Abstract—The solar reflectors used in Concentrated Solar Power (CSP) technologies are either front-surface or second-surface mirrors. The advantage of second-surface mirrors over front-surface mirrors is due to the fact that the reflective layer in second-surface mirrors is covered from the front-side by glass, which allows protection against degradation factors and aggressive outdoor conditions. In this work, front surface mirrors and second-surface mirrors were prepared based on two reflective layers (Silver and Molybdenum). A comparison between the optical properties of the two mirrors’ architectures was conducted using a Perkin Elmer LAMBDA 950 UV/Vis/NIR Spectrophotometer. The results show that first-surface mirrors top-protected with amorphous Aluminum Oxide (1μm thick) layer show a higher specular reflectance compared to second-surface mirrors, which makes Al2O3-top-protected front-surface mirrors the best candidate in CSP application. The deposition of the Al2O3 layer was conducted using the Ion Layer Gas Reaction (Spray-ILGAR) technique, which did not alter the optical properties of the unprotected mirrors, conserving a high specular reflectance of the Silver-based first-surface mirrors (94% in the Near Infrared range).
Index Terms—Aluminum oxide, front-surface mirrors, molybdenum, protective layer, second-surface mirrors, silver, specular reflectance.
Houda Ennaceri is with the School of Science and Engineering of Al Akhawayn University, Ifrane 53000, Morocco (e-mail: h.ennaceri@aui.ma).
Abdelilah Benyoussef is with the Laboratory of Magnetism and Physics of the High Energies (L.M.P.H.E) within the Department of Physics of University Mohammed V-Agdal, Rabat 10000, Morocco (e-mail: benyous@fsr.ac.ma).
Ahmed Ennaoui is with the Helmholtz-Zentrum Berlin für Materialien und Energie (HZB), Berlin 14109, Germany (e-mail: ennaoui@helmholtz-berlin.de).
Asmae Khaldoun is with the Department of Physics within the School of Science and Engineering of Al Akhawayn University (AUI), Ifrane 53000, Morocco (e-mail: a.khaldoune@aui.ma).
[PDF]
Cite: Houda Ennaceri, Abdelilah Benyoussef, Ahmed Ennaoui, and Asmae Khaldoun, "Optical Properties of Front and Second Surface Silver-Based and Molybdenum-Based Mirrors," International Journal of Engineering and Technology vol. 8, no. 6, pp. 410-413, 2016.
