Method for determining full-field absolute phases in the common-path heterodyne interferometer with an electro-optic modulator.

When a sawtooth voltage signal with the amplitude lower than its half-wave voltage is applied to drive an electro-optic modulator, the interference signals become a group of periodic sinusoidal segments. A new algorithm is proposed to modify these segments to an associated continuous sinusoidal wave, and then its initial phase can be determined. Subtracting the characteristic phase of the modulator from the initial phase, the absolute phase can be obtained. This technique is applied to all pixels, and full-field absolute phase measurements can be achieved. The validity of this method is demonstrated.