CN103115571B - Displacement measurement system - Google Patents
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- CN103115571B CN103115571B CN201310020741.1A CN201310020741A CN103115571B CN 103115571 B CN103115571 B CN 103115571B CN 201310020741 A CN201310020741 A CN 201310020741A CN 103115571 B CN103115571 B CN 103115571B
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Abstract
The invention provides a kind of displacement measurement system, mainly comprise: a laser instrument, in order to export double-frequency laser; One data acquisition and processing unit, in order to receive the interference laser of laser instrument output and to carry out data processing; Wherein, comprise a feedback unit further, described feedback unit comprise one first catoptron and the second catoptron relatively and interval arrange, described first catoptron has a first surface directly to receive incident laser, and described first surface has multiple the first groove extend side by side in the same direction; Described second catoptron has and the second surface faced by described first surface, and described second surface comprises multiple the second groove extended in the same direction; One the 3rd catoptron, the laser that described laser instrument exports after multiple reflections, is incident to described 3rd catoptron between described multiple first groove and multiple second groove, after described 3rd catoptron reflection, form laser feedback along in original optical path return laser light device.
Description
Technical field
The invention belongs to displacement measuring technology field, especially about a kind of nano-grade displacement measuring system based on right-angle prism feedback.
Background technology
Nano measurement is the basis of nano science development, and nano science is mainly studied, to be found and processing structure size is less than the material of 100 nanometers, device and system, to obtain required function and performance, and be used widely in fields such as material, chemistry, biology, the energy and medical and health.Along with the arrival of nanometer era, the demand that the product of nanoscale detects is increased day by day, also higher standard is proposed to nano measurement technology simultaneously.Nano measurement needs to reach nano level resolution in millimetre-sized measurement range, needs the requirement considering the aspects such as environmental baseline, system complexity and traceability simultaneously.
Nano measurement technology is according to the standard of range, resolution and uncertainty of measurement, two large classes can be divided into: a class is mentioned laser interferometer, be characterized in that range is large, can reach tens meters, but the divided method such as displacement electronics phase demodulation being less than half optical wavelength is realized; Another kind of is beat method Fabry-Perot-type (Fabry-Perot, F-P) interferometer technique, X ray interferometer technique, optics+X ray interferometer technique, frequency measurement technology and frequency comb technology etc., their feature is that resolution and uncertainty of measurement are low, can reach sub-nanometer even micromicron magnitude.But mentioned laser interferometer is due to the impact of the nonlinearity errons such as electronic noise, the displacement measurement within half-wavelength is also unreliable, is therefore difficult to meet high-resolution requirement.And the range of beat Fabry-Perot interferometer technology etc. is little, generally in micron dimension, limit its range of application.
Displacement measurement method based on laser feedback has that structure is simple, autocollimation and the high advantage of cost performance.But, traditional laser feedback that utilizes is measured in the measurement mechanism of displacement, owing to adopting uncollimated external cavity feedback, the feedback order of laser beam in feedback exocoel and resolution can not directly obtain, but after needing interferometer to demarcate, just can know the resolution of this device, when realizing nano level displacement measurement resolution, the self-calibration of resolution cannot be realized.
Summary of the invention
In sum, necessaryly provide a kind of and there is nanometer resolution and directly can obtain the displacement measurement system of resolution.
A kind of displacement measurement system, mainly comprises: a laser instrument, in order to export double-frequency laser; One data acquisition and processing unit, in order to receive the interference laser of laser instrument output and to carry out data processing; Wherein, comprise a feedback unit further, described feedback unit comprises: one first catoptron, described first catoptron has a first surface directly to receive incident laser, described first surface has multiple the first groove extended along first direction, and each first groove comprises one first vertical side and one second side; One second catoptron and interval relative with described first catoptron is arranged, described second catoptron has and the second surface faced by described first surface, described second surface comprises multiple the second groove extended along first direction, and each second groove comprises one the 3rd vertical side and one the 4th side; And one the 3rd catoptron be arranged on described first catoptron side, and in the face of described second catoptron setting, the laser that laser instrument exports is directly transmitted to described first catoptron, after multiple reflections between multiple first groove of described first catoptron and multiple second grooves of the second catoptron, be incident to described 3rd catoptron, after described 3rd catoptron reflection, form laser feedback along in original optical path return laser light device.
A kind of displacement measurement system, mainly comprises: a laser instrument, in order to export the double-frequency laser along Z-direction; One data acquisition and processing unit, in order to receive the interference laser of laser instrument output and to carry out data processing; Wherein, comprise a feedback unit further, described feedback unit comprises one first catoptron, the second catoptron and one the 3rd catoptron, described first catoptron and interval relative with described second catoptron is arranged, described first catoptron has a first surface, and described first surface comprises an incidence zone, the first echo area, the first boot section, the second boot section; Described incidence zone has multiple the 3rd groove extended in X direction; Described first echo area has multiple the 4th groove extended in X direction, and described 4th groove and described 3rd groove are arranged side by side; Described first boot section, the first echo area and described second boot section set gradually along Y-direction, and described first boot section has multiple the 5th groove extended along Y-direction; Described second boot section has multiple the 6th groove extended along Y-direction, and described 6th groove and described 5th groove interlock corresponding setting; Described second catoptron has a second surface and described first surface in the face of arranging, and described second surface has multiple the second groove extended in X direction; Wherein, the direction of laser instrument Output of laser is Z-direction, and the direction vertical with Z-direction is orthogonal X-direction and Y-direction; The laser of laser instrument incidence is directly transmitted to the 3rd groove of described incidence zone, and reflex to described 4th groove through the second groove, one the 5th groove is incident to after multiple reflections between described 4th groove and described second groove, the 4th groove is again incident to after the 5th groove reflection, and described 6th groove is incident to after the reflection of the 4th groove and the second groove, after one the 6th groove reflection, be incident to described second groove; Described 3rd catoptron reflection from the laser of the second groove incidence described in described second catoptron, and makes described laser form laser feedback along in original optical path return laser light device after described 3rd catoptron reflection.
Compared with prior art, displacement measurement system provided by the invention, by arranging the second catoptron and the first catoptron forms feedback unit in feedback unit, utilize the weak feedback effect of substance high-order that laser comes and goes between the first catoptron and the second catoptron, on the one hand there is high-order frequency-doubled effect, nano level displacement measurement resolution can be reached; On the other hand, the resolution of described displacement measurement system can be counted according to the reflected light in feedback unit simultaneously and be obtained, and demarcates without the need to other devices, because the method is more simple, therefore has broad application prospects.
Accompanying drawing explanation
Fig. 1 is the structural representation of the displacement measurement system that first embodiment of the invention provides.
Fig. 2 is the structural representation of feedback unit in displacement measurement system described in Fig. 1.
Fig. 3 is the structural representation of the first catoptron and the second catoptron in feedback unit shown in Fig. 2.
Fig. 4 is the structural representation of the second catoptron in feedback unit shown in Fig. 2.
Fig. 5 is the index path in feedback unit.
The structural representation of the displacement measurement system that Fig. 6 provides for second embodiment of the invention.
Fig. 7 is the structural representation of feedback unit in displacement measurement system shown in Fig. 6.
Fig. 8 is the structural representation of the first catoptron in feedback unit shown in Fig. 7.
Fig. 9 is for the first catoptron shown in Fig. 8 is along the structural representation in Y-Z face.
Figure 10 is for the first catoptron shown in Fig. 8 is along the structural representation in X-Z face.
Figure 11 is for the first catoptron shown in Fig. 8 is along the structural representation in X-Z face.
Figure 12 is the feedback intensity modulation curve of traditional bit shift measurement system.
The feedback intensity modulation curve of the displacement measurement system that Figure 13 provides for second embodiment of the invention.
Main element symbol description
| First catoptron | 1 |
| Second catoptron | 2 |
| Resonant reflec-tors in second | 3 |
| Birefringence element | 4 |
| Anti-reflection window | 5 |
| Gain tube | 6 |
| Resonant reflec-tors in first | 7 |
| Amici prism | 8 |
| First photodetector | 9 |
| Second photodetector | 10 |
| Filter amplification circuit | 11 |
| Signal processing unit | 12 |
| Display device | 13 |
| Laser instrument | 20 |
| Feedback unit | 30 |
| Data acquisition and processing unit | 40 |
| First surface | 101 |
| Incidence zone | 102 |
| First echo area | 103 |
| First boot section | 104 |
| Second boot section | 105 |
| 3rd catoptron | 1013 |
| First fin | 1012 |
| Second surface | 201 |
| Second fin | 2012 |
| First groove | 1011 |
| First side | 1011a、1021a、1031a、1041a、1051a |
| Second side | 1011b、1021b、1031b、1041b、1051b |
| Second groove | 2011 |
| 3rd side | 2011a |
| 4th side | 2011b |
Following specific embodiment will further illustrate the present invention in conjunction with above-mentioned accompanying drawing.
Embodiment
Displacement measurement system provided by the invention and measuring method thereof is described in detail below with reference to accompanying drawing.
Refer to Fig. 1, first embodiment of the invention provides a kind of displacement measurement system, and described displacement measurement system comprises laser instrument 20, feedback unit 30 and a data acquisition and processing unit 40.The laser exported from described laser instrument 20 enters described feedback unit 30, returns described laser instrument 20, and enter data acquisition and processing unit 40 after feedback unit 30 feedback reflection.
Described laser instrument 20, for exporting double-frequency laser; Gas laser, solid state laser or semiconductor laser etc. can be selected.In the present embodiment, described laser instrument 20 is a helium-neon laser.Described laser instrument 20 comprises a shell 15, and to be arranged in one first in shell 15 resonant reflec-tors 3 in resonant reflec-tors 7, gain tube 6, anti-reflection window 5, birefringence element 4 and one second.Described shell 15 contributes to the temperature and the thermal equilibrium that keep laser instrument 20 inside.Described gain tube 6 is fixed in described shell 15 by a bracing frame 14.Be appreciated that support frame as described above 14, shell 15 is an alternate configurations.In resonant reflec-tors 7 in described first, gain tube 6, anti-reflection window 5, birefringence element 4 and second, resonant reflec-tors 3 is along the axis coaxial setting successively of described laser instrument 20 Output of laser, and forms the inner chamber of laser instrument.Described birefringence element 4 is for generation of frequency splitting, and make described laser instrument 20 export double-frequency laser, the material of described birefringence element 4 can be quartz crystal, bilingual stone etc., also can produce the material of frequency splitting for other.Described birefringence element 4 in described anti-reflection window 5 and described second between resonant reflec-tors 3, and and in described anti-reflection window 5 and described second resonant reflec-tors 3 interval arrange.Described birefringence element 4 has two relative planes on Output of laser axis direction, and described two planes all plate anti-reflection film.The chamber of the inner chamber of described laser instrument 20 is long can be 180mm ~ 200mm.
Described data acquisition and processing unit 40 in order to receive the interference laser exported from resonant reflec-tors 7 in described laser instrument 20 first, and carry out data processing and calculate umber of pulse.Described data acquisition and processing unit 40 comprise Amici prism 8, first photodetector 9, second photodetector 10, filter amplification circuit 11, signal processing unit 12 and a display device 13.Described Amici prism 8 resonant reflec-tors 7 in first of described laser instrument 20 is arranged, and to receive from laser instrument 20 laser that in first, resonant reflec-tors 7 exports, and the laser of output is divided into o light, the e light component that two-way has phasic difference in space.Described first photodetector 9, second photodetector 10 in order to detect the o light and e light component that are exported by Amici prism 8 respectively, and is converted into two path signal.Described filter amplification circuit 11 is electrically connected with described first photodetector 9 and the second photodetector 10, and carries out current/voltage-converted, amplification and filtering process to two path signal.Described signal processing unit 12 processes for the two path signal exported filter amplification circuit 11 and realizes counting, the umber of pulse N produced during to calculate change in optical path length, and according to the direction of motion of the relatively advanced or delayed judgement testee in the position of two path signal.Further, be electrically connected with described signal processing unit 12 by described display device 13, show for number of pulses N.Be appreciated that described display device 13 is only an optional structure, described umber of pulse N also obtains by other counting elements.
See also Fig. 2 and Fig. 3, described feedback unit 30 comprises one first catoptron 1, second catoptron 2 and one the 3rd catoptron 1013, described second catoptron 2 and interval relative with described first catoptron 1 is arranged, its minimum spacing d can be more than or equal to 1 millimeter and be less than or equal to 1000 millimeters, as 2 millimeters, 5 millimeters, 10 millimeters, 20 millimeters etc.Described feedback unit 30 forms the FP feedback exocoel of described laser instrument 20.The material of described first catoptron 1 and the second catoptron 2 can be glass, also can be other transparent solid materials.Described first catoptron 1 has a first surface 101 towards described laser instrument 20, makes Output of laser can be directly transmitted to described first surface 101.Described second catoptron 2 has a second surface 201 and is oppositely arranged with described first surface 101, second surface 201 is incident to after being incident to the laser reflection of first surface 101, and after the reflection of second surface 201, return first surface 101 again, by that analogy.After multiple reflections, described laser reflexes to the 3rd catoptron 1013 from described second surface 201, after the 3rd catoptron 1013 reflects, form laser feedback along in original optical path return laser light device 20.
The first surface 101 of described first catoptron 1 comprises multiple first reflector elements be disposed adjacent, the surface of described second surface 201 comprises multiple second reflector elements be disposed adjacent, the laser that laser instrument 20 exports is directly incident on described first reflector element, and through reflection back reflection to the second reflector element of the first reflector element; And then reflex to the first reflector element through the second reflector element, by that analogy, the laser that described laser instrument exports is at the first reflector element and the second reflector element multiple reflections.Finally, the laser through the second reflector element reflection incides described 3rd catoptron 1013, along in original optical path return laser light device 20 after the reflection of the 3rd catoptron 1013, forms laser feedback.Concrete, each first reflector element described can comprise one first groove 1011, and each second reflector element described comprises one second groove 2011.The bearing of trend of described first groove 1011 and the second groove 2011 is all identical.Each first groove 1011 comprises one first side 1011a and one second side 1011b, and each second groove 2011 comprises one the 3rd side 2011a and the 4th side 2011b.The laser that laser instrument 20 exports is directly incident on one first side 1011a, then reflexes to the second adjacent side 1011b; Reflex to the 3rd side 2011a through the second side 1011b, then reflex to the 4th side 2011b; After the 4th side 2011b reflects, then reflex to the first side 1011a of next the first reflector element, the like, laser is past interflection between the first reflector element and the second reflector element.Finally, the laser reflected through the 4th side 2011b incides described 3rd catoptron 1013, after the 3rd catoptron 1013 reflects, along in original optical path return laser light device 20, forms laser feedback.
Refer to Fig. 3, the Laser output direction of definition laser instrument 20 is Z-direction, and the direction vertical with Z-direction is defined as X-direction, Y-direction respectively, and X, Y, Z are mutually vertical.Described multiple first groove 1011 extends in X direction, and namely the bearing of trend of described first groove 1011 is perpendicular to the direction of described laser instrument 20 Output of laser, and described multiple first groove 1011 is arranged side by side along Y-direction.Described first side 1011a and the second side 1011b is a plane, and mutually vertically forms described first groove 1011.Described first groove 1011 can be V-arrangement at the xsect of X-direction, can be also other shapes, arranges as long as ensure that described first side 1011a is vertical with described second side 1011b.Described first side 1011a and the second side 1011b is arranged alternately in the Y direction, and form one first fin 1012 between two adjacent the first grooves 1011, the drift angle of described first fin 1012 is right angle.Described first fin 1012 can be the absolute construction being arranged at a matrix (not shown), also can form an integrative-structure with described matrix.In the present embodiment, each first fin 1012 described combines for two right-angle prisms being arranged at a matrix surface, and right-angle prism xsect is in their extension direction isosceles triangle.The first side 1011a and the second side 1011b that inclined-plane forms described first groove 1011 are set in described right-angle prism in opposite directions.The degree of depth and the width of described multiple first groove 1011 are all identical.Described " width " refer to each first groove 1011 described in the Y direction across ultimate range.In the present embodiment, the width of described first groove 1011 is 23 millimeters.The laser that laser instrument 20 exports is directly transmitted to described first side 1011a, and is incident to described second side 1011b after the first side 1011a reflects, and the normal of described laser instrument 20 Output of laser and described first side 1011a is 45 degree.
See also Fig. 4, described second catoptron 2 has a second surface 201 relative with described first surface 101, described second surface 201 has multiple second grooves 2011 extend side by side in the same direction equally, the bearing of trend of described second groove 2011 is identical with the bearing of trend of described first groove 1011, and described multiple second groove 2011 is same along Y-direction side by side.Form one second fin 2012 between the second adjacent groove 2011, and the drift angle of described second fin 2012 is right angle.The structure of described second groove 2011 as shape, the degree of depth and width all with as described in the first groove 1011 identical.Described multiple second groove 2011 and described multiple first groove 1011 is staggered correspondingly arranges.Described staggered correspondence arranges and refers to that described second groove 2011 and described first fin 1012 are in the face of arranging, and described second fin 2012 and described first groove 1011 are in the face of arranging.Described 3rd side 2011a and the 4th side 2011b intersects vertically and forms described second groove 2011, and described second groove 2011 xsect is in the X direction V-arrangement.One second fin 2012 is formed between two adjacent the second grooves 2011.Concrete, in z-direction, described 3rd side 2011a with described second side 1011b parallel interval and in the face of arranging, described 4th side 2011b parallel with described first side 1011a and faced by arrange.
Described 3rd catoptron 1013 in order to be reflected into the laser being incident upon the 3rd catoptron 1013, and makes incident laser return in described laser instrument 20 along the former road of input path.Laser instrument 20 Output of laser, after described first catoptron 1 and the second catoptron 2 multiple reflections, is incident to described 3rd catoptron 1013, and reflects Hou Yanyuan road through the 3rd catoptron 1013 and return in described laser instrument 20, forms laser feedback.In the present embodiment, described 3rd catoptron 1013 is a plane, is arranged at the first surface 101 of described first catoptron 1, and perpendicular to the direction of described laser instrument 20 Output of laser.Further, on described 3rd catoptron 1013 surface, the input path of described laser can overlap with reflected light path.Multiple first grooves 1011 side by side described in described 3rd catoptron 1013 is arranged at, along the end of Y-direction, are connected with the second side 1011b of described second groove 1011.Further, the described 3rd four side 2011b of catoptron 1013 along the second groove 2011 of Y-direction end in described second catoptron 2 is arranged, and to reflect the laser from the 4th side 2011b incidence, makes it along original optical path return laser light device 20.Be appreciated that, described 3rd catoptron 1013 also can be the reflecting element arranged separately, as catoptron, prism of corner cube etc., can be integrated with described first catoptron 1, also can arrange respectively, as long as ensure that laser that described laser instrument 20 exports is after the 3rd catoptron 1013 reflects, and can be reflected back described laser instrument 20 and form feedback.
See also Fig. 5, the described first side 1011a that laser instrument 20 Output of laser is directly incident sorts as a
1, the second side 1011b directly incident after its refraction sorts as b
1; In the Y direction with described b
1the first adjacent side 1011a sorts as a
2, with a
2the second adjacent side 1011b sorts as b
2, by that analogy.Then described first side 1011a and described second side 1011b along Y-direction according to a
1, b
1, a
2, b
2a
n, b
nmode arrange.Described b
nindividual second side 1011b is connected with described 3rd catoptron 1013.Meanwhile, by laser instrument 20 Output of laser after the first catoptron 1 reflects, described first incident the 3rd side 2011a sorts as c
1, the 4th side 2011b incident after superrefraction sorts as d
1; In the Y direction with institute c
1the 3rd adjacent side 2011a sorts as c
2, with c
2the 4th adjacent side 2011b sorts as d
2, by that analogy.Namely described 3rd side 2011a and described 4th side 2011b along Y-direction according to c
1, d
1, c
2, d
2c
n, d
nmode arrange.Described d
nindividual 4th side 2011b and described 3rd catoptron 1013 are in the face of arranging, through d
nafter laser after individual 4th side 2011b reflects is incident to described 3rd catoptron 1013, after the reflection of the 3rd catoptron 1013, be back to described d along original optical path
n.In the present embodiment, laser is through d
nafter reflection, be incident to described 3rd catoptron 1013 along the direction perpendicular to the 3rd catoptron 1013, and after the 3rd catoptron 1013 reflects, return along original optical path.
Concrete, the laser that laser instrument 20 exports is incident to a
1, and through a
1reflex to b
1, b
1by laser reflection to c
1, c
1reflex to d again
1, through d
1reflection back reflection is to a
2, the like.That is, laser is according to a
1-b
1-c
1-d
1-a
2-...-a
n-b
n-c
n-d
nmode reflect successively, and laser is through d
nafter reflection, be directly transmitted to described 3rd catoptron 1013, and after the 3rd catoptron 1013 reflects, reflex to d
n, then by being back in laser instrument 20 along original optical path, form feedback.
The principle of described displacement measurement system is as follows.Described first catoptron 1 is fixed on object under test one surface.Be appreciated that described first catoptron 1 can omit when namely described object under test surface itself has a plane of reflection.Divided two crossed polarized light o light and the e light of generation by birefringence element 4, when light feedback, light field can be divided into two parts.Reflector space is the inner chamber propagation field of light beam after laser instrument 20 inner chamber comes and goes one week, and regional transmission is the propagation field that light beam comes and goes that in feedback unit 30 n week (i.e. feedback order) Hou Zaiyanyuan road turns back to laser instrument 20 inner chamber.Due to the multiple reflections through the first catoptron 1 and the second catoptron 2, therefore the laser attenuation of laser instrument 20 output is larger, so the feedback light intensity finally turned back in laser cavity is more weak, so just can realize substance, high-order, weak feedback effect when not adding attenuator.Just can know feedback order according to coming and going number of times in laser is in feedback unit 30, thus obtain the resolution of feedback unit 30, and not need other instrument to demarcate, and there is higher resolution.
Refer to Fig. 6 and Fig. 7, second embodiment of the invention provides a kind of displacement measurement system, and described displacement measurement system comprises laser instrument 20, feedback unit 30 and a data acquisition and processing unit 40.The laser exported from described laser instrument 20 enters described feedback unit 30, returns described laser instrument 20, and enter data acquisition and processing unit 40 after feedback unit 30 feedback reflection.Described feedback unit 30 comprises one first catoptron 1 and the second catoptron 2.
The displacement measurement system that second embodiment of the invention provides, substantially identical with the displacement measurement system that the first embodiment provides, its difference is, in the displacement measurement system that described second embodiment provides, described first catoptron 1 comprises multiple reflector space.
See also Fig. 8 to Figure 11, the first surface 101 of described first catoptron 1 is divided into boot section, boot section 104, second, echo area 103, first, incidence zone 102, first 105 and one the 3rd catoptron 1013 according to the travel path of laser.In the X direction, described incidence zone 102 is disposed adjacent with described second boot section 105, and described 3rd catoptron 1013 is arranged at one end away from incidence zone 102, described second boot section 105.In the Y direction, described first echo area 103, boot section 104, first and described second boot section 105 set gradually along Y-direction, and described first boot section 104 and described second boot section 105 are for guiding the translation in X direction in reflection process of described laser.Described first echo area 103 is disposed adjacent with described incidence zone 102 and the second boot section 105 simultaneously; Described first boot section 104 is disposed adjacent with described first echo area 103.The laser of described laser instrument 20 outgoing is directly transmitted to described incidence zone 102, and to the first echo area 103 after the second catoptron 2 reflects, the like, through the first boot section 105, echo area 103, second, boot section 104, first, echo area 103, first, finally enter to inject described 3rd catoptron 1013, and to be back in described laser instrument 20 by original optical path after the 3rd catoptron 1013 reflects and to form feedback.
In the present embodiment, described incidence zone 102 comprises one the 3rd groove 1021 and extends in X direction, each the 3rd groove 1021 described comprises one first side 1021a and one second side 1021b, and described first side 1021a and described second side 1021b intersects vertically and forms described 3rd groove 1021.The length that described 3rd groove 1021 extends in the X direction equals the half of described 3rd groove 1021 width.The laser that described laser instrument 20 exports is directly transmitted to described first side 1021a, and is incident to described second side 1021b after the first side 1021a reflects.Described second side 1021b is parallel with the 3rd side 2011a of described second catoptron 2 and in the face of arranging, laser, after the second side 1021b reflects, is incident to the 3rd side 2011a of described second catoptron 2.The structure of described 3rd groove 1021 is substantially identical with the structure of described first groove 1011.Described 3rd groove 1021 is formed by the right-angle prism of two horizontal positioned in X direction, and the inclined-plane of two right-angle prisms arranges in opposite directions and forms described 3rd groove 1021.The width of described 3rd groove 1021 is 23 millimeters, and development length is 11.5 millimeters.
In the present embodiment, described first echo area 103 comprises multiple the 4th groove 1031 extended in X direction, and described multiple 4th groove 1031 is arranged side by side in the Y direction.Each the 4th groove 1031 described comprises one first side 1031a and one second side 1031b.In described first side 1031a and described incidence zone 102, the second side 1021b of the 3rd groove 1021 intersects vertically.The length that described 4th groove 1031 extends is more than or equal to the length of boot section 105, described incidence zone 102, second in X-direction, thus ensures that described laser can incide described 3rd catoptron 1013.The hierarchy structure of described 4th groove 1031 is identical with described 3rd groove 1021.Described 4th groove 1031 is made up of the right-angle prism that 6 articles be arranged in parallel, and the inclined-plane that adjacent two right-angle prisms are arranged in opposite directions forms described 4th groove 1031, forms 3 the 4th grooves 1031.Described 4th groove 1031 is at the length l of X-direction
2be 115 millimeters, width is 23 millimeters.Second groove 2011 on described 4th groove 1031 and described second catoptron 2 surface is staggered correspondingly to be arranged.The laser of described laser instrument 20 outgoing is after the reflection of incidence zone 102 and the second catoptron 2, be incident to the first side 1031a of described 4th groove 1031, then reflex to the second side 1031b, and reflex to the second catoptron 2 through the second side 1031b, the like.
Described first boot section 104 comprises multiple the 5th groove 1041 extended along Y-direction, and each the 5th groove 1041 described comprises the one first side 1041a and the second side 1041b that intersect vertically.The structure of described 5th groove 1041 is substantially identical with the structure of described 3rd groove 1021, and bearing of trend is mutually vertical.In the X direction, described multiple 5th groove 1041 is arranged side by side, and the total length that described multiple the 5th groove 1041 be arranged side by side extends in the X direction is more than or equal to the development length of described 4th groove 1031, thus ensure that described laser can incide described 3rd catoptron 1013.The laser that described laser instrument 20 exports, through incidence zone 102 and the multiple reflections between the first echo area 103 and the second catoptron 2, enters in the groove 1041 of described first boot section 104 1 5th.Described 3rd groove 1021 is corresponding with one first side 1051a of described 5th groove 1041 in the Y direction to be arranged, namely after reflecting between the 3rd groove 1021 and the second catoptron 2, again after multiple reflections between the 4th groove 1031 and described second catoptron 2, first incide described first side 1051a.The width of each the 5th groove 1041 described equals the twice of described 3rd groove 1021 development length, and described 3rd groove 1021 is corresponding with the first side 1041a of described 5th groove 1041 to be arranged, namely in the X direction, the length that described 3rd groove 1021 extends equals the development length of the first side 1041a, and laser is incident to described first side 1041a after multiple reflections, and then reflex to the second side 1041b through the first side 1041a.Described 5th groove 1041 is made up of the right-angle prism that 10 are arranged along Y-direction, and the inclined-plane of adjacent two right-angle prisms forms described 5th groove 1041, forms 5 the 5th grooves 1041.Each right-angle prism length is in the Y direction 11.5 millimeters.The width forming each the 5th groove 1041 is 23 millimeters, and the length extended in the Y direction is 11.5 millimeters.Be appreciated that the length that the 5th groove 1041 extends in the Y direction is not limited to above act, as long as ensure that length that described 5th groove 1041 extends in the Y direction is more than or equal to the half of the second groove 2011 width described in described second catoptron 2.
Described second boot section 105 comprises multiple 6th grooves 1051 extended along Y-direction, and described multiple 6th groove 1051 is arranged side by side in the X direction.Each the 6th groove 1051 described comprises the one first side 1051a and the second side 1051b that intersect vertically, and in described 6th groove 1051 of described incidence zone 102, described first side 1051a is connected with described incidence zone 102.The structure of described 6th groove 1051 is substantially identical with the structure of described 5th groove 1041 and extend in the same direction, further, described 6th groove 1051 and described 5th groove 1041 is staggered correspondingly arranges, namely the second side 1041b of the first side 1051a and described 5th groove 1041 of described 6th groove 1051 in the Y direction corresponding same X-coordinate arrange; Second side 1051b of described 6th groove 1051 is arranged with the corresponding same X-coordinate of the first side 1041a of described 5th groove 1041.Through described 5th groove 1041 second side 1041b reflect laser behind the first echo area 103 and the second catoptron 2 multiple reflections, be first incident to the first side 1051a of described 6th groove 1041; Through described 6th groove 1051 second side 1051b reflect laser behind the first echo area 103 and the second catoptron 2 multiple reflections, be incident to the first side 1041a of described 5th groove 1041, the like.Described 6th groove 1051 development length is in the Y direction more than or equal to the length that described 3rd groove 1021 extends in X-direction, and the width of described 6th groove 1051 equals the twice of described 3rd groove 1021 development length, thus ensure that the laser exported from laser instrument 20 can be incident to described 6th groove 1051 after multiple reflections.In the present embodiment, described second boot section 105 is made up of the right-angle prism that 8 set gradually in X direction, and the inclined-plane of two adjacent right-angle prisms forms described 6th groove 1051, forms 4 the 6th grooves 1051.
Described 3rd catoptron 1013 for reflecting incident laser, and makes laser return along input path.Described 3rd catoptron 1013 is arranged at described second boot section 105 in the X direction away from one end of described incidence zone 102.Described 3rd catoptron 1013 can be a plane mirror, also can be a prism of corner cube, can form integrative-structure with described first catoptron 1, also can be the reflecting element arranged separately.The laser being incident to the 3rd catoptron 1013, after the 3rd catoptron 1013 reflects, returns along input path.In the present embodiment, described 3rd catoptron 1013 is the level crossing be disposed adjacent with described second boot section 105.Be appreciated that described 3rd catoptron 1013 also can be disposed adjacent with described first boot section 104, as long as ensure that the laser that described laser instrument 20 incides the 3rd catoptron 1013 can return along original optical path.
The principle of described displacement measurement system is as follows.Described first catoptron 1 is fixed on object under test one surface.Be appreciated that described first catoptron 1 can omit when namely described object under test surface itself has a plane of reflection.Divided two crossed polarized light o light and the e light of generation by birefringence element 4, when light feedback, light field can be divided into two parts.Reflector space is the inner chamber propagation field of light beam after laser instrument 20 inner chamber comes and goes one week, and regional transmission is the propagation field that light beam comes and goes that in feedback unit 30 n week (i.e. feedback order) Hou Zaiyanyuan road turns back to laser instrument 20 inner chamber.Inner chamber propagation field superposes with the propagation field turning back to inner chamber after feedback unit 30 comes and goes n week and forms self-mixed interference, and under low light level feedback condition, the output intensity of o light and e light can be expressed as:
（1）
In formula:
with
the output intensity of two crossed polarized lights when being unglazed feedback,
with
the laser feedback factor,
with
coupling coefficient,
with
be the angular frequency of o light and e light, l is the spacing between the first catoptron 1 and the second catoptron 2.When above formula shows there is light feedback, the output intensity of two crossed polarized lights is all modulated, and waveform is similar to cosine curve.Especially, the fringe density of feedback fringe is primarily of feedback order
determine.
The laser that laser instrument 20 exports is advanced along following path in described feedback unit 30.The laser that laser instrument 20 exports is directly transmitted to the first side 1021a of the 3rd groove 1021 in described incidence zone 102, reflexes to the second side 1021b; After the reflection of the second side 1021b, be incident to the 3rd side 2011a of the second groove 2011 in described second catoptron 2, and reflex to the 4th side 2011b;
After the reflection of the 4th side 2011b, described laser is incident to the first side 1031a of the 4th groove 1031 in described first echo area 103, and reflexes to the second side 1031b;
After the reflection of the second side 1031b, described laser is incident to the 3rd side 2011a of the second groove 2011 in described second catoptron 2, and reflex to the 4th side 2011b, then be reflected back the first side 1031a of the 4th groove 1031 in described first echo area 103;
Between the first echo area 103 and the second catoptron 2 after multiple reflections, be incident to the first side 1041a of the 5th groove 1041 described in described first boot section 104, and reflex to the second side 1041b;
After the second side 1041b reflects, described laser is incident to the 4th side 2011b of described second catoptron 2, and reflexes to the 3rd side 2011a;
After the 3rd side 2011a reflects, described laser is incident to the second side 1031b of the 4th groove 1031 described in described first echo area 103, and reflexes to the first side 1031a;
Between the first echo area 103 and the second catoptron 2 after multiple reflections, described laser is incident to the first side 1051a of the 6th groove 1051 described in described second boot section 105, and reflexes to the second side 1051b;
After the second side 1051b reflects, described laser is incident to the 3rd side 2011a of the second groove 2011 in described second catoptron 2, and reflexes to the 4th side 2011b;
After the 4th side 2011b reflects, described laser is incident to the first side 1031a of the 4th groove 1031 described in described first echo area 103, and reflexes to the second side 1031b;
After the reflection of the second side 1031b, described laser is incident to the 3rd side 2011a of the second groove 2011 described in described second catoptron 2, and after reflexing to the 4th side 2011b, then be reflected back described first echo area 103;
Described laser is after the multiple reflections between the first echo area 103 and the second catoptron 2, be incident to described first boot section 104, behind the first boot section 104 with the reflection of described second catoptron 2, once more be reflected back described first echo area 103, and reflexing to described second boot section 105, circulation is carried out successively.
Finally, described laser is after multiple reflections, the laser reflected from the 3rd side 2011a of the second groove 2011 described in described second catoptron 2 is incident to described 3rd catoptron 1013, then through the reflection of the 3rd catoptron 1013, make described laser be back in described laser instrument 20 along input path, form laser feedback.
See also Figure 12 and Figure 13, during measurement, described incidence zone 102 is moved along laser axis direction, and the laser intensity curve that described first photodetector 9, second photodetector 10 obtains as shown in figure 13, for very close high-order frequency multiplication striped, be tens times of the weak feedback of the tradition shown in Figure 12.The optical resolution of described displacement measurement system can be less than 10 nanometers, is less than 8 nanometers, is less than 5 nanometers, is less than 2 nanometers.As can be seen from Figure 13, when round number of times when the laser that laser instrument 20 exports is through repeatedly coming and going arrival the 3rd catoptron 1013 is 40, because laser is returned along former road by the 3rd catoptron 1013, so total order of reflection is 80 times, namely the feedback order of feedback fringe is 80, and corresponding optical resolution is 4nm.After first photodetector 9, second photodetector 10 detects this feedback fringe, filter amplification circuit 11 pairs of signals are utilized to carry out filter amplifying processing; Then utilize signal processing unit 12, realize the digital conversion of signal and further shaping, filtering, and the edge of two paths of signals is processed and realizes counting, and measurement result is presented in display device 13.
The present invention is based on the displacement measurement system of FP feedback exocoel, utilize the weak feedback effect of laser substance high-order, not only there is high-order frequency-doubled effect, reach nano level displacement measurement resolution; But also electronic fine-grainedly further can reach the Measurement Resolution of Subnano-class and the direction of motion of recognition object; In addition, the method also has the advantage of optical resolution self-calibration, just can obtain feedback order, thus obtain the resolution of displacement measurement system, and do not need other reference instrument to demarcate according to the order of reflection of FP feedback chamber mirror.Described displacement measurement system has that resolution is high, structure is simple, can be traceable to the features such as optical maser wavelength.
In addition, those skilled in the art also can do other change in spirit of the present invention, and these changes done according to the present invention's spirit, all should be included in the present invention's scope required for protection certainly.
Claims (5)
1. a displacement measurement system, mainly comprises:
One laser instrument, in order to export the double-frequency laser along Z-direction;
One data acquisition and processing unit, in order to receive the interference laser of laser instrument output and to carry out data processing;
It is characterized in that, comprise a feedback unit further, described feedback unit comprises one first catoptron, the second catoptron and one the 3rd catoptron, described first catoptron and interval relative with described second catoptron is arranged, described first catoptron has a first surface, and described first surface comprises an incidence zone, the first echo area, the first boot section, the second boot section;
Described incidence zone has multiple the 3rd groove extended in X direction;
Described first echo area has multiple the 4th groove extended in X direction, and described 4th groove and described 3rd groove are arranged side by side;
Described first boot section, the first echo area and described second boot section set gradually along Y-direction, and described first boot section has multiple the 5th groove extended along Y-direction;
Described second boot section has multiple the 6th groove extended along Y-direction, and described 6th groove and described 5th groove interlock corresponding setting;
Described second catoptron has a second surface and described first surface in the face of arranging, and described second surface has multiple the second groove extended in X direction; Wherein, the direction of laser instrument Output of laser is Z-direction, and the direction vertical with Z-direction is orthogonal X-direction and Y-direction;
The laser of laser instrument incidence is directly transmitted to the 3rd groove of described incidence zone, and reflex to described 4th groove through the second groove, one the 5th groove is incident to after multiple reflections between described 4th groove and described second groove, the 4th groove is again incident to after the 5th groove reflection, and described 6th groove is incident to after the reflection of the 4th groove and the second groove, after one the 6th groove reflection, be incident to described second groove; Described 3rd catoptron reflection from the laser of the second groove incidence described in described second catoptron, and makes described laser form laser feedback along in original optical path return laser light device after described 3rd catoptron reflection.
2. displacement measurement system as claimed in claim 1, it is characterized in that, in the X direction, described incidence zone is disposed adjacent with described second boot section, and described 3rd catoptron is arranged at one end away from incidence zone, described second boot section; In the Y direction, described first echo area is disposed adjacent with described incidence zone and the second boot section simultaneously; Described first boot section is disposed adjacent with described first echo area.
3. displacement measurement system as claimed in claim 1, it is characterized in that, described 3rd groove is corresponding with one first side in described 5th groove in the Y direction to be arranged, the laser that laser instrument exports, after the 3rd groove, reflection between the 4th groove and the second catoptron, incides described first side.
4. displacement measurement system as claimed in claim 1, it is characterized in that, the width of described 6th groove equals the width of described 5th groove.
5. displacement measurement system as claimed in claim 1, it is characterized in that, the optical resolution of described displacement measurement system is less than 5 nanometers.
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| CN104571141B (en) * | 2014-11-26 | 2017-06-16 | 中国人民解放军第二炮兵装备研究院第三研究所 | A kind of object verticality adjusting device and method based on optics feedback effect |
| CN104897064B (en) * | 2015-06-09 | 2018-06-01 | 张白 | A kind of new smooth arm amplifying type high precision length sensor and measuring method |
| CN105674888B (en) * | 2016-01-27 | 2018-07-06 | 广西科技大学鹿山学院 | Displacement measuring device based on the interference of light |
| CN105674889B (en) * | 2016-01-27 | 2018-07-06 | 广西科技大学鹿山学院 | Displacement measurement method based on the interference of light |
| CN106654839A (en) * | 2016-10-13 | 2017-05-10 | 南通大学 | Displacement self-sensing helium-neon laser system |
| CN108534688A (en) * | 2018-07-06 | 2018-09-14 | 北方民族大学 | The displacement sensor and its measurement method of amplification factor can be improved |
| CN108662984A (en) * | 2018-07-17 | 2018-10-16 | 北方民族大学 | A kind of precise displacement sensor and its measurement method based on corner cube mirror group |
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