摘要 |
In an optical memory device, such as an optical video disk, an injection laser is used as the source of the light, as the detector of the light reflected from the memory element and as the detector for controlling the proper focus of the light on the memory element. The light reflected from the memory element is fed back into the injection laser and variations in certain characteristics of the injection laser, such as the optical output at constant current, the electrical current through the laser at constant voltage and the voltage drop across the laser at constant current, are used to read the memory device and to maintain the focus. |