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Search Publications by: John R. Lawall (Fed)

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Displaying 26 - 50 of 53

Fabry-Perot Metrology for Displacements up to 50 mm

October 16, 2008
Author(s)
John R. Lawall
A system designed to apply Fabry-Perot interferometry to the measurement of displacements is described. Two adjacent modes of a Fabry-Perot cavity are probed, and both the absolute optical frequencies and their difference are used to determine

Laser Doppler vibrometer employing active frequency feedback

September 17, 2008
Author(s)
Akobuije D. Chijioke, John R. Lawall
We present a heterodyne Michelson interferometer for vibration measurement in which feedback is used to obviate the need to unwrap phase data. The Doppler shift of a vibrating target mirror is sensed interferometrically and compensated by means of a

How Accurately Can Your Interferometer Interpolate Fringes?

September 1, 2001
Author(s)
John R. Lawall
Optical interferometry is the means by which real-world displacements are measured relative to a standard reference wavelength. Most interferometers use a helium-neon laser and generate a signal with a period of half the wavelength, λ/2=316.5 nm. To

Ultrastable Laser Array at 633 nm for Real-Time Dimensional Metrology

July 1, 2001
Author(s)
John R. Lawall, J Pedulla, Y LeCoq
We describe a laser system for very high-accuracy dimensional metrology. A sealed-cavity helium-neon laser is offset-locked to an iodine-stabilized laser in order to realize a secondary standard with higher power and less phase noise. Synchronous averaging

Design and Evaluation of A Simple Ultralow Vibration Vacuum Environment

January 1, 2001
Author(s)
John R. Lawall, Ernest G. Kessler
A vibration-isolated platform in a high-vacuum environment designed for prototyping optical interferometers is described. The system provides isolation from both seismic and acoustic disturbances with a residual acceleration of 2.9 x 10 -6 m/s 2 rms (root

Ultrastable Laser Array at 633 nm for Real-Time Dimensional Metrology

January 1, 2001
Author(s)
Y Lecoq, J Pedulla, John Lawall
We describe a laser system for very high-accuracy dimensional metrology. A sealed-cavity helium-neon laser is offset-locked to an iodine-stabilized laser in order to realize a secondary standard with higher power and less phase noise. Synchronous averaging

Michelson Interferometry With 10 PM Accuracy

July 1, 2000
Author(s)
John R. Lawall, Ernest G. Kessler
We demonstrate a new heterodyne Michelson interferometer design for displacement measurements capable of fringe interpolation accuracy of one part in 36,000. Key to this level of accuracy are the use of two accousto-opic modulators for heterodyne frequency

A Frequency Stabilized Laser Array for Use in Displacement Metrology

February 17, 2000
Author(s)
J Pedulla, R Deslattes, John R. Lawall
We have developed a frequency stabilized laser system to supply light to measure atomic-scale displacements of a stage moved in real time. Each laser in the array provides enough power (~1 mW) for four Michelson interferometers whose accuracy requires a

A Frequency Stabilized Laser Array for Use in Displacement Metrology

February 1, 2000
Author(s)
J Pedulla, R Deslattes, John R. Lawall
We have developed a frequency stabilized laser system to supply light to measure atomic-scale displacements of a stage moved in real time. Each laser in the array provides enough power ({approximately equal to} 1 mW) for four Michelson interferometers