CN203011370U - Calibrating apparatus for angle measuring device based on optical lever - Google Patents

Abstract

The angle measurement device verification device based on the optical lever belongs to the field of angle error measurement technology, which solves the problem of high cost of the existing angle measurement error verification device, including the lower turntable installed on the verification table, the bottom two-dimensional manual translation adjustment platform, The mounting seat of the angle measuring device to be tested, the two-dimensional manual translation adjustment platform in the middle, the upper turntable, the one-dimensional manual translation platform, the plane mirror, the laser, the photoelectric detector and the reading head. When in use, install the angle measuring device to be tested on the mounting base, and drive the upper turntable and the plane mirror to rotate by controlling the lower turntable , the reflected light deflects After incident on the target surface, and then control the reverse rotation of the upper turntable ; by the calibrated angle and a sequence of standard values for angle increments , to calculate the standard value sequence of the calibrated angle . The utility model has the advantages of simple structure, low manufacturing cost and improved precision of the angle measuring device.

Description

Calibration device for angle measuring device based on optical lever

technical field

The utility model belongs to the technical field of angle error measurement, in particular to a verification device for an angle measuring device.

Background technique

There are various methods of angle measurement, which can be roughly divided into mechanical methods (such as multi-tooth indexing disc, lever method), electromagnetic methods (such as circular magnetic grid, circular induction synchro) and photoelectric methods (such as optical dividing head, degree disc, regular polyhedral prism angle measurement, code disk angle measurement, grating angle measurement, ring laser angle measurement, laser interferometry angle measurement), etc.

The mechanical method is represented by a multi-tooth indexing plate, using high-precision gears as the basis for indexing, and can improve resolution and accuracy through differential motion. The advantage of this method is that the accuracy is relatively stable, and the measurement accuracy of the whole cycle is high; the disadvantage is that it is difficult to continue to improve the accuracy after reaching 0.1 arc seconds, which is mainly due to the extremely high concentric error requirements of each layer during multi-layer differential accumulation. . In addition, the equipment is heavy and the operation requirements are extremely high.

The electromagnetic method is represented by a circular induction synchronizer, which uses electromagnetic induction to convert the angular displacement into an electrical signal for angle measurement, and the accuracy can reach 0.5 arc seconds. The advantage of this method is that it has lower requirements on the environment and can be used in harsh conditions such as machine tools; the disadvantage is that there is drift, poor anti-interference and short life.

There are many types in the photoelectric method, and the accuracy is relatively high.

The circular grating uses the radial grating or tangential grating engraved on the circular plane of the glass disc and the moiré fringes produced by the index grating to measure the angle. This method can generally achieve a full circle accuracy of about 0.2 arc seconds, and the highest can reach 0.05 arc seconds, but high-precision circular optical grids are difficult to manufacture and expensive.

The ring grating is engraved on the cylindrical surface of a steel ring to measure the angle with the Moiré fringes produced by the index grating. It is a grating-type precision angle measuring device, which has the advantages of non-contact measurement, convenient installation, and digital reading. The accuracy of this device is close to that of a circular grating.

The ring laser angle measurement adopts the principle of laser gyroscope to measure the angular velocity, and then obtain the rotation angle. This method can achieve a measurement accuracy of 0.1 arc second, but this method is very difficult technically, only a few countries have mastered it, and the technology is not yet mature.

Laser interferometric angle measurement uses the method of interference to convert small angles into the movement of interference fringes to achieve angle measurement. The accuracy of this method is currently the highest. There are foreign research reports that can reach a sensitivity of 0.002 arc seconds, but this is only limited to the measurement of small angles. The instrument is quite complicated and expensive, and only a commercial laser interferometer costs millions of dollars, not to mention the high-precision measurement and related facilities required.

As far as angle encoders commonly used at present, such as dials, code discs, circular induction synchronizers, circular gratings, ring gratings, etc., the products produced have marking errors due to technological reasons, such as the 350mm produced by Renishaw in the United Kingdom. The ring gratings have a rule error of about 0.8 arc seconds, and the best ring grating products offered by the company have a rule error of about 0.5 arc seconds. This is intolerable for high-precision measurements, so the scoring errors of the goniometric devices must be corrected.

In the prior art, the optical lever principle is also used to measure the measurement of the micro linear displacement and the micro angular displacement.

The principle of light lever is based on the following facts: 1. According to the law of reflection, if the direction of the incident ray remains unchanged, when the reflecting surface rotates a certain angle θ, the direction of the reflected ray will rotate by 2θ; 2. The angle change of the reflected light, light There is an accurate conversion relationship between the arm length (that is, the distance from the incident point to the spot) and the moving distance of the spot.

The principle of the optical lever is shown in Figure 1. After a light beam is reflected by the plane mirror, the spot falls on the receiving screen. When there is a small displacement δL, the plane mirror rotates slightly, and the outgoing light is deflected at twice the angle. At the same time, due to the distance between the plane mirror and the scale The longer distance D causes the exit light spot to move a distance δn that is much greater than δL. by the formula

δL=δn/(2D/b)

The small displacement δL can be obtained.

2D/b is the magnification of the system.

The above is to use the light lever principle to calculate the micro-displacement. In fact, this principle can also be used to calculate the micro-angular displacement. When the reflective surface rotates by an angle α, the reflected light rotates by 2α, and α can be obtained by the following formula:

α=δL/b=δn/2D

Since the value of D is large, δn is also large, making it easy to measure.

The salient features of the optical lever principle are: with the lengthening of the optical arm, the resolution and precision of the measurement system increase almost linearly, with sensitive response and high precision. Most of the time, the optical lever principle is used as a small linear displacement measurement method, such as measuring the elastic modulus and creep of materials. Due to the conversion relationship between angle and linear displacement, this principle can also be used for the measurement of small angular displacement in addition to the measurement of small linear displacement. At present, there is no record of using the optical lever principle as the measurement calibration of goniometer devices.

Utility model content

There are different degrees of marking errors in any goniometric device products. However, due to reasons such as usage requirements, cost, and procurement restrictions, it is often difficult to buy angle measuring devices with suitable accuracy. For example, for high-precision measurement applications such as astrometry, the angle measurement accuracy needs to reach 0.01 arc seconds or higher, which puts forward very high requirements for the error of the angle measurement device itself, and even the current highest-precision angle measurement products are difficult. meet its requirements. Therefore, it is very necessary to verify and correct the angle measurement error.

On the other hand, the currently existing verification devices have the disadvantage of expensive components. For example, if a high-precision grating encoder is used for comparative verification, the grating is very expensive and difficult to obtain; Very expensive.

The purpose of the utility model is to provide an angle measuring device verification device with high verification accuracy, relatively low price and easy access to verification equipment.

The technical scheme adopted in the utility model is as follows:

Angle measuring device verification device based on optical lever:

Including the verification platform, the lower turntable is installed on the verification platform, the lower turntable is composed of the base and the lower turntable, and the rotating shaft on the lower turntable is set on the rolling bearing on the base;

The bottom two-dimensional manual translation adjustment platform is installed on the lower turntable through the adapter flange, and the mounting seat of the angle measuring device to be verified is installed on the bottom two-dimensional manual translation adjustment platform through the adapter flange;

The center of the top of the mounting base is equipped with a middle two-dimensional manual translation adjustment platform through an adapter flange;

The upper turntable is installed on the two-dimensional manual translation adjustment platform in the middle through the adapter flange;

The rotation centers of the lower turntable, the angle measuring device to be tested and the upper turntable are located on the same vertical line;

The upper turntable is composed of a base and an upper turntable, and the rotating shaft on the upper turntable fits on the rolling bearing on the base;

One-dimensional manual translation stage is installed on the upper turntable through the adapter flange;

A mirror frame is installed on the one-dimensional manual translation platform through an adapter flange, and a plane mirror is arranged on the mirror frame along the vertical direction, and the reflection surface of the plane mirror is located in the same plane as the rotation center of the upper turntable;

Lasers and photodetectors are installed on the verification platform, and the lasers and photodetectors are located on the same horizontal plane as the plane mirror, and the target surface of the photodetectors is parallel to the rotation center of the upper turntable;

The plane mirror, laser and photodetector constitute an optical lever;

A reading head for reading the angle value of the angle measuring device to be tested is installed on the verification platform;

Both the reading head and the photodetector are connected to the data processor through the data acquisition card;

Both the control systems of the upper turntable and the lower turntable are connected with the data processor.

As the preferred version of the utility model:

The angle measuring device to be tested is an angle encoder, an inductive synchronizer, a dial, a circular grating or a ring grating;

There are more than two reading heads for reading the rotation angle value of the angle measuring device to be verified, and the reading heads are arranged on the verification platform in a radial distribution along the outer circumference of the angle measuring device to be verified;

The data processor is a single-chip microcomputer or a computer;

The photodetector is a programmable control CCD camera.

When in use, place the angle measuring device to be tested horizontally and install it on the mounting base; adjust the two-dimensional manual translation adjustment platform at the bottom and the two-dimensional manual translation adjustment platform in the middle to make the rotation of the lower turntable, the angle measurement device to be tested, and the upper turntable The center is located on the same vertical line; by adjusting the one-dimensional manual translation stage, the reflective surface of the plane mirror and the rotation center of the upper turntable are in the same plane; the laser is controlled to emit laser light so that the incident light is incident on the reflective surface of the plane mirror, and the The rotation center of the upper turntable is orthogonal, so that the reflected light of the laser is vertically incident on the target surface of the photodetector.

The method for verifying the angle measuring device to be verified by using the above verification device includes the following sequential steps:

Step 1: Control the turntable to rotate at an equal angle step θ, perform multi-step sampling measurements on the angle measuring device to be verified, and collect the calibrated angle sequence β _i and the measurement value sequence α _i of the angle increment, including the following steps:

Step 1.1: collect the spot image data on the target surface of the photodetector as the starting point spot image data;

Step 1.2: Collect the reading value β of the calibrated angle and the measured value α of the angle increment, including the following steps:

The rotation axis of the lower turntable is controlled by the data processor to rotate according to the set rotation angle step θ, where θ=360°/n, n≥21600, the lower turntable drives the upper turntable and the plane mirror to rotate, and the reflected light of the plane mirror deflects at an angle of 2θ and then enters the On the target surface of the same photodetector, the end spot image is obtained;

Collect the image data of the spot at the end point, and calculate the angle increment value of the angle measuring device to be tested measured by the optical lever according to the following formula, as the measured value α of the angle increment:

α=arctan(δn/2D)

δn in the above formula is the straight-line distance from the starting spot image to the end spot image, and D is the optical arm or optical path, which represents the distance between the plane mirror and the target surface of the photodetector;

Collect the reading value of the angle of rotation of the angle measuring device to be tested through the reading head, as the calibrated angle β;

Step 1.3: The rotating shaft of the upper turntable is controlled by the data processor to reversely rotate according to the set rotation angle step θ, so that the reflected light of the plane mirror on the upper turntable reverses the angle 2θ and then vertically incident on the target surface of the photodetector, complete One-step sampling measurement, return to step 1.1 for next sampling measurement;

包括以下步骤：Step 2: Calculate the sequence of standard values for the angle increments

Include the following steps:

When the rotating shaft of the turntable rotates one revolution under the control of the data processor, after the nth step of sampling measurement is completed, the calibrated angle sequence β _i and the measured value sequence α _i of the angle increment are obtained, and the standard value sequence i of the angle increment is calculated according to the following formula

为所有角度增量的测量值的累加值；α _i in the above formula is the measured value of the ith angle increment, i is all positive integers from 1 to n,

is the accumulated value of the measured values of all angle increments;

Step 3: Calculate the standard value sequence φ _i of the calibrated angle corresponding to the calibrated angle sequence β _i according to the following formula:

为第1至i步采样测量中计算得到的角度增量的标准值序列的累加值。i in the above formula is all positive integers from 1 to n,

It is the standard value sequence of the angle increment calculated in the sampling measurement from step 1 to i accumulated value.

In the above verification method, the angle step length θ≥1 arcmin can be taken, and the light arm D≥5m.

The verification method carried out by using the device of the utility model is to install the absolute angle encoder to be tested on a specially designed turntable. The turntable is a double-axis design. The axes of the upper and lower rotating shafts coincide, but their rotations can be controlled separately. A beam of laser light is reflected by the plane mirror, and a CCD camera is placed at a distance of about 10m (optical path). When the plane mirror rotates a small angle with the upper turntable, the position of the spot will change, and the CCD camera can detect it. make this change. Because the optical arm is 10m, even at a small angle (such as 0.1 arcsecond), the position of the spot will have a large movement (5 microns), and this displacement can be accurately obtained by image processing. Due to the size limitation of the CCD target surface, the plane mirror can only rotate a small angle with the outer ring, such as 1 arc minute or 0.1 arc second. Return to the vicinity of the starting point again, and then the next small-angle detection can be carried out until the whole week detection is completed.

During the whole detection process, the multi-head reading system supporting the angle encoder will read the angle change. After the whole cycle detection is completed, the angular displacement of each step can be obtained after processing the CCD detection image, and the closed adjustment is performed after summing. Since the angle of the entire circumference is 360°, this is a known quantity, so when the entire circumference measurement is completed, the measured value of each step should be accumulated to be equal to 360°, but due to measurement errors, the accumulated value is not equal to 360° , this difference <360°-cumulative value> is poor closure. Divide this difference by the number of measurements n to get the correction number v, and add the correction number to each measurement value to get the adjustment value of the measurement. This method is the closed adjustment method commonly used in surveying. Using this method, the angular displacement detection value of each step can be obtained, that is, the adjusted value obtained by closed adjustment of the measured quantity of each step. Based on this detection value, the reading of the angle encoder can be compensated and corrected: for each step of measurement, there are two sets of corresponding detection values: the reading of the angle encoder and the measurement value of the optical lever. The compensation method used here is to measure the optical lever Value as a standard, subtract the reading value of the angle encoder from the measured value of the light lever, and then correspond this value with the measured value of the angle encoder one by one to form a digital table. After using the angle encoder reading head to make an angle measurement reading, the above-mentioned digital table can be used to perform the difference to obtain the measured correction number, and the angle encoder reading is added to the correction number to obtain the corrected measurement result. This is compensation correction. Using the method proposed in this case, the correction values corresponding to a series of small rotation angle indications are obtained. Next, the indicated values of these small rotation angles are accumulated sequentially (sequential accumulation means: for example, there are 5 steps, and the step length of each step is 5', then the following numerical columns can be obtained: "0, 5, 10, 15 , 20, 25". More steps are analogized, and the step length of each step does not have to be absolutely equal.), to obtain a series of incremental angle indications, and also accumulate the corrected values in turn to obtain a series of incremental The corrected value of . These two columns of values can form a correction table (the content of the correction table is two columns of data: the first column is the fixed angle value, generally corresponding to the display of the angle measuring device, and the second column is when the display of the angle measuring device is corresponding to the first The value of a line is the value after the corresponding corrected value, that is, the true value), and the corrected measurement result can be obtained by interpolation calculation based on the measurement indication obtained in the actual measurement as an argument.

The entire detection process of the above-mentioned verification method is controlled by a computer program to realize automatic static detection; the code disc reading and CCD acquisition are managed by the same control and acquisition software system to realize automatic detection, and the data obtained after the whole week of detection is processed and analyzed; the entire system should be set In a closed, light-proof laboratory.

The above verification method corresponds the two kinds of data according to the time series, and the result of the optical lever detection system can be used to correct the marking error of the angle encoder. There are two sets of data in the experiment, one set is the data obtained by the reading head of the angle encoder, and the other set is the camera data of the optical lever detection system. These two sets of data should be corresponding to each other and collected simultaneously before they can be used for analysis and processing of the results. Therefore, the control and data collection of the whole system need to have a unified coordinated control. Validation experiments are planned for static detection, simply collecting with the turntable stationary before each step is started and after each rotation. During the formal inspection, the optical lever inspection experimental system has been fully and necessary designed and debugged.

The device of the utility model can realize the verification of the angle measuring device with higher precision, and the verification accuracy can be improved with the increase of the length of the optical arm of the optical lever. Thereby greatly improving the accuracy of measurement. The structure of the device of the utility model is simple and easy to obtain. The verification method carried out by the device of the utility model is simple and easy to implement, and the cost is low. It can provide correction numbers for high-precision angle measurement and improve the precision of the angle measurement device.

Description of drawings

Fig. 1 is a schematic diagram of the principle of an optical lever in the prior art;

Fig. 2 is the cross-sectional view of the verification device of the angle measuring device based on the optical lever of the present invention;

Fig. 3 is the optical path schematic diagram of the optical lever in the utility model;

Fig. 4 is a sectional view of the lower turntable in Fig. 2;

Fig. 5 is a sectional view of the upper turntable in Fig. 2;

FIG. 6 is a schematic perspective view of the testing device in FIG. 2 .

Detailed ways

The goniometric device verification device based on the optical lever includes a verification table 1 arranged in a closed, light-proof room, as shown in Figure 2, and a lower turntable 2 is installed on the verification table 1, as shown in Figure 4, the lower turntable 2 consists of The base 22 and the lower turntable 23 are formed, and the rotating shaft 24 on the lower turntable 23 is set on the rolling bearing 25 on the base 22;

Install the bottom two-dimensional manual translation adjustment platform 4 with the adapter flange 3 on the lower turntable 23, and install the mounting seat 6 of the angle measuring device 7 to be verified with the adapter flange 5 on the bottom two-dimensional manual translation adjustment platform 4;

The angle measuring device 7 to be tested is an annular angle encoder;

Place the angle measuring device 7 to be tested horizontally on the top periphery of the mounting base 6;

Install the central two-dimensional manual translation adjustment platform 16 with an adapter flange 8 at the top center of the mounting base 6;

Install the upper turntable 10 with the adapter flange 9 on the two-dimensional manual translation adjustment platform 16 in the middle;

By adjusting the bottom two-dimensional manual translation adjustment platform 4 and the middle two-dimensional manual translation adjustment platform 16, the rotation centers of the lower turntable 2, the angle measuring device 7 to be verified and the upper turntable 10 are located on the same vertical line;

As shown in Figure 5, the upper turntable 10 is composed of a base 26 and an upper turntable 27, and the rotating shaft 28 on the upper turntable 27 is set on the rolling bearing 29 on the base 26;

On the upper turntable 10, a one-dimensional manual translation stage 12 is installed with an adapter flange 11;

On the one-dimensional manual translation platform 12, the mirror frame 14 is installed with an adapter flange 13, and the mirror frame 14 is provided with a plane mirror 15 along the vertical direction. By adjusting the one-dimensional manual translation platform 12, the reflection surface of the plane mirror 15 is aligned with the upper turntable The rotation centers of 10 are located in the same plane;

Install the laser 17 and the photodetector 18 on the verification table 1, make the laser 17 and the photodetector 18 and the plane mirror 15 be located on the same horizontal plane, make the target surface of the photodetector 18 parallel to the rotation center of the upper turntable 10;

Described plane mirror 15, laser device 17 and photodetector 18 constitute optical lever;

A reading head for reading the rotational angle value of the angle measuring device 7 to be verified is installed on the verification platform 1;

Both the reading head and the photodetector 18 are connected with the data processor through the data acquisition card;

The control systems of the upper turntable 10 and the lower turntable 2 are all connected with the data processor;

As shown in Figure 3, the laser 17 is controlled to emit laser light, so that the incident light ray 19 is incident on the reflective surface M of the plane mirror 15, which is perpendicular to the rotation center of the upper turntable 10, so that the reflected light ray 20 of the laser light is perpendicularly incident on the surface of the photodetector 18. On the target surface, M in FIG. 3 represents the state when the plane mirror 15 is at the initial position, and N is the normal of the reflecting surface M when the plane mirror 15 is at the initial position.

The method for verifying the angle measuring device 7 to be verified by using the above-mentioned device comprises the following sequential steps:

Step 1: Control the lower turntable 2 to rotate at an equal angle step θ, perform multi-step sampling measurement on the angle measuring device 7 to be verified, and collect the calibrated angle sequence β _i and the measured value sequence α _i of the angle increment, including the following steps:

Step 1.1: collect the spot image data on the target surface of the photodetector 18 as the starting point spot image data;

Step 1.2: Collect the measured value α of the calibrated angle β and angle increment, including the following steps:

The rotating shaft 24 of the lower turntable 2 is controlled by the data processor to rotate according to the set rotation angle step θ, where θ=360°/n, n≥21600, the lower turntable 2 drives the upper turntable 10 and the plane mirror 15 to rotate, as shown in Figure 3 , after the reflected light 20 of the plane mirror 15 is deflected by an angle of 2θ, the obtained reflected light 21 is incident on the target surface of the photodetector 18 to obtain an end point spot image. M' in FIG. 3 represents the state when the plane mirror 15 is at the end position, N ' is the normal line of the reflective surface M' when the plane mirror 15 is at the terminal position;

Collect the image data of the spot at the end point, and calculate the angle increment value of the angle measuring device to be tested measured by the optical lever according to the following formula, as the measured value α of the angle increment:

α=arctan(δn/2D)

δn in the above formula is the straight-line distance from the starting point spot image to the end point spot image, and D is an optical arm or an optical path, representing the distance between the plane mirror 15 and the target surface of the photodetector 18;

Collect the reading value of the angle of rotation of the angle measuring device 7 to be tested by the reading head as the calibrated angle β;

Step 1.3: The rotating shaft 28 of the upper turntable 10 is controlled by the data processor to reversely rotate according to the set rotation angle step θ, so that after the reflected light 21 of the plane mirror 15 on the upper turntable 10 reverses the angle 2θ, the obtained reflected light 20 is vertical Incident to the target surface of photodetector 18, complete one-step sampling measurement, return to step 1.1 to carry out next step sampling measurement;

包括以下步骤：Step 2: Calculate the sequence of standard values for the angle increments

Include the following steps:

When the rotating shaft 24 of the turntable 2 under the control of the data processor rotates one circle, after the nth step of sampling measurement is completed, the calibrated angle sequence β _i and the measured value sequence α _i of the angle increment are obtained, and the standard value of the angle increment is calculated according to the following formula sequence

为所有角度增量的测量值的累加值；α _i in the above formula is the measured value of the ith angle increment, i is all positive integers from 1 to n,

is the accumulated value of the measured values of all angle increments;

Step 3: Calculate the standard value sequence φ _i of the calibrated angle corresponding to the calibrated angle sequence β _i according to the following formula:

为第1至i步采样测量中计算得到的角度增量的标准值序列

的累加值。i in the above formula is all positive integers from 1 to n,

It is the standard value sequence of the angle increment calculated in the sampling measurement from step 1 to i

accumulated value.

There are four reading heads for reading the rotation angle value of the angle measuring device 7 to be verified, and the four reading heads are arranged on the verification table 1 along the outer circumference of the angle measuring device 7 to be verified in a radial distribution;

The data processor is a computer;

Described photodetector 18 is the programmable control CCD camera that long side is 30mm;

The rotation angle step θ may be 1 arc minute, and the optical arm D may be 10 m.

Claims (2)

1. The angle-measuring device verification device based on optical lever, it is characterized in that: Including the verification platform, the lower turntable is installed on the verification platform, the lower turntable is composed of the base and the lower turntable, and the rotating shaft on the lower turntable is set on the rolling bearing on the base; The bottom two-dimensional manual translation adjustment platform is installed on the lower turntable through the adapter flange, and the mounting seat of the angle measuring device to be verified is installed on the bottom two-dimensional manual translation adjustment platform through the adapter flange; The center of the top of the mounting base is equipped with a middle two-dimensional manual translation adjustment platform through an adapter flange; The upper turntable is installed on the two-dimensional manual translation adjustment platform in the middle through the adapter flange; The rotation centers of the lower turntable, the angle measuring device to be tested and the upper turntable are located on the same vertical line; The upper turntable is composed of a base and an upper turntable, and the rotating shaft on the upper turntable fits on the rolling bearing on the base; One-dimensional manual translation stage is installed on the upper turntable through the adapter flange; A mirror frame is installed on the one-dimensional manual translation platform through an adapter flange, and a plane mirror is arranged on the mirror frame along the vertical direction, and the reflection surface of the plane mirror is located in the same plane as the rotation center of the upper turntable; Lasers and photodetectors are installed on the verification platform, and the lasers and photodetectors are located on the same horizontal plane as the plane mirror, and the target surface of the photodetectors is parallel to the rotation center of the upper turntable; The plane mirror, laser and photodetector constitute an optical lever; A reading head for reading the angle value of the angle measuring device to be tested is installed on the verification table; Both the reading head and the photodetector are connected to the data processor through the data acquisition card; Both the control systems of the upper turntable and the lower turntable are connected with the data processor. 2. The goniometric device verification device based on optical lever according to claim 1, characterized in that: The angle measuring device to be tested is an angle encoder, an inductive synchronizer, a dial, a circular grating or a ring grating; There are more than two reading heads for reading the rotation angle value of the angle measuring device to be verified, and the reading heads are arranged on the verification platform in a radial distribution along the outer circumference of the angle measuring device to be verified; The data processor is a single-chip microcomputer or a computer; The photodetector is a programmable control CCD camera.

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