  We describe a novel approach for generating light beams that carry orbital
angular momentum (OAM) by means of total internal reflection in an isotropic
medium. A continuous space-varying cylindrically symmetric reflector, in the
form of \textit{two glued hollow axicons}, is used to introduce a nonuniform
rotation of polarisation into a linearly polarised input beam. This device acts
as a full spin-to-orbital angular momentum convertor. It functions by switching
the helicity of the incoming beam's polarisation, and by conservation of total
angular momentum thereby generates a well-defined value of OAM. Our device is
broadband, since the phase shift due to total internal reflection is nearly
independent of wavelength. We verify the broad-band behaviour by measuring the
conversion efficiency of the device for three different wavelengths
corresponding to the RGB colours, red, green and blue. An average conversion
efficiency of $95\%$ for these three different wavelengths is observed. %,
which confirms its wavelength independence. This device may be used to generate
a white vector vortex beam, as we show, and may find applications in imaging
from micro- to astronomical systems where a white vortex beam is needed.
