Patent US3680965A successfully refreshed from Google Patents.
US3680965A
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Beamspread measurement camera for recording laser beam intensity distribution
Assignee: United States Department of the Army
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Filing: 1970-12-10
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Granted: 1972-08-01
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Expires: 1990-12-10
Abstract
Abstract Energy distribution within a laser beam is measured and a sample of the intensity is obtained, providing a self-calibrated photograph on a single film sample. A burst of laser energy striking a wedge plate or prism within the beamspread measurement camera is divided into multiple reflections within the prism. Each reflection is at a slightly greater angle than the preceeding one and is attenuated with respect thereto. Each reflection is collected by a lens and focused onto a spectrographic plate located at the lens focal point. The diameter of each image on the film is the product of the lens focal length and beamspread. The distribution pattern of each reflected sample is recorded on the same plate and can be compared with preceeding samples, each sample being a known percentage of the preceeding waves. Relative energy as a function of beamspread is determined by measuring the energy density of each image with a densitometer. Any point on each image of reflected energy is a known percentage of that point on the other images and provides a standard for determining the contour ring for a particular energy density on the initial spot, thus providing a contour map of the main beam.
Inventors
- 👤 James B Dilworth
- 👤 Thomas G Crow
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-29 23:27
CPC Classifications
G; G01; G01J; G01J1/00; G01J1/48; G01J1/42; G01J1/4257
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
82 words
Beamspread measurement apparatus for recording energy density of a laser beam comprising: a camera housing having an opening therein for directing a coaxially aligned incident laser beam therethrough, reflecting means within a first chamber of said housing and coaxially aligned with said opening for reflecting consecutive percentages of said laser beam, recording means within a second chamber of said housing, and a focusing lens within said housing for receiving said percentages of laser energy and directing said energy toward said recording means.
Claim 2
Dependent Claim
82 words
Beamspread measurement apparatus for recording energy density of a laser beam comprising: a camera housing having an opening therein for directing a coaxially aligned incident laser beam therethrough, reflecting means within a first chamber of said housing and coaxially aligned with said opening for reflecting consecutive percentages of said laser beam, recording means within a second chamber of said housing, and a focusing lens within said housing for receiving said percentages of laser energy and directing said energy toward said recording means.
Claim 3
Dependent Claim
58 words
Beamspread measurement apparatus as set forth in claim 1 wherein said reflecting means is a first prism having a reflective rear surface and a partially reflective front surface, said prism being positioned to allow multiple reflections of said laser beam therein with each reflection being at a slightly greater angle and attenuated with respect to a preceding reflection.
Claim 4
Dependent Claim
33 words
Beamspread measurement apparatus as set forth in claim 2 wherein said recording means is a spectrographic film at the focal point of said lens for recording an image of each reflection focused thereon.
Claim 5
Dependent Claim
58 words
Beamspread measurement apparatus as set forth in claim 3 and further comprising a mirror between said lens and said film for folding said laser beams into said second chamber, a calorimeter for measuring the power of said laser beam and a beam splitter adjacent said camera opening for directing a portion of said laser energy to said calorimeter.
Claim 6
Dependent Claim
61 words
Beamspread measurement apparatus as set forth in claim 4 wherein said reflecting means further comprises a plurality of prisms, each prism being adapted for replacing said first prism and having the separate and distinct combination of a partially reflective front surface and an angle of deflection for varying the percentage and position of respective laser beam reflections to said spectrographic film.
Claim 7
Independent Claim
141 words
A method for determining the relative energy of a laser beam as a function of beamspread comprising the steps of: a. directing a burst of incident laser energy toward a priSm, b. reflecting a decreasing percentage of said energy within said prism at successively increasing angles and simultaneously attenuating said reflected energy during each alternate reflection, c. deflecting a percentage of said incident wave and a percentage of each alternate reflection through a lens, d. focusing said deflected energy beams on a spectrographic plate and recording separate images for each deflected beam of the original incident beam, e. determining the maximum density of each recorded image and the gradient density of said incident deflected wave image, and f. indicating a contour ring of energy density on said incident deflected image corresponding to the maximum energy for each succeeding reflected wave image.
Claim 8
Independent Claim
141 words
A method for determining the relative energy of a laser beam as a function of beamspread comprising the steps of: a. directing a burst of incident laser energy toward a priSm, b. reflecting a decreasing percentage of said energy within said prism at successively increasing angles and simultaneously attenuating said reflected energy during each alternate reflection, c. deflecting a percentage of said incident wave and a percentage of each alternate reflection through a lens, d. focusing said deflected energy beams on a spectrographic plate and recording separate images for each deflected beam of the original incident beam, e. determining the maximum density of each recorded image and the gradient density of said incident deflected wave image, and f. indicating a contour ring of energy density on said incident deflected image corresponding to the maximum energy for each succeeding reflected wave image.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1975-08-01 | 1976-01-31 | 1976-08-01 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1979-08-01 | 1980-01-31 | 1980-08-01 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1983-08-01 | 1984-01-31 | 1984-08-01 | $7700.00 | Window Closed / Lapsed |