The optical interferometry for the surface profile measurement,with an ability of high-accuracy and non-contact measurement,has a wide application in industrial production and scientific research.In this paper,a sinusoidal phase modulating(SPM) interferometer to realize real-time surface profile measurement is proposed,and its measurement principle is analyzed theoretically.In the SPM interferometer,the interference signal is detected by a high speed image sensor based on a low-speed CCD and discriminated b...