All-fiber-optic infrared multispectral radiometer for measurements of temperature and emissivity of graybodies at near-room temperature

Abstract

An all-fiber-optic infrared multispectral radiometer for measurements of temperature and emissivity of graybodies at near-room temperature was constructed. Different spectral regions in the radiometer were obtained by use of hollow glass waveguides (HGWs) as filters. Using HGWs instead of bulk filters was advantageous because each HGW can be used as two different spectral filters when a dual-band IR detector is used. In addition, HGWs are much cheaper than the bulk IR filters that are usually used in such applications. For one graybody with a mean emissivity of 0.71, the estimated mean errors obtained for sample temperature, ambient temperature, and sample emissivity for all measured temperatures were 0.50% (approximately 1.65 K), 0.48% (approximately 1.4 K), and 7.3% (approximately 0.052) respectively. For a second graybody with a mean emissivity of 0.8 the estimated mean errors were 0.35% (approximately 1.2 K), 0.48% (approximately 1.4 K), and 5.0% (approximately 0.04), respectively.

Measurements of the directional spectral emissivity based on a radiation heating source with alternating spectral distributions

“…Unlike the direct and indirect http://dx.doi.org/10.1016/j.ijheatmasstransfer.2015.07.064 0017-9310/Ó 2015 Elsevier Ltd. All rights reserved. measurement methods that are based on the emissivity definitions, the multi-wavelength method has been developed by some research groups [25][26][27][28][29][30][31][32][33] to simultaneously measure the sample temperature and the emissivity using an optimization algorithm that assumes the emissivity to be some approximate function of the wavelength. However, the reasonability of the assumed emissivity model for different materials is still an obstacle for accurate measurements of the emissivity.…”

Spectral stray light effect on high-temperature measurements using a near-infrared multi-wavelength pyrometer

“…As an improvement over one-color or two-color pyrometry, multi-wavelength pyrometry has been used to determine temperatures from spectral intensity measurements at different wavelengths [7][8][9][10][11][12][13][14][15][16][17][18][19][20][21][22][23][24][25][26]. More measurement information greatly reduces the effect of the uncertainty in the spectral emissivity.…”

“…Ng and Fralick [10] used a multi-wavelength pyrometer for temperature measurements of thermal barrier coatings, glass materials, and combustion gases. Katzir et al [12,13] developed four-band and multi-band fiber-optic radiometers for gray body temperature measurements at 5-20 lm. Madura et al [14] propose a method of correction of remote measurements of seawater surface temperature using multispectral IR pyrometer.…”

Absolute temperature measurements using a two-color QWIP focal plane array

“…If two bands are better than one, it stands to reason that more bands should be even more advantageous. Predictably, the potential benefits of an ever-greater number of spectral bands have indeed been explored [4], [5], [6] .…”