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A large thallium arsenic selenide, Tl 3 AsSe 3 (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 acousto-optic tunable filter (AOTF) in a 12.0° 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 CO 2 laser at 10.6 μm, 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 8 cm −1 , and a peak response at 13.25 MHz. The measurements were performed at lower powers, and scaled to an efficiency of 27% at 200 mW/cm 2 . By comparison, the theory gives 33.5% at 200 mW/cm 2 of acoustic power. If a power of 300 mW/cm 2 is applied, theoretically 51% efficiency will be achieved at 10 μm. |
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