  In this paper we describe the technical implementation of pump-probe
cathodoluminescence microscopy (PP-CL), a novel technique for studying
ultrafast dynamics in materials using combined excitation of electron and laser
pulses. The PP-CL setup is based on a commercial scanning electron microscope
combined with a femtosecond laser. Here we discuss the design, technical
details, and characterization of the PP-CL setup. The luminescence emitted by
the sample (either photoluminescence, cathodoluminescence or a combination of
both) can be analyzed in terms of spectrum, temporal statistics, and
frequency-modulated intensity (lock-in detection). The laser spot on the sample
is characterized by analyzing the changes in the secondary electron signal on a
GaN substrate, from which we extract a laser spot size in the $\mu m$ range.
While this method ensures spatial overlap of laser and electron pulses on the
sample, temporal alignment is achieved using time-correlated measurements of
photoluminescence and cathodoluminescence. We also discuss some considerations
to take into account when designing a PP-CL experiment, regarding temporal and
spatial resolution. This paper provides a detailed reference for the
development of any PP-CL microscope.
