Abstract: In an optical microphone including a light source, a fiber optic cable and a Fabry-Perot interferometer with two reflectors, wherein one end face of the fiber optic cable forms a first reflector and the second reflector is arranged at a distance therefrom and is displaceable by fluctuations in the sound air pressure, the second reflector is the end face of a glass fiber section which is displaceable by induced air pressure by means of a separate diaphragm that is coupled thereto. The light source may be a super luminescent diode (SLD).

Abstract: An arrangement for measuring acceleration and vibration employs a fiber-optic interferometer comprising a monomode optical fiber through which light is guided and, having exited the fiber, is then reflected back therethrough, the exit end of the fiber being capable of transverse vibrations.

Abstract: A photoelectric beam device comprises a light source, a monomode optical fibre, a transmitting optical unit, a reflector and a photodetector, where the transmitting optical unit comprises a collimation optical unit, e.g. in the form of a graded index lens or rod lens and a beam expansion optical unit e.g. in the form of a telescopic optical unit. A fibre-optic directional coupler, arranged between the light source and the monomode fibre, conducts to the photodetector the optical signal reflected back from the reflector to the transmitting optical unit and refocused into the fibre.