An electrostatically controlled, tunable Fabry-Perot interferometer is provided with a first, fixed mirror (4) to which a floating electrode (2) is fitted, a second, movable mirror (6) to which first and second control electrodes (8, 10) are fitted, and a resonant cavity of length d, defined by the first and second mirrors. The application of an electrical voltage between the two control electrodes operates to cause displacement of the movable mirror in relation to the fixed mirror, thereby modifying the length of the resonant cavity of the Fabry-Perot interferometer.
A tunable optical cavity constructed from a fixed mirror and a movable mirror is disclosed. A circuit applies an electrical potential between first and second electrically conducting surfaces thereby adjusting the distance between the fixed and movable mirrors. The fixed mirror and the moveable mirror are positioned such that the mirrors form the opposite ends of the optical cavity. The distance between the fixed mirror and the moveable mirror is a function of the applied electrical potential. The thermally induced vibrations are reduced by utilizing an electrical feedback circuit that measures the distance between the mirrors. The feedback circuit dynamically changes the potential between the substrate and the support member so as to reduce fluctuations in the cavity resonance frequency.
A microelectromechanically tunable Fabry-Perot spectrophotometer is provided for color sensing. Optical fiber provides light input to a Fabry-Perot filter which is adjusted by a switched capacitor circuit. Spectral intensity is sensed by an integrated photodetector.
A tunable optical cavity constructed from a fixed mirror and a movable mirror. The fixed mirror is attached to a substrate having a first electrically conducting surface. A support member having the moveable mirror supported thereon and having a second electrically conducting surface, is suspended above the substrate. A circuit applies an electrical potential between the first and second electrically conducting surfaces thereby adjusting the distance between the fixed and movable mirrors. The fixed mirror and the moveable mirror are positioned such that the mirrors form the opposite ends of the optical cavity. The distance between the fixed mirror and the moveable mirror is a function of the applied electrical potential. The fixed mirror is mounted in a well in the substrate such that distance between the support member and the substrate is less than half the distance between the mirrors.
The invention relates to a method for controlling by electrical means the interelectrode distance of such a micromechanical electrode structure [(7,8)] in which at least one electrode [(7)] is attached elastically suspended on the surrounding structure, whereby the elastic properties of each electrode and the electrical control applied over the electrodes determine the interelectrode distance. According to the invention, the distance between the electrodes [(7,8)] is controlled by controlling the AC control current passing via the electrodes [(7,8)].
A Fabri-Perot filter includes: a substrate; a first mirror disposed on the substrate; and a movable mirror unit facing the first mirror with a gap therebetween. The movable mirror unit is movable toward the first mirror in a case where a predetermined voltage is applied between the first mirror and the movable mirror unit so that the gap is changeable. The filter is capable of transmitting an infrared light having a predetermined wavelength corresponding to the gap. The movable mirror unit includes a center portion and a periphery portion, which is deformable easier than the center portion.
