| 摘要 |
PURPOSE:To perform position detection and optical path correction efficiently without interrupting actual operation by forming a small hole for passing a light beam in the center of a pyroelectric crystal substrate and forming plural electrodes around the small holes radially in an electric insulation state. CONSTITUTION:A detecting device S for an invisible light beam has the small hole 2 in the center of the pyroelectric crystal substrate 1 and plural electrodes 3 are formed annularly on one surface of the substrate 1 at the periphery of the small hole 2; and a heat absorbing film 4 is formed on surfaces of the respective electrodes 3 and a common electrode 5 is formed on the other surface of the substrate 1. Detecting devices S are installed in the optical path of the invisible light beam opposite each other, and then when the axis of the light beam is aligned to the center P of the small hole 2, the irradiation distribution of the beam to each pyroelectric detection unit 6 becomes uniform and the output voltage of each unit 6 also becomes uniform, but when the beam axis deviates from the center P of the small hole, the output voltage distribution of each unit 6 has deviation and the direction and extent of the deviation of the axis of the light beam are discriminated on the basis of the deviation phase and output deviation. Therefore, the beam is irradiated in a specific direction by correcting the optical path so that the deviation is eliminated. |
