CN1673672A - Micro-corner interferometer - Google Patents
Micro-corner interferometer Download PDFInfo
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- CN1673672A CN1673672A CN 200510025282 CN200510025282A CN1673672A CN 1673672 A CN1673672 A CN 1673672A CN 200510025282 CN200510025282 CN 200510025282 CN 200510025282 A CN200510025282 A CN 200510025282A CN 1673672 A CN1673672 A CN 1673672A
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Abstract
The micro rotation angle interference measurement equipment has the structure comprising one modulated light source driven with one modulating driving power source; light beam collimating system, light beam reducing system and light splitting element successively arranged in the light beam direction; the first reflector and the first measuring arm assembly in the first outgoing light direction of the light splitting element; the second measuring arm assembly in the second outgoing light direction of the light splitting element; photoelectronic conversion element in the third outgoing light direction of the light splitting element; and signal amplifier, A/D converter and computer connected successively to the photoelectronic conversion element. The present invention has angular displacement measuring resolution in the magnitude of 10E(-8) rad, contrasting to 1.75E(-6) rad in available technology.
Description
Technical field
The present invention relates to micro-corner and measure, particularly a kind of interferometric measuring means of micro-corner.Be based on a kind of micro-corner interferometer of two right-angle prisms and phase modulation technique specifically.
Background technology
The detection of minute angle is having a wide range of applications aspect precision control and the precision positioning.Because the raising of production and processing automaticity, the requirements such as science that the high efficiency of scientific experiment process and error are traced to the source are had higher requirement to the detection of corner in the testee spatial degrees of freedom.For example in the industrial processes control operation, the realization that the small rotation angle of some workbench detects, whether the object that moves along a straight line departs from the monitoring of its movement locus, all need be finished by high-precision precise detection technology.In the prior art, though the laser measurement system of people such as Kam C.Lau invention can carry out the detection of multidimensional micro-corner, but because it takes into account multivariant measurement, the measuring accuracy of its corner on certain single-degree-of-freedom is restricted, its precision is 0.1 " (referring to technology [1] United States Patent formerly, Patent Number:6049377).P.Shi and E.Stijns in 1988 has proposed a kind of little rotation angle measuring method (referring to technology [2] formerly, " New Optical Methodfor Measuring Small-angle Rotations; Applied Optics, Vol.27 Issue 20 Page4342 (October 1988) ").Because of it adopts interference fringe probe method detectable signal, when for the optical path difference of the two-beam that interferes the variation of a half-wavelength being arranged, the intensity distributions of interference fringe just has a light and shade to change.To come the correct measurement optical path difference be impossible less than the micro-corner of half-wavelength and only change according to the light and shade of interference fringe, and this causes the raising of its Measurement Resolution to be restricted.Formerly the resolution that provides in the technology [2] is 10
-4Degree (1.75*10
-6Rad).Want with the more detection of done with high accuracy micro-corner, formerly technology [1] and formerly technology [2] obviously do not reach the accuracy of detection requirement.Because formerly the light source that adopts in the technology [2] is the He-Ne laser instrument, can't modulates output wavelength, thereby limit use based on the accurate heterodyne technology of internal modulation mode.The method initial position of requiring to incide two right-angle prisms wants strict guarantee identical in addition, and this gives experimental debugging, operates and bring great difficulty.
Summary of the invention
The objective of the invention is to overcome the weak point in the above-mentioned technology formerly, a kind of micro-corner interferometer is provided, angle displacement measurement resolution is brought up to 10
-8The rad order of magnitude.
Technical solution of the present invention is as follows:
A kind of micro-corner interferometer, be characterised in that its structure is: a modulated light source is driven by modulation driving power supply, on the working direction of the light beam that this modulated light source is sent, be placed with passing through a collimating system successively, light beam contract beam system and beam splitter, on the working direction of the first outgoing beam a of this beam splitter, be placed with first reflective mirror, on the working direction of the outgoing beam d of this first reflective mirror, be placed with the first gage beam assembly, on the working direction of the outgoing beam of the first gage beam assembly, be placed with second reflective mirror, on the working direction of the second outgoing beam b of described beam splitter, be placed with the second gage beam assembly, on the working direction of the outgoing beam of the second gage beam assembly, be placed with the 3rd reflective mirror, on the working direction of the 3rd outgoing beam c of described beam splitter, be placed with photo-electric conversion element, the output terminal of this photo-electric conversion element links to each other with the input end of signal amplifier, the output terminal of this signal amplifier links to each other with analog to digital converter, and this analog to digital converter links to each other with computing machine.
Described modulation driving power supply provides direct current driven signal and alternating current drive signal to light source.
Described light source is the semiconductor laser instrument.
Described passing through a collimating system is made up of microcobjective and lens.
The described light beam beam system that contracts is meant the incident collimated light to be contracted by certain multiple and restraints the optical system of thin and collimated light beam.
Described beam splitter is an Amici prism, or the parallel flat of analysing light film and anti-reflection film is plated on the two sides respectively.
Described first reflecting element is the catoptron of high reflectance.Described second reflecting element and the 3rd reflecting element are two identical and have a reflective mirror of high reflectance.Described gage beam assembly is right-angle prism or prism of corner cube.
Described photo-electric conversion element is photodiode or photoelectric cell.
The measuring accuracy that incides the initial separation d between two light beams on the first gage beam assembly and the second gage beam assembly is 50-200 μ m.
The present invention has following outstanding feature:
1, the present invention compares with technology [2] formerly, utilizes semiconductor laser to do light source, by changing injection current the wavelength of light source is modulated, and this is a kind of phase modulating method based on the internal modulation mode.When signal Processing, can pass through fast fourier transform, obtain required low order spectrum component information, be equivalent to interference signal has been carried out filtering, reduced measuring error, strengthened antijamming capability to parasitic light.
2, the present invention compares with technology [2] formerly, owing to directly measure the distance between two light beams that incide on the two measuring arm assembly, saved accurate measurement to the hypotenuse length and the two prisms spacing of right-angle prism, and making the initial position that incides the light beam on two right-angle prisms not need strict symmetry, this makes that measuring debugging work obtains very big simplification.
3, the present invention compares with formerly technology [1], [2], and measuring accuracy has improved two orders of magnitude.
4, the present invention compares with the He-Ne laser instrument of the middle use of technology [2] formerly, owing to use semiconductor laser, has dwindled weight, the volume of measurement mechanism, and this interference measuring instrument also has advantages such as price is low, power-saving simultaneously.
Description of drawings
Fig. 1 is the structural representation of micro-corner interferometer most preferred embodiment of the present invention.
Fig. 2 is the gage beam synoptic diagram that is made of two right-angle prisms of the present invention.
Fig. 3 is the vertical view of the configuration of gage beam of the present invention on tested rotation platform.
Embodiment
The invention will be further described below by embodiment and accompanying drawing thereof.
See also Fig. 1 earlier, Fig. 1 is the structural representation of micro-corner interferometer most preferred embodiment of the present invention.As seen from the figure, the structure of micro-corner interferometer of the present invention is: a semiconductor laser modulation 2 is driven by modulation driving power supply 1, on the working direction of the light beam that this semiconductor laser modulation 2 sends, be placed with passing through a collimating system 3 successively, light beam contract beam system 4 and Amici prism 5, on the working direction of the first outgoing beam a of this Amici prism 5, be placed with first reflective mirror 6, on the working direction of the outgoing beam d of this first reflective mirror 6, be placed with first right-angle prism 71, on the working direction of the outgoing beam of first right-angle prism 71, be placed with second reflective mirror 81, on the working direction of the second outgoing beam b of described Amici prism 5, be placed with second right-angle prism 72, on the working direction of the outgoing beam of second right-angle prism 72, be placed with the 3rd reflective mirror 82, on the working direction of the 3rd outgoing beam c of described Amici prism 5, be placed with photodiode 9, the output terminal of this photodiode 9 links to each other with the input end of signal amplifier 10, the output terminal of this signal amplifier 10 links to each other with analog to digital converter 11, and this analog to digital converter 11 links to each other with computing machine 12.
Described modulation driving power supply 1 provides direct current driven signal and alternating current drive signal for semiconductor laser 2.
Described first reflecting element 6 is the catoptron of high reflectance.Second reflecting element 81 and the 3rd reflecting element 82 are reflective mirrors of two identical high reflectances.
Incide the initial separation d between two light beams on first right-angle prism 71 and second right-angle prism 72
0Measuring accuracy be 50-200 μ m.Described d
0Measuring accuracy require to be not more than 200 μ m.Available linear array photoelectric coupled device (CCD) is measured.
The course of work of apparatus of the present invention is as follows:
Modulation driving power supply 1 makes the light wavelength of being sent by semiconductor laser 2 by Sine Modulated for semiconductor laser 2 provides direct current driven signal and simple sinusoidal alternating current drive signal.Modulated light is earlier after passing through a collimating system 3 collimates, the beam system 4 that contracts contracts bundle, is divided into transmitted light path a and folded light beam b by Amici prism 5 again.Transmitted light beam a incides on first right-angle prism 71 through reflecting element 6 reflection, is incided on second reflecting element 81 by the light of right-angle prism 71 outgoing and reflects, and makes light beam be back to Amici prism 5 along original optical path.Folded light beam b incides on second right-angle prism 72, by the light of second right-angle prism, 72 outgoing, incides on the 3rd reflecting element 82 and also reflects, and makes light beam be back to Amici prism 5 along original optical path.Two-beam along the c direction outgoing of Amici prism 5 interferes.This interfering beam contains the micro-corner information of testee, is received by photodiode 9, and light signal is converted to electric signal.Signal amplifier 10 is sent into analog to digital converter 11 after this electric signal is amplified, and converts input computing machine 12 after the digital signal to, passes through the data processing and the computing of computing machine 12 again, solves the micro-corner information of testee.
Photodiode 9 detected interference light signals are:
A(t)＝A
0(t)+g
0(t)cos[zcos(ωt+)+γ(t)] (1)
Wherein, A
0(t) and g
0(t) be respectively the amplitude of the DC component and the AC compounent of interference signal; Z is the amplitude of the phase modulation (PM) of interference signal A (t); ω is the frequency of the modulation signal of driving power 1; T is the time; is the initial phase of modulation signal; γ (t) is the turntable to be measured phase changing capacity that interference signal A (t) produces when rotating.Wherein
γ(t)＝4πd
0δ(t)/λ
0 (2)
δ (t) is the corner size, d
0For inciding the initial separation between two light beams on two right-angle prisms, as shown in Figure 2, d
0Value can be measured by line array CCD.λ
0Be the luminous centre wavelength of laser instrument.When data processing,, solve the fundamental frequency F (ω) of this interference signal and the spectrum component of two frequency multiplication F (2 ω) and be shown below by the interference signal shown in (1) formula is carried out Fourier transform:
J wherein
1(z), J
2(z) be respectively single order, second order Bei Saier function.The expression that can be solved phase place γ (t) by (3) formula and (4) formula is shown:
And then just can obtain the size of tested corner according to (5) formula, promptly
δ(t)＝γ(t)λ
0/4πd
0 (6)
Have according to theory of errors:
Wherein the measuring accuracy of γ (t) reaches 0.010 radian and can realize; d
0Value is generally greater than 10 millimeters, and its measuring accuracy is not more than 200 microns and also can realizes.According to (7) formula as can be known, the Measurement Resolution of tested corner can reach 10
-8The radian order of magnitude.
Tested turntable as shown in Figure 3.During use the first gage beam assembly is fixed on the tested turntable 13 according to following position relation with the second gage beam assembly, two identical right-angle prism P1, P2 mirror M 1, the M2 identical with two.The hypotenuse of P1, P2 remains on the same horizontal linear, and the reflecting surface of M1, M2 also is positioned at same plane and parallel with the hypotenuse of P1, P2.
The structural representation of measurement mechanism as shown in Figure 1: semiconductor laser 2 is a light source, its luminescent center wavelength X
0Be 660nm.The light that light source 2 sends is through passing through a collimating system 3 collimation, again by the beam system that contracts by the beam ratio that the contracts bundle that contracts at 5: 1.Light beam behind the collimation is that 1: 1 Amici prism 5 is divided into two bundles by splitting ratio, this two-beam is again by the mirror reflects in the gage beam, carry information measured, after closing bundle, Amici prism 5 surveys interference signal once more by photodiode 9, then after signal amplifier 10 amplifies signal, undertaken sending into the computing machine 12 that the Fourier transform processing program is housed after the analog to digital conversion by A/D converter 11 and carry out data processing.When rotation platform around rotation center one micro-corner δ=θ takes place
2-θ
1The time, as shown in Figure 2.The phase differential γ (t) of two interfering beams is:
γ(t)＝4πd
0(tanθ
2-tanθ
1)/λ
0 (8)
θ wherein
1, θ
2Be respectively t
1, t
2Corresponding constantly corner; d
0For inciding the initial separation between two light beams on two right-angle prisms.When θ≤5 °, tan θ ≈ θ.Therefore have:
γ(t)＝4πd
0(θ
2-θ
1)/λ＝4πd
0δ/λ
0 (9)
δ(t)＝γ(t)λ
0/4πd
0 (10)
As seen δ and γ are a kind of linear relationships.
Adopting DC current is the drive current drive laser of 70mA, is the output wavelength λ of the sinusoidal pattern exchange current semiconductor laser modulation of 1mA by injecting amplitude again, promptly have,
λ＝λ
0+Δλ＝λ
0+βacos(wt+φ) (11)
λ wherein
0Centre wavelength for laser instrument output; Δ λ is for injecting the wavelength variable quantity that causes behind the exchange current; β is the wavelength-current coefficient of semiconductor laser, and a is the amplitude of sinusoidal alternating current.By the interference signal that photodiode 9 detects, its AC compounent g (t) can be expressed as:
g(t)＝g
0(t)cos[zcos(ωt+)+γ
0+γ(t)] (12)
Wherein z is the phase modulation (PM) amplitude of interference signal g (t); And g
0(t), the symbol implication of , γ (t), t etc. is identical with described implication in (1) formula.This interference signal is sent into computing machine 12 through analog to digital converter 11 and is carried out data processing after being amplified by signal amplifier 10.By interference signal is carried out Fourier transform, extract relevant frequency spectrum information, phase place γ (t) can be drawn by (5) formula again, thereby the information of the micro-corner δ (t) of tested rotation platform can be obtained.With γ=2.350rad, d=15.7000mm, Δ γ=0.010rad, Δ d=200.0 μ m and λ
0The every numerical value of=660nm treats that the Measurement Resolution of this micro-corner can reach 6.7*10 as can be known into (7) formula
-8The rad order of magnitude.
Claims (10)
1, a kind of micro-corner interferometer, be characterised in that its structure is: a modulated light source (2) is driven by modulation driving power supply (1), on the working direction of the light beam that this modulated light source (2) is sent, be placed with passing through a collimating system (3) successively, light beam contract beam system (4) and beam splitter (5), on the working direction of the first outgoing beam a of this beam splitter (5), be placed with first reflective mirror (6), on the working direction of the outgoing beam d of this first reflective mirror (6), be placed with the first gage beam assembly (71), on the working direction of the outgoing beam of the first gage beam assembly (71), be placed with second reflective mirror (81), on the working direction of the second outgoing beam b of described beam splitter (5), be placed with the second gage beam assembly (72), on the working direction of the outgoing beam of the second gage beam assembly (72), be placed with the 3rd reflective mirror (82), on the working direction of the 3rd outgoing beam c of described beam splitter (5), be placed with photo-electric conversion element (9), the output terminal of this photo-electric conversion element (9) links to each other with the input end of signal amplifier (10), the output terminal of this signal amplifier (10) links to each other with analog to digital converter (11), and this analog to digital converter (11) links to each other with computing machine (12).
2, micro-corner interferometer according to claim 1 is characterized in that described driving power (1) provides direct current driven signal and alternating current drive signal to light source (2).
3, micro-corner interferometer according to claim 1 is characterized in that described light source (2) is the semiconductor laser instrument.
4, micro-corner interferometer according to claim 1 is characterized in that described passing through a collimating system (3) is made up of microcobjective and lens.
5, micro-corner interferometer according to claim 1 is characterized in that the described light beam beam system (4) that contracts is meant the incident collimated light to be contracted by certain multiple and restraints the optical system of thin and collimated light beam.
6, micro-corner interferometer according to claim 1 it is characterized in that described beam splitter (5) is an Amici prism, or the parallel flat of analysing light film and anti-reflection film is plated on the two sides respectively.
7, micro-corner interferometer according to claim 1, it is characterized in that described first reflecting element (6) is the catoptron of high reflectance, second reflecting element (81) and the 3rd reflecting element (82) are two identical and have a reflective mirror of high reflectance.
8, micro-corner interferometer according to claim 1 is characterized in that described gage beam assembly is right-angle prism or prism of corner cube.
9, micro-corner interferometer according to claim 1 is characterized in that described photo-electric conversion element (11) is photodiode or photoelectric cell.
10, micro-corner interferometer according to claim 1, the measuring accuracy that it is characterized in that inciding the initial separation d between two light beams on first right-angle prism or prism of corner cube (71) and second right-angle prism or the prism of corner cube (72) is 50-200 μ m.
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|---|---|---|---|
| CNB2005100252821A CN1322308C (en) | 2005-04-21 | 2005-04-21 | Micro-corner interferometer |
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| CN1322308C CN1322308C (en) | 2007-06-20 |
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104748671A (en) * | 2015-03-05 | 2015-07-01 | 哈尔滨工业大学 | Nonlinear error correcting method and device for angular displacement type single-frequency laser interferometer |
| CN108398104A (en) * | 2018-02-01 | 2018-08-14 | 中国科学院国家天文台南京天文光学技术研究所 | The photoelectricity dynamic angle measuring devices and its method of random error can be reduced |
Family Cites Families (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| NL8005258A (en) * | 1980-09-22 | 1982-04-16 | Philips Nv | INTERFEROMETER. |
| CN2193993Y (en) * | 1994-02-03 | 1995-04-05 | 艾勇 | Feedback laser interferometer |
| CN1275712A (en) * | 1999-05-27 | 2000-12-06 | 中国科学院光电技术研究所 | Laser interference length-measuring method |
| JP2002148025A (en) * | 2000-11-09 | 2002-05-22 | Ricoh Co Ltd | Three-dimensional shape measuring apparatus |
| JP2002311404A (en) * | 2001-04-16 | 2002-10-23 | Nikon Corp | Modulated light generator, interference measuring instrument by light wave, exposure device, and method for manufacturing micro device |
| CN1176346C (en) * | 2003-01-22 | 2004-11-17 | 浙江工程学院 | Dual frequency laser synthesized wavelength interferometer |
| CN1170122C (en) * | 2003-04-11 | 2004-10-06 | 中国科学院上海光学精密机械研究所 | High precision double F-P angle displacement measuring apparatus |
| CN1231743C (en) * | 2004-05-19 | 2005-12-14 | 哈尔滨工业大学 | Optical grating wedge plate and corner measuring device using same |
-
2005
- 2005-04-21 CN CNB2005100252821A patent/CN1322308C/en not_active Expired - Fee Related
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104748671A (en) * | 2015-03-05 | 2015-07-01 | 哈尔滨工业大学 | Nonlinear error correcting method and device for angular displacement type single-frequency laser interferometer |
| CN104748671B (en) * | 2015-03-05 | 2017-09-05 | 哈尔滨工业大学 | Angular displacement single frequency laser interferometer nonlinearity erron modification method and device |
| CN108398104A (en) * | 2018-02-01 | 2018-08-14 | 中国科学院国家天文台南京天文光学技术研究所 | The photoelectricity dynamic angle measuring devices and its method of random error can be reduced |
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| CN1322308C (en) | 2007-06-20 |
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