Achromatic self-referencing interferometer

Patent · Sat Jan 01 00:00:00 EST 1994

OSTI ID:869244

Feldman, Mark ^[1]

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1. Pleasanton, CA

A self-referencing Mach-Zehnder interferometer for accurately measuring laser wavefronts over a broad wavelength range (for example, 600 nm to 900 nm). The apparatus directs a reference portion of an input beam to a reference arm and a measurement portion of the input beam to a measurement arm, recombines the output beams from the reference and measurement arms, and registers the resulting interference pattern ("first" interferogram) at a first detector. Optionally, subportions of the measurement portion are diverted to second and third detectors, which respectively register intensity and interferogram signals which can be processed to reduce the first interferogram's sensitivity to input noise. The reference arm includes a spatial filter producing a high quality spherical beam from the reference portion, a tilted wedge plate compensating for off-axis aberrations in the spatial filter output, and mirror collimating the radiation transmitted through the tilted wedge plate. The apparatus includes a thermally and mechanically stable baseplate which supports all reference arm optics, or at least the spatial filter, tilted wedge plate, and the collimator. The tilted wedge plate is mounted adjustably with respect to the spatial filter and collimator, so that it can be maintained in an orientation in which it does not introduce significant wave front errors into the beam propagating through the reference arm. The apparatus is polarization insensitive and has an equal path length configuration enabling measurement of radiation from broadband as well as closely spaced laser line sources.

• 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 5305074
• OSTI ID: 869244
• Country of Publication: United States
• Language: English

Related Subjects

achromatic
self-referencing
interferometer
mach-zehnder
accurately
measuring
laser
wavefronts
broad
wavelength
range
example
600
nm
900
apparatus
directs
reference
portion
input
beam
arm
measurement
recombines
output
beams
arms
registers
resulting
interference
pattern
interferogram
detector
optionally
subportions
diverted
third
detectors
respectively
register
intensity
signals
processed
reduce
sensitivity
noise
spatial
filter
producing
quality
spherical
tilted
wedge
plate
compensating
off-axis
aberrations
mirror
collimating
radiation
transmitted
thermally
mechanically
stable
baseplate
supports
optics
collimator
mounted
adjustably
respect
maintained
orientation
introduce
significant
wave
front
errors
propagating
polarization
insensitive
equal
path
length
configuration
enabling
broadband
closely
spaced
line
sources
mechanically stable
spatial filter
output beams
radiation transmitted
reference portion
wave front
wavelength range
input beam
interference pattern
path length
output beam
closely spaced
accurately measuring
measuring laser
line source
filter output
mach-zehnder interferometer
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