Fiber Optic Daylighting System using Parabolic Reflector
Parabolic dish-based daylighting systems have been demonstrated and studied in detail, but efficiency of the system was not discussed in depth. One of the reasons was that an efficient optical simulation tool was not used. In this research, efficiency of the system was improved, and all losses were considered. Sunlight is captured, guided, and distributed through the parabolic reflector, optical fibers, and plano-concave lens, respectively. At the capturing stage, uniform illumination solves the heat problem, which has critical importance in making the system cost-effective by introducing plastic optical fibers. The efficiency of the system is increased by collimated light, which helps to insert maximum light into the optical fibers.
Concept of making uniform and collimated light
The idea behind the system is to capture sunlight and then focus it over a small area. The light is guided through optical fibers and distributed at the building’s interior. For daylighting systems, uniform illumination is mandatory at the capturing and distributing stages. A parabolic mirror captures sunlight and directs the light towards a second mirror, which illuminates the bundle of optical fibers.
Concave and convex parabolic reflectors are appropriate to produce collimated light. Maximum sunlight is exposed to the bundle of optical fibers by arranging the fibers in a circular shape. The focal points of both reflectors must be at the same point to make collimated light. The diameter of the receiver and the diameter of the convex reflector should be same to make uniform light on the bundle of optical fibers.
Concept of uniform light distribution in the interior
To spread the light at the destination, the optical fibers were divided into different bundles, and the fibers in each bundle were organized into a circular shape. A diverging lens was mounted at the end of each bundle. A biconcave lens was selected to diverge the incoming light from the optical fibers.