Measuring Tangential Tilt of a Rotating Disk
Original Publication Date: 1987-Feb-01
Included in the Prior Art Database: 2005-Jan-31
Tilt of a rotating disk is an important parameter to know for rotating signal-storing disks. The use of a laser vibrometer (VM), (a machine that generates a voltage n(z) proportional to the velocity of a vibrating surface normal to the laser beam) allows one to measure tangential tilt of the disk during its rotation by capturing the axial runout signal from the VM and displaying it on a digital oscilloscope. One can determine the tangential tilt profile by multiplying the VM output waveform by an appropriate value. Given an axial runout signal shown in the figure, the tilt angle, r, is a function of the slope of the waveform ZS by the following relations: (Image Omitted) where z is axial displacement and s is angular displacement.