Novel measurement of flying height and attitude using Michelson laser interferrometry

Head-medium spacing for magnetic disk storage is the most important parameter, which must be measured accurately down to the nanometer level. Thus far, light interference based on the homodgne technique have been apphed to spacing measurements throuah a glass disk instead of actual disks. This techniquo, however, have nearly reached ita limitation, since the spacing ha.: reduced M B much lesser degree than 1/4 0.. wavelength), the standard spacing used for calibration. To overcome this limitation due to the necessity ofcahbration. novel measurement of flying height and attitude is developed. The major advantagcs of this method are no necessity ofwilibrarion and applicability to in-situ measurement using actual heads and disks.