An optical tracking

A.APPAREIL OPTICAL TRACKING. B.A WITH A REEL DRIVE 24 FIXED IN REAR ARM 23 WHICH BAND IS PARALLEL TO THE CURRENT PLAN AND ROTATION ARM ONE PAIR OF ELEMENTS 25A, 25B AIR GAPS A 26D, 27B FORMING MAGNETIC FIELDS. C.L'INVENTION APPLY ESPECIALLY TO OPTICAL DISC PLAYER.