CN113091882B - A dual-chamber device for detecting membrane surface vibration and its demodulation method - Google Patents
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Abstract
本发明公开了一种用于检测膜面振动的双腔装置及其解调方法,涉及光传感信息解调技术领域;包括激光器、光纤分束器、光环形器、光纤、双腔装置及光电探测器;激光器发出的激光经过光纤分束器分成两束光,光束通过光环形器传输到双腔装置,在双腔装置内光束照射在膜面上并反射回光纤,并与光纤端面的反射光发生干涉,干涉光通过光环形器传输到光电探测器上并转化为电信号;双腔装置结构使双腔输出的干涉信号呈一定的相位差状态,双腔装置内含有一种位移驱动结构,其促使光纤端面垂直膜面移动;通过对干涉光束转化的电信号采用椭圆拟合算法进行相位解调,分析计算出膜面振动的幅值变化;提高传感系统的灵敏度及稳定性。
The invention discloses a dual-cavity device for detecting membrane surface vibration and a demodulation method thereof, and relates to the technical field of optical sensing information demodulation; Photodetector: The laser emitted by the laser is divided into two beams of light through the fiber beam splitter, and the beam is transmitted to the dual-cavity device through the optical circulator. The reflected light interferes, and the interference light is transmitted to the photodetector through the optical circulator and converted into an electrical signal; the structure of the dual-cavity device makes the interference signal output by the dual-cavity in a certain phase difference state, and the dual-cavity device contains a displacement drive It promotes the movement of the fiber end face perpendicular to the membrane surface; by using ellipse fitting algorithm to demodulate the phase of the electrical signal converted by the interference beam, the amplitude change of the membrane vibration is analyzed and calculated; the sensitivity and stability of the sensing system are improved.
Description
技术领域technical field
本发明涉及光传感信息解调技术领域,尤其涉及的是一种用于检测膜面振动的双腔装置及其解调方法。The invention relates to the technical field of optical sensing information demodulation, in particular to a dual-cavity device for detecting vibration of a membrane surface and a demodulation method thereof.
背景技术Background technique
社会的发展需要对外界信息多层面、高深度的获取,各种传感器是我们获取外界信息的主要方式。光传感,特别是干涉型光传感以其高灵敏、抗电磁干扰及广泛的适用性而备受关注。在干涉型光传感中干涉臂的差异性往往会带来偏振衰落,FP腔干涉仪由于其同路传输及腔内各向同性介质的存在而具有抗路径干扰、抗偏振衰落的优点;针对干涉仪存在的相位衰落问题,学者们开发了各种相位解调技术,如相位生成载波法、外差法、3*3耦合器解调法等。针对FP腔干涉仪腔长较短的特点,双波长、三波长相位解调技术相继研究出来。The development of society requires multi-level and high-depth acquisition of external information. Various sensors are the main way for us to acquire external information. Optical sensing, especially interferometric optical sensing, has attracted much attention due to its high sensitivity, anti-electromagnetic interference and wide applicability. In interferometric optical sensing, the difference of the interference arms often brings polarization fading. The FP cavity interferometer has the advantages of anti-path interference and anti-polarization fading due to its co-channel transmission and the existence of isotropic medium in the cavity. For the phase fading problem of interferometers, scholars have developed various phase demodulation techniques, such as phase generation carrier method, heterodyne method, 3*3 coupler demodulation method, etc. In view of the short cavity length of the FP cavity interferometer, two-wavelength and three-wavelength phase demodulation technologies have been successively studied.
目前的双波长、三波长的FP腔干涉仪相位解调技术需要多个波长的激光,其所需激光器的成本较高、激光中心频率及功率的稳定要求较多;由于FP干涉仪的腔长受环境或大动态探测物理量的影响发生较大的改变,则相位解调效果会出现劣化、失真等不稳定现象。The current dual-wavelength and three-wavelength FP cavity interferometer phase demodulation technology requires multiple wavelengths of laser light, the required laser cost is high, and the laser center frequency and power stability requirements are more; due to the cavity length of the FP interferometer If there is a big change under the influence of the environment or the large dynamic detection physical quantity, the phase demodulation effect will be degraded, distorted and other unstable phenomena.
基于椭圆拟合算法的双腔装置膜面振动检测方法使用一种波长,通过双腔结构构建信号相位差,很好的满足了相关无缘相位解调技术对信号直流量消除,交流量归一化,以及相位差必须为正交的要求,具有明显的优势。然而,椭圆拟合算法要求两路信号的待测相位量必须大于π,否则其拟合的数据将不准确,这种情况限制了这种技术对小相位信号解调的使用。The double-cavity device membrane surface vibration detection method based on the ellipse fitting algorithm uses one wavelength and constructs the signal phase difference through the double-cavity structure, which well satisfies the elimination of the direct current of the signal and the normalization of the alternating current by the related unrelated phase demodulation technology. , and the requirement that the phase difference must be in quadrature, has obvious advantages. However, the ellipse fitting algorithm requires that the measured phase of the two signals must be greater than π, otherwise the fitted data will be inaccurate, which limits the use of this technique for small-phase signal demodulation.
发明内容SUMMARY OF THE INVENTION
本发明的目的在于提供一种用于检测膜面振动的双腔装置及其解调方法,本发明给出了检测膜面振动的双腔装置的构成以及双腔相位差的使用范围;可以降低传感装置实现的成本,提高传感系统的灵敏度及稳定性;同时给出了调制信号的频率及幅值大小的范围;通过调制信号的施加,扩展了基于椭圆拟合算法的相位解调方法的使用范围,使其可以在小相位信号解调工作。The purpose of the present invention is to provide a dual-cavity device for detecting the vibration of the membrane surface and a demodulation method thereof. The invention provides the structure of the dual-chamber device for detecting the vibration of the membrane surface and the use range of the phase difference of the dual-chamber; it can reduce the The realization cost of the sensing device improves the sensitivity and stability of the sensing system; at the same time, the frequency and amplitude range of the modulated signal is given; through the application of the modulated signal, the phase demodulation method based on the ellipse fitting algorithm is expanded range of use, making it possible to demodulate small-phase signals.
本发明的目的可以通过以下技术方案实现:The object of the present invention can be realized through the following technical solutions:
一种用于检测膜面振动的双腔装置,其特征在于,包括激光器、光纤分束器、光环形器、光纤、双腔装置及光电探测器;A dual-cavity device for detecting membrane surface vibration, characterized in that it includes a laser, an optical fiber beam splitter, an optical circulator, an optical fiber, a dual-cavity device and a photodetector;
该双腔装置的工作方法为:The working method of the dual-chamber device is as follows:
激光器发出的激光经过光纤分束器分成两束光,光束通过光环形器传输到双腔装置,在双腔装置内光束照射在膜面上并反射回光纤端面,并与光纤端面的反射光发生干涉,干涉光通过光环形器传输到光电探测器上并转化为电信号;双腔装置结构内光纤端面发射的平行光束照射在同一个膜面上,光纤端面在轴向上存在错位,该错位长度与激光器的波长匹配,使双腔装置输出的两路干涉信号呈一定的相位差;The laser emitted by the laser is divided into two beams by the fiber beam splitter, and the beam is transmitted to the dual-cavity device through the optical circulator. interference, the interference light is transmitted to the photodetector through the optical circulator and converted into an electrical signal; the parallel light beam emitted by the fiber end face in the double cavity device structure is irradiated on the same film surface, and the fiber end face is dislocated in the axial direction. The length matches the wavelength of the laser, so that the two interference signals output by the dual-cavity device have a certain phase difference;
双腔装置内含有一个固定在基台上的位移驱动器,所述位移驱动器促使光纤端面垂直于膜面移动;通过对干涉光束转化的电信号采用相位解调算法,分析计算出膜面振动的幅值。The dual-cavity device contains a displacement driver fixed on the base, and the displacement driver causes the fiber end face to move perpendicular to the membrane surface; the phase demodulation algorithm is applied to the electrical signal converted by the interference beam, and the amplitude of the membrane vibration is analyzed and calculated. value.
进一步地,所述激光器为单波长的窄线宽激光器。Further, the laser is a single-wavelength narrow linewidth laser.
进一步地,所述双腔装置由光纤端面与膜面构成,光纤端面发射的双光束照射在同一膜面上并沿原光路反射回光纤端面,同一双腔装置中存在两个FP腔。Further, the dual-cavity device is composed of a fiber end face and a membrane surface. The double beams emitted by the fiber end face are irradiated on the same membrane surface and reflected back to the fiber end face along the original optical path. There are two FP cavities in the same dual-cavity device.
进一步地,光纤端面在轴向上的错位长度与特定的波长匹配,使双腔装置输出的两路干涉信号呈一定的相位差,且此相位差不等于π或其整数倍。Further, the axial dislocation length of the fiber end face is matched with a specific wavelength, so that the two channels of interference signals output by the dual-cavity device have a certain phase difference, and the phase difference is not equal to π or its integer multiples.
进一步地,所述位移驱动器驱动两根光纤沿垂直于膜面方向以一定频率振动,其振动幅值所达到的调制信号相位变化大于π,其频率处于所检测膜面振动频带之外;Further, the displacement driver drives the two optical fibers to vibrate at a certain frequency along the direction perpendicular to the membrane surface, and the phase change of the modulation signal reached by its vibration amplitude is greater than π, and its frequency is outside the vibration frequency band of the detected membrane surface;
本发明提供的一种用于检测膜面振动的双腔装置,给出了检测膜面振动的双腔装置的构成以及双腔相位差的使用范围;可以降低传感装置实现的成本,提高传感系统的灵敏度及稳定性;The invention provides a dual-chamber device for detecting membrane surface vibration, and provides the structure of the dual-chamber device for detecting membrane surface vibration and the application range of the dual-chamber phase difference; the realization cost of the sensing device can be reduced, and the transmission rate can be improved. The sensitivity and stability of the sensor system;
进一步地,一种用于检测膜面振动的双腔装置的解调方法,包括如下步骤:Further, a method for demodulating a dual-chamber device for detecting vibration of the membrane surface, comprising the steps of:
各干涉仪输出信号为:The output signal of each interferometer is:
其中,A1与A2为干涉信号的直流分量,B1与B2为干涉信号的条纹对比度,是腔长为L1的FP干涉仪的初始相位,β是两个干涉仪的相位差,θt为待测相位量;St为膜面在FP腔轴向上的位移,Mt为双腔装置中位移驱动器施加的振动调制,n为腔介质光折射率,λ0为光源的波长;Among them, A 1 and A 2 are the DC components of the interference signal, B 1 and B 2 are the fringe contrasts of the interference signal, is the initial phase of the FP interferometer with cavity length L1, β is the phase difference between the two interferometers, θ t is the phase to be measured; S t is the displacement of the membrane surface in the axial direction of the FP cavity, and M t is the double cavity The vibration modulation applied by the displacement driver in the device, n is the refractive index of the cavity medium, and λ 0 is the wavelength of the light source;
将等式(1)改写成下式Rewrite equation (1) into the following equation
椭圆方程可以表达为The ellipse equation can be expressed as
I1 2+CI2I1+DI2 2+EI1+FI2+H=0. (3)I 1 2 +CI 2 I 1 +DI 2 2 +EI 1 +FI 2 +H=0. (3)
对比等式(2)与(3),可以得到Comparing equations (2) and (3), we can get
等式(1)中的参数A1,A2,B1,B2和β,可以结合等式(4)计算得到The parameters A1, A2, B1, B2 and β in equation (1) can be calculated in combination with equation (4)
一对含有待测相位信息θt的正交信号可以表达为A pair of quadrature signals containing the phase information to be measured θ t can be expressed as
通过反正切算法,可以得到θt,通过滤波器滤除调制信号的频率信号Mt,进而由等式(1)计算出膜面的位移St。本发明给出了调制信号的频率及幅值大小的范围;同时调制信号的施加,扩展了基于椭圆拟合算法的相位解调方法的使用范围,使其可以在小相位信号解调工作。Through the arctangent algorithm, θ t can be obtained, the frequency signal M t of the modulation signal is filtered out by a filter, and then the displacement S t of the membrane surface is calculated by equation (1). The invention provides the range of the frequency and amplitude of the modulated signal; at the same time, the application of the modulated signal expands the use range of the phase demodulation method based on the ellipse fitting algorithm, so that it can work in small-phase signal demodulation.
本发明的有益效果:Beneficial effects of the present invention:
1、本发明中激光器发出的激光经过光纤分束器分成两束光,光束通过光环形器传输到双腔装置,在双腔装置内光束照射在膜面上并反射回光纤端面,并与光纤端面的反射光发生干涉,干涉光通过光环形器传输到光电探测器上并转化为电信号;双腔装置结构内光纤端面发射的平行光束照射在同一个膜面上,光纤端面在轴向上存在错位,该错位长度与激光器的波长匹配,使双腔装置输出的两路干涉信号呈一定的相位差;双腔装置内含有一个固定在基台上的位移驱动器,所述位移驱动器促使光纤端面垂直于膜面移动;通过对干涉光束转化的电信号采用相位解调算法,分析计算出膜面振动的幅值;本发明给出了检测膜面振动的双腔装置的构成以及双腔相位差的使用范围;可以降低传感装置实现的成本,提高传感系统的灵敏度及稳定性;1. In the present invention, the laser emitted by the laser is divided into two beams of light through the fiber beam splitter, and the beam is transmitted to the dual-cavity device through the optical circulator. The reflected light from the end face interferes, and the interference light is transmitted to the photodetector through the optical circulator and converted into an electrical signal; the parallel beam emitted by the end face of the fiber in the dual-cavity device structure is irradiated on the same film surface, and the end face of the fiber is in the axial direction. There is dislocation, and the dislocation length matches the wavelength of the laser, so that the two-way interference signals output by the dual-cavity device have a certain phase difference; the dual-cavity device contains a displacement driver fixed on the base, and the displacement driver promotes the end face of the fiber. It moves perpendicular to the membrane surface; the phase demodulation algorithm is used for the electrical signal converted by the interference beam to analyze and calculate the amplitude of the membrane surface vibration; the invention provides the structure of the double-cavity device for detecting the membrane surface vibration and the phase difference of the double-cavity It can reduce the cost of sensing device implementation and improve the sensitivity and stability of the sensing system;
2、本发明还提供了一种用于检测膜面振动的双腔装置的解调方法,通过对干涉光束转化的电信号采用基于椭圆拟合算法,分析计算出膜面振动幅值的变化,本发明给出了调制信号的频率及幅值大小的范围;同时调制信号的施加,扩展了基于椭圆拟合算法的相位解调方法的使用范围,使其可以在小相位信号解调工作。2. The present invention also provides a demodulation method for a dual-cavity device for detecting the vibration of the membrane surface. By using an ellipse-based fitting algorithm on the electrical signal converted by the interference beam, the change of the vibration amplitude of the membrane surface is analyzed and calculated, The invention provides the frequency and amplitude range of the modulated signal; at the same time, the application of the modulated signal expands the use range of the phase demodulation method based on the ellipse fitting algorithm, so that it can work in small-phase signal demodulation.
附图说明Description of drawings
为了更清楚地说明本发明实施例或现有技术中的技术方案,下面将对实施例或现有技术描述中所需要使用的附图作简单地介绍,显而易见地,下面描述中的附图仅仅是本发明的一些实施例,对于本领域普通技术人员来讲,在不付出创造性劳动的前提下,还可以根据这些附图获得其他的附图。In order to illustrate the embodiments of the present invention or the technical solutions in the prior art more clearly, the following briefly introduces the accompanying drawings that are used in the description of the embodiments or the prior art. Obviously, the drawings in the following description are only These are some embodiments of the present invention. For those of ordinary skill in the art, other drawings can also be obtained from these drawings without creative efforts.
图1是本发明的一种用于检测膜面振动的双腔装置及解调系统的组成图。FIG. 1 is a composition diagram of a dual-chamber device and a demodulation system for detecting membrane surface vibration according to the present invention.
图2是本发明中的双腔装置的结构示意图。FIG. 2 is a schematic structural diagram of the dual-chamber device in the present invention.
图3是本发明加调制与不加调制下对膜面振动解调数据对比图。FIG. 3 is a comparison diagram of the demodulation data of the membrane surface vibration under the present invention with and without modulation.
图4是本发明加调制与不加调制下对膜面振动解调误差对比图。FIG. 4 is a comparison diagram of the demodulation error of the membrane surface vibration with and without modulation according to the present invention.
具体实施方式Detailed ways
下面将对本发明实施例中的技术方案进行清楚、完整地描述,显然,所描述的实施例仅仅是本发明一部分实施例,而不是全部的实施例。基于本发明中的实施例,本领域普通技术人员在没有作出创造性劳动前提下所获得的所有其它实施例,都属于本发明保护的范围。The technical solutions in the embodiments of the present invention will be described clearly and completely below. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.
参见图1至图4,本实施例公开了一种用于检测膜面振动的双腔装置,包括激光器、光纤分束器、光环行器、若干光纤、双腔装置以及光电探测器;Referring to FIGS. 1 to 4 , this embodiment discloses a dual-cavity device for detecting membrane surface vibration, including a laser, a fiber beam splitter, an optical circulator, several optical fibers, a dual-cavity device, and a photodetector;
激光器发出的激光经过光纤分束器分成两束光,光束通过光环形器传输到双腔装置,在双腔装置内光束照射在膜面上并反射回光纤端面,而后与光纤端面的反射光发生干涉,干涉光通过光环形器传输到光电探测器上并转化为电信号;The laser emitted by the laser is divided into two beams by the fiber beam splitter, and the beam is transmitted to the dual-cavity device through the optical circulator. Interference, the interference light is transmitted to the photodetector through the optical circulator and converted into an electrical signal;
双腔装置内光纤端面发射的平行光束照射在同一个膜面上,光纤端面在光纤轴向上存在一定长度的错位,此错位长度与激光器波长匹配,使两路干涉信号形成一定的相位差;The parallel beam emitted by the fiber end face in the dual-cavity device is irradiated on the same film surface, and the fiber end face has a certain length of dislocation in the fiber axis. This dislocation length matches the wavelength of the laser, so that the two interference signals form a certain phase difference;
双腔装置内含有一个固定在基台上的位移驱动器,所述位移驱动器促使光纤端面垂直于膜面移动;通过对干涉光束转化的电信号采用相位解调算法,分析计算出膜面振动的幅值;两根光纤固定在位移驱动器上,两根光纤不与基台固定;The dual-cavity device contains a displacement driver fixed on the base, and the displacement driver causes the fiber end face to move perpendicular to the membrane surface; the phase demodulation algorithm is applied to the electrical signal converted by the interference beam, and the amplitude of the membrane vibration is analyzed and calculated. value; two optical fibers are fixed on the displacement driver, and two optical fibers are not fixed with the base;
使用压电陶瓷作为位移驱动器,驱动两根光纤沿垂直膜面方向以一定频率振动,其振动幅值所达到调制信号相位变化应大于π,其频率应处于所检测膜面振动频带之外;所述激光器为单波长的窄线宽激光器。Use piezoelectric ceramics as the displacement driver to drive the two optical fibers to vibrate at a certain frequency along the direction perpendicular to the membrane surface. The phase change of the modulation signal achieved by the vibration amplitude should be greater than π, and its frequency should be outside the vibration frequency band of the detected membrane surface. The laser is a single-wavelength narrow linewidth laser.
所述双腔装置由光纤端面与膜面构成,光纤端面发射的双光束照射在同一膜面上并沿原光路反射回光纤端面,同一双腔装置中存在两个FP腔;The dual-cavity device is composed of an optical fiber end face and a membrane surface, the double beams emitted by the optical fiber end face are irradiated on the same membrane surface and reflected back to the optical fiber end face along the original optical path, and there are two FP cavities in the same dual-cavity device;
光纤端面在轴向上的错位长度与特定的波长匹配,使双腔装置输出的两路干涉信号呈一定的相位差,且此相位差不等于π或其整数倍;本发明给出了检测膜面振动的双腔装置的构成以及双腔相位差的使用范围;可以降低传感装置实现的成本,提高传感系统的灵敏度及稳定性;The dislocation length of the fiber end face in the axial direction is matched with a specific wavelength, so that the two-way interference signals output by the dual-cavity device have a certain phase difference, and the phase difference is not equal to π or its integer multiples; the invention provides a detection film. The composition of the double-cavity device with surface vibration and the use range of the double-cavity phase difference can reduce the cost of the sensing device and improve the sensitivity and stability of the sensing system;
本实施例还公开了用于上述检测膜面振动的双腔装置的解调方法,通过对干涉光束转化的电信号采用基于椭圆拟合算法,分析计算出膜面振动幅值的变化,包括如下步骤:This embodiment also discloses a demodulation method for the above-mentioned dual-cavity device for detecting the vibration of the membrane surface. By using an ellipse fitting algorithm based on the electrical signal converted from the interference beam, the change of the vibration amplitude of the membrane surface is analyzed and calculated, including the following: step:
各干涉仪输出信号为:The output signal of each interferometer is:
其中,A1与A2为干涉信号的直流分量,B1与B2为干涉信号的条纹对比度,是腔长为L1的FP干涉仪的初始相位,β是两个干涉仪的相位差,θt为待测相位量,St为膜面在FP腔轴向上的位移,Mt为双腔装置中施加的振动调制,n为腔介质光折射率,λ0为光源的波长。Among them, A 1 and A 2 are the DC components of the interference signal, B 1 and B 2 are the fringe contrasts of the interference signal, is the initial phase of the FP interferometer with the cavity length L1, β is the phase difference between the two interferometers, θ t is the phase to be measured, S t is the displacement of the membrane surface in the axial direction of the FP cavity, and M t is the double cavity The vibration modulation applied in the device, n is the light refractive index of the cavity medium, and λ 0 is the wavelength of the light source.
将等式(1)改写成下式Rewrite equation (1) into the following equation
一般的椭圆方程可以表达为The general ellipse equation can be expressed as
I1 2+CI2I1+DI2 2+EI1+FI2+H=0. (3)I 1 2 +CI 2 I 1 +DI 2 2 +EI 1 +FI 2 +H=0. (3)
对比等式(2)与(3),可以得到Comparing equations (2) and (3), we can get
等式(1)中的参数A1,A2,B1,B2和β,可以由等式(4)得到The parameters A1, A2, B1, B2 and β in equation (1) can be obtained from equation (4)
一对含有待测相位信息θt的正交信号可以表达A pair of quadrature signals containing the phase information to be measured θ t can be expressed
通过反正切算法,可以得到θt,通过滤波器滤除调制信号所在的频率信号Mt,进而由等式(1)算出膜面的位移St;本发明给出了调制信号的频率及幅值大小的范围;同时调制信号的施加,扩展了基于椭圆拟合算法的相位解调方法的使用范围,使其可以在小相位信号解调工作。Through the arctangent algorithm, θ t can be obtained, the frequency signal M t where the modulation signal is located is filtered out by the filter, and then the displacement S t of the membrane surface is calculated by equation (1); the present invention provides the frequency and amplitude of the modulation signal. At the same time, the application of the modulation signal expands the use range of the phase demodulation method based on the ellipse fitting algorithm, so that it can work in the demodulation of small phase signals.
针对上述装置及解调算法,通过实验验证了可行性以及调制设置的有效性。如图3-4所示,上述装置及解调算法能够用于膜面振动的检测,并且增加调制后,装置及解调算法对膜面振动检测的性能及误差有明显的优化。For the above device and demodulation algorithm, the feasibility and the effectiveness of the modulation setting are verified by experiments. As shown in Figure 3-4, the above device and demodulation algorithm can be used for the detection of membrane surface vibration, and after adding modulation, the device and demodulation algorithm can significantly optimize the performance and error of membrane surface vibration detection.
本发明的工作原理是:The working principle of the present invention is:
一种用于检测膜面振动的双腔装置及其解调方法,在工作时,激光器发出的激光经过光纤分束器分成两束光,光束通过光环形器传输到双腔装置,在双腔装置内光束照射在膜面上并反射回光纤端面,并与光纤端面的反射光发生干涉,干涉光通过光环形器传输到光电探测器上并转化为电信号;双腔装置结构内光纤端面发射的平行光束照射在同一个膜面上,光纤端面在轴向上存在错位,该错位长度与激光器的波长匹配,使双腔装置输出的两路干涉信号呈一定的相位差;双腔装置内含有一个固定在基台上的位移驱动器,所述位移驱动器促使光纤端面垂直于膜面移动;通过对干涉光束转化的电信号采用相位解调算法,分析计算出膜面振动的幅值;其振动幅值所达到的调制信号相位变化大于π,其频率处于所检测膜面振动频带之外;本发明给出了检测膜面振动的双腔装置的构成以及双腔相位差的使用范围;可以降低传感装置实现的成本,提高传感系统的灵敏度及稳定性;A dual-cavity device for detecting membrane surface vibration and a demodulation method thereof. During operation, laser light emitted by a laser is divided into two beams of light through an optical fiber beam splitter, and the beams are transmitted to the dual-cavity device through an optical circulator. The light beam in the device is irradiated on the film surface and reflected back to the end face of the fiber, and interferes with the reflected light from the end face of the fiber. The interference light is transmitted to the photodetector through the optical circulator and converted into an electrical signal; the end face of the fiber in the double-cavity device structure emits The parallel beam of the laser is irradiated on the same film surface, and the fiber end face is dislocated in the axial direction. The dislocation length matches the wavelength of the laser, so that the two-way interference signals output by the dual-cavity device have a certain phase difference; the dual-cavity device contains A displacement driver fixed on the base, the displacement driver causes the fiber end face to move perpendicular to the membrane surface; the phase demodulation algorithm is applied to the electrical signal converted by the interference beam, and the amplitude of the membrane surface vibration is analyzed and calculated; its vibration amplitude The phase change of the modulation signal achieved by the value is greater than π, and its frequency is outside the vibration frequency band of the detected membrane surface; the invention provides the structure of the double-cavity device for detecting the vibration of the membrane surface and the use range of the double-cavity phase difference; it can reduce the transmission frequency. The cost of sensing device implementation is improved, and the sensitivity and stability of the sensing system are improved;
同时通过对干涉光束转化的电信号采用基于椭圆拟合算法,分析计算出膜面振动幅值的变化,本发明给出了调制信号的频率及幅值大小的范围;同时调制信号的施加,扩展了基于椭圆拟合算法的相位解调方法的使用范围,使其可以在小相位信号解调工作。At the same time, by using an ellipse fitting algorithm based on the electrical signal converted by the interference beam, the change of the vibration amplitude of the membrane surface is analyzed and calculated, and the invention provides the frequency and amplitude range of the modulation signal; The application range of the phase demodulation method based on the ellipse fitting algorithm is introduced, so that it can work in the demodulation of small phase signals.
在本说明书的描述中,参考术语“一个实施例”、“示例”、“具体示例”等的描述意指结合该实施例或示例描述的具体特征、结构、材料或者特点包含于本发明的至少一个实施例或示例中。在本说明书中,对上述术语的示意性表述不一定指的是相同的实施例或示例。而且,描述的具体特征、结构、材料或者特点可以在任何的一个或多个实施例或示例中以合适的方式结合。In the description of this specification, description with reference to the terms "one embodiment," "example," "specific example," etc. means that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one aspect of the present invention. in one embodiment or example. In this specification, schematic representations of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the particular features, structures, materials or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.
以上内容仅仅是对本发明结构所作的举例和说明,所属本技术领域的技术人员对所描述的具体实施例做各种各样的修改或补充或采用类似的方式替代,只要不偏离发明的结构或者超越本权利要求书所定义的范围,均应属于本发明的保护范围。The above content is only an example and description of the structure of the present invention, and those skilled in the art can make various modifications or supplements to the specific embodiments described or replace them in similar ways, as long as they do not deviate from the structure of the invention or Anything beyond the scope defined by the claims shall belong to the protection scope of the present invention.
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