Claims
- 1. A solar blind optical filter comprising a carrier material containing a salt of a dithioic acid of the formula RCS.sub.2.sup.- X.sup.+, wherein R is an organic substituent that does not absorb ultraviolet light at wavelengths between 260 nanometers and 300 nanometers and X is a counterion.
- 2. The solar blind optical filter of claim 1 wherein R is alkyl or substituted alkyl.
- 3. The solar blind optical filter of claim 2 wherein R contains one to four carbon atoms.
- 4. The solar blind optical filter of claim 3 wherein R is isopropyl.
- 5. The solar blind optical filter of claim 1 wherein said counterion is selected from the group consisting of Na, N(C.sub.2 H.sub.5).sub.4 and C.sub.5 H.sub.10 NH.sub.2.
- 6. The solar blind optical filter of claim 1 wherein said carrier material is selected from the group consisting of water, solvent, polymeric film and solid media.
- 7. The solar blind optical filter of claim 6 wherein said polymeric film is polyvinylalcohol.
- 8. The solar blind optical filter of claim 7 wherein R is isopropyl.
- 9. The solar blind optical filter of claim 8 wherein said counterion is NR.sub.4.sup.+ where R is an organic substituent that does not absorb light between wavelengths of 260 nm and 300 nm.
- 10. The solar blind optical filter of claim 9 wherein said counterion is N(C.sub.2 H.sub.5).sub.4.
- 11. The solar blind optical filter of claim 10 wherein said salt of a dithioic acid is (CH.sub.3).sub.2 CHCS.sub.2.sup.- N(C.sub.2 H.sub.5).sub.4.sup.+.
- 12. The solar blind optical filter of claim 6 wherein said solvent is ethanol, ethylene glycol or combinations thereof.
- 13. The solar blind optical filter of claim 6 wherein said solid media is glass, alumina or silica microspheres.
- 14. The solar blind optical filter of claim 1 wherein said salt of a dithioic acid is present in said carrier material at a concentration of between about 0.5% and 10% based on weight.
- 15. The solar blind optical filter of claim 14 wherein said salt of a dithioic acid is present in said carrier material at a concentration of about 5% by weight.
- 16. A solar blind optical filter which absorbs solar UV radiation and transmits non-solar UV radiation comprising a carrier material and a salt of a dithioic acid said salt of a dithioic acid being of the formula RCS.sub.2.sup.-X.sup.+ wherein R is any moiety that does not absorb UV radiation between about 260 nm and 300 nm and X is a counterion.
- 17. A solar blind optical filter which absorbs solar UV radiation and transmits non-solar UV radiation comprising:
- a carrier material selected from the group consisting of water, solvent, polymeric film and solid media; and
- a salt of a dithioic acid of the formula RCS.sub.2.sup.-X.sup.+, wherein R is alkyl or substituted alkyl containing one to four carbon atoms, and X is a counterion selected from the group consisting of Na, N(C.sub.2 H.sub.5).sub.4 and C.sub.5 H.sub.10 NH.sub.2.
- 18. The solar blind optical filter of claim 17 wherein said salt of a dithioic acid is (CH.sub.3).sub.2 CHCS.sub.2.sup.- N(C.sub.2 H.sub.5).sub.4.sup.+.
- 19. The solar blind optical filter of claim 17 wherein said filter has the following transmission characteristics: the transmission (T)
- is less than 0.005% at 345 nm, and
- is at least 90% between 270 nm and 300 nm.
- 20. A method for filtering solar radiation from a combination of solar and non-solar radiation sources, comprising the steps of:
- (a) providing a solar blind optical filter including a carrier material containing a salt of a dithioic acid of the formula RCS.sub.2.sup.- X.sup.+, wherein R is an organic substituient that does not absorb ultraviolet light at wavelengths between 260 nanometers and 300 nanometers and X is a counterion; and
- (b) positioning the solar blind optical filter in the path of the solar and non-solar radiation sources.
CROSS-REFERENCE TO RELATED APPLICATION
This application claims priority from U.S. Provisional Patent Application No. 60/092,925, filed Jul 15, 1998.
US Referenced Citations (10)