Distributed Michelson optical fibre white light interference sensing device

Abstract

The invention provides a distributed Michelson optical fibre white light interference sensing device, comprising a broadband light source, a light source isolation device, an enquirer device, an optical fibre circulator, a lead-in / lead-out optical fibre, an optical fibre sensor array and a photoelectric detector. The light rays emitted from the light source enter the enquirer device and are then divided into two beams of which one is used as reference light and the other is used as sensing light; both the reference light and sensing light enter the optical fibre circulator, enter the optical fibre sensor array through the lead-in / lead-out optical fibre along the same transmission path, return the same way after being reflected by the sensor array and enter the photoelectric detector through the optical fibre circulator. By introducing the optical fibre circulator, the invention improves the multiplexing ability of the sensing system, improves the light source utilization efficiency and has good stability as sensing signals and reference signals share the same optical path in the sensor array.

Description

technical field

[0001] The invention relates to the technical field of optical fiber sensing, in particular to a distributed Michelson optical fiber white light interference sensing system. Background technique

[0002] An interferometer that uses broad-spectrum light as a light source and optical fiber as a transmission medium is called a fiber optic white light interferometer. A traditional fiber optic white light interferometer generally includes a sensing arm and an adjustable reference arm, and the signal transmitted along the sensing arm and reference arm is detected by a photodetector. If the optical path difference between the sensing arm and the reference arm is less than the coherence length of the light source, the two signals interfere. The characteristic of white light interference fringes is that there is a main maximum value, called the central fringe, which corresponds to the absolute equalization of the optical path of the reference beam and the measuring b...

Examples

specific Embodiment approach 1

[0041] see figure 1 , distributed Michelson optical fiber white light interference sensing device, including broadband light source 10, optical fiber isolator 20, optical fiber Michelson interrogator 30, optical fiber circulator 40, import / export optical fiber 50, optical fiber sensor array 60 and photodetector 70. The fiber Michelson interrogator 30 includes a 2×2 fiber directional coupler 301 , a fixed mirror 302 , a gradient index lens 303 and a movable scanning mirror 305 . One output port 301c of the fiber coupler 301 is connected to the fixed mirror 302 to form a fixed arm; the other output port 301d of the fiber coupler 301 is connected to the gradient index lens 303 . The scanning mirror 305 is mounted on a linear displacement stage, perpendicular to the optical axis of the gradient index lens 303 , and forms an adjustable matching distance 304 between the gradient index lens 303 and the scanning mirror 305 . The fiber optic sensor array 60 consists of several fiber o...

specific Embodiment approach 2

[0045] although figure 1 The device can improve the utilization rate of the light source and the multiplexing capability of the system, but there is still a loss of about 3 dB at the fiber coupler 301 . This is because when the signal reflected by the mirrors 302 and 305 passes through the fiber coupler 301, only half of the power enters the fiber optic sensor array 60 through the fiber optic circulator 40 along the 301b port of the coupler 301, while the other half of the light is transmitted through the port 301a. The isolator 20 is lost and does not contribute to the sensing system.

[0046] In order to further improve the effective utilization of the light source output power of the device, another embodiment of the distributed Michelson optical fiber white light interference sensing device is as figure 2 As shown, it includes broadband light source 10, optical fiber Michelson interrogator 30, optical fiber circulator 40 and 40', optical fiber circulator 80, import / expor...

specific Embodiment approach 3

[0049] In order to further improve the stability of the system, figure 2 The two three-port fiber optic circulators 40' and 80 in the shown arrangement can be replaced by a four-port fiber optic circulator. Another specific embodiment of the distributed Michelson optical fiber white light interference sensing device is as image 3 As shown, it includes a wide-spectrum light source 10, an optical fiber Michelson interrogator 30, a three-port optical fiber circulator 40, a four-port optical fiber circulator 90, import / export optical fibers 50 and 50', optical fiber sensor arrays 60 and 60', and a photodetector 70 and 70'.

[0050] image 3 The sensing principle of the shown device is related to the figure 2 The sensing principle of the shown devices is basically the same. The difference is that figure 2 The two three-port fiber optic circulators 40' and 80 of the shown arrangement are replaced by one four-port fiber optic circulator 90. One port 90a of the circulator 90...

technical field

[0001] The invention relates to the technical field of optical fiber sensing, in particular to a distributed Michelson optical fiber white light interference sensing system. Background technique

[0002] An interferometer that uses broad-spectrum light as a light source and optical fiber as a transmission medium is called a fiber optic white light interferometer. A traditional fiber optic white light interferometer generally includes a sensing arm and an adjustable reference arm, and the signal transmitted along the sensing arm and reference arm is detected by a photodetector. If the optical path difference between the sensing arm and the reference arm is less than the coherence length of the light source, the two signals interfere. The characteristic of white light interference fringes is that there is a main maximum value, called the central fringe, which corresponds to the absolute equalization of the optical path of the reference beam and the measuring b...

Examples

specific Embodiment approach 1

[0041] see figure 1 , distributed Michelson optical fiber white light interference sensing device, including broadband light source 10, optical fiber isolator 20, optical fiber Michelson interrogator 30, optical fiber circulator 40, import / export optical fiber 50, optical fiber sensor array 60 and photodetector 70. The fiber Michelson interrogator 30 includes a 2×2 fiber directional coupler 301 , a fixed mirror 302 , a gradient index lens 303 and a movable scanning mirror 305 . One output port 301c of the fiber coupler 301 is connected to the fixed mirror 302 to form a fixed arm; the other output port 301d of the fiber coupler 301 is connected to the gradient index lens 303 . The scanning mirror 305 is mounted on a linear displacement stage, perpendicular to the optical axis of the gradient index lens 303 , and forms an adjustable matching distance 304 between the gradient index lens 303 and the scanning mirror 305 . The fiber optic sensor array 60 consists of several fiber o...

specific Embodiment approach 2

[0045] although figure 1 The device can improve the utilization rate of the light source and the multiplexing capability of the system, but there is still a loss of about 3 dB at the fiber coupler 301 . This is because when the signal reflected by the mirrors 302 and 305 passes through the fiber coupler 301, only half of the power enters the fiber optic sensor array 60 through the fiber optic circulator 40 along the 301b port of the coupler 301, while the other half of the light is transmitted through the port 301a. The isolator 20 is lost and does not contribute to the sensing system.

[0046] In order to further improve the effective utilization of the light source output power of the device, another embodiment of the distributed Michelson optical fiber white light interference sensing device is as figure 2 As shown, it includes broadband light source 10, optical fiber Michelson interrogator 30, optical fiber circulator 40 and 40', optical fiber circulator 80, import / expor...

specific Embodiment approach 3

[0049] In order to further improve the stability of the system, figure 2 The two three-port fiber optic circulators 40' and 80 in the shown arrangement can be replaced by a four-port fiber optic circulator. Another specific embodiment of the distributed Michelson optical fiber white light interference sensing device is as image 3 As shown, it includes a wide-spectrum light source 10, an optical fiber Michelson interrogator 30, a three-port optical fiber circulator 40, a four-port optical fiber circulator 90, import / export optical fibers 50 and 50', optical fiber sensor arrays 60 and 60', and a photodetector 70 and 70'.

[0050] image 3 The sensing principle of the shown device is related to the figure 2 The sensing principle of the shown devices is basically the same. The difference is that figure 2 The two three-port fiber optic circulators 40' and 80 of the shown arrangement are replaced by one four-port fiber optic circulator 90. One port 90a of the circulator 90...

Images