PHY17 Acousto-Optical Modulation of Standing Ultrasonic Waves

 Acousto-Optical Modulation of Standing Ultrasonic Waves Investigation of the acousto-optical effect of amplitude and phase modulation of light diffracted by a standing ultrasonic wave The acousto-optical effect of amplitude and phase modulation of light diffracted by a standing ultrasonic wave is investigated. The effect is used to determine the speed of sound in water. Keywords: acousto-optical effect, standing ultrasonic wave, sound wavelength, diffraction, optical grating, grating constant, amplitude modulation, phase shift According to the Debye-Sears effect (PHY11), light is diffracted by a standing or moving ultrasonic wave in a liquid or solid. The diffraction maxima generated by diffraction by a standing ultrasonic wave are amplitude modulated, with a phase shift of 180° occurring between the 0th and nth order maximum. This effect is used in acousto-optical modulators (AOM). Amplitude modulation and phase shift can be detected using photodiodes and an oscilloscope. A change in