An electrostatically tunable Fabry-Perot interferometer produced by surface micromechanical techniques is used in optical material analysis as an optical sweeping filter in which the optical measurement wavelength is centered at a wavelength .lambda.. The Fabry-Perot interferometer based sensor structure comprises a body block, two essentially parallel mirrors bonded to the body block, of which mirrors at least one is partially transmitting and movable relative to the body block. The mirrors are spaced maximally by a few half-wavelengths, .lambda./2, from each other, and both of the mirror structures include integral electrode structures capable of effecting an electrostatic force between the mirror structures. The movable mirror structure is provided with structurally weakened regions surrounding the optical area of the mirror so as to facilitate keeping the optical area at a maximum degree of flatness. At least one of the electrode structures surrounds the optical area so as to achieve a mechanical lever action and avoid galvanic contact between the electrode of the movable mirror structure and the electrode of the fixed mirror structure.
