  We present a technique for mapping the complete 3D spatial intensity profile
of a laser beam from its fluorescence in an atomic vapour. We propagate shaped
light through a rubidium vapour cell and record the resonant scattering from
the side. From a single measurement we obtain a camera limited resolution of
200 x 200 transverse points and 659 longitudinal points. In constrast to
invasive methods in which the camera is placed in the beam path, our method is
capable of measuring patterns formed by counterpropagating laser beams. It has
high resolution in all 3 dimensions, is fast and can be completely automated.
The technique has applications in areas which require complex beam shapes, such
as optical tweezers, atom trapping and pattern formation.
