  We report on a high-resolution double-channel imaging method used to
synchronously map the intensity- and optical-frequency-distribution of a laser
beam in the plane orthogonal to the propagation direction. The synchronous
measurement allows us to show that the laser frequency is an inhomogeneous
distribution below threshold, but that it becomes homogeneous across the
fundamental Gaussian mode above threshold. The beam's tails deviations from the
Gaussian shape, however, are accompanied by sizeable fluctuations in the laser
wavelength, possibly deriving from manufacturing details and from the influence
of spontaneous emission in the very low intensity wings. In addition to the
synchronous spatial characterization, a temporal analysis at any given point in
the beam cross-section is carried out. Using this method, the beam homogeneity
and spatial shape, energy density, energy center and the defects-related
spectrum can also be extracted from these high-resolution pictures.
