MEASURING INSTRUMENT FOR FLOATING QUANTITY

PURPOSE:To reduce the measuring time by increasing/decreasing the number of revolutions of a disk monotonously and continuously between low and high speeds to change it and applying waveform processing to the number of revolution output proportional to the number of revolutions and the interference luminous quantity correspondingly to measure the floating of a head slider. CONSTITUTION:The number of revolutions of a servo motor 12 is changed continuously to drive a spindle 13 from a low to a high speed at once. A photodetection section 23 detects interference light caused between a disk 11 and the head slider 21 during the acceleration of the spindle 13 to send a voltage change to a waveform storage section 24. Simultaneously, a DC output proportional to the number of revolutions of the spindle 13 being accelerated is sent also to the waveform storage section 24, which stores the waveform of the output of the photodetector 23 and the timewise change in the DC output. When the number of revolutions of the spindle 13 is changed, the interference luminous quantity caused in the head slider 21 is changed while following up said change, a computer 16 applies waveform processing based on the stored waveform to measure the floating quantity of the head slider 21.