The Amplitude and phase of surface acoustic waves can be characterized using a laser beam and photodiode detector. This paper describes a technigue for charactarizing waves using the double photodiode method. This method is a modification of the knife-edge method, and involves focusing a laser beam to a beam spot smaller than the acoustic wavelength. The beam is reflected and the tilt of the reflection due to the surface acoustic wave is measured by a double photodiode. The laser beam chopped to the same frequency as the surface acoustic wave and amplitude modulation is applies in order for the photodiode to be able to detect the wave. The double photodiode measures the light shining on each half of the detector. The difference between signals from each half is then divided by the total signal and fed into a lock-amplifier that extracts the amplitude and phase information from the signal. The lock-in amplifier output signal can also be used to create 2D images of the surface acousitc wave using LabView or another similar program. The described method has been shown to be applicable to frequencies of 3GHz and will have a measured amplitude sensitivity of 1 andstrom.