Patent ID: 7218470
Filing Date: 2007-05-15
Classification: G11B

Abstract:
1. A method of forming a pattern of marks on a surface of a disk work piece, comprising: generating an electron beam modulated in accord with a desired pattern of marks to be formed on the disk work piece; producing relative motion, between the disk work piece and the modulated electron beam, while applying the modulated electron beam to the surface of the disk work piece to form the marks; and controlling duty cycle of the modulated electron beam in accord with a variation of speed of the relative motion, between the disk work piece and the modulated electron beam, wherein the step of controlling the duty cycle comprises controlling the duty cycle of the modulated electron beam in accord with radial distance of point of impact of the electron beam on the surface of the disk work piece from the center of the disk work piece in such a manner that the duty cycle is smaller for smaller radial distance and is larger for larger radial distance, to maintain a substantially constant electron exposure dose for marks to be formed on the disk work piece.