The ratio of neutral Higgs field vacuum expectation values, tan beta, is one
of the most important parameters to determine in type-II Two-Higgs Doublet
Models (2HDM), specifically the Minimal Supersymmetric Standard Model (MSSM).
Assuming the energies and integrated luminosity of a future high energy e^+e^-
linear collider of sqrt{s}=500, 800, 1000, and 1500 GeV and L=1 ab^{-1} we show
that associated t H^+/- production in gamma gamma collisions can be used to
make an accurate determination of tan beta for low and high tan beta by
precision measurements of the gamma gamma -> H^+/- t + X cross section.Comment: 7 pages, 11 figures, uses REVTEX
