CN205448974U - Little displacement measurement device of intensity demodulation type long period grating based on S type optic fibre - Google Patents

Abstract

The utility model discloses a little displacement measurement device of intensity demodulation type long period grating based on S type optic fibre, it comprises broadband light source, incident single mode fiber, S type optic fibre, long period grating, outgoing single mode fiber, optical power meter, and wherein the long period grating is carved on S type optic fibre. Through fixing this sensing structure on need measuring micro - displacement platform, move when changing when the microbit that awaits measuring, S type optic fibre is because axial stress leads to the crookedness to change, the increase that moves along with the microbit that awaits measuring of the perpendicular distance of S type optic fibre both sides promptly and reducing, fibre core and the covering energy distribution of S type optic fibre change, and the light intensity that leads to measuring device to export the harmonic peak changes, can obtain the change volume that the microbit was moved through monitoring this change. The device can avoid using complicated and dear measuring and demodulalation system, can use widely in environmental parameter measures.

Description

A kind of intensity demodulation type long-period gratings micro-displacement measuring device based on S type optical fiber

Technical field

This utility model belongs to micrometric displacement parameter measurement field, a kind of measurement apparatus that can measure micron dimension micrometric displacement.

Background technology

Such as micro Process in optical device and some commercial Application, robotics, atomic force microscope and MEMS etc. need accurate operation to control application aspect, and microdisplacement measurement is a key factor, is paid high attention to by domestic and international researcher for a long time.Common optical fiber optical micrometric displacement measurement has following structure, bragg grating, LPFG, optical taper, dislocation optical fiber.These structures are the most fairly simple, easily manufacture, but the above-mentioned structure of major part is all Wavelength demodulation type, so inevitably using complicated and expensive detection and demodulating system.The fiber grating micro-displacement sensor of nearest novel intensity demodulation type causes to be paid close attention to widely.As utilized single mode and photonic crystal fiber to constitute Mach-Zehnder interferometers, simple in construction, micro-displacement resolution, but manufacturing of this sensor needs expensive photonic crystal fiber；Utilize bowknot cone optical fiber and dislocation optical fiber to constitute Mach-Zehnder interferometers, it may have the highest micro-displacement resolution, but this structure is complicated, fragile different disconnected, and easily affected by external environment.

A kind of intensity demodulation type long-period gratings micro-displacement measuring device based on S type optical fiber disclosed in this utility model, using centre wavelength is that the wide spectrum of 1550nm is as measurement light source, heat sealing machine is utilized to form S type structure on general single mode fiber, inscribe long-period gratings thereon and form micro-displacement sensing head, by this measurement apparatus is fixed on micro-displacement platform to be measured, utilize the intensity variation characteristic with tested micrometric displacement at measurement apparatus export resonance peak, reach to measure the purpose of micrometric displacement.The utility model has the advantage of: only by inscribing long-period gratings on S type optical fiber, can be achieved with the high-precision sensing of micrometric displacement, only can be realized the measurement of micrometric displacement by the change of monitoring output intensity.Owing to being intensity demodulation type measurement apparatus, can avoid using detection and the demodulating system of complex and expensive, can be widely used in various environmental parameters is measured.

Summary of the invention

The purpose of this utility model is the optical fiber micro-displacement measuring device proposing a kind of simple in construction, certainty of measurement is high.

The technical solution adopted in the utility model is:

A kind of intensity demodulation type long-period gratings micro-displacement measuring device based on S type optical fiber, including wideband light source (1), incident single-mode fiber (2), S type optical fiber (3), long-period gratings (4), outgoing single-mode fiber (5), light power meter (6)；The outfan of wideband light source (1) is connected with one end of incident single-mode fiber (2), the other end of incident single-mode fiber (2) is connected with one end of long-period gratings (4), the other end of long-period gratings (4) is connected with one end of outgoing single-mode fiber (5), the other end of outgoing single-mode fiber (5) is connected with light power meter (6), and S type optical fiber (3) is positioned at the centre of long-period gratings (4).

Described a kind of based on S type optical fiber intensity demodulation type long-period gratings micro-displacement measuring device, it is characterised in that the operation wavelength of wideband light source (1) is 1520nm-1570nm.

Described a kind of based on S type optical fiber intensity demodulation type long-period gratings micro-displacement measuring device, it is characterized in that S type optical fiber (3) is positioned at the centre of long-period gratings (4), wherein dislocation width and the length of S type optical fiber (3) is respectively 35.478 μm and 686 μm.

Described a kind of based on S type optical fiber intensity demodulation type long-period gratings micro-displacement measuring device, is characterized in that long-period gratings (4) is engraved on S type optical fiber (3), and its cycle and length are respectively 600 μm and 24mm.

Operation principle of the present utility model is: after the light that wideband light source 1 sends is by entering long-period gratings 4 after one section of incident single-mode fiber 2, and in addition to the light of loss in covering, its remaining light is exported by outgoing single-mode fiber 5.When micrometric displacement to be measured changes, the cycle of long-period gratings 4 and the flexibility of S type optical fiber 3 all change, and are changed to main with the flexibility of S type optical fiber 3.The flexibility change of S type optical fiber 3 causes fibre core energy I in S type optical fiber_coreWith covering energy I_cladBoth distribution change, and cause fringe visibility k of measurement apparatus output spectrum to change, and its expression formula is expressed as follows:

$k=\frac{2\sqrt{I_{core}/I_{clad}}}{1+I_{core}/I_{clad}}---\left(1\right)$

I in formula_coreFor the light intensity in fibre core, I_cladFor the light intensity in covering.Formula (1) derivation is understood, works as I_coreAnd I_cladIn energy equal, i.e. I_coreWith I_cladRatio when being 1, measurement apparatus output fringe visibility is the strongest.

The beneficial effects of the utility model are: can form intensity demodulation type micro-displacement measuring device only by inscribing long-period gratings on the S type optical fiber that general single mode fiber is formed, do not depending on traditional spectrogrph, the measurement of micrometric displacement can realized just with light power meter.Additionally, described measurement apparatus has higher sensitivity, in 0-50 μ m, sensitivity is up to 0.172dB/ μm.The method can be widely used in the measurement of other similar parameters.

Accompanying drawing explanation

Fig. 1 is the structural representation of a kind of intensity demodulation type long-period gratings micro-displacement measuring device based on S type optical fiber；

Fig. 2 is the relation schematic diagram of tested micrometric displacement and resonance peak intensity.

Detailed description of the invention

Below in conjunction with accompanying drawing, this utility model is further described:

Shown in Figure 1, a kind of intensity demodulation type long-period gratings micro-displacement measuring device based on S type optical fiber, including wideband light source (1), incident single-mode fiber (2), S type optical fiber (3), long-period gratings (4), outgoing single-mode fiber (5), light power meter (6)；The outfan of wideband light source (1) is connected with one end of incident single-mode fiber (2), the other end of incident single-mode fiber (2) is connected with one end of long-period gratings (4), the other end of long-period gratings (4) is connected with one end of outgoing single-mode fiber (5), the other end of outgoing single-mode fiber (5) is connected with light power meter (6), and S type optical fiber (3) is positioned in the middle of long-period gratings (4).

Above-mentioned a kind of based on S type optical fiber intensity demodulation type long-period gratings micro-displacement measuring device, the operation wavelength of its wideband light source (1) is 1520nm-1570nm；Described S type optical fiber (3) is positioned at the centre of long-period gratings (4), and its length is respectively 35.478 μm and 686 μm；Cycle and the length of described long-period gratings (4) are respectively 600 μm and 24mm.

A kind of intensity demodulation type long-period gratings micro-displacement measuring device based on S type optical fiber, its working method is: the centre wavelength of wideband light source 1 is 1550 nanometers, when its light sent is by entering long-period gratings 4 after incident single-mode fiber 2, a part of light enters the covering of long-period gratings 4 and S type optical fiber 3, another part light is maintained in fibre core transmission, when the optical transport in fibre core and covering to outgoing single mode 5, two-beam meets and produces the resonance peak of specific wavelength.When extraneous micrometric displacement changes, the flexibility of S type optical fiber reduces along with the increase of micrometric displacement, thus causes resonance peak intensity to change, and the mechanical periodicity of long-period gratings, much smaller than the flexibility change of S type optical fiber, can be ignored.Fig. 2 is the relation schematic diagram of tested micrometric displacement and resonance peak intensity, when microdisplacement measurement scope is 0-50 μm, measures sensitivity and is up to 0.172dB/ μm.

Claims (4)

1. an intensity demodulation type long-period gratings micro-displacement measuring device based on S type optical fiber, including wideband light source (1), incident single-mode fiber (2), S type optical fiber (3), long-period gratings (4), outgoing single-mode fiber (5) light power meter (6)；The outfan of wideband light source (1) is connected with one end of incident single-mode fiber (2), the other end of incident single-mode fiber (2) is connected with one end of long-period gratings (4), the other end of long-period gratings (4) is connected with one end of outgoing single-mode fiber (5), the other end of outgoing single-mode fiber (5) is connected with light power meter (6), and S type optical fiber (3) is positioned in the middle of long-period gratings (4).

A kind of intensity demodulation type long-period gratings micro-displacement measuring device based on S type optical fiber the most according to claim 1, is characterized in that the operation wavelength of wide spectrum light source (1) is 1520nm-1570nm.

A kind of intensity demodulation type long-period gratings micro-displacement measuring device based on S type optical fiber the most according to claim 1, it is characterized in that S type optical fiber (3) is positioned at the centre of long-period gratings (4), wherein dislocation width and the length of S type optical fiber (3) is respectively 35.478 μm and 686 μm.

A kind of intensity demodulation type long-period gratings micro-displacement measuring device based on S type optical fiber the most according to claim 1, is characterized in that long-period gratings (4) is engraved on S type optical fiber (3), and its cycle and length are respectively 600 μm and 24mm.