US3743380A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Polarized light source for underwater use
Assignee: United States Department of the Navy
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Filing: 1972-01-31
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Granted: 1973-07-03
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Expires: 1992-01-31
Abstract
Abstract A circularly polarized underwater light source comprising: a conventional unpolarized light source with a well-collimated output; an efficient optical polarizer, which employs multilayer interference polarization, total internal reflection, birefringent quarter-wave plates; and anti-reflection coatings; a lens to control the extent of the divergence of the illuminating beam; and an underwater housing with a dome-shaped window designed to withstand external hydrostatic pressures, part of the winding forming the lens.
Inventors
- 👤 R Fugitt
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-24 18:34
CPC Classifications
G; G02; G02B; G02B23/00; G02B23/16; G02B23/22; F; F21; F21L; F21L14/00; F21L14/02; F21S; F21S8/00; F21V; F21V9/00; F21V9/14; G02B27/00; G02B27/28; G02B27/283; F21W; F21W2131/00; F21W2131/40; F21W2131/401
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
340 words
A portable illuminating light source, comprising: a light polarizer which comprises: a pair of polarizing beam splitters, in the form of transparent parallel layers, each beam splitter making an acute angle with a vertical reference plane of symmetry such that unpolarized, incident light, parallel to the plane of symmetry, becomes polarized and is half reflected by each of the beam splitters, so that the plane of polarization of the reflected light is parallel to the plane of symmetry, and half transmitted through the beam splitter, with the plane of polarization perpendicular to the plane of symmetry; a pair of reflecting plates, each disposed substantially parallel to, and of substantially the same dimensions as, the beam splitters, having a totally internally reflecting surface on that one of its surfaces which is adjacent to the beam splitter, so that an incident beam on that surface is reflected parallel to the incident light; a first quarter-wave plate disposed perpendicularly to the plane of symmetry so as to intercept the light transmitted by the beam splitter, the fast axis of the plate making an angle of 45* with respect to the plane of polarization of the transmitted light; and second and third quarter-wave plates, disposed adjacent and parallel to the first quarter-wave plate, so as to intercept the light reflected by the reflecting plates, the fast axis of the second and third plates making an angle of 45* with respect to the plane of polarization of the reflected light; with the result that any light emerging from both quarter wave plates is circularly polarized light of the same handedness; a housing, for supporting the light polarizer; a handle, attached to the housing; a bracket, to which the light polarizer is attached, connected to the housing; a source of unpolarized light, aligned with the light polarizer, connectable to a source of electrical energy, and also attached to the bracket; and a window of transparent material, disposed flush against and attached to the housing, for passing the polarized light; the combination providing a circularly-polarized light source.
Claim 2
Dependent Claim
340 words
A portable illuminating light source, comprising: a light polarizer which comprises: a pair of polarizing beam splitters, in the form of transparent parallel layers, each beam splitter making an acute angle with a vertical reference plane of symmetry such that unpolarized, incident light, parallel to the plane of symmetry, becomes polarized and is half reflected by each of the beam splitters, so that the plane of polarization of the reflected light is parallel to the plane of symmetry, and half transmitted through the beam splitter, with the plane of polarization perpendicular to the plane of symmetry; a pair of reflecting plates, each disposed substantially parallel to, and of substantially the same dimensions as, the beam splitters, having a totally internally reflecting surface on that one of its surfaces which is adjacent to the beam splitter, so that an incident beam on that surface is reflected parallel to the incident light; a first quarter-wave plate disposed perpendicularly to the plane of symmetry so as to intercept the light transmitted by the beam splitter, the fast axis of the plate making an angle of 45* with respect to the plane of polarization of the transmitted light; and second and third quarter-wave plates, disposed adjacent and parallel to the first quarter-wave plate, so as to intercept the light reflected by the reflecting plates, the fast axis of the second and third plates making an angle of 45* with respect to the plane of polarization of the reflected light; with the result that any light emerging from both quarter wave plates is circularly polarized light of the same handedness; a housing, for supporting the light polarizer; a handle, attached to the housing; a bracket, to which the light polarizer is attached, connected to the housing; a source of unpolarized light, aligned with the light polarizer, connectable to a source of electrical energy, and also attached to the bracket; and a window of transparent material, disposed flush against and attached to the housing, for passing the polarized light; the combination providing a circularly-polarized light source.
Claim 3
Dependent Claim
40 words
The light source according to claim 1, wherein each of the beam splitters of the light polarizer comprises a multilayer material wherein each layer consists of a material having a different index of refraction from a layer adjacent to it.
Claim 4
Dependent Claim
39 words
The light source according to claim 2, wherein the multilayer material comprises a set of substrates, generally of a low refractive index, upon each of which is deposited a film of material, generally having a higher index of refraction.
Claim 5
Dependent Claim
33 words
The light source according to claim 3, wherein at least one of the layers of the multilayer material has an optical thickness equivalent to a quarter wavelength of the light incident upon it.
Claim 6
Dependent Claim
48 words
The light source according to claim 4, wherein all of the layers of the multilayer material have an optical thickness equivalent to a quarter wavelength of the light incident upon it; and wherein the angle that the beam splitter makes with the plane of symmetry is approximately 45*.
Claim 7
Dependent Claim
65 words
The light source according to claim 5, further comprising: a sheet of transparent material disposed perpendicularly to the plane of syMmetry adjacent to the beam splitters and the reflecting plates, on that side of the beam splitters and reflecting plates where the unpolarized light is incident; an anti-reflecting coating disposed on that surface of the sheet of transparent material where the impinging unpolarized light emerges.
Claim 8
Dependent Claim
61 words
The light source according to claim 6, further comprising: a second sheet of transparent material, disposed perpendicularly to the plane of symmetry adjacent to the quarter-wave plates, on that side of the quarter-wave plate where the circularly polarized light emerges; and a second anti-reflecting coating disposed on that surface of the sheet of transparent material where the circularly polarized light emerges.
Claim 9
Dependent Claim
74 words
The light source according to claim 7, further comprising: two prisms, each having a cross section in the shape of a parallelogram in a plane perpendicular to the plane of symmetry; one prism being disposed between the first-named anti-reflecting coating and second-named quarter-wave plate; the other prism being disposed between the first-named anti-reflecting coating and the third quarter-wave plate; and a triangular prism disposed between the two beam splitters and the first-named quarter-wave plate.
Claim 10
Dependent Claim
33 words
The circularly-polarized light source according to claim 8, wherein the window has a configuration such that light emitted by the light source is slightly divergent through at least a portion of the window.
Claim 11
Dependent Claim
40 words
The circularly-polarized light source according to claim 9, further comprising: a ring fitting snugly against and encircling the junction of the lens and housing so as to form a watertight connection, thereby making the light source suitable for underwater use.
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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) | 1976-07-02 | 1977-01-01 | 1977-07-03 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-07-02 | 1981-01-01 | 1981-07-03 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-07-02 | 1985-01-01 | 1985-07-03 | $7700.00 | Window Closed / Lapsed |