WO2018040531A1 - Angle measurement and calibration device and system for laser interferometer - Google Patents

Abstract

Provided is an angle measurement and calibration device and system of a laser interferometer. The angle measurement and calibration device of the laser interferometer comprises a laser head (1), an angular interferoscope (2), an angular reflector (3), an upper turntable tray (4), a lower turntable tray (5), and a turntable base (6). The angular interferoscope (2) is arranged between the laser head (1) and the angular reflector (3). The angular reflector (3) is arranged on the upper turntable tray (4). The upper turntable tray (4) is arranged above the lower turntable tray (5). The turntable base (6) is provided with a recess, and the lower turntable tray (5) is arranged on the turntable base (6) via the recess. The device has a precise structure and a small standard angle error, and can calibrate an initial zero angle by actively generating an angle of declination. The angle of declination can be actively generated by an angle grating (11) and a driving member (10), and the generated angle is relatively precise. Accordingly, an initial zero error and a constant of the angular reflector (3) can also be calibrated during the calibrating process, which simplifies the calibration procedure of the laser interferometer and improves the calibration efficiency.

Description

Angle measuring calibration device and system for laser interferometer Technical field

The present invention relates to an angle calibration apparatus, and more particularly to an angle measurement calibration apparatus for a laser interferometer, and to an angle measurement calibration system including an angle measurement calibration apparatus of the laser interferometer.

Background technique

When the laser interferometer measures the angle, the measuring optical path and principle are as shown in FIG. 1 and FIG. 2, and the laser light emitted by the laser head 1 is divided into two paths in the angle interferometer 2, respectively pointing to the two pyramids in the angle mirror 3. Prism; when the angle mirror 3 is rotated by an angle α as a whole, the optical path difference of the two beams reflected by the corner cube changes δ, and the measurement transfer function is: α=arcsin(δ/A).

In the measurement transfer function α=arcsin(δ/A), α=0 and δ=0 are the origin 0 of the function, which means that the angle mirror 3 must be adjusted when starting the measurement so that the incident laser is perpendicular to the angle mirror 3 The conical tip of the two corner cubes is the optical centerline of the angle mirror 3. This is difficult to achieve in actual operation. As shown in Fig. 3, due to the inaccurate installation of the instrument, the angle mirror 3 has a skew angle α0 at the beginning of the measurement, and the skew angle α0 is called the initial zero error, if the angle of the laser interferometer software system is at this time When the reading of mirror 3 is cleared, the system operates in the coordinate system of α = α ₀ , δ = δ ₀ (δ ₀ = arcsinα ₀ ) (0'). When measuring, the angle mirror 3 rotates by β angle (in the 0' coordinate system), and the calculated angle is β ₀ in the 0 coordinate system, and obviously β-β ₀ is the measurement error caused by the initial zero error α ₀ , As shown in Figure 3.

It is very difficult to eliminate the initial zero error of the angle mirror 3 at the production site, usually by adjusting the angle mirror 3 so that the surface reflected light coincides with the incident light. However, since the surface of the angle mirror 3 is generally coated with an anti-reflection film, the reflected light is extremely weak. In order to increase the intensity of the reflected light, a plane mirror may be attached to the surface of the angle mirror 3 so that the reflection surface and the angle mirror 3 are The optical center lines are parallel, and the direction of the angle mirror 3 is adjusted with reference to this surface. However, the optical center line of the angle mirror 3 is difficult to determine in practice. It is difficult to determine the zero error by this method, and ideally, it will cause measurement errors of at least several seconds.

In the measurement transfer function, the measurement angle is closely related to the constant A of the angle mirror 3. If the measurement transfer function is differentiated,

For example, the design value of A is 30mm, and the error caused by different dA is calculated at 10°: when dA=0.18mm, then da=216′′, the error is 0.6%; when dA=0.06mm, then da=72′′ The error is 0.2%; it is obvious that the dimensional error of the angle mirror 3 constant A directly affects the uncertainty of the laser interferometer angle measurement.

In actual measurement, the constant A of the angle mirror 3 is often calibrated using a self-calibrating turret, but the turret to be tested and the self-contained turret must be rotated at the same specific angle, or the calibration method is complicated, or the calculation formula and There are still errors in the data processing method, which can cause new human error. For example, in the patent number CN101236076A, there is an error in calculating the initial zero error and the constant A compensation factor of the angle mirror 3. The mirror rotates clockwise from the initial zero error point by θ, counterclockwise to φ, and the actual optical path. There is an error in the difference calculation that causes the entire calculation error, and the formula is calculated by it.

get

The formula for calculating the optical path difference is A sin θ=τA sinρ-τAsinα ₀ and -A sinφ=τA sinγ-τA sinα ₀ , the geometric meaning of the two equations does not match the physical process of the actual optical path change, and the optical path is actually rotated clockwise θ The change should be τA sin(α ₀ +θ)-τA sinα ₀ =Asinρ. When the φ angle is rotated counterclockwise, the optical path change should be τAsin(α ₀ -φ)-τAsinα ₀ =Asinγ, so its zero compensation angle and reflection The final result of the compensation factor of the mirror constant has some errors.

Therefore, the prior art has the following disadvantages: first, the calibration process is complicated, the data processing is troublesome, and the calibration precision is limited; second, the calibration calculation formula has errors, and the data processing error is large; third, the calibration system is designed. Standard angle, the size is difficult to ensure accuracy, due to mechanical tolerances, the pin or V-groove has a certain tolerance to ensure that the fixture can be embedded, but the angular error caused by this tolerance can not be ignored in the accurate measurement. The reference angle must also be measured multiple times to determine the average, and the accuracy is poor.

Summary of the invention

The technical problem to be solved by the present invention is to provide an angle measuring and calibrating device for a laser interferometer which has a simple structure, small standard angle error, and can improve calibration efficiency, and provides an angle of an angle measuring and calibrating device including the laser interferometer. Measuring calibration system.

In this regard, the present invention provides an angle measuring and calibrating apparatus for a laser interferometer, comprising: a laser head, an angle interference mirror, an angle mirror, a turntable upper disc, a turntable lower disc, and a turntable base, wherein the angle interferometer is disposed at the Between the laser head and the angle mirror, the angle mirror is disposed on the turntable upper disc, and the turntable upper disc is set The turret base is provided with a groove, and the turret lower plate is disposed on the turret base through a groove.

According to a further improvement of the present invention, the turret base is provided with a connecting member, and the turret base is fixed to the external turret to be tested by a connecting member.

A further improvement of the invention is that the connector comprises a bolt hole and/or a screw hole.

A further improvement of the present invention is to further include a rotating shaft and a driving member, the rotating shaft is fixedly disposed below the upper disc of the turntable, and the driving member is coupled to the rotating shaft.

A further improvement of the invention is that the drive member is a motor.

A further improvement of the present invention is that the drive member is fixedly disposed inside the lower tray of the turntable.

A further improvement of the present invention is that it further includes an angle grating disposed below the rotating shaft.

A further improvement of the invention resides in that a control system is also included, the control system being coupled to the angular grating and the drive member, respectively.

A further improvement of the present invention is to further include a wireless signal receiving device that is disposed inside the lower tray of the turntable.

The present invention also provides an angle measurement calibration system for a laser interferometer, comprising an angle measurement calibration device for a laser interferometer as described above, and including a data processing device, the data processing device being in communication with the laser head.

Compared with the prior art, the invention has the advantages that the structure is precise, the standard angle error is small, and the initial zero angle can be calibrated by actively generating a certain declination, and the declination can be actively generated by the angle grating and the driving member. The generated angle is more accurate; on this basis, the initial zero error and the constant of the angle mirror can be simultaneously calibrated during the calibration process, which simplifies the calibration procedure of the laser interferometer and improves the calibration efficiency.

DRAWINGS

1 is a schematic diagram of an angle measuring optical path of a laser interferometer in the prior art;

2 is a schematic diagram of an angle measuring principle of a laser interferometer in the prior art;

3 is a schematic diagram showing the principle of the initial zero error of the laser interferometer in the prior art;

4 is a schematic structural diagram of a system according to an embodiment of the present invention;

Figure 5 is a cross-sectional structural view of a turntable according to an embodiment of the present invention;

6 is a schematic diagram of an angle calibration principle of an angle mirror rotating counterclockwise in an embodiment of the present invention;

7 is a schematic diagram showing the principle of angle calibration of an angle mirror rotating clockwise in an embodiment of the present invention.

detailed description

The preferred embodiments of the present invention are further described in detail below with reference to the accompanying drawings.

As shown in FIG. 4 and FIG. 5, the present embodiment provides an angle measuring and calibrating apparatus for a laser interferometer, comprising: a laser head 1, an angle interference mirror 2, an angle mirror 3, a turntable upper disc 4, a turntable lower disc 5, and a turret base 6, the angle interference mirror 2 is disposed between the laser head 1 and the angle mirror 3, the angle mirror 3 is disposed on the turret upper disc 4, and the turret upper disc 4 is disposed at the gantry The turntable base 5 is provided with a groove, and the turntable lower plate 5 is disposed on the turntable base 6 through a groove.

In this example, the turret base 6 is provided with a connecting member 7, and the turret base 6 can be fixed to other external turrets through the connecting member 7, thereby improving the flexibility of use. The connecting piece 7 preferably comprises a bolt hole and/or a screw hole.

As shown in FIG. 5, the example further includes a rotating shaft 9, a driving member 10, an angle grating 11 and a control system 12, the rotating shaft 9 is fixedly disposed below the upper tray 4 of the turntable, and the driving member 10 and the rotating shaft 9 is connected, the driving member 10 is preferably a motor, the driving member 10 is fixedly disposed inside the lower tray 5 of the turntable; the angle grating 11 is disposed below the rotating shaft 9; the control system 12 The angle grating 11 and the motor are respectively connected, and the control system 12 is a member for realizing power supply and transmission of control commands.

In this example, the laser head 1 emits a laser beam split into two beams through the angle interference mirror 2, and is directed to the angle mirror 3. The angle mirror 3 reflects the laser light back to the angle interference mirror 2, and finally returns to the laser head 1; 4 and the middle of the turntable lower plate 5 is provided with a rotating shaft 9, which is preferably a concentric rotating shaft, the turntable upper plate 4 is fixed on the rotating shaft 9 and rotates together with the rotating shaft 9, and the angle reflecting mirror 3 is fixed on the turntable upper plate. 4, the inside of the turntable lower plate 5 is fixed with two motors, and the control system 12 controls the motor to move the rotating shaft 9 to rotate. The angle of rotation is measured by the angle grating 11 and is controlled for the motor. The rotation angle of the motor control shaft 9 is up to 1 Preferably, the turntable lower disk 5 has a built-in wireless signal receiving device, the angle mirror 3, the turntable upper disk 4, the turntable lower disk 5, the turntable base 6, the rotating shaft 9, the driving member 10, and the angle grating 11 The drive circuit of the turntable formed by the control system 12 can be powered by a battery.

As shown in FIG. 5, the center of the turntable base 6 is provided with a groove, and the turntable lower plate 5 is just stuck in the groove to keep the lower plate 5 fixed, and the entire turntable can also pass through a bolt hole or the like. The connector 7 is fixed to the other turret to be tested. After the turntable is fixed, after the angle mirror 3 is fixed on the turntable upper tray 4, an angle is input from the control system 12, so that the turntable upper tray 4 is rotated counterclockwise from the initial position, as shown in Fig. 6, laser interference The instrument measures and records the angle reading; then the angle in the turntable software is first reset to zero, the turntable 4 is returned to the initial zero position, and another angle is input from the control system 12 to make the turntable 4 from the initial position. Rotate the angle clockwise, as shown in Figure 7, the laser interferometer measures and records the angle of rotation to complete the calibration. Using the recorded data, the initial zero error and the constant of the angle mirror 3 can be calculated.

As shown in FIG. 4, the present embodiment further provides an angle measurement calibration system for a laser interferometer, comprising the angle measurement calibration device of the laser interferometer as described above, and comprising a data processing device 8, the data processing device 8 and The laser head 1 implements communication. The data processing device 8 is preferably a data processing device such as a computer.

As shown in FIG. 4, the angle measurement calibration system is set up, and the laser light emitted from the laser head 1 is adjusted to be vertically incident on the angle mirror 3 so that the zero angle of the actual initial position M ₀ is a ₀ and the optical path difference is d ₀ , the angle mirror constant design value is A, the actual angle mirror constant B=K·A, and K is the mirror constant coefficient. In the initial position, open the software corresponding to the laser angle interferometer in the computer or other data processing device 8, and clear the laser angle interferometer reading. When the initial zero angle is rotated counterclockwise, the laser angle interferometer reads '+'. Then turn on the turntable control software, first set the angle to zero, then input the rotation angle q _{1 in the} measurement range of the laser angle interferometer, rotate the upper plate of the turntable counterclockwise to the position M ₁ , the rotation angle is q ₁ , record the time The angle reading R _{1 of the} laser angle interferometer increases the optical path difference by Δδ ₁ ; the principle of the angle calibration of the counterclockwise rotation is shown in FIG. 6 .

After the above measurement is completed, the angle is set to zero, the upper plate 4 of the turntable is first adjusted back to the initial position M ₀ , and then an angle q _{2 is} input, and the upper plate 4 of the turntable is rotated clockwise by q ₂ to the position M ₂ . 4 Turn the angle to q ₂ , record the reading of the laser angle interferometer R ₂ at this time, take a positive value when calculating, reduce the optical path difference by Δδ ₂ ; the principle of angle calibration of clockwise rotation is shown in Figure 7.

According to the above measured values, combined with the optical path difference measurement transfer function, there is

Available

Where q ₁ and q ₂ are both positive values, Dd ₁ = AsinR ₁ , Dd ₂ = AsinR ₂ , and thus the initial zero angle α ₀ and the constant coefficient K of the angle mirror 3 are calculated.

In particular, when the absolute values of the standard angles of left and right rotation are equal, and both are q, the following expression is used:

The angle measuring and calibration device of the laser interferometer according to the present embodiment has a precise structure and a small standard angle error, and can calibrate the initial zero angle by actively generating a certain declination, and the declination can be actively generated by the angle grating 11 and the driving member 10. The generated angle is more accurate; on this basis, the initial zero error and the constant of the angle mirror 3 can be simultaneously calibrated during the calibration process, which simplifies the calibration procedure of the laser interferometer and improves the calibration efficiency.

The embodiments described above are preferred embodiments of the present invention, and are not intended to limit the scope of the present invention. The scope of the present invention is not limited to the specific embodiments, and the shapes and structures according to the present invention are Equivalent variations are within the scope of the invention.

Claims (10)

1. An angle measuring and calibrating device for a laser interferometer, comprising: a laser head, an angle interference mirror, an angle mirror, a turntable upper disc, a turntable lower disc and a turntable base, wherein the angle interference mirror is disposed on the laser Between the head and the angle mirror, the angle mirror is disposed on the upper tray of the turntable, the upper tray of the turntable is disposed on the lower tray of the turntable; the base of the turntable is provided with a groove, the turntable The lower plate is disposed on the base of the turntable through a groove.
2. The angle measuring and calibrating apparatus for a laser interferometer according to claim 1, wherein the turret base is provided with a connecting member, and the turret base is fixed to an external turret to be tested by a connecting member.
3. The angle measuring and calibrating apparatus for a laser interferometer according to claim 2, wherein the connecting member comprises a bolt hole and/or a screw hole.
4. The angle measuring and calibrating apparatus for a laser interferometer according to any one of claims 1 to 3, further comprising a rotating shaft and a driving member, the rotating shaft being fixedly disposed under the upper tray of the turntable, the driving member Connected to the rotating shaft.
5. The apparatus of claim 4, wherein the drive member is a motor.
6. The angle measuring and calibrating apparatus for a laser interferometer according to claim 4, wherein the driving member is fixedly disposed inside the lower tray of the turntable.
7. The apparatus of claim 4, further comprising an angle grating disposed below the shaft.
8. The angle measuring and calibrating apparatus for a laser interferometer according to claim 7, further comprising a control system, said control system being respectively coupled to said angle grating and said motor.
9. The angle measuring and calibrating apparatus for a laser interferometer according to any one of claims 1 to 3, further comprising a wireless signal receiving device, wherein the wireless signal receiving device is disposed inside the lower tray of the turntable.
10. An angle measurement calibration system for a laser interferometer, comprising the angle measurement calibration device of the laser interferometer according to any one of claims 1 to 9, and comprising a data processing device, the data processing device and the The laser head realizes communication.

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