one side of information carrying groove 14 than the other the light intensity distribution of reflected beam 16 on detector 10 becomes asymmetrical with respect to axis 40 the result is that the detector sections 41 and 43 on the first side of axis 40 will not detect the same amount of radiation as the detector sections 42 and 44 on the second side of axis 40 therefore the third signal sum and the fourth signal sum will not be equal for this reason when the third and fourth signal sums are differentially combined in operational amplifier 94 a tracking error signal on lead 32 will result fig5 b shows an enlarged view of optical disk 12 and circular information carrying grooves 14 also shown in fig5 b is a graphic illustration of the tracking error signal with respect to the lens position on the tracking axis 36 as shown the further the lens 18 is displaced from the proper tracking position along axis 36 the greater the magnitude of the tracking error signal as shown previously in fig1 once the focus error signal and tracking error signal are derived from the processing logic 28 and detector 10 they are fed to the focus actuator 34 and tracking actuator 38 respectively the actuators 34 and 38.