SAMPLING METHOD FOR OPTICAL FIBER TYPE TEMPERATURE SENSOR

PURPOSE:To remarkably improve lengthwise resolution without a rise in a manufacturing cost by making a cycle for outputting an optical pulse a non- integral multiple of a sampling cycle to be done after reception. CONSTITUTION:A laser diode 4 and photo diodes 8, 8 are connected to a terminal of a quartz optical fiber to be used as a sensor body via an optical branching filter. A cycle of the laser diode 4 for outputting optical pulses is made a non-integral multiple of a sampling cycle of an A/D-converter 10 for sampling signals of light intensity received by the photo diodes 8, 8. Thus by varying frequencies which determine both cycles slightly different from each other, a phase of the optical fiber in a lengthwise direction shifts slightly each time an optical pulse is generated, for example by 0.1 UT (1 UT is one sampling clock cycle). That is, distance resolution approximately 1/10 of distance resolution determined by the sampling cycle can be realized. That is, lengthwise resolution of the optical fiber can be remarkably improved.