CN204594416U - Modified cascade notch cuttype corner reflector laser interferometer - Google Patents
Modified cascade notch cuttype corner reflector laser interferometer Download PDFInfo
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- CN204594416U CN204594416U CN201520183838.9U CN201520183838U CN204594416U CN 204594416 U CN204594416 U CN 204594416U CN 201520183838 U CN201520183838 U CN 201520183838U CN 204594416 U CN204594416 U CN 204594416U
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Abstract
The utility model discloses a kind of modified cascade notch cuttype corner reflector laser interferometer, wherein interferometer comprises lasing light emitter, spectroscope, photodetector group, notch cuttype corner cube mirror group, mobile corner cube mirror and micromotion platform, wherein lasing light emitter comprises n collimated laser beam, n>=2, photodetector group comprises n photodetector, notch cuttype corner cube mirror group is composed of by m notch cuttype corner cube mirror and m-1 conventional right-angle catoptron, m>=2, the reflecting surface of each notch cuttype corner cube mirror is n the stepped appearance plane of reflection, adjacent two plane of reflection spacing are
k is natural number, notch cuttype corner cube mirror group connects micromotion platform.The laser interference phenomenon that this laser interferometer produces is not only relevant with optical maser wavelength, also relevant with stepped appearance plane of reflection height difference, by micromotion platform effect, the fraction part be not measured in laser interference ripple can be measured further, significantly improve measuring accuracy.
Description
Technical field
The utility model relates to a kind of Precision Inspection and instrument field, particularly a kind of modified cascade notch cuttype corner reflector laser interferometer.
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 is limited to optical maser wavelength, measuring accuracy is difficult to the deficiency promoted, a kind of modified cascade notch cuttype corner reflector laser interferometer is provided, this laser interferometer is on the basis of existing Michelson laser interferometer, adopt multiple light courcess notch cuttype corner cube mirror group, the measuring accuracy of this laser interferometer can be improved, simultaneously adaptive micromotion platform can obtain in laser interference process the fraction part being difficult to the interference wave measured, and can improve the measuring accuracy of this laser interferometer further.Simultaneously due to multi-pass interference state checker, there is higher antijamming capability to the environmental change of optical path.
In order to realize above-mentioned utility model object, the utility model provides following technical scheme:
A kind of modified cascade notch cuttype corner reflector laser interferometer, comprise lasing light emitter, spectroscope, notch cuttype corner cube mirror group, mobile corner cube mirror, photodetector group, micromotion platform, described lasing light emitter comprises n collimated laser beam, wherein n>=2, described photodetector group comprises n photodetector; Described notch cuttype corner cube mirror group comprises m notch cuttype corner cube mirror and m-1 conventional right-angle catoptron is composed of, wherein m>=2, the reflecting surface of each described notch cuttype corner cube mirror is n and becomes the step-like plane of reflection, and adjacent two described plane of reflection spacing are
wherein k is natural number, λ is the optical maser wavelength that lasing light emitter sends; In described notch cuttype corner cube mirror group, at least one notch cuttype corner cube mirror or conventional right-angle catoptron one end are connected with removable micromotion platform; The laser that described lasing light emitter sends is through described spectroscope, and every Shu Jiguang injects described notch cuttype corner cube mirror group respectively after reflection, reflects the laser light to corresponding each described photodetector after the internal reflection of described notch cuttype corner cube mirror group; The laser that described lasing light emitter sends is through described spectroscope, and every Shu Jiguang of direct transmission incides described mobile corner cube mirror back reflection respectively to corresponding each photodetector.
The laser beam quantity of this laser interferometer, the quantity of photodetector are n (n >=2), and be one_to_one corresponding, notch cuttype corner cube mirror group comprises m notch cuttype corner cube mirror and m-1 conventional right-angle catoptron is composed of, wherein each notch cuttype corner cube mirror has two reflective steps faces at a right angle, each reflective steps face comprises n the plane of reflection, the reflecting surface of conventional right-angle catoptron is two orthogonal planes, and notch cuttype corner cube mirror and conventional right-angle catoptron (abbreviation corner cube mirror) keep dislocation to be oppositely arranged to reflect.Therefore, every Shu Jiguang that lasing light emitter is launched is divided into two-way, wherein a road laser by dichroic mirror to notch cuttype corner cube mirror group, behind the reflective steps face and the reflection of conventional right-angle catoptron of all notch cuttype corner cube mirror inside, reflex to spectroscope at 45 ° again, after transmit and finally incide one of them photodetector on detector; Laser another road laser after transmission direct in spectroscope that this lasing light emitter is launched, spectroscope is reflexed to again after inciding mobile corner cube mirror, spectroscope reflects it to same photodetector again, this photodetector can detect this two-way optical path difference and be subjected to displacement in process whether produce interference state at mobile corner cube mirror, i.e. constructive interference or destructive interference.Because the plane of reflection on notch cuttype corner cube mirror becomes stairstepping, therefore each Shu Jiguang that lasing light emitter is launched is not identical by the light path of the light path after the cascaded surface reflection of notch cuttype corner cube mirror, the retardation values arrived after every Shu Jiguang that lasing light emitter is launched simultaneously is divided into two-way after corresponding photodetector is all not identical, the interference that this laser interferometer produces is not only relevant with the wavelength of laser, also there is relation with two plane of reflection height difference in reflective steps face, because adjacent two plane of reflection spacing h of this cascaded surface (i.e. the stepped appearance plane of reflection) equal
wherein k is natural number, λ is the optical maser wavelength that lasing light emitter sends, and this difference brings two of adjacent two planes of reflection bundle laser light path differences to be
one of them notch cuttype corner cube mirror re-shoots away through two secondary reflections, and the optical path difference of this two bundle laser after a notch cuttype corner cube mirror is
optical path difference after the notch cuttype corner cube mirror group that m notch cuttype corner cube mirror is formed is
because in optical path difference formula, k λ can't affect the interference state of this laser beam, only have
difference just can have an impact to the interference state of this laser beam, therefore, as long as mobile corner cube mirror generation relative displacement, move it distance equal or integral multiple in
distance, the photodetector on this detector just can detect that it is in the change of laser interference state, therefore the accuracy of detection of this laser interferometer then corresponding optical maser wavelength of bringing up to
can only accuracy of detection be for laser wavelength lambda relative to existing laser interferometer, this measuring accuracy is significantly improved, and namely this measuring accuracy is determined by the spacing (also can be described as height or thickness) of adjacent two planes of reflection in reflective steps face on notch cuttype corner cube mirror and the optical maser wavelength of lasing light emitter.
In addition, due at least one the notch cuttype corner cube mirror in notch cuttype corner cube mirror group or conventional right-angle catoptron being connected with micromotion platform, this micromotion platform refers to that very little displacement can occur for it, the micrometric displacement structure of precision Da Na meter, as being connected on micromotion platform when one of them notch cuttype corner cube mirror, micromotion platform is moved, and this bundle laser light path difference of this notch cuttype corner cube mirror group inside is the shift length of twice micromotion platform.When micromotion platform keeps motionless, during mobile corner cube mirror generation certain displacement, this photodetector can record length accuracy and be
the quantity of laser interference ripple, the precision now measured due to photodetector be integral multiple in
laser interference wave number amount, does not comprise and is less than
length thereof Δ d, this part also and and can not embody with the interference quantity of laser interference ripple, the reaction of distance d size that therefore the laser interference wave number amount of this measurement is corresponding be in fact in the actual distance that is subjected to displacement of mobile corner cube mirror integral multiple in
length thereof; When mobile corner cube mirror keeps motionless, micromotion platform is subjected to displacement, corresponding notch cuttype corner cube mirror also can be subjected to displacement, notch cuttype corner cube mirror after being subjected to displacement can change the light path of corresponding laser beam, two bundle laser light path differences thus received by photodetector change, the change of laser interference state can be produced, until photodetector detects when creating a laser interference wave number amount, micromotion platform stop motion, now can calculate being less than of mobile corner cube mirror displaced portion according to the distance that micromotion platform is subjected to displacement
the displacement Δ d of length.
Therefore, this laser interferometry instrument accurately can be measured and obtain mobile corner cube mirror displacement length more accurately, and its measuring accuracy can record and be less than
the displacement part of length, thus improve measuring accuracy.
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.
Preferably, on the reflective steps face of each notch cuttype corner cube mirror in described notch cuttype corner cube mirror group, the spacing of adjacent two planes of reflection is equal, is equal to
wherein λ is the optical maser wavelength that lasing light emitter sends.
On reflective steps face due to each notch cuttype corner cube mirror, the spacing of adjacent two planes of reflection equals
because incident angle is 45 degree, and have m notch cuttype corner cube mirror, the optical path difference of the two bundle laser that adjacent two planes of reflection that therefore can convert reflect is λ/n, as long as mobile corner cube mirror moves integral multiple in the distance of λ/2n, corresponding photodetector just can detect the interference situation of two-way laser, improves accuracy of detection.
Preferably, in described notch cuttype corner cube mirror group, all notch cuttype corner cube mirrors are all fixed on removable described micromotion platform, can move integrally notch cuttype corner cube mirror.
Preferably, described notch cuttype corner cube mirror group in groups comprises three, i.e. notch cuttype corner cube mirror one, notch cuttype corner cube mirror two, corner cube mirror three, wherein said notch cuttype corner cube mirror one, notch cuttype corner cube mirror two be arranged in parallel and are connected on described micromotion platform, and described corner cube mirror three is arranged relative to described notch cuttype corner cube mirror one, notch cuttype corner cube mirror two.
Preferably, described micromotion platform is piezoelectric ceramics.
Piezoelectric ceramics is a kind of ceramic material mechanical energy and electric energy can changed mutually, its deformation quantity produced under electric field action is very little, be no more than at most the micrometric displacement of 1/10000000th of size own, have repetitive distortion recovery capability, good stability, precision are high.
Preferably, the displacement size that the described piezoelectric ceramics surface connecting described notch cuttype corner cube mirror group produces is the optical maser wavelength of described lasing light emitter, and its displacement accuracy reaches nano-precision.
Preferably, n the laser beam that described lasing light emitter sends is equally spaced, and the spacing of adjacent two laser beam equals the integral multiple of optical maser wavelength.
Preferably, the spacing between adjacent two laser beam is 100-10000 optical maser wavelength doubly.
For improving the measuring accuracy of a kind of modified cascade of the utility model notch cuttype corner reflector laser interferometer further, the utility model also provides a kind of measuring method of above-mentioned a kind of modified cascade notch cuttype corner reflector laser interferometer, detect the fraction length of the laser interference ripple failing to measure, step comprises:
Step one, all notch cuttype corner cube mirror one end of described notch cuttype corner cube mirror group to be fixed on described micromotion platform, to adjust the position of described lasing light emitter, spectroscope, notch cuttype corner cube mirror group, mobile corner cube mirror, photodetector group;
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 corner cube mirror group, reflexes to corresponding described photodetector group through described notch cuttype corner cube mirror group; The laser that described lasing light emitter sends is to described spectroscope, laser after transmission incides described mobile corner cube mirror, reflex to described photodetector group through described mobile corner cube mirror, photodetector group can detect laser interference state, and optical interference circuit has adjusted;
Step 3, first described mobile corner cube mirror is fixed on the reference position of measurand, controls described micromotion platform and move, until one of them detects that phase long status or most weak laser interference state are interfered in most light laser in described photodetector group.Now fix described notch cuttype corner cube mirror group, by described mobile corner cube mirror at optical interference circuit direction displacement d, corresponding described photodetector records wavelength to be the quantity of the laser interference ripple of λ be N (i.e. the laser interference ripple that detects of n photodetector add up to N), now according to the displacement of the described mobile corner cube mirror of laser wavelength lambda calculating acquisition
Step 4, fixing described mobile corner cube mirror, control described micromotion platform to move, make moving along laser incident direction of all m described notch cuttype corner cube mirror, when in described photodetector group, one of them records a laser interference ripple again, now described micromotion platform displacement is l, then can obtain the distance length Δ d that described mobile corner cube mirror photodetector group in described step 3 is not detected is ml, thus, the displacement that can obtain mobile corner cube mirror described in step 3 more accurately value is
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 2ml 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 corner cube mirror displacement optical maser wavelength brings, i.e. 2 Δ d=2ml, so Δ d=ml, the displacement that therefore can obtain mobile corner cube mirror more accurately value is
When the direction that the sense of displacement of notch cuttype corner cube mirror is along laser reflection, the displacement l of its micromotion platform is equivalent to the light path 2ml 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 corner cube mirror displacement brings, just in time equal one and interfere wavelength
namely
therefore, the displacement of the mobile corner cube mirror that can be obtained by the method more accurately value is
Compared with prior art, the beneficial effects of the utility model:
1, the utility model overcomes existing laser interferometer and only can measure and obtain integral multiple wavelength in laser interference, measuring accuracy is difficult to the drawback promoted, on the basis of existing Michelson laser interferometer, in conjunction with micrometric displacement structure in laser interference light path, to obtain the fraction length being difficult to the laser interference ripple obtained in laser interference range finding, the measuring accuracy of further this laser interferometer of raising, easy to operate, calculate simple, good reliability.
2, the situation strictly meeting the alternately change of multi-pass interference state in measuring process is just counted it, 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.
Accompanying drawing illustrates:
Laser optical path schematic diagram when Fig. 1 is the use of the utility model modified cascade notch cuttype corner reflector laser interferometer;
Fig. 2 is the structural representation of lasing light emitter in Fig. 1;
Fig. 3 is the structural representation of notch cuttype corner cube mirror in Fig. 1.
Mark in figure:
1, lasing light emitter, 11, laser beam one, 12, laser beam two, 13, laser beam three, 14, laser beam four, 2, spectroscope, 3, notch cuttype corner cube mirror group, 31, notch cuttype corner cube mirror one, 32, notch cuttype corner cube mirror two, 33, corner cube mirror three, 4, mobile corner cube mirror, 5, photodetector group, 51, photodetector one, 52, photodetector two, 53, photodetector three, 54, photodetector four, 6, micromotion platform.
Embodiment
Below in conjunction with test example and embodiment, the utility model is described in further detail.But this should be interpreted as that the scope of the above-mentioned theme of the utility model is only limitted to following embodiment, all technology realized based on the utility model content all belong to scope of the present utility model.
As shown in Figure 1, a kind of modified cascade notch cuttype corner reflector laser interferometer, comprise lasing light emitter 1, spectroscope 2, notch cuttype corner cube mirror group 3, mobile corner cube mirror 4, photodetector group 5, micromotion platform 6, this lasing light emitter 1 comprises n collimated laser beam, wherein n>=2, photodetector group 5 comprises n photodetector equally, notch cuttype corner cube mirror group 3 comprises m notch cuttype corner cube mirror and m-1 conventional right-angle catoptron is composed of, wherein m>=2, each notch cuttype corner cube mirror comprises two orthogonal reflectings surface, each reflecting surface is the plane of reflection of n notch cuttype, adjacent two plane of reflection spacing are
(k is natural number).One end of notch cuttype corner cube mirror group 3 is connected with removable micromotion platform 6, the laser that lasing light emitter 1 sends is through spectroscope 2, every Shu Jiguang injects notch cuttype corner cube mirror group 3 respectively after reflection, corresponding each photodetector is reflected the laser light to after the internal reflection of notch cuttype corner cube mirror group 3, wherein the internal reflection of notch cuttype corner cube mirror group 3 is by notch cuttype corner cube mirror and conventional corner cube mirror alternating reflex, namely one of them notch cuttype corner cube mirror reflexes to another notch cuttype corner cube mirror after reflexing to conventional corner cube mirror again, then this notch cuttype corner cube mirror reflexes to the corner cube mirror of another routine again, the laser that lasing light emitter 1 sends is through spectroscope 2, and every Shu Jiguang of direct transmission incides mobile corner cube mirror 4 back reflection respectively to corresponding each photodetector.
As shown in Figure 2, four laser beam are equally spaced, and namely select n=4, are respectively laser beam 1, laser beam 2 12, laser beam 3 13, laser beam 4 14, and the spacing e of adjacent two laser beam equals the integral multiple of optical maser wavelength.Spacing e between adjacent two laser beam is 100-10000 optical maser wavelength doubly.If select adjacent two laser beam spacing e to be 10000 times of optical maser wavelength, then can select the optical maser wavelength of 663 nanometers, the spacing d of so adjacent two laser beam is 6.63 millimeters.Corresponding photodetector group 5 is also respectively four, i.e. photodetector 1, photodetector 2 52, photodetector 3 53, photodetector 4 54.
In addition, notch cuttype corner cube mirror group 3 in groups comprises three, i.e. notch cuttype corner cube mirror 1, notch cuttype corner cube mirror 2 32, corner cube mirror 3 33, wherein notch cuttype corner cube mirror 1, notch cuttype corner cube mirror 2 32 are connected on micromotion platform 6, can be subjected to displacement with micromotion platform 6, corner cube mirror 3 33 is then established relative to notch cuttype corner cube mirror, realizes the translation of light path with reverse.The reflective steps face of the notch cuttype corner cube mirror of each notch cuttype corner cube mirror group 3 is also corresponding to be comprised corresponding to four planes of reflection and lasing light emitter 1, photodetector group 5, as shown in Figure 3, four planes of reflection are selected to become stepped appearance 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, the one tunnel mirror 2 that is split is injected notch cuttype corner cube mirror group 3 and is reflected, namely four planes of reflection of notch cuttype corner cube mirror 1 will often restraint the plane of reflection of laser reflection to corner cube mirror 3 33 respectively, every Shu Jiguang is reflexed to notch cuttype corner cube mirror 2 32 again by the plane of reflection of corner cube mirror 3 33 respectively again, after finally being reflexed to spectroscope 2 by the plane of reflection of four on notch cuttype corner cube mirror 2 32, distinguish transmission again and incident light electric explorer 1, photodetector 2 52, photodetector 3 53, photodetector 4 54, another road of this laser is then direct incides mobile corner cube mirror 4 after spectroscope 2 transmission, after being reflected to spectroscope 2, spectroscope 2 again by this laser reflection to photodetector 1, photodetector 2 52, photodetector 3 53, photodetector 4 54.
Because notch cuttype corner cube mirror group 3 has selected two notch cuttype corner cube mirrors, therefore, each Shu Jiguang that lasing light emitter 1 sends is not identical by the light path of the light path after the reflective steps face reflection of notch cuttype corner cube mirror group 3, the retardation values arriving corresponding photodetector group 5 after every Shu Jiguang that lasing light emitter 1 sends simultaneously is divided into two-way is all not identical, phenomenon can be interfered not only relevant with the wavelength of laser, also and the level difference of cascaded surface have relation.
N=4 is selected, adjacent two plane of reflection height difference in the reflective steps face of each notch cuttype corner cube mirror in the present embodiment
the optical path difference △ d that can calculate the two bundle laser that adjacent two planes of reflection reflect is λ/4, therefore, as long as mobile corner cube mirror 4 carries out the distance of mobile λ/8 or integral multiple in the distance of λ/8, photodetector group on this detector 5 all has one of them to detect, and it is in most light laser interference state or most weak laser interference state, therefore the accuracy of detection of this laser interferometer then becomes λ/8, can only accuracy of detection be for laser wavelength lambda relative to existing laser interferometer, this measuring accuracy is significantly improved, namely this measuring accuracy is determined by the spacing (also can be described as height or thickness) of adjacent two notch cuttypes of the cascaded surface of the notch cuttype corner cube mirror of notch cuttype corner cube mirror group 3 and the optical maser wavelength of lasing light emitter 1.
When laser beam 1 be in the strongest interference state time, the retardation values after the laser that namely laser beam 1 sends is divided into two-way is integral multiple a
1λ, a
1for natural number, can the strongest interference state be measured by photodetector 1, now laser beam 2 12 to optical interference circuit, laser beam 3 13 to optical interference circuit and laser beam 4 14 the two-way retardation values of optical interference circuit is respectively: a
2λ-λ/4, a
3λ-λ/2, a
4λ-3 λ/4, a
2,a
3,a
4for natural number, three's light path is now all in the strongest non-interference state.
When mobile corner cube mirror 4 moves λ/8, the two-way laser retardation values that laser beam 1 is divided into increases λ/4, and other laser beam optical path difference △ d also corresponding increase λ/4 of lasing light emitter 1, now, the retardation values that the laser that laser beam 1 sends is divided into two-way is a
1λ+λ/4, are in the strongest non-interference state, and the retardation values that the laser that laser beam 2 12 sends is divided into two-way then becomes a
2λ, therefore photodetector 2 52 can detect that optical interference circuit will be in the strongest interference state, can measure it be in the strongest interference state by photodetector 2 52, and the laser of laser beam 3 13 and laser beam 4 14 is in the strongest non-interference state.When mobile corner cube mirror 4 moves λ/4, laser beam 3 13 will be in the strongest interference state to optical interference circuit, can measure the strongest interference state by photodetector 3 53.
Similar, when mobile corner cube mirror 4 moves 3 λ/8, when the two-way laser retardation values that laser beam 4 14 is divided into increases by 3 λ/4, laser light path difference also corresponding increase by 3 λ/4 of other laser beam, the retardation values that the laser that now laser beam 4 14 sends is divided into two-way then becomes a
4λ, the two-way light path that its laser beam is divided into will be in the strongest interference state, can measure the strongest interference state by photodetector 4 54.
Again, when mobile corner cube mirror 4 moves λ/2, when the two-way laser retardation values that laser beam 1 is divided into increases λ, the laser light path difference also corresponding increase λ of other laser beam, laser beam 1 will be in again the strongest interference state to optical interference circuit, can measure the strongest interference state by photodetector 1.Therefore, be just λ/8 for the measuring accuracy corresponding to the laser interferometer corresponding to four-step laser reflection structure, namely move corner cube mirror 4 displacement and be equal to or greater than λ/8, corresponding photodetector group 5 can either observe the interference state significant change of the light path of four laser that lasing light emitter 1 is launched.
The micromotion platform 6 of above-mentioned indication refers to that device of very little displacement can occur for it, and its mobile accuracy is nano-precision.
Preferably this micromotion platform 6 is piezoelectric ceramics.Piezoelectric ceramics is a kind of ceramic material mechanical energy and electric energy can changed mutually, its deformation quantity produced under electric field action is very little, be no more than at most the micrometric displacement of 1/10000000th of size own, have repetitive distortion recovery capability, good stability, precision are high.
For improving the measuring accuracy of a kind of modified cascade of the utility model notch cuttype corner reflector laser interferometer further, the utility model also provides a kind of measuring method of above-mentioned a kind of modified cascade notch cuttype corner reflector laser interferometer, detect and fail the fraction part of the laser interference ripple measured, step comprises:
Step one, by all notch cuttype corner cube mirrors of notch cuttype corner cube mirror group 3, namely notch cuttype corner cube mirror 1, notch cuttype corner cube mirror 2 32 one end are fixed on micromotion platform 6, adjust the position of lasing light emitter 1, spectroscope 2, notch cuttype corner cube mirror group 3, mobile corner cube mirror 4, photodetector group 5;
Step 2, startup lasing light emitter 1, the laser that lasing light emitter 1 sends reflects to spectroscope 2, and laser after reflection injects corresponding notch cuttype corner cube mirror group 3, reflexes to each photodetector in corresponding photodetector group 5 through notch cuttype corner cube mirror group 3; The laser that lasing light emitter 1 sends is to spectroscope 2, and the laser after transmission incides mobile corner cube mirror 4, and reflex to photodetector group 5 through mobile corner cube mirror 4, photodetector group 5 can detect laser interference state, and optical interference circuit has adjusted;
Step 3, first mobile corner cube mirror 4 is fixed on the reference position of measurand, control micromotion platform 6 to move, until one of them detects the strongest interference state of laser or the most weak interference state in photodetector group 5, now Fixed-order ladder type corner cube mirror group 3, mobile corner cube mirror 4 is at optical interference circuit direction displacement d, it be the quantity of the laser interference ripple of λ is N (the ading up to N of the laser interference ripple that n photodetector namely in photodetector group 5 detects) that corresponding photodetector group 5 records wavelength, the displacement obtaining mobile corner cube mirror 4 is now calculated according to laser wavelength lambda
Step 4, fixing mobile corner cube mirror 4, control micromotion platform 6 to move, as the direction displacement l that the moving direction of micromotion platform 6 is along laser incidence, be equivalent to the light path 4l 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 corner cube mirror 4 displacement optical maser wavelength brings, i.e. 2 Δ d=4l, so Δ d=2l, the displacement that therefore can obtain mobile corner cube mirror 4 more accurately value is
Because the moving direction of micromotion platform in above-mentioned steps four is the direction along laser incidence, so displacement l of its micromotion platform, be equivalent to the light path 4l 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 corner cube mirror 4 displacement optical maser wavelength brings, i.e. 2 Δ d=4l, so Δ d=2l, the displacement that therefore can obtain mobile corner cube mirror 4 more accurately value is
As shown in Figure 1, notch cuttype corner cube mirror group 3 includes notch cuttype corner cube mirror 1, notch cuttype corner cube mirror 2 32 and corner cube mirror 3 33, now m=2, wherein the plane of reflection of notch cuttype corner cube mirror 1 and notch cuttype corner cube mirror 2 32 is right angle cascaded surface, and the plane of reflection that corner cube mirror 3 33 is is right-angle plane.When the direction that the moving direction of micromotion platform 6 is along laser incidence, so displacement l of its micromotion platform 6, be equivalent to notch cuttype corner cube mirror 1 and notch cuttype corner cube mirror 2 32 moves distance l along laser incident direction, and corner cube mirror 3 33 keeps motionless, now add the light path 4l of 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 corner cube mirror 4 displacement optical maser wavelength brings, i.e. 2 Δ d=4l, so Δ d=2l, the displacement that therefore can obtain mobile corner cube mirror 4 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.
Above embodiment only in order to the utility model is described and and technical scheme described by unrestricted the utility model, although this instructions has been described in detail the utility model with reference to each above-mentioned embodiment, but the utility model is not limited to above-mentioned embodiment, therefore anyly the utility model is modified or equivalent to replace; And all do not depart from technical scheme and the improvement thereof of the spirit and scope of utility model, it all should be encompassed in the middle of right of the present utility model.
Claims (7)
1. a modified cascade notch cuttype corner reflector laser interferometer, comprise lasing light emitter (1), spectroscope (2), notch cuttype corner cube mirror group (3), mobile corner cube mirror (4), photodetector group (5), micromotion platform (6), it is characterized in that:
Described lasing light emitter (1) comprises n collimated laser beam, wherein n >=2, and described photodetector group (5) comprises n photodetector;
Described notch cuttype corner cube mirror group (3) comprises m notch cuttype corner cube mirror and m-1 conventional right-angle catoptron is composed of, wherein m>=2, the reflecting surface of each described notch cuttype corner cube mirror is n and becomes the step-like plane of reflection, and adjacent two described plane of reflection spacing are
wherein k is natural number, λ is the optical maser wavelength that lasing light emitter (1) sends;
In described notch cuttype corner cube mirror group (3), at least one notch cuttype corner cube mirror or conventional right-angle catoptron one end are connected with removable micromotion platform (6);
The laser that described lasing light emitter (1) sends is through described spectroscope (2), every Shu Jiguang injects described notch cuttype corner cube mirror group (3) respectively after reflection, reflects the laser light to corresponding each described photodetector after the internal reflection of described notch cuttype corner cube mirror group (3); The laser that described lasing light emitter (1) sends is through described spectroscope (2), and every Shu Jiguang of direct transmission incides described mobile corner cube mirror (4) back reflection respectively to corresponding each photodetector.
2. modified cascade notch cuttype corner reflector laser interferometer according to claim 1, it is characterized in that, work as k=0, on the reflective steps face of the notch cuttype corner cube mirror in described notch cuttype corner cube mirror group (3), the spacing of adjacent two planes of reflection is equal, is equal to
wherein λ is the optical maser wavelength that lasing light emitter (1) sends.
3. modified cascade notch cuttype corner reflector laser interferometer according to claim 1, it is characterized in that, in described notch cuttype corner cube mirror group (3), all notch cuttype corner cube mirrors are all fixed on removable described micromotion platform (6).
4. modified cascade notch cuttype corner reflector laser interferometer according to claim 3, it is characterized in that, described notch cuttype corner cube mirror group (3) comprises three, i.e. notch cuttype corner cube mirror one (31), notch cuttype corner cube mirror two (32), corner cube mirror three (33), wherein said notch cuttype corner cube mirror one (31), notch cuttype corner cube mirror two (32) be arranged in parallel and is connected on described micromotion platform (6), the relatively described notch cuttype corner cube mirror one (31) of described corner cube mirror three (33), notch cuttype corner cube mirror two (32) is arranged.
5., according to the arbitrary described modified cascade notch cuttype corner reflector laser interferometer of claim 1-4, it is characterized in that, described micromotion platform (6) is piezoelectric ceramics.
6. modified cascade notch cuttype corner reflector laser interferometer according to claim 5, it is characterized in that, n the laser beam that described lasing light emitter (1) is launched is equally spaced, and the spacing of adjacent two laser beam equals the integral multiple of optical maser wavelength.
7. modified cascade notch cuttype corner reflector laser interferometer according to claim 6, is characterized in that, the spacing between adjacent two laser beam that described lasing light emitter (1) sends is 100-10000 optical maser wavelength doubly.
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| CN201520183838.9U CN204594416U (en) | 2015-03-30 | 2015-03-30 | Modified cascade notch cuttype corner reflector laser interferometer |
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Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104697443A (en) * | 2015-03-30 | 2015-06-10 | 北方民族大学 | Motion-compensated cascade stepped reflection mirror laser interferometer and measurement method |
| CN105371754A (en) * | 2015-11-27 | 2016-03-02 | 成都信息工程大学 | Wavelength correction type multi-beam cascaded step angle reflecting mirror laser interferometer and measurement method thereof |
| CN113231733A (en) * | 2021-04-13 | 2021-08-10 | 深圳活力激光技术有限公司 | Laser beam combining device and processing equipment |
-
2015
- 2015-03-30 CN CN201520183838.9U patent/CN204594416U/en not_active Withdrawn - After Issue
Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104697443A (en) * | 2015-03-30 | 2015-06-10 | 北方民族大学 | Motion-compensated cascade stepped reflection mirror laser interferometer and measurement method |
| CN104697443B (en) * | 2015-03-30 | 2017-07-28 | 北方民族大学 | A kind of stepped corner reflector laser interferometer of motion compensation formula cascade and measuring method |
| CN105371754A (en) * | 2015-11-27 | 2016-03-02 | 成都信息工程大学 | Wavelength correction type multi-beam cascaded step angle reflecting mirror laser interferometer and measurement method thereof |
| CN105371754B (en) * | 2015-11-27 | 2018-02-02 | 成都信息工程大学 | A kind of measuring method that ladder corner reflector laser interferometer is cascaded using wavelength amendment type multiple beam |
| CN113231733A (en) * | 2021-04-13 | 2021-08-10 | 深圳活力激光技术有限公司 | Laser beam combining device and processing equipment |
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