MEASURING METHOD FOR BEAM SPOT DIAMETER OF OPTICAL HEAD FOR OPTICAL DISK

摘要

PURPOSE:To easily and accurately take a measurement by detecting time intervals of time when a measurement edge provided to a rotary substrate passes through a beam spot and measuring the diameter of the beam spot from the time intervals and the moving speed of the measurement edge. CONSTITUTION:The rotary substrate 1 is irradiated with the light beam so that the beam spot is formed on the plate surface of the rotary substrate 1. Then when the rotary substrate 1 is rotated at a constant speed, intervals of time when the measurement edge 4a passes through the beam spot are detected optically and the beam spot diameter is found from the time intervals and the moving speed of the measurement edge. Thus, the beam spot diameter of the optical head for the optical disk is easily and accurately measured with good reproducibility.