  In conventional Kerr- and Faraday microscopy the sample is illuminated with
plane-polarised light and a magnetic domain contrast is generated by an
analyser making use of the Kerr- or Faraday rotation. In this paper we
demonstrate possibilities of analyser-free magneto-optical microscopy based on
magnetisation-dependent intensity modulations of the light: (i) The transverse
Kerr effect can be applied for in-plane magnetised material, demonstrated for
an FeSi sheet. (ii) Illuminating the same sample with circularly polarised
light leads to a domain contrast with a different symmetry as the conventional
Kerr contrast. (iii) Circular polarisation can also be used for perpendicularly
magnetised material, demonstrated for a garnet film and an ultrathin CoFeB
film. (iv) Plane-polarised light at a specific angle can be employed for both,
in-plane and perpendicular media. (v) Perpendicular light incidence leads to a
domain contrast on in-plane materials that is quadratic in the magnetisation
and to a domain boundary contrast. (vi) Domain contrast can even be obtained
without polariser. In cases (ii) and (iii), the contrasts are generated by MCD
(Magnetic Circular Dichroism), i.e. by the differential absorption of left and
right circularly polarised light, induced by magnetization components along the
direction of light propagation. In case (v) the contrast is caused by MLD
(Magnetic Linear Dichroism), i.e. by the differential absorption of linearly
polarised light, induced by magnetisation components transverse to the
propagation direction. The domain boundary contrast is due to the
magneto-optical gradient effect. An explanation of these contrast phenomena is
provided in terms of Maxwell-Fresnel theory.
