High frequency broadband arbitrary coded excitation in ultrasound microscopy

We built a 200+ MHz ultrasound microscope that can employ broad band arbitrary coded signals. Our solution is based on quadrature modulation and T/R-switching. We show that the instrument works with linear and non-linear chirp signals (100 - 300 MHz). We imaged a 5 μm tall MEMS step structure with our device and with a commercial pulser, the results were comparable. Cross-talk from the local oscillator in the quadrature modulator affects the pulse compression. This limits the use of codes at the oscillator frequency.