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Title: Apparatus and method for laser beam diagnosis

Abstract

An apparatus and method are disclosed for accurate, real time monitoring of the wavefront curvature of a coherent laser beam. Knowing the curvature, it can be quickly determined whether the laser beam is collimated, or focusing (converging), or de-focusing (diverging). The apparatus includes a lateral interferometer for forming an interference pattern of the laser beam to be diagnosed. The interference pattern is imaged to a spatial light modulator (SLM), whose output is a coherent laser beam having an image of the interference pattern impressed on it. The SLM output is focused to obtain the far-field diffraction pattern. A video camera, such as CCD, monitors the far-field diffraction pattern, and provides an electrical output indicative of the shape of the far-field pattern. Specifically, the far-field pattern comprises a central lobe and side lobes, whose relative positions are indicative of the radius of curvature of the beam. The video camera's electrical output may be provided to a computer which analyzes the data to determine the wavefront curvature of the laser beam. 11 figures.

Inventors:
Publication Date:
OSTI Identifier:
7027459
Patent Number(s):
US 5042950; A
Application Number:
PPN: US 7-526757
Assignee:
Dept. of Energy, Washington, DC (United States)
DOE Contract Number:  
W-7405-ENG-48
Resource Type:
Patent
Resource Relation:
Patent File Date: 22 May 1990
Country of Publication:
United States
Language:
English
Subject:
42 ENGINEERING; LASER RADIATION; DIAGNOSTIC TECHNIQUES; BEAM MONITORING; COHERENT RADIATION; INTERFEROMETERS; MODULATION; REAL TIME SYSTEMS; ELECTROMAGNETIC RADIATION; MEASURING INSTRUMENTS; MONITORING; RADIATIONS; 426002* - Engineering- Lasers & Masers- (1990-)

Citation Formats

Salmon, Jr, J T. Apparatus and method for laser beam diagnosis. United States: N. p., 1991. Web.
Salmon, Jr, J T. Apparatus and method for laser beam diagnosis. United States.
Salmon, Jr, J T. Tue . "Apparatus and method for laser beam diagnosis". United States.
@article{osti_7027459,
title = {Apparatus and method for laser beam diagnosis},
author = {Salmon, Jr, J T},
abstractNote = {An apparatus and method are disclosed for accurate, real time monitoring of the wavefront curvature of a coherent laser beam. Knowing the curvature, it can be quickly determined whether the laser beam is collimated, or focusing (converging), or de-focusing (diverging). The apparatus includes a lateral interferometer for forming an interference pattern of the laser beam to be diagnosed. The interference pattern is imaged to a spatial light modulator (SLM), whose output is a coherent laser beam having an image of the interference pattern impressed on it. The SLM output is focused to obtain the far-field diffraction pattern. A video camera, such as CCD, monitors the far-field diffraction pattern, and provides an electrical output indicative of the shape of the far-field pattern. Specifically, the far-field pattern comprises a central lobe and side lobes, whose relative positions are indicative of the radius of curvature of the beam. The video camera's electrical output may be provided to a computer which analyzes the data to determine the wavefront curvature of the laser beam. 11 figures.},
doi = {},
journal = {},
number = ,
volume = ,
place = {United States},
year = {1991},
month = {8}
}