| 摘要 |
PROBLEM TO BE SOLVED: To make it possible to reproduce an optical disk which is partly metallized but partly not metallized by using a laser reader having an automatic power controller having a wide dynamic range with fast operation. SOLUTION: An optical disk 11 has an area A having a part which has the metallized part of a metallized 50 area B and is removed or damaged. It has a variable power semiconductor laser 100 which generates a continuous wave laser beam of 780 nanometer of variable output 120 of a range of about 0.3 to 20mW of output. To achieve the 20mW of power level, a laser power driver 115 is used, and the power of the laser 100 is varied by a control signal 130 applied to the control terminal 110 of the driver 115 for driving the laser 100. The generated beam 120 is converted to parallel beams via a beam splitter 140 and then collimator lens 150, incident to an objective lens 160 to form a focus on a concave surface 170. |
