Optical microphone

Abstract

The utility model discloses an optical microphone which comprises a first optical device and a second optical device which are oppositely arranged, a resonant cavity is formed between the first optical device and the second optical device, optical signals transmitted in the resonant cavity can be influenced by external sound wave signals, and a light input part which inputs light to the first optical device, the first optical device and the second optical device are arranged in parallel and further input light to a resonant cavity formed by the first optical device and the second optical device, the light receiving part receives light signals which come from the resonant cavity and are influenced by sound wave signals, and at least one of the first optical device and the second optical device is a curved-surface reflecting mirror.

Description

Technical Field

[0001] This patent relates to the field of fiber optic sensors, and in particular to an optical microphone. Background Technology

[0002] Compared to traditional piezoelectric microphones, fiber optic microphones offer advantages such as long-distance transmission, simple structure, and strong environmental adaptability. Fiber optic microphones can be divided into diaphragm-based and diaphragmless types. Diaphragm-based optical microphones detect sound waves by analyzing the displacement of a diaphragm due to its vibration, but due to the limitation of the diaphragm's resonant frequency, the frequency range is limited to only tens of kHz. Diaphragmless optical microphones sense sound waves by measuring changes in the refractive index of air, achieving a frequency range reaching the MHz level.

[0003] Currently, diaphragmless optical microphones are mostly based on two parallel planes or FP etalons. However, due to factors such as surface shape errors, tilt angles, and material attenuation of the parallel planes, the loss of optical power is very large. Especially when the reflectivity of the parallel planes is high, the insertion loss caused by these errors increases exponentially. In addition to the manufacturing errors of the parallel planes themselves, the assembly process of the two parallel planes also requires extremely high precision. Current processes result in large errors and high costs. Utility Model Content

[0004] In view of the shortcomings of the prior art, the purpose of this application is to propose an optical microphone with simple manufacturing process, low insertion loss and high resonant cavity precision.

[0005] This utility model provides an optical microphone, comprising: a first optical device and a second optical device disposed opposite to each other, the first optical device and the second optical device forming a resonant cavity, the optical signal transmitted in the resonant cavity being affected by an external acoustic signal, a light input unit that inputs light to the first optical device and further inputs light to the resonant cavity formed by the first optical device and the second optical device, and a light receiving unit that receives the optical signal affected by the acoustic signal from the resonant cavity, wherein at least one of the first optical device and the second optical device is a curved reflector.

[0006] In the optical microphone described above, both the first and second optical components are curved reflectors.

[0007] In the optical microphone described above, the first optical device and the second optical device are confocal.

[0008] In the optical microphone described above, the light input section is optically coupled to the first optical device; the light receiving section is optically coupled to the first optical device and receives the light signal affected by the sound wave signal that passes through the first optical device from the resonant cavity.

[0009] In the optical microphone described above, the light input section is optically coupled to the first optical device; the light receiving section is optically coupled to the second optical device, and receives the light signal affected by the sound wave signal that passes through the second optical device from the resonant cavity.

[0010] In the optical microphone described above, the first optical device is a plane mirror or a plane reflective film, and the second optical device is a curved mirror.

[0011] In the optical microphone described above, the light input section is optically coupled to the first optical device; the light receiving section is optically coupled to the first optical device and receives the light signal affected by the sound wave signal that passes through the first optical device from the resonant cavity.

[0012] In the optical microphone described above, the first optical element and the second optical element are arranged in parallel.

[0013] In the optical microphone described above, the first optical element and the second optical element are housed in a single tube.

[0014] In the optical microphone described above, the first optical element and the second optical element are disposed on a glass substrate.

[0015] According to this invention, by configuring at least one of the first and second optical components constituting the resonant cavity for measuring sound waves as a curved reflector, the advantages of simple manufacturing process, low insertion loss, and high precision can be achieved. Specifically, according to this invention, the first reflecting surface of the resonant cavity (which can be curved or planar) can be attached to the output end of the collimator or directly plated onto the cross-section of the collimator, and the second reflector uses a curved mirror for beam focusing. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the first embodiment of the optical microphone probe of this utility model.

[0017] Figure 2 This is a schematic diagram of the second embodiment of the optical microphone probe in this utility model.

[0018] Figure 3 This is a schematic diagram of the third embodiment of the optical microphone probe in this utility model. Detailed Implementation

[0019] like Figure 1 As shown, this utility model discloses a first embodiment of an optical microphone. The optical microphone according to the first embodiment of this utility model includes an optical fiber 11, an optical fiber head 12, a lens 13, a sleeve 14, a first curved reflector 15, and a second curved reflector 16.

[0020] The laser beam travels through optical fiber 11 to a collimating optical lens composed of fiber optic head 12 and lens 13. This collimating lens couples the light wave into spatial light, which then illuminates a resonant cavity formed by a first curved mirror 15 and a second curved mirror 16, both of which are confocal. The reflected light wave from the resonant cavity is then coupled back into optical fiber 11 through the collimating lens formed by lens 13 and fiber optic head 12. The resonant cavity of the first curved mirror 15 and second curved mirror 16 is used for coupling of sound wave 92.

[0021] In this embodiment, the fiber optic head 12 and lens 13 are encapsulated in a sleeve 14. The first curved reflector 15 and the second curved reflector 16 are arranged parallel to each other. The first curved reflector 15 and the second curved reflector 16 can also be encapsulated in a sleeve, with holes provided on the sleeve for coupling the acoustic wave 92 into the resonant cavity 91. The sleeve can also be replaced with a glass substrate, and the corresponding optical components are fixed on the glass substrate.

[0022] The working principle of the optical microphone according to the first embodiment of this utility model is as follows: Light from the optical fiber 11 is coupled into spatial light through a collimating optical lens composed of the optical fiber head 12 and the lens 13. This spatial light passes through the first curved reflector 15 and enters the resonant cavity 91 composed of the first curved reflector 15 and the second curved reflector 16, and resonates in the resonant cavity 91 due to the reflection of the second curved reflector 16. When the light resonates in the resonant cavity 91 composed of the first curved reflector 15 and the second curved reflector 16, an external sound wave 92 acts on the light wave in the resonant cavity 91 and affects it. Therefore, the light resonating in the resonant cavity 91 carries the information of the sound wave 92. The light resonating in the resonant cavity 91 and affected by the external sound wave 92 can pass through the first curved reflector 15 and be received by the collimating optical lens composed of the optical fiber head 12 and the lens 13. By analyzing the received light signal, information related to the sound wave 92 can be obtained, which can be achieved by any known means.

[0023] like Figure 2 As shown, this utility model discloses a second embodiment of an optical microphone. The optical microphone according to the second embodiment includes an optical fiber 21, an optical fiber head 22, a lens 23, a sleeve 24, a first curved reflector 25, a second curved reflector 26, a lens 27, an optical fiber head 28, a sleeve 29, and an optical fiber 210.

[0024] The laser beam travels through optical fiber 21 to a collimating optical lens composed of fiber optic head 22 and lens 23. This collimating lens couples the light wave into spatial light, which then illuminates a resonant cavity formed by a first curved mirror 25 and a second curved mirror 26, both of which are confocal. The transmitted light wave from the resonant cavity is then coupled into optical fiber 210 via a collimating lens composed of lens 27 and fiber optic head 28. The resonant cavity of the first curved mirror 25 and the second curved mirror 26 is used for sound wave coupling.

[0025] In this embodiment, the fiber optic head 22 and lens 23 are encapsulated in sleeve 24, and lens 27 and fiber optic head 28 are encapsulated in sleeve 29. The first curved reflector 25 and the second curved reflector 26 are arranged parallel to each other. The first curved reflector 25 and the second curved reflector 26 can also be encapsulated in a sleeve, with holes provided on the sleeve for coupling the acoustic wave 92 into the resonant cavity 91. The sleeve can also be replaced with a glass substrate, and the corresponding optical components are fixed on the glass substrate. Although the first curved reflector 25 is shown as a separate component in the figure, it can be directly plated onto the cross-section of the collimator.

[0026] The working principle of the optical microphone according to the second embodiment of this utility model is as follows: Light from optical fiber 21 is coupled into spatial light through a collimating optical lens composed of optical fiber head 22 and lens 23. This spatial light enters the resonant cavity 91 composed of first curved reflector 25 and second curved reflector 26 after passing through first curved reflector 25, and resonates in the resonant cavity 91 through reflection by second curved reflector 26. When the light resonates in the resonant cavity 91 composed of first curved reflector 25 and second curved reflector 26, external sound wave 92 acts on the light wave in the resonant cavity 91 and affects it. Thus, the light resonating in the resonant cavity 91 carries the information of sound wave 92. The light resonating in the resonant cavity 91 and affected by external sound wave 92 can pass through second curved reflector 26 and be received by collimating optical lens composed of lens 27 and optical fiber head 28 and transmitted through optical fiber 210. By analyzing the received light signal, information related to sound wave 92 can be obtained, which can be achieved by any known means.

[0027] like Figure 3 As shown, this utility model discloses a third embodiment of an optical microphone. The optical microphone according to the third embodiment of this utility model is provided with an optical fiber 31, an optical fiber head 32, a sleeve 33, a lens 34, a reflective film 35, a sleeve 36, and a curved reflector 37.

[0028] The laser beam travels through optical fiber 31 to a collimating optical lens composed of fiber optic head 32 and lens 34. This collimating lens couples the light wave into spatial light, which then illuminates curved reflector 37. The light wave reflected back from curved reflector 37 is then coupled back into optical fiber 31 after passing through the collimating lens composed of lens 34 and fiber optic head 32. A partial reflective film 35 coated on the surface of lens 34, together with curved reflector 37, forms a resonant cavity 91. A hole is drilled in sleeve 36 to couple acoustic waves into the resonant cavity for acoustic measurement. Sleeve 36 can also be replaced with a glass substrate, on which the remaining components are fixed.

[0029] In this embodiment, the fiber optic connector 32 and the lens 34 are encapsulated in the sleeve 33. The reflective film 35 is arranged parallel to the curved reflector 37. The reflective film 35 can also be replaced by a reflector.

[0030] The working principle of the optical microphone according to the third embodiment of this utility model is as follows: Light from optical fiber 31 is coupled into spatial light through a collimating optical lens composed of optical fiber head 32 and lens 34. This spatial light passes through partial reflective film 35 and enters a resonant cavity 91 composed of partial reflective film 35 and curved reflector 37, and resonates in the resonant cavity 91 due to reflection by curved reflector 37. When the light resonates in the resonant cavity 91 composed of partial reflective film 35 and curved reflector 37, external sound waves 92 act on the light waves in the resonant cavity 91 and affect them. Therefore, the light resonating in the resonant cavity 91 carries information from the sound waves 92. The light resonating in the resonant cavity 91 and affected by external sound waves 92 can pass through partial reflective film 35 and be received by the collimating optical lens composed of optical fiber head 32 and lens 34. By analyzing the received light signal, information related to the sound waves 92 can be obtained, which can be achieved by any known means.

[0031] In this invention, a resonant cavity is formed by a hyperboloid or curved mirror and a partially reflective film coated on the surface of a Green lens, resulting in low insertion loss and high precision. This structure can be fabricated using microlenses, making it small and stable. Compared to membrane-less optical microphones based on FP etalons, the manufacturing process is simpler and easier to adjust. Furthermore, compared to membrane-less optical microphones based on FP etalons, it offers better integration and avoids instability caused by the large size and weight of the etalon structure and the probe's center of gravity being located at the head.

[0032] In this invention, a partially reflective film coated on the surface of the Green lens and a curved mirror constitute a resonant cavity. The sleeve in this structure can be made of glass, temperature-insensitive materials, or other similar materials. The sleeve can be circular, square, or other shapes. This resonant cavity can also be combined with Fabry-Perot, Michelson, and Mahzd interferometer structures to achieve sound wave measurement.

[0033] It should be noted that the utility model features of different exemplary embodiments of the present utility model can be arbitrarily combined with each other without departing from the protection scope of the present utility model, as long as these features are not mutually exclusive.

Claims

1. An optical microphone, characterized in that... include: A first optical device and a second optical device are positioned opposite each other, forming a resonant cavity between them. The optical signal transmitted in the resonant cavity can be affected by external acoustic signals. The light input section inputs light to the first optical device and further inputs light to the resonant cavity formed by the first and second optical devices. The optical receiver receives optical signals from the resonant cavity that are affected by acoustic signals. Among them, at least one of the first optical device and the second optical device is a curved reflector.

2. The optical microphone as described in claim 1, characterized in that: Both the first and second optical components are curved reflectors.

3. The optical microphone as described in claim 2, characterized in that: The first and second optical devices are confocal.

4. The optical microphone as described in claim 3, characterized in that: The light input section is optically coupled to the first optical device; the light receiving section is optically coupled to the first optical device, and receives the light signal affected by the acoustic signal that passes through the first optical device from the resonant cavity.

5. The optical microphone as described in claim 3, characterized in that: The light input section is optically coupled to the first optical device; the light receiving section is optically coupled to the second optical device, and receives the light signal affected by the acoustic signal that passes through the second optical device from the resonant cavity.

6. The optical microphone as described in claim 1, characterized in that: The first optical device is a plane mirror or a plane reflective film, and the second optical device is a curved mirror.

7. The optical microphone as described in claim 6, characterized in that: The light input section is optically coupled to the first optical device; the light receiving section is optically coupled to the first optical device, and receives the light signal affected by the acoustic signal that passes through the first optical device from the resonant cavity.

8. The optical microphone as described in any one of claims 1-7, characterized in that: The first and second optical components are arranged in parallel.

9. The optical microphone as described in any one of claims 1-7, characterized in that: The first optical device and the second optical device are housed in a single tube.

10. The optical microphone as described in any one of claims 1-7, characterized in that: The first optical device and the second optical device are disposed on a glass substrate.

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