Measurement of Reflectance Covering UV to MIR of Solar Selective Coatings by One Fourier Transform Spectrometer

The reflectance of solar selective coating, covering UV to MIR bands, is measured by only one Fourier Transform (FT) spectroscope. The measurement is done for different wavelength ranges from 0.3 to 20 μm and different surface morphologies of substrate by different optical accessories. For flat smooth substrate, the reflectance of UV and VIS bands is measured by near normal relative reflectance accessory for mirror reflection, and that of NIR and MIR bands is measured by VW absolute reflectance accessory. For rough or curved substrate, the reflectance from UV to VIS is measured by white sphere accessory, and that of NIR and MIR is measured by gold sphere accessory. The sample holder is customized for the measurement of tubular substrate, and data in different bands is carefully calibrated with high reflection reference line and zero baseline approximation. Aluminum and gold coated mirrors are used for calibration in UV-VIS and NIR-MIR bands respectively. The reflectance of sample holder without any samples is considered as zero baseline. Smooth reflectance curves from 0.3 to 20 μm are obtained for solar selective coatings which are deposited on the flat smooth, rough and tubular substrates, respectively.