Measurement of Orientation of Magnetic Particles in a Recording Disk Using Polarized Microscopy
Original Publication Date: 1985-Jul-01
Included in the Prior Art Database: 2005-Feb-18
The anisotropic nature of the acicular gamma iron oxide particle used for the particulate-coated magnetic recording disk is highly suitable for crossed field polarized microscopy analysis. Recent experimental evidence has demonstrated that particle orientation can be optically measured and correlated to magnetic orientation ratio and signal-to- noise ratio measurements. The optical measurement is the intensity of reflected light from the coated disk at the maximum and minimum extinction values using a microscope equipped with an adjustable polarizer, analyzer and photometer. The system includes a low-power objective lens coupled with a crossed polarizing filter adjustable for both 0Œ and 45Œ angles of rotation.