Abstract: Disclosed is a light attenuator comprising a stick or rod composed of a light-transmitting material, and a light-attenuating layer composed of a thermoplastic resin and formed on at least one end face of the stick or rod, wherein finely divided particles having a light-absorbing or light-scattering property are uniformly incorporated in the thermoplastic resin. This light attenuator is made by forming a light-attenuating thermoplastic resin layer having incorporated therein the light-absorbing or light scattering finely divided particles on a release film or paper; placing the light-attenuating layer formed on the release film or paper on a heating plate; press-bonding the end face of a rod or stick composed of a light-transmitting material inserted and set in a ferrule to the surface of the release film or paper; cooling the bonded assembly; and then peeling the release film or paper to transfer the light-attenuating layer to the end face of the light-transmitting rod or stick.

Abstract: In apparatus for following sun light, at least two pairs of diametrically facing light-receiving elements (30a, 30c and 30b, 30d) are provided along the periphery of a circular end plane of incidence (24) of an optical fiber cable (20) where sun light is condensed by way of a lens 14. The deviation of a condensed light area from the circular end plane of incidence (24) will be effectively detected by the light-receiving elements to control a drive unit (46) which drives an equatorial (18) carrying an optical system including the lens (14) and the end plane of incidence (24) of the optical fiber cable (20). In one embodiment, another light-receiving element (50i) is provided at the center of the end plane of incidence (24) to detect when light condensing area is deviated to a great extent. The output signal of this light-receiving element (50i) is used to perform speed control of the drive unit (46). In another embodiment, a circuit arrangement for detecting abnormal state of the optical system is also used.

Abstract: Disclosed is a light attenuator comprising a stick or rod composed of a light-transmitting material, and a light-attenuating layer composed of a thermoplastic resin and formed on at least one end face of the stick or rod, wherein finely divided particles having a light-absorbing or light-scattering property are uniformly incorporated in the thermoplastic resin. This light attenuator is made by forming a light-attenuating thermoplastic resin layer having incorporated therein the light-absorbing or light-scattering finely divided particles on a release film or paper; placing the light-attenuating layer formed on the release film or paper on a heating plate; press-bonding the end face of a rod or stick composed of a light-transmitting material inserted and set in a ferrule to the surface of the release film or paper; cooling the bonded assembly; and then peeling the release film or paper to transfer the light-attenuating layer to the end face of the light-transmitting rod or stick.