CN101464139B - 1152nm wavelength helium neon laser nano-measuring tape - Google Patents
1152nm wavelength helium neon laser nano-measuring tape Download PDFInfo
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- CN101464139B CN101464139B CN2009100763083A CN200910076308A CN101464139B CN 101464139 B CN101464139 B CN 101464139B CN 2009100763083 A CN2009100763083 A CN 2009100763083A CN 200910076308 A CN200910076308 A CN 200910076308A CN 101464139 B CN101464139 B CN 101464139B
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Abstract
A nanometer measuring tape for helium-neon lasers with the wavelength of 1152 nm belongs to the technical field of laser-based displacement sensing, and is characterized in that the prior helium-neon laser with the wavelength being 632.8 nm is substituted for the helium-neon laser with the wavelength being 1152 nm to serve as the core of a nanometer measuring tape, so that the measuring range of the displacement is increased from 50 nm to higher than 100 nm under the condition that the resolution ratio (10 nm) remains unchanged. As the helium-neon laser with the wavelength being 1152 nm has higher gain, gain can be kept greater than loss when the inner cavity of the laser is exposed to air, therefore, the non-contact measurement of the separation between a gain pipe and a target lens is realized. By adopting a cat' s eye reflector as a target lens to be stuck with a target to be measured and designing the nanometer measuring tape into two structures with a full outer cavity and a semi-outer cavity respectively, the system has stronger stability, thereby becoming a steady and practical displacement sensor.
Description
Technical field:
The present invention relates to a kind of 1152nm wavelength helium neon laser nano and survey chi, belong to the laser displacement field of sensing technologies.
Background technology
(application number: multiple laser physics phenomenons such as 99103514.3) division of comprehensive utilization laser frequency, mode of laser are competed, laser power is tuning are transformed into a kind of displacement sensing instrument with self calibrating function with a common helium-neon laser to Chinese patent " displacement self-sensing helium-neon laser system and its implementation ".This method has the range of 12mm, the displacement measurement resolution of λ/8 (for the 632.8nm wavelength helium neon laser, λ/8 are 79.1nm).The agent structure of this invention is 632.8nm wavelength half external cavity helium neon laser, and one of its two reflecting cavity mirrors are fixed on linear guide rail (measuring staff) as index glass and go up to avoid optical cavity off resonance when laser optical axis axially moves.Chinese patent " is made the displacement self-sensing helium-neon laser system of chamber mirror " with opal (application number: 200310115540.6) this system is improved; Cat ' s eye reflector is connected as chamber mirror and line slideway; Improve the stability of system, widened its application.Chinese patent " nano laser is surveyed chi and realized the divided method of nano measurement " (application number: 200410088819.4) utilize system can be traceable to the characteristic and the self calibration ability of optical wavelength; Adopt the method for the big number of meter, survey decimal; Through increasing a precision micro-displacement sensor piezoelectric ceramics (PZT) and appropriate signals treatment circuit; The resolution of original system is increased to 10nm, and measurement range is increased to 50mm.But if require range further to improve, perhaps realizing non-cpntact measurement, is that the displacement transducer of core can't reach with the helium-neon laser of 632.8nm wavelength.Because the restriction on the principle,, make the signal processing system can't operate as normal if range increases the phenomenon that two longitudinal modes, four frequencies even three longitudinal modes, six frequencies can appear in back laser; The linearity that the chamber mirror moved when the measuring staff structure of employing stage clip also can't guarantee to move on a large scale is so the expansion of range is restricted.Because wavelength is that the gain of helium-neon laser of 632.8nm is less, when a chamber mirror is moved with target object as the target mirror, the phenomenon that can not export laser that caused less than loss by laser gain can appear, so be difficult to realize non-cpntact measurement.
Summary of the invention
The purpose of this invention is to provide a kind of 1152nm wavelength helium neon laser nano and survey chi,, further increase the range of displacement self-sensing helium-neon laser system, and realize non-cpntact measurement, thereby widen its application keeping under the prerequisite of former resolution.
The invention is characterized in that it is a full outside cavity gas laser of He-Ne that is operated in the 1152nm wavelength, comprises:
Laser gain pipe, in fill the He-Ne mixed gas;
Be installed in the anti-reflection window of 1152nm wavelength of these laser gain pipe both sides respectively along optical axis direction; The periphery of the anti-reflection window of this 1152nm wavelength is equipped with afterburning ring; Constitute a stress birefringence element, become single-frequency laser double-frequency laser with two orthogonal polarization orientation;
1152nm wavelength cat ' s eye reflector is combined by convex lens and a concave mirror, and is as a chamber mirror of laser instrument, simultaneously also bonding as target mirror and target object;
Concave output mirror; Be positioned at the axial side of said laser gain pipe, as another chamber mirror of laser instrument, it is towards the inside surface plating 1152nm wavelength reflectance coating of said laser gain pipe; Outside surface plates 1152nm wavelength anti-reflection film, exports the crossed polarized light of above-mentioned two frequencies;
Precision micro-displacement sensor piezoelectric ceramics PZT is adhered to said concave output mirror lower end, makes this concave output mirror do nanoscale along optical axis direction and moves;
Polarization spectroscope is positioned at the concave output mirror outside, separates two bundle crossed polarized lights from said concave output mirror output;
Two photodetectors receive the crossed polarized light of the two bundle different frequencies that said polarization spectroscope separates;
Signal processing circuit, input end links to each other with the signal output of photodetector, accomplishes signal processing function and shows displacement, sees control signal off and drives PZT through high-voltage amplifier.
The invention is characterized in that it is a He-Ne half outside gas laser that is operated in the 1152nm wavelength, comprises:
Laser gain pipe, in fill the He-Ne mixed gas;
Be installed in the anti-reflection window of 1152nm wavelength of said laser gain pipe one side along optical axis direction, the periphery of the anti-reflection window of this wavelength is equipped with afterburning ring, constitutes a stress birefringence element, becomes single-frequency laser the double-frequency laser with two orthogonal polarization orientation;
1152nm wavelength cat ' s eye reflector is combined by convex lens and a concave mirror, and is as a chamber mirror of said He-Ne half outside gas laser, simultaneously also bonding as target mirror and target object;
Precision micro-displacement sensor piezoelectric ceramics PZT is adhered to said cat ' s eye reflector lower end, makes this cat ' s eye reflector do nanoscale along optical axis direction and moves;
Concave output mirror; Be positioned at the side that said laser gain pipe axially is different from anti-reflection window; Another chamber mirror as said He-Ne half outside gas laser is attached on the said laser gain pipe; It is towards the inside surface plating 1152nm wavelength reflectance coating of this laser gain pipe, and outside surface plates 1152nm wavelength anti-reflection film, exports the crossed polarized light of above-mentioned two frequencies;
Polarization spectroscope is positioned at the said concave output mirror outside, separates two bundle crossed polarized lights from this concave output mirror output;
Two photodetectors receive the crossed polarized light of the two bundle different frequencies that said polarization spectroscope separates;
Signal processing circuit, input end links to each other with the signal output of said two photodetectors, accomplishes signal processing function and shows displacement, sees control signal off and drives said precision micro-displacement sensor piezoelectric ceramics PZT through high-voltage amplifier.
1152nm wavelength helium neon laser nano of the present invention is surveyed chi, and its characteristic also is:
Optical element in all light paths, the centre wavelength of plated film are 1152nm.
1152nm wavelength helium neon laser nano of the present invention is surveyed chi, and its characteristic also is:
Said cat ' s eye reflector and target to be measured are bonding, separate with said laser gain pipe.
The present invention is on the basis of patent " nano laser is surveyed chi and realized the divided method of nano measurement "; Replace the 632.8nm wavelength helium neon laser as the core of laser with the 1152nm wavelength helium neon laser from displacement transducer; Make and keep under the constant condition of resolution; Range is extended to more than the 100mm, and utilizes the high-gain of 1152nm wavelength helium neon laser, realize non-cpntact measurement.
Description of drawings
Fig. 1: 1152nm wavelength helium neon laser and 632.8nm wavelength helium neon laser chamber length and longitudinal mode spacing relation are relatively.
Fig. 2: the 1152nm wavelength helium neon laser nano is surveyed one of embodiment of chi: full outer-cavity structure.
Fig. 3: the 1152nm wavelength helium neon laser nano is surveyed two: half outer-cavity structures of the embodiment of chi.
Embodiment
Technical scheme of the present invention is based on a general knowledge of Principles of Laser: long λ/2 that change, chamber, corresponding laser frequency changes a longitudinal mode spacing.Utilize this self calibration characteristic, for the displacement employing step-by-step counting of an integer λ/2, not enough λ/2 displacements adopt the mode of PZT segmentation, carry out wide range and high resolving power and measure.ZL200410088819.4 is said like patent, is the Nano-meter Measurement Ruler of core with the 632.8nm wavelength helium neon laser, and limit of range is at 50mm.Its basic reason is to adopt this technical scheme to require laser works at the single longitudinal mode state, and the chamber length that promptly requires laser instrument is in certain limit.If use the 1152nm wavelength helium neon laser to replace former 632.8nm wavelength helium neon laser as Nano-meter Measurement Ruler, then can make the single longitudinal mode that keeps output laser under the long chamber elongate member, promptly the long range of adjustment in chamber increases greatly.Its ultimate principle is:
At standing-wave laser, the long frequency in longitudinal mode spacing and chamber does
Δ＝c/2L(1)
Δ is a longitudinal mode spacing in the formula, and c is the light velocity, and L is that the chamber is long.When longitudinal mode spacing during more than or equal to the bright dipping bandwidth; Laser works is at the single longitudinal mode state; But the Circuits System operate as normal, otherwise laser works is at many longitudinal modes state, though adopt the processing of circuit method of floating threshold; Can guarantee the operate as normal of Circuits System, be more or less the same but precondition is longitudinal mode spacing and bright dipping bandwidth.This is the long change scope in chamber of the Nano-meter Measurement Ruler of core, i.e. range fundamentally having limited the 632.8nm wavelength helium neon laser just.
Helium-neon laser be with Doppler widen be the master comprehensively widen gas laser; The line width that its 632.8nm spectral line is corresponding is about 1500MHz; Through regulating the loss of laser instrument; Scalable bright dipping bandwidth is to about 800MHz, and when then length was for 150mm to 190mm in the chamber, laser works was single longitudinal mode state (as shown in Figure 1).
The helium-neon laser line width does
In the formula, Δ ν
DBe line width, λ is a wavelength, k
bBe Boltzmann constant, T is an absolute temperature, and m is an atomic mass.Can get Δ ν by following formula
DBe inversely proportional to λ, explain and use the 1152nm wavelength helium neon laser to have littler line width and bright dipping bandwidth, can be in the chamber guarantee the single longitudinal mode running of laser instrument when mirror moves in a big way than former 632.8nm wavelength helium neon laser.The line width that helium-neon laser 1152nm spectral line is corresponding is about 800MHz, and through regulating the loss of laser instrument, scalable bright dipping bandwidth is to about 600MHz, and when then length was for 150mm to 250mm in the chamber, laser works was single longitudinal mode state (as shown in Figure 1).So with the 1152nm wavelength helium neon laser is the moving range that the Nano-meter Measurement Ruler of core can realize chamber mirror 100mm.In conjunction with floating threshold processing of circuit system, can reach the above range of 100mm.
632.8nm wavelength helium neon laser gain is less, so inner chamber can not be exposed in the air, otherwise can because of loss is too big can not bright dipping.Under this condition, the chamber mirror can only move in a seal bootr, contacts with target to be measured through measuring staff, can't realize the non-cpntact measurement that laser gain pipe separates with the chamber mirror.This just requires to adopt the measuring staff structure, and the linearity that will realize so keeping higher on a large scale when moving requires too high to avoid the laser cavity off resonance to machining.Using the 1152nm wavelength helium neon laser to replace former 632.8nm wavelength helium neon laser is to have bigger gain as another advantage of Nano-meter Measurement Ruler core, and the preventing mismatching ability is strong, can realize non-cpntact measurement.Its ultimate principle is:
Helium-neon laser is a four-level system, can know that by Principles of Laser gain coefficient does
In the formula, Δ n is counter-rotating population density, and υ is an atomic motion speed, A
21Be spontaneous radiation probability, ν
0Be centre frequency, g (ν, ν
0) for comprehensively widening linear function.For widening with Doppler is master's helium-neon laser, comprehensively widens linear function and can widen the linear function replacement with Doppler, as ν=ν
0The time, have maximal value to do
Simultaneous formula (3), (4)
Get the cube λ of gain coefficient G and wavelength by formula (5)
3Be directly proportional.Then the gain of 1152nm wavelength helium neon laser is about 6 times of the gain of 632.8nm wavelength helium neon laser, thereby has strengthened the gain of laser instrument greatly.Like this, when built in laser cavity is exposed in the air, just can keep gain, can realize the non-cpntact measurement that gain tube separates with the target mirror greater than loss.Adopt cat ' s eye reflector as the chamber mirror, can guarantee not off resonance of laser cavity when moving on a large scale.
The embodiment that two kinds of 1152nm wavelength nanometer lasers the present invention being listed below in conjunction with accompanying drawing are surveyed chis is further described.
Instance one structure of the present invention is as shown in Figure 2.4 is the outgoing mirror of 1152nm wavelength helium neon laser, and its reflectivity is 99.5%, and reflectance coating is plated in the right surface of this level crossing, and anti-reflection film is plated in the left surface of this level crossing, is full of the mixed gas of helium and neon in the laser gain pipe 7.5 and 8 is anti-reflection window, and anti-reflection film is all plated on two surfaces.10 is cat ' s eye reflector, be made up of the convex lens of a two sides plating anti-reflection film and the concave mirror of a plating total reflection film, and the spacing between convex lens and the concave mirror is adjustable.Full external cavity helium neon laser of 4,5,7,8 and 10 common formations.After diameter adds an external force 9 on the anti-reflection window 8, because the stress birefrin effect makes laser instrument output two bundle crossed polarized lights: directional light and vertical light.Can adjust the frequency difference between the two bundle crossed polarized lights through the size of control external force.Laser gain pipe is enclosed in the aluminium shell 6.From two polarized lights of outgoing mirror 4 outgoing, after polarization splitting prism 3 beam splitting, incide respectively on first detector 1 and second detector 2.The light signal that electronic box 11 receives two detectors converts into to be handled behind the electric signal and shows, and can see control signal off and drive PZT 13 through high-voltage amplifier 12.Outgoing mirror 4 lower end adhesions one micrometric displacement piezoelectric sensor PZT 13 can do the nanoscale motion.
During measurement, the right side of cat ' s eye reflector 10 is bonded on the target to be measured.When target to be measured moves; The chamber personal attendant's of laser instrument variation; Laser instrument output polarization state of light sexually revises generating period, and promptly four polarization states periodically occur successively: have only directional light output → directional light and vertical light all to export → have only vertical light output → unglazed output.Laser beam is surveyed by first detector 1 and second detector 2, has one of four states to occur successively accordingly: have only 1 to be illuminated → 1 and 2 be illuminated simultaneously → have only and 2 be illuminated → 1 and 2 be not illuminated.The change of each state means that laser cavity length has changed the displacement of λ/8, and the sequencing that one of four states occurs can be judged the direction of displacement.According to " the corresponding longitudinal mode spacing of the change of the long half-wavelength in chamber " in the Principles of Laser, experience 4 states so after, the long change amount in chamber is λ/2.When displacement stops to change, judge whether current shift value is the integral multiple of λ/2, if not then according to the voltage on the sense of displacement plus-minus PZT, slight push chamber mirror, it is long to change the chamber, is the integral multiple of λ/2 up to making displacement.The change amount of recording voltage through calculating linear compensation, just can obtain the precise displacement amount of not enough λ/2, thereby instead releases displacement of targets amount to be measured.
Instance two structures of the present invention are as shown in Figure 3.All element numbers are identical with the numbering of counter element among Fig. 2, so locate no longer to repeat to introduce.Be with the difference of instance one: outgoing mirror 4 is attached on the gain tube, outgoing mirror 4, laser gain pipe 7, anti-reflection window 8 and cat ' s eye reflector 10 common formation one and half external cavity helium neon lasers; PZT 13 does not link to each other with concave output mirror 4 but is adhered to cat ' s eye reflector 10 lower ends.Measuring method is identical with instance one.
The 1152nm wavelength helium neon laser nano that the present invention designed is surveyed chi and is had full exocoel and two kinds of structures of half exocoel.Use cat ' s eye reflector bonding as target mirror and target to be measured, when target to be measured when moving axially motion, the corresponding variation takes place in laser instrument output polarization state of light, utilizes the polarization state that successively occurs in proper order, can judge the size and Orientation of displacement of targets to be measured.After the measured target motion stopped, it was long to change the chamber through the voltage on the change PZT, made the integral multiple of the corresponding λ of the long variable quantity in chamber/2, made displacement measurement be traceable to optical wavelength.The 1152nm wavelength helium neon laser nano that the present invention designed is surveyed chi and is reached at range under the situation of 100mm, and resolution can reach 10nm, and realizes the non-cpntact measurement that gain tube and target mirror are separated.
Claims (2)
1.1152nm wavelength helium neon laser nano is surveyed chi, it is characterized in that it is the full outside cavity gas laser of the He-Ne that is operated in the 1152nm wavelength of a non-cpntact measurement, comprises:
Laser gain pipe, in fill the He-Ne mixed gas;
Be installed in the anti-reflection window of 1152nm wavelength of these laser gain pipe both sides respectively along optical axis direction; The periphery of the anti-reflection window of this 1152nm wavelength is equipped with afterburning ring; Constitute a stress birefringence element, become single-frequency laser double-frequency laser with two orthogonal polarization orientation;
1152nm wavelength cat ' s eye reflector is combined by convex lens and a concave mirror, and is as a chamber mirror of laser instrument, simultaneously also bonding as target mirror and target object;
Concave output mirror; Be positioned at the axial side of said laser gain pipe, as another chamber mirror of laser instrument, it is towards the inside surface plating 1152nm wavelength reflectance coating of said laser gain pipe; Outside surface plates 1152nm wavelength anti-reflection film, exports the crossed polarized light of above-mentioned two frequencies;
Precision micro-displacement sensor piezoelectric ceramics PZT is adhered to said concave output mirror lower end, makes this concave output mirror do nanoscale along optical axis direction and moves;
Polarization spectroscope is positioned at the concave output mirror outside, separates two bundle crossed polarized lights from said concave output mirror output;
Two photodetectors receive the crossed polarized light of the two bundle different frequencies that said polarization spectroscope separates;
Signal processing circuit, input end links to each other with the signal output of photodetector, accomplishes signal processing function and shows displacement, sees control signal off and drives PZT through high-voltage amplifier;
The gain coefficient G of the full outside cavity gas laser of described He-Ne does
Wherein, Δ n is counter-rotating population density, and υ is an atomic motion speed, and c is the light velocity, A
21Be the spontaneous radiation probability, m is an atomic mass, k
bBe Boltzmann constant, T is an absolute temperature, and λ is a wavelength, gets the cube λ of gain coefficient G and wavelength
3Be directly proportional.
2.1152nm wavelength helium neon laser nano is surveyed chi, it is characterized in that, it be a non-cpntact measurement be operated in 1152nm wavelength He-Ne half outside gas laser, comprise:
Laser gain pipe, in fill the He-Ne mixed gas;
Be installed in the anti-reflection window of 1152nm wavelength of said laser gain pipe one side along optical axis direction, the periphery of the anti-reflection window of this wavelength is equipped with afterburning ring, constitutes a stress birefringence element, becomes single-frequency laser the double-frequency laser with two orthogonal polarization orientation;
1152nm wavelength cat ' s eye reflector is combined by convex lens and a concave mirror, and is as a chamber mirror of said He-Ne half outside gas laser, simultaneously also bonding as target mirror and target object;
Precision micro-displacement sensor piezoelectric ceramics PZT is adhered to said cat ' s eye reflector lower end, makes this cat ' s eye reflector do nanoscale along optical axis direction and moves;
Concave output mirror; Be positioned at the side that said laser gain pipe axially is different from anti-reflection window; Another chamber mirror as said He-Ne half outside gas laser is attached on the said laser gain pipe; It is towards the inside surface plating 1152nm wavelength reflectance coating of this laser gain pipe, and outside surface plates 1152nm wavelength anti-reflection film, exports the crossed polarized light of above-mentioned two frequencies;
Polarization spectroscope is positioned at the said concave output mirror outside, separates two bundle crossed polarized lights from this concave output mirror output;
Two photodetectors receive the crossed polarized light of the two bundle different frequencies that said polarization spectroscope separates;
Signal processing circuit, input end links to each other with the signal output of said two photodetectors, accomplishes signal processing function and shows displacement, sees control signal off and drives said precision micro-displacement sensor piezoelectric ceramics PZT through high-voltage amplifier;
The gain coefficient G of described He-Ne half outside gas laser does
Wherein, Δ n is counter-rotating population density, and υ is an atomic motion speed, A
21Be the spontaneous radiation probability, c is the light velocity, and m is an atomic mass, k
bBe Boltzmann constant, T is an absolute temperature, and λ is a wavelength, gets the cube λ of gain coefficient G and wavelength
3Be directly proportional.
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| CN2009100763083A CN101464139B (en) | 2009-01-09 | 2009-01-09 | 1152nm wavelength helium neon laser nano-measuring tape |
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| CN2009100763083A CN101464139B (en) | 2009-01-09 | 2009-01-09 | 1152nm wavelength helium neon laser nano-measuring tape |
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| CN101464139B true CN101464139B (en) | 2012-05-23 |
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Families Citing this family (5)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN102506685B (en) * | 2011-10-26 | 2014-03-05 | 清华大学 | Displacement measurement method based on piezoelectric ceramic open-loop modulation |
| CN103464959A (en) * | 2013-09-11 | 2013-12-25 | 奇昊汽车系统（苏州）有限公司 | Cross car beam (CCB) welding device with protection function |
| CN106500601A (en) * | 2016-10-13 | 2017-03-15 | 南通大学 | Helium neon laser nano surveys ruler system |
| CN106500602A (en) * | 2016-10-13 | 2017-03-15 | 南通大学 | Helium neon laser nano surveys ruler system |
| CN111174708B (en) * | 2020-01-13 | 2021-03-30 | 山西大学 | Method and device for measuring cavity length of micro-optical resonant cavity |
Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1103161A (en) * | 1993-11-26 | 1995-05-31 | 清华大学 | High precision measuring method and device for laser cavity change displacement and refractive index |
| CN1233093A (en) * | 1999-04-02 | 1999-10-27 | 清华大学 | Displacement self-sensing helium-neon laser system and its embodiment method |
| CN1603739A (en) * | 2004-11-05 | 2005-04-06 | 清华大学 | Nano laser measuring rule and subdivision method for nano measurement realization |
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Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1103161A (en) * | 1993-11-26 | 1995-05-31 | 清华大学 | High precision measuring method and device for laser cavity change displacement and refractive index |
| CN1233093A (en) * | 1999-04-02 | 1999-10-27 | 清华大学 | Displacement self-sensing helium-neon laser system and its embodiment method |
| CN1603739A (en) * | 2004-11-05 | 2005-04-06 | 清华大学 | Nano laser measuring rule and subdivision method for nano measurement realization |
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