US3715164A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Four beam holographic interferometry
Assignee: Northrop Grumman Space and Mission Systems Corp
•
Filing: 1971-11-01
•
Granted: 1973-02-06
•
Expires: 1991-11-01
Abstract
Abstract A double-exposure holographic interferometric system for visualizing small disturbances of a subject. The system utilizes two reference beams and two subject beams cast simultaneously on a recording medium in such a way that the two subject beams and the two reference beams each form a small angle with each other. For the second exposure one of the subject beams and one of the reference beams is shifted in phase by 180* with respect to its associated beam. This will create a regular holographic grating which is phase modulated by the disturbances or perturbations of the subject. Upon proper reconstruction of the hologram the phase modulations will cause brightenings of the normally dark background of the reconstructed hologram. The system has the advantage that it is relatively insensitive to errors of phase shift or to variations of the light intensity between the two exposures.
Inventors
- 👤 L Heflinger
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-03 21:50
CPC Classifications
G; G01; G01N; G01N21/00; G01N21/17; G01N21/41; G01N21/45; G01N21/453; Y; Y10; Y10S; Y10S359/00; Y10S359/902
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
199 words
A double-exposure holographic interferometric system for visualizing small perturbations of a subject to be analyzed, said system comprising: a. a source of coherent monochromatic light; b. a recording medium; c. means for splitting the light from said source for the first exposure into a first subject beam and a first reference beam and into a second subject beam and a second reference beam and casting said beams onto said recording medium, said first and said second reference beams forming a small angle with each other at said recording medium, and said first and second subject beams forming a small angle with each other at said recording medium; and d. phase shifting means disposed into the path of at least one of said reference beams and one of said subject beams for the second exposure and for shifting the phase of one reference beam with respect to the other subsTantially by 180* and for shifting the phase of one subject beam with respect to the other substantially by 180*, whereby a subject may be interposed into the path of said subject beams and whereby perturbations of the subject will cause phase modulations of the grating recorded on said recording material.
Claim 2
Dependent Claim
199 words
A double-exposure holographic interferometric system for visualizing small perturbations of a subject to be analyzed, said system comprising: a. a source of coherent monochromatic light; b. a recording medium; c. means for splitting the light from said source for the first exposure into a first subject beam and a first reference beam and into a second subject beam and a second reference beam and casting said beams onto said recording medium, said first and said second reference beams forming a small angle with each other at said recording medium, and said first and second subject beams forming a small angle with each other at said recording medium; and d. phase shifting means disposed into the path of at least one of said reference beams and one of said subject beams for the second exposure and for shifting the phase of one reference beam with respect to the other subsTantially by 180* and for shifting the phase of one subject beam with respect to the other substantially by 180*, whereby a subject may be interposed into the path of said subject beams and whereby perturbations of the subject will cause phase modulations of the grating recorded on said recording material.
Claim 3
Dependent Claim
199 words
A double-exposure holographic interferometric system for visualizing small perturbations of a subject to be analyzed, said system comprising: a. a source of coherent monochromatic light; b. a recording medium; c. means for splitting the light from said source for the first exposure into a first subject beam and a first reference beam and into a second subject beam and a second reference beam and casting said beams onto said recording medium, said first and said second reference beams forming a small angle with each other at said recording medium, and said first and second subject beams forming a small angle with each other at said recording medium; and d. phase shifting means disposed into the path of at least one of said reference beams and one of said subject beams for the second exposure and for shifting the phase of one reference beam with respect to the other subsTantially by 180* and for shifting the phase of one subject beam with respect to the other substantially by 180*, whereby a subject may be interposed into the path of said subject beams and whereby perturbations of the subject will cause phase modulations of the grating recorded on said recording material.
Claim 4
Dependent Claim
199 words
A double-exposure holographic interferometric system for visualizing small perturbations of a subject to be analyzed, said system comprising: a. a source of coherent monochromatic light; b. a recording medium; c. means for splitting the light from said source for the first exposure into a first subject beam and a first reference beam and into a second subject beam and a second reference beam and casting said beams onto said recording medium, said first and said second reference beams forming a small angle with each other at said recording medium, and said first and second subject beams forming a small angle with each other at said recording medium; and d. phase shifting means disposed into the path of at least one of said reference beams and one of said subject beams for the second exposure and for shifting the phase of one reference beam with respect to the other subsTantially by 180* and for shifting the phase of one subject beam with respect to the other substantially by 180*, whereby a subject may be interposed into the path of said subject beams and whereby perturbations of the subject will cause phase modulations of the grating recorded on said recording material.
Claim 5
Dependent Claim
97 words
A holographic system as defined in claim 1 wherein said means for splitting the light from said source includes a first beam splitter for splitting the light from said source into a first and a second beam, a second beam splitter, reflector means for recombining said first and second beams at said second beam splitter, said beam splitter and said reflector means being so disposed as to recombine said first and second beams at a slight angle with respect to each other and said second beam splitter generating said two reference beams and said two subject beams.
Claim 6
Dependent Claim
38 words
A holographic system as defined in claim 2 wherein said phase shifting means consists of a 180* phase shifter disposed into the path of one of said first and second beams and ahead of said second beam splitter.
Claim 7
Independent Claim
228 words
The method of visualizing small perturbations of a subject to be analyzed by a double-exposed hologram consisting of a recording medium, said method comprising the steps of: a. generating a beam of coherent monochromatic light; b. splitting the monochromatic light into a first subject beam and a first reference beam and into a second subject beam and a second reference beam so that said first and second reference beams form a small angle with each other at the recording medium, and that said first and second subject beams form a small angle with each other at the recording medium; c. interposing a subject to be holographed into the path of said subject beams; d. exposing for the first time the recording medium with the two subject beams and with the two reference beams; e. interposing a perturbed subject into the path of the subject beams for a second exposure; f. shifting the phase of one of the two reference beams with respect to the other substantially by 180* and shifting the phase of one of the subject beams with respect to the other substantially by 180*; and g. exposing the recording medium to the two phase shifted reference beams and the two phase shifted subject beams through the perturbed subject, whereby the perturbations of the subject will cause phase modulations of the grating recorded on the recording medium.
Claim 8
Independent Claim
228 words
The method of visualizing small perturbations of a subject to be analyzed by a double-exposed hologram consisting of a recording medium, said method comprising the steps of: a. generating a beam of coherent monochromatic light; b. splitting the monochromatic light into a first subject beam and a first reference beam and into a second subject beam and a second reference beam so that said first and second reference beams form a small angle with each other at the recording medium, and that said first and second subject beams form a small angle with each other at the recording medium; c. interposing a subject to be holographed into the path of said subject beams; d. exposing for the first time the recording medium with the two subject beams and with the two reference beams; e. interposing a perturbed subject into the path of the subject beams for a second exposure; f. shifting the phase of one of the two reference beams with respect to the other substantially by 180* and shifting the phase of one of the subject beams with respect to the other substantially by 180*; and g. exposing the recording medium to the two phase shifted reference beams and the two phase shifted subject beams through the perturbed subject, whereby the perturbations of the subject will cause phase modulations of the grating recorded on the recording medium.
References Cited (Backward Citations)
US3619064A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1976-02-06 | 1976-08-07 | 1977-02-06 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-02-06 | 1980-08-07 | 1981-02-06 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-02-06 | 1984-08-07 | 1985-02-06 | $7700.00 | Window Closed / Lapsed |