US3639251A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Liquid dye filters with narrow passbands
Assignee: United States Department of the Air Force
•
Filing: 1968-07-22
•
Granted: 1972-02-01
•
Expires: 1988-07-22
Abstract
Abstract Liquid dye filters for passing narrow spectral bands in astrophysical observations where combinations of various compounds in solution in methanol and acetone are used as dyes in thin layers between Pyrex glass plates to produce a homogeneous filter which selectively absorbs the major portion of the spectrum in and near visible light allowing only a narrow band in the lambda 3,000 to lambda 4,500 A. range to pass.
Inventors
- 👤 Karl Wurm
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-31 05:10
CPC Classifications
G; G02; G02B; G02B5/00; G02B5/20; G02B5/22; G02B5/24
Claims Analysis
Total Claims: 2
Claim 1
Independent Claim
33 words
The liquid dye filter defined in claim 1 wherein an amount of 1.2.3.6.7.8-hexahydro-pyrene is added to said solution in sufficient quantity such that the highest gradient of extinction occurs at lambda 3,350 A.
Claim 2
Dependent Claim
35 words
The liquid dye filter defined in claim 2 wherein an amount of trans-stilbene is added to the solution in sufficient quantity to cover the double minimum of extinction of the hexahydro-pyrene around lambda 3,250 A.
References Cited (Backward Citations)
US3370902A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1975-01-31 | 1975-08-02 | 1976-02-01 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1979-01-31 | 1979-08-02 | 1980-02-01 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1983-01-31 | 1983-08-02 | 1984-02-01 | $7700.00 | Window Closed / Lapsed |