CN100554870C - Utilize the step height on-line measuring system of fiber grating and wavelength-division multiplex technique - Google Patents
Utilize the step height on-line measuring system of fiber grating and wavelength-division multiplex technique Download PDFInfo
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- CN100554870C CN100554870C CNB2007101224048A CN200710122404A CN100554870C CN 100554870 C CN100554870 C CN 100554870C CN B2007101224048 A CNB2007101224048 A CN B2007101224048A CN 200710122404 A CN200710122404 A CN 200710122404A CN 100554870 C CN100554870 C CN 100554870C
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Abstract
The invention discloses a kind of step height on-line measuring system that utilizes fiber grating and wavelength-division multiplex technique.Utilize fiber grating reflection bragg wavelength characteristic and wavelength-division multiplex technique to constitute the Optical Fiber Composite interferometer, this interferometer contains the optical fiber Michelson interferometer that two catoptron independence light paths almost overlap.An interferometer is used for measuring; Another interferometer is used to stablize, and through the influence of feedback control circuit compensate for ambient interference to measuring system, thereby makes system be applicable to on-line measurement.The light that the super-radiance light emitting diode of spectrum width 40nm sends is entered system by the light that three different fiber grating reflections of bragg wavelength comprise three wavelength, and a wavelength acts on stablizes in the interferometer systems stabilisation; Two wavelength act in the stellar interferometer in addition, produce synthesis wave to interfere, realize measuring.Regulating action can get the synthetic wavelength of different sizes in the size of two wavelength of stellar interferometer, realizes the differing heights step height measurement.
Description
Technical field
The present invention relates to a kind of step height on-line measuring system that utilizes fiber grating and wavelength-division multiplex technique, particularly relate to a kind of bench height measuring system that is applicable to on-line measurement, belong to field of optical measuring technologies.
Background technology
[1] D.P.Hand, T.A.Carolan, J.S.Barton, and J.D.C.Jones, optics letter (Optics Letters),, the 18th volume, the 16th phase, 1361-1363 page or leaf in 1993.The principle of work of prior art document [1] as shown in Figure 1, light that semiconductor laser sends through 50: 50 coupling mechanisms of faraday isolator and optical fiber after, arrive measuring head, measuring head is a Feisuo interferometer, part light is reflected conduct with reference to light by fiber end face, after another part light focuses on through GRIN Lens, project on the measured surface, come back in the system and by measured surface reflection and to interfere with reference light, interference signal is surveyed by detector D1, and the phase decision of interference signal is in vertical height of measured surface measured point; The drive current that changes this laser instrument is to change the glow frequency of laser instrument, light with four kinds of different frequencies is measured same point, obtain four interference signals, because incident light wave frequency difference, the phase place of four interference signals are just different, regulate drive current, make the phase differential pi/2 of adjacent two interference signals, by following formula, can demodulate the optical path difference D of this point, promptly finish the measurement of single-point:
I
n(n=1,2,3,4) are the intensity of the n time interference signal, and c is the light velocity, and v is the incident light frequency.
Stepper motor drives measuring head transversal scanning measured surface again, promptly finishes the measurement to measured surface.
[2] Dejiao Lin, Xiangqian Jiang, Fang Xie, Wei Zhang, Lin Zhang and IanBennion, optics express train (Optics Express),, the 12nd volume, the 23rd phase, 5729-5734 page or leaf in 2004.The principle of work of prior art document [2] as shown in Figure 2, sending wavelength by semiconductor laser is λ
0Light be divided into two-way after through two 3dB-coupling mechanisms, the one tunnel is reflected by fiber grating, another road is reflected by reference mirror.The two-way reflected light is through meeting once more behind the 3dB-coupling mechanism and interfering, interference signal is through behind the gyroscope, reflected by another fiber grating, pass through gyroscope once more, surveyed by the PIN detector then, the signal that this detector detects is handled the length that the rear drive piezoelectric ceramic tube is regulated the reference arm of fibre optic interferometer through servo circuit, makes two interference arms stablizing interferometer be in quadrature (phase differential is a pi/2) all the time, thereby realizes stablizing the purpose of this interferometer.
The wavelength X that tunable laser is sent
mVariable light is divided into two-way after through two optical fiber 3dB-coupling mechanisms, one the tunnel through getting back in the interferometer once more by measuring mirror reflection again behind the optical fiber self-focus lens, get back in the interferometer once more by the reference mirror reflection again behind another road process optical fiber self-focus lens, meet behind the two-way light process 3dB-coupling mechanism, form interference signal, behind this interference signal process gyroscope and the fiber grating, surveyed, promptly measure the displacement of measuring mirror through phase analysis again by the PIN detector.
The problem and shortage that above-mentioned two prior aries exist is:
1, measuring system is disturbed sensitivity to ambient vibration and temperature drift etc., is not suitable for on-line measurement.
2, the bench height of Ce Lianging is subjected to the restriction of incident light wave length λ, and measurable bench height only is the hundreds of nanometer less than λ/2, can't measure to the bench height of hundreds of micron tens.
Purpose of the present invention is exactly to propose a kind of step height on-line measuring system that utilizes fiber grating and wavelength-division multiplex technique at the problem and shortage of prior art existence.
Summary of the invention
The objective of the invention is to be achieved through the following technical solutions.
A kind of step height on-line measuring system that utilizes fiber grating and wavelength-division multiplex technique, this system is made up of superradiation light-emitting two pipe SLD, fiber grating FBG, gyroscope, 3dB-coupling mechanism, optical fiber self-focus lens GRIN, piezoelectric ceramics PZT, measurement catoptron, reference mirror, detector PD, signal circuit processing, phase measurement, feedback control circuit, A/D transition card, signal generator, computing machine, output result.Centre wavelength is that the light that the super-radiance light emitting diode of 1550nm spectrum width 40nm sends is λ through three different fiber grating reflection wavelengths of bragg wavelength
1, λ
2And λ
3Light enter measuring system.Utilize the characteristic of fiber grating reflection bragg wavelength, interfering the end of arms to write a fiber grating that parameter is identical respectively at two of the optical fiber Michelson interferometer that is used to measure, is that catoptron constitutes another again and is used for stable optical fiber Michelson interferometer with these two fiber gratings; Measure Michelson interferometer and stable Michelson interferometer independently catoptron is arranged separately, the gage beam of two interferometers and the light path of reference arm almost overlap, to be wrapped on the piezoelectric ceramic tube PZT1 as the optical fiber of reference arm, feedback control circuit drive pressure electroceramics PZT1, regulate the length of reference arm, compensation since temperature drift and ambient vibration to the influence of stable fiber Michelson interferometer, make two of the stable fiber Michelson interferometer to interfere arm to be in quadrature (two phase differential pi/2s of interfering arm) all the time, the stable fiber Michelson interferometer is just stable like this, because the light path of measuring optical fiber Michelson interferometer almost overlaps with the light path of stable fiber Michelson interferometer, the measuring optical fiber Michelson interferometer is also stable.The frequency response range of feedback control circuit is 0～5kHz, that is to say that feedback control circuit can the correction-compensation frequency be the influence of the undesired signal of 0～5kHz to measuring system, makes that measuring system is applicable to on-line measurement.Because the characteristic of the characteristic of fiber grating reflection bragg wavelength and chirped fiber grating reflection special spectrum, making wavelength is λ
1Light action in the stable fiber Michelson interferometer, finish steady operation, other two wavelength X
2, λ
3Light action in the measuring optical fiber Michelson interferometer, form synthesis wave to interfere, finish surveying work.Synthetic wavelength is
Be far longer than λ
2, λ
3, native system can be measured bench height.Regulate the initial position of reference mirror, the initial phase difference that makes two arms of measuring optical fiber Michelson interferometer is zero, because the variation of bench height when causing Δ d variation, the initial phase difference of two arms will become when the light path of gage beam
So the variable quantity of initial phase difference is directly proportional with the variable quantity of bench height, realize measurement to bench height by the variable quantity of measuring initial phase difference.
Beneficial effect of the present invention mainly contains two:
1, this measuring system is applicable to on-line measurement.System utilizes the characteristic of fiber grating reflection bragg wavelength to constitute stable fiber Michelson interferometer and the measuring optical fiber Michelson interferometer that is combined with each other, make two of the stable fiber Michelson interferometer to interfere arm to be in quadrature all the time by feedback control circuit, make the stable fiber Michelson interferometer stable, thereby make the measuring optical fiber Michelson interferometer also stable, make measuring system be applicable to on-line measurement.
2, this measuring system can be measured bench height.Method with synthesis wave to interfere enlarges interferometry range, synthetic wavelength
Be far longer than optical wavelength λ
2And λ
3, the maximum height of the step that can measure is λ
s/ 2, can be by regulating optical wavelength λ
2And λ
3Size obtain the synthetic wavelengths of different sizes, realize step height measurement to differing heights.
Description of drawings
Fig. 1 is the fundamental diagram of prior art document [1];
Fig. 2 is the fundamental diagram of prior art document [2];
Fig. 3 is a fundamental diagram of the present invention.
Mark among the figure: SLD-super-radiance light emitting diode, FBG-fiber grating, CFBG7-chirped fiber grating, PZT1-piezoelectric ceramic tube, the stacked piezoelectric ceramics of PZT2-, GRIN-fiber collimating lenses, PD-detector.
Embodiment
Below in conjunction with accompanying drawing 3 and embodiment the present invention is further described.
As shown in Figure 3, the bragg wavelength of fiber grating FBG1, FBG2 and FBG3 reflection is respectively λ
1, λ
2, λ
3, the bragg wavelength of FBG4, FBG5 and FBG6 reflection is λ
1, the reflectance spectrum of chirped fiber grating CFBG7 comprises λ
2, λ
3, but do not comprise λ
1Fiber grating FBG4 and FBG5 write on two ends of interfering arm of measuring optical fiber Michelson interferometer respectively, like this, with fiber grating FBG4 and FBG5 is that catoptron constitutes the stable fiber Michelson interferometer again, and the light path of stable fiber Michelson interferometer and measuring optical fiber Michelson interferometer almost overlaps.Centre wavelength is that the light that the super-radiance light emitting diode of 1550nm spectrum width 40nm sends arrives fiber grating FBG1, FBG2 and FBG3 through gyroscope 1 back, by fiber grating FBG1, FBG2 and FBG3 reflected back λ
1, λ
2, λ
3The light of three wavelength, this light is divided into two-way through behind gyroscope 1, gyroscope 2 and the 3dB-coupling mechanism, and when two-way light arrived fiber grating FBG4 and FBG5, wavelength was λ
1Light be reflected, wavelength is λ
2, λ
3Transmittance; The two-way wavelength X that is reflected
1Light pass through the 3dB-coupling mechanism once more, meet at 3dB-coupling mechanism place and interfere, one road interference signal is through gyroscope 2, gyroscope 3 and chirped fiber grating CFBG4, survey by detector PD1, another road interference signal is reflected by fiber grating FBG6 through gyroscope 4 backs, pass through gyroscope 4 once more, survey by detector PD2.The signal that detector PD1 and PD2 detect is handled through feedback control circuit, act on the piezoelectric ceramic tube PZT1 as feedback signal, the reference arm of fibre optic interferometer is wrapped on the PZT1, feedback signal drives the length that PZT1 regulates optical fiber, regulate the light path of reference arm with this, make two of the stable fiber Michelson interferometer to interfere arm to be in quadrature (interfering the phase differential of arm to be always pi/2 for two) all the time, this just compensates and has revised the influence of interference such as temperature drift and ambient vibration to the stable fiber Michelson interferometer, has realized stablizing the stable fiber Michelson interferometer.Because the light path of measuring optical fiber Michelson interferometer almost overlaps with the light path of stable fiber Michelson interferometer, so the measuring optical fiber Michelson interferometer is also stable.The operating frequency range of this feedback control circuit is 0～5kHz, that is to say that this feedback control circuit can revise and compensate the undesired signal of 0～5kHz, make the measuring optical fiber Michelson interferometer accurately carry out surveying work, make measuring system be applicable to on-line measurement.Seeing through fiber grating FBG4 and FBG5 wavelength is λ
2And λ
3Two-way light respectively through two fiber collimating lenses GRIN, be collimated into parallel beam, gone back to system by reference mirror and measurement mirror reflects respectively, pass through fiber grating FBG4 and FBG5 once more, and the generation synthesis wave to interfere that meets at 3dB-coupling mechanism place, synthetic wavelength is
One road synthesis wave to interfere signal by chirped fiber grating CFBG7 reflection, passes through gyroscope 3 backs by guiding system through gyroscope 2 and 3 once more, behind another road interference signal process gyroscope 4 and the fiber grating FBG6, is surveyed by detector PD3.When bench height changes, the phase place of synthesis wave to interfere signal will change.When bench height changes delta d, the phase changing capacity of synthesis wave to interfere signal is:
λ in the formula
sBe synthetic wavelength.By equation (1) as long as demodulate the phase changing capacity of interference signal as can be known
Through data processing, can measure the changes delta d of bench height.For this reason, system adds periodic sawtooth voltage to the piezoelectric ceramics PZT2 in the reference path, periodically the light path of linear regulation reference path.Regulate the amplitude and the reference path light path of sawtooth voltage, make initial periodic sawtooth voltage and interference signal with the cycle same-phase.When bench height changes delta d, the phase place of sawtooth voltage is just different with the phase place of interference signal, measures the phase differential between the two, through after the data processing, promptly obtains tested displacement variation delta d value.
Above-mentioned instantiation has been described in realization in order to demonstrate the invention.But other variations of the present invention and modification it will be apparent to those skilled in the art that, in the essence of the disclosed content of the present invention and any modification/variation in the cardinal rule scope or imitate conversion all to belong to claim protection domain of the present invention.
Claims (3)
1, a kind of step height on-line measuring system that utilizes fiber grating and wavelength-division multiplex technique, it is characterized in that: this system comprises and is combined with each other and two optical fiber Michelson interferometers that light path almost overlaps, is respectively applied for and measures loop and feedback control loop; This system is made up of super-radiance light emitting diode (SLD), gyroscope, fiber grating (FBG), chirped fiber grating (CFBG), 3dB-coupling mechanism, detector (PD), optical fiber self-focus lens (GRIN), measurement catoptron, reference mirror, piezoelectric ceramic tube (PZT1), stacked piezoelectric ceramics (PZT2), feedback control circuit, signal circuit processing module, phase measurement module, A/D transition card, signal generator, computing machine and output result; Two identical fiber gratings of parameter lay respectively at two ends of interfering arm of an optical fiber Michelson interferometer that is used to measure, with these two fiber gratings is that catoptron has constituted another again and is used for the optical fiber Michelson interferometer of stably measured system, and these two optical fiber Michelson interferometers have separately independently catoptron and light path almost overlap; One of them optical fiber as the reference arm that with the fiber grating is the optical fiber Michelson interferometer that constitutes of catoptron is wrapped on the piezoelectric ceramic tube, drive piezoelectric ceramic tube by feedback control circuit, regulate the length of the reference arm of interferometer, make with the fiber grating is that two of the optical fiber Michelson interferometer of catoptron interfere arms to be in quadrature, promptly the phase differential of two interference arms is a pi/2, like this, just having compensated ambient vibration and temperature drift, to give fiber grating be the influence that the optical fiber Michelson interferometer of catoptron brings, and reached the purpose of stablizing this interferometer; Because the light path of two interferometers almost overlaps,, thereby make this system be applicable to on-line measurement so another optical fiber Michelson interferometer that is used to measure is also stable; The light that super-radiance light emitting diode sends is reflected by the fiber grating of three different bragg wavelengths, the light that comprises three kinds of wavelength after being reflected enters measuring system, utilize the characteristic of fiber grating reflection bragg wavelength and the characteristic of chirped fiber grating reflection special spectrum, the light action that makes one of them wavelength is in the stable fiber Michelson interferometer, be used for the stably measured system, the light action of other two wavelength forms synthesis wave to interfere in the measuring optical fiber Michelson interferometer, realize measuring; It is zero that the position of adjusting reference mirror makes the initial phase difference of two arms of measuring optical fiber Michelson interferometer, by stacked piezoelectric ceramics the light path of its reference arm is modulated, the phase differential of two arms that makes stellar interferometer is by 2 π that are increased to of zero line; Because the variation of bench height when causing the variation of Δ d, the variable quantity of the initial phase difference of two arms is when the light path of gage beam
λ
sBe synthetic wavelength, the variable quantity of initial phase difference is directly proportional with the variable quantity of bench height, realizes measurement to bench height by the variable quantity of measuring initial phase difference.
2, according to the said a kind of step height on-line measuring system that utilizes fiber grating and wavelength-division multiplex technique of claim 1, it is characterized in that: interfere the end of arm to write a fiber grating that parameter is identical respectively for two at an optical fiber Michelson interferometer, utilize two optical fiber Michelson interferometers that the characteristic formation is combined with each other and light path almost overlaps of fiber grating reflection bragg wavelength, an optical fiber Michelson interferometer is finished steady operation, another optical fiber Michelson interferometer is finished surveying work, thereby makes measuring system be applicable to on-line measurement.
3, according to the said a kind of step height on-line measuring system that utilizes fiber grating and wavelength-division multiplex technique of claim 1, it is characterized in that: the light that super-radiance light emitting diode sends is reflected by the fiber grating of three different bragg wavelengths, the light that comprises three kinds of wavelength after being reflected enters measuring system, and three kinds of wavelength are respectively λ
1, λ
2And λ
3, utilize the characteristic of fiber grating reflection bragg wavelength and the characteristic of chirped fiber grating reflection special spectrum again, make wavelength X
1Act in the stable fiber Michelson interferometer, finish steady operation, make measuring system be applicable to on-line measurement; Wavelength X
2And λ
3Act in the measuring optical fiber Michelson interferometer, form synthesis wave to interfere, realize measurement bench height; Synthetic wavelength
The maximal value of measurable bench height is λ
s/ 2; By regulating the parameter of fiber grating, regulate λ
2And λ
3Size, obtain the synthetic wavelengths of different sizes, realize measurement, and by computing machine output result to the differing heights step.
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| CN101738215B (en) * | 2008-11-14 | 2014-01-29 | 北京航空航天大学 | Multi-reflection-based dual-beam pulse interferometry |
| US9158032B2 (en) * | 2010-02-18 | 2015-10-13 | US Seismic Systems, Inc. | Optical detection systems and methods of using the same |
| CN102494615B (en) * | 2011-11-15 | 2013-09-04 | 清华大学 | Step distance measuring device based on femtosecond optical-frequency comb and measuring method thereof |
| CN104301101B (en) * | 2014-10-22 | 2017-08-01 | 上海交通大学 | A kind of quantum key distribution system phase compensating method |
| CN105333816B (en) * | 2015-11-05 | 2018-04-10 | 北京交通大学 | A kind of super online interferometer measuration system of lateral resolution surface three dimension based on the spectral dispersion whole audience |
| CN109387161A (en) * | 2018-09-06 | 2019-02-26 | 中国科学院西安光学精密机械研究所 | A kind of auto-collimation system |
| CN110967048B (en) * | 2019-12-28 | 2021-11-05 | 桂林电子科技大学 | Orthogonal inclined three-core fiber grating parallel integrated Mach-Zehnder interferometer |
| CN111006753B (en) * | 2019-12-30 | 2021-12-03 | 珠海任驰光电科技有限公司 | Phase feedback controlled optical fiber interference ultralow frequency vibration measuring device and method |
| CN112082581B (en) * | 2020-06-05 | 2022-12-13 | 哈尔滨工业大学 | Quasi-distributed physical quantity measuring method, device and system based on distributed feedback laser array |
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