INTERFEROMETRIC SPACING MEASUREMENTS OF THE BERNOULLI HEAD DISK INTERFACE

Head-to-disk spacing in a flexible disk drive (Bernoulli technology) is measured interferometrically using monochromatic light in conjunction with a grey level interpolation scheme. Measurements in the center region of a Bernoulli head indicate that the minimum head/disk separation is less than 50nm (2-mu-in), suggesting that asperity contacts occur in the area of closest approach. The spacing distribution of a typical Bernoulli head is reported, as well as a parameter study of spacing as a function of rotational speed.