High-Intensity Focused Ultrasound (HIFU) has been applied as an acceptable therapeutic technique and various HIFU systems have achieved clinical approval for general use in numerous countries. To ensure that an HIFU system is used in a safe and reliable application, its acoustic field needs to be characterized accurately. However, the traditional methods mostly are based on hydrophones, these sensors are found short of sufficient temporal and spatial resolutions, especially, they can only tolerate small acoustic pressures. This work is concerned with the feasibility of optical interferometry in measuring focused acoustic fields and in predicting HIFU fields.