CN1285883C - Method and equipment for measuring rolling angle - Google Patents

Abstract

The present invention discloses a method and a device for measuring a rolling angle, which belongs to the technical field if photoelectric detection. The present invention is characterized in that a semiconductor laser is collimated by a single-mode optical fiber (2) and expanded by a collimating lens (3); a quarter wave plate (7) and a reflector (8) are orderly arranged on a light axis after the semiconductor laser passes through a polarization sheet (4); light rays penetrate through the quarter wave plate twice by the reflector and are transmitted to a multi-quadrant detector (6) by a Wollaston prism (5) to generate the difference value of voltage; the value of the rolling angle is obtained by detecting the difference value. Compared with the prior art, the present invention has the advantages of simple structure of the light path and convenient field measurement, and furthermore, the measurement sensitivity is enhanced, a mobile part is not with cables, and the cost is effectively reduced under the premise for ensuring the measurement accuracy.

Description

A kind of roll angle measurement method and device

Technical field

The invention belongs to photoelectric detection technology field, particularly a kind of non-contact measurement roll angle method and measurement mechanism.

Background technology

Machinery guide rail movement pair all has three revolution degree of freedom or is claiming angular motion error (pitching, beat and roll error).If instrument and lathe have the Abbe arm on the corresponding direction of these angular movement errors, these angular movement errors will cause Abbe error and influence their processing or measuring accuracy.At present, reduce or eliminate Abbe error and mainly dwindle the Abbe arm, improve guide rail movement precision and error correction by the suggestion of Lay grace not from structure, and the influence that reduces or eliminate Abbe error by the Ai Pengsitan principle from structure.Because the restriction of physical construction and physical dimension, nearly all three coordinate measuring machine and lathe all have the Abbe arm.Therefore accurate these angular motion errors of measurement are very important for the accuracy assessment and the error correction of instrument and lathe.Adopt the lathe or the three coordinate measuring machine of rectangular coordinate system to have 21 structural failures, wherein 18 errors can be with ready-made interferometer measurement, and other 3 roll angle errors are the most difficult measurements.In addition in the Installation And Calibration of some workpiece, also need roll angle is measured or located.

Measure for guide rail rolling angle, following four kinds of method of optics are arranged: 1. laser alignment method, John C.Tsai has proposed a kind of measuring method of utilizing double-collimation laser beam, U.S. Patent number is: 6316779B1, patent name is: Rotation and translation measurementwith phase sensitive detection.The method calculates the roll angle error by surveying the variation of two diverse locations with respect to parallel laser light position, and shortcoming is rolling angle measurement and other each parameter correlations, and the collimation of light beam be cannot say for sure to demonstrate,prove.2. interference technique, 1991, Chaney has proposed a kind of method of interfering of using fully and has measured roll angle " Optical apparatus for use with interferormetricmeasuring device " U.S. Patent number: 5056921, can obtain very high measuring accuracy, but measuring system need be installed a same long plane of reflection mirror with guide rail, difficult in practice the application.Another kind of interferometric method is based on the double-frequency laser interference method, and advantage is the precision height, and antijamming capability is strong.But need the linearity of two diverse locations of step measurement to calculate the roll angle size, can not be used for real-time measurement, using wastes time and energy.3. laser hologram diffraction approach, though can realize rolling angle measurement, and method is simple, and required optical device is few, and measuring accuracy is not high, and measuring head has cable to connect.4. laser polarization mensuration, this is the more a kind of method of research at present.The Jiang Hong of Tsing-Hua University, Yin Chunyong etc. are at article " Sensitivity enhanced roll angle measurement. " (Optical Engineering, 2000,39 (2): proposed a kind of non-linear roll angle measurement method 516～519) based on transverse zeeman laser, adopt quarter-wave plate that the double frequency linearly polarized laser of zeeman laser is become elliptically polarized light, polaroid is as Sensitive Apparatus, change to obtain the roll angle size by detected phase, can improve tens of times measuring sensitivity.Calendar year 2001, it is 01130893.1 that Yin Chun waits in China Patent No. forever, patent name is to propose in roll angle measurement method and the rolling angle measurement instrument thereof after the double frequency linearly polarized laser that adopts quarter-wave plate with zeeman laser becomes elliptically polarized light, adopted one 1/2nd wave plate as Sensitive Apparatus, adopt right angle reflector to make light path pass through 1/2nd wave plates twice simultaneously, obtain 4 times error angle at receiving position, together with non-linear humidification, can obtain 200 times sensitivity multiplication in theory, but this method also is to measure the size of roll angle by the method for detected phase.Though above-mentioned two kinds of method angle resolutions are greatly enhanced, cost is very expensive, and control circuit is very complicated.Zhang Enyao in 2002 etc. are 02123642.9 in China Patent No., patent name be a kind of based on orthogonal double polarizing light the roll angle photoelectric detecting method and the patent of device in a kind of roll angle photoelectric detecting method and device based on orthogonal double polarizing light disclosed, mainly be to utilize the brilliant light valve of timesharing modulation biliquid or two semiconductor laser timesharing to produce the pairwise orthogonal linearly polarized light, utilize polaroid as roll angle error Sensitive Apparatus, the light intensity that the roll angle error is converted to emergent light changes, by calculating the roll angle error.Though fairly simple on light path, measure sensitivity be better than 2 ", need the brilliant light valve of biliquid or two semiconductor lasers.In order to overcome this shortcoming, Tsing-Hua University proposed to utilize timesharing modulation magnetite garnet once more in 2005, made outgoing polarized light timesharing deflection ± π/4, thereby had substituted the brilliant light valve of biliquid or two semiconductor lasers, had improved measurement range and measuring accuracy.But measuring system still will adopt the timesharing modulation circuit, and magnetite garnet itself is just relatively more expensive, and measures the slip-on head tape cable, is inconvenient to be applied to in-site measurement.(《compact?optical?roll-angle?sensor?with?large?measurement?range?and?high?sensitivity》Optics?letters，2005，30(3)：242-244)。

Summary of the invention

The objective of the invention is guaranteeing to have proposed a kind of laser polarization roll angle photoelectric detecting method and device of based semiconductor single-mode fiber assembly under the precondition of measuring accuracy, on angle resolution, reach and be better than 1 ".Light channel structure is simple, thereby has reduced cost, simultaneously with the close light source of measuring light detector, makes and measures not tape cable of slip-on head, can make structure become more compact, is easy to apply.

A kind of roll angle measurement method that the present invention proposes may further comprise the steps:

1) laser that is sent by semiconductor laser expands bundle through single-mode fiber collimation, collimation lens, makes laser become linearly polarized light through polaroid again;

2) this linearly polarized light is through quarter-wave plate;

3) make through catoptron that light is reverse to be returned, pass through quarter-wave plate once more;

4) this light is divided into two-beam through wollaston prism;

5) survey two beam splitting light with a detector at last, light intensity is converted into electric signal, and this electric signal is sent into computing machine after amplifying computing through signal processing circuit, obtains the positive and negative reflection roll angle of magnitude of voltage direction, the value of its absolute value of voltage size reflection roll angle.

The present invention proposes to adopt the roll angle photoelectric detection system of said method, and this device comprises semiconductor laser, single-mode fiber, collimation lens, polaroid, quarter-wave plate, catoptron, wollaston prism, detector, driving and signal processing circuit and computing machine.Described single-mode fiber exit end is placed on the focus of collimation lens; Described quarter-wave plate fast axis direction becomes-π/4 with the collimation direction of polarized light; Described catoptron is placed on the other end of measuring guide rail and makes the reverse quarter-wave plate that passes through once more of light; Described wollaston prism is placed on the Laser emission end, and its optical axis direction becomes π/4 with the polarization laser direction; After described detector is placed on wollaston prism, and make two luminous points be incident upon the different quadrant of detector respectively.This detector links to each other with the roll angle signal processing circuit, sends into computing machine again after amplifying computing.

Beneficial effect of the present invention:

The present invention adopts semiconductor laser can reduce the volume of measuring system greatly.Adopt catoptron to make that light path is reverse to be returned, twice by roll angle Sensitive Apparatus quarter-wave plate, the sensitivity that has improved rolling angle measurement, make measure sensitivity can be superior in 1 ".Utilize a wollaston prism beam splitting simultaneously, only receive two beam splitting light, avoid using a plurality of detectors, make simple in structure, compact to the complicacy that system brings the sum of errors system with quadrant detector more than.Adopt catoptron to make reverse the returning of light path detector and light source be coexisted measure guide rail one end, measure not tape cable of movable part thereby make in addition, compact conformation makes things convenient for in-site measurement.

Description of drawings

Fig. 1 is the synoptic diagram of rolling angle measurement apparatus structure of the present invention.

Among the figure: semiconductor laser 1 single-mode fiber 2 collimation lenses 3 polaroids 4 wollaston prisms 5 detectors 6 quarter-wave plates 7 catoptrons 8 signal processing circuits 9 computing machines 10,101 and 103 is fixed cells of measurement mechanism, the 102nd, and the mobile unit of measurement mechanism.

Embodiment

Below in conjunction with accompanying drawing the present invention is further described.

Roll angle measurement method of the present invention is realized according to following principle:

Suppose that through the laser amplitude behind the collimation be A _x, A _y, circular frequency is ω, initial phase is δ _x, δ _y, then the electric vector of shoot laser is:

$E_0(z,t)=e^{i(\mathrm{ax}-2\mathrm{\πz}/\mathrm{\λ})}\left[\begin{array}{c}{A}_x{e}^{{\mathrm{i\δ}}_x}\\ A_y{e}^{{\mathrm{i\δ}}_y}\end{array}\right]=e^{i(\mathrm{ax}-2\mathrm{\πz}/\mathrm{\λ})}\left[\begin{array}{c}{E}_{x0}\\ E_{y0}\end{array}\right]---\left(1\right)$

Then being write as the Jones vector matrix form is: $E_0=\left[\begin{array}{c}{E}_{x0}\\ E_{y0}\end{array}\right]---\left(2\right)$

And the Jones matrix of the polarizer 4 is: $M_p=\left[\begin{array}{cc}0& 0\\ 0& 1\end{array}\right]---\left(3\right)$

Then be through the polarized light behind the polarizer 4:

$E_0^{\′}=M_p{E}_0=\left[\begin{array}{cc}0& 0\\ 0& 1\end{array}\right]\left[\begin{array}{c}{E}_{x0}\\ E_{y0}\end{array}\right]=\left[\begin{array}{c}0\\ E_{y0}\end{array}\right]---\left(4\right)$

The Jones matrix of quarter-wave plate 7 is:

$M(\mathrm{\λ}/4,\mathrm{\θ})=\left[\begin{array}{cc}{e}^{\mathrm{i\π}/4}{\cos }^2\mathrm{\θ}+e^{-\mathrm{i\π}/4}{\sin }^2\mathrm{\θ}& \sqrt{2}i\sin \mathrm{\θ}\cos \mathrm{\θ}\\ \sqrt{2}i\sin \mathrm{\θ}\cos \mathrm{\θ}& e^{-\mathrm{i\π}/4}{\cos }^2\mathrm{\θ}+e^{\mathrm{i\π}/4}{\sin }^2\mathrm{\θ}\end{array}\right]---\left(5\right)$

If fast axle becomes with laser polarization direction-π/4 angles during quarter-wave plate 7 beginnings, then following formula can be written as:

$M(\mathrm{\λ}/4,-\mathrm{\π}/4)=\frac{\sqrt{2}}{2}\left[\begin{array}{cc}1& -i\\ -i& 1\end{array}\right]---\left(6\right)$

As senser element, when the guide rail movement pair has roll angle Δ θ, and consider that Δ θ is that a low-angle then can be got by formula (5) with quarter-wave plate 7

$M(\mathrm{\λ}/4,-\mathrm{\π}/4+\mathrm{\Δ\θ})=\frac{\sqrt{2}}{2}\left[\begin{array}{cc}1+i2\mathrm{\Δ\θ}& -i\\ -i& 1-i2\mathrm{\Δ\θ}\end{array}\right]---\left(7\right)$

Light is reverse once more when the quarter-wave plate 7, and Jones matrix is:

$M(\mathrm{\λ}/4,\mathrm{\π}/4-\mathrm{\Δ\θ})=\frac{\sqrt{2}}{2}\left[\begin{array}{cc}1+i2\mathrm{\Δ\θ}& i\\ i& 1-i2\mathrm{\Δ\θ}\end{array}\right]---\left(8\right)$

The reflection matrix of catoptron is:

$M\left(R\right)=\left[\begin{array}{cc}-1& 0\\ 0& -1\end{array}\right]---\left(9\right)$

Because rotation matrix is:

When the wollaston prism optical axis became π/4 to place with the outgoing polarized light, then the Wollaston Jones matrix was:

$M_w=\left[\begin{array}{cc}\cos \mathrm{\π}/4& \sin \mathrm{\π}/4\\ -\sin \mathrm{\π}/4& \cos \mathrm{\π}/4\end{array}\right]=\frac{\sqrt{2}}{2}\left[\begin{array}{cc}1& 1\\ -1& 1\end{array}\right]---\left(11\right)$

Then according to accompanying drawing 1, laser by the Jones matrix of above-mentioned device is successively:

J(Δθ)＝M _w·M(λ/4，π/4-Δθ)·M(R)·M(λ/4，-π/4+Δθ)·E ₀′ (12)

Promptly $J\left(\mathrm{\Δ\θ}\right)=-\frac{\sqrt{2}}{2}{E}_{y0}\left[\begin{array}{c}1+2\mathrm{\Δ\θ}-i2\mathrm{\Δ\θ}\\ 1-2\mathrm{\Δ\θ}-i2\mathrm{\Δ\θ}\end{array}\right]---\left(13\right)$

Be to obtain two light beam light intensity difference on the detector 6 to be

$\mathrm{\ΔI}=\left(4\mathrm{\Δ\θ}\right)E_{y0}^2=4\mathrm{I\Δ\θ}---\left(14\right)$

Both Δ θ=Δ I/4I (15)

Luminous power at laser instrument is constant, i.e. I ₀Under the controlled condition, two quadrants obtain light intensity difference Δ I and roll angle Δ θ is linear on the detector 6.The voltage signal difference that obtains from detector 6 is sent into computing machine 10 after amplifying computings through signal processing circuit 9, just can obtain the roll angle size.

A kind of method of measuring roll angle of the present invention is to send laser by semiconductor laser 1, wherein the driving circuit of laser instrument can be independently, also driving circuit can be integrated in the signal processing circuit 9, laser expands bundle through single-mode fiber 2 collimations, collimation lens 3, makes laser become linearly polarized light through polaroid 4 again.Adopt quarter-wave plate 7 as the roll angle Sensitive Apparatus, and the quick shaft direction of quarter-wave plate 7 is become-π/4 with the linearly polarized laser direction, make through catoptron 8 that light path is reverse to be returned, can make the corner multiplication of laser polarizing face through quarter-wave plate 7 twice.Be divided into two-beam through wollaston prism 5 again, and make wollaston prism 5 optical axis directions become π/4 with the emerging ray direction of polarized light.Make quarter-wave plate 7 along with the tested guide rail kinematic pair produces a roll angle like this, on detector 6, obtain 4 times error angle.Total system can be divided into three ingredients: the one, and the fixed cell of forming by semiconductor laser 1, single-mode fiber 2, collimation lens 3, polaroid 4, wollaston prism 5, detector 6, signal processing circuit 9 101, make it be fixed on an end of measuring guide rail, and link to each other with computing machine 10; The 2nd, quarter-wave plate 7 is placed in the mobile unit 102 and is fixed on the kinematic pair of guide rail; The 3rd, catoptron 8 is placed in the fixed cell 103 and is fixed in the other end of measuring guide rail.

The embodiment one of apparatus of the present invention: adopt semiconductor laser 1 to send laser, expand bundle through microscope 3 again, incide on the polarizer 4, make measuring light become linearly polarized light through single-mode fiber 2 collimations.The quick shaft direction of quarter-wave plate 7 becomes with laser polarization direction-π/4, the polarized light that the polarizer 4 produces sees through quarter-wave plate 7 and incides on the prism of corner cube 8, another mistake is to reflection, see through quarter-wave plate 7 once more, become π/4 to be beamed into two-beam through wollaston prism 5 optical axis directions with the emergent light polarization direction, incide quadrants different on the dual-quadrant detector 6, obtain the signal of voltage difference.Amplify computing through signal processing unit 9 again and send into the size that computing machine 10 obtains roll angle.The semiconductor laser that adopts frequency and power stability is the key that improves measuring accuracy.

The embodiment two of apparatus of the present invention: adopt semiconductor laser 1 to send laser, expand bundle through microscope 3 again, incide on the polarizer 4, make measuring light become linearly polarized light through single-mode fiber 2 collimations.The quick shaft direction of quarter-wave plate 7 becomes with laser polarization direction-π/4, the polarized light that the polarizer 4 produces sees through quarter-wave plate 7 and incides on the right-angle prism 8, another mistake is to reflection, see through quarter-wave plate 7 once more, become π/4 to be beamed into two-beam through wollaston prism 5 optical axis directions with the emergent light polarization direction, incide quadrants different on the dual-quadrant detector 6, obtain the signal of voltage difference.Amplify computing through signal processing unit 9 again and send into the size that computing machine 10 obtains roll angle.It forms present embodiment device and substitutes prism of corner cube except catoptron 8 utilizes right-angle prism, and other device is identical with embodiment one, realize equally Measurement Resolution reach and be better than 1 ", and cost is reduced.

The embodiment three of apparatus of the present invention: adopt semiconductor laser 1 to send laser, expand bundle through microscope 3 again, incide on the polarizer 4, make measuring light become linearly polarized light through single-mode fiber 2 collimations.The quick shaft direction of quarter-wave plate 7 becomes with laser polarization direction-π/4, the polarized light that the polarizer 4 produces sees through quarter-wave plate 7 and incides on the opal 8, another mistake is to reflection, see through quarter-wave plate 7 once more, become π/4 to be beamed into two-beam through wollaston prism 5 optical axis directions with the emergent light polarization direction, incide quadrants different on the dual-quadrant detector 6, obtain the signal of voltage difference.Amplify computing through signal processing unit 9 again and send into the size that computing machine 10 obtains roll angle.It forms present embodiment device and substitutes prism of corner cube except catoptron 8 utilizes opal, and other device is identical with embodiment one, realize equally Measurement Resolution reach and be better than 1 ", but the cost of opal is higher.

The embodiment four of apparatus of the present invention: adopt semiconductor laser 1 to send laser through polarization-maintaining single-mode fiber 2 collimations, expand bundle through microscope 3 again, see through quarter-wave plate 7, its quick shaft direction becomes with laser polarization direction-π/4, transmitted light incides on the prism of corner cube 8 another mistake to reflection, see through quarter-wave plate 7 once more, become π/4 to be beamed into two-beam through wollaston prism 5 optical axis directions with the emergent light polarization direction, incide quadrants different on the dual-quadrant detector 6, obtain the signal of voltage difference.Amplify computing through signal processing unit 9 again and send into the size that computing machine 10 obtains roll angle.Present embodiment is protected inclined to one side single-mode fiber with band and is substituted single-mode fiber 2, saves the polarizer 4 simultaneously, and other device is identical with embodiment one, realize equally Measurement Resolution reach and be better than 1 ", and make that optical device further reduces, the cost reduction.

Claims (6)

1. roll angle measurement method may further comprise the steps:

1) laser that is sent by semiconductor laser (1) collimates through single-mode fiber (2), and collimation lens (3) expands bundle, passes through polaroid (4) again and becomes linearly polarized light;

2) this linearly polarized light sees through quarter-wave plate (7), and wherein the fast axle of quarter-wave plate becomes with the polarization direction of laser-π/4 angles;

3) make through catoptron (8) that light is reverse to be returned, see through quarter-wave plate (7) once more;

4) this light is beamed into two-beam through wollaston prism (5), and wherein the wollaston prism optical axis becomes π/4 angles with polarization laser;

5) survey two beam splitting light with a detector (6), light intensity is converted into electric signal, this electric signal is sent into computing machine (10) after amplifying computing through signal processing circuit (9), the positive and negative reflection roll angle direction of its output voltage, the value of absolute value of voltage size reflection roll angle.

2. rolling angle measurement device, comprise: semiconductor laser (1), single-mode fiber (2), collimation lens (3), polaroid (4), wollaston prism (5), detector (6), quarter-wave plate (7), catoptron (8), signal processing circuit (9) and computing machine (10), it is characterized in that the quick shaft direction of described quarter-wave plate (7) becomes-π/4 angles with the collimation direction of polarized light; Described wollaston prism (5) is placed on the Laser emission end, and its optical axis direction becomes π/4 angles with the polarization laser direction; After described detector (6) is placed on wollaston prism, and make two light beams be incident upon different quadrants respectively.

3. the described rolling angle measurement device of claim 2 is characterized in that, described collimation lens (3) is a microscope.

4. rolling angle measurement device as claimed in claim 2 is characterized in that, described detector (6) is dual-quadrant detector or 4 quadrant detector.

5. rolling angle measurement device as claimed in claim 2 is characterized in that, described catoptron (8) is corner cube mirror or prism of corner cube or opal.

6. rolling angle measurement device as claimed in claim 2 is characterized in that, described single-mode fiber (2) adopts polarization-maintaining single-mode fiber to substitute, and saves described polaroid (4) simultaneously.