Transducer system

Abstract

A device ( 100 ) for converting an acoustic signal ( 102 ) into an electric signal ( 104 ), wherein the device ( 100 ) comprises an interferometer ( 106 ) comprising two mirrors ( 108 ) adapted for reflecting electromagnetic radiation ( 112 ) coupled into a space ( 110 ) between the mirrors ( 108 ), wherein the acoustic signal ( 102 ) is to be coupled into the space ( 110 ) for influencing the electromagnetic radiation ( 112 ) in accordance with the acoustic signal ( 102 ), an electromagnetic radiation detector ( 112 ) adapted for detecting the influenced electromagnetic radiation ( 112 ) and for converting the detected influenced electromagnetic radiation ( 112 ) into the electric signal ( 104 ) being indicative for the acoustic signal ( 102 ), and an operation point stabilization unit adapted for stabilizing an operation point of the device ( 100 ).

1 . A device for converting an acoustic signal into an electric signal, wherein the device comprises:
 an interferometer comprising two mirrors adapted for at least partially reflecting electromagnetic radiation coupled into a space between the mirrors, wherein the acoustic signal is to be coupled into the space for influencing the electromagnetic radiation in accordance with the acoustic signal;   an electromagnetic radiation detector adapted for detecting the influenced electromagnetic radiation and for converting the detected influenced electromagnetic radiation into the electric signal being indicative of the acoustic signal; and   an operation point stabilization unit adapted for stabilizing an operation point of the device.   
     
     
         2 . The device according to  claim 1 , wherein the operation point stabilization unit is adapted for stabilizing the operation point by monitoring at least one parameter, optionally, the electric signal, indicative of the present operation point of the device and, upon determining a deviation of the present operation point from a predefined target operation point, controlling the device so that the operation point is returned to the target operation point. 
     
     
         3 . The device according to  claim 1 , wherein the interferometer is one of a Fabry-Pérot interferometer, an etalon, and a Gires-Tournois arrangement. 
     
     
         4 . The device according to  claim 1 , wherein the two mirrors are adapted for reflecting optical light coupled into the space between the mirrors. 
     
     
         5 . The device according to  claim 1 , wherein the electromagnetic radiation detector comprises a photodiode. 
     
     
         6 . The device according to  claim 1 , wherein the electromagnetic radiation detector is mechanically attached directly on one of the two mirrors. 
     
     
         7 . The device according to  claim 1 , further comprising an electromagnetic radiation source adapted for generating the electromagnetic radiation to be coupled into the space between the mirrors. 
     
     
         8 . The device according to  claim 7 , wherein the electromagnetic radiation source is adapted for generating the electromagnetic radiation modulated on a carrier wave in the high frequency domain. 
     
     
         9 . The device according to  claim 7 , wherein the electromagnetic radiation source is mechanically attached directly on one of the two mirrors. 
     
     
         10 . The device according to  claim 7 , wherein the electromagnetic radiation source comprises a laser. 
     
     
         11 . The device according to  claim 7 , wherein the electromagnetic radiation source is adapted for generating a divergent electromagnetic radiation between the two mirrors. 
     
     
         12 . The device according to  claim 7 , wherein the electromagnetic radiation source comprises a further electromagnetic radiation detector one of integrated in and attached to the electromagnetic radiation source. 
     
     
         13 . The device according to  claim 1 , wherein the operation point stabilization unit comprises an amplifier having an input coupled to the electromagnetic radiation detector and having an output at which the electric signal being indicative for the acoustic signal is provided. 
     
     
         14 . The device according to  claim 12 , further comprising a differential amplifier having a first input coupled to the electromagnetic radiation detector, having a second input coupled to the further electromagnetic radiation detector and having an output at which the electric signal being indicative for the acoustic signal is provided. 
     
     
         15 . The device according to  claim 1 , further comprising a rigid connection element rigidly connecting the two mirrors to one another and delimiting the space between the mirrors. 
     
     
         16 . The device according to  claim 1 , wherein the operation point stabilization unit comprises an electric signal separator adapted for separating the electric signal provided by the electromagnetic radiation detector into a direct current component and into an alternating current component, wherein the alternating current component is considered as being indicative for the acoustic signal. 
     
     
         17 . The device according to  claim 7 , wherein the operation point stabilization unit is adapted for adjusting an electric drive current powering the electromagnetic radiation source to adjust the wavelength of the electromagnetic radiation to thereby adjust the operating point. 
     
     
         18 . The device according to  claim 7 , wherein the operation point stabilization unit comprises a feedback circuit being supplied with the direct current component, wherein the feedback circuit is adapted for determining an actual operating point of the device based on the direct current component and is adapted for controlling the electromagnetic radiation source to drive the device towards a predefined reference operating point. 
     
     
         19 . The device according to  claim 1 , wherein the device is monolithically integrated in a substrate. 
     
     
         20 . The device according to  claim 1 , wherein the two mirrors are parallel aligned fixed mirrors. 
     
     
         21 . The device according to  claim 1 , wherein each of the two mirrors has a reflective surface facing a reflective surface of the other one of the two mirrors and has a non-reflective surface opposing the corresponding reflective surface and being covered with an anti reflection coating. 
     
     
         22 . The device according to  claim 1 , included in at least one of a microphone, an audio surround system, a mobile phone, a headset, a headphone playback apparatus, a loudspeaker playback apparatus, a hearing aid, a television device, a video recorder, a monitor, a gaming device, a laptop, an audio player, a DVD player, a CD player, a harddisk-based media player, a radio device, an internet radio device, a public entertainment device, an MP3 player, a hi-fi system, a vehicle entertainment device, a car entertainment device, a medical communication system, a medical device, a blood probe, a body-worn device, a speech communication device, a home cinema system, a home theatre system, a flat television apparatus, an ambiance creation device, a subwoofer, an acoustic measurement system, a sound level meter, a studio recording system, a pressure sensor, an ultrasound sensor, and a music hall system. 
     
     
         23 . The device according to  claim 1 , included in at least one of a software-based device, a device using at least one electronic hardware circuit, a hybrid device comprising software components and hardware components, an integrated hardware chip, and an ASIC. 
     
     
         24 . A method of converting an acoustic signal into an electric signal, wherein the method comprises
 at least partially reflecting electromagnetic radiation coupled into a space between two mirrors of an interferometer;   coupling the acoustic signal into the space for influencing the electromagnetic radiation in accordance with the acoustic signal;   detecting the influenced electromagnetic radiation and converting the detected influenced electromagnetic radiation into the electric signal being indicative for the acoustic signal; and   stabilizing the method at a present operation point.   
     
     
         25 . A computer-readable medium, in which a computer program for converting an acoustic signal into an electric signal is stored, which computer program, when executed by a processor, effects the method according to  claim 24 . 
     
     
         26 . A program element of converting an acoustic signal into an electric signal, which program element, when executed by a processor, is adapted to effect a method according to  claim 24 .