| 摘要 |
PURPOSE: To improve a converged spot shape by varying a width of a light shielding band performing super resolution so as to become an optimum width. CONSTITUTION: A collimator lens 32, a light shielding means 33, a beam splitter 34 and a condenser lens 35 are arranged in this order in the outgoing direction of a semiconductor laser 31, and the light shielding means 33 is a rectangular plane long in the Y axis direction of a co-ordinate axis around an optical axis 36, and is constituted so as to be turned around the Y axis. A recording medium 37 such as a disk type or a card type is arranged on the focal position of the condenser lens 35, and an information track 38 is formed on the recording medium 37. A lens 39 is arranged in the reflective direction of the beam splitter 34 by viewing from the propagating direction of a laser beam outgoing from the semiconductor laser 31, and a bisected photodetector 40 is provided on the front side or the rear side of the focal distance position of the lens 39. Respective output signals from the photodetector 40 are connected to a differential amplifier 41 and an adder 42, and the output signal of the adder 42 is connected to a laser drive circuit 43, and a drive current I from the circuit 43 is injected into the semiconductor 31. |
