The conventional method used to map the field of high intensity focused ultrasound (HIFU) transducers displaces a hydrophone over a grid of points in the zone of interest and provides a direct measure of the ultrasound pressure at each point. The approach has several major limitations: (1) the hydrophone is likely to be damaged while repeatedly measuring high intensity fields, (2) the resolution of the field map is limited to the size of the active area of the hydrophone which is typically on the order of 0.5 mm and large compared to some wavelengths of interest, and (3) cavitation can limit the accuracy of measurements. By placing a small scatterer in the HIFU field and measuring the scattered wave with a sensitive hydrophone from a safe distance, the field can be measured at full power without harm. We have used this technique to acquire single frequency field maps of HIFU transducers at high intensities without any damage to the hydrophone. We also have been able to improve the spatial resolution of the field map by an order of magnitude. In addition, this technique permits measurement of some non-linear behavior (e.g., harmonic content) at the focus at high intensities.