  We present methods and results of the testing of an inexpensive home-made
diffraction limited lens system, the design of which was proposed in a recent
paper and which has since been used (with slight alterations) by several
research groups. Our system will be used for both: focussing a collimated laser
beam at a wavelength of lambda=830 nm down to a narrow spot and for collimating
fluorescence light (lambda=780 nm) emitted from rubidium atoms captured in this
spot. Useful tests for lens systems include the use of ray tracing software,
shear-wave interferometers, the imaging of test charts and of polystyrene beads
of a very small size. We present these methods and show how conclusions can be
drawn for the design under test.
