Polarization properties of a ‘Zeiss-type’ coelostat: The case of the solar tower in Arcetri

✍ Scribed by C. Capitani; F. Cavallini; G. Ceppatelli; E. Landi Degl'innocenti; M. Landi Degl'innocenti; M. Landolfi; A. Righini

• Publisher: Springer
• Year: 1989
• Tongue: English
• Weight: 848 KB
• Volume: 120
• Category: Article
• ISSN: 0038-0938
• DOI: 10.1007/bf00148542

✦ Synopsis

A theoretical model of the polarization properties of a 'Zeiss-type' coelostat is presented and discussed in detail. The Muller matrix describing the modification of the Stokes vector of the incident radiation as a result of the multiple reflections on the coelostat mirrors is derived as a function of the solar coordinates, the geometrical configuration of the coelostat, and the parameters defining the optical properties of the mirrors. These parameters, or more particularly, the index of refraction n and the extinction coefficient k, have been evaluated by means of laboratory measurements performed on a series of specimens having characteristics similar to those of the coelostat mirrors. The geometry of the coelostat configuration is described in full detail. The theoretical model has been then particularized to the case of the Donati Solar Tower in Arcetri, and some experimental measurements have been performed to check the correctness of the mode1. These measurements show the basic adequacy of the mathematical model, although some offset terms are found in the Stokes parameters U and V.