| 摘要 |
PURPOSE:To improve resolution by dividing the photodetection surface of a photodetector for information reproduction and storing a positive or negative corresponding weight coefficient, and detecting binary information in the sum or difference signal of signals obtained by multiplying respective photodetection outputs by the weight coefficients. CONSTITUTION:For example, a laser beam from a light emitting element is projected on a medium where optical information is recorded and its reflected light is detected by the photodetector 81 for information reproduction. The element 81 is divided concentrically into N parts, which output voltages proportional to their quantities of light to mutually independent output lines 9a-9n. When the irradiated beam has a distribution of intensity like a Gaussian distribution, a weight function based upon the distance from the center of the photodetector is stored and inputted to an operational amplifier 11. The weight function is set by resistances 10-10n having relative sensitivity with elements 81a-81n. Signals multiplied by weight coefficients are summed up by the amplifier 11 to improve the resolution even when a laser of relatively thick beam size, detecting binary information. |
