| 摘要 |
PROBLEM TO BE SOLVED: To obtain a sunlight collector which is capable of always stably collecting the sunlight without being affected by the seasonal changes and date and time changes of the sun position by providing the device with plural lenses in such a manner that the focal positions of the respective lenses are offset to a lens direction or an optical fiber side with respect to the end face position of an optical fiber. SOLUTION: Five elements of the lenses 12a to 12e are disposed in order to collect the sunlight 11. The respective lenses 12a to 12e are so disposed that the optical axes Oa to Oe of the respective lenses 12a to 12e are offset in the lens direction with respect to the central position fc at the end face of the optical fiber 14. The plurality of lenses 12a to 12e are so arrayed that the offset quantity L between the focal positions of the respective lenses 12a to 12e and the end face position of the optical fiber 14 is expressed by the equation using the numerical aperture NA of the lenses 12a to 12e and the core diameter D of the optical fiber 14. The optical fiber 14 for transmitting the collected light is preferably an optical fiber which is made of a resin and has a core diameter of 3 to 20 mm.
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