skip to main content
DOE Patents title logo U.S. Department of Energy
Office of Scientific and Technical Information

Title: Systems for controlling the intensity variations in a laser beam and for frequency conversion thereof

Abstract

In order to control the intensity of a laser beam so that its intensity varies uniformly and provides uniform illumination of a target, such as a laser fusion target, a broad bandwidth laser pulse is spectrally dispersed spatially so that the frequency components thereof are spread apart. A disperser (grating) provides an output beam which varies spatially in wavelength in at least one direction transverse to the direction of propagation of the beam. Temporal spread (time delay) across the beam is corrected by using a phase delay device (a time delay compensation echelon). The dispersed beam may be amplified with laser amplifiers and frequency converted (doubled, tripled or quadrupled in frequency) with nonlinear optical elements (birefringent crystals). The spectral variation across the beam is compensated by varying the angle of incidence on one of the crystals with respect to the crystal optical axis utilizing a lens which diverges the beam. Another lens after the frequency converter may be used to recollimate the beam. The frequency converted beam is recombined so that portions of different frequency interfere and, unlike interference between waves of the same wavelength, there results an intensity pattern with rapid temoral oscillations which average out rapidly in timemore » thereby producing uniform illumination on target. A distributed phase plate (also known as a random phase mask), through which the spectrally dispersed beam is passed and then focused on a target, is used to provide the interference pattern which becomes nearly modulation free and uniform in intensity in the direction of the spectral variation.« less

Inventors:
 [1];  [1];  [2]
  1. (Rochester, NY)
  2. (Pittsford, NY)
Issue Date:
Research Org.:
Rochester Univ., NY (USA)
Sponsoring Org.:
USDOE
OSTI Identifier:
867546
Patent Number(s):
4961195
Assignee:
University of Rochester (Rochester, NY) OAK
DOE Contract Number:  
FC08-85DP40200
Resource Type:
Patent
Country of Publication:
United States
Language:
English
Subject:
systems; controlling; intensity; variations; laser; beam; frequency; conversion; control; varies; uniformly; provides; uniform; illumination; target; fusion; broad; bandwidth; pulse; spectrally; dispersed; spatially; components; spread; apart; disperser; grating; output; wavelength; direction; transverse; propagation; temporal; time; delay; corrected; phase; device; compensation; echelon; amplified; amplifiers; converted; doubled; tripled; quadrupled; nonlinear; optical; elements; birefringent; crystals; spectral; variation; compensated; varying; angle; incidence; respect; crystal; axis; utilizing; lens; diverges; converter; recollimate; recombined; portions; interfere; unlike; interference; waves; results; pattern; rapid; temoral; oscillations; average; rapidly; producing; distributed; plate; random; mask; passed; focused; provide; nearly; modulation; free; provides uniform; frequency conversion; phase delay; frequency components; intensity variations; interference pattern; optical axis; time delay; optical element; optical elements; output beam; laser pulse; laser beam; laser amplifier; nonlinear optical; laser fusion; broad band; broad bandwidth; phase plate; fusion target; uniform illumination; producing uniform; delay device; direction transverse; distributed phase; intensity varies; frequency component; bandwidth laser; laser amplifiers; nonlinear optic; frequency converter; intensity pattern; /372/359/

Citation Formats

Skupsky, Stanley, Craxton, R. Stephen, and Soures, John. Systems for controlling the intensity variations in a laser beam and for frequency conversion thereof. United States: N. p., 1990. Web.
Skupsky, Stanley, Craxton, R. Stephen, & Soures, John. Systems for controlling the intensity variations in a laser beam and for frequency conversion thereof. United States.
Skupsky, Stanley, Craxton, R. Stephen, and Soures, John. Mon . "Systems for controlling the intensity variations in a laser beam and for frequency conversion thereof". United States. https://www.osti.gov/servlets/purl/867546.
@article{osti_867546,
title = {Systems for controlling the intensity variations in a laser beam and for frequency conversion thereof},
author = {Skupsky, Stanley and Craxton, R. Stephen and Soures, John},
abstractNote = {In order to control the intensity of a laser beam so that its intensity varies uniformly and provides uniform illumination of a target, such as a laser fusion target, a broad bandwidth laser pulse is spectrally dispersed spatially so that the frequency components thereof are spread apart. A disperser (grating) provides an output beam which varies spatially in wavelength in at least one direction transverse to the direction of propagation of the beam. Temporal spread (time delay) across the beam is corrected by using a phase delay device (a time delay compensation echelon). The dispersed beam may be amplified with laser amplifiers and frequency converted (doubled, tripled or quadrupled in frequency) with nonlinear optical elements (birefringent crystals). The spectral variation across the beam is compensated by varying the angle of incidence on one of the crystals with respect to the crystal optical axis utilizing a lens which diverges the beam. Another lens after the frequency converter may be used to recollimate the beam. The frequency converted beam is recombined so that portions of different frequency interfere and, unlike interference between waves of the same wavelength, there results an intensity pattern with rapid temoral oscillations which average out rapidly in time thereby producing uniform illumination on target. A distributed phase plate (also known as a random phase mask), through which the spectrally dispersed beam is passed and then focused on a target, is used to provide the interference pattern which becomes nearly modulation free and uniform in intensity in the direction of the spectral variation.},
doi = {},
journal = {},
number = ,
volume = ,
place = {United States},
year = {1990},
month = {1}
}

Patent:

Save / Share: