Direct Visualization of Molecularly Thin Lubricant Films on Magnetic Disks by Ellipsometric Microscopy With a White Light Source

We demonstrated the direct visualization of molecularly thin lubricant films on magnetic disks with a thickness resolution of 0.1 nm by using an ellipsometric microscope with a white light source. It was able to reduce the optical interference noise that arises in conventional laser-based ellipsometric microscopes and to provide a larger SNR by a factor of about 6 compared to a laser-based ellipsometric microscope. The wavelength width should be given first priority in designing a white-light-source ellipsometric microscope, and the width should be determined after considering the required coherence length and thickness resolution. Theoretical calculations indicate that a wavelength width of less than 10 nm can provide a thickness resolution of 0.1 nm. A white-light-source ellipsometric microscope can provide real-time visualization of a molecularly thin lubricant film with a thickness resolution of 0.1 nm, which is useful in investigating the kinetic behavior of molecularly thin lubricant films on magnetic disks.