CN204461344U - A kind of anti-interference notch cuttype planar reflector laser interference instrument - Google Patents
A kind of anti-interference notch cuttype planar reflector laser interference instrument Download PDFInfo
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- CN204461344U CN204461344U CN201520182494.XU CN201520182494U CN204461344U CN 204461344 U CN204461344 U CN 204461344U CN 201520182494 U CN201520182494 U CN 201520182494U CN 204461344 U CN204461344 U CN 204461344U
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Abstract
The utility model relates to laser interferometry techniques field, be specifically related to a kind of anti-interference notch cuttype planar reflector laser interference instrument, comprise lasing light emitter, spectroscope, notch cuttype plane mirror, mobile mirror, photodetector group and micromotion platform, the reflecting surface of notch cuttype plane mirror is n ladder plane, and adjacent two plane of reflection spacing are
(k is natural number), described lasing light emitter can generate multi beam parallel laser, and described photodetector group has n photodetector, in laser interferometry process, n photodetector will alternately be in the strongest interference state of laser or the most weak interference state, and measuring accuracy can reach
the situation strictly meeting the alternately change of multi-pass interference state in measuring process is just counted it simultaneously, namely in multi-pass interferometry, AC signal is introduced, the measurement of DC level in traditional laser interferometry is converted to the measurement of AC signal, improves the antijamming capability of interferometer.
Description
Technical field
The utility model relates to laser interferometry techniques field, is specifically related to a kind of anti-interference notch cuttype planar reflector laser interference instrument.
Background technology
The appearance of laser instrument, makes ancient interference technique be developed rapidly, and laser has that brightness is high, good directionality, monochromaticity and the feature such as coherence is good, and laser interferometry techniques is comparative maturity.Laser interferometry system is applied widely: the measurement of accurate length, angle is as the detection of linear scale, grating, gauge block, precision lead screw; Position detecting system in exact instrument is as the control of precision optical machinery, correction; Position detecting system in large scale integrated circuit specialized equipment and detecting instrument; Minute sized measurement etc.In most of laser interference length-measuring system, all have employed Michelson interferometer or similar light channel structure.
The light beam that single frequency laser interferometer sends from laser instrument, is divided into two-way by spectroscope after beam-expanding collimation, and reflects can be combined in spectroscope from stationary mirror and moving reflector respectively and produce interference fringe.When moving reflector moves, the light intensity change of interference fringe is converted to electric impulse signal by the photo-electric conversion element in receptacle and electronic circuit etc., after shaping, amplification, input up-down counter calculate overall pulse number, calculating formula L=N × λ/2 are pressed again by robot calculator, in formula, λ is optical maser wavelength (N is electric pulse sum), calculates the displacement L of moving reflector.When using single frequency laser interferometer, require that ambient atmosphere is in steady state (SS), various air turbulence all can cause DC level change and affect measurement result.
One of weakness of single frequency laser interferometer is exactly seriously affected by environment, and severe at test environment, when measuring distance is longer, this shortcoming is very outstanding.Its reason is that it is a kind of direct current measurement system, must have the drawback of the gentle level drift of direct current light.When laser interferometer moveable mirror moves, photelectric receiver can output signal, if signal has exceeded the triggering level of counter, will go on record, if and laser beam intensity changes, with regard to likely making photosignal make counter stop counting lower than the triggering level of counter, the main cause of laser intensity or interference signal Strength Changes is made to be air turbulence, lathe mist of oil, cutting swarf is on the impact of light beam, and skew or corrugated distortion occur result light beam.
Single frequency laser interferometer is owing to measuring the problem of structure, and its measuring accuracy is limited to the wavelength of laser, and its precision can only be generally the integral multiple of its wavelength, is difficult to promote again, and the change of measurement environment simultaneously has considerable influence to measurement result.Along with the requirement of commercial production to precision measurement is more and more higher, the measuring accuracy of surveying instrument is had higher requirement.
Utility model content
The purpose of this utility model is that overcoming existing laser interferometer measurement precision only can measure integral multiple wavelength in acquisition laser interference, measuring accuracy is difficult to the drawback promoted, on the basis of existing Michelson laser interferometer, multi beam collimated laser beam and notch cuttype plane mirror is adopted to realize alternately measuring of laser interference, simultaneously in laser interference light path in conjunction with micromotion platform, to obtain the fraction part of the laser interference ripple that cannot obtain in laser interference range finding, improve the measuring accuracy of laser interferometry instrument.Simultaneously due to multi-pass interference state checker, there is higher antijamming capability to the environmental change of optical path.
The technical solution adopted in the utility model is:
A kind of anti-interference notch cuttype planar reflector laser interference instrument, comprise lasing light emitter, spectroscope, notch cuttype plane mirror, mobile mirror, photodetector group and micromotion platform, described lasing light emitter comprises n collimated laser beam, wherein n>=2, described photodetector group comprises n photodetector, described notch cuttype plane mirror comprises the plane of reflection that n becomes notch cuttype, and the spacing of adjacent two planes of reflection equals
wherein k is natural number, λ is the optical maser wavelength that lasing light emitter sends; The laser that each described lasing light emitter sends, after described dichroic mirror, injects a corresponding plane of reflection respectively, and each described plane of reflection is by corresponding laser beam reflection each photodetector to corresponding described photodetector group; Every Shu Jiguang that described lasing light emitter sends, after described spectroscope transmission, reflexes to each photodetector of corresponding photodetector group again after inciding described mobile mirror respectively; Described notch cuttype plane mirror is connected on described micromotion platform.
As preferred implementation of the present utility model, described micromotion platform can be piezoelectric ceramics.
As preferred implementation of the present utility model, along with described mobile mirror is in the movement in optical interference circuit direction, due to the optical interference circuit optical path difference of the different laser of lasing light emitter injection, each laser interference light path alternately will be in the strongest interference state.
The utility model also provides a kind of measuring method of above-mentioned anti-interference notch cuttype planar reflector laser interference instrument, and step comprises:
Step one, described notch cuttype plane mirror to be fixed on described micromotion platform, to adjust the position of described lasing light emitter, spectroscope, notch cuttype plane mirror, mobile mirror, photodetector;
Step 2, start described lasing light emitter, the laser that described lasing light emitter sends is to described dichroic mirror, laser after reflection injects corresponding described notch cuttype plane mirror, at the ladder reflective surface of described notch cuttype plane mirror to the described photodetector of correspondence; The laser that described lasing light emitter sends is to described spectroscope, and the laser after transmission incides described mobile mirror, reflexes to described photodetector through described mobile mirror, and photodetector can detect laser interference state, and optical interference circuit has adjusted;
Step 3, first described mobile mirror is fixed on the initial measuring position of measurand, now control described micromotion platform to move, described notch cuttype plane mirror is moved along laser incident direction or reflection direction, when described photodetector records a laser interference ripple, i.e. the strongest interference state or the most weak interference state, fixing described micromotion platform.By described mobile mirror at optical interference circuit direction displacement d, it be the quantity of the laser interference ripple of λ is N (n photodetector detects laser interference ripple and add up to N) that corresponding described photodetector records wavelength, now calculates the displacement of the described mobile mirror of acquisition according to laser wavelength lambda
Step 4, fixing described mobile mirror, control described micromotion platform to move, make described notch cuttype plane mirror mobile in described laser incidence, when described photodetector records an interference wave again, i.e. the strongest interference state or the most weak interference state, now micromotion platform displacement is set to l, then the distance, delta d that tested distance is not detected is l, can obtain step 3 survey displacement d exact value be
Because the moving direction of micromotion platform in above-mentioned steps four is the direction along laser incidence, so the displacement l of its micromotion platform is equivalent to the light path 2l adding this beam laser, if another light beam light path amount 2 Δ d that the partial distance Δ d that the light path recruitment of this beam laser just in time equals to be less than in mobile mirror displacement optical maser wavelength brings, i.e. 2 Δ d=2l, so Δ d=l, the displacement that therefore can obtain mobile mirror more accurately value is
When the direction that the sense of displacement of notch cuttype plane mirror is along laser reflection, the displacement l of its micromotion platform is equivalent to the light path 2l decreasing this beam laser, if the light path reduction of this beam laser adds another light beam light path amount that the partial distance Δ d being less than optical maser wavelength in mobile mirror displacement brings, just in time equal one and interfere wavelength
namely
therefore, the displacement of the mobile mirror that can be obtained by the method more accurately value is
Owing to adopting multi-pass interferometry, in measuring process, the DC level that each photodetector detects should alternately change, if the DC level that the change of the measurement environment of a certain light path causes photodetector to measure offsets, and there is not alternately change in the DC level that the photodetector of other optical path detects, now think that this optical path is the impact being subject to measurement environment, ignore the change of its level.If the DC level that the change of the measurement environment of many light paths causes multiple photodetector to measure offsets, then think that measurement environment changes, ignore the change of its level.Only the situation strictly meeting the alternately change of multi-pass interference state in measuring process is just counted it, namely introduce AC signal in multi-pass interferometry, the measurement of DC level in traditional laser interferometry is converted to the measurement of AC signal.
In sum, owing to have employed technique scheme, the beneficial effects of the utility model are: the utility model overcomes existing laser interferometer measurement precision only can measure integral multiple wavelength in acquisition laser interference, measuring accuracy is difficult to the drawback promoted, on the basis of existing Michelson laser interferometer, multi beam collimated laser beam and notch cuttype plane mirror is adopted to realize alternately measuring of laser interference, simultaneously in laser interference light path in conjunction with micromotion platform, to obtain the fraction part of the laser interference ripple that cannot obtain in laser interference range finding, improve the measuring accuracy of laser interferometry instrument.
Accompanying drawing explanation
Fig. 1 is laser interferometry schematic diagram of the present utility model
Fig. 2 is the notch cuttype plane mirror schematic diagram that embodiment 1 adopts
Fig. 3 is lasing light emitter spacing schematic diagram
Fig. 4 is laser interference range measurement principle figure
Reference numeral: 1-lasing light emitter, 11-laser beam one, 12-laser beam two, 13-laser beam three, 14-laser beam four, 2-spectroscope, 3-micromotion platform, 4-notch cuttype plane mirror, 5-mobile mirror, 6-photodetector group, 61-photodetector one, 62-photodetector two, 63-photodetector three, mobile mirror measuring position, 64-photodetector four, 7-mobile mirror measuring position one, 8-two.
Embodiment
In order to make the purpose of this utility model, technical scheme and advantage clearly understand, below in conjunction with drawings and Examples, the utility model is described further.Should be appreciated that specific embodiment described herein only in order to explain the utility model, and be not used in restriction the utility model.
Embodiment 1
As shown in Figure 1, it is laser interferometry schematic diagram of the present utility model, the one anti-interference notch cuttype planar reflector laser interference instrument of the present embodiment, comprise lasing light emitter 1, spectroscope 2, micromotion platform 3, notch cuttype plane mirror 4, mobile mirror 5 and photodetector group (comprising photodetector 61 to 64), described lasing light emitter comprises n collimated laser beam, wherein n>=2, described photodetector group comprises n photodetector, described notch cuttype plane mirror comprises the plane of reflection that n becomes notch cuttype, and the spacing of adjacent two planes of reflection equals
wherein k is natural number, λ is the optical maser wavelength that lasing light emitter sends; The laser that each described lasing light emitter sends, after described dichroic mirror, injects a corresponding plane of reflection respectively, and each described plane of reflection is by corresponding laser beam reflection each photodetector to corresponding described photodetector group; Every Shu Jiguang that described lasing light emitter sends, after described spectroscope transmission, reflexes to each photodetector of corresponding photodetector group again after inciding described mobile mirror respectively; Described notch cuttype plane mirror is connected on described micromotion platform.
In the multi beam parallel laser that described lasing light emitter generates, the spacing of adjacent laser is the integral multiple of optical maser wavelength, and in accompanying drawing 3, four parallel lasers that lasing light emitter 1 penetrates, four parallel laser spacing h are identical, are optical maser wavelength integral multiple.Along with described mobile mirror is in the movement in optical interference circuit direction, due to the optical interference circuit optical path difference of the different laser of lasing light emitter injection, each laser interference light path alternately will be in the strongest interference state.
The laser interferometry principle of the utility model design as shown in Figure 1, the notch cuttype plane mirror that the utility model adopts as shown in Figure 2, lasing light emitter spacing as shown in Figure 3, lasing light emitter spacing is the optical maser wavelength of integral multiple, wherein piezoelectric ceramics is the preferred of micromotion platform, also can adopt other high precision micromotion platform.
For cutting down finished cost, preferred as one, the present embodiment adopts four-step catoptron, and select optical maser wavelength to be 663 nanometers, lasing light emitter spacing is 6.63 millimeters, and micromotion platform adopts piezoelectric ceramics.First go out anti-interference notch cuttype planar reflector laser interference instrument according to schematic diagram 1 fabrication design, according to Michelson laser interferometer adjustment method, laser interference light path is adjusted.Along with mobile mirror is in the movement in optical interference circuit direction, due to different laser interference light path optical path differences, each laser interference light path alternately will be in the strongest interference state, with regard to single laser interferometry light path, it is all the Michelson laser interference light path of standard, but due to different laser interference light path optical path differences, when light path corresponding to laser beam one be in the strongest interference state time, the strongest interference state of laser can be measured by photodetector 61, laser beam two to optical interference circuit, laser beam three to optical interference circuit and laser beam four will be in the strongest non-interference state to optical interference circuit.When mobile mirror moves
time, laser beam two will be in the strongest interference state to optical interference circuit, the strongest interference state of laser can be measured by photodetector 62.When mobile mirror moves
time, laser beam three will be in the strongest interference state to optical interference circuit, the strongest interference state of laser can be measured by photodetector 63.When mobile mirror moves
time, laser beam four will be in the strongest interference state to optical interference circuit, the strongest interference state of laser can be measured by photodetector 64.When mobile mirror moves
time, laser beam one will be in the strongest interference state again to optical interference circuit, the strongest interference state of laser can be measured by photodetector 61.For the measuring accuracy corresponding to the laser interferometer corresponding to 4 ladder plane mirror structures be just like this
increase step number and can improve measuring accuracy, the measuring accuracy corresponding to laser interferometer corresponding to 8 ladder laser reflection structures is just
but the step-thickness of notch cuttype plane mirror is just corresponding to be become
the rest may be inferred.
The utility model also provides a kind of measuring method of above-mentioned anti-interference notch cuttype planar reflector laser interference instrument, and step is as follows:
Step one, described notch cuttype plane mirror to be fixed on described micromotion platform, to adjust the position of described lasing light emitter, spectroscope, notch cuttype plane mirror, mobile mirror, photodetector;
Step 2, start described lasing light emitter, the laser that described lasing light emitter sends is to described dichroic mirror, laser after reflection injects corresponding described notch cuttype plane mirror, at the ladder reflective surface of described notch cuttype plane mirror to the described photodetector of correspondence; The laser that described lasing light emitter sends is to described spectroscope, and the laser after transmission incides described mobile mirror, reflexes to described photodetector through described mobile mirror, and photodetector can detect laser interference state, and optical interference circuit has adjusted;
Step 3, first described mobile mirror is fixed on the initial measuring position of measurand, now control described micromotion platform to move, described notch cuttype plane mirror is moved along laser incident direction or reflection direction, when described photodetector records a laser interference ripple, i.e. the strongest interference state or the most weak interference state, fixing described micromotion platform.By described mobile mirror at optical interference circuit direction displacement d, it be the quantity of the laser interference ripple of λ is N (n photodetector detects laser interference ripple and add up to N) that corresponding described photodetector records wavelength, now calculates the displacement of the described mobile mirror of acquisition according to laser wavelength lambda
Step 4, fixing described mobile mirror, control described micromotion platform to move, make described notch cuttype plane mirror mobile in described laser incidence, when described photodetector records an interference wave again, i.e. the strongest interference state or the most weak interference state, now micromotion platform displacement is set to l, then the distance, delta d that tested distance is not detected is l, can obtain step 3 survey displacement d exact value be
When the direction that the sense of displacement of notch cuttype plane mirror is along laser reflection, the displacement l of its micromotion platform is equivalent to the light path 2l decreasing this beam laser, if the light path reduction of this beam laser adds another light beam light path amount that the partial distance Δ d being less than optical maser wavelength in mobile mirror displacement brings, just in time equal one and interfere wavelength
namely
therefore, the displacement of the mobile mirror that can be obtained by the method more accurately value is
The utility model measuring process as shown in Figure 4.With mobile mirror measuring position 28, mobile mirror measuring position 1 shown in Fig. 4 represents that laser interferometer moves reference position and the final position of corner reflector when measuring relative length.
Owing to adopting multi-pass interferometry, in measuring process, the DC level that each photodetector detects should alternately change, if the DC level that the change of the measurement environment of a certain light path causes photodetector to measure offsets, and there is not alternately change in the DC level that the photodetector of other optical path detects, now think that this optical path is the impact being subject to measurement environment, ignore the change of its level.If the DC level that the change of the measurement environment of many light paths causes multiple photodetector to measure offsets, then think that measurement environment changes, ignore the change of its level.Only the situation strictly meeting the alternately change of multi-pass interference state in measuring process is just counted it, namely introduce AC signal in multi-pass interferometry, the measurement of DC level in traditional laser interferometry is converted to the measurement of AC signal.
The foregoing is only preferred embodiment of the present utility model; not in order to limit the utility model; all do within spirit of the present utility model and principle any amendment, equivalent to replace and improvement etc., all should be included within protection domain of the present utility model.
Claims (3)
1. an anti-interference notch cuttype planar reflector laser interference instrument, comprise lasing light emitter, spectroscope, notch cuttype plane mirror, mobile mirror, photodetector group and micromotion platform, it is characterized in that, described lasing light emitter comprises n collimated laser beam, wherein n>=2, described photodetector group comprises n photodetector, and described notch cuttype plane mirror comprises the plane of reflection that n becomes notch cuttype, and the spacing of adjacent two planes of reflection equals
wherein k is natural number, λ is the optical maser wavelength that lasing light emitter sends; The laser that each described lasing light emitter sends, after described dichroic mirror, injects a corresponding plane of reflection respectively, and each described plane of reflection is by corresponding laser beam reflection each photodetector to corresponding described photodetector group; Every Shu Jiguang that described lasing light emitter sends, after described spectroscope transmission, reflexes to each photodetector of corresponding photodetector group again after inciding described mobile mirror respectively; Described notch cuttype plane mirror is connected on described micromotion platform.
2. anti-interference notch cuttype planar reflector laser interference instrument according to claim 1, is characterized in that, described micromotion platform can be piezoelectric ceramics.
3. anti-interference notch cuttype planar reflector laser interference instrument according to claim 1, is characterized in that, in the multi beam parallel laser that described lasing light emitter generates, the spacing of adjacent laser is the integral multiple of optical maser wavelength.
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN111288896B (en) * | 2020-03-12 | 2021-01-05 | 华中科技大学 | Displacement detection system based on asymmetric interference structure and detection method thereof |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN111288896B (en) * | 2020-03-12 | 2021-01-05 | 华中科技大学 | Displacement detection system based on asymmetric interference structure and detection method thereof |
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