Abstract: An optical device includes a metal reflective layer substantially made of a metal material, a first light transmissive layer disposed on the metal reflective layer, an optical multilayer reflective film disposed on the first light transmissive layer and including a plurality of sublayers stacked on each other and having different refractive indexes, and a wavelength converting layer disposed on the optical multilayer reflective film and containing a fluorescent material capable of absorbing incident excitation light and generating fluorescent light having a lower energy. The wavelength converting layer is capable of generating mixed light containing the excitation light and the fluorescent light in response to irradiation with the excitation light.

Abstract: A semiconductor device having an output circuit includes a first field-effect transistor having a source connected to a line from which a first voltage is inputted, and a second field-effect transistor having a source connected to a drain of the first field-effect transistor, a gate connected to a data line from which a level signal is inputted, and a drain connected to an output terminal to which an output signal is outputted. A control unit controls a voltage at a gate of the first field-effect transistor when the second field-effect transistor is in ON state, so that a voltage at the drain of the second field-effect transistor is equal to a second voltage.

Abstract: A measuring tool for collecting down hole information, which essentially has a sensor sub including plural data collecting sensors secured at a forward portion of a drilling pipe and a sonde movable in the drilling pipe. Both the sensor sub and sonde employ a set of loop antennas to effect radiocommunication between them to thereby certainly send data detected by means of the sensors to the sonde.