A lamellar grating interferometer (LGI) realized by silicon micro-machining is presented. The LGI is a binary grating with a variable depth. The motion is carried out by an electrostatic comb drive actuator fabricated by silicon-on-insulator (SOI) technology. It is used as Fourier transform spectrometer (FTS). We have measured an optical path difference maximum of 82 μm. The measured resolution of the spectrometer after the phase correction is 6 nm at a wavelength of 633 nm. A preliminary measurement with a xenon arc lamp is shown.