To provide an optical filter that approximates sunlight that is both durable and stable for long periods of time when subject to harsh light intensity, thermal and moisture loads of an accelerating weathering device.
In some embodiments, the filter is composed so that it has a thickness of 0.7 to 10 mm. In another embodiment, the optical filter is one part of an optical filter assembly suitable for manipulating spectral power distribution. The optical filter assembly includes a lead glass optical filter having a lead content of between 0.5 wt.% and 50 wt.% and an ultraviolet transmissive optical filter. In one embodiment, the ultraviolet transmissive optical filter is constructed from quartz glass. The ultraviolet transmissive optical filter can further include an infrared absorbing coating. In still another embodiment, an optical filter constructed from lead glass has a thickness selected such that the amount of illumination passing through the lead glass has a first ratio and a second ratio.
GUTH BRADLEY D
KETOLA WARREN D
RILEY JAMES W
Takashi Ishida
Tetsuji Koga
Nagasaka Tomoyasu
Yoshihiro Kobayashi
Atsushi Ebiya