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Title: Apparatus and method for laser beam diagnosis

Abstract

An apparatus and method is 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.

Inventors:
 [1]
  1. (Livermore, CA)
Issue Date:
Research Org.:
Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
OSTI Identifier:
867948
Patent Number(s):
5042950
Assignee:
United States of America as represented by United States (Washington, DC)
DOE Contract Number:  
W-7405-ENG-48
Resource Type:
Patent
Country of Publication:
United States
Language:
English
Subject:
apparatus; method; laser; beam; diagnosis; disclosed; accurate; time; monitoring; wavefront; curvature; coherent; knowing; quickly; determined; collimated; focusing; converging; de-focusing; diverging; lateral; interferometer; forming; interference; pattern; diagnosed; imaged; spatial; light; modulator; slm; output; image; impressed; focused; obtain; far-field; diffraction; video; camera; ccd; monitors; provides; electrical; indicative; shape; specifically; comprises; central; lobe; lobes; relative; positions; radius; provided; computer; analyzes; data; determine; relative position; coherent laser; light modulator; interference pattern; video camera; laser beam; electrical output; relative positions; diffraction pattern; output indicative; time monitoring; quickly determine; field pattern; /356/

Citation Formats

Salmon, Jr., Joseph T. Apparatus and method for laser beam diagnosis. United States: N. p., 1991. Web.
Salmon, Jr., Joseph T. Apparatus and method for laser beam diagnosis. United States.
Salmon, Jr., Joseph T. Tue . "Apparatus and method for laser beam diagnosis". United States. https://www.osti.gov/servlets/purl/867948.
@article{osti_867948,
title = {Apparatus and method for laser beam diagnosis},
author = {Salmon, Jr., Joseph T.},
abstractNote = {An apparatus and method is 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.},
doi = {},
journal = {},
number = ,
volume = ,
place = {United States},
year = {1991},
month = {1}
}

Patent:

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