US5308552A
Expired / Lapsed
US
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Method of fabricating anisometric metal needles and birefringent suspension thereof in dielectric fluid
Assignee: The AT&T MVPD Group LLC
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Filing: 1992-07-10
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Granted: 1994-05-03
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Expires: 2012-07-10
Abstract
Abstract A grating (22) of narrow parallel ridges (24) is formed in the surface (26) of a substrate (20) made of a hard material such as silicon dioxide. Metal (40) is deposited onto the grating (22) perpendicular to the ridges (24) at an angle of approximately 45° to the surface (26) of the grating such that the metal (40) is deposited onto the top (24a) and one of the sides (24b) of the each of the ridges (24) to form generally L-shaped metal strips (12') thereon. The metal strips (12') are cut at periodic intervals along the ridges (24) to produce anisometric metal needles (12). The substrate (20) is immersed in a dielectric fluid (14), and ultrasonic energy is applied to cause the needles (12) to release from the substrate (20) into suspension in the fluid (14). The L-shape of the needles (12) makes them resistant to bending. The suspension ( 10) has birefringent properties similar to liquid crystals, but may be electrically switched at much higher speed. The index of refraction of the suspension (10) varies in accordance with the alignment of the needles (12), thereby enabling the direction and phase of an electromagnetic wave propagating through the suspension (1) to be controlled by varying the magnitude of the applied electric field.
Inventors
- 👤 Chan S. Bak
- 👤 Leroy J. Miller
- 👤 Camille I. Van Ast
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 22:37
CPC Classifications
C; C23; C23C; C23C14/00; C23C14/22; C23C14/225; C23C14/0005; C23C14/04; G; G02; G02F; G02F1/00; G02F1/01; G02F1/17; G02F1/172; Y; Y10; Y10T; Y10T428/00; Y10T428/12; Y10T428/12014; Y10T428/12021; Y10T428/12424; Y10T428/12431; Y10T428/12438; Y10T428/12458; Y10T428/12465; Y10T428/12493
Claims Analysis
Total Claims: 15
Claim 1
Independent Claim
68 words
A birefringent fluid suspension system, comprising: a dielectric fluid; and a plurality of electrically conductive anisometric metal needles suspended in said dielectric fluid, each needle having a generally L-shaped cross-section, a length of between approximately 5,000-40,000 Angstroms, a width and a height each of between approximately 500-10,000 Angstroms, and a thickness of between approximately 200-3,000 Angstroms; the metal needles constituting between approximately 0.01%-10% of the suspension by volume.
Claim 2
Dependent Claim
68 words
A birefringent fluid suspension system, comprising: a dielectric fluid; and a plurality of electrically conductive anisometric metal needles suspended in said dielectric fluid, each needle having a generally L-shaped cross-section, a length of between approximately 5,000-40,000 Angstroms, a width and a height each of between approximately 500-10,000 Angstroms, and a thickness of between approximately 200-3,000 Angstroms; the metal needles constituting between approximately 0.01%-10% of the suspension by volume.
Claim 3
Dependent Claim
34 words
A suspension as in claim 1, in which the dielectric fluid comprises a material selected from the group consisting of ketones, alcohols, esters, aliphatic and aromatic hydrocarbons, aliphatic and aromatic halocarbons, aldehydes, and amines.
Claim 4
Dependent Claim
20 words
A suspension as in claim 1, in which the dielectric fluid comprises an organic material having substantially no permanent dipole.
Claim 5
Dependent Claim
30 words
A suspension as in claim 3, in which the organic material comprises a material selected from the group consisting of aliphatic hydrocarbons, aliphatic perfluorocarbons, and symmetrically substituted organic molecular materials.
Claim 6
Dependent Claim
36 words
A suspension as in claim 1, in which the dielectric fluid comprises an aliphatic hydrocarbon selected from the group consisting of pentane, hexane, heptane, octane, nonane, decane, undecane, dodecane, tridecane, tetradecane, pentadecane, hexadecane, and isomers thereof.
Claim 7
Dependent Claim
24 words
A suspension as in claim 1, in which the dielectric fluid comprises a cycloaliphatic hydrocarbon selected from the group consisting of cyclohexane and decalin.
Claim 8
Dependent Claim
27 words
A suspension as in claim 1, in which the dielectric fluid comprises a symmetrical aromatic hydrocarbon selected from the group consisting of benzene, paraxylene, mesitylene, and 1,3,5-triethylbenzene.
Claim 9
Dependent Claim
14 words
A suspension as in claim 1, in which the dielectric fluid comprises carbon tetrachloride.
Claim 10
Dependent Claim
32 words
A suspension as in claim 1, further comprising a solid organic material in solution with the dielectric fluid, the solid organic material having a symmetrical chemical structure and substantially no permanent dipole.
Claim 11
Dependent Claim
27 words
A suspension as in claim 9, in which the solid organic material is selected from the group consisting of carbon tetrabromide, para-dichlorobenzene, 1,3,5-trichlorobenzene, 1,2,4,5-tetrachlorobenzene, 1,3,5-tribromobenzene, and 1,2,4,5-tetrabromobenzene.
Claim 12
Dependent Claim
24 words
A suspension as in claim 1, in which the dielectric fluid comprises a material selected from the group consisting of bromoform, 1,1,2,2-tetrabromoethane, and 1,1,1,2-tetrabromoethane.
Claim 13
Dependent Claim
50 words
A suspension as in claim 1, in which each metal needle comprises: a first metal layer having said generally L-shaped cross section which includes an inwardly facing concave surface and an outwardly facing convex surface; and a second metal layer formed on said convex surface of the first metal layer.
Claim 14
Dependent Claim
21 words
A suspension as in claim 12, in which the first metal layer comprises copper, and the second metal layer comprises aluminum.
Claim 15
Dependent Claim
33 words
A suspension as in claim 13, in which the first metal layer has a thickness of between approximately 10-100 Angstroms, and the second metal layer has a thickness of between approximately 100-3,000 Angstroms.
References Cited (Backward Citations)
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