Forming non-diffracting beams using a 2D matrix phased array probe

This paper presents a simple way to form non-diffracting narrow beams, also called bessel beams, with phased arrays. Normally non-diffracting beams are generated by using axiconi-cal lenses. The axiconical lens is simulated by phased array ultrasonic technique using a delay time distribution that is chosen according to the sound path in axiconical lenses. The phased array probe is a 2D matrix array with 121 elements. Each element is driven by another delay time. The delay times which are usually used for this probe to focus in different depth of the material are distributed spherical-ly over the area of the probe. To form a non-diffracting beam the distribution of the time delays is linearly increasing to the center of the probe. In the paper the results of the simulation are given. By varying the parameters in the simulation the best setting is chosen. With this an experiment is done and the expe-rimental results are compared to the simulation results. Considerations on the best probe to form non-diffracting beams with phased array are described.