CN101650158B - Differential planar reflector laser interference system for measuring linear displacement - Google Patents
Differential planar reflector laser interference system for measuring linear displacement Download PDFInfo
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- CN101650158B CN101650158B CN2008100541454A CN200810054145A CN101650158B CN 101650158 B CN101650158 B CN 101650158B CN 2008100541454 A CN2008100541454 A CN 2008100541454A CN 200810054145 A CN200810054145 A CN 200810054145A CN 101650158 B CN101650158 B CN 101650158B
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Abstract
The invention discloses a differential planar reflector laser interference system for measuring linear displacement, which consists of a laser source, a pentagonal polarizing beam splitter prism, a quarter wave plate b, a quarter wave plate c, a corner prism, a reference mirror, a measurement mirror, a polarizer, a photoelectric detector and a phase meter. The laser source generates incident beams with stable frequency, and meanwhile provides a stable reference signal source; the incident beams are reflected twice by the reference mirror and the measurement mirror under the action of the pentagonal polarizing beam splitter prism, the quarter wave plates and the corner prism respectively, and are emergent from the pentagonal polarizing beam splitter prism; through the interference of the polarizer, the photoelectric detector receives the emergent beams and generates electric measurement signals; and phases of the electric measurement signals and an electric reference signal are compared by the phase meter so as to measure the linear displacement of the measurement mirror which is fixedly connected with a detected piece. The differential planar reflector laser interference system has the advantages of simple structure, lower cost, small optical path dead area and high measurement precision, and can be widely applied to the precision measurement of geometrical quantity and construction of metering reference in the fields of war industry, aviation, numerical control machines and the like.
Description
(1) technical field
The present invention relates to the accurate laser measurement technology, particularly a kind of differential planar reflector laser interference system that is used to measure straight-line displacement.
(2) background technology
The differential planar reflector interferometer is a kind of Novel Laser Interferometer of the mid-80 development; Its principal feature is the optical resolution height and can makes the light path dead band reach minimum; Have advantages of higher stability and measuring accuracy; Can accomplish the canonical measure of parameters, like linear position precision, repetitive positioning accuracy, angle, linearity, verticality, the depth of parallelism etc., so be adapted to the measurement of various geometric sense delicate meterings and the foundation of benchmark; Comprise accurate benchmark metering such as military project, space flight; Can be used for calibrating various numerically-controlled machines and three coordinate measuring machine, and can be in order to location and other locating device of control grating ruling worktable, high-performance precise numerical control machine, for example nano measurement positioning table and scanning probe microscopy etc.The shortcoming of traditional differential planar reflector interferometer is the structure more complicated; Because auxiliary optical component is more; Therefore make that measuring beam must be through repeatedly reflection, the leakage that weakens with polarization state of beam energy makes that the measuring-signal signal to noise ratio (S/N ratio) is low, has also influenced the precision of measuring simultaneously.
(3) summary of the invention
The objective of the invention is to above-mentioned existing problems, provide a kind of simple in structure, measuring accuracy is high, cost is low and the differential planar reflector laser interference system that is used to measure straight-line displacement being convenient to produce.
Technical scheme of the present invention:
A kind of differential planar reflector laser interference system that is used to measure straight-line displacement is characterized in that: be made up of lasing light emitter, five polarization splitting prisms, quarter-wave plate b, quarter-wave plate c, corner cube, reference mirror, measurement mirror, the polarizer, photoelectric detector and phasometers; Said lasing light emitter produces the incident beam of stabilized frequency on the one hand to five polarization splitting prisms; This light beam contains the component of two frequency differences and linear polarization mutually orthogonal; Simultaneously also phasometer is provided a stable sinusoidal electric reference signal, the frequency of this reference signal equals the difference on the frequency of two components of lasing light emitter; Five polarization splitting prisms are bonded by two right-angle prisms; Be coated with one deck polarization beam splitter at cemented surface; The plane of incidence and the exit facet of light are coated with anti-reflection film; Cemented surface is equivalent to polarization spectroscope so be called polarization light-dividing surface; Be coated with anti-reflective film with prism facets a and the prism facets b of polarization light-dividing surface symmetry, its effect be through polarization light-dividing surface the polarization direction mutually orthogonal from the two light beams of prism facets a incident separately and after the reflection of prism facets a and prism facets b from prism facets c outgoing, again the light beam of reflected back prism facets c is synthesized one from prism facets a outgoing through polarization light-dividing surface at last; Quarter-wave plate b and quarter-wave plate c lay respectively at the both sides of prism facets b and prism facets c and in parallel, and its effect is that the linearly polarized light through quarter-wave plate is changed into circularly polarized light or will change into linearly polarized light through the circularly polarized light of quarter-wave plate; Back and its axis that corner cube is arranged on quarter-wave plate b are vertical with prism facets b; Corner cube will go back from the beam reflection of prism facets b outgoing and incident behind quarter-wave plate b, and incident beam and folded light beam is parallel to each other and not on a height; Reference mirror is successively set on the back of quarter-wave plate c and all parallel with prism facets c with the measurement mirror; Its effect is the light beam that reflects respectively from quarter-wave plate c; Reference mirror fixedly installs, measure that mirror links to each other with worktable and with measured piece do straight-line displacement and cause reference path and the measurement light path between the variation of optical path difference; The polarizer and prism facets a laterally arrange, and its effect is the pairwise orthogonal component that mixes from prism facets a outgoing beam; Photoelectric detector receives from the light beam of the polarizer and produces sinusoidal electric measurement signal input phase meter; Phasometer is used for measuring the phase differential between above-mentioned sinusoidal electric measurement signal and the electric reference signal of aforementioned sine, and this phase differential is varied to direct ratio with the optical path difference that the straight-line displacement of measurement mirror causes.
Said lasing light emitter is double-frequency laser or single-frequency polarization laser.
Said corner cube, quarter-wave plate b and prism facets b are centered close on the same axis.
Being centered close on the same axis of said prism facets c, quarter-wave plate c, reference mirror and measurement mirror.
Said reference mirror is provided with two holes and makes to shine from quarter-wave plate c and measure mirror and pass this hole from measuring the measuring light that mirror reflection returns quarter-wave plate c.
Principle of work of the present invention:
The incident beam and the outgoing beam of five polarization splitting prism polarization light-dividing surfaces of turnover; The frequency component that two polarization direction quadratures are all arranged; The component of each frequency has all passed through identical light path (air and glass) in five polarization splitting prisms; But it is not necessarily identical to come and go the light path of measuring mirror and reference mirror; Optical path difference nl between them can change with the displacement of measuring mirror, and (n is a medium refraction index of measuring light path and reference path, if when the medium refraction index of measurement light path and reference path is inequality, then get two medium refraction rate variances; L is that the geometric distance of measurement light path and reference path is poor).The variation of optical path difference nl causes the variation that produces phase differential through total system at last between two frequency components from the light beam of five polarization splitting prism outgoing.Phase change between measuring-signal and the reference signal records through phasometer, and it directly is proportional to the variation of measuring the optical path difference nl between light path and the reference path.If n remains unchanged, then the variation of phase differential directly is proportional to and measures the distance L that the mirror straight line moves.The characteristic that can find out this light path is very insensitive to extraneous interference, because the variation of other optical elements, and the error that causes like machinery or temperature, all acting in conjunction is in two frequency components, the therefore not influence of phase change to being surveyed.
Advantage of the present invention is: the required optical device of this instrument is few, and is simple in structure, be convenient to produce and processing, so cost is lower; Because light channel structure is to two frequency component symmetries; When the perhaps mechanical variation of temperature produces various the influence to optical element; All, can not cause the variation of phase differential between them, thereby reduce the possibility that produces error acting on two light frequency components simultaneously; So system stability can reach high-precision measurement index fully; Be specially adapted to the foundation of geometric sense precision measurement and mete-wand, comprising accurate benchmark metering such as military project, space flight, various numerically-controlled machine and the location of three-coordinates measuring machine or the location survey of calibration, grating ruling worktable and various measurement and positioning worktable etc.
(4) description of drawings
Fig. 1 is the structural representation of this laser interference system.
Fig. 2 is that the light path plane of this laser interference system launches synoptic diagram.
Among the figure: 1. 2. 5 polarization splitting prisms of lasing light emitter, 3. polarization light-dividing surfaces, 4. prism facets a, 5. prism facets b, 6. prism facets c, 7. quarter-wave plate b8. corner cubes, 9. quarter-wave plate c, 10. reference mirrors 11. are measured mirror 12. polarizers 13. photoelectric detectors 14. phasometers
All the other numberings are light beam among the figure.
(5) embodiment
Embodiment:
A kind of differential planar reflector laser interference system that is used to measure straight-line displacement; As shown in Figure 1, by lasing light emitter 1, five polarization splitting prisms 2, quarter-wave plate b7, quarter-wave plate c9, corner cube 8, reference mirrors 10, measure mirror 11, polarizer 12, photoelectric detector 13 and phasometer 14 and constitute; Said lasing light emitter 1 adopts double-frequency laser; Lasing light emitter 1 produces the incident beam of frequency stabilization on the one hand to five polarization splitting prisms 2; This light beam contains the component of two frequency differences and linear polarization mutually orthogonal; Simultaneously also phasometer 14 is provided a stable sinusoidal electric reference signal, the frequency of this reference signal equals the difference on the frequency of 1 two components of lasing light emitter; Five polarization splitting prisms 2 are bonded by two right-angle prisms; Be coated with one deck polarization beam splitter at cemented surface; The plane of incidence of light and exit facet are that prism facets a4 and prism facets c6 all are coated with anti-reflection film; Cemented surface is equivalent to polarization spectroscope so be called polarization light-dividing surface 3; The prism facets a4 and the prism facets b5 of polarization light-dividing surface 3 symmetries are coated with anti-reflective film relatively; Its effect is separately and after the reflection of prism facets a4 and prism facets b5 to shine the mutually orthogonal two light beams from prism facets a4 incident in polarization direction reference mirror 10 and measure mirror 11 through quarter-wave plate c9 from prism facets c6 through polarization light-dividing surface 3, and reference mirror 10 is provided with two apertures, makes measuring light can pass reference mirror 10; Arrive and measure mirror 11; Then the light beam of reflected back prism facets c6 is shone corner cube 8 from prism facets b5 together through polarization light-dividing surface 3 is synthetic, and through polarization light-dividing surface 3 the mutually orthogonal two light beams in the polarization direction that reflects by corner cube 8 separately, and after the reflection of prism facets a4 and prism facets b5, shine reference mirror 10 and measurement mirror 11 once more through quarter-wave plate c9 from prism facets c6; At last, again that the light beam of reflected back prism facets c6 is synthetic together from prism facets a4 outgoing through polarization light-dividing surface 3; Quarter-wave plate b7 and quarter-wave plate c9 lay respectively at the both sides of prism facets b5 and prism facets c6 and in parallel; Its effect is that the linearly polarized light through quarter-wave plate b7 and quarter-wave plate c9 is changed into circularly polarized light, perhaps conversely circularly polarized light is changed into linearly polarized light; Back and its axis that corner cube 8 is arranged on quarter-wave plate b7 are vertical with prism facets b5; Corner cube 8, quarter-wave plate b7 and prism facets b5 are centered close on the same axis; Corner cube 8 will go back from the beam reflection of prism facets b5 outgoing and incident behind quarter-wave plate b7, and incident beam and folded light beam is parallel to each other and not on a height; Reference mirror 10 is successively set on the back of quarter-wave plate c9 and all parallel with prism facets c6 with measurement mirror 11; Being centered close on the same axis of prism facets c6, quarter-wave plate c9, reference mirror 10 and measurement mirror 11; Reference mirror 10 is the light beams that reflect from quarter-wave plate c9 with the effect of measuring mirror 11; Reference mirror 10 fixedly installs, measure that mirror 11 links to each other with worktable and with measured piece do straight-line displacement and cause reference path and the measurement light path between the variation of optical path difference; The polarizer 12 laterally arranges with prism facets a4, and its effect is the pairwise orthogonal component that mixes from prism facets a4 outgoing beam; Photoelectric detector 13 receives from the light beam of the polarizer 12 and produces sinusoidal electric measurement signal input phase meter 14; Phasometer 14 is used for measuring the phase differential between above-mentioned sinusoidal electric measurement signal and the electric reference signal of aforementioned sine, and the variation of this phase differential is varied to direct ratio with the optical path difference that 11 straight-line displacements of measurement mirror cause.
Light path characteristic of the present invention:
Referring to Fig. 2, all light beams in this system (sequence number with in the bracket is represented) all are deployed in the same plane.Laser instrument 1 sends incident beam (15), and this light beam has two stable frequency components, and the polarization direction mutually orthogonal is represented with two arrows; This light source provides a reference signal simultaneously, and it equals the poor of two light stable frequencies.Light beam (15) incides five polarization splitting prisms 2; Wherein prism facets a4 and prism facets b5 surface are coated with anti-reflective film; Polarization light-dividing surface 3 is coated with polarization beam splitter, and the p light (16) of the parallel plane of incidence that two linear polarization are mutually orthogonal and the s light (17) of vertical incidence face are separately.After two light beams process prism facets a4 and the prism facets b5 reflection, penetrate five polarization splitting prisms 2, i.e. light beam (20) and (21).
Change into circularly polarized light beam (22) and (23) respectively behind light beam (20) and (21) process quarter-wave plate c9; Light beam (22) is become light beam (22A) by reference mirror 10 reflections; Meanwhile; Measurement mirror 11 reflections that light beam (23) quilt links to each other with worktable become light beam (23A), and the linear displacement amount of this worktable can record through the phase differential variation that produces between two frequency components; Light beam (22A) and (23A) change into polarization direction and former incident beam (20) and (21) mutually orthogonal linearly polarized light (24) and (25) through behind the quarter-wave plate c9 once more; Light beam (24) and (25) get into five polarization splitting prisms 2; After prism facets a4 and prism facets b5 reflection, be merged into light beam (28) at polarization light-dividing surface 3.Light beam (28) becomes light beam (29) through quarter-wave plate b7 after penetrating five polarization splitting prisms 2; Become light beam (30) after corner cube 8 reflections; Transform into light beam (31) through quarter-wave plate b7 then, because the characteristic of corner cube 8, light beam (29) and light beam (30) are parallel to each other.
Light beam (31) is five polarization splitting prisms 2 of incident once more, on polarization light-dividing surface 3, are divided into the orthogonal light in two bundle polarization directions (50) and (51); Become light beam (52) and five polarization splitting prisms 2 of (53) outgoing after light (50) and (51) process prism facets a4 and the prism facets b5 reflection, become light beam (54) and (55) through quarter-wave plate c9 then.Light beam (54) is formed light beam (54A) by reference mirror 10 reflection backs, and simultaneously, the measured mirror of light beam (55) 11 reflection backs form light beam (55A).Light beam (54A) and (55A) again form light beam (56) and (57) through quarter-wave plate c9, the polarization direction of light beam (56) and (57) is consistent with the polarization direction of elementary beam (21) and (20) at this moment; Light beam (56) and (57) get into five polarization splitting prisms 2, form light beam (58) and (59) through prism facets a4 and prism facets b5 reflection back, are merged into five polarization splitting prisms 2 of light beam (60) outgoing at polarization light-dividing surface 3.Light beam (60) together gets into phasometer 14 with light beam (15), so that measure the phase differential between sinusoidal electric measurement signal and the sinusoidal electric reference signal after passing through the polarizer 12 and photoelectric detector 13.
Claims (5)
1. a differential planar reflector laser interference system that is used to measure straight-line displacement is characterized in that: be made up of lasing light emitter, five polarization splitting prisms, quarter-wave plate b, quarter-wave plate c, corner cube, reference mirror, measurement mirror, the polarizer, photoelectric detector and phasometers; Said lasing light emitter produces the incident beam of stabilized frequency on the one hand to five polarization splitting prisms; This light beam contains the component of two frequency differences and linear polarization mutually orthogonal; Simultaneously also phasometer is provided a stable sinusoidal electric reference signal, the frequency of this reference signal equals the difference on the frequency of two components of lasing light emitter; Five polarization splitting prisms are bonded by two right-angle prisms; Be coated with one deck polarization beam splitter at cemented surface; The plane of incidence and the exit facet of light are coated with anti-reflection film; Cemented surface is equivalent to polarization spectroscope so be called polarization light-dividing surface; Be coated with anti-reflective film with prism facets a and the prism facets b of polarization light-dividing surface symmetry, its effect be through polarization light-dividing surface the polarization direction mutually orthogonal from the two light beams of prism facets a incident separately and after the reflection of prism facets a and prism facets b from prism facets c outgoing, again the light beam of reflected back prism facets c is synthesized one from prism facets a outgoing through polarization light-dividing surface at last; Quarter-wave plate b and quarter-wave plate c lay respectively at the both sides of prism facets b and prism facets c and in parallel, and its effect is that the light beam through quarter-wave plate is changed into circularly polarized light beam or will change into linearly polarized light through the circularly polarized light of quarter-wave plate; Back and its axis that corner cube is arranged on quarter-wave plate b are vertical with prism facets b; Corner cube will go back from the beam reflection of prism facets b outgoing and incident behind quarter-wave plate b, and incident beam and folded light beam is parallel to each other and not on a height; Reference mirror is successively set on the back of quarter-wave plate c and all parallel with prism facets c with the measurement mirror; Its effect is the light beam that reflects respectively from quarter-wave plate c; Reference mirror fixedly installs, measure that mirror links to each other with worktable and with measured piece do straight-line displacement and cause reference path and the measurement light path between the variation of optical path difference; The polarizer and prism facets a laterally arrange, and its effect is the pairwise orthogonal component that mixes from prism facets a outgoing beam; Photoelectric detector receives from the light beam of the polarizer and produces sinusoidal electric measurement signal input phase meter; Phasometer is used for measuring the phase differential between above-mentioned sinusoidal electric measurement signal and the electric reference signal of aforementioned sine, and this phase differential is varied to direct ratio with the optical path difference that the straight-line displacement of measurement mirror causes.
2. the differential planar reflector laser interference system that is used to measure straight-line displacement according to claim 1 is characterized in that: said lasing light emitter is double-frequency laser or single-frequency polarization laser.
3. the differential planar reflector laser interference system that is used to measure straight-line displacement according to claim 1 is characterized in that: said corner cube, quarter-wave plate b and prism facets b are centered close on the same axis.
4. the differential planar reflector laser interference system that is used to measure straight-line displacement according to claim 1 is characterized in that: being centered close on the same axis of said prism facets c, quarter-wave plate c, reference mirror and measurement mirror.
5. the differential planar reflector laser interference system that is used to measure straight-line displacement according to claim 1 is characterized in that: said reference mirror is provided with two holes and makes to shine from quarter-wave plate c and measure mirror and pass this hole from measuring the measuring light that mirror reflection returns quarter-wave plate c.
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| Application Number | Priority Date | Filing Date | Title |
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| CN2008100541454A CN101650158B (en) | 2008-08-15 | 2008-08-15 | Differential planar reflector laser interference system for measuring linear displacement |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN101907443B (en) * | 2010-06-23 | 2012-03-07 | 清华大学 | Displacement measuring device for movable mutual inductor of energy balance |
| CN102175141B (en) * | 2011-01-13 | 2013-06-12 | 清华大学 | Double-channel single-frequency laser interferometer |
| CN102506764B (en) * | 2011-10-14 | 2014-12-17 | 上海理工大学 | Laser interference system for displacement linearity measurement |
| CN106123769A (en) * | 2016-06-13 | 2016-11-16 | 上海理工大学 | The differential planar mirror laser interference device of without error |
| CN110160515B (en) * | 2019-04-15 | 2020-12-22 | 清华大学深圳研究生院 | Angular velocity measuring method, angular velocity measuring system and carrier |
| CN109917828B (en) * | 2019-04-15 | 2021-10-15 | 中国航空工业集团公司北京长城计量测试技术研究所 | Interference differential displacement method micro force control system |
| CN111397542B (en) * | 2020-03-09 | 2021-07-06 | 天地科技股份有限公司 | System and method for monitoring straightness of scraper conveyor based on weak reflection grating |
| CN112504154B (en) * | 2020-11-02 | 2022-06-03 | 南京信息工程大学滨江学院 | Large-size support structure deformation measuring device and measuring method based on optical path |
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