CN107228638B - The method and apparatus that five degree of freedom error based on beam drift compensation measures simultaneously - Google Patents

Abstract

The invention proposes a kind of method and apparatus that the five degree of freedom error based on beam drift compensation measures simultaneously, and the high-precision while measurement method measurement accuracy to solve existing guide rail five degree of freedom are low, measurement range is small, poor anti jamming capability problem；Collimation lens, prism assemblies, polarization splitting prism, quarter-wave plate are set between laser and the right-angle prism for being coated with beam splitting coating, realize the processing to incident light and reflected light, by the information of reflected light and transmitted light after 4 quadrant detector and Position-Sensitive Detector reception and measurement beam splitting, the measurement of pitch angle, deflection angle and rolling angle error, horizontal direction straightness error, vertical direction straightness error and light drift compensation is realized.The present invention utilizes dual-beam variate, realizes error separate, enhances anti-interference ability, few using optical device, light source power is low, low in cost；Optical texture is simple, easy to operate, and movable part can be convenient for in-site measurement without cable；Angle resolution is higher.

Description

Method and device for simultaneous measurement of five-degree-of-freedom errors based on beam drift compensation

technical field

The invention relates to the technical field of photoelectric detection, in particular to a method and device for simultaneous measurement of five-degree-of-freedom errors based on beam drift compensation, which can realize the measurement of roll angle errors that are particularly difficult to measure.

Background technique

Mechanical guide kinematic pairs include three linear errors: position error along the axial direction and two straightness errors perpendicular to the axial direction, and three angle errors rotating around the axis: pitch angle, yaw angle and roll angle. If instruments and machine tools have Abbe arms in the directions corresponding to these geometric motion errors, these geometric motion errors will cause Abbe errors and affect their machining or measurement accuracy. At present, the reduction or elimination of Abbe error mainly reduces the Abbe arm in structure, improves the motion accuracy and error correction of the guide rail according to Brain's suggestion, and reduces or eliminates the influence of Abbe error in structure according to Eppenstein's principle. Due to the limitations of mechanical structure and geometric size, almost all CMMs and machine tools have Abbe arms. Therefore, accurate measurement of these geometric motion errors is very important for the accuracy evaluation and error correction of instruments and machine tools. There are 21 geometric error parameters for machine tools or CMMs using a Cartesian coordinate system, of which 18 errors can be measured with off-the-shelf interferometers, including the three most difficult to measure roll angle errors.

There are the following optical methods for the high-precision measurement of the five degrees of freedom of the guide rail:

1. Measurement method based on diffraction technology, simultaneous measurement method of five degrees of freedom based on holographic lens [JBergin M T, Bartolotta C S. Multi-axis optical alignment system including A spatialfilter, US Patent No.: 3701602.1972], this method is simple and has few components , The cost is low, but the measurement of the roll angle has high requirements on the stability of the beam, and the measurement accuracy is not high. The five-degree-of-freedom simultaneous measurement method based on the plane diffraction grating [Miller J M, Barton R O. Multi-axis alignment apparatus, US Patent No.: 4804270.1989] has low measurement accuracy, and its mobile fixed unit is connected to the cable, which limits the convenience of measurement. Six-degree-of-freedom displacement measurement system using a diffraction grating proposed by Kim [Kim J A, Kim K C, Bae E W, et al. Six-degree-of-freedom displacement measurement system using a diffraction grating[J]. Review of Scientific Instruments, 2000 ] The measurement accuracy is low, and the diffracted light divergence leads to the measurement range of the system is only a few millimeters, which is not suitable for on-site measurement.

2. Based on the measurement method of laser interference and collimation, Bruce L. et al. proposed a simultaneous measurement system of five degrees of freedom based on 2 parallel lights [Thomas B L, Bass H M, Loftus L K, et al. Laser aligned five-axis position measurement device, US Patent No.: US5798828.1998.], the method has a simple system structure, and can achieve different measurement resolutions only by adjusting the distance between the detectors. However, it is difficult to adjust the parallelism of the two beams of light and the consistency of the light spot, which will cause measurement errors, and the moving fixed unit with cables is inconvenient for dynamic measurement of high-speed CNC machine tools. A five-degree-of-freedom or six-degree-of-freedom simultaneous measurement system proposed by Lau [Lau K C, Liu Y Q. Five-axis/six-axislaser measuring system: EP, US Patent No.: US6049377[P].2000], the system measures It is the only commercial multi-degree-of-freedom simultaneous measurement system in the world with high precision. However, the mobile unit of the system is connected with cables, which is not suitable for high-speed and long-distance measurement in the field. At the same time, the roll angle measurement of this system also requires an electronic level, which cannot be used in The measurement of the roll angle of the vertical axis is expensive. A method of simultaneous measurement of six degrees of freedom proposed by Liu [Liu C H, Jywe WY, Hsu C C, et al. Development of a laser-based high-precision six-degrees-of-freedom motion errors measuring system for linear stage[J ]. Review of Scientific Instruments, 2005] and a five-degree-of-freedom simultaneous measurement method proposed by Kuang C et al. [Kuang C, Hong E, Ni J. A high-precision five-degree-of-freedom measurement system based on laser collimator and interferometry techniques[ J]. Review of Scientific Instruments, 2007] and a method of simultaneous measurement of five degrees of freedom proposed by Huang P et al [Huang P, Li Y, Wei H, et al. Five-degrees-of-freedom measurement system based on a monolithic Prism and phase-sensitive detection technique.[J].AppliedOptics,2013], these methods are also based on the combination of laser interference and laser collimation, which have high measurement accuracy, high integration, and large measurement range, but the measurement system volume The continuous heating of the light source will cause many problems such as laser drift and poor anti-interference ability.

3. Based on the measurement method of laser grating interference, Liu C H et al. proposed a simultaneous measurement method of five degrees of freedom [Liu C H, Huang H L, Lee H W.Five-degrees-of-freedom diffractive laserencoder.[J].Applied Optics, 2009] and a simple six-degree-of-freedom simultaneous measurement method proposed by Lee [LeeC B, Kim G H, Lee S K. Design and construction of a single unit multi-function optical encoder for a six-degree-of-freedom motion Error measurement in an ultraprecision linear stage [J]. Measurement Science & Technology, 2011], the above methods are all based on laser grating interference technology, the measurement principle and system structure are relatively simple, but the size of the precision diffraction grating is limited, so the measurement range is small.

SUMMARY OF THE INVENTION

Aiming at the problems of low measurement accuracy, small measurement range, and poor anti-interference ability of the existing high-precision measurement method with five degrees of freedom of guide rails, the present invention provides a method and device for simultaneous measurement of five-degree-of-freedom errors based on beam drift compensation. Optical structure It is simple and compact, easy to operate, and has good accuracy, stability and economy.

In order to solve the above-mentioned technical problems, the technical scheme of the present invention is: a method for simultaneous measurement of errors of five degrees of freedom based on beam drift compensation, the steps of which are as follows:

Step 1: The laser emits laser light, which is collimated by the collimating lens and then exits; after the beam collimated by the collimating lens exits through the beam splitter prism, the beam passes through the isolator, the polarization beam splitter prism, and the quarter-wave plate and is incident on the test center. The hypotenuse surface of the right-angle prism coated with the beam splitter film on the platform;

Step 2: The reflected beam of the right-angle prism coated with the beam splitting film returns. After passing through the quarter-wave plate, the polarization direction of the beam changes, and then the beam splitting by the polarizing beam splitting prism is sensitively detected by the position located at the focal plane of the focusing lens. When the platform to be tested is pitched and yawed, the focused spot position of the reflected beam on the position-sensitive detector changes, and the photoelectric signal output by the position-sensitive detector passes through the signal processing circuit and is sent to the processing terminal to obtain the Measurement of pitch angle and yaw angle error to be measured for laser light drift error;

Step 3: The transmitted beam after beam splitting enters the right angle prism coated with the beam splitter film, is refracted by the right angle side of the right angle prism coated with the beam splitter film, and then exits after being split by the beam splitter and then reaches the four-quadrant detector. When the straightness error is to be measured, the spot position of the transmitted beam on the four-quadrant detector changes, and the photoelectric signal output by the four-quadrant detector passes through the signal processing circuit, and then is sent to the processing terminal to obtain the straight line in the horizontal direction to be measured including the laser light drift. degree error value;

Step 4: The reflected beam of the right-angle prism coated with the beam splitter film and the transmitted beam emitted after entering the right-angle prism coated with the beam splitter film are split by different beam splitters, and received by two different four-quadrant detectors. For the split beam, roll angle measurement is realized after differential operation;

Step 5: The reflected beam of the right-angle prism coated with the beam splitter film and the transmitted beam emitted after entering the right-angle prism coated with the beam splitter film are split by different beam splitters, and the beams reach the focal points of the two focusing lenses respectively. Two position-sensitive detectors on the plane are used for receiving and processing, and the optical drift amount is obtained after differential operation to realize optical drift compensation;

Step 6: Rotate the right angle prism coated with the beam splitter film by 90 degrees, the laser emits laser light, which is collimated by the collimating lens and then exits. The outgoing beam is translated upward through the beam splitter prism and the right angle prism. The prism and the quarter-wave plate are incident on the hypotenuse of the right-angle prism coated with the beam splitter film on the test platform. After reflection by the beam splitting prism and transmission by the beam splitter, it reaches the four-quadrant detector and is received and processed to realize the measurement of the straightness error in the vertical direction.

The method for measuring the straightness error in the horizontal direction is: when the right angle prism coated with the beam splitter film moves along the measuring guide rail, the straightness error Δx of the measured guide rail will cause the right angle prism coated with the beam splitter film to have a corresponding displacement Δx. , according to the characteristics of the right angle prism, the spot displacement of the collimated beam transmitted and returned on the four-quadrant detector is 2Δx.

In the step 6, the beam returned after being transmitted by the right-angle prism coated with the beam splitter film contains vertical straightness information. When the right-angle prism coated with the beam splitter film moves along the measuring guide rail, the straightness error Δy of the measured guide rail is The right angle prism coated with the beam splitter film will have a corresponding displacement Δy; according to the characteristics of the right angle prism, the collimated beam transmitted and returned by the right angle prism coated with the beam splitter film is then passed through a quarter wave plate, a polarized beam splitter prism, a The beamer is received by the four-quadrant detector, and the displacement of the light spot generated on the four-quadrant detector is 2Δy, which realizes the measurement of vertical straightness.

A device for simultaneous measurement of five-degree-of-freedom errors based on beam drift compensation, comprising a fixed unit and a moving unit, the moving unit is fixed on a test platform; the moving unit includes a right-angle prism coated with a beam splitting film, which is coated with a beam splitting film The right-angle prism is fixed on the measuring platform moving along the guide rail; the fixed unit includes a laser, a collimating lens, a prism assembly, a polarizing beam splitter prism, a quarter-wave plate, an isolator, a beam splitter, and a four-quadrant detector. , position sensitive detector, focusing lens and signal processing circuit, collimating lens, prism assembly, isolator, polarizing beam splitter prism and quarter wave plate are arranged in sequence between the laser and the right angle prism coated with beam splitter film above; the beam splitter includes beam splitter I and beam splitter II, the four-quadrant detector includes four-quadrant detector I and four-quadrant detector II, and the position-sensitive detector includes position-sensitive detector I and position-sensitive detector II, the focusing lens includes a focusing lens I and a focusing lens II, the beam splitter I and the focusing lens I are sequentially arranged on the light of the transmitted beam of the right-angle prism coated with the beam splitting film, and the position-sensitive detector I is arranged on the focusing lens I. On the focal plane, the four-quadrant detector II is set on the optical path of the beam splitter I; the beam splitter II and the four-quadrant detector I are set on the optical path of the polarizing beam splitter prism, and the focusing lens II and the position sensitive detector II are set on the splitter. On the optical path of the beamer II, the position-sensitive detector II is arranged on the focal plane of the focusing lens II; the position-sensitive detector I, the position-sensitive detector II, the four-quadrant detector I and the four-quadrant detector II are all related to the signal The processing circuit is connected, and the signal processing circuit is connected with the processing terminal.

The right-angle prism coated with the beam splitting film is fixed on a rotating device that can rotate 90 degrees, and the rotating device is fixed on the measuring platform.

The prism assembly includes a dichroic prism and a right angle prism, and the right angle prism is arranged above the dichroic prism.

The laser is a He-Ne laser or a semiconductor laser; the collimating lens is a single lens or a lens group.

In the invention, a collimating lens, a prism assembly, a polarizing beam splitting prism, and a quarter-wave plate are arranged between the laser and the right-angle prism coated with the beam splitting film, so as to realize the processing of the incident light and the reflected light. The position sensitive detector receives and measures the information of reflected light and transmitted light after beam splitting, and realizes the measurement of pitch angle, yaw angle and roll angle error, horizontal straightness error, vertical straightness error and optical drift compensation. The present invention adopts a right-angle prism coated with a beam splitting film as a sensitive device, utilizes double beam differential measurement, realizes error separation, and enhances anti-interference ability; uses a position-sensitive detector to realize optical drift compensation; uses a The right angle prism 90° fixed rotation device realizes the measurement of the straightness error in the vertical direction; it uses few optical components, the light source power is low, and the cost is low; the optical structure is simple and compact, easy to operate, and the moving part can be without cables, which is convenient for on-site measurement; angle measurement Resolutions up to 0.3" and beyond.

Description of drawings

In order to explain the embodiments of the present invention or the technical solutions in the prior art more clearly, the following briefly introduces the accompanying drawings that need to be used in the description of the embodiments or the prior art. Obviously, the accompanying drawings in the following description are only These are some embodiments of the present invention. For those of ordinary skill in the art, other drawings can also be obtained according to these drawings without creative efforts.

FIG. 1 is a schematic structural diagram of the present invention.

FIG. 2 is a schematic front view of the structure of the right angle prism of FIG. 1 rotated by 90 degrees according to the present invention.

FIG. 3 is an enlarged schematic partial front view of FIG. 2 of the present invention.

In the figure, 1 is a laser, 2 is a collimating lens, 3 is a prism assembly, 31 is a beam splitting prism, 32 is a right angle prism, 4 is a polarizing beam splitting prism, 5 is a quarter-wave plate, and 6 is a right angle with a beam splitter coating. Prism, 7 is beam splitter I, 8 is focusing lens I, 9 is position sensitive detector I, 10 is beam splitter II, 11 is four-quadrant detector I, 12 is four-quadrant detector II, 13 is focusing lens II, 14 is a position sensitive detector II, 15 is an isolator, 16 is a signal processing circuit, 17 is a computer, 101 is a fixed unit, and 102 is a mobile unit.

Detailed ways

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, but not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

As shown in Figure 1, a method for simultaneous measurement of five degrees of freedom errors based on beam drift compensation, the steps are as follows:

Step 1: The laser emits laser light, which is collimated by the collimating lens and then exits; after the beam collimated by the collimating lens exits through the beam splitter prism, the beam passes through the isolator, the polarization beam splitter prism, and the quarter-wave plate and is incident on the test center. The hypotenuse of the right-angle prism coated with the beam splitter film on the platform.

As shown in Figures 1 and 2, the right-angle prism 6 coated with the beam splitter film is fixed on the test platform and can move along the measured linear guide rail. The beam splitter film is only provided on the right angle prism 6 coated with the beam splitter film. On one side of the hypotenuse, the side of the right-angle prism 6 provided with the beam splitting film can divide the incident beam into two beams: a reflected beam and a transmitted beam. The laser light emitted by the laser 1 is collimated and emitted by the collimating lens 2, and then the beam is split by the beam splitter 31, the isolator 15 selects the beam that needs to be transmitted at this time, the polarized beam splitting prism 4 is emitted, and the quarter-wave plate 5 is vertical. Incident on the right-angle prism 6 coated with the beam splitter. The incident light beam entering the right-angle prism 6 coated with the beam splitter film will be split, and one beam is directly reflected by the hypotenuse surface of the right-angle prism 6 coated with the beam splitter film, including the pitch angle and yaw angle information; A beam enters the hypotenuse surface of the right angle prism 6 coated with the beam splitter film and transmits, and is refracted by the right angle side of the right angle prism 6 coated with the beam splitter film and then transmits from the hypotenuse surface. The beam is parallel to the incident light, and its Contains information on roll angle, pitch angle, horizontal straightness, and light drift caused by the environment.

Assuming that the direction vector of the incident light perpendicular to the right angle prism 6 coated with the beam splitter film is I ₀ =[0 0 -1] ^T , it can be known from the vector matrix method that when the measurement platform is initially stationary, after the beam splitter is coated The direction vectors of the beam after reflection and transmission of the right angle prism 6 of the film are respectively:

I ₁ =[0 0 1] ^T , (1),

I ₂ =[0 0 1] ^T , (2);

When the measurement platform moves, the right-angle prism 6 coated with the beam splitter film moves along with it. It is assumed that it has rotation angles of α, β, and γ around the x, y, and z axes, respectively, where α is the pitch angle and β is the yaw angle. , γ is the roll angle, and the positive or negative of the angle around the coordinate axis follows the right-hand rule. The rotation matrices of the right-angle prism 6 coated with the beam splitter film on the x, y, and z axes are:

When α, β, and γ are all small, the influence of the rotation order can be ignored. After ignoring the high-order small quantities, the rotation matrix of the right-angle prism 6 coated with the beam splitter film is:

Assuming that the normal direction vector of each reflecting surface of the right-angle prism 6 coated with the beam splitter film is N=[N _x , N _y , N _z ], its reflection matrix is:

After the measuring platform moves, there is ^NR = RN, then the reflected beam after reflection The direction vector is:

in, is the vector consisting of the first row in the reflection matrix M. After the incident light I ₀ enters the right-angle prism 6 coated with a beam splitter film with a refractive index of n, its direction vector is:

The direction vector after one reflection in the right-angle prism 6 coated with the beam splitter film is:

The direction vector after two reflections in the right-angle prism 6 coated with the beam splitter is:

The transmitted beam returned by the right-angle prism 6 coated with the beam splitter The direction vector is:

Step 2: After the reflected beam of the right angle prism 6 coated with the beam splitter film returns and passes through the quarter wave plate 5 and the polarized beam splitter prism 4, it is received by the position sensitive detector II 14 located at the focal plane of the focusing lens 13, which can realize the pitch angle and yaw angle error measurements.

After the reflected beam is returned by the quarter-wave plate 5 and the polarization beam splitter prism 4, it is refracted by the polarization beam splitter prism 4 and enters the beam splitter II10. The parallel light split by the beam splitter II10 passes through the focusing lens II8 and enters the position sensitive detector. II14 received.

The reflected beam of the beam splitter coated right-angle prism contains the pitch angle and yaw angle information. When the beam splitter coated right-angle prism moves along the measured guide rail, the pitch or yaw occurs, compare formulas (1) and (6) ), then the reflected beam will be deflected by twice its angle, and the image point focused on the position-sensitive detector by the focusing lens will be displaced accordingly, as follows:

d _y ≈2fα,d _x ≈2fβ, (11)

In the formula, f is the focal length of the lens, and d _x and _dy are the displacements of the image point in the x-axis and y-axis directions on the position-sensitive detector, respectively. After the photoelectric signal output by the position sensitive detector passes through the signal processing circuit, it is sent to the processing terminal to obtain the measurement of the pitch angle and yaw angle error to be measured including the laser light drift error. but:

α≈d _y /(2f), β≈d _x /(2f), (12)

The pitch angle and yaw angle can be measured by formula (12).

Step 3: The transmitted beam after beam splitting enters the right angle prism coated with the beam splitting film, is refracted by the right angle side of the right angle prism coated with the beam splitting film, and is split by the beam splitter to reach the four-quadrant detector and receive it. processing to realize the measurement of the straightness error in the horizontal direction.

The transmitted light returned by the right-angle prism 6 coated with the beam splitter film is split by the beam splitter I7, and the split vertical light reaches the four-quadrant detector II12. When the straightness error to be measured occurs, the spot position of the transmitted beam on the four-quadrant detector changes, and the photoelectric signal output by the four-quadrant detector passes through the signal processing circuit and then is sent to the processing terminal to obtain the measured level including the laser light drift. Orientation straightness error value.

When the right-angle prism coated with the beam splitter film moves along the measured guide rail, the straightness error Δx of the measured guide rail will cause the corresponding displacement Δx of the right-angle prism coated with the beam splitter film. The spot displacement of the collimated beam on the four-quadrant detector is 2Δx, and the horizontal straightness can be measured.

Step 4: The reflected beam of the right-angle prism coated with the beam splitter film and the transmitted beam emitted after entering the right-angle prism coated with the beam splitter film are split by different beam splitters, and received by two different four-quadrant detectors. After splitting the beam, the roll angle measurement is realized after differential operation.

The right-angle prism 6 coated with the beam splitter film transmits and emits the returned light beam, which includes the information of roll angle, pitch angle, horizontal straightness and light drift caused by the environment. Assuming that the length of the hypotenuse of the right-angle prism 6 coated with the beam splitter film is L, and the distance between the incident light I ₀ and the outgoing light I ₂ is d, it can be known from formulas (2) and (7) to (9) that the measurement platform Transmitted beam after moving When the right-angle prism 6 coated with the beam splitter film is emitted, the displacement in the y direction is:

Δy=d·γ-Lα/n; (13).

Suppose the initial distance from the right-angle prism 6 coated with the beam splitter film to the four-quadrant detector II12 on the transmitted beam is z ₀ , and the moving distance of the measuring platform along the z-axis is Δz. After the right-angle prism 6 with beam splitter moves with the measuring platform, it transmits the beam same reflected beam The change of the -2α pitch angle has also occurred, and the displacement in the y direction when it reaches the four-quadrant detector II12 is:

Δy ₁ =Δy+(z ₀ +Δz)(−2α)=dγ+Δy ₂ (14),

In the formula, Δy ₂ =(-2α)(z ₀ +Δz+L/2n) (15).

It can be known from equations (1) and (6) that Δy ₂ can be received by the four-quadrant detector I11 on the reflected beam at a distance of z ₀ +Δz + L/2n from the right-angle edge, 6 coated with the beam splitter film. to obtain, then: Implement roll angle measurement.

Step 5: The reflected beam of the right-angle prism coated with the beam splitter film and the transmitted beam emitted after entering the right-angle prism coated with the beam splitter film are split by different beam splitters, and the two beams arrive at the two focusing points respectively. The two position-sensitive detectors on the focal plane of the lens are received and processed, and the angular optical drift is obtained after differential operation, and then the measurement error caused by the angular optical drift is obtained based on the original error measurement values. And then realize optical drift compensation.

Step 6: Rotate the right angle prism coated with the beam splitter film by 90 degrees, the laser emits laser light, which is collimated by the collimating lens and then exits. The outgoing beam is translated upward through the beam splitter prism and the right angle prism. The prism and the quarter-wave plate are incident on the hypotenuse of the right-angle prism coated with the beam splitter film on the test platform. After reflection by the beam splitting prism and transmission by the beam splitter, it reaches the four-quadrant detector and is received and processed to realize the measurement of the straightness error in the vertical direction.

As shown in FIG. 3 , the spacer 15 is moved upward, and is provided on the rear side of the right angle prism 32 in the horizontal direction. After the laser light emitted by the laser 1 is collimated and emitted by the collimating lens 2, the light beam is vertically incident on the right angle prism 6 which is rotated by 90 degrees and coated with the beam splitter film through the prism assembly 3 and the quarter wave plate 5. The beam returned after being transmitted by the right-angle prism 6 coated with the beam splitter film contains vertical straightness information. When the right-angle prism 6 coated with the beam splitter film moves along the measuring guide rail, the straightness error Δy of the measured guide rail will cause the plating The right-angle prism 6 with the beam splitter is displaced accordingly by Δy. According to the characteristics of the right angle prism, the collimated beam transmitted and returned by the right angle prism 6 coated with the beam splitter film is then passed through the quarter wave plate 5, the polarizing beam splitter prism 4, and the beam splitter II10, and then received by the four-quadrant detector I11, The resulting spot displacement on the four-quadrant detector I11 is 2Δy, which enables vertical straightness measurement.

A device for simultaneous measurement of five-degree-of-freedom errors based on beam drift compensation, comprising a fixed unit 101 and a mobile unit 102, the mobile unit 102 is fixed on a test platform; the mobile unit 102 includes a right-angle prism 6 coated with a beam splitter film, The right-angle prism 6 coated with the beam splitter film is fixed on the measuring platform moving along the guide rail; the fixing unit 101 includes a laser 1, a collimating lens 2, a prism assembly 3, a polarizing beam splitting prism 4, and a quarter-wave plate 5 , isolator 15, beam splitter, four-quadrant detector, position sensitive detector, focusing lens and signal processing circuit 16, collimating lens 2, prism assembly 3, isolator 15, polarizing beam splitter prism 4 and quarter wave The sheet 5 is sequentially arranged on the light between the laser 1 and the right-angle prism 6 coated with the beam splitter film; the beam splitter includes the beam splitter I7 and the beam splitter II10, and the four-quadrant detector includes the four-quadrant detector I11 and The four-quadrant detector II12, the position sensitive detector includes the position sensitive detector I9 and the position sensitive detector II14, the focusing lens includes the focusing lens I8 and the focusing lens II13, the beam splitter I7 and the focusing lens I8 are sequentially arranged on the beam splitter coated with the beam splitter. On the light of the transmitted beam of the right angle prism 6, the position-sensitive detector I9 is set on the focal plane of the focusing lens I8, the four-quadrant detector II12 is set on the optical path of the beam splitter I7; the beam splitter II10 and the four-quadrant detector I11 is arranged on the optical path of the polarization beam splitter prism 4, the focusing lens II13 and the position sensitive detector II14 are arranged on the optical path of the beam splitter II10, and the position sensitive detector II14 is arranged on the focal plane of the focusing lens II13; The device I9, the position sensitive detector II14, the four-quadrant detector I11 and the four-quadrant detector II12 are all connected with the signal processing circuit 16, and the signal processing circuit 16 is connected with the computer 17.

Preferably, the right-angle prism 6 coated with the beam-splitting film is fixed on a rotating device capable of rotating 90 degrees, the rotating device is fixed on the measuring platform, and the rotating device can rotate the right-angle prism 6 coated with the beam-splitting film by 90 degrees. The prism assembly 3 includes a dichroic prism 31 and a right angle prism 32 , and the right angle prism 32 is arranged above the dichroic prism 31 . The laser 1 is a He-Ne laser or a semiconductor laser; the collimating lens 2 is a single lens or a lens group.

The above descriptions are only preferred embodiments of the present invention, and are not intended to limit the present invention. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the scope of the present invention. within the scope of protection.

Claims (7)

1. A method for simultaneously measuring five-degree-of-freedom errors based on beam drift compensation is characterized by comprising the following steps of:

the method comprises the following steps: the laser emits laser, and the laser is collimated by the collimating lens and then emitted; after the light beam collimated by the collimating lens is emitted through the beam splitter prism, the light beam is incident on the inclined edge surface of the right-angle prism which is positioned on the platform to be tested and plated with the beam splitting film through the isolator, the polarization beam splitter prism and the quarter-wave plate;

step two: the reflected light beam of the right-angle prism coated with the beam splitting film returns, the polarization direction of the light beam is changed after passing through the quarter-wave plate, then the light beam is reflected by the polarization beam splitting prism and then is received by a position sensitive detector positioned on the focal plane of the focusing lens, when the test platform is pitched and swung, the position of a focusing light spot of the reflected light beam on the position sensitive detector is changed, a photoelectric signal output by the position sensitive detector is sent to a processing terminal after passing through a signal processing circuit, and error measurement of a pitch angle to be measured and a swing angle to be measured, which contain laser beam drift errors, is obtained;

step three: the split transmitted light beam enters a right-angle prism coated with a beam splitting film, is reflected and emitted out through a right-angle side of the right-angle prism coated with the beam splitting film, is split by a beam splitter I and reaches a four-quadrant detector II, when a straightness error to be detected occurs, the position of a light spot of the transmitted light beam on the four-quadrant detector II is changed, and a photoelectric signal output by the four-quadrant detector II is sent to a processing terminal after passing through a signal processing circuit to obtain a straightness error value in the horizontal direction to be detected, wherein the straightness error value comprises laser light drift;

step four: the method comprises the following steps that a reflected beam of a right-angle prism plated with a beam splitting film and a transmitted beam emitted after entering the right-angle prism plated with the beam splitting film are split by a beam splitter I and a beam splitter II respectively, two different four-quadrant detectors I and II receive the split reflected beams respectively, and roll angle measurement is achieved after differential operation;

step five: the reflected light beams of the right-angle prism plated with the beam splitting film and the transmitted light beams emitted after entering the right-angle prism plated with the beam splitting film are respectively split by a beam splitter I and a beam splitter II, the transmitted light beams split by the beam splitter I and the beam splitter II respectively reach two position sensitive detectors positioned on focal planes of two focusing lenses and are received, and the light drift amount is obtained after differential operation, so that light drift compensation is realized;

step six: the right-angle prism coated with the beam splitting film is rotated by 90 degrees, the laser emits laser, the laser is collimated by the collimating lens and then is emitted, the emitted light beam is translated upwards through the beam splitting prism and the right-angle prism, the translated light beam is emitted onto the bevel edge surface of the right-angle prism coated with the beam splitting film on the test platform through the isolator, the polarization beam splitting prism and the quarter-wave plate, after being transmitted by the right-angle prism coated with the beam splitting film, the light beam is reflected by the quarter-wave plate and the polarization beam splitting prism, and after being transmitted by the beam splitter, the light beam reaches the four-quadrant detector I and is received and processed, and measurement of straightness errors in.

2. The method for measuring five-degree-of-freedom error simultaneously based on beam drift compensation as claimed in claim 1, wherein the method for measuring the horizontal direction straightness error is as follows: when the right-angle prism coated with the beam splitting film moves along the measured guide rail, the straightness error of the measured guide railWill make the right-angle prism plated with the beam splitting film generate corresponding displacementAccording to the characteristics of the right-angle prism, the spot displacement of the collimated light beam transmitted and returned by the right-angle prism on the four-quadrant detector II is 2。

3. The method for five-degree-of-freedom error simultaneous measurement based on beam drift compensation as claimed in claim 1, wherein the returned beam after transmission through the beam splitter coated rectangular prism in the sixth step includes vertical straightness information, and when the beam splitter coated rectangular prism moves along the measured guide rail, the straightness error of the measured guide rail is detectedWill make the right-angle prism plated with the beam splitting film generate corresponding displacement(ii) a According to the characteristics of the right-angle prism, the collimated light beams transmitted and returned by the right-angle prism coated with the beam splitting film pass through the right-angle prismA quarter-wave plate, a polarization beam splitter prism and a beam splitter, which are received by a four-quadrant detector I, and the displacement of the light spot generated on the four-quadrant detector I is 2And the vertical straightness measurement is realized.

4. A device for simultaneously measuring five-degree-of-freedom errors based on beam drift compensation is characterized by comprising a fixed unit (101) and a movable unit (102), wherein the movable unit (102) is fixed on a test platform; the mobile unit (102) comprises a right-angle prism (6) plated with a beam splitting film, and the right-angle prism (6) plated with the beam splitting film is fixed on a test platform moving along a guide rail; the fixed unit (101) comprises a laser (1), a collimating lens (2), a prism assembly (3), a polarization beam splitting prism (4), a quarter-wave plate (5), an isolator (15), a beam splitter, a four-quadrant detector, a position sensitive detector, a focusing lens and a signal processing circuit (16), wherein the collimating lens (2), the prism assembly (3), the isolator (15), the polarization beam splitting prism (4) and the quarter-wave plate (5) are sequentially arranged on a light ray between the laser (1) and the right-angle prism (6) plated with a beam splitting film; the beam splitter comprises a beam splitter I (7) and a beam splitter II (10), the four-quadrant detector comprises a four-quadrant detector I (11) and a four-quadrant detector II (12), the position sensitive detector comprises a position sensitive detector I (9) and a position sensitive detector II (14), the focusing lens comprises a focusing lens I (8) and a focusing lens II (13), the beam splitter I (7) and the focusing lens I (8) are sequentially arranged on a light ray of a transmitted light beam of the right-angle prism (6) plated with a beam splitting film, the position sensitive detector I (9) is arranged on a focal plane of the focusing lens I (8), and the four-quadrant detector II (12) is arranged on a reflected light path of the beam splitter I (7); the beam splitter II (10) and the four-quadrant detector I (11) are arranged on a reflection light path of the polarization beam splitter prism (4), the focusing lens II (13) and the position sensitive detector II (14) are arranged on the reflection light path of the beam splitter II (10), and the position sensitive detector II (14) is arranged on a focal plane of the focusing lens II (13); the position sensitive detector I (9), the position sensitive detector II (14), the four-quadrant detector I (11) and the four-quadrant detector II (12) are all connected with a signal processing circuit (16), and the signal processing circuit (16) is connected with a processing terminal (17).

5. The device for simultaneous measurement of five-degree-of-freedom errors based on beam drift compensation according to claim 4, wherein the beam splitting film coated right angle prism (6) is fixed on a rotating device capable of rotating 90 degrees, and the rotating device is fixed on a test platform.

6. The apparatus for simultaneous five-degree-of-freedom error measurement based on beam drift compensation according to claim 4, wherein the prism assembly (3) comprises a beam splitter prism (31) and a right angle prism (32), and the right angle prism (32) is arranged above the beam splitter prism (31).

7. The apparatus for five degree-of-freedom error simultaneous measurement based on beam drift compensation according to claim 4, characterized in that the laser (1) is a laser of a He-Ne laser or a semiconductor laser; the collimating lens (2) is a single lens or a lens group.