Roll angle measurement device and method based on array-type multiple reflections

A technology of roll angle measurement and multiple reflections, applied in the direction of measuring devices, optical devices, instruments, etc., can solve problems such as difficult resolution, and achieve the effect of improving resolution

Active Publication Date: 2012-09-05

XI AN JIAOTONG UNIV

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Abstract

The invention discloses a roll angle measurement device and a roll angle measurement method based on array-type multiple reflections, wherein the device comprises a dual-frequency laser, a 1/2 wave plate and two sets of cube-corner prism arrays; a beam-splitting prism is arranged at the back of an optical axis of the dual-frequency laser, and a first analyzer and a first photoelectric receiver are arranged on a reflecting optical axis of the beam-splitting prism; a 1/4 wave plate is arranged on a transmitting optical axis of the beam-splitting prism; the 1/2 wave plate is located between the two sets of cube-corner prism arrays; a right-angled reflecting prism is arranged on an emitting optical axis of the two sets of cube-corner prism arrays, and a second analyzer and a second photoelectric receiver are arranged on a reflecting optical axis of the right-angled reflecting prism; and the output end of the first photoelectric receiver and the output end of the second photoelectric receiver are connected with a phase meter. According to the device and the method, detection components are arranged in the two sets of cube-corner prism arrays, thus effectively applying an array-type multiple reflection method used for displacement measurement to roll angle measurement. The problem of the difficulty of measuring a roll angle which is vertical to the direction of a laser beam in the conventional laser interferometry is overcome, and the advantage of relatively high roll angle measurement resolution compared with the prior art is obtained.

Application Domain

Using optical means

Technology Topic

PhysicsRolling angle +8

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[0019] The present invention will be described in further detail below in conjunction with the accompanying drawings:

[0020] See figure 1 with figure 2 , The present invention is based on an array-type multiple reflection roll angle measuring device, which includes a dual-frequency laser 1, a 1/2 wave plate 7 and two sets of corner cube arrays; a beam splitting prism 2 is provided behind the optical axis of the dual-frequency laser 1, The reflection optical axis of the beam splitter 2 is provided with a first analyzer 3 and a first photoelectric receiver 4; the transmission optical axis of the beam splitter 2 is provided with a quarter wave plate 5; the 1/2 wave plate 7 is located in two sets The middle of the corner cube array; a right angle reflecting prism 8 is provided on the exit optical axis of the two sets of corner cube arrays, and a second analyzer 9 and a second photoreceiver 10 are provided on the reflecting optical axis of the right angle reflecting mirror 8 The output ends of the first photoelectric receiver 4 and the second photoelectric receiver 10 are connected with a phase meter 11, which is connected to the computer 12. As shown in the figure, the two sets of corner cube arrays of the present invention are composed of a first corner cube array 6a and a second corner cube array 6b arranged in parallel. The 1/2 wave plate 7 is located in the first and second corner cube arrays 6a. , Between 6b.

[0021] Based on the above devices, the roll angle measurement method proposed by the present invention is specifically as follows:

[0022] 1) The beam emitted by the dual-frequency laser 1 is split into two beams through the beam splitting prism 2, where the reflected beam is received by the first photoelectric receiver 4 after the first analyzer 3, and regarded as a reference signal;

[0023] 2) The transmitted light beam emitted by the beam splitting prism 2 passes through the quarter wave plate 5, and then enters two sets of corner cube arrays. The two sets of corner cube arrays repeatedly reflect the light beam to pass through the 1/2 wave plate 7n times. , It is emitted to the right-angle mirror 8, and then received by the second photoelectric receiver 10 after the second analyzer 9 as a measurement signal;

[0024] 3) The measured signal and the reference signal are phase-detected by the phase meter 11. According to the relationship between the phase change and the roll angle, the roll angle of the 1/2 wave plate is calculated as the measured roll angle.

[0025] In the method and device of the present invention, the 1/2 wave plate between the two sets of corner cube arrays is used as the detection element, the laser phase change is used as the detection target, and the beam is used to pass through the 1/2 wave plate multiple times to make the measured angle Achieve greater gain, so that the phase change of the orthogonally polarized laser is correspondingly increased, thereby significantly improving the measurement resolution (sensitivity) of the roll angle. It is suitable for measuring the error of the rolling angle of the motion pair of precision guide rails and the motion axis of CNC machine tools.

[0026] The invention effectively places the detection element of the polarized laser phase method in the array corner cube, and makes full use of the beam to transmit through the detection element multiple times to increase the phase change to achieve the purpose of angular amplification. The method of the invention can solve the problems of roll angle measurement and its resolution is difficult to improve. Compared with existing methods and technologies, it obviously has the advantage of higher resolution.

[0027] See figure 1 The working process of the present invention is as follows: the dual-frequency laser 1 emits a dual-frequency laser beam, which is divided into two beams (reflected beam and transmitted beam) by a beam splitting prism 2 with a reflectivity of 50%; the reflected beam passes through the analyzer 3 and is The photodetector 4 receives it as a reference signal. The transmitted light beam passes through the 1/4 wave plate 5, and then passes through the detection element (1/2 wave plate) 7, and is reflected back by the corner cube array 6b, and then passes through the 1/2 wave plate 7. The /2 wave plate 7 reaches once; then the light beam reaches the corner cube array 6a and is reflected. Under the action of the two corner cube arrays 6a and 6b, the light beam passes through the 1/2 wave plate 7 for the second time; This beam passes through the 1/2 wave plate 7 for n times between the two corner cube arrays 6a and 6b, and then exits to the right-angle reflecting prism 8, passes through the analyzer 9, and is received by the photodetector 10, which is Measure the signal. The phase meter 11 measures the phase of the measurement signal and the reference signal, and calculates the value of the measured roll angle (the roll angle of the 1/2 wave plate 7) based on the relationship between the phase change and the roll angle, thereby realizing the roll angle measurement. The mathematical expression (mathematical model) of its phase change and roll angle is as follows:

[0028] Such as figure 1 As shown, let the orthogonal polarization photoelectric vectors be E 1 And E 2 , And E 1 The angle between the fast axis (F axis) of the 1/4 wave plate 5 and the x axis is θ; the angle between the F axis and the x axis of the 1/2 wave plate 7 is α; The number of times is n. The Jones matrix can be used to represent the measurement signal as follows:

[0029] E → S = PH 1 ( - α ) H 1 ( α ) H 2 ( - α ) H 2 ( α ) . . . H n ( - α ) H n ( α ) QR ( θ ) E → 0 - - - ( 1 )

[0030] Among them, P is the Jones matrix of the polarizer; H n It means the Jones matrix when passing through 1/2 wave plate 7 for the nth time (this symbol is for easy understanding and calculation), which is substantially equal to Jones matrix H of 1/2 wave plate 7; Q is 1/4 wave plate 5 Jones matrix of; R(θ) is the rotation matrix; Is the Jones vector representation of the beam. They are:

[0031] P = 1 0 0 0 , H ( α ) = cos 2 α sin 2 α sin 2 α - cos 2 α ,

[0032] Q = 1 0 0 i ,

[0033] H ( α ) = cos θ - sin θ sin θ cos θ ,

[0034] It is proved by mathematical induction that the formula for measuring the roll angle Δα is:

[0035] Δα = Δψ K a = - Δψ 4 n ( tan θ + cot θ ) - - - ( 2 )

[0036] Among them, Δα is the small change of α in a certain range, which is caused by the rolling of 1/2 wave plate 7, and is the measured roll angle; Δψ is the corresponding phase change caused by the roll angle, K a Is the angular gain coefficient. In formula (2), θ is known, and θ can be 2°; n is 12 or greater; therefore, the angular gain coefficient K can be determined a , Then K a =-1376. With a phase meter resolution of 0.01°, the angular resolution of this method can reach 0.026" or less.

[0037] Therefore, compared with the existing roll angle detection method, the angular resolution (sensitivity) of the method and device of the present invention is more than 10 times that of the existing method. It has a higher roll angle measurement resolution and can be used for precision rail movement. The roll angle measurement of auxiliary and high-end CNC machine tools provides more precise and higher resolution detection methods and technologies.

[0038] The method of the present invention is suitable for the field of high-precision industrial measurement, especially suitable for precision guide rail motion pairs and equipment based on it, such as: the roll angle error measurement of high-end CNC machine tools. Its wide application can greatly promote precision machinery and high-end The development of equipment manufacturing and testing technologies.

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High resolution

Roll angle measurement device and method based on array-type multiple reflections

A technology of roll angle measurement and multiple reflections, applied in the direction of measuring devices, optical devices, instruments, etc., can solve problems such as difficult resolution, and achieve the effect of improving resolution

AI-Extracted Technical Summary

Problems solved by technology

Abstract

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Description & Claims & Application Information

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