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Optical microphone

A microphone and optical technology, used in optical signal detection transducers, microphones, sensors, etc., can solve the problem of reducing the detection sensitivity of acoustic signals, and achieve the effect of improving detection sensitivity and high tolerance

Inactive Publication Date: 2013-07-24
PANASONIC CORP
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

In addition, when the diaphragm is miniaturized in order to obtain wide-band performance, the detection sensitivity of the acoustic signal will decrease

Method used

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no. 1 Embodiment approach

[0070] figure 1 The configuration of the first embodiment of the optical microphone of the present invention is shown. The optical microphone 1 includes a detection optical system 2 and a signal processing system 17 . The detection optical system 2 detects an acoustic signal propagating in the environment around the optical microphone 1 to generate an electrical signal, and the signal processing system 17 performs signal processing on the electrical signal to generate a reception signal 12 . Each component will be described below.

[0071]

[0072] The detection optical system 2 includes a light source 4 , a first polarizing plate 5 , an elliptical polarization generating unit 6 , a sound receiving unit 7 , a second polarizing plate 8 , and a photodetector 9 .

[0073] Light source 4 emits light 3 . In this embodiment, the light 3 used can be coherent light or incoherent light. In addition, the occupied wavelength band of the light 3 may be a single band, a narrow band,...

no. 2 Embodiment approach

[0155] Figure 16 The configuration of the first embodiment of the optical microphone of the present invention is shown. The optical microphone 1' includes a detection optical system 2' and a signal processing system 17. Similar to the first embodiment, the detection optical system 2' detects an acoustic signal propagating in the environment around the optical microphone 1' to generate an electrical signal, and the signal processing system performs signal processing on the electrical signal to generate a received signal 12. . exist Figure 16 In , the same reference numerals are assigned to the same components as those in the first embodiment. In this embodiment, a quarter-wave plate 92 is used as the elliptically polarized generation unit 6 .

[0156] In the optical microphone 1', the relative angles of the optical axes of the first polarizing plate 5, the second polarizing plate 8, and the 1 / 4 wavelength plate 92 serving as the elliptical polarization generator 6 are dif...

no. 3 Embodiment approach

[0166] Figure 19 (a) to (d) show the third embodiment of the optical microphone of the present invention. In these embodiments, although the signal processing unit is not shown, the signal processing unit described in the first and second embodiments is included. In the first and second embodiments, the detection optical systems 2, 2' have components arranged in a row along the light beam 3. However, the components in the detection optical systems 2, 2' may not be arranged in a row. In this embodiment, reflected light is used to form the optical path of the detection optical system.

[0167] Figure 19 The optical microphone shown in (a) includes a light source 4 , a first polarizer 5 , an elliptical polarization generator 6 , a second polarizer 8 , a photodetector 9 , a sound receiver 7 , a beam splitter 201 , and a mirror 202 .

[0168]The light 3 emitted from the light source passes through the first polarizer 5 and the elliptically polarized generation unit 6 and ente...

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Abstract

An optical microphone is provided with: a light source (4); a first polarizer (5) for passing the straight polarization light from among the light beams emitted from the light source (4); a second polarizer (8) having a polarization plane that is different from the first polarizer (5) and for passing the straight polarization light; a sound receiving unit (7) having an opening and an acoustic medium through which acoustic signals that entered from the opening are propagated and which has a slower sound velocity than air, the sound receiving unit (7) being disposed in a manner such that the straight polarization light that passed through the first polarizer passes through the acoustic medium by cutting across a path for propagating the acoustic signals and enters the second polarizer; and a light detector (9) for converting the intensity of light that passed through the second polarizer (8) into electric signals. A different phase shift is applied to the straight polarization light that passed through the first polarizer between the first polarizer and the second polarizer in two directions that intersect one another and that are different from the polarization direction.

Description

technical field [0001] This application relates to optical microphones that use light to detect acoustic signals. Background technique [0002] Conventionally, microphones that use a diaphragm to detect acoustic signals and convert them into electrical signals have been widely used. This type of microphone has a diaphragm as part of mechanical vibration. Therefore, the characteristics of the diaphragm may change during repeated use of the microphone. In addition, when a high-intensity acoustic signal is detected using a microphone, the vibrating membrane of the microphone may be greatly vibrated due to the acoustic signal, and the vibrating membrane may be damaged. [0003] Furthermore, the microphone cannot expect to detect good acoustic signals at frequencies equal to or higher than the lowest resonance frequency of the vibrating membrane. Therefore, it is difficult for the microphone to detect frequencies in a wide band (hereinafter referred to as "broadband property")...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H04R23/00
CPCH04R23/008H04R2410/00H04B10/114
Inventor 寒川潮岩本卓也金子由利子桥本雅彦
Owner PANASONIC CORP
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