| 摘要 |
PURPOSE:To improve the accuracy in detecting a mark position by finding the correlation of the range decided by a mark width and laser spot diameter from the detection signal data of the laser reflection light of an object and finding the mark center. CONSTITUTION:Laser light is projected/scanned on the circuit board 18 as an object and the reference signal from a beam splitter 15 and the detection signal from reflected laser light are inputted to a controller 11. The detection signal and reference signal inputted to the amplifier 71 of the controller 11 are inputted to a CPU after their A/D convertion. Also, the positional pulse fed from an XY stage 17 is inputted to a CPU 76 via a pitch setting circuit 74 and a positional coordinate value via a latch circuit 72 respectively. A mark positional center is thus obtd. by finding the mark width from the detection signal data and the extreme value of the correlation of the range decided from the laser spot diameter. The mark positional detection accuracy is therefore improved. |
