| 摘要 |
PURPOSE:To eliminate thermal damages of a cut face and to permit cutting with high accuracy by providing a light absorbing part having the light reflectivity lower than the light reflectivity of a thin ferromagnetic metallic film layer on a substrate so as to co-exist with the thin ferromagnetic metallic film layer and projecting a laser beam to the light absorbing part, thereby cutting the substrate to a prescribed shape. CONSTITUTION:A raw sheet 16 of a magnetic recording medium formed with the thin ferromagnetic metallic film layer 14 and the band-shaped light absorbing part 15 not formed with the thin ferromagnetic metallic film layer on the substrate 4 in such a manner that said layer and part co-exist is formed. Cutting of such sheet is execute by converging the laser beam from a laser oscillation tube by a condenser lens mounted in a gas nozzle-shaped processing head 18, projecting converged light 20 to the raw sheet 16 of the magnetic recording medium made to travel below the processing head 18 and locally heating the light absorbing part 15 which is the surface to be irradiated with the laser beam to a high temp., thereby liquefying or gassifying said part or converting said part to plasma to execute separation and removal. The cutting is thereby executed at the suppressed thermal damages with the high accuracy.
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