Optical Head With Switchable Diameter of the Radiation Spot on the Radiation Detector

摘要

In an optical scanning device ( 10 ) capable of scanning an information plane of an optical record carrier ( 5 ) of different types such as BD, DVD and CD, the diameter of the radiation spot on the detector ( 7 ) is dependent on the numerical aperture of the objective system ( 4 ) that is used for scanning the record carrier An optimal design of the optical detection system for scanning a BD, result in a small radiation spot for the other types such as DVD and CD. By implementing an optical element ( 13 ) that increases the diameter of the radiation spot in the situation a DVD or CD is scanned, the influence of stray light is reduced and the tracking signals are improved