Effect of polytetrafluoroethylene (PTFE) phase transition at 19°C on the use of Spectralon as a reference standard for reflectance.
Effect of polytetrafluoroethylene (PTFE) phase transition at 19°C on the use of Spectralon as a reference standard for reflectance.
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DOI：
10.1364/ao.52.004806
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发表时间：
2013-07
期刊：
影响因子：
1.9
通讯作者：
C. Ball;A. Levick;E. Woolliams;P. Green;M. Dury;R. Winkler;A. Deadman;N. Fox;M. King
中科院分区：
文献类型：
--
作者：
C. Ball;A. Levick;E. Woolliams;P. Green;M. Dury;R. Winkler;A. Deadman;N. Fox;M. King
烧结聚四氟乙烯(PTFE)具有高反射性，被广泛用作遥感、辐射测量和光谱分析的参考标准。在单色波长633 nm处，测量了聚四氟乙烯积分球在19℃的室温相变过程中输出通量的相对变化量为1.82±0.21%。输出通量的变化是由于相变引起材料密度的变化，使PTFE的半球面总反射率发生了0.09±0.02%的微小变化。对于大多数用户来说，测量的总半球反射率的这种微小变化不太可能显著影响用作参考标准的聚四氟乙烯平板反射器的精度。然而，由于积分球腔内发生的多次反射，当聚四氟乙烯积分球需要在接近19°C相变的温度下对通量、辐照度或辐射度进行高精度(<；5%)测量时，应通过数学校正或通过积分球的温度稳定来实施补救措施。
Sintered polytetrafluoroethylene (PTFE) is highly reflective and is widely used as a reference standard in remote sensing, radiometry, and spectroscopy. The relative change in output flux from a PTFE integrating sphere over the room temperature phase transition at 19°C has been measured at a monochromatic wavelength of 633 nm as 1.82±0.21%. The change in output flux was attributed to a small change of 0.09±0.02% in the total hemispherical reflectance of PTFE, caused by a change in its material density as a result of the phase transition. For the majority of users, this small change measured in total hemispherical reflectance is unlikely to impact significantly the accuracy of PTFE flat panel reflectors used as reference standards. However, owing to the multiple reflections that occur inside an integrating sphere cavity, the effect is multiplied and remedial action should be applied, either via a mathematical correction or through temperature stabilization of the integrating sphere when high accuracy (<5%) measurements of flux, irradiance, or radiance are required from PTFE-based integrating spheres at temperatures close to the phase transition at 19°C.