A Third Generation Water Bath Based Blackbody Source

Abstract

A third generation water bath based black-body source has been designed and constructed in the Radiometric Physics Division at the National Institute of Standards and Technology, Gaithersburg, MD. The goal of this work was to design a large aperture blackbody source with improved temporal stability and reproducibility compared with earlier designs, as well as improved ease of use. These blackbody sources operate in the 278 K to 353 K range with water temperature combined standard uncertainties of 3.5 mK to 7.8 mK. The calculated emissivity of these sources is 0.9997 with a relative standard uncertainty of 0.0003. With a 50 mm limiting aperture at the cavity; entrance, the emissivity increases to 0.99997.

A Second-Generation Blackbody System for the Calibration and Verification of Seagoing Infrared Radiometers

“…There are two approaches to managing the internal surface of a thermal infrared blackbody cavity: one can either choose a specular surface (e.g., Geist and Fowler 1986;Fowler 1995) or a diffuse surface (e.g., Mason et al 1996). Although specular paint surfaces are easier to model using Monte Carlo methods, diffuse paint gives a slightly higher emissivity.…”

“…The CASOTS-II water bath is not intended for use with synthetic oils that are used to reach temperatures above 373 K, as in some blackbody designs (Fowler 1996).…”

“…The CASOTS-II cavity was redesigned following a modified version of the cylindrical tube and cone blackbody cavity designed by Fowler (1995) in which the cylinder length is extended to be greater than the cone height. A general arrangement of the CASOTS-II cavity design is shown in Fig.…”

“…During the Committee on Earth Observation Satellites (CEOS) in situ radiometer intercalibration workshop (Kannenberg 1998), the CASOTS-I system demonstrated radiometric temperatures accurate to 60.02 K (Donlon et al 1999) using Marine-Atmospheric Emitted Radiance Interferometer (M-AERI; Minnett et al 2001) as a transfer radiometer when compared to a National Institute of Standards and Technology (NIST) blackbody unit (Geist and Fowler 1986;Fowler 1995). The CASOTS-I design was among several infrared blackbody sources evaluated in a second intercalibration exercise at the University of Miami in 2001.…”

10. The Calibration and Characterization of Earth Remote Sensing and Environmental Monitoring Instruments

“…Initially, the NIST water-bath blackbody [69] was used. More recently, the TXR was calibrated in the NIST Medium Background Infrared (MBIR) facility [70] using its cryogenic blackbody.…”