Patent ID: 7359294

Claim:
An optical scanning device for scanning an optical record carrier by means of a radiation beam, said optical scanning device comprising: an optical system for directing said radiation beam to an information layer of the optical record carrier, said optical system comprising means for focusing at least a main part of said radiation beam to a spot on said information layer, and a redirecting structure for redirecting a second part of said radiation beam other than said main part along a path to said information layer different from a path of said main part of said radiation beam, said optical system further receiving and directing a reflected radiation beam, reflected from said information layer, inclusive of a reflected main part corresponding to said main part of said radiation beam and a reflected second part corresponding to said second part of said radiation beam; and a detection system including an information signal detector for receiving said reflected main part from said optical system for detecting an information signal therein, and a position sensitive detector collocated with said information signal detector for receiving said reflected second part from said optical system, said position sensitive detector detecting a position of the reflected second part of the reflected radiation beam, wherein the redirecting structure comprises a first portion for redirecting the second part of the radiation beam when traveling towards the record carrier, and a second portion for redirecting the reflected second part of the reflected radiation beam after reflection from the record carrier, wherein the optical system comprises a reflective portion for reflecting a part of the radiation beam such that the reflected beam part follows a path which is different to a path followed by the main part of the radiation beam, and wherein the position sensitive detector detects a position of the reflected beam part.