Absolute horizontal alignment measuring device and measuring method

Abstract

The present invention discloses an absolute horizontal directrix measuring device and a measuring method, wherein the measuring device comprises a coherent light source, an incoherent light source, a beam splitter, a collimator, a horizontal liquid level standard, a right angle prism and a CCD photoelectric detector, wherein the coherent light source and the incoherent light source are connected to the input end of the collimator through a two-in-one optical fiber coupler, a two-dimensional adjustable base is arranged below the collimator, the optical path output end of the collimator is connected to the optical path input end of the beam splitter, the first optical path output end of the beam splitter is connected to the input end of the right angle prism, the second optical path output end of the beam splitter is connected to the horizontal liquid level standard, and the output end of the right angle prism is connected to the detection input end of the CCD photoelectric detector after passing through an achromatic lens and a plano-convex lens in sequence. The present invention uses an infrared incoherent laser as a collimated detection laser to share an optical path with the absolute horizontal directrix, and adjusts the position of the absolute horizontal directrix to obtain an absolute horizontal directrix that can be traced back to the wavelength of light.

Description

Technical Field

[0001] The present invention can be applied in the technical field of horizontal alignment measurement, and specifically is an absolute horizontal alignment measurement device and a measurement method. Background Art

[0002] According to the different traceability benchmarks of the horizontal line, the current methods of establishing the horizontal line are mainly divided into two categories: one is to establish the horizontal line based on the plumb plane of the hanging mirror, and the other is to establish the horizontal line based on the horizontal plane.

[0003] Due to the limitation of the mechanical structure of the hanging mirror and the processing error of the parallel plane reflector, the mirror surface cannot be completely kept plumb; due to the processing error of the pentagonal prism, the incident light and the outgoing light cannot be completely kept perpendicular, resulting in the horizontal alignment accuracy established by these two methods being restricted by the accuracy of the hanging mirror and the pentagonal prism, respectively, and difficult to further improve. Therefore, an absolute horizontal alignment measurement device and measurement method are needed. Summary of the invention

[0004] In view of the above deficiencies in the prior art, the purpose of the present invention is to provide an absolute horizontal line measuring device and a measuring method, which aims to establish an absolute horizontal line based on the principle of plane interference and with the natural liquid surface as the horizontal reference, so as to realize long-distance absolute horizontal line and tilt angle measurement.

[0005] The measuring device of the present invention comprises a coherent light source, an incoherent light source, a beam splitter, a collimator, a horizontal liquid level standard, a right-angle prism and a CCD photoelectric detector. The coherent light source and the incoherent light source are connected to the input end of the collimator through a two-in-one optical fiber coupler, a two-dimensional adjustable base is arranged below the collimator, the optical path output end of the collimator is connected to the optical path input end of the beam splitter, the first optical path output end of the beam splitter is connected to the input end of the right-angle prism, the second optical path output end of the beam splitter is connected to the horizontal liquid level standard, the output end of the right-angle prism is connected to the detection input end of the CCD photoelectric detector through an achromatic lens and a plano-convex lens in sequence, and the CCD photoelectric detector is connected to a computer.

[0006] Furthermore, the coherent laser is a helium-neon coherent laser with a wavelength of 633 nm.

[0007] Furthermore, the incoherent laser is an infrared incoherent laser with a wavelength of 1550 nm.

[0008] Furthermore, the focal length of the objective lens of the collimator is 500 mm, and the aperture of the objective lens is 50 mm.

[0009] An absolute horizontal alignment measurement method uses a horizontal liquid surface as an absolute horizontal reference, and uses a plane interferometry method to establish interference fringes between the horizontal liquid surface and a target mirror using coherent lasers to achieve measurement of a horizontal alignment or a tilt angle;

[0010] On the basis of absolute horizontal alignment measurement, a position sensitive detector is used to measure the relative position and angular relationship between the coaxial coherent laser and the incoherent laser beam. The long-distance horizontal alignment measurement is achieved by the change of the position of the incoherent laser on the position sensitive detector at a long distance.

[0011] Furthermore, the target mirror includes a hanging mirror or a flat crystal.

[0012] Furthermore, the planar interference method includes Fizeau interferometry, Tyemann interferometry or digital interferometry.

[0013] Furthermore, a hanging mirror is arranged in the transmission direction of the measuring light beam of the measuring device, and the horizontal liquid level standard and the hanging mirror are used as independent absolute horizontal references. The specific steps are as follows:

[0014] S1. Set the hanging mirror on the same measuring beam transmission path of the measuring device, turn on the coherent light source to demodulate the interference pattern formed by the coherent laser reflected by the horizontal liquid surface and the self-leveling suspended parallel plane reflector, and obtain the angle between the two at this time. ;

[0015] S2. Rotate the parallel plane mirror 180° and demodulate the interference pattern formed by the coherent laser reflected by the horizontal liquid surface and the self-leveling suspended parallel plane mirror to obtain the angle between the two at this time. ;

[0016] S3. Obtain the absolute zero position of the measuring beam relative to the horizontal liquid surface , adjust the two-dimensional adjustable base so that the measuring beam is absolutely horizontal.

[0017] Furthermore, the long-distance horizontal angle measurement comprises the following specific steps:

[0018] S1, a dichroic mirror, a pinhole diaphragm, and a PSD position sensitive detector are sequentially arranged along the transmission direction of the measuring beam of the measuring device, and the spacing of the PSD position sensitive detector is adjusted by a translation stage;

[0019] S2, turn on the incoherent light source, the measuring light beam passes through the dichroic mirror, the coherent laser returns, and interferes with the coherent laser reflected by the horizontal liquid surface, which is used to measure the horizontal deviation angle of the measuring light beam; the incoherent laser is transmitted and hits the PSD position sensitive detector through the small diameter aperture;

[0020] S3. According to the change of the spot position on the PSD position sensitive detector and the moving distance of the translation stage, the horizontal deflection angle of the translation stage is calculated to achieve long-distance horizontal angle measurement.

[0021] Furthermore, the calculation formula of the horizontal deflection angle of the translation stage is as follows:

[0022] If the light spot received by the PSD position sensitive detector changes from position 0 to position 1 in the horizontal direction:

[0023]

[0024] Among them, on the PSD position sensitive detector, the coordinates of position 0 are , the coordinates of position 1 are , is the distance that the PSD position sensitive detector moves when driven by the translation stage. is the horizontal deflection angle of the translation stage.

[0025] Compared with the prior art, the present invention has the following beneficial effects:

[0026] The present invention uses infrared incoherent laser as a collimated detection laser and shares the same optical path with an absolute horizontal alignment, constructs a long-distance absolute horizontal laser alignment based on collimated detection, and compensates for the horizontal angle deviation of the measuring light beam and adjusts the position of the absolute horizontal alignment to obtain an absolute horizontal alignment traceable to the wavelength of light. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 This is a schematic diagram of the structure of a long-distance absolute horizontal alignment measuring device of the present invention;

[0028] Figure 2 A schematic diagram of the structure for establishing an absolute horizontal alignment for the present invention;

[0029] Figure 3 This is a schematic diagram of the structure of the long-distance horizontal angle measurement of the present invention;

[0030] Figure 4 It is a diagram showing the horizontal position change of the light spot on the PSD position sensitive detector of the present invention;

[0031] Figure 5 The schematic diagram of the calculation principle of the horizontal deflection angle of the translation platform of the present invention;

[0032] Among them, 1-coherent light source, 2-incoherent light source, 3-two-in-one fiber coupler, 4-parallel light tube, 5-beam splitter, 6-horizontal liquid level standard, 7-right angle prism, 8-achromatic lens, 9-plano-convex lens, 10-CCD photodetector, 11-computer, 12-two-dimensional adjustable base, 13-hanging mirror, 14-dichroic mirror, 15-pinhole aperture, 16-PSD position sensitive detector, 17-translation stage. DETAILED DESCRIPTION

[0033] The specific implementation of the present invention is further described in detail below in conjunction with the accompanying drawings and examples. The following examples are used to illustrate the present invention, but are not intended to limit the scope of the present invention.

[0034] like Figure 1 As shown, a long-distance absolute horizontal alignment measuring device is essentially a laser liquid level interferometer with a fine-tuning mechanical structure, including a coherent light source 1, an incoherent light source 2, a two-in-one optical fiber coupler 3, a collimator 4, a beam splitter 5, a horizontal liquid level standard 6, a right-angle prism 7, an achromatic lens 8, a plano-convex lens 9, a CCD photodetector 10, a computer 11, and a two-dimensional adjustable base 12; the collimator 4 is fixed on the two-dimensional adjustable base 12, and the light emitted by the coherent light source 1 and the incoherent light source 2 is transmitted through the two-in-one optical fiber coupler. 3 is coupled and transmitted to the collimator 4, which is collimated into a parallel light beam output by the collimator 4, and then the parallel light beam is divided into a reference beam and a measuring beam by the beam splitter 5. After the reference beam is reflected by the horizontal liquid level standard 6, it converges and interferes with the measuring beam reflected back at the beam splitter 5 to form an interference beam. The interference beam is deflected by the right-angle prism 7, and then it is condensed by the achromatic lens 8 and the plano-convex lens 9 and converged on the CCD photoelectric detector 10. The CCD photoelectric detector 10 collects the interference signal and transmits it to the computer 11 for processing.

[0035] The coherent laser 1 is a helium-neon coherent laser with a wavelength of 633 nm, the incoherent laser 2 is an infrared incoherent laser with a wavelength of 1550 nm, the focal length of the objective lens of the collimator 4 is 500 mm, and the aperture of the objective lens is 50 mm.

[0036] The long-distance absolute horizontal alignment measurement method specifically includes establishing an absolute horizontal alignment and long-distance absolute horizontal alignment measurement.

[0037] Theoretically, the highest accuracy of horizontal alignment tracing can be traced back to the wavelength of light. Therefore, by combining the principle of optical interference and using a laser liquid level interference device plus a corresponding fine-tuning mechanical structure, the horizontal alignment can be traced with higher accuracy. The parallel light tube used in the present invention is specially designed for infinite applications. It can ensure that the outgoing laser is absolutely parallel, but it cannot ensure the horizontality of the laser. In addition, the beam splitter will also produce an angular deflection effect on the outgoing laser. Under the combined influence, the measuring light beam deviates from the horizontal. Therefore, as long as the horizontal angle deviation of the measuring light beam is obtained and compensated, the absolute horizontal alignment can be accurately obtained. Figure 2 As shown, on the basis of the above-mentioned long-distance absolute horizontal alignment measuring device, a hanging mirror 13 is set in the transmission direction of the measuring light beam. With the horizontal liquid level standard 6 and the hanging mirror 13 as independent absolute horizontal references, combined with the principle of laser liquid level interference, the self-leveling suspended parallel plane reflector is rotated 180° around the vertical axis, and the angular bisector of the angle between the normal lines of the two reflecting surfaces is the horizontal line. The absolute zero position of the measuring light beam relative to the horizontal liquid surface, that is, the horizontal angle deviation of the measuring light beam is obtained, and the posture of the collimator 4 is adjusted by adjusting the pitch of the two-dimensional adjustable base 12 to compensate for the angle deviation, and an absolute horizontal alignment that can be traced back to the wavelength of light is established. The specific steps are as follows:

[0038] S1, placing the device and the hanging mirror 13 on the large-scale baseline, and turning on the helium-neon light source 1;

[0039] S2. Demodulate the interference pattern formed by the He-Ne laser reflected by the horizontal liquid surface and the self-leveling suspended parallel plane mirror to obtain the angle between the two at this time. ;

[0040] S3, self-leveling suspended parallel plane mirror rotated 180°

[0041] S4. Demodulate the interference pattern formed by the He-Ne laser reflected by the horizontal liquid surface and the self-leveling suspended parallel plane reflector to obtain the angle between the two at this time. ;

[0042] S5. Obtain the absolute zero position of the measuring beam relative to the horizontal liquid surface , adjust the two-dimensional adjustable base 12 to compensate for the horizontal angle deviation so that the measuring beam is absolutely horizontal.

[0043] The specific compensation method is as follows: After the interference pattern is unwrapped, a Zernike fitting is performed. The third term in the fitted Zernike polynomial reflects the angular deviation of the reflector surface relative to the horizontal liquid surface in the vertical direction. ,in That is, and , is the coefficient of the third term. >0 indicates that the reflector is tilted upward in the vertical direction. <0 indicates that the reflector surface is tilted downward in the vertical direction. Based on the characteristics of the self-leveling suspended parallel plane reflector, if =0, it indicates that the measuring beam is absolutely horizontal. <0, it indicates that the measuring beam deviates upward relative to the horizontal direction, so adjust the pitch knob of the two-dimensional adjustable base to make the measuring beam deviate downward; if >0, it indicates that the measuring beam deviates downward relative to the horizontal direction. Then adjust the pitch knob of the two-dimensional adjustable base to make the measuring beam deviate upward. Repeat the adjustment until =0 to compensate for the horizontal angle deviation.

[0044] Helium-neon lasers have extremely high monochromaticity, stability and coherence, and are often used as interference light sources. However, the output power of helium-neon lasers is low, and they are easily affected by environmental disturbances during long-distance transmission, resulting in poor results for laser liquid surface interferometry when measuring long-distance horizontal angles. Lasers with a wavelength of 1550nm have the advantages of low transmission loss, strong resistance to environmental interference, excellent beam collimation, and safety for human eyes, making them suitable for long-distance transmission. Therefore, a long-distance horizontal angle measurement method based on displacement bias is used to replace the laser liquid surface interferometry method. Figure 3 As shown, on the basis of the absolute horizontal alignment that has been established, the hanging mirror 13 is withdrawn in the transmission direction of the measuring light beam, and a dichroic mirror 14, a pinhole aperture 15, and a PSD position sensitive detector 16 are set, wherein the PSD position sensitive detector 16 is installed on a displacement stage 17. A 1550nm infrared incoherent laser is used as a collimated detection laser and shares an optical path with the absolute horizontal alignment to construct a long-distance absolute horizontal laser alignment based on collimated detection, and the PSD position sensitive detector 16 is used to identify the beam position. The distance between the PSD position sensitive detector 16 and the beam splitter 5 is changed within 50m by moving the displacement stage 17, thereby realizing long-distance horizontal angle measurement. The specific steps are as follows:

[0045] S1, withdraw the hanging mirror 13, place the dichroic mirror 14 and the pinhole aperture 15 in sequence along the transmission direction of the measuring beam, and install the PSD position sensitive detector 16 on the translation stage 17, which is the large-scale baseline guide rail slide;

[0046] S2, turn on the 1550nm infrared incoherent light source 2;

[0047] S3, the measuring light beam passes through the dichroic mirror 14, the helium-neon laser returns, and interferes with the helium-neon laser reflected by the horizontal liquid surface, which is used to measure the horizontal angle of the measuring light beam; the infrared incoherent laser is transmitted and hits the PSD position sensitive detector 16 through the small-diameter aperture 15;

[0048] S4. According to the change of the spot position of the PSD position sensitive detector 16 and the moving distance of the translation stage 17, the horizontal deflection angle of the translation stage 17 is calculated to achieve long-distance horizontal angle measurement.

[0049] like Figure 4 and Figure 5 As shown, the calculation formula of the horizontal deflection angle of the translation stage 17 is as follows:

[0050] If the light spot received by the PSD position sensitive detector 16 changes from position 0 to position 1 in the horizontal direction,

[0051]

[0052] Among them, on the PSD position sensitive detector 16, the coordinates of position 0 are , the coordinates of position 1 are , is the distance that the PSD position sensitive detector 16 moves when driven by the translation stage 17, is the horizontal tilt angle of the translation stage 17.

[0053] Only the preferred embodiments of the present invention are described in detail above, but the present invention is not limited to the above embodiments. Various changes can be made within the knowledge scope of ordinary technicians in this field without departing from the purpose of the present invention, and various changes should be included in the protection scope of the present invention.

Claims

1. An absolute horizontal alignment measuring device, characterized in that: The measuring device comprises a coherent light source, an incoherent light source, a beam splitter, a collimator, a horizontal liquid level standard, a right-angle prism and a CCD photoelectric detector. The coherent light source and the incoherent light source are connected to the input end of the collimator through a two-in-one optical fiber coupler. A two-dimensional adjustable base is arranged below the collimator. The optical path output end of the collimator is connected to the optical path input end of the beam splitter. The first optical path output end of the beam splitter is connected to the input end of the right-angle prism. The second optical path output end of the beam splitter is connected to the horizontal liquid level standard. The output end of the right-angle prism is connected to the detection input end of the CCD photoelectric detector through an achromatic lens and a plano-convex lens in sequence. The CCD photoelectric detector is connected to a computer.

2. The absolute horizontal alignment measuring device according to claim 1, characterized in that: The coherent light source is a helium-neon coherent laser with a wavelength of 633 nm.

3. The absolute horizontal alignment measuring device according to claim 1, characterized in that: The incoherent light source is an infrared incoherent laser with a wavelength of 1550 nm.

4. The absolute horizontal alignment measuring device according to claim 1, characterized in that: The focal length of the objective lens of the collimator is 500 mm, and the aperture of the objective lens is 50 mm.

5. A method for measuring an absolute horizontal alignment of the device according to any one of claims 1 to 4, characterized in that: Taking the horizontal liquid surface as the absolute horizontal reference, the plane interferometry method is used to establish the interference fringes between the horizontal liquid surface and the target mirror using coherent laser to achieve the measurement of the horizontal alignment or tilt angle; On the basis of absolute horizontal alignment measurement, a position sensitive detector is used to measure the relative position and angular relationship between the coaxial coherent laser and the incoherent laser beam. The long-distance horizontal alignment measurement is achieved by the change of the position of the incoherent laser on the position sensitive detector at a long distance.

6. The absolute horizontal alignment measurement method according to claim 5, characterized in that: The target mirror includes a hanging mirror or a flat crystal.

7. The absolute horizontal alignment measurement method according to claim 5, characterized in that: The planar interferometry method includes Fizeau interferometry, Tyemann interferometry or digital interferometry.

8. The absolute horizontal alignment measurement method according to claim 5, characterized in that: A hanging mirror is arranged in the transmission direction of the measuring light beam of the measuring device, and the horizontal liquid level standard and the hanging mirror are used as independent absolute horizontal references. The specific steps are as follows: S1. Set the hanging mirror on the same measuring beam transmission path of the measuring device, turn on the coherent light source to demodulate the interference pattern formed by the coherent laser reflected by the horizontal liquid surface and the self-leveling suspended parallel plane reflector, and obtain the angle between the two at this time. ; S2. Rotate the parallel plane mirror 180° and demodulate the interference pattern formed by the coherent laser reflected by the horizontal liquid surface and the self-leveling suspended parallel plane mirror to obtain the angle between the two at this time. ; S3. Obtain the absolute zero position of the measuring beam relative to the horizontal liquid surface , adjust the two-dimensional adjustable base so that the measuring beam is absolutely horizontal.

9. The absolute horizontal alignment measurement method according to claim 5, characterized in that: The specific steps of measuring the angle of the long-distance horizontal directrix are as follows: S1. A dichroic mirror, a pinhole aperture, and a PSD position sensitive detector are sequentially arranged along the transmission direction of the measuring beam of the measuring device, and the spacing of the PSD position sensitive detector is adjusted by a displacement area; S2, turn on the incoherent light source, the measuring light beam passes through the dichroic mirror, the coherent laser returns, and interferes with the coherent laser reflected by the horizontal liquid surface, which is used to measure the horizontal deviation angle of the measuring light beam; the incoherent laser is transmitted and hits the PSD position sensitive detector through the small diameter aperture; S3. According to the change of the spot position on the PSD position sensitive detector and the moving distance of the translation stage, the horizontal deflection angle of the translation stage is calculated to achieve long-distance horizontal angle measurement.

10. The absolute horizontal alignment measurement method according to claim 9, characterized in that: The calculation formula of the horizontal deflection angle of the translation stage is as follows: If the light spot received by the PSD position sensitive detector changes from position 0 to position 1 in the horizontal direction: ； Among them, on the PSD position sensitive detector, the coordinates of position 0 are , the coordinates of position 1 are , is the distance that the PSD position sensitive detector moves driven by the translation stage, is the horizontal tilt angle of the translation stage (17).

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