| 摘要 |
PURPOSE:To enable the measurement of <=0.1mum spacing by using light interference with high accuracy by expanding an optical interference distance with plural transparent bodies which have different refractive indices and are in tight contact with each other. CONSTITUTION:A magnetic head 1 is afloat from a transparent disc 2 at a prescribed floating spacing. The disc 2 is of the 3-layered construction wherein a TiO2 film 11 of the 2nd transparent material layer is vapor-deposited at 50nm on a white plate glass substrate 10 of the 1st transparent body and further an SiO2 film 12 of the 3rd transparent material layer is vapor-deposited at 200nm on the surface thereof. When the head 1 is floated at a periferal speed of 46m/S on an ordinary glass disc, there is 0.21mum floating spacing and when the head 2 is floated on the 3-layered glass disc 2, the floating spacing is 0.45mum, that is, the interference distance is prolonged by 0.24mum. If the peripheral speed is assumed to be 16m/S, the floating spacing indicates 0.32mum, and there is always 0.24mum difference from the calculated value 0.08mum, and the measurement of <=0.1mum spacing is made possible with the accuracy similar to the accuracy in conventional measurement. |
