Amplification Characteristics of Fresnel Zone Plate Acoustic Lens

Abstract

This paper aims to determine the effects of a Fresnel Zone Plate on the intensity of sound waves upon their interaction. To observe these effects, a prototype Even Fresnel Zone Plate, composed of four concentric rings, was made from an acrylic sheet with the dimensions 60.0cm x n60.0cm x 3.13mm. The exact dimensions of the prototype were calculated using the selected focal length and working frequency in order to optimize for the constructive interference of sound waves. After a sound wave at the selected frequency is produced, a small region of highly amplified sound is formed and studied. It was discovered that the amplification of sound waves is highly dependent on the frequency of sound, as well as the location at which the sound intensity level is measured.