| Summary: | 碩士 === 國立成功大學 === 微電子工程研究所碩博士班 === 100 === In order to alleviate the energy and environmental pollution impacts being placed upon our society, efficient LED lighting systems and sunlight collector has steadfastly emerged to be the viable solutions we could rely upon. However, simply relying on a single LED and a solar cell alone may not be able to meet the expectations of lighting in a locally confined area and a large sunlight collection area, except a further improvement is adopted by incorporating the design of secondary optics. With regards to the secondary optics, a conventional wisdom is to rely on the secondary optical freeform lens design method by using a rather complex mathematical model entailed with the expenses of the added complexity and long design hours.
Therefore, in this thesis a new freeform lens design method is proposed based instead on a set of simple mathematical equations coupled with an innovative ray tracing technique by generating a two-dimensional freeform curve traced out by rotating either a reference vertical or horizontal tangential plane. In order to verify this ray tracing method, the two different freeform lenses are specifically designed and fabricated for the LED and solar cell, and a cross comparison is then established between the simulation and experimental results aided by the use of the optical TracePro simulation software.
First, the white LED freedom lens designed with TracePro theoretically demonstrates that its polar candela distribution of half-angle falls in a range of 0° to 42°, while the experimental measurement result verifies later that the polar candela distribution in terms of the half-angle is within a range between 0° and 43°. Notice that two sets of results agree quite nicely with each other. As for the solar cell, giving the combined advantages of the highly uniform irradiance, a locally light-converging capability and a geometrical concentration of 100× delivered by the freeform lens, the TracePro simulation has verified that with wavelength λ = 550nm and AM1.5D separately imposed, the resultant optical efficiencies simulated are as 81.5% and 72.1%, respectively, while the irradiance uniformity of the solar cell light absorption are obtained as 94.83% and 76.53%, respectively.
Finally, the single crystalline silicon and III-V compound semiconductor triple-junction solar cell coupled with the freeform lens are also measured by varying the temperature and the light concentration ratio. The measurement result has shown that for the III-V triple-junction solar cell, its conversion efficiency can be effectively enhanced from 21.52% to 25.53% when the freeform lens is incorporated.
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