| 摘要 |
PURPOSE:To improve the yield of printed circuit boards by detecting the direct transmitted light from a laser oscillator and the transmitted light of the reflected light from a work surface respectively, computing the ratio of the quantities of the reflected light from the quantities of light of respective sensors and comparing the ratio with a reference value, then controlling the laser light. CONSTITUTION:The laser light 12 outputted from a CO2 laser oscillator 10 is directed by a partial transmission mirror 21 to the work 40, by which the work is irradiated with the laser light 14. This light is reflected as the reflected light 15 of the work and is partly transmitted through a partial reflecting mirror 21. The transmitted light 13 and the reflected light 16 are made into the wavelength components of the CO2 laser light by the effect of the partial reflecting mirror 21 and the quantities of the light are measured by the light quantity sensors 25A, 25B via condenser lenses 23, 24. The ratio of the signals is obtd. by a computing circuit 27 and is compared with the reference value 28 in a comparator circuit 29. A stop command is delivered to a control section 30 of the oscillator when the ratio of the reflected light increases. The visible light region is reflected and the laser light is directly reflected by a copper layer when the laser light arrives at this layer and, therefore, the laser light is stopped when an insulating material 41 is worked. |
