Focal translation by frequency shift in free space

Citation
Hc. Song et al., Focal translation by frequency shift in free space, IEEE ULTRAS, 47(3), 2000, pp. 687-695
Citations number
12
Categorie Soggetti
Optics & Acoustics
Journal title
IEEE TRANSACTIONS ON ULTRASONICS FERROELECTRICS AND FREQUENCY CONTROL
ISSN journal
08853010 → ACNP
Volume
47
Issue
3
Year of publication
2000
Pages
687 - 695
Database
ISI
SICI code
0885-3010(200005)47:3<687:FTBFSI>2.0.ZU;2-N
Abstract
Variable focusing in range from a transmit array can be accomplished by a f requency shift in an acoustic waveguide [1]. In this paper, a general algor ithm is derived in free space that can move the focal spot of a linear tran smit array both transversely and horizontally. In particular, for variable range focusing, the prescribed frequency shift is the same for all elements of the array, whereas, for transverse focal shifts, the frequency shift va ries with element location in the array. The method described in this paper is especially suitable for varying the location of the focal spot of a tim e-reversal mirror in the presence of an aberrating layer in that no knowled ge of the medium properties is necessary. Simulation results demonstrating the proposed method are presented in comparison with those from a conventio nal steering method.