CN205245987U - Wavelength correction formula multiple beam ladder planar mirror laser interferometer - Google Patents
Wavelength correction formula multiple beam ladder planar mirror laser interferometer Download PDFInfo
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- CN205245987U CN205245987U CN201520969704.XU CN201520969704U CN205245987U CN 205245987 U CN205245987 U CN 205245987U CN 201520969704 U CN201520969704 U CN 201520969704U CN 205245987 U CN205245987 U CN 205245987U
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Abstract
The utility model discloses a wavelength correction formula multiple beam ladder planar mirror laser interferometer, including laser source, spectroscope, stationary mirror, measurement reflecting mirror device, photoelectric detector group, wherein the laser source includes the individual collimated laser beam of n (n >= 2), and photoelectric detector group is including a n photoelectric detector spare. Measuring reflecting mirror device and including measurement speculum and precise displacement device, the plane of reflection of stationary mirror is a n ladder plane, and two adjacent reflection plane intervals are 2 (k is the natural number) of lambda / 2n+k lambda /, every shu jiguang becomes two bundles behind the spectroscope, wherein a branch of spectroscope of following after the stationary mirror reflects passs through, arrives photoelectric detector, and another shujiguang also incides to this photoelectric detector after measurement speculum, spectroscope reflect in proper order simultaneously. This photoelectric detector group can detect the precision and reach lambda / other displacement of 2n level, adopts wavelength correcting method to obtain environment equivalence wavelength, is showing and is improving measurement accuracy.
Description
Technical field
The utility model relates to a kind of Precision Inspection and instrument field, particularly a kind of wavelength amendment type multiple beam ladder planar reflector laser interference instrument.
Background technology
The appearance of laser instrument, is developed rapidly ancient interference technique, and laser has that brightness is high, good directionality, monochromaticjty and feature, the comparative maturity of laser interferometry technology such as coherence is good. Laser interferometry system application is very extensive: the measurement of accurate length, angle is as the detection of linear scale, grating, gauge block, precision lead screw; Position detecting system in precision instrument is as the control of precision optical machinery, correction; Position detecting system in large scale integrated circuit special equipment and detecting instrument; Minute sized measurement etc. In most of laser interference length-measuring systems, Michelson's interferometer or similar light channel structure are all adopted.
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 and can be combined in spectroscope and produce interference fringe from stationary mirror and moving reflector respectively. In the time that moving reflector moves, the light intensity variation of interference fringe is converted to electric impulse signal by photo-electric conversion element and electronic circuit etc. in recipient, after shaping, amplification, input forward-backward counter and calculate overall pulse number, press calculating formula L=N × λ/2 by electronic computer again, in formula, λ is optical maser wavelength (N is electric pulse sum), calculates the displacement L of moving reflector. While using single frequency laser interferometer, require ambient atmosphere in stable state, various air turbulences all can cause DC level variation and affect measurement result.
One of weakness of single frequency laser interferometer is exactly affected by environment serious, and severe at test environment, when measuring distance is longer, this shortcoming is very outstanding. Its reason is that it is a kind of DC measurement system, must have the drawback of the gentle level drift of direct current light. When the movable reflective mirror of laser interferometer moves, photelectric receiver meeting output signal, if signal has exceeded the triggering level of counter, will go on record, if and laser beam intensity changes, just likely make photosignal make counter stop counting lower than the triggering level of counter, making the main cause of laser instrument intensity or interference signal Strength Changes is air turbulence, lathe mist of oil, the impact of cutting swarf on light beam, there is skew or corrugated distortion in result light beam.
Single frequency laser interferometer is owing to measuring the problem of structure, and its certainty of measurement is limited to sharp light wavelength, and its precision can only be generally the integral multiple of its wavelength, is difficult to promote again, and the variation of measurement environment simultaneously has considerable influence to measurement result. Along with industrial production is more and more higher to the requirement of accurate measurement, the certainty of measurement of measuring instrument is had higher requirement.
Summary of the invention
The object of the invention is to overcome existing laser interferometer measurement precision and be limited to optical maser wavelength, certainty of measurement is difficult to the deficiency promoting, a kind of wavelength amendment type multiple beam ladder planar reflector laser interference instrument and wavelength modification method are provided, this laser interferometer is on the basis of existing Michelson laser interferometer, adopt multiple light courcess multi-ladder plane mirror, can detect the precision of λ/2n for n ladder plane mirror, improve the certainty of measurement of laser interferometer. Laser effective wavelength under measurement environment can obtain by wavelength modification method of the present invention, has further improved the certainty of measurement of this laser interferometer. Due to multi-pass interference state checker, the environmental change of optical path is had to higher antijamming capability simultaneously.
In order to realize foregoing invention object, the invention provides following technical scheme:
A kind of wavelength amendment type multiple beam ladder planar reflector laser interference instrument, comprise lasing light emitter, spectroscope, stationary mirror, measurement reflector apparatus, photodetector group, it is characterized in that, described measurement reflector apparatus comprises measures speculum and accurate displacement device, described measurement speculum is arranged on described accurate displacement device, described accurate displacement device is arranged on testee, described accurate displacement device for described measurement speculum provide with testee displacement in the same way or reverse displacement. Described lasing light emitter comprises n collimated laser beam, wherein n >=2, described photodetector group comprises n photoelectric detector, the reflecting surface of described stationary mirror is n the plane of reflection that becomes notch cuttype, the spacing of adjacent two planes of reflection equals λ/2n+k λ/2, and wherein k is that random natural number, λ are the optical maser wavelength that lasing light emitter sends; Every Shu Jiguang that each described lasing light emitter sends, after described spectroscope reflection, vertically injects respectively a corresponding plane of reflection, and each described plane of reflection is each photoelectric detector of correspondence to described photodetector group by corresponding laser reflection; Every bundle laser beam that described lasing light emitter sends, after described spectroscope transmission, impinges perpendicularly on respectively described measurement speculum back reflection each corresponding photoelectric detector to photodetector group.
The collimated laser beam quantity that the lasing light emitter of this laser interferometer produces, the quantity of notch cuttype plane of reflection quantity and photoelectric detector is n (n >=2), and for corresponding one by one, the every Shu Jiguang that is lasing light emitter transmitting is divided into two-way, one road laser reflexes to by spectroscope after one of them plane of cascaded surface of stationary mirror, vertical reflection is to one of them photoelectric detector in photodetector group, another road laser straight is connected on after transmission, to incide in spectroscope measures after speculum vertical reflection to same photoelectric detector again, this photoelectric detector can detect this two-way optical path difference and whether produce the strongest interference state or the most weak interference state in measurement speculum is subjected to displacement process. owing to being notch cuttype reflecting surface on stationary mirror, so the light path of the light path after each Shu Jiguang of lasing light emitter transmitting reflects by the cascaded surface of stationary mirror is not identical, it is all not identical that every Shu Jiguang of simultaneously lasing light emitter transmitting is divided into the light path difference arriving after two-way after corresponding photoelectric detector, can interfere phenomenon not only relevant with sharp light wavelength, also there is relation with the level difference of the ladder plane of reflection, adjacent two level differences of this cascaded surface (being the notch cuttype plane of reflection) equal λ/2n+k λ/2, the height difference that is adjacent cascaded surface can be the same or different, because every Shu Jiguang is after each plane of reflection reflection, light path is difference to some extent, no matter the height difference of adjacent two planes of reflection is how many, its optical path difference is λ/n+k λ.
Because k λ in above-mentioned optical path difference formula can't affect the interference state of this beam laser, only have difference λ/n just can exert an influence to the interference state of this beam laser, therefore, carry out the distance of mobile λ/2n or integral multiple in the distance of λ/2n as long as measure speculum, one of them of photoelectric detector in this photodetector group can detect its laser interference state and reach the strongest interference state, therefore the accuracy of detection of this laser interferometer becomes λ/2n, can only accuracy of detection with respect to existing laser interferometer be for laser wavelength lambda, this certainty of measurement is significantly improved, this certainty of measurement is determined by the spacing (also can be described as height or thickness) of every two ladder planes of the cascaded surface of stationary mirror and the optical maser wavelength of lasing light emitter.
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 variation of the measurement environment of a certain light path causes photodetector to measure is offset, and the DC level that the photodetector of other optical path detects does not occur alternately to change, now think that this optical path is the impact that is subject to measurement environment, ignore its level and change. If the DC level that the variation of the measurement environment of many light paths causes multiple photodetectors to measure is offset, think that measurement environment changes, ignore its level and change. Only just it is counted for strictly meeting the situation that multi-pass interference state alternately changes in measuring process, be i.e. in multi-pass interferometry, introduce AC signal, the measurement of DC level in traditional laser interferometry is converted to the measurement of AC signal.
It should be noted that, adjacent two level differences equal λ/2n+k λ/2, and whether real decisions laser is in the most just difference λ/2n of strong interference state, and difference k λ/2nd of increase, in order to increase the height difference of adjacent two reflectings surface of cascaded surface.
Preferably, described stationary mirror comprises that plane mirror body and n-1 reflection sheet combine, and the thickness of each described reflection sheet is λ/2n+k λ/2, and wherein k is natural number.
This cascaded surface is superimposed upon on plane mirror body and is formed by n-1 reflection sheet, plane mirror body surface is laser interferometer normal mirror, wherein the thickness of each reflection sheet is λ/2n+k λ/2, k is natural number, and the thickness of each reflection sheet can be the same or different.
Preferably, each described reflection sheet thickness is λ/2n.
Preferably, described plane mirror body and n-1 the identical reflection sheet of the thickness body that is formed in one, the height error of two ladder planes that adjacent two reflection sheets of avoiding the reflection sheet of piecemeal to link together producing form.
In the application's such scheme, due to measurement speculum is arranged on accurate displacement device, and accurate displacement device is arranged on testee, in the time that testee is subjected to displacement, testee drives accurate displacement device, and then speculum is measured in drive, so, in the time that testee is subjected to displacement, in place moving past in journey, due to the variation of optical interference circuit light path, make, the laser interference state of corresponding light beam also changes thereupon, start before surveying work, start accurate displacement device, make to measure speculum and produce displacement, the direction of displacement of described measurement speculum and the direction of displacement of testee are on same straight line, in the time that any one photodetector in photodetector group detects the strongest constructive interference, stop accurate displacement device, and by all photodetector countings zero clearing in photodetector group, and then the displacement that starts to measure testee, in the interference state change procedure of corresponding laser beam, the total degree N of strong constructive interference of the corresponding optical interference circuits of all photodetectors register in photodetector group, when testee mobile end, while remaining static, photodetector group stops counting, now, make to measure speculum by accurate displacement device moves on the direction of displacement of testee, and observe photodetector group, in the time that any one photodetector in photodetector group detects the strongest constructive interference, stop accurate displacement device, and read the shift value △ L that accurate displacement device provides for measuring speculum.
If displacement △ L is identical with the direction of displacement of testee, the shift value L=N × λ of the actual generation of testee/(2n)+(λ/(2n)-△ L), wherein △ L < λ/(2n), in formula, λ is optical maser wavelength;
If displacement △ L is contrary with the direction of displacement of testee, the shift value L=N × λ of the actual generation of testee/(2n)+△ L, wherein △ L < λ/(2n), in formula, λ is optical maser wavelength.
So, pass through said structure, also measure and add in displacement detecting result exceeding 1/ (2n) individual optical maser wavelength part △ L in testee actual displacement, and then the measured displacement result obtaining of the laser interferometer that makes the application is more accurate, its accuracy, higher than 1/ (2n) individual optical maser wavelength, specifically depends on the displacement accuracy that accurate displacement device can provide.
As the application's preferred version, described accurate displacement device comprises support platform and is arranged on the drive unit in described support platform, described support platform matches with described testee, and described drive unit provides the displacement on testee direction of displacement for described measurement speculum.
As the application's preferred version, described drive unit is Piezoelectric drive unit.
In this programme, employing Piezoelectric drive unit can be by mechanical energy and the electric energy ceramic material of conversion mutually, its deformation quantity producing under electric field action is very little, be no more than at most the micro-displacement necessarily/of size own, there is good past complex deformation recovery capability, good stability, precision are high, have further improved accuracy and the reliability of the application's accurate displacement device.
As the application's preferred version, described accurate displacement device also comprises the first displacement piece being arranged in described support platform and is arranged on the second displacement piece in described the first displacement piece, described drive unit matches with described the first displacement piece, for described the first displacement piece provides the displacement along described support platform, described the first displacement piece has an inclined-plane tilting with respect to its direction of displacement, described the second displacement piece is slidably arranged on the inclined-plane of described the first displacement piece, described the second displacement piece can be slided along the inclined-plane of described the first displacement piece, between described the first displacement piece and the second displacement piece, be adjacent to and coordinate, described measurement speculum is arranged in described the second displacement piece, in described support platform, be also provided with restraint device, described restraint device limits described the second displacement piece along moving on described the first displacement piece direction of displacement, make in the time that the first displacement piece is driven by described drive unit and produces displacement, described the second displacement piece is driven and generation displacement by described the first displacement piece, and, the direction of displacement of the direction of displacement of described the second displacement piece and described the first displacement piece is perpendicular, the inclined-plane of described the first displacement piece and the angle of its direction of displacement are A degree, 0 < A < 45.
In the application's such scheme, drive unit matches with the first displacement piece, for the first displacement piece provides the displacement along support platform, the first displacement piece has an inclined-plane tilting with respect to its direction of displacement, the second displacement piece is slidably arranged on the inclined-plane of the first displacement piece, the second displacement piece can be slided along the inclined-plane of the first displacement piece, in the time that accurate displacement device is worked, drive unit provides certain displacement to promote the first displacement piece, now, because restraint device limits the second displacement piece along moving on the first displacement piece direction of displacement, make the direction of displacement of the second displacement piece and the direction of displacement of the first displacement piece perpendicular, so, the displacement of the second displacement piece and drive unit for the displacement that the first displacement piece provides relevant, also relevant with the angle of its direction of displacement to the inclined-plane of the first displacement piece.
, if the inclined-plane of the first displacement piece and the angle of its direction of displacement are A degree, when the displacement providing when drive unit is X, the displacement that the second displacement piece produces on perpendicular to the drive unit direction of motion is Y=Xtan (A), so, when included angle A is less than 45 while spending, a displacement that is less than X value will be obtained, in the time further reducing included angle A, displacement Y also reduces thereupon, so, make in the application's scheme, accurate displacement device is by changing the mode of precision with stroke, directly improve the precision of the application's accurate displacement device, also just further improved the certainty of measurement of the application's laser interferometer.
As the application's preferred version, between described the first displacement piece and described support platform, be also provided with the magnetic magnetic part of tool, described the second displacement piece has magnetic, described the second displacement piece and described magnetic part are that there is a natural attraction between the sexes state. Make the first displacement piece in the time being pushed, can keep fitting tightly with the second displacement piece, ensure the precision of the application's accurate displacement device, and then ensure the certainty of measurement of the application's laser interferometer.
As the application's preferred version, in described the second displacement piece, be also provided with flexible member. Make the first displacement piece in the time being pushed, can keep with the second displacement piece in contact condition, ensure the precision of the application's accurate displacement device, and then ensure the certainty of measurement of the application's laser interferometer.
As the application's preferred version, described the second displacement piece and described measurement speculum are integral type structure.
In such scheme, the second displacement piece is integral type structure with measuring speculum, that is to say, one reflecting surface is directly set in the second displacement piece, makes itself to form and measure speculum, so, simplify the structure of the application's laser interferometer, convenient debugging and use.
Although at present, also there is the device of measuring air refraction, atmospheric temperature, humidity and air pressure to single-point position are measured, by wavelength compensation formula, optical maser wavelength is revised, but it is merely able to local air to detect, and in the application's displacement measurement field, because its displacement is to carry out in a region, in this region, the each parameter of the air of each position all has difference, particularly there is the situations such as larger thermograde, moist gradient and barometric gradient, will have larger error with single-point parameter correction optical maser wavelength.
So, for these reasons, in this application, inventor provides a kind of optical maser wavelength modification method of laser interferometer, detects under current measurement environment, the environment effective wavelength λ ' of laser, and the effective wavelength that this λ ' value is current measurement environment, the problem of having brought so directly avoided zones of different air refraction difference, so, reduce the error that environmental factor is brought, and then further improved the certainty of measurement of the application's laser interferometer and measuring method thereof.
Disclosed herein as well is a kind of optical maser wavelength modification method that adopts above-mentioned laser interferometer, comprise the steps:
Steps A: adopting laser interferometer to carry out in the environment of displacement measurement, wavelength amendment type multiple beam ladder planar reflector laser interference instrument is installed;
Step B: measurement reflector apparatus is arranged on testee;
Step C: debugging wavelength amendment type multiple beam ladder planar reflector laser interference instrument, makes it form satisfactory light path, and make each optical interference circuit in interference state;
Step D: start accurate displacement device, make to measure speculum and move, in the time having any one the strongest constructive interference to be detected in photodetector group, stop accurate displacement device, and photodetector batch total is counted to zero clearing;
Step e: again start accurate displacement device, traverse measurement speculum, make in photodetector group all photodetectors register the total degree of strong constructive interference be M (M is positive integer), and read measurement speculum shift value Z corresponding to M constructive interference the strongest;
Step F: according to Z=(M × λ ')/(2n), n is photodetector number, draws under current measurement environment effective wavelength the λ '=2nZ/M of laser.
As the application's preferred version, in described step D and E, the strongest described constructive interference can also be the most weak destructive interference. In this programme, in optical maser wavelength makeover process, photodetector is the total degree that records in each laser interference light path the most weak destructive interference, the correction of the optical maser wavelength that so still can realize.
In such scheme, by detecting the effective wavelength λ ' in measurement environment, revise swashing light wavelength, so reduce the error that environmental factor is brought, and then further improved the certainty of measurement of the application's laser interferometer and measuring method thereof.
Compared with prior art, beneficial effect of the present invention:
(1) the laser beam quantity of the lasing light emitter of this high accuracy ladder plane reflection laser interferometer transmitting, the quantity of notch cuttype plane of reflection quantity and photoelectric detector is n (n >=2), and corresponding one by one, due to the light path difference of each Shu Jiguang of lasing light emitter transmitting light path after by Different Plane reflection on the cascaded surface of stationary mirror, it is all not identical that every Shu Jiguang of simultaneously lasing light emitter transmitting is divided into the light path difference arriving after two-way after corresponding photoelectric detector, whether each photoelectric detector can detect corresponding two-way laser can interfere phenomenon, the generation of this interference is not only relevant with sharp light wavelength, also there is relation with the level difference of cascaded surface, because adjacent two level differences of this cascaded surface equal λ/2n+k λ/2, therefore, carry out the distance of mobile λ/2n or integral multiple in the distance of λ/2n as long as measure speculum, photoelectric detector in this photodetector group can only one of them can detect it in light laser interference state, therefore the accuracy of detection of this laser interferometer is λ/2n, can only accuracy of detection with respect to existing laser interferometer be that for laser wavelength lambda, its certainty of measurement has obtained significant raising. simultaneously 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 variation of the measurement environment of a certain light path causes photodetector to measure is offset, and the DC level that the photodetector of other optical path detects does not occur alternately to change, now think that this optical path is the impact that is subject to measurement environment, ignore its level and change. if the DC level that the variation of the measurement environment of many light paths causes multiple photodetectors to measure is offset, think that measurement environment changes, ignore its level and change. only just it is counted for strictly meeting the situation that multi-pass interference state alternately changes in measuring process, be to introduce AC signal in multi-pass interferometry, the measurement of DC level in traditional laser interferometry is converted to the measurement of AC signal, has improved the antijamming capability of interferometer.
(2) by detecting the effective wavelength λ ' of laser in measurement environment, optical maser wavelength is revised, so, reduced the error that environmental factor is brought, and then further improved the certainty of measurement of the application's laser interferometer.
Brief description of the drawings:
Laser optical path schematic diagram when Fig. 1 is wavelength amendment type multiple beam ladder planar reflector laser interference instrument use of the present invention;
Fig. 2 is the structural representation of lasing light emitter in Fig. 1;
Fig. 3 is the structural representation of the notch cuttype plane of reflection of stationary mirror in Fig. 1;
Fig. 4 is for measuring speculum and the second displacement piece integral structure figure.
Mark in Fig. 1-4:
1, lasing light emitter, 11, laser beam one, 12, laser beam two, 13, laser beam three, 14, laser beam four, 2, spectroscope, 3, stationary mirror, 31, the plane of reflection one, 32, the plane of reflection two, 33, the plane of reflection three, 34, the plane of reflection four, 35, speculum body, 36, reflection sheet, 4, measure speculum, 5, photodetector group, 51, photoelectric detector one, 52, photoelectric detector two, 53, photoelectric detector three, 54, photoelectric detector four, 6, accurate displacement device, 7, measure speculum, 8, supporting platform, 9, drive unit, 10, restraint device, 11, magnetic part, 12, testee, 13, the first displacement piece, 14, the second displacement piece, 15, inclined-plane, 16, flexible member.
Detailed description of the invention
Below in conjunction with test example and detailed description of the invention, the present invention is described in further detail. But this should be interpreted as to the scope of the above-mentioned theme of the present invention only limits to following embodiment, all technology realizing based on content of the present invention all belong to scope of the present invention.
As shown in Figure 1, a kind of wavelength amendment type multiple beam ladder planar reflector laser interference instrument, comprise lasing light emitter 1, spectroscope 2, stationary mirror 3, measure reflector apparatus 4, photodetector group 5, described measurement speculum group 4 comprises measures speculum 7 and accurate displacement device 6, measure speculum 7 and comprise a plane of reflection, described measurement speculum 7 is arranged on described accurate displacement device 6, described accurate displacement device 6 is arranged on testee 12, described accurate displacement device 6 for described measurement speculum 7 provide with testee 12 displacements in the same way or reverse displacement,
Described lasing light emitter 1 comprises n collimated laser beam, n >=2, photodetector group 5 also comprises n photoelectric detector, the reflecting surface of stationary mirror 3 is n the notch cuttype plane of reflection, the spacing h of adjacent two ladder planes of reflection equals λ/2n+k λ/2, and wherein k is that natural number, λ are the optical maser wavelength that lasing light emitter 1 sends; Every bundle laser beam that lasing light emitter 1 sends, after spectroscope 2 reflections, is vertically injected respectively a corresponding reflection sheet 36, and every bundle laser reflection is arrived corresponding photoelectric detector by each reflection sheet 36; The corresponding laser beam that lasing light emitter 1 sends, after spectroscope 2 transmissions, impinges perpendicularly on respectively to measure after speculum 7 and reflexes to corresponding photoelectric detector again. It should be noted that, the λ in literary composition is the optical maser wavelength that lasing light emitter 1 sends, and every bundle optical maser wavelength that lasing light emitter 1 sends is all the same.
The laser beam quantity that the lasing light emitter 1 of this laser interferometer sends, the photoelectric detector quantity of cascaded surface plane quantity and photodetector group 5 is n (n >=2), and for corresponding one by one, be that every Shu Jiguang that lasing light emitter 1 is launched is divided into two-way, one road laser reflexes to by spectroscope 2 after one of them plane of cascaded surface of stationary mirror 3, be reflected back spectroscope 2 and reenter one of them photoelectric detector being mapped in photodetector group 5, another road laser straight is connected on to impinge perpendicularly on after the interior transmission of spectroscope 2 after measuring speculum 7 and reflexes to spectroscope 2 again, spectroscope 2 reflects it to same photoelectric detector again, this photoelectric detector can detect this two-way optical path difference and whether produce interference state in measurement speculum 7 is subjected to displacement process, be constructive interference or destructive interference. due to the cascaded surface on stationary mirror 3, so the light path of the light path after each Shu Jiguang that lasing light emitter 1 is launched reflects by the cascaded surface of stationary mirror 3 is not identical, it is all not identical that every Shu Jiguang that simultaneously lasing light emitter 1 is launched is divided into the light path difference arriving after two-way after corresponding photodetector group 5, can interfere phenomenon not only relevant with sharp light wavelength, also there is relation with the level difference of cascaded surface, because adjacent two level difference h of this cascaded surface equal λ/2n+k λ/2, therefore, carry out the distance of mobile λ/2n or integral multiple in the distance of λ/2n as long as measure speculum 7, photodetector group 5 on this photodetector all has one of them can detect it in light laser interference state, therefore the accuracy of detection of this laser interferometer becomes λ/2n, can only accuracy of detection with respect to existing laser interferometer be for laser wavelength lambda, this certainty of measurement is significantly improved, this certainty of measurement is determined by the spacing (also can be described as height or thickness) of adjacent two ladder planes of the cascaded surface of stationary mirror 3 and the optical maser wavelength of lasing light emitter 1.
This stationary mirror 3 comprises that plane mirror body 35 and n-1 the identical reflection sheet 36 of thickness h combine, and the thickness h of each described reflection sheet 36 is λ/2n. This cascaded surface is superimposed upon on plane mirror body 35 and is formed by n-1 the identical reflection sheet 36 of thickness h, and plane mirror body 35 is the laser interferometer normal mirror of surface for plane, and wherein the thickness h of each reflection sheet 36 is λ/2n. Meanwhile, this plane mirror body 35 and n-1 the identical reflection sheet 36 of the thickness h body that can be formed in one, the height error of two ladder planes that adjacent two reflection sheets 36 of avoiding the reflection sheet 36 of piecemeal to link together producing form.
As shown in Figure 2, n the laser beam that all lasing light emitters 1 send is equally spaced, now, select n=4, k=0, the laser beam that lasing light emitter 1 sends is respectively laser beam 1, laser beam 2 12, laser beam 3 13, laser beam 4 14, and the spacing d of adjacent two laser beams equals the integral multiple of optical maser wavelength. Select the optical maser wavelength of 663 nanometers, the spacing d of the adjacent laser beam that adjacent lasing light emitter 1 sends is 4 millimeters. The photoelectric detector that corresponding photodetector group 5 receives laser is also respectively four, i.e. photoelectric detector 1, photoelectric detector 2 52, photoelectric detector 3 53, photoelectric detector 4 54.
Now, the notch cuttype plane of reflection on stationary mirror 3 is also corresponding elects four as, be the plane of reflection 1, the plane of reflection 2 32, the plane of reflection 3 33, the plane of reflection 4 34, as shown in Figure 3, select four planes of reflection to become notch cuttype plane so that process and reduce costs. This light path route is that the laser that laser beam 1 sends is divided into two-way at spectroscope 2, stationary mirror 3 is incided after being reflected by spectroscope 2 in one tunnel, being reflected plane 1 reflexes to after spectroscope 2 transmission again and incides photoelectric detector 1, another road of this laser is directly incided and is measured speculum 7 after spectroscope 2 transmissions, be reflected to after spectroscope 2, spectroscope 2 again by this laser reflection to photoelectric detector 1. By that analogy, other laser beam 2 12, laser beam 3 13, laser beam 4 14 are reflected respectively plane 2 32, the plane of reflection 3 33, the plane of reflection 4 34 reflections, and are received by photoelectric detector 2 52, photoelectric detector 3 53, photoelectric detector 4 54 respectively. According to calculating, owing to having adopted four notch cuttype planes of reflection, the difference in height of adjacent two planes of reflection is λ/8, and the light path difference of the laser therefore sending by laser beam 1, laser beam 2 12, laser beam 3 13, laser beam 4 14 after stationary mirror 3 reflections is respectively a1λ、a2λ-λ/4、a3λ-λ/2、a4λ/4, λ-3, wherein a1、a2、a3、a4For natural number.
In the time that laser beam 1 is in the strongest interference state, the light path difference that the laser that laser beam 1 sends is divided into after two-way is a1λ, can measure laser in the strongest interference state by photoelectric detector 1, and now 2 12 of laser beams are respectively 4 14 two-way light path differences to optical interference circuit of optical interference circuit and laser beam 3 13 of optical interference circuits, laser beam: a2λ-λ/4、a3λ-λ/2、a4λ/4, λ-3, three's light path is now all in the strongest non-interference state.
Move λ/8 when measuring speculum 7, make the two-way laser light path difference value that lasing light emitter 1 is divided into increase λ/4 o'clock, the laser light path difference of other lasing light emitters is corresponding increase λ/4 also, and now, the light path difference that the laser that laser beam 1 sends is divided into two-way is a1λ+λ/4, in the strongest non-interference state, the light path difference that the laser that laser beam 2 12 sends is divided into two-way becomes a2λ, therefore photoelectric detector 2 52 can detect that optical interference circuit is in the strongest interference state, the laser of laser beam 3 13 and laser beam 4 14 is also in the strongest non-interference state. In the time that measurement speculum 7 moves λ/4,3 13 of laser beams will, in the strongest interference state, can be measured the strongest interference state of laser by photoelectric detector 3 53 to optical interference circuit.
Similarly, in the time that measurement speculum 7 moves 3 λ/8, make the two-way laser light path difference value that laser beam 1 is divided into increase by 3 λ/4 o'clock, the laser light path difference of other laser beams is corresponding increase by 3 λ/4 also, and the light path difference that the laser that now laser beam 4 14 sends is divided into two-way becomes a4λ, the two-way light path that its laser is divided into will, in constructive interference state, can be measured laser interference state by photoelectric detector 4 54.
Again, in the time that measurement speculum 7 moves λ/2, while making two-way laser light path difference value that laser beam 1 is divided into increase λ, the laser light path difference of other laser beams is corresponding increase λ also, one 11 of laser beams will, in the strongest interference state, can be measured the strongest interference state of laser by photoelectric detector 1 again to optical interference circuit. Therefore, be just λ/8 for the corresponding certainty of measurement of the corresponding laser interferometer of four-step planar laser catoptric arrangement, measure speculum 7 displacements and be equal to or greater than λ/8, corresponding photodetector group 5 can observe the interference state significant change of the light path of the four bundle laser that lasing light emitter 1 launches.
Therefore, the ladder plane of reflection quantity that increases stationary mirror 3 can improve certainty of measurement, when adopting the laser mirror structure of the 8 ladder planes of reflection, the corresponding certainty of measurement of corresponding laser interferometer is λ/16, in the time adopting stationary mirror 3 structure of the n ladder plane of reflection, the certainty of measurement of this laser interferometer is with regard to the corresponding λ/2n that becomes.
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 variation of the measurement environment of a certain light path causes photodetector to measure is offset, and the DC level that the photodetector of other optical path detects does not occur alternately to change, now think that this optical path is the impact that is subject to measurement environment, ignore its level and change. If the DC level that the variation of the measurement environment of many light paths causes multiple photodetectors to measure is offset, think that measurement environment changes, ignore its level and change. Only just it is counted for strictly meeting the situation that multi-pass interference state alternately changes in measuring process, be to introduce AC signal in multi-pass interferometry, the measurement of DC level in traditional laser interferometry is converted to the measurement of AC signal, has improved the antijamming capability of interferometer.
In the present embodiment, due to measurement speculum 7 is arranged on accurate displacement device 6, and accurate displacement device 6 is arranged on testee 12, in the time that testee 12 is subjected to displacement, testee 12 drives accurate displacement device 6, and then speculum 7 is measured in drive, so, in the time that testee 12 is subjected to displacement, in place moving past in journey, the interference state of each laser interference light path corresponding to laser interferometer of the present invention also changes thereupon, start before surveying work, start accurate displacement device 6, make to measure speculum 7 and produce displacement, the direction of displacement of the direction of displacement of described measurement speculum 7 and testee 12 is on same straight line, in the time that any one photodetector in photodetector group 5 detects the strongest constructive interference, stop accurate displacement device 6, and by all photodetector countings zero clearing in photodetector group 5, and then the displacement that starts to measure testee 12, in the interference state change procedure of corresponding each laser interference light path, the each photodetectors register of photodetector group 5 is the total degree N of strong constructive interference, when testee 12 mobile ends, while remaining static, photodetector group 5 stops counting, now, make to measure speculum 7 by accurate displacement device 6 moves on the direction of displacement of testee 12, and observe photodetector group 5, in the time that any one photodetector in photodetector group 5 detects the strongest constructive interference, stop accurate displacement device 6, and read the shift value △ L that accurate displacement device 6 provides for measuring speculum 7.
If displacement △ L is identical with the direction of displacement of testee 12,, actual shift value L=N × λ/(2n)+(λ/(the 2n)-△ L) producing of testee 12, wherein △ L < λ/(2n), in formula, λ is optical maser wavelength;
And, if displacement △ L is contrary with the direction of displacement of testee 12,, actual shift value L=N × λ/(the 2n)+△ L producing of testee 12, wherein △ L < λ/(2n), in formula, λ is optical maser wavelength.
So, pass through said structure, the part △ L that exceeds laser wavelength lambda/(2n) in testee 12 actual displacements is also measured and added in displacement detecting result, and then the measured displacement result obtaining of the laser interferometer that makes the application is more accurate, its precision, higher than half optical maser wavelength, specifically depends on 6 displacement accuracies that can provide of accurate displacement device.
Embodiment 2,
As shown in Fig. 1,4, laser interferometer as described in Example 1, described accurate displacement device 6 comprises support platform 8 and is arranged on the drive unit 9 in described support platform 8, described support platform 8 matches with described testee 12, described drive unit 9 provides the displacement on testee 12 direction of displacement for described measurement speculum 7, and described drive unit 9 is Piezoelectric drive unit.
In the present embodiment, the Piezoelectric drive unit 9 adopting is can be by mechanical energy and the electric energy ceramic material of conversion mutually, its deformation quantity producing under electric field action is very little, be no more than at most the micro-displacement necessarily/of size own, there is good past complex deformation recovery capability, good stability, precision are high, have further improved the precision of accurate displacement device 6 in the present embodiment.
Embodiment 3,
As Fig. 1, shown in 4, laser interferometer as described in Example 2, described accurate displacement device 6 also comprises and is arranged on the first displacement piece 13 in described support platform 8 and is arranged on the second displacement piece 14 in described the first displacement piece 13, described drive unit 9 matches with described the first displacement piece 13, for described the first displacement piece 13 provides along the displacement of described support platform 8, described the first displacement piece 13 has an inclined-plane 15 tilting with respect to its direction of displacement, described the second displacement piece 14 is slidably arranged on the inclined-plane 15 of described the first displacement piece 13, described the second displacement piece 14 can be slided along the inclined-plane of described the first displacement piece 13 15, between described the first displacement piece 13 and the second displacement piece 14, be adjacent to and coordinate, described measurement speculum 7 is arranged in described the second displacement piece 14, in described support platform 8, be also provided with restraint device 10, described restraint device 10 limits described the second displacement piece 14 along moving on described the first displacement piece 13 direction of displacement, make in the time that the first displacement piece 13 is driven by described drive unit 9 and produces displacement, described the second displacement piece 14 is driven by described the first displacement piece 13 and produces displacement, and, the direction of displacement of the direction of displacement of described the second displacement piece 14 and described the first displacement piece 13 is perpendicular, the inclined-plane 15 of described the first displacement piece 13 is A degree with the angle of its direction of displacement, preferably 0 < A < 45.
In an embodiment, drive unit 9 matches with the first displacement piece 13, for the first displacement piece 13 provides along the displacement of support platform 8, the first displacement piece 13 has an inclined-plane 15 tilting with respect to its direction of displacement, the second displacement piece 14 is slidably arranged on the inclined-plane 15 of the first displacement piece 13, the second displacement piece 14 can be slided along the inclined-plane of the first displacement piece 13 15, in the time that accurate displacement device 6 is worked, drive unit 9 provides certain displacement to promote the first displacement piece 13, now, because restraint device 10 limits the second displacement piece 14 along moving on the first displacement piece 13 direction of displacement, make the direction of displacement of the second displacement piece 14 and the direction of displacement of the first displacement piece 13 perpendicular, so, the displacement of the second displacement piece 14 and drive unit 9 for the displacement that the first displacement piece 13 provides relevant, also relevant with the angle of its direction of displacement to the inclined-plane 15 of the first displacement piece 13.
That is, establish the inclined-plane 15 of the first displacement piece 13 and the angle of its direction of displacement is A degree, when the displacement providing when drive unit 9 is X, the displacement that the second displacement piece 14 produces on perpendicular to drive unit 9 directions of motion is Y=Xtan (A). Preferably, when included angle A is less than 45 while spending, a displacement that is less than X value will be obtained, in the time further reducing included angle A, displacement Y also reduces thereupon, so, make in the present embodiment, accurate displacement device 6, by change the mode of precision with stroke, has directly improved the precision of the present embodiment accurate displacement device 6, has also just further improved the certainty of measurement of the present embodiment laser interferometer.
Embodiment 4,
As shown in Figure 4, laser interferometer as described in Example 3, between described the first displacement piece 13 and described support platform 8, be also provided with the magnetic magnetic part 11 of tool, described the second displacement piece 14 has magnetic, described the second displacement piece 14 and described magnetic part 11 be that there is a natural attraction between the sexes state, described the second displacement piece 14 and described measurement speculum 7 are integral type structure. Make the first displacement piece 13 in the time being pushed, measuring speculum 7 can keep fitting tightly with the second displacement piece 14, ensure the precision of the application's accurate displacement device 6, and then ensure the certainty of measurement of the application's laser interferometer, the second displacement piece 14 is integral type structure with measuring speculum 7, that is to say, directly in the second displacement piece 14, a reflecting surface is set, makes itself to form and measure speculum 7, so, simplify the structure of the present embodiment laser interferometer, convenient debugging and use.
Embodiment 5
Laser interferometer as described in Example 3, described the second displacement piece 14 is also provided with has flexible member 16, make the first displacement piece 13 in the time being pushed, can keep with the second displacement piece 14 in contact condition, ensure the precision of the application's accurate displacement device, and then ensure the certainty of measurement of the application's laser interferometer.
Embodiment 6
As Figure 1-4, a kind of optical maser wavelength modification method that adopts embodiment 1-5 any one laser interferometer, comprises the steps:
Steps A: adopting laser interferometer to carry out in the environment of displacement measurement, wavelength amendment type multiple beam ladder planar reflector laser interference instrument is installed;
Step B: measurement reflector apparatus 4 is arranged on testee 12;
Step C: debugging wavelength amendment type multiple beam ladder planar reflector laser interference instrument, makes it form satisfactory light path, and make each optical interference circuit in interference state;
Step D: start accurate displacement device 6, make to measure speculum 7 and move, in the time having any one the strongest constructive interference to be detected in photodetector group 5, stop accurate displacement device, and photodetector batch total is counted to zero clearing;
Step e: again start accurate displacement device, traverse measurement speculum, make in photodetector group all photodetectors register the total degree of strong constructive interference be M (M is positive integer), and read measurement speculum shift value Z corresponding to M constructive interference the strongest;
Step F: according to Z=(M × λ ')/(2n), n is photodetector number, draws under current measurement environment effective wavelength the λ '=2nZ/M of laser.
Although at present, also there is the device of measuring air refraction, atmospheric temperature, humidity and air pressure to single-point position are measured, by wavelength compensation formula, optical maser wavelength is revised, but it is merely able to local air to detect, and in the application's displacement measurement field, because its displacement is to carry out in a region, in this region, the each parameter of the air of each position all has difference, particularly there is the situations such as larger thermograde, moist gradient and barometric gradient, will have larger error with single-point parameter correction optical maser wavelength.
So, for these reasons, in this application, inventor provides a kind of optical maser wavelength modification method of laser interferometer, detects under current measurement environment, the environment effective wavelength λ ' of laser, and the effective wavelength that this λ ' value is current measurement environment, the problem of having brought so directly avoided zones of different air refraction difference, so, reduce the error that environmental factor is brought, and then further improved the certainty of measurement of the application's laser interferometer and measuring method thereof.
Embodiment 7
As Figure 1-4, wavelength modification method as described in Example 6, described step D is to step e, and the strongest described constructive interference can also be the most weak destructive interference.
Above embodiment is only in order to illustrate the present invention and unrestricted technical scheme described in the invention, although this description has been described in detail the present invention with reference to each above-mentioned embodiment, but the present invention is not limited to above-mentioned detailed description of the invention, therefore any the present invention is modified or is equal to replacement; And all do not depart from technical scheme and the improvement thereof of the spirit and scope of invention, it all should be encompassed in the middle of claim scope of the present invention.
Claims (3)
1. a wavelength amendment type multiple beam ladder planar reflector laser interference instrument, comprise lasing light emitter, spectroscope, stationary mirror, measure reflector apparatus, photodetector group, it is characterized in that, described measurement reflector apparatus comprises measures speculum and accurate displacement device, described measurement speculum is arranged on described accurate displacement device, described accurate displacement device is arranged on testee, described accurate displacement device for described measurement speculum provide with testee displacement in the same way or reverse displacement, described lasing light emitter comprises n collimated laser beam, wherein n >=2, described photodetector group comprises n photoelectric detector, the reflecting surface of described stationary mirror is n the plane of reflection that becomes notch cuttype, the spacing of adjacent two planes of reflection equals λ/2n+k λ/2, wherein k is natural number, λ is the optical maser wavelength that lasing light emitter (1) sends, the laser that each described lasing light emitter sends, after described spectroscope reflection, is vertically injected a corresponding plane of reflection, and each described plane of reflection reflexes to corresponding laser beam each photoelectric detector of corresponding described photodetector group, every Shu Jiguang that described lasing light emitter sends, after described spectroscope transmission, impinges perpendicularly on respectively described measurement speculum back reflection each photoelectric detector to corresponding photodetector group,
Described accurate displacement device comprises support platform and is arranged on the drive unit in described support platform, described support platform matches with described testee, described drive unit provides the displacement on testee direction of displacement for described measurement speculum, described drive unit is Piezoelectric drive unit, also comprise the first displacement piece being arranged in described support platform and be arranged on the second displacement piece in described the first displacement piece, described drive unit matches with described the first displacement piece, for described the first displacement piece provides the displacement along described support platform, described the first displacement piece has an inclined-plane tilting with respect to its direction of displacement, described the second displacement piece is slidably arranged on the inclined-plane of described the first displacement piece, described the second displacement piece can be slided along the inclined-plane of described the first displacement piece, between described the first displacement piece and the second displacement piece, be adjacent to and coordinate, described measurement speculum is arranged in described the second displacement piece, in described support platform, be also provided with restraint device, described restraint device limits described the second displacement piece along moving on described the first displacement piece direction of displacement, make in the time that the first displacement piece is driven by described drive unit and produces displacement, described the second displacement piece is driven and generation displacement by described the first displacement piece, and, the direction of displacement of the direction of displacement of described the second displacement piece and described the first displacement piece is perpendicular, the inclined-plane of described the first displacement piece and the angle of its direction of displacement are A degree, 0 < A < 45, in described the second displacement piece, be provided with flexible member, make the second displacement piece and the first displacement piece keep in touch state.
2. wavelength amendment type multiple beam ladder planar reflector laser interference instrument as claimed in claim 1, it is characterized in that, between described the first displacement piece and described support platform, be also provided with the magnetic magnetic part of tool, described the second displacement piece has magnetic, described the second displacement piece and described magnetic part are that there is a natural attraction between the sexes state.
3. wavelength amendment type multiple beam ladder planar reflector laser interference instrument as claimed in claim 2, is characterized in that, described the second displacement piece and described measurement speculum are integral type structure.
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN105371755A (en) * | 2015-11-27 | 2016-03-02 | 成都信息工程大学 | Wavelength correction type multi-beam step plane reflecting mirror laser interferometer and wavelength correction method |
| CN106017512A (en) * | 2016-08-10 | 2016-10-12 | 西安理工大学 | Digital level system calibrating device and calibrating method thereof |
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Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN105371755A (en) * | 2015-11-27 | 2016-03-02 | 成都信息工程大学 | Wavelength correction type multi-beam step plane reflecting mirror laser interferometer and wavelength correction method |
| CN105371755B (en) * | 2015-11-27 | 2018-02-06 | 成都信息工程大学 | A kind of optical maser wavelength modification method using wavelength amendment type multiple beam ladder planar reflector laser interference instrument |
| CN106017512A (en) * | 2016-08-10 | 2016-10-12 | 西安理工大学 | Digital level system calibrating device and calibrating method thereof |
| CN106017512B (en) * | 2016-08-10 | 2019-01-11 | 西安理工大学 | A kind of digital level system calibration device and calibration method |
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