CN101808264A - Optical fiber laser microphone - Google Patents

Abstract

The invention discloses an optical fiber laser microphone which comprises a cylindrical shell, an optical fiber laser, a membrane, a cover, a cavity and a first hole. The cylindrical shell is used for protecting the internal structure and forming the cavity, both ends of the optical fiber laser are respectively fixed on the membrane and the cylindrical shell for detecting and converting an acoustical signal into an optical signal presenting the wavelength change of output laser, the membrane is used for sensing and transmitting the acoustical signal to the optical fiber laser, the cover is used for protecting the membrane and forming the cavity which is used for generating resonance or transmitting the acoustical signal to the membrane, and the first hole is arranged on the cover for transmitting the acoustical signal into the cavity and taking the filtration action. The invention greatly lowers the system noise, improves the capability of detecting weak signals, avoids the disturbance influence of a transmission optical fiber, and improves the system stability.

Description

Fiber Laser Microphone

technical field

The invention relates to the technical field of microphones, in particular to a fiber laser microphone.

Background technique

Microphones (microphones) are widely used in various fields of daily life, such as venues, telephones, computers, intercom systems, etc. Traditional electrical microphones have poor immunity to electromagnetic interference, and generally cannot work in harsh environments, such as wet environments or underwater environments.

Optical fiber microphone is an instrument that detects sound signals by using the light transmission characteristics of optical fiber and various modulation effects generated by its interaction with sound waves in the surrounding environment. Compared with traditional electrical microphones, fiber optic microphones have obvious advantages in terms of sensitivity, dynamic range, environmental adaptability, anti-electromagnetic interference, and reliability, and are particularly prominent in national defense and military applications.

Most of the currently reported fiber optic microphones use light intensity modulation technology. For example, utility model patent ZL200520060813.6 discloses a fiber optic microphone, which uses a reflective vibrating membrane to sense sound signals, and the end face of the optical fiber is placed parallel to the vibrating membrane. When the vibrating membrane vibrates due to sound, the intensity of light reflected into the optical fiber changes, so that the acoustic signal can be detected by detecting the intensity of light entering the optical fiber. The disadvantage of this method is that the sensitivity is low, and the stability of the system is affected by the transmission fiber.

Zhang Hongju and others also reported a fiber optic microphone probe (Applied Optics, Volume 29, No. 5, 2008), which also uses an elastic diaphragm as a sensitive element, and the reflected light intensity of the elastic diaphragm enters the optical fiber, thereby realizing sound detection. detection. Its disadvantages are the same as above.

Wang Jing and others reported a fiber Bragg grating microphone (Instrument Technology and Sensors, No. 10, 2009). In its technical solution, the Bragg grating is installed on the cantilever beam for sound detection, and the Bragg grating is vibrated by the vibration of the cantilever beam. The output wavelength of the grating changes, and the sound signal is detected by detecting the reflection wavelength of the Bragg grating. Its disadvantage is that the bandwidth of the Bragg grating is large, which makes the system noise higher, unable to detect extremely weak signals, and the sensitivity is also low.

Wu Dongfang and others proposed a fiber optic microphone based on MZ interferometer (Journal of Sensing Technology, Vol. 20, No. 7, 2007). Although it adopts a dry beam structure, it still needs to use the diaphragm to reflect the fiber optic light. There are also stability issues.

In view of the problems in the above technical solution that the system is unstable due to the influence of the transmission fiber, the sensitivity is low, and it is impossible to detect weak signals, the present invention proposes a fiber laser microphone for sound detection, focusing on solving system stability and detecting weak signals Ability issue.

Contents of the invention

(1) Technical problems to be solved

In view of this, the main purpose of the present invention is to provide a fiber laser microphone to solve the problems of system stability and ability to detect weak signals.

(2) Technical solution

In order to achieve the above object, technical solution of the present invention is achieved in that way:

A fiber laser microphone, the fiber laser microphone includes:

Cylindrical shell 10 for protecting the internal structure and forming a first chamber 15;

A fiber laser 20, the two ends of which are respectively fixed on the diaphragm 30 and the cylindrical shell 10, are used to detect the sound signal and convert the sound signal into an optical signal that the fiber laser 20 is used to indicate the change of the output laser wavelength;

The diaphragm 30 is used to sense the sound signal and transmit the sound signal to the fiber laser 20;

The cover 40 is used to protect the diaphragm 30 and form a second chamber 45;

The second cavity 45 is used to generate resonance or transmit the sound signal to the diaphragm 30;

The first hole 41 is opened on the cover 40, and is used to transmit the sound signal to the second cavity 45 and play a filtering role.

In the above solution, the fiber laser 20 is a distributed Bragg reflection fiber laser or a distributed Bragg feedback fiber laser, which is used to sense the sound signal.

In the above solution, the cylindrical shell 10 is further provided with a second hole 11 for leading out the tail optical fiber of the fiber laser 20 .

In the above solution, a screw is further installed in the center of the diaphragm 30 for fixing one end of the fiber laser 20 .

In the above solution, the fiber laser 20 has a certain initial tensile stress, so that the fiber laser 20 maintains a straightened state.

In the above solution, the diameter of the first hole 41 can be changed according to needs, so as to adjust the acoustic performance of the fiber laser microphone.

(3) Beneficial effects

As can be seen from the foregoing technical solutions, the present invention has the following beneficial effects:

1. The fiber laser microphone provided by the present invention uses a fiber laser to sense sound signals, and the line width of the fiber laser is very narrow, thereby greatly reducing system noise and improving the ability to detect weak signals.

2. The fiber laser microphone provided by the present invention uses a fiber laser to sense sound signals and adopts a wavelength modulation scheme instead of a reflection intensity modulation scheme, thereby avoiding the influence of transmission fiber disturbance and improving system stability.

Description of drawings

FIG. 1 is a schematic structural view of a fiber laser microphone provided according to a first embodiment of the present invention;

Fig. 2 is a schematic structural diagram of a fiber laser microphone provided according to a second embodiment of the present invention.

Detailed ways

In order to make the object, technical solution and advantages of the present invention clearer, the present invention will be described in further detail below in conjunction with specific embodiments and with reference to the accompanying drawings.

Please refer to FIG. 1 , which is a schematic structural diagram of a fiber laser microphone according to a first embodiment of the present invention. The Fiber Laser Microphone includes:

Cylindrical shell 10 for protecting the internal structure and forming a first chamber 15;

The two ends of the fiber laser 20 are respectively fixed on the diaphragm 30 and the cylindrical shell 10, and are used to detect the sound signal, and convert the sound signal into an optical signal that the fiber laser 20 is used to indicate the change of the output laser wavelength. The fixing method is generally bonding;

The diaphragm 30 is used to sense the sound signal and transmit the sound signal to the fiber laser 20;

The cover 40 is used to protect the diaphragm 30 and form a second chamber 45;

The second cavity 45 is used to generate resonance or transmit the sound signal to the diaphragm 30;

The first hole 41 opened on the cover 40 is used to transmit the sound signal into the second cavity 45 and play a filtering role.

The fiber laser 20 is a Distributed Bragg Reflection (DBR) fiber laser or a Distributed Bragg Feedback (DFB) fiber laser, and is used for sensing sound signals. A second hole 11 is further opened on the cylindrical shell 10 for leading out the tail fiber of the fiber laser 20 . A screw can be further installed in the center of the diaphragm 30 for fixing one end of the fiber laser 20 , and the fixing method is generally bonding. The fiber laser 20 generally has a certain initial tensile stress, so that the fiber laser 20 maintains a straightened state. The diameter of the first hole 41 opened on the cover 40 can be changed according to needs, so as to adjust the acoustic performance of the fiber laser microphone.

As shown in this embodiment, the diameter of the first hole 41 is very small relative to the cover 40, then the second cavity 45 constitutes a Helmholtz resonator, and the performance of the resonator can be changed by modulating the diameter of the first hole 41, So as to achieve the effect of filtering the sound.

The working principle of the fiber laser microphone provided by the present invention is that when the fiber laser microphone is pumped with pumping laser light, the fiber laser 20 in the fiber laser microphone emits laser light after pumping. When there is sound, the sound can enter the second cavity 45 through the first hole 41 , thereby causing the second cavity 45 to resonate and cause the diaphragm 30 to vibrate. The diaphragm 30 transmits the sound pressure vibration signal to the fiber laser 20 , thereby causing the wavelength of the output laser light of the fiber laser 20 to change. The change can be demodulated by a subsequent demodulation system using an appropriate demodulation method (such as the method of phase generation carrier wave) to demodulate the sound signal.

Please refer to FIG. 2 , which is a schematic structural diagram of a fiber laser microphone according to a second embodiment of the present invention. The Fiber Laser Microphone includes:

Cylindrical shell 10 for protecting the internal structure and forming a first chamber 15;

A fiber laser 20, the two ends of which are respectively fixed on the diaphragm 30 and the cylindrical shell 10, are used to detect the sound signal and convert the sound signal into an optical signal that the fiber laser 20 is used to indicate the change of the output laser wavelength;

The diaphragm 30 senses the sound signal and transmits the sound signal to the fiber laser 20;

The cover 40 is used to protect the diaphragm 30 and form a second chamber 45;

The second cavity 45 is used to generate resonance or transmit the sound signal to the diaphragm 30;

The first hole 41 opened on the cover 40 is used to transmit the sound signal into the second cavity 45 and play a filtering role.

The fiber laser 20 is a Distributed Bragg Reflection (DBR) fiber laser or a Distributed Bragg Feedback (DFB) fiber laser, and is used for sensing sound signals. A second hole 11 is further opened on the cylindrical shell 10 for leading out the tail fiber of the fiber laser 20 . A screw may be further installed in the center of the diaphragm 30 for fixing one end of the fiber laser 20 . The fiber laser 20 generally has a certain initial tensile stress, so that the fiber laser 20 maintains a straightened state. The diameter of the first hole 41 opened on the cover 40 can be changed according to needs, so as to adjust the acoustic performance of the fiber laser microphone.

As shown in this embodiment, the diameter of the first hole 41 is equivalent to the inner diameter of the cover 40, then the sound can directly pass through the second cavity 45 and act on the diaphragm 30. At this time, the second cavity 45 and the first hole 41 are not connected. produces a filtering effect.

The working principle of the fiber laser microphone provided by the present invention is that when the fiber laser microphone is pumped with pumping laser light, the fiber laser 20 in the fiber laser microphone emits laser light after pumping. When there is sound, the sound may pass through the second cavity 45 to act on the diaphragm 30 and cause the diaphragm 30 to vibrate. The diaphragm 30 transmits the sound pressure vibration signal to the fiber laser 20 , thereby causing the wavelength of the output laser light of the fiber laser 20 to change. The change can be demodulated by a subsequent demodulation system using an appropriate demodulation method (such as the method of phase generation carrier wave) to demodulate the sound signal.

In this embodiment, in order to protect structures such as the diaphragm 30 in the second chamber 45 , a windshield 50 can be further installed on the cover 40 to protect the internal structure while reducing noise.

The specific embodiments described above have further described the purpose, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above descriptions are only specific embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included within the protection scope of the present invention.

Claims (6)

1. A fiber laser microphone, characterized in that, the fiber laser microphone comprises: A cylindrical shell (10) for protecting the internal structure and forming a first chamber (15); The fiber laser (20), the two ends of which are respectively fixed on the diaphragm (30) and the cylindrical shell (10), are used to detect the sound signal and convert the sound signal into the light used by the fiber laser (20) to represent the change of the output laser wavelength Signal; The diaphragm (30) is used to sense the sound signal and transmit the sound signal to the fiber laser (20); A cover (40) for protecting the diaphragm (30) and forming a second cavity (45); The second chamber (45) is used to generate resonance or transmit sound signals to the diaphragm (30); The first hole (41), opened on the cover (40), is used to transmit the sound signal to the second cavity (45) and play a filtering role. 2 . The fiber laser microphone according to claim 1 , wherein the fiber laser ( 20 ) is a distributed Bragg reflection fiber laser or a distributed Bragg feedback fiber laser for sensing sound signals. 3 . 3. The fiber laser microphone according to claim 1, characterized in that, the cylindrical housing (10) is further provided with a second hole (11) for leading out the tail optical fiber of the fiber laser (20). 4. The fiber laser microphone according to claim 1, characterized in that a screw is further installed in the center of the diaphragm (30) for fixing one end of the fiber laser (20). 5. The fiber laser microphone according to claim 1, characterized in that, the fiber laser (20) has a certain initial tensile stress to keep the fiber laser (20) in a straightened state. 6. The fiber laser microphone according to claim 1, characterized in that, the diameter of the first hole (41) can be changed in size as required, so as to adjust the acoustic performance of the fiber laser microphone.

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