The effect of detector distance and beam width in acousto-optical beam deflection probing in air

We investigate the effect of detector distance and beam width in acousto-optic beam deflection probing in air. The study investigates pure refraction regime (beam width⪡ acoustic wavelength). We find that in this regime the increase in beam width can significantly increase the detected signal up to 8 folds higher than previous detection geometries—while the detector distance has a less noticeable effect. Theoretical results are assessed through an experiment with a commercially available ultrasonic transducer. This investigation provides detailed theoretical approaches and quantitative experimental characterization that can be used for numerous applications requiring beam deflection probing in air. ► Analytical and experimental study of low frequency airborne acousto-optical beam bending. ► Prediction of the effect of acoustic wavelength on beam deflection in theory. ► Study and experimentation of non-acoustic parameters: affected region distance and beam width. ► Recognition of the effect of the beam width parameter as a dominant effect in deflection signal. ► For a focused beam, increase in beam width can increase the deflection signal up to 8 times.