CN207019624U - A kind of dual wavelength superhet interferes real-time displacement measuring system - Google Patents
A kind of dual wavelength superhet interferes real-time displacement measuring system Download PDFInfo
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Abstract
The utility model discloses a kind of dual wavelength superhet to interfere real-time displacement measuring system.System by two wavelength differences be Δ λ laser, three polarization splitting prisms, four Amici prisms, two acousto-optic modulators, four quarter-wave plates, five plane mirrors, three polarizers, a ultra-narrow bandwidth filter piece, the transimpedance photodetector of two big bandwidth, the high sensitivity photodetector of two low bandwidth, a reference mirror, a tested speculum group into.The utility model utilizes the measuring range of synthetic wavelength interference signal lifting system caused by dual wavelength, so that the measuring range of system is much larger than the range of Single wavelength interference, can be with the phase of direct measurement synthetic wavelength, realize measurement in real time, Single wavelength interference signal is adopted to obtain using ultra-narrow bandwidth filter piece simultaneously, ensures the precision of Single wavelength interferometry while measuring range is expanded.
Description
Technical field
A kind of displacement measurement system is the utility model is related to, more particularly to a kind of dual wavelength superhet interference real-time displacement
Measuring system.
Background technology
Common Single wavelength laser interferometer displacement measuring system possesses nano level displacement measurement accuracy, but due to laser
Single wavelength is usually 1 μm or so, therefore the cycle of its interference signal only has hundreds of nanometers, limits its measuring range.Displacement is surveyed
Amount system need to increase cycle count just can with accurate recording phase place change, once change in displacement is more rapid or runs into step
Change etc. larger absolute displacement, phase ambiguity just occurs.
Constructed to solve the problems, such as that the range, Tilford et al. of Single wavelength laser interference proposes earliest using dual wavelength
A kind of synthetic wavelength expands the method for measuring system range (C.R.Tilford, Appl.Opt.16,1857 (1977)).Two
Shu Bochang is respectively λ1And λ2Laser can be using synthetic wavelength as λ1λ2/(λ1-λ2) interference signal, work as λ1And λ2When relatively,
Synthetic wavelength is much larger than Single wavelength, can thus greatly expand the range of interference offset measuring system.But with measurement amount
The expansion of journey, dual wavelength interferometry be equally encountered by two it is new the problem of：1. the interferometry precision meeting based on synthetic wavelength
Decline, 2. generally require to measure Single wavelength successively and solve again when seeking synthetic wavelength phase, it is difficult to realize real-time measurement.
Decades dual wavelength interference displacement measurement afterwards achieves very big development, such as Patent No. 02112079.X patent " double wave
Long nanometer-precision real-time interferometer " adds two-way Sine Modulated and signal processor, ensure that higher measurement accuracy,
But it is extremely difficult to theoretical precision by the modulation means less stable such as temperature modulation optical maser wavelength；Dandliker et al.
The superhet interferometric method of proposition passes through (R.Dandliker, R.Thalmann, and D.Prongue, Opt.Lett.13,339
(1988)) the different frequency displacement of the two beam laser addition to different wave length can realize the real-time measurement of synthetic wavelength, but still
Do not solve the problems, such as the decline of synthetic wavelength measurement accuracy.
Prior art can not solve two problems that dual wavelength interference fringe comes simultaneously well, meet large range high precision
Real-time interferometry demand.
Utility model content
The utility model interferes real-time displacement measuring system in view of the above-mentioned problems, proposing a kind of dual wavelength superhet, melts
The advantages of having closed synthetic wavelength interference, Single wavelength interference, superhet interference, the real-time displacement for realizing large range high precision is surveyed
Amount.
The utility model is achieved through the following technical solutions.
Mainly laser, three polarization splitting prisms, four Amici prisms, two acousto-optics by two wavelength differences for Δ λ
Modulator, four quarter-wave plates, five plane mirrors, three polarizers, a ultra-narrow bandwidth filter piece, two big bandwidth
Transimpedance photodetector, the high sensitivity photodetector of two low bandwidth, a reference mirror, a tested reflection
Mirror, signal processing circuit and host computer composition；
Two lasers send the laser of two beam different wave lengths, per Shu Jiguang respectively after respective quarter-wave plate
Incide polarization splitting prism and be divided into horizontal polarization and the two-way of vertical polarization：Wherein horizontal polarization passes through acousto-optic successively all the way
Speculum back reflection is passed through in modulator and speculum back reflection, vertical polarization all the way, and two respective reflected lights of speculum enter
It is mapped to Amici prism and closes beam output, combined beam light contains the two-way output light that frequency is different and polarization direction is different；
Two-way output light incides the 3rd Amici prism and closes Shu Bingfa beams estranged：A part of light after beam splitting is inclined by first
The piece that shakes reaches the first photodetector, the reference signal as the interference of dual wavelength superhet；Another part light after beam splitting is incident
Reflection and transmission occurs to the 3rd polarization splitting prism, is divided into the two-way of vertical polarization and horizontal polarization；
The light of the vertical polarization all the way reflected through the 3rd polarization splitting prism is referenced by the 4th quarter-wave plate
The 4th quarter-wave plate is again passed by after speculum reflection to be changed into horizontal polarization light and return to the 3rd polarization splitting prism；Through
The light for the horizontal polarization all the way that three polarization splitting prisms transmit is after the 3rd quarter-wave plate is reflected by tested speculum
Again pass by the 3rd quarter-wave plate to be changed into orthogonal polarized light and return to the 3rd polarization splitting prism, tested speculum is fixed on
Measured object surface；
The two-way laser for returning to the 3rd polarization splitting prism incides the 4th light splitting after the 3rd polarization splitting prism closes beam
Prism, reflection and transmission beam splitting occurs；A part for transmission is received as double by the second polarizer by the second photodetector
The measurement signal of wavelength superhet interference；A part for reflection is after ultra-narrow bandwidth filter piece again through the 3rd polarizer by the 3rd light
Electric explorer is received, and the 4th photodetector is placed in by the 3rd photodetector；First, second photodetector and the 3rd,
Four photodetectors are connected to host computer through signal processing circuit.
First photodetector of the present utility model, the transimpedance photodetection that the second photodetector is two big bandwidth
Device, the 3rd photodetector, the high sensitivity photodetector that the 4th photodetector is two low bandwidth, sensitivity are more than
0.1V/nW。
Signal processing circuit includes self-mixing device, bandpass filter, related phase measuring apparatus, follower and differential amplification electricity
Road.Described signal processing circuit specifically include the first low-noise amplifier, the second low-noise amplifier, the first self-mixing device,
Second self-mixing device, the first bandpass filter, the second bandpass filter, the first related phase measuring apparatus, analog-to-digital conversion module, difference are put
Big device and the second related phase measuring apparatus；First photodetector is successively through the first low-noise amplifier, the first self-mixing device and first
Bandpass filter is connected to the first related phase measuring apparatus, and the second photodetector is certainly mixed through the second low-noise amplifier, second successively
Frequency device, the second bandpass filter are connected to the first related phase measuring apparatus, and the 3rd photodetector and the 4th photodetector are successively
The second related phase measuring apparatus is connected to through difference amplifier, the first related phase measuring apparatus and the second related phase measuring apparatus are through analog-to-digital conversion mould
Block is connected to host computer.
Two described lasers send the laser of different wave length, and the wavelength difference of two beam laser is Δ λ.Wavelength difference is Δ λ
Less than 5nm, more than 2nm.
The light that two described lasers are sent is the linearly polarized light of different wave length, is changed into two after quarter-wave plate
Beam circularly polarized light, it is that the two mutually perpendicular lines in beam polarization direction are inclined to distinguish beam splitting after polarization splitting prism per beam circularly polarized light
Shake light.
The modulating frequency of two described acousto-optic modulators is different.
In specific implementation, two acousto-optic modulator modulating frequency f1And f2Respectively 100MHz and 100.01MHz, both are poor
Frequency is 10kHz.
The band of first, second described photodetector is wider than the modulating frequency of acousto-optic modulator.
The centre wavelength of described ultra-narrow bandwidth filter piece is identical with less wavelength in the two-beam that two lasers are sent.
In specific implementation, light that two lasers are sent is that wavelength is 632.8nm and 635nm linearly polarized light.Ultra-narrow band
The centre wavelength of filter plate is 632.8nm, full width at half maximum 1nm.
The three, the 4th described photodetector placement locations are close to and towards identical, to realize the difference with ambient light.
Compared with prior art, the beneficial effects of the utility model are：
1st, the utility model expands the range of measuring system using synthetic wavelength, makes the range of measuring system expand as synthesizing
The half of wavelength, and the range by reasonably choosing dual wavelength measuring system is maintained at zone of reasonableness.
2nd, the utility model ensures the measurement accuracy of measuring system using Single wavelength interference signal so that measuring system can
Ensure nano level precision while measuring range is expanded.
Brief description of the drawings
Fig. 1 is system schematic of the present utility model；
In figure：Laser 1, laser 2, the first quarter-wave plate 3, the second quarter-wave plate 4, the first polarization spectro
Prism 5, the second polarization splitting prism 6, first sound-optic modulator 7, second sound-optic modulator 8, the reflection of the first speculum 9, second
Mirror 10, the 3rd speculum 11, the 4th speculum 12, the first Amici prism 13, the second Amici prism 14, the 5th speculum 15,
Three Amici prisms 16, the first polarizer 17, the first photodetector 18, the 3rd polarization splitting prism 19, the 3rd quarter-wave
Piece 20, tested speculum 21, measured object 22, the 4th quarter-wave plate 23, reference mirror 24, the second polarizer the 25, the 4th
Amici prism 26, the second photodetector 27, ultra-narrow bandwidth filter piece 28, the 3rd polarizer 29, the 3rd photodetector the 30, the 4th
Photodetector 31.
Embodiment
It is further detailed below in conjunction with specific embodiment.
The utility model is the real-time displacement measurement for realizing large range high precision, there is provided a kind of dual wavelength superhet interference
Measuring system, the system are λ including wavelength1=632.8nm laser 1, wavelength λ2=635nm laser the 2, the 1st
/ mono- wave plate 3, the second quarter-wave plate 4, the first polarization splitting prism 5, the second polarization splitting prism 6, the first acousto-optic are adjusted
Device 7 processed, second sound-optic modulator 8, the first speculum 9, the second speculum 10, the 3rd speculum 11, the 4th speculum 12, first
Amici prism 13, the second Amici prism 14, the 5th speculum 15, the 3rd Amici prism 16, the first polarizer 17, the first photoelectricity are visited
Survey device 18, the 3rd polarization splitting prism 19, the 3rd quarter-wave plate 20, tested speculum 21, measured object the 22, the 4th 4/
One wave plate 23, reference mirror 24, the second polarizer 25, the 4th Amici prism 26, the second photodetector 27, ultra-narrow bandwidth filter
Piece 28, the 3rd polarizer 29, the 3rd photodetector 30, the 4th photodetector 31.
Specific measuring principle of the present utility model is described as follows：
As shown in figure 1, it is λ that laser 1 and laser 2 send wavelength respectively1=632.8nm and λ2=635nm linear polarization
Light, wherein wavelength X1Linearly polarized light to become the first circularly polarized light, wavelength λ after the first quarter-wave plate 32By
Become the second circularly polarized light after second quarter-wave plate 4, first, second circularly polarized light passes through the first polarization splitting prism respectively
5th, the beam splitting of the second polarization splitting prism 6.
First circularly polarized light beam splitting is first level polarised light and the first orthogonal polarized light, and first level polarised light passes through
One acousto-optic modulator 7 introduces f1=100MHz frequency displacement, it is vertical with the first of the 3rd speculum 11 of process by the first speculum 9
Polarised light closes beam at the first Amici prism 13, and now the frequency of first level polarised light is v1+f1, the first orthogonal polarized light
Frequency is v1, wherein v1For λ1Corresponding light frequency.
Second circularly polarized light beam splitting is the second horizontal polarization light and the second orthogonal polarized light, and the second horizontal polarization light is through second
In the second Amici prism 14 and the second vertical polarization through the reflection of the 4th speculum 12 after the speculum 10 of acousto-optic modulator 8 and second
Combiner, now the frequency of the second horizontal polarization light is v2+f2, the frequency of the second orthogonal polarized light is v2, wherein f2=
100.01MHz, v2For λ2Corresponding light frequency.
First level polarised light, the first orthogonal polarized light, the second horizontal polarization light and the beam laser of the second orthogonal polarized light four
Beam beam splitting is closed at the 3rd Amici prism 16；A portion light intensity passes through the first polarizer 17, and the first polarizer 17 is by four beams
The laser of different polarization is changed into polarization state identical linearly polarized light, and wherein frequency is v1And v1+f1Two beam laser coherences superposition,
Frequency is v2And v2+f2The superposition of two beam laser coherences, form the reference signal of dual wavelength superhet interference by the first photodetection
Device 18 receives.
Another four beams laser after beam splitting passes through the 3rd beam splitting again of polarization splitting prism 19, wherein the first level transmitted is inclined
Shake light and the second horizontal polarization light is changed into the 3rd circularly polarized light and the 4th circular polarization respectively after the 3rd quarter-wave plate 20
Light, which is impinged perpendicularly on tested speculum 21, to be reflected, again pass by the 3rd quarter-wave plate 20 be changed into the 3rd orthogonal polarized light and
4th orthogonal polarized light is reflected by the 3rd polarization splitting prism 19, wherein tested speculum 21 is connected on measured object 22；Reflection
The first orthogonal polarized light and the second orthogonal polarized light be referenced speculum 24 after the 4th quarter-wave plate 23 and reflect, then
It is secondary to be changed into the 3rd horizontal polarization light after the 4th quarter-wave plate 23 and the 4th horizontal polarization light passes through the 3rd polarization spectro
Prism 19；The wherein frequency of the 3rd orthogonal polarized light, the 4th orthogonal polarized light, the 3rd horizontal polarization light and the 4th horizontal polarization light
Respectively v1+f1、v2+f2、v1、v2, this four beams laser is two parts by the beam splitting of the 4th Amici prism 26；A part passes through second
Coherent superposition occurs for polarizer 25, and the measurement signal for forming the interference of dual wavelength superhet is received by the second photodetector 27.It is double
The reference signal of wavelength superhet interference and measured signal are subsequently calculated the phase change value for including displacement information, and phase becomes
Change value is with synthetic wavelength λsOn the basis of, therefore there is wide range and relatively low precision.
It is v that another part leaves behind frequency by ultra-narrow bandwidth filter piece 281+f1、v1The 3rd orthogonal polarized light and the 4th water
Flat polarised light, the wavelength of this two beams laser is all in λ1Near, thus can by ultra-narrow bandwidth filter piece 28, ultra-narrow bandwidth filter piece
Centre wavelength is 632.8nm, full width at half maximum 1nm.It is horizontal by the 3rd orthogonal polarized light of ultra-narrow bandwidth filter piece 28 and the 4th
Polarised light passes through the 3rd polarizer 29 again, and coherent superposition occurs, and forms Single wavelength interference signal and is connect by the 3rd photodetector 30
Receive.
4th photodetector 31 receives ambient light signal, for eliminating ambient light with Single wavelength interference signal difference
Influence.Single wavelength interference signal and environment OFF signal subsequently calculate the phase change value comprising displacement information, phase change value
With Single wavelength λ1On the basis of, therefore with high accuracy.
The utility model utilizes the measuring range of synthetic wavelength interference signal lifting system caused by dual wavelength so that system
Measuring range be much larger than the range of Single wavelength interference, and filtering is demodulated to output signal using superhet interferometric method, can
With the phase of direct measurement synthetic wavelength, measurement, while Single wavelength interference signal is adopted to obtain using ultra-narrow bandwidth filter piece in real time is realized,
Ensure the precision of Single wavelength interferometry while measuring range is expanded.
The utility model is described by embodiment, and any person skilled in the art all can be without prejudice to this reality
With under new spirit and scope, modifications and changes are carried out to above-described embodiment.Therefore, have such as in art logical
All equivalent modifications or change that normal skill is completed under without departing from the spirit disclosed in the utility model and technological thought,
It should be covered by claim of the present utility model.
Claims (5)
1. a kind of dual wavelength superhet interferes real-time displacement measuring system, it is characterised in that：Two lasers (1,2) send two beams
The laser of different wave length, incide polarization splitting prism after respective quarter-wave plate respectively per Shu Jiguang and be divided into level
Polarization and the two-way of vertical polarization：Wherein horizontal polarization passes through acousto-optic modulator and speculum back reflection successively all the way, vertically
Polarization passes through speculum back reflection all the way, and two respective reflected lights of speculum incide Amici prism and close beam output, close beam
Light contains the two-way output light that frequency is different and polarization direction is different；
Two-way output light incides the 3rd Amici prism (16) and closes Shu Bingfa beams estranged：A part of light after beam splitting is inclined by first
The piece (17) that shakes reaches the first photodetector (18), and another part light after beam splitting incides the 3rd polarization splitting prism (19) hair
Raw reflection and transmission, it is divided into the two-way of vertical polarization and horizontal polarization；
The light of the vertical polarization all the way reflected through the 3rd polarization splitting prism (19) passes through the 4th quarter-wave plate (23) quilt
The 4th quarter-wave plate (23) is again passed by after reference mirror (24) reflection to be changed into horizontal polarization light and return to the 3rd polarization
Amici prism (19)；The light of the horizontal polarization all the way transmitted through the 3rd polarization splitting prism (19) passes through the 3rd quarter-wave
Piece (20) again passes by the 3rd quarter-wave plate (20) and is changed into orthogonal polarized light and returns to after being reflected by tested speculum (21)
3rd polarization splitting prism (19), tested speculum (21) are fixed on measured object (22) surface；
The two-way laser for returning to the 3rd polarization splitting prism (19) incides the 4th after the 3rd polarization splitting prism (19) closes beam
Amici prism (26), reflection and transmission beam splitting occurs；A part for transmission is by the second polarizer (25) by the second photodetection
Device (27) receives, and the part of reflection is after ultra-narrow bandwidth filter piece (28) again through the 3rd polarizer (29) by the 3rd photodetection
Device (30) receives, and it is other that the 4th photodetector (31) is placed in the 3rd photodetector (30).
A kind of 2. dual wavelength superhet interference real-time displacement measuring system according to claim 1, it is characterised in that：It is described
Two lasers send the laser of different wave length, the wavelength difference of two beam laser is Δ λ.
A kind of 3. dual wavelength superhet interference real-time displacement measuring system according to claim 1, it is characterised in that：It is described
The light that sends of two lasers be different wave length linearly polarized light, be changed into two beam circularly polarized lights after quarter-wave plate,
It is the two mutually perpendicular linearly polarized lights in beam polarization direction to distinguish beam splitting after polarization splitting prism per beam circularly polarized light.
A kind of 4. dual wavelength superhet interference real-time displacement measuring system according to claim 1, it is characterised in that：It is described
Ultra-narrow bandwidth filter piece centre wavelength it is identical with less wavelength in the two-beam that two lasers are sent, full width at half maximum is less than
Δλ/2。
A kind of 5. dual wavelength superhet interference real-time displacement measuring system according to claim 1, it is characterised in that：It is described
The three, the 4th photodetector placement locations close to and towards identical.
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Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN109855743A (en) * | 2019-01-04 | 2019-06-07 | 北方工业大学 | Device and method for measuring large-size optical plane by double-frequency laser heterodyne interference phase |
| CN112737693A (en) * | 2020-12-25 | 2021-04-30 | 新沂市锡沂高新材料产业技术研究院有限公司 | Fundamental order radial polarization laser multiplexing equipment for large-capacity space communication |
| CN113865479A (en) * | 2021-09-02 | 2021-12-31 | 浙江理工大学 | Multi-wavelength interference absolute distance measuring device and method based on frequency division multiplexing |
-
2017
- 2017-05-26 CN CN201720602510.5U patent/CN207019624U/en active Active
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN109855743A (en) * | 2019-01-04 | 2019-06-07 | 北方工业大学 | Device and method for measuring large-size optical plane by double-frequency laser heterodyne interference phase |
| CN112737693A (en) * | 2020-12-25 | 2021-04-30 | 新沂市锡沂高新材料产业技术研究院有限公司 | Fundamental order radial polarization laser multiplexing equipment for large-capacity space communication |
| CN112737693B (en) * | 2020-12-25 | 2022-06-07 | 新沂市锡沂高新材料产业技术研究院有限公司 | Fundamental order radial polarization laser multiplexing equipment for large-capacity space communication |
| CN113865479A (en) * | 2021-09-02 | 2021-12-31 | 浙江理工大学 | Multi-wavelength interference absolute distance measuring device and method based on frequency division multiplexing |
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