RECORDER

摘要

In the recording apparatus of the invention, a series of operations are performed including locating a PD 81 at a predetermined position on an optical base, stopping the rotation of a resist master disk 110, activating a focusing laser 73, and optimumly positioning a head 77 by means of a head slider control circuit 101. The resist master disk 110 is then starts to rotate, followed by starting of a focus servo circuit 103. A focus fine adjust circuit 99 effects a fine movement of the PD 81 to the left or right by an amount which corresponds to predicted optimum focusing position data. Error signal indicative of the difference between voltage signals derived from two output terminals of the PD 81 varies partly because of a waving of the disk 110 due to rotation and partly because of the fine movement of the PD 81. A differential amplifier 103a serves to cause a recording lens 77a to move up or down by an amount of several mu m, so as to nullify the error signal. Numerical information displayed on a digital display unit 93 is compared with the above-mentioned focusing position data and, when the numerical information coincides with the focusing position data, the above-mentioned focusing data is used as an optimum focusing position data for the purpose of initial setting of the optimum focusing position. When such coincidence is not obtained, updating of the data is performed by storing the numerical information as the optimum focusing position data. The use of optimum focusing position data in the form of numerical values permits easy initial setting of the optimum focusing position for each of different types of resist master disk.