Abstract: A measurement head in an arc welding machine modulates the light intensity of a laser light beam with a modulating signal of 50 KHz or higher, and radiates the laser light beam onto an object to be measured while changing the direction of laser beam emission in one plane. A light receiving unit in the measurement head changes its direction of detecting a reflected beam in the same plane. Angles at which the light beams are emitted and detected are detected at the time a modulated signal component is detected from an output from the light receiving unit. The position of a bright spot produced on the surface by the radiated laser light beam is computed from the detected angles based on the principle of triangulation.

Abstract: A pair of deflection electrodes at least one of which is grooved are provided to confront with each other in an ink jet system printer in order to deflect charged ink droplets emitted from a nozzle as they pass through a high voltage electric field established therebetween. Objectionable ink mist, which is unavoidably formed and diffused in various directions after the ink droplets impinge upon a recording paper or a beam gutter, attached to the grooved deflection electrode gathers and forms an ink drop, which is collected in an indent formed in the grooved deflection electrode. This precludes erroneous breaking down of the system and ensures stability of the high voltage electric field established between the pair of deflection electrodes.