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Beamformer
The beam is focused and steered in an ultrasound transducer by exciting each crystal element at a different time so that sound waves arrive simultaneously at the focal point. Elements further from the focal point must be excited earlier to account for the longer distance. This phasing of element excitation based on the focal point location is known as beam formation and allows the returning echo to be properly interpreted.
Beamformer
- 1. Beam formerIn atransducer with multi-element solid state crystals, the beam is focused and steered by exciting each of the elements at a different time so that the resulting sound wave coming from each crystal will arrive at the intended focal point simultaneously. In case A, the beam is being focused and steered to the left. Note that the distance from the focal point to element 1 of the transducer is shorter than the distance from the focal point to element 4. This means that in order for the waves generated by each element to arrive at the focal point simultaneously, element 4 must be excited before elements 1, 2, and 3. Likewise, in case B, the focal point is to the right, so the elements of the transducer must be excited in the reverse order. This process of phasing the firing of elements is "beam formation."
- 2. Beam FormerIn thiscase, it is easy to see that the echo returning from point A encounters element 1 before it encounters element 4. Thus, the signals coming into the ultrasound scanner from the various elements must be delayed so that they all "arrive" at the same moment. The signals from each element are summed together to form the ultrasound signal that is subsequently processed by the rest of the ultrasound instrument.