  We analyze and compare the angular deviations for an optical beam reflected
by and transmitted through a dielectric triangular prism. The analytic
expressions derived for the angular deviations hold for arbitrary incidence
angles. For incidence approaching the internal and external Brewster angles,
the angular deviations transverse magnetic waves present the same behavior
leading to the well-known giant Goos-Haenchen angular shift. For incidence near
the critical angle a new region of large shift is seen both for transverse
magnetic and transverse electric waves. While a direct measuring procedure is
better in the vicinity of the Brewster region, a weak measurement breaks off
the giant Goos-Haenchen effect, preserving the amplification in the critical
region. We discuss under which conditions it is possible to optimize the
amplification and we also determine when a weak measurement is preferred to a
direct measuring procedure.
