| 摘要 |
PURPOSE:To obtain exactly a central pattern and to improve positioning accuracy by using a sublimable plastic plate for a detecting piece of a laser light beam. CONSTITUTION:When a laser light beam 1 is irradiated to an acrylic resin plate 11, the acrylic resin at the irradiated point is easily heated up and sublimated to produce a circular pattern 12 corresponding to the diameter of the beam 1 and a funnel-shaped recess 13 therein. The recess 13 corresponds to the energy center of the beam 1 and since the energy density of the beam 1 is high, the elevation of the temp. is high and the rate of sublimation is correspondingly high, such recess is generated. Positioning is thus made possible by using the energy center of the beam 1 itself as a reference and the smaller pattern as a reference. |
