  Wide field-of-view imaging of fast processes in a microscope requires high
light intensities motivating the use of lasers as light sources. However, due
to their long spatial coherence length lasers are inappropriate for such
applications as they produce coherent noise and parasitic reflections, such as
speckle, degrading image quality. Therefore, we provide a step-by-step guide
for constructing a speckle-free and high contrast laser illumination setup
using a rotating ground glass diffuser driven by a stepper motor. The setup is
easy to build, cheap and allows a significant light throughput of 48 %, which
is 40 % higher in comparison to a single lens collector commonly used in
reported setups. This is achieved by using only one objective to collect the
scattered light from the ground glass diffuser. We validate the stability and
performance of our setup in terms of image quality, motor-induced vibrations
and light throughput. To highlight the latter, we record Brownian motion of
micro-particles using a 100x oil immersion objective and a high-speed camera
operating at 2 000 Hz with a laser output power of only 22 mW. Moreover, by
reducing the objective magnification to 50x sampling rates up to 10 000 Hz are
realized. To help readers with basic or advanced optics knowledge realizing
this setup we provide; a full component list, 3D-printing CAD files, setup
protocol, and the code for running the stepper motor.
