Disco Corporation

Chikara Aihara

Tomohiro Endo

A method of detecting a transmission laser beam is disclosed. A laser beam of a wavelength having a transparency to a plate-shaped workpiece having a first face and a second face is irradiated upon the workpiece from the first face side with a focal point of the laser beam positioned in the inside of the workpiece. The laser beam is detected after it has passed through the workpiece to the second face side. A photosensitive sheet is positioned to hold the workpiece on a holding face of a chuck table. A photosensitive layer between the sheet and the workpiece is opposed to the second face of the workpiece. The laser beam is irradiated from the first face side of the workpiece, and the state of the transmission laser beam from a photosensitive reaction region formed in the photosensitive layer of the photosensitive sheet is confirmed.

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Tokyo, Japan

Chikara Aihara