Focal Law Calculations for Annular Phased Array Transducers

One of the most important characteristics of annular arrays is their superior focal capabilities. In order to achieve the desired focussing, each of the elements is fired in different times. The delay times used for beam focussing are called focal laws. The focal laws are automatically calculated from the inspection software. In order to make sure that the focal laws are calculated correctly from the software, it is wise to validate the focal laws for a particular configuration. The validation/comparison will involve the calculation of focal law values using three different methods, from the experimental acquisition software (TWI software) and from simulation software (CIVA). Moreover, one of the methods introduces the concept of centre of mass as an exit point of the beam, which is novel to be investigated because previously only the geometric centre was considered for annular arrays.