3 edition of 45⁰/0⁰ reflectance factors of pressed polytetrafluoroethylene (PTFE) powder found in the catalog.
45⁰/0⁰ reflectance factors of pressed polytetrafluoroethylene (PTFE) powder
by U.S. Dept. of Commerce, Technology Administration, National Institute of Standards and Technology, For sale by the Supt. of Docs., U.S. G.P.O. in Gaithersburg, MD, Washington, DC
Written in English
|Statement||P. Yvonne Barnes and Jack J. Hsia.|
|Series||NIST technical note -- 1413.|
|Contributions||Hsia, J. J., National Institute of Standards and Technology (U.S.)|
|The Physical Object|
|Pagination||iv, 13, 102 p.|
|Number of Pages||102|
Its reflectance is equal to 1 and its BRDF is 1/π for every couple of incidence and reflection directions. In practice, white standards approaching these properties are made of pressed barium sulfate or PTFE (known as Algoflon, Halon, or Spectralon). They must be calibrated in terms of the perfectly reflecting diffuser. The object to assess. transfer from pressed PTFE, and determined to be The uncertainty due to the difference in sphere geometries of the commercial spectrophotometer used in the skin reflectance study and NIST ST ARR, which was used to establish the reflectance scale for the sintered PTFE standard, was evaluated by comparing reflectance factors of a NIST-owned.
Spectralon Diffuse Reflectance Standards can offer the highest diffuse reflectance values of any known substance. These durable, chemically inert standards can have typical reflectance values ranging from 1% to 50% and are spectrally flat over the UV-VIS-NIR spectrum. Light that falls on a surface can either be absorbed, transmitted or reflected, depending on the properties of the material involved. Reflection factors (r), absorption factors (a) and transmission factors (t) can be between 0 and 1 (0 %). The sum of the three factor is always 1. The transmitted or reflected radiation can be regular (1), scattered (2) or completely diffuse (3).
Figure 1 Principle of backscattered reflectance for transmitting particles. FACTORS AFFECTING INFRARED REFLECTIVITY Figure 2 Near-infrared reflectance spectra of nanocrystalline metal oxides and macrocrystalline metal oxides; the reflectance of PTFE (reference) is about . This practice covers procedures for the preparation and use of acceptable transfer standards for NIR spectrophotometers. Procedures for calibrating the reflectance factor of materials on an absolute basis are contained in CIE Publication No. 44 (9).Both the pressed powder samples and the sintered PTFE materials are used as transfer standards for such calibrations because they have very.
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The bidirectional reflectance factor is reported for, and nm at angles of incidence of - 10,and ° and at viewing angles at 10° intervals from to +80°. INTRODUCTION The reflection properties of pressed polytetrafluoroethylene (PTFE) powder.
in the ultraviolet, visible, and near-infrared. Pressed polytetrafluoroethylene (PTFE) powder is commonly used as a reflectance standard for bidirectional and hemispherical geometries. The wavelength dependence of the reflectance factor of PTFE is presented for the near-infrared spectral region ( nm to nm) for the 45°/0° geometry, as well as in the visible spectral region ( nm to nm) for comparison with previously published.
Pressed polytetrafluoroethylene (PTFE) powder is commonly used as a reflec- tance standard for bidirectional and hemi- spherical geometries.
The wavelength de- pendence of the reflectance factor. The 45 ° /0 ° reflectance factor of pressed Algo-Flon (F5) PTFE powder 1 over the spectral range of nm to nm is presented here.
These measurements are intended to show the general trend of the wavelength dependence of PTFE for the 45 ° /0 ° reflectance factor in. An illustration of an open book. Books.
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45⁰/0⁰ reflectance factors of pressed polytetrafluoroethylene (PTFE) powder [microform]  Barnes, P. Yvonne. The reflection properties of pressed polytetrafluoroethylene powder have been under investigation by the Radiometric Physics Division at the National Bureau of Standards for the past five years.
This material has a great potential use, both as a standard of diffuse reflectance and as a coating for integrating spheres for applications in reflectance spectrophotometry and other signal-averaging.
The object of this paper is to present results of several experiments relating to the preparation and use of pressed polytetrafluoroethylene (PTFE) powder as a diffuse reflectance standard for the.
Reflectance spectra for pressed polytetrafluoroethylene powder (alter Weidner and Hsia, ). to be accurately known to obtain R(Oh) for each wavelength interval of the radiometer. Field goniometer The first step in obtaining R(OO) for a reference panel is to evaluate its non- lambertian properties over a range of sun/panel incidence angles.
Ratio R 0 / 45 / R 6 / di of spectral reflectance factor obtained using the 0/45 geometry to that obtained using the 6/di geometry as a function of wavelength λ of sintered PTFE, pressed PTFE, and ceramic samples. (The scale for this figure was chosen to depict the overall trend of the ratios across the spectral region; consequently, the ratio.
PTFE offers nearly ideal Lambertian properties and high reflectance values (95–99% for white surfaces) over a broad spectral range (– nm). The primary disadvantage of PTFE is the higher cost, with secondary factors including the need to maintain a. Get this from a library. 45°/0° reflectance factors of pressed polytetrafluoroethylene (PTFE) powder.
[P Yvonne Barnes; J J Hsia; National Institute of Standards and Technology (U.S.)]. V.R. Weidner, J.J. Hsia and B. Adams, Laboratory intercomparison study of pressed polytetrafluoroethylene powder reflectance standards, Appl. Opt. 24. The expanded uncertainty at a coverage factor of two for the 45°/0° reflectance factors of pressed PTFE powder ranges from 0, to 0, This report was prepared by P.Y.
Barnes, USA and J.J. Hsia, USA (Reprint of NIST Technical Note July ). Directionally dependent reflectance changes in the directional reflectance properties of pressed and sintered optical grade PTFE diffuser standards were studied in three aspects. First, change in BRDF after VUV irradiation; (2) change in reflectance after bake-out; and (3) change in BRDF after irradiating a contaminated diffuser with VUV source.
The reference for this method is the hemispherical reflectance of pressed polytetrafluoroethylene (PTFE) powder prepared according to National Institute of Standards and Technology (NIST) directions. The panels and a radiometer are mounted on rotation stages to measure the reflectance factor at different incidence angles for a normal view angle.
Reflection factor = luminous flux reflected by a body / luminous flux received by the body. The ratio of the total amount of radiation, as of light, reflected by a surface to the total amount of radiation incident on the surface. In other words, it is the fraction of radiant energy that is reflected from a surface.
Pressed polytetrafluoroethylene (PTFE) powder is commonly used as a reflectance standard for bidirectional and hemispherical geometries.
The wavelength dependence of the reflectance factor of PTFE is presented for the near-infrared spectral region ( nm to nm) for the 45 degrees/0 degrees geometry, as well as in the visible spectral. Panel Reflectance and Occlusion of Solar Disk  Uncertainty in the panel reflectance is conservatively estimated as 2%.
This value is based upon the relative agreement between five laboratories participating in a panel calibration round‐robin experiment [Early et al., ].The average difference between the Remote Sensing Group at the University of Arizona and the National. Most of these calibrations are done with an 8/d, 8° incidence, diffuse hemispherical (sphere-based) reflectance measure as referenced to a “Lambertian standard” (sintered PTFE or pressed PTFE).
Technically, this is an 8/d reflectance factor due to the ratio to the Lambertian material, but this distinction will not be discussed in this paper. High-performance commodity polymers are in demand due to low cost, durability, easy productivity, and recycling ability.
This article comprises a survey on the performance properties of polytetrafluoroethylene (PTFE) fluoropolymer. It is a well-known choice for coatings, insulation, thermal sealing, lubrication, bearings, and clinical applications. Sources of uncertainty are the directional-hemispherical spectral reflectance factor of the sintered PTFE standard, the sphere geometry, the wavelength, and random effects.
The standard uncertainty due to the reference standard was evaluated during the scale transfer from pressed PTFE and determined to be The dielectric property relations of a series of BaTiO 3 –polymer composites with a uniquely high-volume fraction of ceramic [(1 − x)BaTiO 3 –x polytetrafluoroethylene (PTFE), with volume fractions x =,and ] are studied.
Such high-volume fraction of the BaTiO 3 phase is achieved by using the cold sintering process, as it enables a single-step densification of .