Two-wavelength laser pick-up head for a DVD

摘要

A two-wavelength laser pick-up head used for accessing DVD, CD, CD-R and CD-E systems. The two-wavelength laser pick-up head includes a shorter wavelength laser optical path for reading the data from a DVD system, and a longer wavelength laser optical path for reading the data from a CD or CD-R system. The above two optical paths use the same collimator and the same objective lens. There is a compensator lens which is used in the longer wavelength laser optical path for correcting the spherical aberration due to the thick substrate of the CD or CD-R.