COMPUTER-SIMULATIONS OF EFFECTS OF DISK TILT AND LENS TILT ON PUSH-PULL TRACKING ERROR SIGNAL IN AN OPTICAL DISK-DRIVE

We quantify the effects of disk tilt and objective lens tilt on the pu sh-pull tracking error signal of an optical disk data storage system. For a grooved disk, such as a recordable compact disk that operates at a laser wavelength of lambda, it is found that disk tilt produces a t racking offset of 0.05 lambda per degree of tilt, whereas objective le ns tilt produces an offset of 0.012 lambda per degree of tilt. The amp litude of the tracking error signal decreases by 2.5% at the disk tilt angle of 0.3 degrees and by 5% at the objective lens tilt of 0.3 degr ees. We achieved these simulations with the computer program DIFFRACT, which performs a combination of diffraction and ray-tracing calculati ons through the entire optical path, from the light source to the dete ctors. (C) 1997 Optical Society of America.