摘要 |
PROBLEM TO BE SOLVED: To enhance a jitter characteristic by reducing an exposure amt. of a laser beam during only a period excluding a prescribed time after rising of a pulse of a pulse signal for controlling the intensity of the laser beam in an exposure process and a prescribed time before falling of the pulse. SOLUTION: The exposure amt. of the laser beam emitted from a laser beam recorder driven and controlled by a pulse signal T0 to a photoresist film fixed by baking the film formed on the surface of a glass disk is controlled. The prescribed times Th and Tt after rising and before falling of the pulse signal T0 respectively are made to be two to four times as long as a basic clock T, and the exposure is performed at full power, and is performed at lower power reduced by 10% to 20% for the remaining period. Then, the pulse signal T0 is generated by a control circuit using an AND circuit, an attenuator and an arithmetic circuit and inputting an original signal of pulse width T0 and a signal delayed by the time Th and Th+Tt. Consequently, the jitter characteristic is enhanced. |