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Search Publications by: Patrick Egan (Fed)

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Displaying 26 - 34 of 34

Metrology for comparison of displacements at the picometer level

July 31, 2014
Author(s)
Jack A. Stone Jr., Patrick F. Egan, Jay H. Hendricks, Gregory F. Strouse, Douglas A. Olson, Jacob E. Ricker, Gregory E. Scace, Donavon Gerty
An apparatus capable of comparing displacements with picometer accuracy is currently being designed at NIST. In principle, we wish to compare one displacement in vacuum to a second, equal displacement in gas, in order to determine gas refractive index. If

Picometer Metrology for Precise Measurement of Refractive Index, Pressure, and Temperature

December 18, 2013
Author(s)
Jack A. Stone Jr., Patrick F. Egan, Donavon Gerty, Jay H. Hendricks, Douglas A. Olson, Jacob E. Ricker, Gregory E. Scace, Gregory F. Strouse
Fabry-Perot interferometers can be used for very precise measurement of the refractive index of gasses. This can enable increased accuracy of interferometer-based length measurement. In addition, because the refractive index of a gas depends on its

Picometer metrology for precise measurement of refractive index, pressure, and temperature

July 14, 2013
Author(s)
Jack A. Stone Jr., Patrick F. Egan, Jay H. Hendricks, Gregory F. Strouse, Douglas A. Olson, Jacob E. Ricker, Gregory E. Scace
For several years we have been studying the use of Fabry-Perot interferometers for precise measurement of the refractive index of gasses, where the primary motivation has been to improve interferometer-based length measurement. Because the refractive index

Weak value thermostat with 0.2 mK precision

December 1, 2012
Author(s)
Patrick F. Egan, Jack A. Stone Jr.
A new laser-based thermostat sensitive to 0.2 mK at room temperature is reported. The method utilizes a fluid-filled prism and interferometric weak value amplification to sense nanoradian deviations of a laser beam: due to the high thermooptic coefficient

Absolute refractometry of dry gas to +-3 parts in 10 9

June 20, 2011
Author(s)
Patrick F. Egan, Jack A. Stone Jr.
We present a method of measuring the refractive index of dry gases absolutely at 632.8 nm wavelength using a Fabry-Perot cavity with an expanded uncertainty of -9 (coverage factor k = 2. The main contribution to this uncertainty is how well vacuum-to

An Optical Frequency Comb Tied to GPS for Laser Frequency/Wavelength Calibration

November 1, 2010
Author(s)
Jack A. Stone Jr., Patrick F. Egan
Optical frequency combs can be employed over a broad spectral range to calibrate laser frequency or vacuum wavelength. This article describes procedures and techniques utilized in the Precision Engineering Division of NIST (National Institute of Standards

Temperature stabilization system with millikelvin gradients for refractometry

July 25, 2010
Author(s)
Patrick F. Egan, Jack A. Stone Jr.
Refractometry of air is a central problem for interferometer-based dimensional measurements. Refractometry at the 10^{-9} level is only valid if air temperature gradients are controlled at the millikelvin level. Very precise tests of second-generation NIST

Calibrating Laser Vacuum Wavelength With a GPS-Based Optical Frequency Comb

May 15, 2007
Author(s)
Jack A. Stone Jr., Liang Lu, Patrick F. Egan
The Global Positioning System (GPS) can deliver an exceptionally accurate frequency standard to any point in the world. When we use the GPS signal to control an optical frequency comb, the comb+GPS system provides laser light with well-known frequencies