Collimating mirror fine setting is used to improve the optical fiber grating regulating system of spectral resolution
Technical field
The present invention relates to sensory field of optic fibre, use collimating mirror fine setting to improve spectrally resolved particularly to one
The optical fiber grating regulating system of rate and method.
Background technology
Fiber grating is a kind of novel passive sensing element, has high sensitivity, and anti-electromagnetic interference capability is strong,
The plurality of advantages such as corrosion-resistant, from since sensing, has had been achieved for the development of Fast Persistence, in aviation
The safety monitoring aspect in the fields such as space flight, building structure, oil has broad application prospects.Optical fiber light
Grid demodulating system is the key component of whole sensor-based system, it is achieved in high precision, high-resolution, dynamic and quiet
State property combines, multipoint multiplexing detects and low cost is the trend that fiber grating demodulation technology develops.Optical fiber
The method of demodulation has multiple, and tuning F-P filter method is only used for measuring static strain, tunable laser
The cost of method is the highest, and non-equilibrium M-Z interferometric method is the most affected by environment, is unfavorable for engineer applied.Along with
The fast development of optical detector in recent years so that Miniature optical fiber spectrogrph is fast-developing, based on spectrum
The optical fibre interrogation technology of imaging method grows up the most therewith.Fiber Bragg grating (FBG) demodulator based on light spectrum image-forming method
Volume is little, and integration degree is high, can be used for measuring static and dynamic strain, has in numerous demodulation methods
There is outstanding advantages, be an important directions of demodulating system research, wherein, the optical system of (FBG) demodulator
The resolution of system can be directly affects, be a key of (FBG) demodulator.
The optical system structure kind of grating spectrograph is more, and current Application comparison is generally
Czerny-Turner light channel structure, i.e. using two sides concave mirror as collimating mirror and imaging lens, with
Plane reflection grating is as dispersion element.It is low that on the one hand this be because plane grating design difficulty, is copied into
This is cheap, and diffraction efficiency is high;On the other hand due to Czerny-Turner structure scalable and layout
Structural parameters are more, can avoid secondary or repeatedly diffraction, it is simple to use photoelectric array detector to receive light
Spectrum.Common Small-sized C zerny-Turner spectrogrph is broadly divided into chiasma type and 2 kinds of structures of M type.M
Type is the classical architecture of Czerny-Turner spectrogrph, and representative products is that Avantes company of Holland develops
Avaspec series small fiber spectrometer;Chiasma type is then to be developed by it, its more compact structure,
Space availability ratio is high.But, due to linear array image sensor pixel Limited Number, spectral space is differentiated
Rate is restricted.
Accordingly, it is capable to no, to realize high-resolution gration wavelength in the case of line array sensor pixel is limited accurate
Demodulation, is this area technical problem urgently to be resolved hurrily.
Summary of the invention
It is an object of the invention to provide a kind of optical fiber light using collimating mirror fine setting to improve spectral resolution
Grid demodulating system, described demodulating system includes pumping source, wavelength division multiplexer, bragg grating, light
Door screen, slit, collimating mirror, spectro-grating, imaging lens and linear array detector, piezoelectric-actuator and voltage
Control system, wherein said pumping source, wavelength division multiplexer and bragg grating are sequentially connected with, described
Wavelength division multiplexer is simultaneously connected with diaphragm, and the light that described pumping source sends is laggard by the coupling of wavelength division multiplexer
Entering bragg grating, the reflectance spectrum of described bragg grating enters fiber grating as injecting light
Demodulating system, after injection light passes through slit, passes sequentially through the reflection of collimating mirror, spectro-grating, imaging lens,
Finally converging on linear array detector, wherein said collimating mirror is along counterclockwise or the small angle that turns clockwise
Degree.
Preferably, described minute angle is 10 °-30 °.
Preferably, described collimating mirror is adjusted at a high speed by piezoelectric-actuator.
Preferably, the method for described rotation minute angle is as follows:
A) piezoelectric-actuator regulates to least significant end, and this voltage is initial adjustment voltage;
B) record least significant end spectroscopic data is initial spectrum;
C) half step distance regulation piezoelectric-actuator, calculates current light spectrum and initial spectrum, and described piezoelectricity performs
Element is position servo, is instructed by input position and controls collimating mirror rotation minute angle, to incident illumination
Locus be adjusted, finally determine light spectrum image-forming position;
D) first degree of association peak value time regulation voltage be recorded as eventually adjusting voltage;
E) between voltage, initial adjustment voltage and whole tune being divided into some grades, each grade is all carried out by demodulation every time
Measure, to obtain higher spatial resolution.
Preferably, the concrete processing procedure of described sub-step b) is as follows:
When there being 256 pixels, then can obtain 256 subsection integral values: I0, I1,
I2 ... ..I255}, when pixel scans along a direction fine motion, obtain another ordered series of numbers: I0 ', I1 ',
I2 ' ... ..I255 ' }, before this ordered series of numbers, go the former, obtain: I0 '-I0, I1 '-I1,
I2 '-I2 ... I255 '-I255, i.e. G1-G0, G2-G1, G3-G2 ... };Wherein G0 represents
The light intensity true value of the 0th position, G1 represents the light intensity value of 1 position;This ordered series of numbers is sued for peace, obtains
G1-G0, G2-G0, G3-G0 ... G255-G0}, so obtain is new after for the first time fine setting
New value after value, followed by second time fine setting, if having finely tuned n times, just obtains the interpolation of n times.
Should be appreciated that aforementioned description substantially is exemplary illustration and explanation with follow-up detailed description,
The restriction of content claimed to the present invention should not be used as.
Accompanying drawing explanation
With reference to the accompanying drawing enclosed, the more purpose of the present invention, function and advantage will be implemented by the present invention
The described below of mode is illustrated, wherein:
Fig. 1 is the fiber grating demodulation system improving line scan image sensor spectral resolution according to the present invention
The structural representation of system;
Fig. 2 shows the fiber grating solution using slit translation to improve line scan image sensor spectral resolution
The structural representation of adjusting system;
Fig. 3 shows the fiber grating solution using collimating mirror fine setting to improve detector array spectral resolution
The structural representation of adjusting system;
Fig. 4 schematically shows the fiber grating solution using fine motion grating to improve detector array spectral resolution
The structural representation of adjusting system;
Fig. 5 schematically shows the optical fiber light using imaging lens fine setting to improve detector array spectral resolution
The structural representation of grid demodulating system;
Fig. 6 schematically shows the light using linear array detector fine setting to improve detector array spectral resolution
The structural representation of fine grating demodulation system;
Fig. 7 schematically shows the knot of the optical fiber grating regulating system improving detector array spectral resolution
Structure schematic diagram;
The employing collimating mirror fine setting that Fig. 8 schematically shows according to the present invention improves line scan image sensor spectrum
The flow chart of the feedback of the optical fiber grating regulating system of resolution;
Fig. 9 (a) shows that a light intensity is one-dimensional Gaussian curve scattergram in space;
Fig. 9 (b) shows the result figure after the repetitive measurement result interpolation after scanning when not regulating slit;
Fig. 9 (c) shows the result figure after the repetitive measurement result interpolation after scanning when regulating slit.
Detailed description of the invention
Fig. 1 is the fiber grating demodulation system improving line scan image sensor spectral resolution according to the present invention
The structural representation of system;A kind of employing collimated light path fine motion that the present invention provides improves line scan image sensor
The optical fiber grating regulating system 100 of spectral resolution is as it is shown in figure 1, described optical fiber grating regulating system 100
Including pumping source (LD) 101, wavelength division multiplexer (WDM) 102, bragg grating (FBG)
103, diaphragm 104, slit 105, spectro-grating 106, collimating mirror 107, imaging lens 108 and linear array
Detector (CCD) 109.Pumping source 101, wavelength division multiplexer 102 and bragg grating 103
Being sequentially connected with, wavelength division multiplexer 102 is simultaneously connected with diaphragm 104.The light that pumping source 101 sends passes through ripple
Bragg grating 103, bragg grating 103 anti-is entered after the coupling of division multiplexer 102
Penetrate spectrum and enter optical fiber grating regulating system as injecting light.Inject light by, after slit 105, passing sequentially through
Collimating mirror 106, spectro-grating 107, the reflection of imaging lens 108, finally converge to linear array detector (CCD)
On 109.
First, by pumping source 101, wavelength division multiplexer 102, bragg grating 103 with Fig. 1 institute
Showing mode welding, wherein bragg grating 103 should have higher reflectance and narrower live width.
Wavelength division multiplexer (WDM) 102 according to the embodiment of the present invention, bragg grating (FBG)
The parameter of 103 selects to be required to same pumping wavelength, laser emitting wavelength parameter coupling, and concrete parameter is such as
Shown in table 1.
Table 1 is according to the reflectance spectrum light source parameters of the demodulating system of the present invention
If selecting core diameter in embodiment is that 10/125 μm Er-doped fiber is as gain media, pumping source LD
Tail optical fiber, wavelength division multiplexer WDM need to choose same model core diameter.Pumping source LD output wavelength 976nm,
Wavelength division multiplexer WDM operation wavelength 976/1550nm, bragg grating FBG selection range is
1530nm-1560nm, can obtain laser output within the range.If selecting core diameter in experiment is 10/125
μm Yb dosed optical fiber is as gain media, and pumping source LD tail optical fiber, wavelength division multiplexer WDM need to choose same
Template core diameter.Pumping source LD is 915nm single-mode output, wavelength division multiplexer WDM operation wavelength
915/1064nm, bragg grating FBG choose near 1064nm, can obtain within the range
Laser exports.
The reflection light of bragg grating 103 is irradiated to collimating mirror as incident illumination a through diaphragm 104
106 collimations maintaining light beam, then collimated light is irradiated on spectro-grating 107 carry out diffraction light splitting,
Afterwards through imaging lens 108, converge in linear array detector 109.
Spectro-grating 107 can be represented by formula (1)
N λ=d (sin α ± sin β) (1)
Wherein n is the order of spectrum, n=0, ± 1, ± 2....;α is angle of incidence;β is angle of reflection;θ is for glittering
Angle;D is grating constant.
N=0 is zero order spectrum, and now, β with λ is unrelated, i.e. without light splitting effect;N=± 1, ± 2 correspond to
First-order spectrum and second order spectrum, wherein first-order spectrum energy is strong, can be used for realizing light splitting.Grating resolution
Unrelated with wavelength, the spectrum after separation belongs to all arranges spectrum, and the theoretical resolution of grating is grating line number
With the product of the order of spectrum time, formula (2) can be had to represent
R=nN (2)
Being 50mm for width, groove number is the grating of 1200/mm, the resolution of its first-order spectrum
Rate is 6 × 104.
Bragg grating 103 is reflected light as inject light source, which reduce the spectrum width of incident illumination,
It is obtained in that under conditions of grating resolution determines and is more spaced finer interference fringe.Now to narrow
Seam, diaphragm, spectro-grating, collimating mirror, imaging lens and linear array detector are adjusted, and pass through input bit
Put instruction control the micro-movement of slit or control spectro-grating, collimating mirror, imaging lens and linear array detector
Micro-rotation, is adjusted the locus of incident illumination, then the light path inciding imaging lens changes,
Converge to the striped on linear array detector also occur to change accordingly, finally determine light spectrum image-forming position.
Specifically, following example it is described in detail.
Embodiment 1
Fig. 2 diagrammatically illustrates the optical fiber using slit translation to improve line scan image sensor spectral resolution
The structural representation of grating demodulation system.As in figure 2 it is shown, slit 105 is adjusted, make slit edge
Shown by arrow b moves in direction, and slit moving step length is 0.1 micron, and range of accommodation is between 0-1 centimetre.
Slit 105 is adjusted at a high speed by piezoelectric-actuator.Piezoelectric-actuator is come by voltage control system
Control, make light spectrum image-forming move in minimum pixel interval in the position of line scan image sensor
Dynamic.So, the light path inciding imaging lens 108 will change, and converges to linear array detector 109
On striped also occur to change accordingly.By regulating the width of optical fiber input slit, it is possible to realize striped
Minute movement, thus reach improve measuring accuracy effect.
Embodiment 2
Fig. 3 schematically shows the optical fiber light using collimating mirror fine setting to improve detector array spectral resolution
The structural representation of grid demodulating system.As it is shown on figure 3, collimation mirror 106 is adjusted, make collimating mirror
Rotating along shown by arrow c direction, the anglec of rotation is counterclockwise or to turn clockwise 10 °-30 °.Collimation
Mirror 106 is adjusted at a high speed by piezoelectric-actuator.Piezoelectric-actuator is controlled by voltage control system
System, makes light spectrum image-forming move in minimum pixel interval in the position of line scan image sensor
Dynamic.So, the light path inciding imaging lens 108 will change, and converges to linear array detector 109
On striped also occur to change accordingly.By regulating the anglec of rotation of collimating mirror, it is possible to realize striped
Minute movement, thus reach to improve the effect of measuring accuracy.
Embodiment 3
Fig. 4 schematically shows the fiber grating using fine motion grating to improve detector array spectral resolution
The structural representation of demodulating system.As shown in Figure 4, spectro-grating 107 is adjusted, makes light splitting light
Grid rotate along shown by arrow d direction, and the anglec of rotation is counterclockwise or to turn clockwise 10 °-30 °.Point
Light grating 107 is adjusted at a high speed by piezoelectric-actuator.Piezoelectric-actuator passes through voltage control system
Control, make light spectrum image-forming carry out in minimum pixel interval in the position of line scan image sensor
Mobile.So, the light path inciding imaging lens 108 will change, and converges to linear array detector 109
On striped also occur to change accordingly.By regulating the anglec of rotation of spectro-grating, it is possible to realize striped
Minute movement, thus reach improve measuring accuracy effect.
Embodiment 4
Fig. 5 schematically shows the optical fiber light using imaging lens fine setting to improve detector array spectral resolution
The structural representation of grid demodulating system.As it is shown in figure 5, imaging lens 108 is adjusted, make light splitting light
Grid rotate along shown by arrow e direction, and the anglec of rotation is counterclockwise or to turn clockwise 10 °-30 °.Become
As mirror 108 is adjusted at a high speed by piezoelectric-actuator.Piezoelectric-actuator is come by voltage control system
Control, make light spectrum image-forming move in minimum pixel interval in the position of line scan image sensor
Dynamic, converge to the striped on linear array detector 109 and also occur to change accordingly.By regulation imaging lens
The anglec of rotation, it is possible to realize the minute movement of striped, thus reach to improve the effect of measuring accuracy.
Embodiment 5
Fig. 6 schematically shows the light using linear array detector fine setting to improve detector array spectral resolution
The structural representation of fine grating demodulation system.As it is shown in figure 5, linear array detector 109 is adjusted,
Spectro-grating is made to move left and right along shown by arrow f direction.Slit moving step length is 0.1 micron, regulates model
It is trapped among between 0-1 centimetre.Linear array detector 109 is adjusted at a high speed by piezoelectric-actuator.Piezoelectricity is held
Units is controlled by voltage control system, makes light spectrum image-forming exist in the position of line scan image sensor
Move in minimum pixel interval.By regulating the anglec of rotation of linear array detector, it is possible to real
The minute movement of existing striped, thus reach to improve the effect of measuring accuracy.
Embodiment 6
Fig. 7 schematically shows the knot of the optical fiber grating regulating system improving detector array spectral resolution
Structure schematic diagram.As it is shown in fig. 7, to slit, diaphragm, spectro-grating, collimating mirror, imaging lens and linear array
At least two in detector is finely adjusted, described slit, diaphragm, spectro-grating, collimating mirror, imaging
Mirror and linear array detector are adjusted at a high speed by piezoelectric-actuator.Piezoelectric-actuator passes through Control of Voltage
System controls, and makes light spectrum image-forming in the position of line scan image sensor in minimum pixel interval
Move.By regulation slit, diaphragm, spectro-grating, collimating mirror, imaging lens and linear array detector
The anglec of rotation, thus reach improve measuring accuracy effect.
Fig. 8 schematically shows the optical fiber improving line scan image sensor spectral resolution according to the present invention
The flow chart of the feedback of grating demodulation system.Concrete control method is as follows:
First, step 801, piezoelectric-actuator regulates to least significant end, and this voltage is initial adjustment voltage;
Step 802, record least significant end spectroscopic data is initial spectrum;
Step 803, half step distance regulation piezoelectric element, piezoelectric element is position servo, passes through input position
Instruction, regulates slit, spectro-grating, collimating mirror, imaging lens or linear array detector respectively, calculates current
Spectrum and initial spectrum.When regulation Gaussian image displacement on CCD arrives a pixel wide,
I.e. complete single pass, each measurement data of single pass interpolation respectively, formed one the most smooth
Curve.Its processing procedure is such, and the output of pixel is the subsection integral to light intensity curve, when having
During 256 pixels, then can obtain 256 subsection integral values: I0, I1, I2 ... ..I255},
When pixel scans along a direction fine motion, obtain another ordered series of numbers: I0 ', I1 ', I2 ' ... ..I255 ' },
Before this ordered series of numbers, go the former, obtain: I0 '-I0, I1 '-I1, I2 '-I2 ... I255 '-I255, }, i.e.
{G1-G0,G2-G1,G3-G2,......}.Wherein G0 represents that (attention is for the light intensity true value of the 0th position
0 position, rather than the light majorant for integral in pixel dimension), G1 represents the light intensity value of 1 position.To this number
Row are sued for peace, obtain G1-G0, G2-G0, G3-G0 ... G255-G0}, so obtain is the
Once the new value after the new value after fine setting, followed by second time fine setting, if having finely tuned n times, just obtains
The interpolation of n times.
Step 804, regulation voltage during degree of association peak value is recorded as adjusting voltage eventually first;
Step 805, is divided into some grades by initial adjustment voltage and whole tune between voltage, comes according to each grade
Determine displacement or the anglec of rotation of spectro-grating, collimating mirror, imaging lens or linear array detector of slit.
Step 806, returns step 803, and each grade is all measured by demodulation every time, higher to obtain
Spatial resolution.
Fig. 9 (a)-9 (c) shows that the present invention regulates slit, spectro-grating, collimating mirror, imaging lens or linear array
Detector improves the principle of spectral space resolution.Fig. 9 (a) shows that light intensity is that one-dimensional Gauss is bent in space
Line scattergram.One light intensity is that the light beam that is distributed of one-dimensional Gaussian curve is irradiated to a CCD sensing in space
On device, each pixel close-packed arrays of CCD, each pixel is equivalent to perpendicular lattice, such as Fig. 9 (a) institute
Showing, the output of pixel is really the integration to the light intensity total amount fallen on a pixel.Due to discretization mistake
Greatly, cause image resolution ratio relatively low, for improving the sampling number of curve, by regulation slit, light splitting
Grating, collimating mirror, imaging lens or linear array detector, change Gaussian curve position on ccd sensor
Put, be equivalent to mobile ccd sensor and the diverse location of curve is acquired.Slit, spectro-grating,
The fine setting of collimating mirror, imaging lens or linear array detector, is equivalent to the fine position to sensor, thus
Obtain finer and smoother the portraying of curve.Fig. 9 (b) is not for regulate slit, spectro-grating, collimating mirror, one-tenth
As the result figure after the repetitive measurement result interpolation after scanning when mirror or linear array detector.Fig. 9 (c) is regulation
When slit, spectro-grating, collimating mirror, imaging lens or linear array detector, the repetitive measurement result after scanning is inserted
Result figure after value.From Fig. 9 (b) and 9 (c), regulate slit, spectro-grating, collimating mirror, imaging
Mirror or linear array detector, when regulation Gaussian image displacement on CCD arrives a pixel wide,
I.e. complete single pass, each measurement data of single pass interpolation respectively, formed one the most smooth
Curve.
In conjunction with explanation and the practice of the present invention disclosed here, other embodiments of the present invention are for ability
Field technique personnel are easy to expect and understand.Illustrate and embodiment be to be considered only as exemplary,
True scope and the purport of the present invention are all defined in the claims.