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Search Publications by: John H. Lehman (Fed)

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Displaying 126 - 150 of 312

Optical-Fiber Power Meter Comparison between NIST and KRISS

December 21, 2012
Author(s)
Seungkwan Kim, Keesuk Hong, Dong-Hoon Lee, David J. Livigni, Xiaoyu X. Li, John H. Lehman
We describe the results of a comparison of reference standards between the National Institute of Standards and Technology (NIST-USA) and Korea Research Institute of Standards and Science (KRISS- R.O. Korea). We report optical fiber-based power measurements

Laser power meter comparison at far infrared wavelengths and terahertz frequencies

August 1, 2012
Author(s)
John H. Lehman, Marla L. Dowell, Nina P. Basta, Kerry N. Betz, Erich N. Grossman
We have evaluated the responsivity of seven different detectors compared to an electrically calibrated photo-acoustic detector at 119 υm (2.5 THz) and 394 υm (0.76 THz) laser wavelengths. Among the detectors is an electrically calibrated thermopile having

Towards a fiber-coupled picowatt cryogenic radiometer

June 11, 2012
Author(s)
Nathan A. Tomlin, John H. Lehman, Sae Woo Nam
A picowatt cryogenic radiometer (PCR) has been fabricated at the microscale level for electrical substitution optical fiber power measurements. The absorber, electrical heater, and thermometer are all on a micromachined membrane less than 1mm on a side

Optical fiber-coupled cryogenic radiometer with carbon nanotube absorber

April 1, 2012
Author(s)
David J. Livigni, Nathan A. Tomlin, Christopher L. Cromer, John H. Lehman
A cryogenic radiometer was constructed for direct-substitution optical fiber power measurements. The cavity is intended to operate at the 3 K temperature stage of a dilution refrigerator or 4.2 K stage of a liquid cryostat. The optical fiber is removable

Optical fibre-coupled cryogenic radiometer with carbon nanotube absorber

March 2, 2012
Author(s)
David J. Livigni, Nathan A. Tomlin, Christopher L. Cromer, John H. Lehman
A cryogenic radiometer was constructed for direct-substitution optical-fibre power measurements. The cavity is intended to operate at the 3 K temperature stage of a dilution refrigerator or 4.2 K stage of a liquid cryostat. The optical fibre is removable

Carbon nanotube arrays for absolute IR and THz radiometry

October 2, 2011
Author(s)
John H. Lehman, Kerry N. Betz, Erich N. Grossman
We have assembled and evaluated a novel electrically calibrated thermopile having an array of 1.5 mm long multiwalled carbon nanotubes as the radiation absorber. We find very low reflectance at the 390 υm laser wavelength and excellent agreement between

Fully lithographic fiber-coupled cryogenic radiometer for picowatt powers

September 19, 2011
Author(s)
Nathan A. Tomlin, John H. Lehman, Sae Woo Nam
A new type of absolute cryogenic radiometer has been fabricated at the microscale level for direct substitution optical fiber power measurements. It consists of three parts: an absorber, electrical heater, and thermometer all on a single micro-machined

International comparisons of optical fiber power measurements

September 19, 2011
Author(s)
Igor Vayshenker, David J. Livigni, Xiaoyu X. Li, John H. Lehman
We discuss the results of optical fiber power meter (OFPM) measurements at 1310 and 1550 nm made by NIST and seven national measurement institutes (NMIs). We also describe transfer standards and the associated uncertainties. The comparisons show a
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