A kind of full optical fibre bending sensor based on peanut shaped structure
Technical field
The utility model relates to a kind of optical fibre bending sensor, relates in particular to a kind of full optical fibre bending sensor based on peanut shaped structure, belongs to sensory field of optic fibre.
Background technology
Flexural measurement is being played the part of more and more important role from safety monitoring to Structural Engineering field, and along with the development of optical fiber sensing technology, flexural measurement technology has obtained very large breakthrough.Compared with traditional bend sensor, the advantage such as optical fibre bending sensor has that precision is high, compact conformation, corrosion-resistant, anti-electromagnetic interference (EMI).At present, optical fibre bending sensor is mainly divided into two large classes: a kind of is optical fibre bending sensor based on waveguide mutation structure, as the optical fibre bending sensor based on dislocation welding; The another kind of optical fibre bending sensor based on short period fiber grating and long period fiber grating mixed structure, as the mixed structure bend sensor based on inclined optical fiber grating and long period fiber grating.Optical fibre bending sensor based on waveguide mutation structure has that measurement range is large, signal to noise ratio (S/N ratio) advantages of higher, but structure is not firm, reusability is poor, temperature cross influence is large, measuring accuracy is low.Optical fibre bending sensor measuring accuracy based on short period fiber grating and long period fiber grating mixed structure is high, but complex process is strict to environmental requirement, is not suitable for imbedding or measuring the distortion of interior of articles.The most important thing is, above-mentioned two kinds of optical fibre bending sensors adopt Wavelength demodulation, all need expensive spectroanalysis instrument and follow-up image processing, cause cost very high, limit its practical application.
Summary of the invention
For the deficiency of prior art scheme, the purpose of this utility model is to provide a kind of full optical fibre bending sensor based on peanut shaped structure, and this bend sensor has that measurement range is large, corrosion-resistant, simple in structure, temperature-insensitive, low cost and other advantages.
The technical scheme that the utility model technical solution problem is taked is:
A kind of full optical fibre bending sensor based on peanut shaped structure, it is characterized in that, comprise wideband light source (1), circulator (2), peanut shaped construction module (3), bragg grating (4), bandpass filter (5), light power meter (6); Described wideband light source (1) is connected with circulator one port (100), peanut shaped construction module (3) is connected with bragg grating (4) with circulator two ports (101) respectively, circulator three ports (102) are connected with bandpass filter (5) one end, and bandpass filter (5) other end is connected with light power meter (6); Described bragg grating (4) serves as catoptron, with the sensing head of peanut shaped construction module (3) formation sensor; Described bandpass filter (5), by selecting filter range to utilize light power meter (6) to measure respectively core mode power and cladding mode power that sensing head reflects, realizes bending curvature and measures.
Described peanut shaped construction module (3) is to utilize commercial heat sealing machine manually to discharge to form a ball in one end of optical fiber, in like manner make another ball, the optical fiber recycling heat sealing machine of two sections of dribblings is fused into peanut shaped construction module, its length is 0.3-3cm, and two bulb diameters are 125-400 μ m.
The beneficial effects of the utility model are:
1, utilize the principle of reflection type strength modulation to measure curvature, do not need expensive spectrometer, with low cost;
2, utilize core mode power to be only subject to the impact of temperature, and cladding mode power is subject to the impact of temperature, bending simultaneously, by to cladding mode power and core mode power subtraction, just can accurately obtain relation bending and cladding mode power, thereby solve temperature cross-sensitivity.
Brief description of the drawings
Below in conjunction with accompanying drawing and embodiment, the utility model is described in further detail.
Fig. 1 is the full optical fibre bending sensor structural representation of the utility model based on peanut shaped structure.
1 is wideband light source; 2 is circulator; 3 is peanut shaped construction module; 4 is bragg grating; 5 is bandpass filter; 6 is light power meter; 100 is circulator one port; 101 is circulator two ports; 102 is circulator three ports.
Embodiment
Elaborate below in conjunction with structure of the present utility model and principle of work:
In Fig. 1, a kind of full optical fibre bending sensor based on peanut shaped structure, comprises wideband light source 1, circulator 2, peanut shaped construction module 3, bragg grating 4, bandpass filter 5, light power meter 6; Described wideband light source 1 is connected with circulator one port 100, peanut shaped construction module 3 is connected with bragg grating 4 with circulator two port ones 01 respectively, circulator three port ones 02 are connected with bandpass filter 5 one end, and bandpass filter 5 other ends are connected with light power meter 6; Described bragg grating 4 serves as catoptron, forms the sensing head of sensor with peanut shaped construction module 3; Described bandpass filter (5), by selecting filter range to utilize light power meter (6) to measure respectively core mode power and cladding mode power that sensing head reflects, realizes bending curvature and measures.
A kind of full optical fibre bending sensor principle of work based on peanut shaped structure:
The light that wideband light source 1 sends enters peanut shaped construction module 3 by circulator 2, because mode field diameter is not mated, inspire cladding mode, part light is transmitted in covering, and remaining light still transmits in fibre core, and peanut shaped construction module 3 is very short with the distance of bragg grating 4, so the decay of the luminous energy of clad section is limited, when through bragg grating 4, cladding mode is again coupled to fibre core and is carried out reverse transfer, forms first loop.When simultaneously remaining core mode process bragg grating 4, be coupled in the core mode and cladding mode of reverse transfer, again again be coupled and got back to fibre core through peanut shaped construction module 3, form second loop, so in sensing probe, light transmission forms two loops to fibre core again from fibre core to covering.Because cladding mode is bending responsive to external world, in the time that optical fiber sensor head is bending, cladding mode field distribution and Mode Coupling characteristic thereof are affected, and bending is more severe, and loss is larger, and the cladding mode power of measurement is less.The core mode of reflection and cladding mode, after circulator three port ones 02 and bandpass filter 5, are measured Output optical power by light power meter 6.Wherein bandpass filter 5 is by selecting filter range to utilize light power meter 6 to measure respectively core mode power and cladding mode power that sensing head reflects, due to cladding mode power and bending curvature linear, obtain cladding mode power and can obtain extraneous bending information.
Embodiment
The full optical fibre bending sensor of the utility model based on peanut shaped structure as shown in Figure 1, wherein wideband light source 1 wavelength coverage is 1400-1600m, the length of peanut shaped construction module 3 is 1cm, two bulb diameters are respectively 209.459 μ m, 194.260 μ m, bragg grating 4 grid region length 1cm, centre wavelength 1550nm, reflectivity is 90%.
1400-1600nm wideband light source is connected with circulator one port (100), 1cm peanut shaped construction module 3 is connected with 1cm bragg grating 4 with circulator two port ones 01 respectively, circulator three port ones 02 are connected with bandpass filter 5 one end, and bandpass filter 5 other ends are connected with light power meter 6.1400-1600nm wideband light source 1 enters peanut shaped construction module 3 by circulator 2, because mode field diameter is not mated, inspire cladding mode, part light is transmitted in covering, and remaining light still transmits in fibre core, and 1cm peanut shaped construction module 3 is very short with the distance of 1cm bragg grating 4, so the decay of the luminous energy of clad section is limited, when through 1cm bragg grating 4, cladding mode is again coupled to fibre core and is carried out reverse transfer, forms first loop.When simultaneously remaining core mode process 1cm bragg grating 4, be coupled in the core mode and cladding mode of reverse transfer, again again be coupled and got back to fibre core through 1cm peanut shaped construction module 3, form second loop, so in sensing probe, light transmission forms two loops to fibre core again from fibre core to covering.Because cladding mode is bending responsive to external world, in the time that fibre-optical probe is bending, cladding mode field distribution and Mode Coupling ability thereof are affected, and bending is more severe, and loss is larger, and the cladding mode power measuring is less.Reflected light is exported at circulator three port ones 02, and by bandpass filter 5, the core mode that sensor is reflected separates with cladding mode, obtain the cladding mode power of reflection type strength modulation, bandpass filter 5 is by connecting power meter 6, can record cladding mode performance number, due to cladding mode power and curvature linear, thereby obtain extraneous bending information.
Above embodiment is one of preferred version in all schemes of the utility model, and other simple change to the full optical fibre bending sensor based on peanut shaped structure all belongs to the scope that the utility model is protected.