In this paper the design of a large angular aperture acousto-optic tunable filter (AOTF) using TeO2 crystals is described. A new crystal orientation with θα= 100° and θi, =23.4° is proposed. It has been proved in the experiments that this AOTF meets Hi e exact condition of tangent momentum match. The measured tuning relation is in good agreement with theoretical calculations and the spectral resolution has been improved by nearly 10A. After compensation, the change in deflection angle is decreased to ±0.06°.