Selective sensitivity in Kerr microscopy

TL;DR

This paper introduces a novel Kerr microscopy technique that uses synchronized LED illumination for real-time contrast separation and enhanced sensitivity, enabling detailed magnetic domain imaging with minimal parasitic effects.

Contribution

A new contrast separation method in Kerr microscopy using synchronized LED illumination, improving real-time imaging and sensitivity over conventional setups.

Findings

Simultaneous orthogonal in-plane sensitivity images at real-time.

Doubling of in-plane domain contrast.

Sensitivity to Kerr rotations as low as 0.6 millidegrees.

Abstract

A new technique for contrast separation in wide-field magneto-optical Kerr microscopy is introduced. Utilizing the light from eight light emitting diodes, guided to the microscope by glass fibers and being switched synchronously with the camera exposure, domain images with orthogonal in-plane sensitivity can be displayed simultaneously at real-time and images with pure in-plane or polar contrast can be obtained. The benefit of this new method of contrast separation is demonstrated for permalloy films, a NdFeB sinter magnet, and a cobalt crystal. Moreover, the new technique is shown to strongly enhance the sensitivity of Kerr microscopy by eliminating parasitic contrast contributions occurring in conventional setups. A doubling of the in-plane domain contrast and a sensitivity to Kerr rotations as low as 0.6~mdeg is demonstrated