US5108185A
Expired / Lapsed
US
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Apparatus for measuring reflectivity
Assignee: Boston University
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Filing: 1989-06-12
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Granted: 1992-04-28
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Expires: 2009-06-12
Abstract
Abstract An apparatus for measuring the reflectivity of magnetooptic materials where the complex reflection coefficients of absorbing anisotropic media are determined. Amorphous rare-earth transition metal alloys exhibiting polar Kerr effect are analyzed for use as storage media in erasable optical storage systems.
Inventors
- 👤 Masud Mansuripur
- 👤 Michael Ruane
- 👤 Robert Rosenvold
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-03 06:48
CPC Classifications
G; G01; G01N; G01N21/00; G01N21/17; G01N21/21; G01N2021/218
Claims Analysis
Total Claims: 19
Claim 1
Independent Claim
78 words
A method of measuring reflectivity comprising: illuminating a magnetooptic material with polarized light having a selected orientation; reflecting the light from the surface of said material; measuring a first intensity of the light reflected by said material; applying a magnetic field to the magnetooptic material to produce a direction of magnetization in the material; measuring a second intensity of light reflected from the magnetized material; and determining a complex reflection coefficient from the first and second measured intensities.
Claim 2
Independent Claim
78 words
A method of measuring reflectivity comprising: illuminating a magnetooptic material with polarized light having a selected orientation; reflecting the light from the surface of said material; measuring a first intensity of the light reflected by said material; applying a magnetic field to the magnetooptic material to produce a direction of magnetization in the material; measuring a second intensity of light reflected from the magnetized material; and determining a complex reflection coefficient from the first and second measured intensities.
Claim 3
Dependent Claim
40 words
A method of measuring reflectivity as defined in claim 1 further comprising the steps of: reversing the direction of magnetization of the material; and measuring the intensity of the light reflected from the reversely magnetized material in two orthogonal planes.
Claim 4
Dependent Claim
56 words
A method of reflectivity as defined in claim 1 wherein said illuminating step is preceded by the steps of: forming a transparent protective layer on the magnetooptic material; and positioning a lens on said layer such that light normally incident upon said lens is essentially not reflected or refracted by the lens or the protective layer.
Claim 5
Dependent Claim
31 words
A method of measuring reflectivity as defined in claim 3 wherein film is placed between the lens and said protective layer having the same refractive index as said lens and layer.
Claim 6
Dependent Claim
37 words
A method of measuring reflectivity as defined in claim 3 further comprising the step of normalizing the measured intensity by measuring the intensity of light that is internally reflected by the lens without the layer and material.
Claim 7
Dependent Claim
23 words
A method of measuring reflectivity as defined in claim 1 wherein said magnetooptic material is illuminated from any of a multiplicity of angles.
Claim 8
Dependent Claim
26 words
A method of measuring reflectivity as defined in claim 1 wherein said illuminating step is preceded by the step of rotating the polarization of said light.
Claim 9
Dependent Claim
22 words
A method of measuring reflectivity as defined in claim 7 wherein said rotating step is comprised of rotating a polarizing beam splitter.
Claim 10
Dependent Claim
33 words
A method of measuring reflectivity as defined in claim 8 further comprising the step of normalizing the measured intensity by measuring variations in a polarized light source signal split by the beam splitter.
Claim 11
Dependent Claim
28 words
A method of measuring reflectivity as defined in claim 1 wherein said reflecting step is followed by the step of adjusting the phase delay of the reflected light.
Claim 12
Dependent Claim
27 words
A method of measuring reflectivity as defined in claim 1 wherein said reflecting step is followed by the step of rotating the polarization of the reflected light.
Claim 13
Dependent Claim
22 words
A method of measuring reflectivity as defined in claim 11 wherein said rotating step is comprised of rotating a polarizing beam splitter.
Claim 14
Dependent Claim
91 words
Apparatus for measuring reflectivity of magnetooptic material comprising: a polarized light source; a magnetooptic material illuminated by said source; a magnetic field source positioned adjacent the material to provide a selected direction of magnetization to the material; a moveable device to modify a phase difference between orthogonal components of light reflected by the material; and a detector system to measure the orthogonal components of reflected light by the material, the system having means to determine a complex reflection coefficient a complex reflection coefficient of the material from the measured orthogonal components.
Claim 15
Dependent Claim
91 words
Apparatus for measuring reflectivity of magnetooptic material comprising: a polarized light source; a magnetooptic material illuminated by said source; a magnetic field source positioned adjacent the material to provide a selected direction of magnetization to the material; a moveable device to modify a phase difference between orthogonal components of light reflected by the material; and a detector system to measure the orthogonal components of reflected light by the material, the system having means to determine a complex reflection coefficient a complex reflection coefficient of the material from the measured orthogonal components.
Claim 16
Dependent Claim
31 words
The apparatus of claim 13 further comprising a hemispheric lens positioned between the light source and the magnetooptic material to direct light from the source onto a surface of the material.
Claim 17
Dependent Claim
16 words
The apparatus of claim 14 wherein the lens and the surface are coupled by a film.
Claim 18
Independent Claim
91 words
A method of measuring reflectivity comprising: illuminating a magnetooptic material with polarized light having a selected orientation; reflecting the light from the surface of said material; measuring a first intensity of the light reflected by said material; applying a magnetic field to the magnetooptic material to produce a direction of magnetization in the material; modifying a phase difference between orthogonal components of light reflected by the material; measuring a second intensity of light reflected from the magnetized material; and determining a complex reflection coefficient from the first and second measured intensities.
Claim 19
Independent Claim
91 words
A method of measuring reflectivity comprising: illuminating a magnetooptic material with polarized light having a selected orientation; reflecting the light from the surface of said material; measuring a first intensity of the light reflected by said material; applying a magnetic field to the magnetooptic material to produce a direction of magnetization in the material; modifying a phase difference between orthogonal components of light reflected by the material; measuring a second intensity of light reflected from the magnetized material; and determining a complex reflection coefficient from the first and second measured intensities.
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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) | 1995-04-28 | 1995-10-28 | 1996-04-28 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1999-04-28 | 1999-10-28 | 2000-04-28 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2003-04-28 | 2003-10-28 | 2004-04-28 | $7700.00 | Window Closed / Lapsed |