Apparatus and method for laser beam diagnosis

Patent · Tue Jan 01 00:00:00 EST 1991

OSTI ID:867948

Salmon, Jr., Joseph T. ^[1]

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1. (Livermore, CA)

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.

• Research Organization: Lawrence Livermore National Laboratory (LLNL), Livermore, CA (United States)
• DOE Contract Number: W-7405-ENG-48
• Assignee: United States of America as represented by United States (Washington, DC)
• Patent Number(s): US 5042950
• OSTI ID: 867948
• Country of Publication: United States
• Language: English

Related Subjects

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/