A large thallium arsenic selenide, Tl3AsSe3 (TAS) crystal was grown by the Bridgman method for acousto-optic imaging application. An as-grown 38 mm diameter crystal was cut, polished and fabricated into 4.5 cm long acoustooptic tunable filter (AOTF) in a 12.0 degrees orientation of the transducer to the c-axis to achieve the power and resolution requirements. The fabricated AOTF was tested and measurements were obtained using a waveguide CO2 laser at 10.6 mum, where the beam was attenuated by diffuse reflection off a rough target placed about 2 m from the AOTF. The spectral response showed that the curve basically follows the predicted sinc(2) pattern, with a FWHM resolution of 8cm(-1), and a peak response at 13.25 MHz. The measurements were performed at lower powers, and scaled to an efficiency of 27% at 200mW/cm(2). By comparison, the theory gives 33.5% at 200mW/cm(2) of acoustic power. If a power of 300 mW/cm(2) is applied, theoretically 51% efficiency will be achieved at 10 mum.