An Ultrasonic grating is a type of diffraction grating produced by an ultrasonic wave. An ultrasonic wave is a sound wave having a frequency greater than 20 kHz. Because of the very small wavelength of ultrasonic waves compared to X-rays they have considerable penetrating power. The human ear can not recognize ultrasonic waves, but animals such as bats and dogs can easily sense the ultrasonic wave. It is produced by the phenomena of the Piezo-electric effect and magnetostriction.
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