US4793709A
Expired / Lapsed
US
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Method and apparatus for measuring the losses of an optical cavity
Assignee: Northrop Grumman Guidance and Electronics Co Inc
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Filing: 1985-08-16
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Granted: 1988-12-27
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Expires: 2005-08-16
Abstract
Abstract A method and associated apparatus for measuring the intensity decay time of an optical cavity is particularly useful for accurate measurement of cavities of the type that include highly reflective mirrors. In the method, apparatus is provided for generating at least one pulse of laser light having a bandwidth that exceeds the resonant frequency spacing of the optical cavity and for directing that pulse into the cavity. The intensity of the light within the cavity is then measured and the amount of time is determined for such intensity to decay from a first predetermined value to a second predetermined value.
Inventors
- 👤 Salim N. Jabr
- 👤 Thomas M. Crawford
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 05:26
CPC Classifications
G; G01; G01M; G01M11/00; G01M11/005; G01N; G01N21/00; G01N21/17; G01N21/55; G01N21/21; G01N21/41; G01N2201/00; G01N2201/06; G01N2201/061; G01N2201/06113
Claims Analysis
Total Claims: 16
Claim 1
Independent Claim
107 words
Apparatus for measuring the intensity decay time of an optical cavity comprising, in combination: (a) a pump laser; (b) means responsive to said pump laser for producing a pulse of optical energy having a bandwidth that exceeds the resonant mode spacing of said cavity whereby multiple resonant modes of said cavity are simultaneously excited by said pulse; (c) means for injecting said pulse of optical energy into said cavity; (d) means for measuring the intensity of said injected optical energy within said cavity; and (e) means for measuring the amount of time for said intensity to decay from a first predetermined value to a second predetermined value.
Claim 2
Dependent Claim
107 words
Apparatus for measuring the intensity decay time of an optical cavity comprising, in combination: (a) a pump laser; (b) means responsive to said pump laser for producing a pulse of optical energy having a bandwidth that exceeds the resonant mode spacing of said cavity whereby multiple resonant modes of said cavity are simultaneously excited by said pulse; (c) means for injecting said pulse of optical energy into said cavity; (d) means for measuring the intensity of said injected optical energy within said cavity; and (e) means for measuring the amount of time for said intensity to decay from a first predetermined value to a second predetermined value.
Claim 3
Dependent Claim
33 words
Apparatus as defined in claim 1 further characterized in that said means for producing optical energy having a bandwidth that exceeds the resonant frequency spacing of said cavity is a tuneable dye laser.
Claim 4
Dependent Claim
23 words
Apparatus as defined in claim 2 further characterized in that at least one pulse of optical energy is between five and ten nanoseconds.
Claim 5
Dependent Claim
14 words
Apparatus as defined in claim 3 wherein said pump laser is a nitrogen laser.
Claim 6
Dependent Claim
14 words
Apparatus as defined in claim 3 wherein said pump laser is a Nd:YAG laser.
Claim 7
Dependent Claim
17 words
Apparatus as defined in claim 2 further including means for displaying the intensity of said optical energy.
Claim 8
Dependent Claim
42 words
Apparatus as defined in claim 6 wherein said means for measuring the intensity of said optical energy further includes: (a) means for producing an electrical signal responsive to said intensity; and (b) means for making a plurality of measurements of said signal.
Claim 9
Dependent Claim
25 words
Apparatus as defined in claim 7 wherein said means for producing an electrical signal is characterized by a response time of less than ten nanoseconds.
Claim 10
Dependent Claim
17 words
Apparatus as defined in claim 8 wherein said means for producing an electrical signal is a photodiode.
Claim 11
Dependent Claim
17 words
Apparatus as defined in claim 8 wherein said means for producing an electrical signal is a photomultiplier.
Claim 12
Independent Claim
90 words
A method for measuring the intensity decay time of an optical cavity comprising the steps of: (a) generating a pulse of laser light at a preselected wavelength having a bandwidth that exceeds the resonant mode spacing of said cavity; and (b) injecting said pulse into said cavity whereby multiple resonant modes of said cavity are simultaneously excited; then (c) measuring the intensity of laser light within said cavity; and (d) measuring the amount of time for said intensity to decay from a first predetermined level to a second predetermined level.
Claim 13
Independent Claim
90 words
A method for measuring the intensity decay time of an optical cavity comprising the steps of: (a) generating a pulse of laser light at a preselected wavelength having a bandwidth that exceeds the resonant mode spacing of said cavity; and (b) injecting said pulse into said cavity whereby multiple resonant modes of said cavity are simultaneously excited; then (c) measuring the intensity of laser light within said cavity; and (d) measuring the amount of time for said intensity to decay from a first predetermined level to a second predetermined level.
Claim 14
Dependent Claim
19 words
A method as defined in claim 11 wherein said second predetermined value is 1/e times said first determined value.
Claim 15
Independent Claim
54 words
A method of measuring losses in an optical cavity, comprising the steps of: (a) coupling a laser pulse into the cavity, the laser pulse having a plurality of longitudinal modes and exciting, in the cavity, multiple resonant modes; and (b) determining the time dependence of the decay of the laser pulse in the cavity.
Claim 16
Independent Claim
54 words
A method of measuring losses in an optical cavity, comprising the steps of: (a) coupling a laser pulse into the cavity, the laser pulse having a plurality of longitudinal modes and exciting, in the cavity, multiple resonant modes; and (b) determining the time dependence of the decay of the laser pulse in the cavity.
References Cited (Backward Citations)
US4571085A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
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| 3.5 Years (Year 4) | 1991-12-27 | 1992-06-27 | 1992-12-27 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1995-12-27 | 1996-06-27 | 1996-12-27 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1999-12-27 | 2000-06-27 | 2000-12-27 | $7700.00 | Window Closed / Lapsed |