US4196257A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Bi-alkali telluride photocathode
Assignee: RCA Corp
•
Filing: 1978-07-20
•
Granted: 1980-04-01
•
Expires: 1998-07-20
Abstract
Abstract A photocathode is formed by depositing a film of tellurium on a conductive base and then sensitizing the tellurium with at least two different alkali metals such as cesium and potassium or sodium and potassium. The photocathode has high sensitivity in the ultraviolet region and is substantially insensitive to solar radiation through the earth's atmosphere. Such a photocathode is useful in "solar-blind" detectors.
Inventors
- 👤 Ralph W. Engstrom
- 👤 Arthur F. McDonie
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-29 00:36
CPC Classifications
H; H01; H01J; H01J40/00; H01J40/02; H01J40/04; H01J40/06; H01J1/00; H01J1/02; H01J1/34; H01J2201/00; H01J2201/34; H01J2201/342; H01J2201/3421; H01J2201/3426; Y; Y10; Y10S; Y10S428/00; Y10S428/913; Y10T; Y10T428/00; Y10T428/31504; Y10T428/31678
Claims Analysis
Total Claims: 18
Claim 1
Independent Claim
57 words
In an electron emissive photocathode of the type having sensitivity to light in the ultra violet region and substantial insensitivity to light in the spectral region above 400 nanometers, said photocathode including a conductive base and a photoemissive surface on said base, the improvement wherein said photoemissive surface comprises tellurium and at least two different alkali metals.
Claim 2
Dependent Claim
57 words
In an electron emissive photocathode of the type having sensitivity to light in the ultra violet region and substantial insensitivity to light in the spectral region above 400 nanometers, said photocathode including a conductive base and a photoemissive surface on said base, the improvement wherein said photoemissive surface comprises tellurium and at least two different alkali metals.
Claim 3
Dependent Claim
41 words
A photocathode according to claim 1, wherein said alkali metals are selected from the group consisting of cesium, potassium and sodium that are reacted with said tellurium to form a photoemissive surface having negligible sensitivity to solar radiation through the atmosphere.
Claim 4
Dependent Claim
14 words
A photocathode according to claim 2, wherein said alkali metals are cesium and potassium.
Claim 5
Dependent Claim
28 words
A photocathode according to claim 3, wherein said tellurium, cesium and potassium are in substantially stoichiometric proportions according to the formula K x Cs 2-x Te, wherein 0<x<2.
Claim 6
Dependent Claim
14 words
A photocathode according to claim 2, wherein said alkali metals are sodium and potassium.
Claim 7
Dependent Claim
28 words
A photocathode according to claim 5, wherein said tellurium, sodium and potassium are in substantially stoichiometric proportions according to the formula Na x K 2-x Te, wherein 0<x<2.
Claim 8
Independent Claim
57 words
A method of making an electron emissive photocathode comprising the steps of depositing successively onto a conductive base tellurium and at least two different alkali metals that react with said tellurium to form a photoemissive surface having sensitivity to light in the ultra violet region and substantial insensitivity to light in the spectral region above 400 namometers.
Claim 9
Independent Claim
57 words
A method of making an electron emissive photocathode comprising the steps of depositing successively onto a conductive base tellurium and at least two different alkali metals that react with said tellurium to form a photoemissive surface having sensitivity to light in the ultra violet region and substantial insensitivity to light in the spectral region above 400 namometers.
Claim 10
Dependent Claim
35 words
A method according to claim 7, wherein said alkali metals are selected from the group consisting of cesium, potassium and sodium to form a photoemissive surface having negligible sensitivity to solar radiation through the atmosphere.
Claim 11
Dependent Claim
14 words
A method according to claim 8, wherein said alkali metals are cesium and potassium.
Claim 12
Dependent Claim
26 words
A method according to claim 9, wherein said cesium and potassium deposition is effected at a temperature range from about 140° C. to about 190° C.
Claim 13
Dependent Claim
28 words
A method according to claim 9 wherein said cesium and potassium are reacted stoichiometrically with said tellurium according to the formula K x Cs 2-x Te, wherein 0<x<2.
Claim 14
Dependent Claim
14 words
A method according to claim 8, wherein said alkali metals are sodium and potassium.
Claim 15
Dependent Claim
26 words
A method according to claim 12, wherein said sodium and potassium deposition is effected at a temperature range from about 160° C. to about 220° C.
Claim 16
Dependent Claim
28 words
A method according to claim 12, wherein said sodium and potassium are reacted stoichiometrically with said tellurium according to the formula Na x K 2-x Te, wherein 0<x<2.
Claim 17
Dependent Claim
24 words
A photocathode according to claim 7, wherein said tellurium is first deposited onto said base followed by successive depositions of said different alkali metals.
Claim 18
Dependent Claim
18 words
A photocathode according to claim 7, wherein one of said alkali metals is first deposited onto said base.
References Cited (Backward Citations)
US2668778A
Cited
US2770561A
Cited
US2868736A
Cited
US3006786A
Cited
US3020432A
Cited
US3434876A
Cited
US3902924A
Cited
US3867662A
Cited
US4098617A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1983-04-01 | 1983-10-01 | 1984-04-01 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1987-04-01 | 1987-10-01 | 1988-04-01 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1991-04-01 | 1991-10-01 | 1992-04-01 | $7700.00 | Window Closed / Lapsed |