CN203929019U - Optical fiber multiple spot micro-displacement sensing device based on surface plasma resonance - Google Patents

Abstract

The utility model relates to the optical fiber multiple spot micro-displacement sensing device based on surface plasma resonance.Its feature comprises a wideband light source, a polarizer, two single-mode transmission optical fiber, a single mode sensor fibre, multiple displacement probes, multiple sensitizing ranges, a spectrometer; Described sensitizing range is multiple regions that corrosion sensor fibre forms; That displacement probe is that end face is cut is flat, the single-mode fiber of plating different-thickness gold film; Air chamber is air band gap between displacement probe and sensitizing range.Light produces evanscent field through sensor fibre in sensitizing range, produces plasma resonant vibration effect on the golden film surface of displacement probe, and the length of air chamber determines the absorption peak strength of resonance wavelength; The generation resonance wavelength difference of the golden film of different-thickness, can realize multidigit shift measurement by Wavelength demodulation.The utility model proposes a kind of simple in structure, volume is little, highly sensitive, the reusable optical fiber multiple spot micro-displacement sensing device based on surface plasma resonance.

Description

Optical fiber multiple spot micro-displacement sensing device based on surface plasma resonance

Technical field

The utility model belongs to technical field of optical fiber sensing, particularly a kind of optical fiber multiple spot micro-displacement sensing device based on surface plasma resonance.

Background technology

Microdisplacement measurement technology, is widely used in precision optical machinery manufacture, high precision in control system, and geology strain monitoring, Aerospace Engineering fields etc., are the dynamically morpheme variations in real time of monitoring feature point, measuring-signal are fed back to a kind of important technology of control center.Along with the high speed development of current micro-nano process technology, the Measurement Resolution requirement of microdisplacement measurement technology, brings up to nanoscale from micron order.Main microdisplacement measurement technology comprises electric charge coupling measurement technology, measurement by capacitance technology, laser interferometry technology and fiber grating measuring technique etc. at present.

Surface plasma resonance is called for short SPR (Surface Plasmon Resonance), it is a kind of physical phenomenon of finding the sixties in last century, refer to when the P type polarization polychromatic light sending when light source passes through the interface of film metal and medium, be greater than the cirtical angle of total reflection if meet incident angle, due to the existence of surperficial evanescent wave field and metal complex index of refraction, the light part that meets characteristic wavelength is absorbed, the phenomenon that the light of its commplementary wave length is reflected.Utilize this physical phenomenon, worked out many sensing devices, and at numerous areas such as biochemistry detection, DNA molecular detect, Pharmaceutical Analysiss etc. are used widely.

Optical fiber sensing technology, is in anti-electromagnetic interference (EMI), the sensing technology of widespread use in telecommunication and sensing and distributed measurement.It is with total internal reflection (Total Internal Reflection that light transmits in optical fiber, TIR) principle is basis, at fibre core and covering interface, can there is total reflection and produce evanescent wave field in interface in incident light, the total reflection phenomenon of inside of optical fibre is combined with surface plasma resonance technology, can be used for measuring much physics, chemistry, biological variable quantity, especially, by at the special metallic film of fiber core plated surface, can measure the concentration change of many biological chemistry amounts, such as ribonucleic acid molecule, purine molecule etc.

The current microdisplacement measurement technology based on optical fiber, it is mainly the fiber grating of making different qualities on optical fiber, due to the variation of external environment, thereby the transport property that can affect grating causes the change of flashlight transmission mode in optical fiber, by the method for phase demodulating and intensity demodulation, can obtain the information of change in displacement, sensors with auxiliary electrode were volume is larger, cost of manufacture is higher, computing method complexity, measuring accuracy is not high, and can only realize the measurement of single micrometric displacement variable quantity, the device of the optical fiber multiple spot micro-displacement sensing based on surface plasma resonance the utility model proposes, have simple in structure, volume is little, highly sensitive, reusable advantage.

Utility model content

Larger in order to overcome in prior art micro-displacement sensing device volume, cost of manufacture is higher, computing method complexity, the problem that measuring accuracy is not high, the utility model proposes a kind of simple in structure, volume is little, highly sensitive, the reusable optical fiber multiple spot micro-displacement sensing device based on surface plasma resonance.

The sensing device that the utility model is taked for technical solution problem:

Step (1) is selected a wideband light source that output wavelength is 480nm to 560nm, and an operation wavelength covers the spectrometer of 480nm to 560nm, two single-mode transmission optical fiber, a polarizer, a single mode sensor fibre, multiple displacement probes.

The flashlight that step (2) wideband light source sends, through Transmission Fibers, is polarized by polarizer, obtains the incident light of linear polarization pattern, enters sensor fibre.

The making of step (3) sensor fibre, be by a common single-mode fiber under same experiment condition, in multiple regions, carry out identical corrosion treatment, obtain multiple regions of corroding to fibre core, as producing the sensitizing range of surface plasma resonance.Due to the total internal reflection principle of work of optical fiber, the incident light of linear polarization pattern can produce an evanescent wave field on the interface of fibre core and surrounding air.The propagation constant of incident light is

$k_{\mathrm{in}}=\frac{\mathrm{\ω}}{c}\sqrt{\mathrm{\ϵ}}=\frac{\mathrm{\ω}}{c}n,$

Wherein ω is the circular frequency of incident light, and c is the velocity of propagation of light in vacuum, and n is the refractive index of fiber core.

The making of step (4) displacement probe, is to put down through cutting the end face of processing at single-mode fiber, and plating thickness is nano level metallic film.Metal inside and surperficial free electron can produce informal group vibration, in the mode of oscillation of metal surface free electron are

${\mathrm{\ω}}_s=\frac{\sqrt{4\mathrm{\π}{n}_e{e}^2/m}}{\sqrt{2}},$

The propagation constant of the surface plasma-wave producing is

$k_{\mathrm{spw}}\≈\frac{\mathrm{\ω}}{c}\sqrt{\frac{{\mathrm{\ϵn}}^2}{\mathrm{\ϵ}+n^2}},$

Wherein ε is the real part of metal complex index of refraction.The evanescent wave field that incident light produces on fibre core surface can with the surface plasma-wave of metallic film, meeting under the condition that propagation constant is equal,

k _in＝k _spw，

Produce surface plasma resonance phenomenon.Owing to existing air chamber between fiber core and the metal film of displacement detecting probe surface, can cause the intensity of resonance wavelength to change according to the length of air chamber, therefore realize the microdisplacement measurement between optical fiber and displacement probe.

Step (5) is in the time making displacement probe, by the metal film at single-mode fiber end face plating different-thickness, can obtain multiple with the different displacement probe of resonance wavelength, thereby realize the measurement simultaneously multiple sensitizing ranges of sensor fibre micrometric displacement being changed, and on frequency spectrum, obtain the Strength Changes of different resonance wavelengths, realize the multiplexing of multiple spot microdisplacement measurement.

The device that the utility model is taked for technical solution problem:

It is characterized in that comprising a wideband light source, two single-mode transmission optical fiber, a polarizer, a single mode sensor fibre, multiple displacement probes, multiple sensitizing ranges, a spectrometer; Described wideband light source is connected with polarizer through Transmission Fibers; Described sensor fibre is connected with Transmission Fibers through coupling mechanism; Described sensitizing range be on multiple regions of sensor fibre by corrosion treatment, remove fibre cladding, by exposed fibre core outside make; Described displacement probe is to cut the flat single-mode fiber end face of processing through end face and plate respectively evenly and the different golden film production of thickness multiple; Described air chamber refers to the wide air band gap of tens nanometers between displacement probe and sensor fibre sensitizing range.

The beneficial effects of the utility model are:

1, the utility model utilizes wideband light source to send the flashlight of certain bandwidth, enters sensitive zones, and the wavelength-division multiplex demodulation techniques in the communication technology are applied to sensory field of optic fibre, has realized the distributed measurement of multiple spot.

2, the utility model utilizes the variation of surface plasma resonance technology measurement space micrometric displacement, by changing the length of air chamber between optical fiber sensitizing range and fiber optics displacement probe, can realize the measurement that micrometric displacement between the two changes, and be described with displacement-light intensity curve.Utilize the surface plasma resonance effect between sensitizing range, air chamber and probe end face metal film, can realize highly sensitive micro-displacement sensing.

3, the displacement probe that the utility model uses is to make in single-mode fiber end face plating nano-gold film, by changing the kind of Coating Materials, such as silver, palladium etc., can realize the displacement measurement in micron order or other length range.

4, the utility model is on same sensor fibre, to utilize same corrosion technology to make region that multiple fibre cores are exposed as sensitizing range, operate simple and easy, this sensor fibre is placed in to region to be measured, can measures micrometric displacement or the modification of surface morphology of provincial characteristics point to be measured.

5, the utility model utilizes spectrometer, and the light intensity that can realize the corresponding different wave length in multiple tested points place changes, and realizes the optical fiber multiple spot micro-displacement sensing based on surface plasma resonance.

Brief description of the drawings

Fig. 1 is the optical fiber multiple spot micro-displacement sensing apparatus structure schematic diagram based on surface plasma resonance of the present utility model.

Fig. 2 is micro-displacement sensor structural representation of the present utility model.

Embodiment

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

As shown in Figure 1, optical fiber multiple spot micro-displacement sensing device based on surface plasma resonance comprises, wideband light source 101, Transmission Fibers 102, polarizer 103, sensor fibre 104, sensitizing range 105,106,107, displacement probe 108,109,110, Transmission Fibers coupling mechanism 111, Transmission Fibers 112, spectrometer 113.The output terminal of wideband light source 101 is connected with Transmission Fibers 102, Transmission Fibers 102 is connected with sensor fibre 104 by polarizer 103, on sensor fibre 104, utilize hydrofluorite corrosion technology to process the sensitizing range 105,106,107 of multiple equal width, sensor fibre 104 is connected with Transmission Fibers 112 by coupling mechanism 111, Transmission Fibers 112 is connected with spectrometer 113.

As shown in Figure 2, micro-displacement sensor comprises, single-mode fiber 201, core region 202, displacement probe 203, displacement probe end face metallic film 204, air chamber 205.

Working method of the present utility model is: the flashlight that wideband light source 101 sends, enter Transmission Fibers 102, inclined to one side by 103 of polarizers, enter sensor fibre 104 and propagate along fibre core with the vibration mode of linear polarization, in the sensitizing range 105 of sensor fibre 104, 106, on 107, produce respectively evanescent wave field, between the golden film surface 204 of displacement probe 203 and optical fiber sensitizing range 202, produce surface plasma resonance, the absorption peak strength of resonance wavelength, length by air chamber 205 between golden film surface 204 and fibre core determines, due to displacement probe 108, 109, 110 golden film thickness is different, make to be subject to the surface plasma resonance resonance wavelength difference of evanescent wave field excitation, can detect the light intensity variation that multiple wavelength are multiple passages by spectrometer 113, sensor fibre 104 is connected with Transmission Fibers 112 by coupling mechanism 111, and Transmission Fibers 112 is connected with spectrometer 113.

The displacement probe that the utility model uses, is the end face of single-mode fiber to be cut flat, requires smooth surface smooth.The golden film preparation of displacement probe can be used multiple coating films method, uses the single-mode fiber end face that the magnetron sputtering method in vacuum coating technology is 30mm in length to plate respectively thickness for 35nm, 45nm, the golden film of 50nm in the present embodiment.

The utility model can use multiple optic analytical instrument such as monochromator, spectrometer etc. carry out signal demodulation, by detect the variation of this resonance wavelength light intensity at multiple tested points, and microdisplacement measurement that can implementation space multiple spot.

The principle of work of sensitizing range is: when incident light is propagated in optical fiber, it is the principle of utilizing attenuated total internal reflection, exist evanescent wave at fibre core and covering interface, the covering in multiple regions of optical fiber is removed and is made into multiple sensitizing ranges, the evanescent wave field that can utilize fibre core surface to exist, excites by the plasma resonance phenomenon on the golden film surface of air chamber and fibre core coupling.

The principle of work of displacement probe is: at the fiber core of tested point, between air chamber and the golden film of displacement detecting probe surface, due to the existence of evanescent wave field and golden film complex index of refraction, can between air chamber and golden membrane interface, produce surface plasma resonance phenomenon, by changing the width of this fibre core and the intermembranous air chamber of displacement detecting probe surface gold, can make the variation of this resonance wavelength absorption peak strength, thereby realize the sensing of this micrometric displacement; By the golden film at single-mode fiber plated surface different-thickness, can obtain multiple displacement probes with different resonance wavelengths, thereby realize multiple micro-displacement sensings of waiting to levy a little on same optical fiber.

The gordian technique that this device can be realized the optical fiber multiple spot micro-displacement sensing device based on surface plasma resonance is: multiple characteristic areas of same optical fiber are carried out to the corrosion treatment of the same terms, obtain multiple regions that erode to fibre core, require to remove the covering of optical fiber sensitizing range, only remaining fibre core, as the sensitizing range of excitating surface plasma resonance; Flashlight is carried out to strict polarization manipulation, ensure that broadband signal light enters sensor fibre with the form of P type polarization, produces surface plasma resonance effect by fibre core, air band gap and nano-gold film; To multiple displacement probes of sensor fibre sensitizing range, need the strict thickness of controlling end face metal film, make each displacement probe possess different resonance wavelength.

In a specific embodiment of the present utility model, the bandwidth of wideband light source 101 is 480-560nm; Transmission Fibers 102 is single-mode fiber G.652; Sensor fibre 104 is single-mode fiber G.652; Sensitizing range 105,106,107 is respectively that region to be measured on sensor fibre 104 is corroded to processing fibre core and made; Displacement probe the 108,109, the 110th, it is 35nm that the smooth end face of the single-mode fiber that is 30mm by three segment length plates respectively thickness, 45nm, the golden film production of 55nm.The incident light of the 480-560nm bandwidth that wideband light source sends, to the rear through 103 of polarizers, while propagation in sensor fibre 104, the displacement probe 108,109,110 of corresponding different golden film thicknesses, the resonance wavelength that produces surface plasma resonance at 105,106, the 107 fibre core places, sensitizing range of sensor fibre 104 is respectively 522nm, 512nm, 518nm, by changing the length of air chamber between probe 108,109,110 and sensitizing range 105,106,107, obtain respectively displacement-light intensity curve that each tested point resonance wave strong point changes about micrometric displacement.With golden film thickness 35nm, resonance wavelength is that the micro-displacement sensor of 522nm is example, when the length of air chamber is that micrometric displacement is respectively 500nm, 750nm, when 1000nm, the relative light intensity of the absorption peak obtaining is respectively 5%, 30%, 85%, make displacement probe with golden membrane material, can realize nano level micro-displacement sensing.In addition for displacement probe 109,110, the light intensity when obtaining equally micrometric displacement and being respectively 500nm, 750nm and 1000nm.Experimental data is as shown in the table.

Shown in the above and figure is only preferred implementation of the present utility model.It should be pointed out that for the person of ordinary skill of the art, not departing under the prerequisite of principle of the present utility model, can also make some modification and improvement, these also should be considered as belonging to protection domain of the present utility model.

Claims (1)

1. the optical fiber multiple spot micro-displacement sensing device based on surface plasma resonance, is characterized in that comprising a wideband light source, two single-mode transmission optical fiber, a polarizer, a single mode sensor fibre, multiple displacement probes, multiple sensitizing ranges, a spectrometer; Described wideband light source is connected with polarizer through Transmission Fibers; Described sensor fibre is connected with Transmission Fibers through coupling mechanism; Described sensitizing range be on multiple regions of sensor fibre by corrosion treatment, remove fibre cladding, by exposed fibre core outside make; Described displacement probe is to cut the flat single-mode fiber end face of processing through end face and plate respectively evenly and the different golden film production of thickness multiple; Air chamber refers to the wide air band gap of tens nanometers between displacement probe and sensor fibre sensitizing range.