| 摘要 |
PURPOSE:To accurately measure the levitating amount of a head, by laminating a transparent thin film on a transparent disk disposed in opposing relation to the head, the film having a refractive index different from that of the disk, and setting the interference between reflected light rays in the second-order interference region or higher. CONSTITUTION:A transparent thin fim 3 of, for example, MgF2, is formed on the lower surface 11 of a transparent (glass) disk 1. The reflectance of the reflected light b' obtained when an incident light I vertically enters the film 3 is controlled such as to be 1/3 of the reflectance of the reflected light a'. The interference between the light a' and the light c' with respect to the vertically incident white light I shows a hue change corresponding to the second-order interference region with a Newtonian scale of 0.28-0.41(mum). Therefore, the levitating amount of the head can be accurately measured even in a low levitating region of 0.23mum or smaller. |
