Gray-Body Radiation Using a Blackbody Source and an Optical Chopper
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- 作者：H. Rodríguez-Arteaga ; D. Cárdenas-García
- 关键词：Blackbody ; Emissivity ; Gray ; body ; Radiance temperature ; Transmittance
- 刊名：International Journal of Thermophysics
- 出版年：2015
- 出版时间：August 2015
- 年：2015
- 卷：36
- 期：8
- 页码：1757-1765
- 全文大小：534 KB
- 参考文献：1.D.P. DeWitt, F.P. Incropera, in Theory and Practice of Radiation Thermometry, chap. 1, ed. by D.P. DeWitt, G.D. Nutter (Wiley, New York, 1989), pp. 21-9
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5.ASTM Committee E20 on Temperature Measurement, E2758-10 (ASTM International, Conshohocken, PA, 2010) - 作者单位：H. Rodríguez-Arteaga (1)
D. Cárdenas-García (1)
1. Thermometry Division, Centro Nacional de Metrología, Carretera a Los Cues km 4.5, 76246, El Marqués, QRO, México - 刊物类别：Physics and Astronomy
- 刊物主题：Physics
Condensed Matter
Mechanics
Industrial Chemistry and Chemical Engineering
Physical Chemistry - 出版者：Springer Netherlands
- ISSN：1572-9567
文摘
The emissivity of most material surfaces that can be used as radiation sources is a function of wavelength. On the other hand, blackbody cavities with emissivities higher than 0.995 in a wide wavelength range are readily available in many laboratories. If it were possible to attenuate by a constant factor the radiation emitted by those blackbodies, then they could be used as gray-body radiators. A neutral density filter is not an option to attenuate the radiation from a blackbody source because its transmittance is wavelength dependent. Optical choppers, usually rotating disk shutters, are widely used to modulate the intensity of a light beam. The apparent transmittance of an optical chopper is defined in terms of the mark-to-space ratio. Most optical choppers have a 1:1 ratio which would be equivalent to 50 % transmittance. To attenuate the radiation coming from a blackbody, the optical chopper should have a stable rotating speed and a high chopping frequency so its mark-to-space cycle time is very short compared to a radiation thermometer response time. If this condition is fulfilled, the radiation thermometer would display a temperature reading as if it were aiming to a gray-body at the temperature of the blackbody and with an emissivity equal to the optical chopper transmittance. This method to obtain a gray-body radiator using a blackbody source and an optical chopper is discussed, and some measurements including its uncertainty analysis are reported. Keywords Blackbody Emissivity Gray-body Radiance temperature Transmittance