WO2019128827A1 - 一种调频连续波激光干涉光纤位移传感器及其位移检测方法 - Google Patents

一种调频连续波激光干涉光纤位移传感器及其位移检测方法 Download PDF

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WO2019128827A1
WO2019128827A1 PCT/CN2018/122245 CN2018122245W WO2019128827A1 WO 2019128827 A1 WO2019128827 A1 WO 2019128827A1 CN 2018122245 W CN2018122245 W CN 2018122245W WO 2019128827 A1 WO2019128827 A1 WO 2019128827A1
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fiber
mirror
continuous wave
wave laser
single mode
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PCT/CN2018/122245
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English (en)
French (fr)
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郑刚
刘卫国
高明
陈海滨
张雄星
王伟
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西安工业大学
郑刚
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Priority to US16/957,390 priority Critical patent/US20200318949A1/en
Publication of WO2019128827A1 publication Critical patent/WO2019128827A1/zh

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    • GPHYSICS
    • G01MEASURING; TESTING
    • G01BMEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
    • G01B11/00Measuring arrangements characterised by the use of optical techniques
    • G01B11/14Measuring arrangements characterised by the use of optical techniques for measuring distance or clearance between spaced objects or spaced apertures
    • GPHYSICS
    • G01MEASURING; TESTING
    • G01BMEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
    • G01B11/00Measuring arrangements characterised by the use of optical techniques
    • G01B11/02Measuring arrangements characterised by the use of optical techniques for measuring length, width or thickness
    • G01B11/026Measuring arrangements characterised by the use of optical techniques for measuring length, width or thickness by measuring distance between sensor and object
    • GPHYSICS
    • G01MEASURING; TESTING
    • G01BMEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
    • G01B11/00Measuring arrangements characterised by the use of optical techniques
    • G01B11/02Measuring arrangements characterised by the use of optical techniques for measuring length, width or thickness
    • GPHYSICS
    • G01MEASURING; TESTING
    • G01BMEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
    • G01B11/00Measuring arrangements characterised by the use of optical techniques
    • G01B11/08Measuring arrangements characterised by the use of optical techniques for measuring diameters
    • G01B11/10Measuring arrangements characterised by the use of optical techniques for measuring diameters of objects while moving
    • G01B11/105Measuring arrangements characterised by the use of optical techniques for measuring diameters of objects while moving using photoelectric detection means
    • GPHYSICS
    • G01MEASURING; TESTING
    • G01BMEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
    • G01B9/00Measuring instruments characterised by the use of optical techniques
    • G01B9/02Interferometers
    • G01B9/02001Interferometers characterised by controlling or generating intrinsic radiation properties
    • G01B9/02002Interferometers characterised by controlling or generating intrinsic radiation properties using two or more frequencies
    • G01B9/02003Interferometers characterised by controlling or generating intrinsic radiation properties using two or more frequencies using beat frequencies
    • GPHYSICS
    • G01MEASURING; TESTING
    • G01BMEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
    • G01B9/00Measuring instruments characterised by the use of optical techniques
    • G01B9/02Interferometers
    • G01B9/02001Interferometers characterised by controlling or generating intrinsic radiation properties
    • G01B9/02002Interferometers characterised by controlling or generating intrinsic radiation properties using two or more frequencies
    • G01B9/02004Interferometers characterised by controlling or generating intrinsic radiation properties using two or more frequencies using frequency scans
    • GPHYSICS
    • G01MEASURING; TESTING
    • G01BMEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
    • G01B9/00Measuring instruments characterised by the use of optical techniques
    • G01B9/02Interferometers
    • G01B9/02015Interferometers characterised by the beam path configuration
    • G01B9/02023Indirect probing of object, e.g. via influence on cavity or fibre
    • GPHYSICS
    • G01MEASURING; TESTING
    • G01BMEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
    • G01B9/00Measuring instruments characterised by the use of optical techniques
    • G01B9/02Interferometers
    • G01B9/02055Reduction or prevention of errors; Testing; Calibration
    • G01B9/02056Passive reduction of errors
    • G01B9/02057Passive reduction of errors by using common path configuration, i.e. reference and object path almost entirely overlapping
    • GPHYSICS
    • G01MEASURING; TESTING
    • G01SRADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
    • G01S17/00Systems using the reflection or reradiation of electromagnetic waves other than radio waves, e.g. lidar systems
    • G01S17/02Systems using the reflection of electromagnetic waves other than radio waves
    • G01S17/06Systems determining position data of a target
    • G01S17/08Systems determining position data of a target for measuring distance only
    • G01S17/32Systems determining position data of a target for measuring distance only using transmission of continuous waves, whether amplitude-, frequency-, or phase-modulated, or unmodulated
    • G01S17/34Systems determining position data of a target for measuring distance only using transmission of continuous waves, whether amplitude-, frequency-, or phase-modulated, or unmodulated using transmission of continuous, frequency-modulated waves while heterodyning the received signal, or a signal derived therefrom, with a locally-generated signal related to the contemporaneously transmitted signal
    • GPHYSICS
    • G01MEASURING; TESTING
    • G01SRADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
    • G01S7/00Details of systems according to groups G01S13/00, G01S15/00, G01S17/00
    • G01S7/48Details of systems according to groups G01S13/00, G01S15/00, G01S17/00 of systems according to group G01S17/00
    • G01S7/481Constructional features, e.g. arrangements of optical elements
    • G01S7/4811Constructional features, e.g. arrangements of optical elements common to transmitter and receiver
    • G01S7/4812Constructional features, e.g. arrangements of optical elements common to transmitter and receiver transmitted and received beams following a coaxial path
    • GPHYSICS
    • G01MEASURING; TESTING
    • G01SRADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
    • G01S7/00Details of systems according to groups G01S13/00, G01S15/00, G01S17/00
    • G01S7/48Details of systems according to groups G01S13/00, G01S15/00, G01S17/00 of systems according to group G01S17/00
    • G01S7/481Constructional features, e.g. arrangements of optical elements
    • G01S7/4818Constructional features, e.g. arrangements of optical elements using optical fibres

Definitions

  • the invention relates to the field of displacement sensing technology, in particular to a frequency modulation continuous wave laser interference fiber displacement sensor.
  • Displacement sensing is an extremely important measurement and testing technology in the scientific, industrial and military fields.
  • Optical displacement sensing technology is especially valued due to its high precision, non-contact, and immunity to electromagnetic interference.
  • the fiber displacement sensing technology has the advantages of small size, light weight, compact structure and flexible form.
  • a variety of fiber displacement sensing technologies have been reported, mainly including two types, one is an intensity modulated fiber displacement sensor, and the other is a laser interference type fiber displacement sensor.
  • the intensity modulated fiber displacement sensor is simpler in detection method and signal processing, but has the disadvantages of low precision, poor stability, non-linear response, and small measurement range.
  • the laser interferometric fiber displacement sensor using the traditional optical zero-beat interference technology can achieve very high measurement accuracy, but its measurement accuracy depends on the stability of the laser wavelength, and it is difficult to have the fringe counting problem due to the interference signal being a static signal. Get high-precision displacement sensing with large dynamic range.
  • the present application provides a frequency modulated continuous wave laser interference fiber displacement sensor and a displacement detecting method thereof, which solve the problems in the prior art.
  • An FM continuous wave laser interference fiber displacement sensor comprises a single mode frequency modulated continuous wave laser and at least one optical fiber displacement sensing system connected to the single mode frequency modulated continuous wave laser;
  • the optical fiber displacement sensing system comprises an optical circulator , a fiber collimator, a partial mirror, a cooperative mirror, and a photodetector;
  • the single mode frequency modulated continuous wave laser is connected to an incident port of the optical circulator through a single mode fiber or a fiber coupler, and the optical circulator is adjacent to the exit
  • the port is connected to the fiber collimator through a single mode fiber, the third port of the optical circulator is connected to the photodetector, a partial mirror is arranged after the fiber collimator, a cooperative mirror is arranged after the partial mirror, and the cooperative mirror is attached to the Measure the surface of the target object and move it with it.
  • the single mode frequency modulated continuous wave laser is welded to the incident port of the optical circulator or connected by a flange through a single mode fiber or a fiber coupler.
  • the partial mirror is attached to the exit end face of the fiber collimator by adhesive or mechanical fixing.
  • exit mirror surface of the fiber collimator is plated with a partially reflective portion transmissive optical film material to form the partial mirror.
  • the fiber collimator uses a G-lens fiber collimator, a spherical lens (C-lens) fiber collimator or an aspheric fiber collimator.
  • the cooperative mirror selects a partial mirror or a total reflection mirror.
  • the cooperative mirror is a total reflection mirror
  • a dielectric mirror or a metal mirror is selected.
  • the displacement detecting method is as follows: the frequency modulated continuous wave emitted by the single mode frequency modulated continuous wave laser is coupled to the incident port of the optical circulator by a single mode fiber or a fiber coupler, adjacent to the optical circulator The output of the exit port is then coupled out through the fiber collimator. A portion of the outgoing light is reflected by the partial mirror, and the other part of the emitted light is transmitted by the partial mirror and illuminates the mirror surface of the cooperative mirror moving with the object to be tested. The mirror reflects the light back to the partial mirror and interferes with the reflected light of the partial mirror to form a beat signal.
  • the beat signal is coupled back to the single mode fiber by the fiber collimator and incident on the optical circulator, and is optically looped.
  • the third port of the device exits and is converted into an electrical signal by a single mode fiber coupled to the photodetector, and the displacement information of the target object can be obtained by processing and analyzing the electrical signal.
  • the invention greatly reduces the loss of the test laser in the optical path, improves the utilization efficiency of the laser energy, eliminates the influence of the feedback light on the light source, and significantly improves the signal-to-noise ratio of the FM continuous wave laser interference signal, which can be In the large range of centimeters or more, the measurement accuracy of ⁇ 10nm is obtained, and the precision optical fiber displacement sensing measurement with large dynamic range is realized.
  • the invention constitutes an all-fiber type frequency modulation continuous wave laser interference fiber displacement sensing optical path, which has compact structure and stable performance.
  • Fig. 1 is a schematic view showing the structure of a first embodiment of the present invention.
  • Figure 2 is a graph showing the relationship between the initial phase shift of the beat signal and the displacement of the target to be measured during the displacement sensing measurement.
  • Fig. 3 is a schematic view showing the structure of a second embodiment of the present invention.
  • a 1-mode frequency modulated continuous wave laser a 2-optical circulator, a 3-fiber collimator, a 4-part mirror, a 5-cooperative mirror, a 6-photodetector, and a 7-fiber coupler.
  • the frequency modulated continuous wave laser interference fiber displacement sensor of the present invention comprises a single mode frequency modulated continuous wave laser 1 and at least one fiber displacement sensing system connected to the single mode frequency modulated continuous wave laser;
  • the fiber displacement sensing system comprises an optical circulator 2; a collimator 3, a partial mirror 4, a cooperative mirror 5 and a photodetector 6;
  • the single mode FM continuous wave laser 1 is connected to an incident port of the optical circulator 2 through a single mode fiber or fiber coupler 7, optical ring
  • the adjacent exit port of the device 2 is connected to the fiber collimator 3 through a single mode fiber, the third port of the optical circulator 2 is connected to the photodetector 6, and the partial mirror 4 is disposed behind the fiber collimator 3, and the partial mirror 4 is provided.
  • the cooperative mirror 5 is disposed, and the cooperative mirror 5 moves together with the target object to be tested.
  • the basic principle of the frequency-modulated continuous wave laser interference fiber displacement sensor of the invention is that: using the frequency modulation continuous wave laser interference technology, a dynamic beat frequency signal can be naturally generated, and the linear relationship between the initial phase of the dynamic signal and the relative displacement of the object can be utilized. A measure of the relative displacement of the object is achieved.
  • the fiber displacement sensor has the advantages of high measurement accuracy, discriminable displacement direction, and large measurement dynamic range. Therefore, the measurement accuracy and dynamic range of the fiber displacement sensor based on the frequency-modulated continuous wave laser interference are higher than the conventional laser interference type fiber displacement sensor.
  • Embodiment 1 provides a single-channel FM continuous wave laser interference fiber displacement sensor, that is, a single mode FM continuous wave laser is connected to only one fiber displacement sensing system; specifically: single mode frequency modulated continuous wave
  • the laser 1 is connected to one port of the optical circulator 2 by a single mode fiber, which in the present embodiment is connected by fusion; however, in other embodiments, they may also be flanged.
  • the adjacent exit ports of the optical circulator 2 are connected to the pigtails of the fiber collimator 3 through a single mode fiber, and the third port of the optical circulator 2 is connected to the pigtails of the photodetector 6 through a single mode fiber.
  • the partial mirror 4 is disposed at the rear end of the fiber collimator.
  • the partial mirror 4 is placed as a separate device behind the fiber collimator 3; however, in other embodiments, the partial mirror 4 may also pass through the glue.
  • the function of the partial mirror 4 is achieved by attaching it to the exit end face of the fiber collimator 3 in a viscous or mechanically fixed manner, or by plating a partially reflective portion of the optical fiber material on the exit face of the fiber collimator 3.
  • a single-mode frequency modulated continuous wave laser 1 is used to transmit a frequency-modulated frequency-modulated continuous wave laser, which is coupled to an input port of the optical circulator through a fiber, and is output from an adjacent exit port of the optical circulator 2,
  • the output light is incident on the fiber collimator 3 via the single-mode fiber, and the partial beam 4 is reflected by the fiber collimator 3, and part of the light is reflected as reference light, and part of the light is transmitted and then irradiated to the moving object to be tested.
  • the cooperative mirror 5 of the surface is reflected, as the signal light, the signal light returns to the original path, and the reference light is superimposed and interfered on the reflecting surface of the partial mirror 4 to form a beat signal, and the beat signal is coupled back to the fiber by the fiber collimator 3.
  • the optical path is incident on the original exit port of the optical circulator 2, exits from the third port of the optical circulator 2, is received by the photodetector 6, and is converted into an electrical signal.
  • I 0 I 1 + I 2 , where V is the contrast of the beat signal, and ⁇ is the optical frequency modulation width, ⁇ m is the frequency of the modulation signal, c is the speed of light, t is time, ⁇ 0 is the wavelength of the light wave in vacuum, ⁇ b is the frequency of the beat signal, and ⁇ b0 is the initial phase of the beat signal.
  • OPD is the optical path difference between reference light and signal light
  • n is the refractive index of air (n ⁇ 1)
  • d is the distance between the reflecting surface of the partial mirror 4 and the reflecting surface of the cooperative mirror [5] attached to the surface of the moving object of the target.
  • the beat signal is incident by the original exit port of the optical circulator 2, and is output from the third port of the optical circulator 2, coupled to the photodetector 6 via the optical fiber, and converted into an electrical signal.
  • the relative displacement amount ⁇ d of the target moving object can be calculated by measuring the offset ⁇ b0 of the initial phase, as shown in FIG. 2 .
  • the optical circulator 2 uses a 3-port circulator. In other embodiments, the optical circulator 2 can also use a 4-port circulator.
  • the fiber collimator 3 can use one of an existing G-lens fiber collimator, a spherical lens (C-lens) fiber collimator, or an aspheric fiber collimator.
  • the cooperative mirror [5] providing the signal light may be a partial mirror or a total reflection mirror, and may be a dielectric mirror or a metal mirror, and the cooperative mirror needs to be attached to the surface of the moving object to be tested and It moves together.
  • Both the partial mirror 4 and the cooperative mirror 5 need to be strictly perpendicular to the direction of the laser light exiting the fiber collimator 3 to ensure that the reflected reference light and signal light can be coupled back to the original fiber path through the fiber collimator 3 at maximum power.
  • a two-way form of frequency modulation continuous wave laser interference fiber displacement sensor is provided.
  • a single mode frequency modulated continuous wave laser 1 is connected to two optical fiber displacement sensing systems. It is said that the single-mode frequency-modulated continuous wave laser 1 is connected to the two-way fiber displacement sensing system through the 1 ⁇ 2 fiber coupler 7, and the setting mode and working principle of each of the two fiber displacement sensing systems and the single-channel fiber displacement The sensing system is the same.
  • the laser power output from the single-mode frequency-modulated continuous wave laser 1 is used by the 1 ⁇ 2 fiber coupler 7 to average the two-way frequency-modulated continuous-wave laser interference fiber displacement sensor.
  • the two-way fiber displacement sensing system independently measures the displacement of the target object. The displacement measurement of the motion of two independent moving objects can be realized at the same time, and the measurement of the displacement of the same object in the two-dimensional space can also be realized.
  • the fiber-optic displacement sensing system is similar in extension, except that the 1x2 fiber coupler 7 is replaced with a 1x3 or 1xN fiber coupler 7, each of which is identical to a single-channel frequency modulated continuous wave laser fiber displacement sensor.

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  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Engineering & Computer Science (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • Radar, Positioning & Navigation (AREA)
  • Remote Sensing (AREA)
  • Electromagnetism (AREA)
  • Length Measuring Devices By Optical Means (AREA)
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Abstract

一种调频连续波激光干涉光纤位移传感器,包括单模调频连续波激光器(1)和至少一路光纤位移传感系统;光纤位移传感系统包括光学环行器(2)、光纤准直器(3)、部分反射镜(4)、合作反射镜(5)和光电探测器(6);单模调频连续波激光器(1)通过单模光纤或光纤耦合器与光学环行器(2)的入射端口相连;光学环行器(2)的相邻出射端口通过单模光纤与光纤准直器(3)相连,其第三端口与光电探测器(6)相连,光纤准直器(3)后设置部分反射镜(4),部分反射镜(4)后设置合作反射镜(5),合作反射镜(5)附着于待测目标物体表面并与其一起移动。调频连续波激光干涉光纤位移检测方法。

Description

一种调频连续波激光干涉光纤位移传感器及其位移检测方法 技术领域
本发明涉及位移传感技术领域,具体涉及一种调频连续波激光干涉光纤位移传感器。
背景技术
位移传感在科研、工业以及军事领域都是极为重要的计量测试技术。光学位移传感技术由于精度高、非接触、不受电磁干扰的特点,尤其受到重视。其中,光纤位移传感技术更是具有体积小、重量轻、结构紧凑、形式灵活的优点。目前,已经有多种光纤位移传感技术见诸报道,主要包括两类,一种是强度调制型光纤位移传感器,一种是激光干涉型光纤位移传感器。强度调制型光纤位移传感器在探测方法和信号处理上更为简单,但是存在精度低、稳定性差、响应非线性、测量范围小的缺点。采用传统光学零拍干涉技术的激光干涉式光纤位移传感器可以实现非常高的测量精度,不过其测量精度依赖于激光波长的稳定性,并且由于干涉信号为静态信号存在条纹计数困难的问题,很难获得大动态范围的高精度位移传感。
发明内容
本申请提供一种调频连续波激光干涉光纤位移传感器及其位移检测方法,解决现有技术中存在的问题。
本发明的技术方案如下:
一种调频连续波激光干涉光纤位移传感器,包括单模调频连续波激光器和与所述单模调频连续波激光器连接的至少一路光纤位移传感系统;所述的光纤位移传感系统包括光学环行器、光纤准直器、部分反射镜、合作反射镜和光电探测器;所述单模调频连续波激光器通过单模光纤或者光纤耦合器与光学环行器的入射端口相连,光学环行器的相邻出射端口通过单模光纤与光纤准直器相连,光学环行器的第三端口与光电探测器相连,光纤准直器后设置部分反射镜,部分反射镜后设置合作反射镜,合作反射镜附着于待测目标物体表面并与其一起移动。
进一步的,所述单模调频连续波激光器通过单模光纤或者光纤耦合器与光学环行器的入射端口熔接或者通过法兰连接。
进一步的,所述部分反射镜通过胶黏或者机械固定的方式附于光纤准直器的出射端面。
进一步的,在所述光纤准直器的出射镜面镀有部分反射部分透射光学薄膜材料,构成所述的部分反射镜。
进一步的,所述的光纤准直器选用格林透镜(G-lens)光纤准直器、球面透镜(C-lens)光纤准直器或非球面光纤准直器。
进一步的,所述合作反射镜选用部分反射镜或全反射镜。
进一步的,所述合作反射镜为全反射镜时,选用介质反射镜或金属反射镜。
根据上面所说的光纤位移传感器,其位移检测方法如下:单模调频连续波激光器发射的调频连续波由单模光纤或者光纤耦合器耦合至光学环行器的入射端口,由光学环行器的相邻出射端口输出,然后通过光纤准直器耦合输出,一部分出射光被部分反射镜反射,另一部分出射光由部分反射镜透射并照射在随待测目标物体移动的合作反射镜的镜面上,合作反射镜将光线反射使其返回部分反射镜并与部分反射镜的反射光叠加干涉,形成拍频信号,拍频信号由光纤准直器耦合回单模光纤,并入射至光学环行器,由光学环行器的第三端口出射,并通过单模光纤耦合至光电探测器转换为电信号,通过对该电信号的处理分析,可以得到目标物体的位移信息。
本发明的有益效果如下:
1.本发明极大的降低了测试激光在光路中的损耗,提高激光能量的利用效率,消除了反馈光对光源的影响,显著提高了调频连续波激光干涉信号的信噪比,可以在数厘米以上的大量程范围内,获得<10nm的测量精度,实现大动态范围的精密光纤位移传感测量。
2.本发明构成了全光纤式的调频连续波激光干涉光纤位移传感光路,其结构紧凑,性能稳定。
附图说明
图1是本发明实施例1的结构示意图。
图2是位移传感测量过程中,拍频信号初相位偏移量与待测目标位移之间的关系图。
图3是本发明实施例2的结构示意图。
图中,1-单模调频连续波激光器,2-光学环行器,3-光纤准直器,4-部分反射镜,5-合作反射镜,6-光电探测器,7-光纤耦合器。
具体实施方式
为了使本发明的目的、技术方案和优点更加清楚,下面将结合附图对本发明作进一步地详细描述,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做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。
本发明调频连续波激光干涉光纤位移传感器包括单模调频连续波激光器1和与所述单模调频连续波激光器连接的至少一路光纤位移传感系统;光纤位移传感系统包括光学环行器2、光纤准直器3、部分反射镜4、合作反射镜5和光电探测器6;所述单模调频连续波激光器1通过单模光纤或者光纤耦合器7与光学环行器2的入射端口相连,光学环行器2的相邻出射端口通过单模光纤与光纤准直器3相连,光学环行器2的第三端口与光电探测器6相连,光纤准直器3后设置部分反射镜4,部分反射镜4后设置合作反射镜5,合作反射镜5与待测目标物体一起移动。
本发明调频连续波激光干涉光纤位移传感器的基本原理是:利用调频连续波激光干涉技术,可以自然产生一个动态拍频信号,利用该动态信号初相位与物体相对位移量之间的线性关系,可以实现对物体相对位移量的测量。这种光纤位移传感器具备测量精度高、可辨别位移方向、测量动态范围大等优点,因此基于调频连续波激光干涉的光纤位移传感器测量精度、动态范围均高于传统激光干涉式光纤位移传感器。
下面介绍本发明的几种实施例:
实施例1:
如图1所示,实施例1提供一种单路形制的调频连续波激光干涉光纤位移传感器,即单模调频连续波激光器仅连接一路光纤位移传感系统;具体的说:单模调频连续波激光器1通过单模光纤与光学环行器2的一个端口连接,在本实施例中,它们通过熔接的方式连接;但在在其他实施例中,它们也可以使用法兰连接。
光学环行器2的相邻出射端口通过单模光纤与光纤准直器3的尾纤连接,光学环行器2的第三端口通过单模光纤与光电探测器6的尾纤连接。
部分反射镜4设置在光纤准直器后端,本实施例中,部分反射镜4作为独立器件置于光纤准直器3之后;但在在其他实施例中,部分反射镜4也可通过胶黏或者机械固定的方式附于光纤准直器3的出射端面外,或者通过在光纤准直器3出射端面镀设部分反射部分透射光学薄膜材料,实现部分反射镜4的功能。
通过电流调制的方式,使用单模调频连续波激光器1发射频率线性调制的调频连续波激光,该激光通过光纤耦合至光学环行器的一个输入端口,从光学环行器2的相邻出射端口输出,输出后的光经由单模光纤入射至光纤准直器3,由光纤准直器3经过部分反射镜4,部分光被反射,作为参考光,部分光透射后,照射至附于待测移动物体表面的合作反射镜5并被反射,作为信号光,信号光原路返回,在部分反射镜4反射面上参考光叠加干涉,形成拍频信号,拍频信号由光纤准直器3耦合回光纤光路,并由光学环行器2的原出射端口入射,由光学环行器2的第三端口出射,被光电探测器6接收并转换为电信号。
假定参考光平均光强为I 1,信号光平均光强为I 2,则拍频信号光强
Figure PCTCN2018122245-appb-000001
其中,I 0=I 1+I 2,V为拍频信号的对比度,并且
Figure PCTCN2018122245-appb-000002
Δν为光学频率调制宽度,ν m为调制信号的频率,c为光速,t为时间,λ 0为光波在真空中的波长,ν b为拍频信号频率,φ b0为拍频信号初相位。OPD为参考光与信号光的光程差,显然
Figure PCTCN2018122245-appb-000003
Figure PCTCN2018122245-appb-000004
对于该调频连续波激光干涉位移传感器,光程差OPD=2nd,显然,拍频信号的初相位可以写为
Figure PCTCN2018122245-appb-000005
n为空气折射率(n≈1),d为部分反射镜4反射面与附于目标移动物体表面的合作反射镜[5]反射面之间的间距。当目标移动物体带动部分反射镜5移动δd的距离时,初相位的φ b0偏移量为
Figure PCTCN2018122245-appb-000006
Figure PCTCN2018122245-appb-000007
拍频信号由光学环行器2原出射端口入射,并从光学环行器2的第三端口输出,经由光纤耦合至光电探测器6,转化为电信号。通过测量初相位的偏移量 δφ b0即可计算出目标移动物体的相对位移量δd,如图2所示。
需要说明的是,在本实施例中,光学环行器2使用的是3端口环行器,在其他实施例中,光学环行器2也可以使用4端口环行器。光纤准直器3可以使用现有的格林透镜(G-lens)光纤准直器、球面透镜(C-lens)光纤准直器或者非球面光纤准直器的一种。提供信号光的合作反射镜[5]可以是部分反射镜,也可以是全反射镜,可以是介质反射镜,也可以是金属反射镜,该合作反射镜需要附于被测移动物体表面并随其一起移动。部分反射镜4和合作反射镜5均需要与光纤准直器3出射的激光方向严格垂直,以保证反射的参考光和信号光能够以最大功率通过光纤准直器3耦合回原光纤光路。
实施例2:
与实施例1不同的是,本实施例中,提供一种两路形式的调频连续波激光干涉光纤位移传感器,参见图3,单模调频连续波激光器1连接两路光纤位移传感系统,具体的说,单模调频连续波激光器1通过1×2光纤耦合器7分别连接两路光纤位移传感系统,这两路中每一路光纤位移传感系统的设置方式和工作原理与单路光纤位移传感系统相同。
单模调频连续波激光器1输出的激光功率由1×2光纤耦合器7平均非配给两路调频连续波激光干涉光纤位移传感器使用,两路光纤位移传感系统分别独立对目标物体的位移进行测量,可以同时实现对两个独立运动物体运动的位移测量,也可以实现对同一物体在二维空间中运动位移量的测量。
本领域人员可以在上述两种形制的基础之上,可以进一步拓展位移传感系统的数目,比如设置三路以及多路位移传感系统,三路以及多路位移传感系统的拓展方式与两路光纤位移传感系统的扩展方式相似,只是将1×2光纤耦合器7用1×3或1×N光纤耦合器7替换,各路以与单路调频连续波激光光纤位移传感器相同。
以上应用了具体个例对本发明进行阐述,只是用于帮助理解本发明,并不用以限制本发明。对于本发明所属技术领域的技术人员,依据本发明的思想,还可以做出若干简单推演、变形或替换。

Claims (8)

  1. 一种调频连续波激光干涉光纤位移传感器,其特征在于,包括单模调频连续波激光器和与所述单模调频连续波激光器连接的至少一路光纤位移传感系统;所述的光纤位移传感系统包括光学环行器、光纤准直器、部分反射镜、合作反射镜和光电探测器;所述单模调频连续波激光器通过单模光纤或者光纤耦合器与光学环行器的入射端口相连,光学环行器的相邻出射端口通过单模光纤与光纤准直器相连,光学环行器的第三端口与光电探测器相连,光纤准直器后设置部分反射镜,部分反射镜后设置合作反射镜,合作反射镜与附着于待测目标物体表面并与其一起移动。
  2. 根据权利要求1所述的调频连续波激光干涉光纤位移传感器,其特征在于,所述单模调频连续波激光器通过单模光纤或者光纤耦合器与光学环行器的入射端口熔接或者通过法兰连接。
  3. 根据权利要求2所述的调频连续波激光干涉光纤位移传感器,其特征在于,所述部分反射镜通过胶黏或者机械固定的方式附于光纤准直器的出射端面。
  4. 根据权利要求2所述的调频连续波激光干涉光纤位移传感器,其特征在于,在所述光纤准直器的出射镜面镀有部分反射部分透射光学薄膜材料,构成所述的部分反射镜。
  5. 根据权利要求3或4所述的调频连续波激光干涉光纤位移传感器,其特征在于,所述的光纤准直器选用格林透镜(G-lens)光纤准直器、球面透镜(C-lens)光纤准直器或非球面光纤准直器。
  6. 根据权利要求5所述的调频连续波激光干涉光纤位移传感器,其特征在于,所述合作反射镜选用部分反射镜或全反射镜。
  7. 根据权利要求6所述的调频连续波激光干涉光纤位移传感器,其特征在于,所述合作反射镜为全反射镜时,选用介质反射镜或金属反射镜。
  8. 根据权利要求1所述光纤位移传感器的位移检测方法,其特征在于,单模调频连续波激光器发射的调频连续波由单模光纤或者光纤耦合器耦合至光学环行器的入射端口,由光学环行器的相邻出射端口输出,然后通过光纤准直器耦合输出,一部分出射光被部分反射镜反射,另一部分出射光由部分反射镜透射并照射在随待测目标物体移动的合作反射镜的镜面上,合作反射镜将光束反射使其返回部分反射镜并与部分反射镜的反射光叠加干涉,形成拍频信号,拍频信号由光纤准直器耦合回单模光纤,并入射至光学环行器,由光学环行器的第三端口出射,并通过单模光纤耦合至光电探测器转换为电信号,通过对该 电信号的处理分析,可以得到目标物体的位移信息。
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