abstract:Optical discs with the exception of the DVD-RAM have their data encoded on a single spiral, or a groove, which covers the surface of the disc. In the case of recordable media, this spiral contains a slight sinusoidal deviation from a perfect spiral.
It is posed that angular air-hammer self-excitedvibrationand halffrequencywobble self-excited vibration are two reasons for resulting angular wobble self-excited vibration forgasfilmfaceseals.