PURPOSE: To facilitate the positioning of the light receiving end of an optical fiber cable or the like irrespective of the direction of a sun light collecting device by a structure wherein regulating apertures capable of opening and closing are provided at least the eastern, western and northern sides of the basic part of the capsule.

CONSTITUTION: Because a lens 11 is controlled by means of a sun light direction sensor 12 so as to face toward the sun at all times, the focal point of the lens 11 or the light receiving end of the optical fiber cable locates at the western side in the morning, at the northern side during the day and at the eastern side in the evening. Consequently, the positioning of the light receiving end of the optical fiber cable can be easily performed, in whatever direction the sun light collecting device may be faced, by providing the regulating apertures 20 at the eastern, the western and the northern sides.