| Summary: | 碩士 === 國立臺灣科技大學 === 電子工程系 === 99 === At present, energy shortages and green awareness have led to increased use of solar energy. The energy available from the sun is inexhaustible, with many possible applications. How to capture natural light and improve the efficiency of its use are important questions for engineers.
This paper presents a freeform lens concentrator structure. This optical unit has a high light gathering efficiency, which can effectively collect the sun's rays and can increase the power generated by sunlight. This is accomplished by using a circular structure, made in modular, movable units, which can be assembled into a cascadable concentrator system.
This optical disc device will have a single output port in the center of the circle. We define an index to calculate the energy density of the light gathered by the concentrator. This index indicates the collected sunlight’s lumens per unit area at the concentrator output port (lm/mm2). By the value of this indicator we assess the level of collection efficiency. For example as in the disc concentrator design we use in this paper, from a light gathering area of 0.09 m2, we can get 1300 lumens light output at the export, which has a radius of 3 mm, that is, the optical energy density is nearly 46 lm/mm2, so that the energy conversion efficiency can easily provide for indoor lighting needs, and provide more than 50 times more light energy than the traditional static-type concentrator.
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