Optical pickup astigmatism measuring method, optical pickup astigmatism adjusting method, and optical pickup astigmatism measuring system

摘要

It is an object of the present invention to provide an optical pickup astigmatism adjusting method capable of easily correcting an astigmatism even if the spot shape of a light beam converged on an optical disc is not a true circle. An optical pickup astigmatism adjusting system of the present invention finds an inter-focal distance L0 between a focal position where a light beam is converged in RAD direction and another focal position where a light beam is converged in TAN direction, and a further inter-focal distance L45 between a focal position where a light beam is converged in a direction inclined 45 degrees from RAD direction and another focal position where a light beam is converged in a direction inclined 45 degrees from TAN direction, thereby measuring an astigmatism in accordance with the inter-focal distances L0 and L45. Then, an installation angle of a reflection mirror is adjusted in accordance with the inter-focal distances L0 and L45, thus correcting the astigmatism.