Harness, Dickey & Pierce, P.L.C.
Recording apparatus
 A recording apparatus locates a photo detector at a predetermined position on an optical base, stopping the rotation of a resist master disk, activating a focusing laser, and optimally positioning a head by means of a head slider control circuit. The resist master disk then starts to rotate, followed by the starting of a focus servo circuit. A focus fine adjust circuit effects a fine movement of the photo detector using positioning data to achieve optimum focusing. A differential amplifier serves to cause a recording lens to adjust to nullify the error signal. Display information is compared with the focusing position data and, when the numerical information coincides with the focusing position data, the above-mentioned focusing data is used as optimum focusing position data for the initial setting of the optimum focusing position. The use of optimum focusing position data in the form of numerical values permits easy initial setting of the optimum focusing position for different types of resist master disks. 
Seiko Epson Corporation
B G G
B23K G11B G11B
inventional additional inventional
Hideaki
Yamada