MEASURING METHOD OF DISTANCE BETWEEN GAP OF MAGNETIC HEADS

摘要

PURPOSE:To enable to measure the distance of gap between a plurality of magnetic heads with high accuracy, by diffraction pattern of coherent light. CONSTITUTION:The reference piece 15 having two ridgelines 14 having the gap slightly greater than the gap is located to the magnetic head assembly, the slit 19 is formed among the ridgeline 14 of the reference piece 15 and the ridgeline 18 with the gap opposing surface 16 of magnetic head and the chip side surface 17, and the coherent light, e.g. laser beam 21 is incident to the slit 19 with flat mirrors 22 and 23. On the photodetecting plane of the photodetector arrays 24, 25 located at the position apart from the slit 19 by the size D, the diffraction stripe 26 of 0 order and the diffraction stripe 27 of the 1st order are caused, and the distances X1 and X2 of slit are as expressed in equation I by taking the stripe distances of 0 and the 1st order as d1 and d2 (where; lambda is the wavelength of laser light source and Dd1.d2). Taking the distance of the ridgelines 14 of the reference piece 15 as (a), the gap distance of two megnetic heads is as expressed as equation II, and the distance can be calculated with the stripe distances d1 and d2 measured with the photodetector arrays 24 and 25.