Patent ID: 7209413

Claim:
An optical scanning device for scanning an information layer of an optical record carrier, the device including: a rotary arm ( 2 ; 102 ; 202 ; 302 ; 402 ; 502 ) which is arranged to swing about a rotation axis (CR) to alter an angular position of the rotary arm about the rotation axis; a detector arrangement ( 10 ) arranged separate from the rotary arm ( 2 ; 102 ; 202 ; 302 ; 402 ; 502 ) for detecting a radiation beam spot, the radiation beam spot ( 40 ; 140 ; 240 ; 340 ; 440 ; 540 ) having an angular disposition; a first reflective surface ( 4 ; 104 ; 204 ; 304 ; 404 ; 504 ) attached to the rotary arm ( 2 ; 102 ; 202 ; 302 ; 402 ; 502 ); a second reflective surface ( 6 ; 106 ; 206 ; 306 ; 406 ; 506 ) attached to the rotary arm ( 2 ; 102 ; 302 ; 402 ; 502 ); a first light path (LP 1 ; LP 101 ; LP 201 ; LP 301 ; LP 401 ; LP 501 ) running from a location on the record carrier to said first reflective surface; a second light path (LP 2 ; LP 202 ; LP 302 ; LP 402 ; LP 502 ) running from said first reflective surface to said second reflective surface; a third light path (LP 3 ; LP 103 ; LP 203 ; LP 303 ; LP 403 ; LP 503 ) running from said second reflective surface to said detector arrangement ( 10 ), characterized in that said rotary arm includes at least one optical inversion element ( 52 ; 54 ; 56 ; 58 ; 64 ; 66 ) arranged such that a dependence between variation of the angular position of the rotary arm and variation of the angular disposition of the radiation beam spot is reduced.