The imaging technique of air-coupled vibrometry (ACV) is based on the modulation of the laser optical path length by the acoustic pressure of the sound wave in air. The theoretical consideration includes the analysis of acousto-optical phase modulation and the angular sensitivity of the ACV. The sensitivity of the ACV in detecting vibration velocity was estimated as ~1 mm/s and shown to reach maximum for the spatial acoustic component propagating normal to the laser beam. For higher-intensity ultrasound, the classical nonlinear effect of the second harmonic generation was measured in air. The ACV enables to visualize the nonlinear airborne field and to measure remotely the absolute values of particle velocities. The nonclassical nonlinear application includes a direct observation and quantification of the nonlinear air-coupled emission (NACE) from damaged areas in solid materials. The interpretation of the NACE patterns based on the theory of sound radiation is suggested.

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