Laser heterodyne cross-polarized technique for inspection of magnetic disks

• Published in: Optics communications 2006-04, Vol.260 (2), p.372-382
• Main Authors: Protopopov, Vladimir V., Cho, Sunghoon, Kwon, Youngkun, Lee, Sukwon, Kim, Hyuk
• Format: Article
• Language: English
• Subjects: Atomic and molecular physics; Condensed matter: electronic structure, electrical, magnetic, and optical properties; Exact sciences and technology; Heterodyning; Kerr effect; Magnetic disk; Magnetooptical effects; Molecular properties and interactions with photons; Optical activity and dichroism; magnetooptical and electrooptical spectra; Optical properties and condensed-matter spectroscopy and other interactions of matter with particles and radiation; Optical properties of bulk materials and thin films; Other magnetooptical and electrooptical effects; Physics; Polarization; Zeeman laser
• ISSN: 0030-4018; 1873-0310
• DOI: 10.1016/j.optcom.2005.10.062

A new optical technique for observation of service magnetic tracks on magnetic disks is developed. Weak depolarization of the probe beam due to longitudinal magneto-optical Kerr effect is detected by means of heterodyne mixing of the two cross-polarized and frequency shifted waves generated by Zeeman-type laser. In comparison with the traditional homodyne method the proposed technique has better sensitivity and spatial resolution. Experimental results obtained with standard sample magnetic disks showed the signal-to-noise ratio of about 10, and the spatial resolution of about 30μm. A possibility of the phase-contrast super-resolution is discussed.