BEAM IRRADIATION DEVICE, FOCUS CONTROLLER, OPTICAL DEVICE HAVING BEAM IRRADIATION DEVICE TO INFORMATION RECORDING MEDIUM, MANUFACTURE OF INFORMATION RECORDING MEDIUM MASTER DISK AND MANUFACTURE OF INFORMATION RECORDING MEDIUM

摘要

PROBLEM TO BE SOLVED: To make obtainable a minute beam spot and to surely and to make stably performable the focus control. SOLUTION: The beam irradiation device is provided with a beam generation source 41 generating at least any one of a light beam, an electron beam and an ion beam and a convergent lens 48 converging the beam from the beam generation source 41, and is constituted of providing at least first, second focus control mechanisms 71 and 72 respectively controlling the focus device of the beam to the same lens system constituting the convergent lens so as to focus the beam to a body 40 to be irradiated by the convergent lens 48.