDermit and Courtaulds,
measured at our lab.
Several types of theatrical 'gels' from Lee, Rosco, and Formmatt.
Some measured at our lab and others data digitized from manufacturers'
catalogues.
Films used as greenhouse cladding from BPI Agri/Visqueen,
XL-horticulture and generic, measured at our lab.
Various filters used in UV, VIS and IR imaging and photography.
