Patent US4256378A successfully refreshed from Google Patents.
US4256378A
Expired / Lapsed
US
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Graphite-glass composite laser mirror
Assignee: RTX Corp
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Filing: 1979-07-02
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Granted: 1981-03-17
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Expires: 1999-07-02
Abstract
Abstract A laser mirror stable at high and low temperatures is described comprising graphite fibers in a glass matrix. The mirror is made by hot pressing a graphite fiber lay-up in a glass matrix in a die, the fibers laid up in such a way to produce a central plane of symmetry across the central plane of the composite. In use, the composite requires a separate laser reflecting surface layer. The resulting laser mirror has a low density but no porosity, high elastic stiffness, high strength, high fracture toughness, low thermal expansion, high thermal conductivity and environmental stability.
Inventors
- 👤 Karl M. Prewo
- 👤 Robert K. Stalcup
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 09:46
CPC Classifications
G; G02; G02B; G02B5/00; G02B5/08; C; C03; C03C; C03C14/00; C03C14/002; C03C2214/00; C03C2214/02; C03C2214/03
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
49 words
A laser mirror comprising a graphite fiberglass matrix composite having a graphite fiber lay-up in the glass matrix producing a symmetrical and balanced composite, containing 40%-70% volume graphite fibers, having an outer laser reflecting layer, and having a graphite fiber orientation in the composite of 0°/90°, 0°/45°/90° or 0°/60°.
Claim 2
Dependent Claim
49 words
A laser mirror comprising a graphite fiberglass matrix composite having a graphite fiber lay-up in the glass matrix producing a symmetrical and balanced composite, containing 40%-70% volume graphite fibers, having an outer laser reflecting layer, and having a graphite fiber orientation in the composite of 0°/90°, 0°/45°/90° or 0°/60°.
Claim 3
Dependent Claim
49 words
A laser mirror comprising a graphite fiber-glass matrix composite containing 40% to 70% by volume graphite fibers, having a laser radiation reflecting outer layer and having a graphite fiber lay-up in the glass matrix producing balance and a central plane of symmetry across the central plane of the composite.
Claim 4
Dependent Claim
49 words
A laser mirror comprising a graphite fiber-glass matrix composite containing 40% to 70% by volume graphite fibers, having a laser radiation reflecting outer layer and having a graphite fiber lay-up in the glass matrix producing balance and a central plane of symmetry across the central plane of the composite.
Claim 5
Dependent Claim
14 words
The mirror of claims 2 or 1 containing about 60% by volume graphite fiber.
Claim 6
Dependent Claim
12 words
The mirror of claims 2 or 1 wherein the glass comprises borosilicate.
Claim 7
Dependent Claim
38 words
The mirror of claims 2 or 1 wherein the graphite fiber has a modulus of elasticity of at least 531 GPa, a tensile strength of at least 1724 MPa and a density of about 1.96 gm/cm 3 .
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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) | 1984-03-16 | 1984-09-15 | 1985-03-17 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1988-03-16 | 1988-09-15 | 1989-03-17 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1992-03-16 | 1992-09-15 | 1993-03-17 | $7700.00 | Window Closed / Lapsed |