| 摘要 |
PURPOSE:To constitute an accurate tracking control mechanism simply by using as a light emission source a semiconductor laser device of lamination structure which generates three laser beams at the same time. CONSTITUTION:On an n type GaAs substrate (a), n type clad layers (b1)-(b4), n type active layers C1-C3, and an n type GaAs layer (d) are formed successively by capital crystal growth, and zinc is diffused from part of the layer (d) to the layer (b1) to make part of each layer into a p type area; and a couple of electrodes (e) and (f) are formed in the n type and p type areas of the layer (d), which is removed between the electrodes. Three laser beams generated by the semiconductor laser device 1 constituted as mentioned above are passed through a beam splitters 2, a 2/4-wavelength plate 3, and an objective lens 4 to illuminate tracks on a disk record D, and its reflected light is processed by photoelectric transducing 5 to input the photoelectric transducing output of the tracking beam to a tracking circuit 6, thereby displacing an objective lens holder 7 in the widthwise direction of the tracks. |
