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Displaying 251 - 275 of 351

Characterization of High-OD Ultrathin Infrared Neutral Density Filters

October 8, 1998
Author(s)
Simon G. Kaplan, Leonard M. Hanssen, Alan L. Migdall, G Lefever-Button
We have performed transmittance measurements of metal-film neutral density filters on ultrathin polymer substrates using both Fourier-transform infrared spectrometer and laser-based (3.39 mm and 10.6 mm) systems. The use of ultrathin substrates, free of

Characterization of Narrow-Band Infrared Interference Filters

October 8, 1998
Author(s)
Simon G. Kaplan, Leonard M. Hanssen
A Fourier-transform infrared (FT-IR) spectrophotometer system is used to measure the transmittance of infrared band-pass filters as a function of wavelength, temperature, and beam geometry. Measurements are performed using an f/4 beam geometry at normal

FT-IR Based Polarimeter with High-Quality Brewster-Angle Polarizers

October 8, 1998
Author(s)
Simon G. Kaplan, Leonard M. Hanssen
A Fourier transform infrared (FT-IR) spectrometer based broadband infrared polarimeter has been developed around a pair of high-quality Brewster angle polarizers. These polarizers consist of four Ge plates in a chevron geometry and have been measured to

Normal Infrared Spectral Emittance of Al 2 O 3

October 8, 1998
Author(s)
Simon G. Kaplan, Leonard M. Hanssen
We have measured the near-normal ordinary ray transmittance and reflectance of crystalline Al 2O 3 from 1.6 m to 11 m and temperatures from 296 K to 582 K. The absorptance, or emittance, is derived from 1-(T+R), where T and R are the measured transmittance

InSb Working Standard Radiometers

October 1, 1998
Author(s)
George P. Eppeldauer, Alan L. Migdall, Leonard M. Hanssen
Standard quality InSb radiometers have been developed and characterized at the national Institute of Standards and Technology (NIST). The InSb radiometers will hold the recently realized spectral response scale of the NIST and will serve as working

Absorption Line Evaluation Methods for Wavelength Standards

July 22, 1998
Author(s)
C. J. Zhu, Leonard M. Hanssen
Two methods for absorption line (peak) evaluation based on center of gravity (CG) calculations are described and compared using spectra of the NIST standard reference material (SRM) 1921(a) characterization measurements. These methods are (1) calculating

The Magnification of Conic Mirror Reflectometers

July 1, 1998
Author(s)
K A. Snail, Leonard Hanssen
Conic mirror reflectometers are used to measure the diffuse reflectance and total integrated scatter of surfaces. In spite of the long history of using conic mirrors for these purposes, the maximum magnification of the three primary types of conic mirrors

Infrared Diffuse Reflectance Instrumentation and Standards at NIST

June 29, 1998
Author(s)
Leonard M. Hanssen, Simon G. Kaplan
A spectrophotometer system for spectral characterization of materials in the infrared has been built around a bench-top Fourier transform (FTIR) instrument. Its capabilities include the measurement of directional-hemispherical reflectance from 1 *m to 18