Experimental Study on Magneto-Optical Disk Exerciser with the Laser Diode and Amorphous Magnetic Thin Films

Abstract

Amorphous TbFe and GdTbFe films as magneto-optical memory media are prepared by means of sputtering on a glass disk with a diameter of 115 mm. With these films, writing and reading of digital information are successfully accomplished using a semiconducting laser diode of AlGaAs. Thus the track density reaches easily as high as 200 lines/mm. A fine track access mechanism is proposed, where a moving coil actuater is driven by an analog signal obtained from differential reading of two spots. The method of fine focusing is also described in detail, where cylindrical beam-shaping and four element PIN diode are used.