We analyze the deflection of a probe beam because of pump-probe interaction in a high-absorbing thermal medium. We extend the existing theory by accounting for translation of a finite-width probe because of deflection within the nonlinear sample. We also provide expressions for the number of resolvable angles of the probe for possible applications of the setup as a beam deflector and study conditions for the maximization of the deflection angle and the resolution. We present experimental results obtained with a solution of chlorophyll in ethanol as the thermal medium.