Abstract: An optical microphone element comprising a diaphragm (31) vibrating with sound pressure, a case (40) containing the diaphragm (31) and having first and second openings (38, 39) made in symmetric positions and facing the diaphragm (31), a light source (32) for irradiating the diaphragm (31) with a light beam, and a photodetector (35) for receiving the light beam reflected by the diaphragm (31) and outputting a signal corresponding to vibration of the diaphragm (31).

Abstract: A device for collecting sounds from objects comprises a plurality of microphones whose directivity can be varied depending on the environment in which each object is located. An optical microphone includes a vibration board (2) which vibrates by sound pressure, a light source (3) for emitting a light beam to the vibration board (2), a photodetector (5) which receives the light beam reflected from the vibration board (2) and produces a signal corresponding to the vibration of the vibration board (2), a drive circuit (13) for supplying the light source (3) with predetermined current, and a negative feedback circuit (100) that supplies the drive circuit (13) with a negative feedback signal consisting of a signal output from the photodetector (5). The negative feedback circuit (100) changes the amount of negative feedback depending on the environment.

Abstract: A device for collecting sounds comprises a plurality of microphones arranged in a predetermined pattern, wherein selected microphones are directed to an object. A microphone selection and control unit (60) selects at least one of a plurality of microphones and drives the selected microphone to collect sound from the object and output a signal. An optical microphone includes a vibration board (2) which vibrates by sound pressure, a light source (3) for emitting a light beam to the vibration board (2), a photodetector (5) which receives the light beam reflected from the vibration board (2) and produces a signal corresponding to the vibration of the vibration board (2), and a drive circuit (13) for supplying the light source (3) with predetermined current.

Abstract: Provided is a microphone with a stable output employing an aluminum membrane and having an air escape provided to the vibration detector. Specifically, the material used as the membrane frame material has a larger Young's modulus and a smaller thermal expansion coefficient than those of aluminum. Thereby, even if stress distribution or heat distribution is inflicted on the membrane frame, the slack or tension in the membrane will be reduced and the microphone output is stabilized.

Abstract: An optical microphone element comprising a diaphragm (31) vibrating with sound pressure, a case (40) containing the diaphragm (31) and having first and second openings (38, 39) made in symmetric positions and facing the diaphragm (31), a light source (32) for irradiating the diaphragm (31) with a light beam, and a photodetector (35) for receiving the light beam reflected by the diaphragm (31) and outputting a signal corresponding to vibration of the diaphragm (31).

Abstract: An optical microphone in which the difference between the sum of the thickness of a light emission element mounting substrate 3 and the height of a light emission element 1 and the sum of the thickness of a light-receiving element mounting substrate 4 and the height of a light-receiving element 2 is made smaller than the difference between the height of the light emission element 1 and the height of the light-receiving element 2. The optical path is thereby reduced, and the intensity of the light reaching the light-receiving element is increased, changes in the output of the light-receiving element caused by the vibration of the membrane film are increased, and the sensitivity of the microphone is increased. It is preferable that the sum of the thickness of the light emission element mounting substrate 3 and the height of the light emission element 1 and the sum of the thickness of a light-receiving element mounting substrate 4 and the height of the light-receiving element 2 are equal.

Abstract: The invention provides a small optical microphone/sensor (2) for measuring distances to, and/or physical properties of, a reflective surface, comprising a source of light (4) coupled to a light waveguide (6) for transmitting a light beam through the waveguide; the waveguide (6) having at one of its ends a pointed face (12) with an angle determined by Snell's Law of Refraction 1 sin ⁢   ⁢ α 1 sin ⁢   ⁢ α 2 = n 2 n 1

Abstract: There is disclosed an optical microphone which reduces hindrance to the vibration of a membrane with respect to the input elastic wave, to thereby obtain a linear output current fluctuation with respect to the input elastic wave. Specifically, the total area of an outlet window 8 for performing irradiation and an inlet window 7 for receiving light is made equal to or less than 5% of the area of a membrane 5. And the vertical sectional shape of a light-guiding portion 9 includes a multidimensional function curve portion of 1.2 dimension or more. Moreover, the sectional shape is such that if an angle formed between the substrate and the tangent of the sectional shape at an intersection of the curve and a normal with respect to the substrate respectively extended from the light emission element and the light-receiving element is designated as &agr;, the critical angle of the light-guiding portion material becomes larger than 180-2&agr;.

Abstract: The invention provides an echo-cancelling system for an optical microphone, for eliminating acoustical echoes from a source of acoustical signals to which the microphone is connected, the system including a source of light for illuminating the acoustical membrane; a photodetector for receiving light reflected from the membrane and for producing output signals; means for supplying power to the source of light; a preamplifier for amplifying the output signals; an input terminal for receiving electrical signals from the source of acoustical signals; a time delay circuit for receiving signals from the source of acoustical signals, and a circuit for regulating the amplitude of the delayed electrical signals, connected between the delay circuit and the source of light, for changing the current supplied to the source of light by the light source power means.

Abstract: The invention provides a smart optical microphone/sensor for sensing distances to a membrane or to a light-reflecting surface, including a source of light for illuminating the membrane or light-reflecting surface; a photodetector for receiving light reflected from the membrane or light-reflecting surface and for producing output signals; adjustable means for supplying power to the source of light, and a pre-amplifier for amplifying the output signals, whereby the sensitivity of the microphone/sensor can be adjusted.

Abstract: The invention provides a sensor for measuring the distances to a medium and/or the physical properties thereof, including a housing; at least one pair of optical fibers, each having an input end portion and an output end portion, the input end portion of a first fiber being connectable to a source of light and the output end portion of a second fiber being connectable to light intensity measuring means; a sensor head, including the input end portion of the second optical fiber and the output end portion of the first optical fiber affixedly located at least in proximity to each other; each of the output end portion of the first fiber and input end portion of the second fiber having an axis and a rim, the rims being cut at an angle &thgr; with respect to the axis and the axes forming an angle &agr; therebetween, and wherein, upon operation, the light emerging from the output end portion of the first fiber impinges on a surface of a medium at an angle of incidence &bgr;, and wherein &bgr;=ƒ(&agr;,&th

Abstract: The invention provides a sensor for sensing the distances to a medium and/or displacements and the physical properties thereof, including a housing, at least one pair of solid light guides each having an input end face and an output end face, at least one source of light and at least one light intensity measuring means, the input end face of a first light guide being optically coupled to a source of light an d the output end face of a second light guide being optically coupled to a light intensity measuring means, the light guides being optically isolated from each other while at least the faces thereof are located adjacent to each other, each of the faces being cut at an angle .theta. with respect to the optical axis of its waveguide, so as to include an angle a between the axes thereof, the arrangement being such that, upon operation, the light emerging from the output end portion of the first light guide impinges on a surface of a medium at an angle of incidence .beta., and wherein .beta.=.function.(.

Abstract: A noise attenuation system for use with sound receiving devices, including first and second relatively small optical microphone devices having at least one sound responsive membrane operative to produce an output signal in accordance with sound waves picked up by the optical microphone devices, at least one pair of light guides affixed to the first or second optical microphone devices, the pair of light guides each having an input end portion and an output end portion, the input end portion of a first light guide is connectable to a source of light and the output end portion of the second light guide is connectable to a light intensity detecting means. Each of the output portion of the first light guide and input end portion of the second light guide has an axis and a rim and is oriented with respect to each other to include an angle between the axes, and each of the light guide rims is cut at an angle with respect to the axis of its light guide.

Abstract: A sensor for sensing the distances to a medium and/or the physical properties thereof, including a housing, at least one pair of optical fibers, each having an input end portion and an output end portion, the input end portion of a first fiber being connectable to a source of light and the output end portion of a second fiber being connectable to a light intensity measuring device. The sensor further includes the input and output end portions, wherein each of the output portion of the first fiber and input end portion of the second fiber has an axis and a rim, the rim being cut at an angle .THETA. with respect to the axis and being affixedly located in a plane at least in proximity to, and facing, each other, so as to include an angle .alpha. between the axes thereof. The arrangement is such that, upon operation, the light emerging from the output end portion of the first fiber impinges on a surface of a medium, at an angle of incidence .beta., and wherein .beta.=.function.(.alpha.,.THETA.).