EMISSIVE LIGHT INSPECTION METHOD FOR OPTICAL PICKUP

摘要

PURPOSE:To enable the exact measurement of effective optical power to be used for recording/reproducing, and to execute following control operation without fail by detecting light to be emitted from an objective lens separately concerning a convergent light component to be condensed at a condensing point and another scattered light component. CONSTITUTION:When the optical output of an optical pickup is checked, namely, when the optical power to be emitted through an objective lens 4 to an optical information recording medium is checked, a photo-detector 10 is arranged in front and back of a condensing point 7 of the objective lens 4 and the effective optical power is measured. The photodetector 10 is composed of a convergent light receiving element 10a, which is arranged in a central part, and a scattered light receiving element 10b arranged around the element 10a. Then, respective detection output signals A and B are added by an adder 11 and the arithmetic of an output signal B/(A+B) is executed by a divider 12. The signal (A+B) expresses the whole power of the light to be emitted from the objective lens 4 and the signal B/(A+B) expresses the power ratio of scattered light to the emissive power from the objective lens 4.