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US4350413A
Expired / Lapsed
US
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Multi-color tunable filter
Assignee: United States Department of the Navy
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Filing: 1980-04-14
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Granted: 1982-09-21
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Expires: 2000-04-14
Abstract
Abstract A semi-conductor multi-color tunable filter is created by multiple epitaxial layers of varying composition. An AC modulation voltage is superimposed on a sweep bias to periodically shift the fundamental absorption edge of each individual epitaxial layer. This arrangement permits a unique voltage to be associated with a particular color. A lock-in filter matches colors observed at a detector with the voltage present for a given observation.
Inventors
- 👤 Nicholas Bottka
- 👤 Howard Lessoff
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 21:26
CPC Classifications
G; G02; G02F; G02F1/00; G02F1/01; G02F1/015
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
141 words
A multi-color tunable filter for light comprising: a substrate in the path of light for transmitting said light; a plurality of epitaxial layers on said substrate, placed such that said light passes through said plurality of epitaxial layers after passing through said substrate, for filtering selected wavelengths; means for producing a variable voltage potential across said substrate and epitaxial layers in a predetermined manner; a detector placed to intercept said light after it has passed through said epitaxial layers for measuring the amount of light that has passed through said substrate and epitaxial layers; a lock-in set to the predetermined manner in which said voltage varies and electrically connected to said detector for extracting a particular color signal as a function of the change in the output of said detector; and means for displaying the actual colors present in said light.
Claim 2
Dependent Claim
141 words
A multi-color tunable filter for light comprising: a substrate in the path of light for transmitting said light; a plurality of epitaxial layers on said substrate, placed such that said light passes through said plurality of epitaxial layers after passing through said substrate, for filtering selected wavelengths; means for producing a variable voltage potential across said substrate and epitaxial layers in a predetermined manner; a detector placed to intercept said light after it has passed through said epitaxial layers for measuring the amount of light that has passed through said substrate and epitaxial layers; a lock-in set to the predetermined manner in which said voltage varies and electrically connected to said detector for extracting a particular color signal as a function of the change in the output of said detector; and means for displaying the actual colors present in said light.
Claim 3
Dependent Claim
84 words
A multi-color tunable filter for light as described in claim 1 wherein said voltage means comprises; electrical contacts placed on the unfiltered side of said substrate and on the outermost layer of said plurality of epitaxial layers; a variable voltage source electrically connected to said electrical contacts for depleting said epitaxial layers with a negative sweep bias that reaches a final voltage, -V o , that depletes across all epitaxial layers; and means for superimposing an AC modulation voltage on said negative sweep bias.
Claim 4
Dependent Claim
24 words
A multi-color tunable filter for light as described in claim 2 where said AC modulation means comprises a squarewave generator of predetermined frequency, f.
Claim 5
Dependent Claim
40 words
A multi-color tunable filter for light as described in either claim 2 or claim 3 where said electrical contacts comprise a platinum-gold Schottky contact on the epitaxial layer side and gold-germanium ohmic contacts on the substrate side of said filter.
Claim 6
Dependent Claim
18 words
A multi-color tunable filter for light as described in claim 1 where said substrate comprises N+ type GaAs.
Claim 7
Dependent Claim
48 words
A multi-color tunable filter for light as described in any of claims 1, 2, 3 or 5 wherein said plurality of epitaxial layers are comprised of N type GaAs 1-X Sb X , where X equals the mole fraction of GaSb normalized to the number of As atoms.
Claim 8
Dependent Claim
24 words
A multi-color tunable filter for light as described in any of claims 1, 3 or 5 where said display means is a cathode-ray tube.
References Cited (Backward Citations)
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1985-09-20 | 1986-03-22 | 1986-09-21 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1989-09-20 | 1990-03-22 | 1990-09-21 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1993-09-20 | 1994-03-22 | 1994-09-21 | $7700.00 | Window Closed / Lapsed |