In this paper we present a new technique for accomplishing the Fourier transformation of interferograms via total optical means. The technique involves: (1) Obtaining intsrferograms of input optical signals through scanning by a Michelson interferometer. (2) Accomplishing the time-to-space coordinate transformation of the interferograms by linearly recording on proper medium through a temporal-spatial transducer (KDP). (3) Completing the Fourier transformation of the spatial interferogram by using a coheroirt optical spoctrum analyzing system and then obtaining the spectrum of the input optical signal at the output plane of the system.