CN107764197B - A kind of optical system axial direction parameter measuring apparatus and method - Google Patents
A kind of optical system axial direction parameter measuring apparatus and method Download PDFInfo
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- CN107764197B CN107764197B CN201710959724.2A CN201710959724A CN107764197B CN 107764197 B CN107764197 B CN 107764197B CN 201710959724 A CN201710959724 A CN 201710959724A CN 107764197 B CN107764197 B CN 107764197B
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
- G01B11/00—Measuring arrangements characterised by the use of optical techniques
- G01B11/14—Measuring arrangements characterised by the use of optical techniques for measuring distance or clearance between spaced objects or spaced apertures
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
- G01B11/00—Measuring arrangements characterised by the use of optical techniques
- G01B11/02—Measuring arrangements characterised by the use of optical techniques for measuring length, width or thickness
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01M—TESTING STATIC OR DYNAMIC BALANCE OF MACHINES OR STRUCTURES; TESTING OF STRUCTURES OR APPARATUS, NOT OTHERWISE PROVIDED FOR
- G01M11/00—Testing of optical apparatus; Testing structures by optical methods not otherwise provided for
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Abstract
The invention discloses a kind of optical system axial direction parameter measuring apparatus and methods, the device includes: low-coherence measuring unit, Gao Xianggan scale unit, scanning element, measuring range multiplication unit and signal processing unit, and low-coherence measuring unit is for generating low coherence interference wave；The relevant scale unit of height is for generating high coherent interference wave；Low coherence reference light and high coherent measurement light are scanned unit, and scanning element is used to provide same optical time delay line for low coherence interference wave and high coherent interference wave；Measuring range multiplication unit is used to acquire the low coherence interference wave of low-coherence measuring unit generation and expands the range of measuring range；Signal processing unit is used to be analyzed and processed the collected low coherence interference wave of measuring range multiplication unit using high coherent interference wave as reference data, obtain the axial distance between each dielectric interface of optical system.Optical system axial direction parameter measuring apparatus provided by the invention and method have the characteristics that measurement range is big, signal-to-noise ratio is high, measure quick and precisely.
Description
Technical field
The present invention relates to field of optical measurements, more particularly to a kind of optical system axial direction parameter measuring apparatus and method.
Background technique
The measurement of corresponding optical system axial direction parameter, generally uses following two system in the prior art: a kind of system note
It is loaded in " High stability multiplexed fibre interferometer and its application on
Absolute displacement measurement and on-line surface metrology ", Optics
Express, Vol.12, Issue 23,2004, P.5729-5734. (Optics Express (optics is express), 2004, the
Volume 12, the 23rd phase, P.5729-5734) in, this system includes the Michelson's interferometer that two optical paths are almost overlapped.Semiconductor
It is λ that laser, which issues wavelength,0Light detected after a Michelson's interferometer by detector, the letter that this detector detects
Number by servo circuit processing rear-guard move piezoelectric ceramic tube adjust fibre optic interferometer reference arm length, realization stablize the interference
The purpose of instrument, the wavelength X that tunable laser issuesmVariable light is visited after another Michelson's interferometer by detector
It surveys, is the displacement for measuring measurement mirror using phase analysis.Using measurement mirror and reference mirror as the composition of reflecting mirror, it is used for
Complete measurement work.One fibre optic interferometer (sensor fibre interferometer) Ml is placed in tested field and incudes measured position by another system
It moves, with the value of another and the concatenated fibre optic interferometer of sensor fibre interferometer Ml (demodulation fibre optic interferometer) M2 demodulation displacement,
To realize long-range measurement to displacement.Based on wavelength-division multiplex technique, the wavelength of Bragg condition is met using fiber grating reflection
Light, make demodulate fibre optic interferometer M2 work at the same time in low coherence interference and high coherent interference state, believed using low coherence interference
Number determine displacement amplitude, limit measuring range by optical wavelength, and realize absolute measurement, utilize high coherent interference signal
The value of displacement is measured, and inhibits influence of the environmental disturbances to demodulation fibre optic interferometer M2 using feedback control, realizes that high-precision is surveyed
Amount.
But two above system has what measuring range was limited, range is by incident light wave in the first system
The limitation that wavelength enters, and not can be carried out absolute measurement；Range is by one-dimensional travel limit in second of system.
Summary of the invention
The object of the present invention is to provide a kind of optical system axial direction parameter measuring apparatus and method, big with measurement range,
Signal-to-noise ratio is high, measurement quick and precisely the characteristics of.
To achieve the above object, the present invention provides following schemes:
A kind of optical system axial direction parameter measuring apparatus, described device include:
Low-coherence measuring unit, the low-coherence measuring unit is for generating low coherence interference wave；The low-coherence measuring
Unit includes low-coherence light source, and the low-coherence light source issues low-coherence measuring light and Low coherence reference light, and the Low coherence is dry
Relating to wave is that light and the Low coherence of the low-coherence measuring light after being tested optical system reflection are formed with reference to the interference of light
Light wave；
The relevant scale unit of height, the high relevant scale unit is for generating high coherent interference wave；The high relevant scale
Unit includes high-coherence light source, and the high-coherence light source issues high coherent measurement light and high coherent reference light, the high relevant survey
Amount light and high coherent reference light interfere, and form high coherent interference wave；
Scanning element, the Low coherence reference light and the high coherent measurement light pass through the scanning element, described to sweep
Unit is retouched for providing same optical time delay line for the low coherence interference wave and the high coherent interference wave；
Measuring range multiplication unit, the measuring range multiplication unit are used to acquire the low phase that the low-coherence measuring unit generates
Dry interference wave and the range for expanding measuring range；
Signal processing unit, the signal processing unit are used for using the high coherent interference wave as reference data, to range
The collected low coherence interference wave of multiplication units is analyzed and processed, and obtains the axis between each dielectric interface of optical system
To distance；
The low-coherence measuring unit is connected with the measuring range multiplication unit, the signal processing unit respectively with it is described
Measuring range multiplication unit, the high relevant scale unit are connected.
Optionally, the low-coherence measuring unit further includes the first coupler, the first Polarization Controller, the first ring of light shape
Device, first collimator, the second Polarization Controller, the second optical circulator, wavelength division multiplexer, the second collimator；
The low-coherence measuring light is via successively incident after the first Polarization Controller, the first optical circulator, first collimator
Onto each dielectric interface of tested optical system, through each dielectric interface reflection after successively by first optical circulator,
First optical fiber splitter successively reaches the measuring range multiplication unit；The low-coherence measuring light passes through first optical fiber
The multichannel low-coherence measuring light obtained after splitter；
The Low coherence reference light is via the second Polarization Controller, the second optical circulator, wavelength division multiplexer, the second collimation
The scanning mirror of device, the scanning element impinges perpendicularly on the reflecting mirror of the scanning element, the reflecting mirror through the scanning element
It is returned after reflection and reaches second optical circulator, reach the range through second optical circulator, the second optical fiber splitter
Multiplication units；The multichannel Low coherence reference light that the Low coherence reference light obtains after second optical fiber splitter is adjacent
The light path of Low coherence reference light in optical path is at arithmetic progression；
The multichannel low-coherence measuring light that the low-coherence measuring light obtains after first optical fiber splitter with it is described
The multichannel low-coherence measuring light that Low coherence reference light obtains after first optical fiber splitter is in the measuring range multiplication unit
It interferes, obtains the low coherence interference wave.
Optionally, the measuring range multiplication unit includes multiple couplers and each one-to-one detector of coupler
Right, the low-coherence measuring light and the Low coherence reference light occur to do at the coupler of the measuring range multiplication unit
It relates to, obtains the low coherence interference wave；The detector is visited to the low coherence interference wave that the coupler exports
It surveys, the low coherence interference wave includes Low coherence reflection interference wave and Low coherence transmission interference wave.
Optionally, to including two detectors, two detectors are respectively used to the Low coherence detector
Reflection interference wave and the Low coherence transmission interference wave are detected.
Optionally, the high relevant scale unit includes high-coherence light source, third coupler, the 4th coupler, the 4th coupling
The optical fiber of reflectance coating is plated in clutch, third optical circulator, the 4th optical circulator and end face；
The light that the high-coherence light source issues is divided into high coherent reference light and high relevant survey after the third coupler
Light is measured, the high coherent reference light is via the third optical circulator, optical fiber, the third optical circulator of end face plating reflectance coating
After reach the 4th coupler, the high coherent measurement light via the 4th optical circulator, wavelength division multiplexer, the second collimator,
The scanning mirror of the scanning element, the reflecting mirror for impinging perpendicularly on the scanning element, after the reflection of the reflecting mirror of scanning element
Backtracking reaches the 4th optical circulator, reaches the 4th coupler after the 4th optical circulator；
The high coherent reference light and high coherent measurement light for being incident on the 4th coupler interfere, and obtain high phase
Dry interference wave, the high coherent interference wave include high coherent reflection interference wave and high relevant transmission interference wave.
Optionally, the high relevant scale unit further includes two detectors, and two detectors are respectively used to institute
The high coherent reflection interference wave and the high relevant transmission interference wave for stating the output of the 4th coupler are detected.
Optionally, between each optical device be all made of optical fiber or optical fibre device is connected.
The present invention also provides a kind of optical system axial direction measurement method of parameters, the method is applied to provided by the invention
Optical system axial direction parameter measuring apparatus, which comprises
It is closed the general supply of optical system axial direction parameter measuring apparatus, lights high-coherence light source, low-coherence light source；
It is moved forward and backward tested optical system, when the interference peaks of tested first dielectric interface of optical system appear in range
When on first group of detector in multiplier unit, fixed tested optical system；
Each group detector receives the low coherence interference signal at tested each interface of optical system in measuring range multiplication unit；
Signal processing unit extracts the maximum point of the low coherence interference signal using differential zero passage method, obtains tested light
Each interface location information of system, and the interference wave figure shown according to signal processing unit are produced with the relevant scale unit of height
Raw high coherent interference wave is with reference to the distance between tested each interface of optical system of calculating, and the interference wave figure includes low
Coherent interference wave figure and high coherent interference wave figure.
Optionally, the interference wave figure shown according to signal processing unit, the height generated with high relevant scale unit
Coherent interference wave is to specifically include with reference to the distance between tested each interface of optical system of calculating:
When the corresponding low coherence interference signal of two neighboring dielectric interface is on the same detector, formula is utilizedCalculate the axial distance of two neighboring dielectric interface, wherein d be two neighboring dielectric interface it is axial away from
From；N includes high phase between the maximum value for the corresponding low coherence interference signal of dielectric interface two neighboring in interference wave figure
The number in dry interference signal period, λ are the wavelength that high-coherence light source issues light；
When the corresponding low coherence interference signal of two neighboring dielectric interface is not on the same detector, formula is utilizedCalculate the axial distance of two neighboring dielectric interface, wherein d is adjacent
The axial distance of two dielectric interfaces；nmFor the corresponding low coherence interference signal of dielectric interface previous in interference wave figure
Include the high number for interferenceing the signal period between maximum value and high coherent interference signal initial value；nnAfter in interference wave figure
The maximum value of the corresponding low coherence interference signal of one dielectric interface is interferenceed between signal initial value with high comprising high relevant dry
Relate to the number of signal period；Lm、LnLow coherence reference light corresponding to respectively previous dielectric interface and latter dielectric interface
The light path on road；λ is the wavelength that high-coherence light source issues light.
The specific embodiment provided according to the present invention, the invention discloses following technical effects: measurement provided by the invention
The device and method of optical system axial direction parameter is provided with low-coherence measuring unit, Gao Xianggan scale unit, scanning element, amount
Journey multiplication units and signal processing unit, the low-coherence measuring unit is for generating low coherence interference wave, the high relevant mark
For ruler unit for generating high coherent interference wave, the Low coherence reference light and the high coherent measurement light are single by the scanning
Member makes the low coherence interference wave and the high coherent interference wave provide same optical time delay line, by the way that the range times is arranged
Increase the measurement range that unit increases device, signal processing unit, the signal processing unit is used for the high coherent interference
Wave is reference data, and the low coherence interference wave collected to measuring range multiplication unit is analyzed and processed, and obtains optical system
Axial distance between each dielectric interface, in addition, the detector used in device provided by the invention mentions for differential detector
The high signal-to-noise ratio of measuring signal, can be realized and accurately measure signal.
Detailed description of the invention
It in order to more clearly explain the embodiment of the invention or the technical proposal in the existing technology, below will be to institute in embodiment
Attached drawing to be used is needed to be briefly described, it should be apparent that, the accompanying drawings in the following description is only some implementations of the invention
Example, for those of ordinary skill in the art, without any creative labor, can also be according to these attached drawings
Obtain other attached drawings.
Fig. 1 is the schematic diagram of the measuring device of optical system of embodiment of the present invention axial direction parameter；
Fig. 2 is the high coherent interference waveform diagram that the relevant scale unit of height of the embodiment of the present invention generates；
Fig. 3 is the low coherence interference waveform diagram that low-coherence measuring of embodiment of the present invention unit generates；
Fig. 4 is that the embodiment of the present invention is tested instrumentation plan of the adjacent interface of optical system when in same probe；
Fig. 5 is that the embodiment of the present invention is tested the adjacent interface location of optical system one interface position when on different detectors
The instrumentation plan set；
Fig. 6 is that the embodiment of the present invention is tested the adjacent interface location of optical system another interface when on different detectors
The instrumentation plan of position；
Fig. 7 is the calibration maps of equal difference optical fiber optical path difference in measuring range multiplication of embodiment of the present invention unit；
Fig. 8 is the flow diagram of the measurement method of optical system of embodiment of the present invention axial direction parameter.
Specific embodiment
Following will be combined with the drawings in the embodiments of the present invention, and technical solution in the embodiment of the present invention carries out clear, complete
Site preparation description, it is clear that described embodiments are only a part of the embodiments of the present invention, instead of all the embodiments.It is based on
Embodiment in the present invention, it is obtained by those of ordinary skill in the art without making creative efforts every other
Embodiment shall fall within the protection scope of the present invention.
The object of the present invention is to provide a kind of optical system axial direction parameter measuring apparatus and method, big with measurement range,
Signal-to-noise ratio is high, measurement quick and precisely the characteristics of.
In order to make the foregoing objectives, features and advantages of the present invention clearer and more comprehensible, with reference to the accompanying drawing and specific real
Applying mode, the present invention is described in further detail.
Fig. 1 is the schematic diagram of the measuring device of optical system of embodiment of the present invention axial direction parameter, as shown in Figure 1, of the invention
The optical system axial direction parameter measuring apparatus of offer includes:
Low-coherence measuring unit 1, the low-coherence measuring unit 1 is for generating low coherence interference wave；The Low coherence is surveyed
Measuring unit 1 includes low-coherence light source 101, and the low-coherence light source 101 issues low-coherence measuring light and Low coherence reference light, described
Low coherence interference wave is light and the Low coherence reference light of the low-coherence measuring light after being tested optical system 106 and reflecting
Interfere the light wave formed；The light that low-coherence light source issues is the wider width of spectrum, and the very short light of coherence length is similar to compound
Coloured light is not single colored light；
The relevant scale unit 2 of height, the high relevant scale unit 2 is for generating high coherent interference wave；The high relevant mark
Ruler unit 2 includes high-coherence light source 201, and the high-coherence light source 201 issues high coherent measurement light and high coherent reference light, described
High coherent measurement light and high coherent reference light interfere, and form high coherent interference wave；The light that high-coherence light source issues is spectrum
Narrower width, the very long single colored light of coherence length.
Scanning element 3, the Low coherence reference light and the high coherent measurement light pass through the scanning element 3, described
Scanning element 3 is used to provide same optical time delay line for the low coherence interference wave and the high coherent interference wave；
Measuring range multiplication unit 4, the measuring range multiplication unit 4 are used to acquire the described of the generation of low-coherence measuring unit 1
Low coherence interference wave and the range for expanding measuring range；
Signal processing unit 5, the signal processing unit 5 are used for using the high coherent interference wave as reference data, to amount
The collected low coherence interference wave of journey multiplication units 4 is analyzed and processed, and obtains the tested each medium of optical system 106 boundary
Axial distance between face；
The low-coherence measuring unit 1 is connected with the measuring range multiplication unit 4, the signal processing unit 5 respectively with
The measuring range multiplication unit 4, the high relevant scale unit 2 are connected.
The low-coherence measuring unit 1 further includes the first coupler 102, the first Polarization Controller 103, the first optical circulator
104, first collimator 105, the second Polarization Controller 107, the second optical circulator 108, wavelength division multiplexer 109, the second collimator
110；
After the low-coherence measuring light collimates 105 devices via the first Polarization Controller 103, the first optical circulator 104, first
It is successively incident on each dielectric interface of tested optical system 106, successively by described the after the reflection of each dielectric interface
One optical circulator 104, first optical fiber splitter 401, reach the measuring range multiplication unit 4；The low-coherence measuring light warp
Cross the multichannel low-coherence measuring light obtained after first optical fiber splitter 401；
The Low coherence reference light via the second Polarization Controller 107, the second optical circulator 108, wavelength division multiplexer 109,
The scanning mirror 301 of second collimator 110, the scanning element 3 impinges perpendicularly on the reflecting mirror 302 of the scanning element 3, warp
The reflecting mirror 302 of the scanning element 3 returns after reflecting and reaches second optical circulator 108, through second optical circulator
108, the second optical fiber splitter 402 reaches the measuring range multiplication unit 4；The Low coherence reference light is by second optical fiber point
The multichannel Low coherence reference light obtained after road device 402, the light path of the Low coherence reference light in adjacent optical path is at arithmetic progression；
The measuring range multiplication unit 4 includes that multiple couplers 403,406,409,412 and each coupler correspond
Detector pair, coupler 403 corresponding detector 404, detector 405, coupler 406 corresponding detector 407, detector 408,
Coupler 409 corresponds to detector 410, detector 411, coupler 412 corresponding detector 413, detector 414, the Low coherence
The multichannel low-coherence measuring light and the Low coherence reference light that measurement light obtains after first optical fiber splitter 401 pass through
The multichannel Low coherence reference light obtained after second optical fiber splitter 402 is at the coupler of the measuring range multiplication unit
It corresponds and interferes respectively, obtain the low coherence interference wave；The detector is to described in coupler output
Low coherence interference wave is detected, and the low coherence interference wave includes Low coherence reflection interference wave and Low coherence transmission interference wave.
To including two detectors, two detectors are respectively used to the Low coherence reflection interference detector
Wave and the Low coherence transmission interference wave are detected.The signal position that two detectors receive differs 180 °.
The high relevant scale unit 2 includes high-coherence light source 201, third coupler, the 4th coupler, the 4th coupling
The optical fiber of reflectance coating is plated in device, third optical circulator, the 4th optical circulator and end face；
The light that the high-coherence light source 201 issues is divided into high coherent reference light and height after the third coupler 202
Coherent measurement light, the high coherent reference light is via the third optical circulator 203, the optical fiber 204, described of end face plating reflectance coating
The 4th coupler 205 is reached after third optical circulator 203, the high coherent measurement light is via the 4th optical circulator 206, wave
Division multiplexer 109, the second collimator 110, the scanning element 3 scanning mirror 301, impinge perpendicularly on the scanning element 3
Reflecting mirror 302, backtracking reaches the 4th optical circulator 206 after the reflecting mirror 302 of scanning element 3 reflects, through described
The 4th coupler 205 is reached after 4th optical circulator 206；
The high coherent reference light and high coherent measurement light for being incident on the 4th coupler 205 interfere, and obtain
High coherent interference wave, the high coherent interference wave include high coherent reflection interference wave and high relevant transmission interference wave.
The high relevant scale unit 2 further includes two detectors 207,208, and two detectors are respectively used to institute
It is high relevant that the high coherent reflection interference wave and the high relevant transmission interference wave for stating the output of the 4th coupler 205 carry out detection
The transmitted wave and back wave of interference wave are detected.The signal position that two detectors receive differs 180 °.
Between each optical device be all made of optical fiber or optical fibre device is connected.
The present invention also provides a kind of optical system axial direction measurement method of parameters, the method is applied to provided by the invention
Optical system axial direction parameter measuring apparatus, as shown in figure 8, this method comprises:
Step 801: the general supply of closure optical system axial direction parameter measuring apparatus lights high-coherence light source, low-coherent light
Source；
Step 802: tested optical system is moved forward and backward, when the interference peaks of tested first dielectric interface of optical system go out
When on first group of detector in present range multiplier unit, fixed tested optical system；
Step 803: the Low coherence that each group detector receives at tested each interface of optical system in measuring range multiplication unit is dry
Relate to signal；
Step 804: signal processing unit extracts the maximum point of the low coherence interference signal using differential zero passage method, obtains
Each interface location information of tested optical system, and the interference wave figure shown according to signal processing unit are taken, with the relevant mark of height
The high coherent interference wave that ruler unit generates is with reference to the distance between tested each interface of optical system of calculating, the interference wave figure
Shape includes low coherence interference wave figure and high coherent interference wave figure.
Wherein, step 804 specifically includes:
When the corresponding low coherence interference signal of two neighboring dielectric interface is on the same detector, such as Fig. 4 institute
Show, utilizes formulaCalculate the axial distance of two neighboring dielectric interface, wherein d is the boundary of two neighboring medium
The axial distance in face；N be the corresponding low coherence interference signal of two neighboring dielectric interface in interference wave figure maximum value it
Between include the high coherent interference signal period number, λ be high-coherence light source issue light wavelength；
When the corresponding low coherence interference signal of two neighboring dielectric interface is not on the same detector, such as Fig. 5,6
It is shown, utilize formulaThe axial distance of two neighboring dielectric interface is calculated,
Wherein, d is the axial distance of two neighboring dielectric interface；nmFor the corresponding low phase of dielectric interface previous in interference wave figure
Include the high number for interferenceing the signal period between the maximum value of dry interference signal and high coherent interference signal initial value；nnIt is dry
The maximum value of the corresponding low coherence interference signal of latter dielectric interface in wave figure is related to interference between signal initial value with high
Number comprising the high coherent interference signal period；Lm、LnCorresponding to respectively previous dielectric interface and latter dielectric interface
The light path of Low coherence reference path；λ is the wavelength that high-coherence light source issues light.
The device and method of measurement optical system axial direction parameter provided by the invention, is provided with low-coherence measuring unit, height
Relevant scale unit, scanning element, measuring range multiplication unit and signal processing unit, the low-coherence measuring unit are low for generating
Coherent interference wave, the high relevant scale unit is for generating high coherent interference wave, the Low coherence reference light and the high phase
Dry measure light passes through the scanning element, so that the low coherence interference wave and the high coherent interference wave is provided same optics and prolongs
When line, the measurement range of device, signal processing unit, the signal processing list are increased by the way that the measuring range multiplication unit is arranged
Member is for using the high coherent interference wave as reference data, the low coherence interference wave collected to measuring range multiplication unit to be carried out
Analysis processing, obtains the axial distance between each dielectric interface of optical system, in addition, used in device provided by the invention
Detector is differential detector, improves the signal-to-noise ratio of measuring signal, can be realized and accurately measures signal.
As another embodiment of the present invention, optical system axial direction parameter measuring apparatus provided by the invention, by Low coherence
Light source, high-coherence light source, 7 couplers, 4 optical circulators, 1 wavelength division multiplexer, 2 collimators, 2 Polarization Controllers, 1
A reflecting mirror, 9 detectors, 1 one-dimensional translation stage, 1 hollow right angle scanning mirror, at 2 fiber optic splitters, signal and data
Manage unit composition.This measuring device includes that the damp moral type fibre optic interferometer of two Mach one (survey by Gao Xianggan scale unit and Low coherence
Measure unit), one of fibre optic interferometer (low-coherence measuring unit) incudes tested optical system interface location, another light
Fine interferometer (Gao Xianggan scale unit) is for demodulating distance value between adjacent two interface.Using shared scanning element, make
The low coherence interference of system and high coherent interference state are harmonious.
The light that high-coherence light source 201 issues divides after third coupler 202 and is divided into two-way light, and light is via third all the way
The 4th coupler 205, another way light are reached after optical circulator 203, the optical fiber 204 of end face plating reflectance coating, third optical circulator 203
Via the 4th optical circulator 206, wavelength division multiplexer 109, the second collimator 110, scanning mirror 301, vertically such as it is mapped to reflecting mirror
302, backtracking reaches the 4th optical circulator 206 after the reflection of reflecting mirror 302, and the 4th is reached after the 4th optical circulator 206
Coupler 205, two-way light meets at the 4th coupler 205, and interferes, and interference signal is by detector 207, detector
208 receive (180 ° of the interference signal phase phase difference that detector 207, detector 208 receive), this interference signal may be expressed as:
I1=I0(1+Mcos(K1ΔZ)) (1)
In formula, I0For the DC component of high coherent interference signal, M is the visibility of interference fringe, K1For high-coherence light source hair
The wave number of light out, Δ Z are the optical path difference of high coherent reference optical path and high coherent measurement optical path.The waveform of interference signal such as Fig. 2 institute
Show.
The light that low-coherence light source 101 issues divides after the first coupler 102 and is divided into two-way light, all the way partially via first
Each medium of tested optical system 106 point is successively incident on after vibration controller 103, the first optical circulator 104, first collimator 105
On interface, the first optical circulator 104 is reached after the reflection of each dielectric interface, through the first optical circulator 104, the first fiber optic splitter
Device 401 successively reach coupler 403, coupler 406, coupler 409, in coupler 412, another way light is controlled via the second polarization
Device 107 processed, the second optical circulator 108, wavelength division multiplexer 109, the second collimator 110, scanning mirror 301, are vertically such as mapped to reflection
Mirror 302, backtracking reaches the second optical circulator 108 after the reflection of reflecting mirror 302, through the second optical circulator 108, fiber optic splitter
Device 402 successively reach coupler 403, coupler 406, coupler 409, in coupler 412, two-way light is in coupler 403, coupling
Device 406, coupler 409 meet at coupler 412, and interfere, and interference signal is by detector 404, detector 405, detection
Device 407, detector 408, detector 410, detector 411, detector 413, (each pair of detector receives the reception of detector 414
180 ° of interference signal phase phase difference), when the optical path difference of two-way light be less than low-coherence light source coherence length when, detector receive
To be low coherence interference signal, this signal may be expressed as:
In formula, I00For the DC component of low coherence interference signal, LcFor interference length, k is that low-coherence light source issues light
Wave number, Δ z are the optical path difference of low-coherence measuring optical path and Low coherence reference path.From (2) formula it is found that the variation of Δ z can be simultaneously
Cause visibility of interference fringes and interference signal phase change.As Δ z=0, I2It will be maximized, interference waveform such as Fig. 3 institute
Show.
When two neighboring dielectric interface location conflicts signal is on the same detector, as shown in figure 4, two Jie
The axial distance of matter interface are as follows:
In formula: d- is the axial distance of two dielectric interfaces；
Include the high relevant scale unit interference signal period in the maximum value of two dielectric interface location conflicts signals of n-
Number；
λ-is the wavelength that high-coherence light source issues light.
When two neighboring dielectric interface location conflicts signal is not located on the same detector, as shown in Figure 5, Figure 6,
The axial distance of two dielectric interfaces are as follows:
In formula: d- is the axial distance of two dielectric interfaces；
nmFor the maximum value and high relevant scale unit interference signal initial value of previous dielectric interface location conflicts signal
Between the number comprising the high relevant scale unit interference signal period, as shown in Figure 5；
nnFor the maximum value and high relevant scale unit interference signal initial value of latter dielectric interface location conflicts signal
Between the number comprising the high relevant scale unit interference signal period, as shown in Figure 6；
Lm LnFor the light path of Low coherence reference path corresponding with detector respectively；
λ-is the wavelength that high-coherence light source issues light.
The calibration of equal difference optical fiber optical path difference:
Equal difference optical fiber optical path difference design value is the coherence length of high-coherence light source, the scanning of scanning mirror in measuring range multiplication unit
The length of guide rail is slightly larger than the coherence length of high-coherence light source, and measuring principle is as shown in Figure 7.
ΔLn+2-ΔLn+1=Δ Ln+1-ΔLn1=S (5)
In formula: S is the coherence length of high-coherence light source, and the sweep length of guide rail is S' > S.
So when testee is in lower column position:
ΔLn+ S < L < Δ Ln+S′ (6)
It is that corresponding (n+1)th group of optical fiber group interference fringe occurs first in the entire moving process of scanning mirror,
It continues to move to, interference fringe also occurs in corresponding n-th group optical fiber group.
If the maximum value of the two moment location conflicts signals is at a distance from the relevant scale unit interference signal initial value of height
It is S respectivelyn+1And Sn, then have:
ΔLn+1=Δ Ln+2(Sn-Sn+1) (7)
Formula (7) can be sought (n+1)th group of optical fiber group length by n-th group optical fiber group length, and first group of optical fiber group can pass through
Low coherence positions interference signal and directly obtains with the relevant scale unit interference signal of height.
The device and method of measurement optical system axial direction parameter provided by the invention, is provided with low-coherence measuring unit, height
Relevant scale unit, scanning element, measuring range multiplication unit and signal processing unit, the low-coherence measuring unit are low for generating
Coherent interference wave, the high relevant scale unit is for generating high coherent interference wave, the Low coherence reference light and the high phase
Dry measure light passes through the scanning element, so that the low coherence interference wave and the high coherent interference wave is provided same optics and prolongs
When line, the measurement range of device, signal processing unit, the signal processing list are increased by the way that the measuring range multiplication unit is arranged
Member is for using the high coherent interference wave as reference data, the low coherence interference wave collected to measuring range multiplication unit to be carried out
Analysis processing, obtains the axial distance between each dielectric interface of optical system, in addition, used in device provided by the invention
Detector is differential detector, improves the signal-to-noise ratio of measuring signal, can be realized and accurately measures signal.
Each embodiment in this specification is described in a progressive manner, the highlights of each of the examples are with other
The difference of embodiment, the same or similar parts in each embodiment may refer to each other.
Used herein a specific example illustrates the principle and implementation of the invention, and above embodiments are said
It is bright to be merely used to help understand method and its core concept of the invention；At the same time, for those skilled in the art, foundation
Thought of the invention, there will be changes in the specific implementation manner and application range.In conclusion the content of the present specification is not
It is interpreted as limitation of the present invention.
Claims (8)
1. a kind of optical system axial direction parameter measuring apparatus, which is characterized in that described device includes:
Low-coherence measuring unit, the low-coherence measuring unit is for generating low coherence interference wave；The low-coherence measuring unit
Including low-coherence light source, the low-coherence light source issues low-coherence measuring light and Low coherence reference light, the low coherence interference wave
It is the light wave that light and the Low coherence of the low-coherence measuring light after being tested optical system reflection refer to interference of light formation；
The relevant scale unit of height, the high relevant scale unit is for generating high coherent interference wave；The high relevant scale unit
Including high-coherence light source, the high-coherence light source issues high coherent measurement light and high coherent reference light, the high coherent measurement light
It is interfered with high coherent reference light, forms high coherent interference wave；
Scanning element, the Low coherence reference light and the high coherent measurement light pass through the scanning element, and the scanning is single
Member is for providing same optical time delay line for the low coherence interference wave and the high coherent interference wave；
Measuring range multiplication unit, it is dry that the measuring range multiplication unit is used to acquire the Low coherence that the low-coherence measuring unit generates
It relates to wave and expands the range of measuring range；
Signal processing unit, the signal processing unit are used for using the high coherent interference wave as reference data, to measuring range multiplication
The collected low coherence interference wave of unit is analyzed and processed, obtain between each dielectric interface of optical system it is axial away from
From；
The low-coherence measuring unit is connected with the measuring range multiplication unit, the signal processing unit respectively with the range
Multiplication units, the high relevant scale unit are connected；
Wherein, the low-coherence measuring unit further includes the first coupler, the first Polarization Controller, the first optical circulator, first
Collimator, the second Polarization Controller, the second optical circulator, wavelength division multiplexer, the second collimator；
The low-coherence measuring light via be successively incident on after the first Polarization Controller, the first optical circulator, first collimator by
On each dielectric interface of photometry system, successively by first optical circulator, described after the reflection of each dielectric interface
First optical fiber splitter successively reaches the measuring range multiplication unit；The low-coherence measuring light passes through first fiber optic splitter
The multichannel low-coherence measuring light obtained after device；
The Low coherence reference light is via the second Polarization Controller, the second optical circulator, wavelength division multiplexer, the second collimator, institute
The scanning mirror for stating scanning element impinges perpendicularly on the reflecting mirror of the scanning element, the reflecting mirror reflection through the scanning element
It returns afterwards and reaches second optical circulator, reach the measuring range multiplication through second optical circulator, the second optical fiber splitter
Unit；The multichannel Low coherence reference light that the Low coherence reference light obtains after second optical fiber splitter, adjacent optical path
In Low coherence reference light light path at arithmetic progression；
The multichannel low-coherence measuring light that the low-coherence measuring light obtains after first optical fiber splitter and the low phase
The multichannel low-coherence measuring light that dry reference light obtains after first optical fiber splitter occurs in the measuring range multiplication unit
Interference, obtains the low coherence interference wave.
2. optical system axial direction parameter measuring apparatus according to claim 1, which is characterized in that the measuring range multiplication unit
Including multiple couplers and each one-to-one detector pair of coupler, the low-coherence measuring light and the Low coherence
Reference light interferes at the coupler of the measuring range multiplication unit, obtains the low coherence interference wave；The detection
Device is detected to the low coherence interference wave that the coupler exports, and the low coherence interference wave includes Low coherence reflection
Interference wave and Low coherence transmission interference wave.
3. optical system axial direction parameter measuring apparatus according to claim 2, which is characterized in that the detector is to packet
Two detectors are included, two detectors are respectively used to the Low coherence reflection interference wave and the Low coherence transmission interference
Wave is detected.
4. optical system axial direction parameter measuring apparatus according to claim 1, which is characterized in that the high relevant scale list
Member include high-coherence light source, third coupler, the 4th coupler, the 4th coupler, third optical circulator, the 4th optical circulator and
The optical fiber of end face plating reflectance coating；
The light that the high-coherence light source issues is divided into high coherent reference light and high coherent measurement light after the third coupler,
The high coherent reference light arrives after plating the optical fiber of reflectance coating, the third optical circulator via the third optical circulator, end face
Up to the 4th coupler, the high coherent measurement light is via the 4th optical circulator, wavelength division multiplexer, the second collimator, described
The scanning mirror of scanning element, the reflecting mirror for impinging perpendicularly on the scanning element, the reflecting mirror through scanning element reflect the road Hou Yuan
It returns and reaches the 4th optical circulator, reach the 4th coupler after the 4th optical circulator；
The high coherent reference light and high coherent measurement light for being incident on the 4th coupler interfere, and obtain high relevant dry
Wave is related to, the high coherent interference wave includes high coherent reflection interference wave and high relevant transmission interference wave.
5. optical system axial direction parameter measuring apparatus according to claim 4, which is characterized in that the high relevant scale list
Member further includes two detectors, and two detectors are respectively used to the high coherent reflection exported to the 4th coupler
Interference wave and the high relevant transmission interference wave are detected.
6. optical system axial direction parameter measuring apparatus described in -5 any claims according to claim 1, which is characterized in that each
Between optical device be all made of optical fiber or optical fibre device is connected.
7. a kind of optical system axial direction measurement method of parameters, which is characterized in that the method is applied to any one of claim 1-6
Optical system axial direction parameter measuring apparatus described in claim, which comprises
It is closed the general supply of optical system axial direction parameter measuring apparatus, lights high-coherence light source, low-coherence light source；
It is moved forward and backward tested optical system, when the interference peaks of tested first dielectric interface of optical system appear in range frequency multiplication
When on first group of detector in unit, fixed tested optical system；
Each group detector receives the low coherence interference signal at tested each interface of optical system in measuring range multiplication unit；
Signal processing unit extracts the maximum point of the low coherence interference signal using differential zero passage method, obtains tested optical system
It unites each interface location information, and the interference wave figure shown according to signal processing unit, is generated with high relevant scale unit
High coherent interference wave is with reference to the distance between tested each interface of optical system of calculating, and the interference wave figure includes Low coherence
Interference wave figure and high coherent interference wave figure.
8. measurement method according to claim 7, which is characterized in that the interference wave shown according to signal processing unit
Figure, with the high coherent interference wave that high relevant scale unit generates be with reference to calculate be tested between each interface of optical system away from
From specifically including:
When the corresponding low coherence interference signal of two neighboring dielectric interface is on the same detector, formula is utilizedCalculate the axial distance of two neighboring dielectric interface, wherein d be two neighboring dielectric interface it is axial away from
From；N includes high phase between the maximum value for the corresponding low coherence interference signal of dielectric interface two neighboring in interference wave figure
The number in dry interference signal period, λ are the wavelength that high-coherence light source issues light；
When the corresponding low coherence interference signal of two neighboring dielectric interface is not on the same detector, formula is utilizedCalculate the axial distance of two neighboring dielectric interface, wherein d is adjacent
The axial distance of two dielectric interfaces；nmFor the corresponding low coherence interference signal of dielectric interface previous in interference wave figure
Include the high number for interferenceing the signal period between maximum value and high coherent interference signal initial value；nnAfter in interference wave figure
The maximum value of the corresponding low coherence interference signal of one dielectric interface is interferenceed between signal initial value with high comprising high relevant dry
Relate to the number of signal period；Lm、LnLow coherence reference light corresponding to respectively previous dielectric interface and latter dielectric interface
The light path on road；λ is the wavelength that high-coherence light source issues light.
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