  THz-spectroscopy is an attractive imaging tool for scientific research,
especially in life science, offering non-destructive interaction with matter
due to its low photon energies. However, wavelengths above $100{\mu}m$
principally limit its spatial resolution in the far-field by diffraction to
this regime, making it not sufficient to image biological cells in the
micrometer scale. Therefore, super-resolution imaging techniques are required
to overcome this restriction. Near-field-imaging using spintronic emitters
offers the most feasible approach because of its simplicity and potential for
wide-ranging applications. In our study, we investigate THz-radiation generated
by fs-laser-pulses in CoFeB/Pt heterostructures, based on spin currents,
detected by commercial LT-GaAs Auston switches. The spatial resolution is
evaluated applying a 2D scanning technique with motorized stages allowing
scanning steps in the sub-micrometer range. By applying near-field imaging we
can increase the spatial resolution to the dimensions of the laser spot size in
the micrometer scale. For this purpose, the spintronic emitter is directly
evaporated on a gold test pattern separated by a 300 nm spacer layer. Moving
these structures with respect to the femtosecond laser spot which generates the
THz radiation allows for resolution determination using the knife-edge method.
We observe a full-width half-maximum THz beam diameter of $4.9(4){\mu}$m at 1
THz. The possibility to deposit spintronic emitter heterostructures on simple
glass substrates makes them an interesting candidate for near-field imaging for
a large number of applications.
