CN101581577B - Device for measuring straightness accuracy and position thereof based on double frequency interference principle - Google Patents

Abstract

The invention discloses a method for measuring straightness accuracy and positions thereof based on double frequency interference principle. The measuring method adopts an optical laser outputting g cross-line polarized lights, a common spectroscope, a depolarization dispersion prism, a polarization splitting prism, a Wollaston prism, three analyzers, three photodevices and a measurement reflecting mirror comprising a right-angle prism. The measuring method utilizes the dichroism and polarization property of optical devices to make up a double light path measurement structure based on the heterodyne interference principle; the simultaneous measurement of the straightness accuracy and the positions thereof is realized by measuring the optical path difference of the double path, thus having measuring accuracy of the nanometer straightness accuracy and the positions thereof. The method is mainly applied in the motion displacement measurement of an accurate work table, the straightness accuracy detection of an accurate guide rail and the like belonging to fields such as super-precision processing technology, micro-photo dynamoelectric systems, integrated circuit chip manufacturing technology, etc.

Description

Based on the linearity of double frequency principle of interference and the measurement mechanism of position thereof

Technical field

The present invention relates to adopt optical means is the measurement mechanism of feature, especially relates to a kind of based on the linearity of double frequency principle of interference and the measurement mechanism of position thereof.

Background technology

Make a general survey of the measuring method of domestic and international linearity, according to having or not linear datum, the measuring method of linearity roughly can be divided into two classes: the first kind is the measuring method of no linear datum, the main error separation method that adopts, and the approach difference of obtaining according to information, no linear datum mensuration can be divided into reverse method again, dislocation method and many gauge heads method, error separation method is practical reliable, be applicable to online or off-line measurement, one-shot measurement can obtain multinomial measuring error, but this method is subjected to influence of various factors, and it is improper to select as the measurement mechanism structural parameters, the gauge head interval error, transducer calibration errors etc. descend accuracy of measurement.Second class is the measuring method that linear datum is arranged, this method adopts certain linear datum, and detect the straightness error of measured surface with this benchmark, mainly contain: light gap method, pitch method, dial gauge method, three-dimensional method, optical flat interferometric method, method of laser alignment, laser holographic method and double-frequency laser interference method etc.More than in these measuring methods, have the advantage of nanoscale high measurement accuracy based on the verticality measuring method of double-frequency laser interference, but it only is the independent measurement that has realized linearity, have the technical matters of the particular location that does not provide tested linearity.

Summary of the invention

The object of the present invention is to provide a kind of based on the linearity of double frequency principle of interference and the measurement mechanism of position thereof.Adopt the laser heterodyne interference principle, both realized the straight line degree measurement of nano-precision, realized that again the nano-grade displacement of tested linearity position is measured, solved the simultaneously-measured technical matters of high-precision linearity of nanoscale and position thereof.

The technical solution adopted for the present invention to solve the technical problems is:

Light source is that the laser beam that transverse zeeman effect He-Ne two-frequency laser sends is divided into two bundles through common spectroscope, first folded light beam is incident to first analyzer, received conduct with reference to signal by first photodetector, first transmitted light beam is divided into second folded light beam and second transmitted light beam once more through the depolarization Amici prism, second folded light beam incides polarization splitting prism, second transmitted light beam after the wollaston prism transmission with f ₁And f ₂The light of two frequencies is divided into the two-way measuring beam, and the measurement catoptron that directive is made up of right-angle prism is measured catoptron and is positioned on the measurand, measures catoptron and when mobile, produce and contain Doppler frequency difference ± Δ f on measurand ₁With ± Δ f ₂Two measuring beam f ₁± Δ f ₁And f ₂± Δ f ₂, another point to wollaston prism after measuring mirror reflects merges into a branch of light, and through directive polarization splitting prism behind the wollaston prism, wherein, frequency is f once more ₁± Δ f ₁The transmittance polarization splitting prism and second folded light beam in be f through the frequency of polarization splitting prism reflection ₂Light form first via measuring beam, frequency is f ₂± Δ f ₂Light frequency through the polarization splitting prism transmission in the polarization splitting prism reflection back and second folded light beam be f ₁Light form the second drive test amount light beam; First via measuring beam is incident to second analyzer, the pairwise orthogonal linearly polarized light angle at 45 of shake the thoroughly direction and the first via measuring beam of analyzer, the linearly polarized light of pairwise orthogonal is decomposed on the same direction of shaking, form beat frequency, received formation first via measuring-signal by second photodetector, its frequency is f ₁-f ₂± Δ f ₁The second drive test amount light beam incident the 3rd analyzer, the pairwise orthogonal linearly polarized light angle at 45 of shake the thoroughly direction and the second drive test amount light beam of analyzer, the linearly polarized light of pairwise orthogonal is decomposed on the same direction of shaking, form beat frequency, received the formation second drive test amount signal by the 3rd photodetector, its frequency is f ₁-f ₂± Δ f ₂, first via measuring-signal, the second drive test amount signal and reference signal process and display linearity that can obtain measuring and position thereof through follow-up data acquisition and machine calculation machine.

The beneficial effect that the present invention has is:

(1) based on the measuring method of the linearity of double frequency principle of interference and position thereof when measuring linearity, can locate the absolute position of linearity, measure when having realized linearity and position thereof, this greatly facilitates the application in the reality.

(2) this measuring method has adopted the laser heterodyne interference method, has the nanoscale measuring accuracy.

(3) adopt light channel structure altogether, help eliminating Effect of Environmental.

(4) light channel structure is simple, and is easy to use.

The present invention mainly is applicable to the moving displacement measurement of the precision stage that fields such as Ultraprecision Machining, Micro-Opto-Electro-Mechanical Systems, integrated circuit (IC) chip manufacturing technology are related, the linearity detection of precise guide rail etc.

Description of drawings

Fig. 1 is based on the index path of the measurement mechanism of the linearity of double frequency principle of interference and position thereof.

Fig. 2 is based on the synoptic diagram of the measuring method of the linearity of double frequency principle of interference and position thereof.

Among the figure: 1, two-frequency laser, 2, common spectroscope, 3, first analyzer, 4, first photodetector, 5, depolarization Amici prism, 6, wollaston prism, 7, measure catoptron, 8, polarization splitting prism, 9, second analyzer, 10, second photodetector, the 11, the 3rd analyzer, 12, the 3rd photodetector, 13, measurand.

Embodiment

The invention will be further described below in conjunction with drawings and Examples.

Based on the measuring method of the linearity of double frequency principle of interference and position thereof as shown in Figure 1: light source is a transverse zeeman effect He-Ne two-frequency laser 1, and the centre wavelength of this laser instrument is 632.8nm, two different frequency f of output ₁And f ₂Orhtogonal linear polarizaiton light, its frequency difference is 1.9MHz.The laser beam that laser instrument 1 sends is divided into two bundles through common spectroscope 2, wherein folded light beam is incident to first analyzer 3, because shake the thoroughly direction and the pairwise orthogonal linearly polarized light angle at 45 of analyzer, the linearly polarized light of pairwise orthogonal can be decomposed on the same direction of shaking, form beat frequency, received conduct with reference to signal by first photodetector 4, its frequency is f ₁-f ₂, transmitted light beam is divided into second folded light beam and second transmitted light beam once more through depolarization Amici prism 5, second folded light beam incide polarization splitting prism 8, the second transmitted light beams after wollaston prism 6 transmissions with f ₁And f ₂The light of two frequencies is divided into the two-way of certain angle measuring beam, and the measurement catoptron 7 that directive is made up of right-angle prism is measured catoptron and is positioned on the measurand 13, measures catoptron after moving on the measurand, produces and contains Doppler frequency difference ± Δ f ₁With ± Δ f ₂Two measuring beam f ₁± Δ f ₁And f ₂± Δ f ₂, another point to wollaston prism 6 after measuring catoptron 7 reflections merges into a branch of light, sees through wollaston prism 6 back directive polarization splitting prisms 8 once more, and wherein, frequency is f ₁± Δ f ₁Transmittance polarization splitting prism 8 and second folded light beam in be f through the frequency of polarization splitting prism 8 reflection ₂Light form first via measuring beam, frequency is f ₂± Δ f ₂Light frequency through polarization splitting prism 8 transmissions in the polarization splitting prism 8 reflection back and second folded light beam be f ₁Light form the second drive test amount light beam; First via measuring beam is incident to second analyzer 9, the pairwise orthogonal linearly polarized light angle at 45 of shake the thoroughly direction and the first via measuring beam of analyzer, the linearly polarized light of pairwise orthogonal can be decomposed on the same direction of shaking, form beat frequency, received formation first via measuring-signal by second photodetector 10, its frequency is f ₁-f ₂± Δ f ₁The second drive test amount light beam incident the 3rd analyzer 11, the pairwise orthogonal linearly polarized light angle at 45 of shake the thoroughly direction and the second drive test amount light beam of analyzer, the linearly polarized light of pairwise orthogonal can be decomposed on the same direction of shaking, form beat frequency, received the formation second drive test amount signal by the 3rd photodetector 12, its frequency is f ₁-f ₂± Δ f ₂, first via measuring-signal, the second drive test amount signal and reference signal process and display linearity that can obtain measuring and position thereof through follow-up data acquisition and machine calculation machine.

The hardware circuit data acquisition system (DAS) that specifically is the fpga chip EP2C20Q240 through producing based on altera corp is connected to the computer system that is used for data processing and demonstration.

As shown in Figure 1, the stain in the light path and vertically short-term represent the linearly polarized light of two different frequencies of polarization direction quadrature, and the top has the stain of triangle and the vertical short-term representative that has a triangle contains the orhtogonal linear polarizaiton light of Doppler frequency difference information.

In conjunction with shown in Figure 2, the linearity of this method and the measurement of position thereof are implemented as follows:

During measurement, establishing and measure catoptron 7 and move to measured position 2 by initial position 1, is v along the speed of measuring basis axis direction, according to Doppler effect and shown in Figure 2 getting:

${{\mathrm{<figure-callout\; id="1"\; label="f"\; filenames="H2009101000686E00011.png"\; state="\{\{state\}\}">f</figure-callout>}}_1}^{\&prime;}=f_1(1\&PlusMinus;\frac{2v\cos \frac{\mathrm{\&theta;}}{2}}{c})$

${{\mathrm{<figure-callout\; id="2"\; label="f"\; filenames="H2009101000686E00011.png"\; state="\{\{state\}\}">f</figure-callout>}}_2}^{\&prime;}=f_2(1\&PlusMinus;\frac{2v\cos \frac{\mathrm{\&theta;}}{2}}{c})$

In the formula: f ₁, f ₂Be two frequencies of two-frequency laser output orthogonal linearly polarized light, f ' ₁, f ₂' for containing two frequencies of Doppler frequency difference, c is a light speed in a vacuum, θ is the beam splitting angle of wollaston prism.

Speed is that v just gets when measuring catoptron 7 with the laser instrument move toward one another, and to be that v gets negative for speed during opposing motion.The measuring beam f that causes by Doppler effect ₁And f ₂Frequency change be:

$\mathrm{\&Delta;}{\mathrm{<figure-callout\; id="1"\; label="f"\; filenames="H2009101000686E00011.png"\; state="\{\{state\}\}">f</figure-callout>}}_1={{\mathrm{<figure-callout\; id="1"\; label="f"\; filenames="H2009101000686E00011.png"\; state="\{\{state\}\}">f</figure-callout>}}_1}^{\&prime;}-{\mathrm{<figure-callout\; id="1"\; label="f"\; filenames="H2009101000686E00011.png"\; state="\{\{state\}\}">f</figure-callout>}}_1=\&PlusMinus;\frac{2v\cos \frac{\mathrm{\&theta;}}{2}}{\mathrm{<figure-callout\; id="1"\; label="c\; f"\; filenames="H2009101000686E00011.png"\; state="\{\{state\}\}">c</figure-callout>}}{f}_{}{}_1=\&PlusMinus;\frac{v\cos \frac{\mathrm{\&theta;}}{2}}{\frac{1}{2}\frac{\mathrm{<figure-callout\; id="1"\; label="c\; f"\; filenames="H2009101000686E00011.png"\; state="\{\{state\}\}">c</figure-callout>}}{f_{}}}=\&PlusMinus;\frac{v\cos \frac{\mathrm{\&theta;}}{2}}{\frac{{\mathrm{\&lambda;}}_1}{2}}$

$\mathrm{\&Delta;}{\mathrm{<figure-callout\; id="2"\; label="f"\; filenames="H2009101000686E00011.png"\; state="\{\{state\}\}">f</figure-callout>}}_2={{\mathrm{<figure-callout\; id="2"\; label="f"\; filenames="H2009101000686E00011.png"\; state="\{\{state\}\}">f</figure-callout>}}_2}^{\&prime;}-{\mathrm{<figure-callout\; id="2"\; label="f"\; filenames="H2009101000686E00011.png"\; state="\{\{state\}\}">f</figure-callout>}}_2=\mathrm{\&mu;}\frac{2v\cos \frac{\mathrm{\&theta;}}{2}}{\mathrm{<figure-callout\; id="2"\; label="c\; f"\; filenames="H2009101000686E00011.png"\; state="\{\{state\}\}">c</figure-callout>}}{f}_{}{}_2=\mathrm{\&mu;}\frac{v\cos \frac{\mathrm{\&theta;}}{2}}{\frac{1}{2}\frac{\mathrm{<figure-callout\; id="2"\; label="c\; f"\; filenames="H2009101000686E00011.png"\; state="\{\{state\}\}">c</figure-callout>}}{f_{}}}=\mathrm{\&mu;}\frac{v\cos \frac{\mathrm{\&theta;}}{2}}{\frac{{\mathrm{\&lambda;}}_2}{2}}$

In the formula: λ ₁, λ ₂Be the optical maser wavelength of two frequencies.

If measuring catoptron 7 displacements is that S, time are t, (frequency is f by reference signal ₁-f ₂) and first via measuring-signal (frequency is f ₁-f ₂± Δ f ₁) ask difference frequency can get Δ f ₁, (frequency is f by reference signal ₁-f ₂) and the second drive test amount signal (frequency is f ₁-f ₂± Δ f ₂) ask difference frequency can get Δ f ₂, then the light path (displacement) of Dui Ying two light paths is changed to:

${\mathrm{<figure-callout\; id="1"\; label="L"\; filenames="H2009101000686E00011.png"\; state="\{\{state\}\}">L</figure-callout>}}_1={\&Integral;}_0^{t}v\cos \frac{\mathrm{\&theta;}}{2}\mathrm{dt}=\frac{{\mathrm{\&lambda;}}_1}{2}{\&Integral;}_0^t\mathrm{\&Delta;}{\mathrm{<figure-callout\; id="1"\; label="f"\; filenames="H2009101000686E00011.png"\; state="\{\{state\}\}">f</figure-callout>}}_1\mathrm{dt}$

${\mathrm{<figure-callout\; id="2"\; label="L"\; filenames="H2009101000686E00011.png"\; state="\{\{state\}\}">L</figure-callout>}}_2={\&Integral;}_0^{t}v\cos \frac{\mathrm{\&theta;}}{2}\mathrm{dt}=\frac{{\mathrm{\&lambda;}}_2}{2}{\&Integral;}_0^t\mathrm{\&Delta;}{\mathrm{<figure-callout\; id="2"\; label="f"\; filenames="H2009101000686E00011.png"\; state="\{\{state\}\}">f</figure-callout>}}_2\mathrm{dt}$

The optical path difference of two light paths is:

ΔL＝L ₂-L ₁

According to geometric relationship shown in Figure 2, the linearity value that can obtain measurand is:

$\mathrm{\&Delta;h}=\frac{\frac{\mathrm{\&Delta;<figure-callout\; id="2"\; label="L"\; filenames="H2009101000686E00011.png"\; state="\{\{state\}\}">L</figure-callout>}}{2}}{\sin \frac{\mathrm{\&theta;}}{2}}=\frac{L_2-{\mathrm{<figure-callout\; id="1"\; label="L"\; filenames="H2009101000686E00011.png"\; state="\{\{state\}\}">L</figure-callout>}}_1}{2\sin \frac{\mathrm{\&theta;}}{2}}---\left(1\right)$

In the formula: when Δ h when negative, measure catoptron 7 and upwards depart from datum axis; When Δ h is timing, measure catoptron 7 downward biases from datum axis.

The pairing position of this linearity is:

$S=\frac{{\mathrm{<figure-callout\; id="1"\; label="L"\; filenames="H2009101000686E00011.png"\; state="\{\{state\}\}">L</figure-callout>}}_1+\frac{\mathrm{\&Delta;<figure-callout\; id="2"\; label="L"\; filenames="H2009101000686E00011.png"\; state="\{\{state\}\}">L</figure-callout>}}{2}}{\cos \frac{\mathrm{\&theta;}}{2}}=\frac{{\mathrm{<figure-callout\; id="1"\; label="L"\; filenames="H2009101000686E00011.png"\; state="\{\{state\}\}">L</figure-callout>}}_1+{\mathrm{<figure-callout\; id="2"\; label="L"\; filenames="H2009101000686E00011.png"\; state="\{\{state\}\}">L</figure-callout>}}_2}{2\cos \frac{\mathrm{\&theta;}}{2}}---\left(2\right)$

In summary, can obtain the linearity and the position thereof of measurand by formula (1) and formula (2).

As shown in Figure 2, dotted line is not represented to measure when catoptron produces the linearity deviation and is positioned on the datum axis.

Claims (1)

1. one kind based on the linearity of double frequency principle of interference and the measurement mechanism of position thereof, it is characterized in that: light source is that the laser beam that transverse zeeman effect He-Ne two-frequency laser (1) sends is divided into two bundles through common spectroscope (2), first folded light beam is incident to first analyzer (3), because shake the thoroughly direction and the pairwise orthogonal linearly polarized light angle at 45 of analyzer, the linearly polarized light of pairwise orthogonal is decomposed on the same direction of shaking, form beat frequency, received conduct with reference to signal by first photodetector (4), its frequency is f ₁-f ₂, first transmitted light beam is divided into second folded light beam and second transmitted light beam once more through depolarization Amici prism (5), second folded light beam incides polarization splitting prism (8), second transmitted light beam after wollaston prism (6) transmission with f ₁And f ₂The light of two frequencies is divided into the two-way measuring beam, and the measurement catoptron (7) that directive is made up of right-angle prism is measured catoptron and is positioned on the measurand (13), measures catoptron and when mobile, produce and contain Doppler frequency difference ± Δ f on measurand ₁With ± Δ f ₂Two measuring beam f ₁± Δ f ₁And f ₂± Δ f ₂, another point to wollaston prism (6) after measuring catoptron (7) reflection merges into a branch of light, sees through wollaston prism (6) back directive polarization splitting prism (8) once more, and wherein, frequency is f ₁± Δ f ₁Transmittance polarization splitting prism (8) and second folded light beam in be f through the frequency of polarization splitting prism (8) reflection ₂Light form first via measuring beam, frequency is f ₂± Δ f ₂Light frequency through polarization splitting prism (8) transmission in polarization splitting prism (8) the reflection back and second folded light beam be f ₁Light form the second drive test amount light beam; First via measuring beam is incident to second analyzer (9), the pairwise orthogonal linearly polarized light angle at 45 of shake the thoroughly direction and the first via measuring beam of analyzer, the linearly polarized light of pairwise orthogonal is decomposed on the same direction of shaking, form beat frequency, received formation first via measuring-signal by second photodetector (10), its frequency is f ₁-f ₂± Δ f ₁Second drive test amount light beam incident the 3rd analyzer (11), the pairwise orthogonal linearly polarized light angle at 45 of shake the thoroughly direction and the second drive test amount light beam of analyzer, the linearly polarized light of pairwise orthogonal is decomposed on the same direction of shaking, form beat frequency, received the formation second drive test amount signal by the 3rd photodetector (12), its frequency is f ₁-f ₂± Δ f ₂, first via measuring-signal, the second drive test amount signal and reference signal process and display linearity that obtains measuring and position thereof through follow-up data acquisition and machine calculation machine; Be implemented as follows:

During measurement, establishing and measure catoptron (7) and move to measured position 2 by initial position 1, is v along the speed of measuring basis axis direction, can get according to Doppler effect:

In the formula: f ₁, f ₂Be two frequencies of two-frequency laser output orthogonal linearly polarized light, f ₁', f ₂' for containing two frequencies of Doppler frequency difference, c is a light speed in a vacuum, θ is the beam splitting angle of wollaston prism;

Speed is that v just gets when measuring catoptron (7) with the laser instrument move toward one another, and to be that v gets negative for speed during opposing motion, the measuring beam f that is caused by Doppler effect ₁And f ₂Frequency change be:

In the formula: λ ₁, λ ₂Be the optical maser wavelength of two frequencies;

If measuring catoptron (7) displacement is that S, time are t, by reference signal, frequency is f ₁-f ₂With first via measuring-signal, frequency is f ₁-f ₂± Δ f ₁, ask difference frequency can get Δ f ₁, by reference signal, frequency is f ₁-f ₂With the second drive test amount signal, frequency is f ₁-f ₂Δ f ₂, ask difference frequency can get Δ f ₂, the light path of Dui Ying two light paths then, i.e. displacement is changed to:

The optical path difference of two light paths is:

ΔL＝L ₂-L ₁

According to geometric relationship, the linearity value that can obtain measurand is:

In the formula: when Δ h when negative, measure catoptron (7) and upwards depart from datum axis; When Δ h is timing, measure catoptron 7 downward biases from datum axis;

The pairing position of this linearity is:

In summary, promptly obtain the linearity and the position thereof of measurand by formula (1) and formula (2).

Images