Design and ray tracing of multifaceted Scheffler reflector with novel crossbars

In this paper, a detailed design methodology of a novel and simple crossbar design for error-free Scheffier reflector profile is presented. The present work is undertaken to improve the existing crossbar design, which requires a three-point circular approximation of original elliptical crossbars. This approximation introduces a small error in the Scheffier profile. The proposed new crossbars are part of circles formed by the interception of a horizontal plane with paraboloid leading to an error-free Scheffler profile. Implicit equations involving various design parameters are solved iteratively and the prediction equations have been developed for inclination angle as a function of non-dimensional aperture radius and x-intercept as a function of inclination angle. Design charts for selecting radius, width and length of novel crossbars have also been developed. In addition, sections on seasonal tracking and reflector surface optimization and ray tracing are included with a focus on mirror (facet) size selection, arrangement of mirrors to avoid wrinkling in Scheffier profile, effect of mirror size on focus, focal shift due to delay in seasonal adjustments and the tracking mechanism for achieving fixed focus throughout the year. A MATLAB code for ray tracing of multifaceted Scheffier reflector for seasonal variation is provided along with this paper.