A method of measuring conditions of an ultrasonic instrument includes providing an ultrasonic instrument that includes an end effector and a waveguide operably coupled to a generator and the end effector. The method involves generating one or more pulses with the generator, transmitting the one or more pulses to one or both of the waveguide and the end effector, generating one or more waves that scatter in an interferential pattern in response to the transmission of the one or more pulses, registering a signal indicative of the interferential pattern, generating an actual interferential pattern based upon the signal, and identifying one or more conditions of the end effector based upon the actual interferential pattern.