  We study modulation-free methods for producing sub-Doppler, dispersive line
shapes for laser stabilization near the potassium D2 transitions at 767 nm.
Polarization spectroscopy is performed and a comparison is made between the use
of a mirror or beam splitter for aligning the counter-propagating pump and
probe beams. Conventional magnetically-induced dichroism is found to suffer
from a small dispersion and large background offset. We therefore introduce a
modified scheme, using two spatially separated pump-probe beam pairs. Finally
we compare our results to methods using phase modulation and heterodyne
detection.
