CN111174735A - Two-dimensional straightness and linear displacement simultaneous measurement interference device and measurement method - Google Patents
Two-dimensional straightness and linear displacement simultaneous measurement interference device and measurement method Download PDFInfo
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- CN111174735A CN111174735A CN201911343035.4A CN201911343035A CN111174735A CN 111174735 A CN111174735 A CN 111174735A CN 201911343035 A CN201911343035 A CN 201911343035A CN 111174735 A CN111174735 A CN 111174735A
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
- G01B11/00—Measuring arrangements characterised by the use of optical techniques
- G01B11/26—Measuring arrangements characterised by the use of optical techniques for measuring angles or tapers; for testing the alignment of axes
- G01B11/27—Measuring arrangements characterised by the use of optical techniques for measuring angles or tapers; for testing the alignment of axes for testing the alignment of axes
- G01B11/272—Measuring arrangements characterised by the use of optical techniques for measuring angles or tapers; for testing the alignment of axes for testing the alignment of axes using photoelectric detection means
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
- G01B11/00—Measuring arrangements characterised by the use of optical techniques
- G01B11/02—Measuring arrangements characterised by the use of optical techniques for measuring length, width or thickness
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Abstract
The invention relates to the technical field of optics, in particular to a two-dimensional straightness and linear displacement simultaneous measurement interference device and a measurement method, which are applied to straightness error detection and linear displacement measurement of a precision positioning platform, wherein collimated light beams emitted by a laser pass through a beam expanding system, central light beams are received by a baffle, hollow light beams which are not shielded by the baffle are divided into two parts by a light splitting plate, one part is reference light, the reference light passes through a quarter-wave plate and then enters a reflector, then returns to the original path, passes through the quarter-wave plate and then passes through the light splitting plate to be transmitted, and then passes through a polaroid, and the transmission direction of the polaroid forms an angle of 45 degrees with the horizontal direction; the other part is measuring light, the measuring light passes through the quarter-wave plate after passing through the transmission part of the light splitting plate and then passes through the conical lens to generate a corner, the corner is incident to the conical surface reflector and then returns to the original path, the reflecting light passes through the conical lens and the quarter-wave plate again to be reflected, and then the reflecting light passes through the polaroid to interfere with the reference light.
Description
Technical Field
The invention relates to the technical field of optics, in particular to a device and a method for simultaneously measuring two-dimensional straightness and linear displacement, which are applied to straightness error detection and linear displacement measurement of a precision positioning platform.
Background
The development of a batch of precise, high-speed, high-efficiency and flexible numerical control machine tools, basic manufacturing equipment and integrated manufacturing systems is one of the subjects of 'Chinese manufacture 2025', and has become a key research object in the manufacturing industry. At present, the displacement control precision in various precision positioning devices is generally in the nanometer level, and in systems or equipment relating to precision positioning platforms, such as high-performance precision numerical control machine tools, three-coordinate measuring machines and the like, the displacement measurement precision reaches a few nanometers, even below 1 nanometer. Therefore, high-precision displacement and angle detection is an important means for ensuring the machining precision.
At present, a multi-degree-of-freedom detection method mostly adopts a measurement method based on laser collimation and laser interference, wherein the method based on laser collimation utilizes light spot position information received by a photoelectric detector to acquire displacement information. The system utilizes a differential plane interferometer, combines the combination of wedge prism and wedge surface reflection to form a four-beam system with geometric space symmetry, and utilizes a phase meter with the resolution of 2 pi/3600 to realize the linearity error detection with the measurement resolution reaching the nanometer level. However, the laser interferometry is generally only capable of measuring one geometric quantity, and is not suitable for simultaneous measurement with multiple degrees of freedom.
The prior art also relates to a measuring method of two-degree-of-freedom errors based on laser interference, for example, a chinese patent application with application number 201910056987.1 discloses a scheme called a "micro-roll angle and straightness accuracy synchronous high-precision measuring interferometer and measuring method". However, this scheme is a detection of errors in two degrees of freedom achieved at an increased complexity of the optical path system, and there is no effective optical path adjustment scheme yet.
Disclosure of Invention
The invention aims to provide a device and a method for simultaneously measuring interference of two-dimensional straightness and linear displacement, which can accurately and effectively simultaneously measure the two-dimensional straightness and the linear displacement and can obtain the measurement precision of nanometer-scale straightness errors and micron-scale displacement errors.
In order to solve the technical problems, the technical scheme adopted by the invention is as follows: a two-dimensional straightness and linear displacement simultaneous measurement interference device is characterized in that after collimated light beams emitted by a laser pass through a beam expanding system, central light beams are received by a baffle, hollow light beams which are not shielded by the baffle are divided into two parts by a light splitting plate, one part of the hollow light beams pass through a quarter-wave plate and then enter a reflector and return in the original path, then pass through the quarter-wave plate and then pass through the light splitting plate to be transmitted, then pass through a polaroid, the polaroid forms 45 degrees with the horizontal direction, the light beams are diverged after passing through a concave lens, and the light beams are imaged to a photoelectric detector; the aperture beam passes through the light splitting plate, the transmission part of the aperture beam passes through the quarter-wave plate and then passes through the conical lens to generate a corner, the corner is incident to the conical surface reflector and then returns to the original path, the aperture beam passes through the conical lens and the quarter-wave plate to be reflected again, the transmission direction of the aperture beam forms 45 degrees with the horizontal direction after passing through the polaroid, and then the aperture beam passes through the concave lens to be imaged on the photoelectric detector.
Preferably, the cone angle of the conical lens is 170-179 degrees.
Preferably, the laser may be a He — Ne laser, a solid laser, or a semiconductor laser.
In order to solve the technical problems, the technical scheme adopted by the invention is as follows: a method for simultaneously measuring two-dimensional straightness and linear displacement is characterized by comprising the following steps: emergent light of the laser is a collimated light beam; the collimated light beam passes through a beam expanding system, the diameter of the light beam is increased, the central light beam is received by a baffle, the rest of the collimated light beam is called as a hollow light beam which is not shielded, the hollow light beam is divided into two parts after passing through a light splitting plate, the reflected light is a reference light beam, the polarization state is vertical polarized light, the circular polarized light is changed into a circular polarization state after passing through a quarter-wave plate, the circular polarized light is incident to a reflector and returns to the original path, the horizontal polarized light is changed into horizontal polarized light after passing through the quarter-wave plate again, the polarized light is transmitted after passing through the light splitting plate, the transmission direction of the polarized light and the horizontal direction of the polarized light form 45 degrees after passing through a; the hollow light beam passes through the light splitting plate, the transmission part is a measuring light beam, the polarization state is horizontal polarization light, the hollow light beam is changed into a circular polarization state after passing through the quarter-wave plate, the circular polarization state passes through the conical lens, the propagation direction of the light beam generates a certain turning angle, the light beam is incident to the conical surface reflector and returns to the original path, the circular polarization state passes through the conical lens and the quarter-wave plate again, the polarization state is changed into a vertical polarization state, the light beam is reflected after passing through the light splitting plate, the transmission direction of the light beam forms 45 degrees with the horizontal direction after passing through the polaroid, and the light beam is imaged to the photoelectric detector after passing through the concave.
Preferably, the reference beam and the measuring beam interfere at the photodetector; the photoelectric receiver is an area array CCD or two linear array CCDs arranged in a cross way; the concave lens functions to image the interference light on the photodetector.
The invention achieves the following beneficial effects: the interference device and the measuring method for simultaneously measuring the two-dimensional straightness and the linear displacement can simultaneously measure three geometric displacements of horizontal straightness, vertical straightness and linear displacement; meanwhile, the influence of environmental factors on linear displacement can be ignored, the method is suitable for complex detection environments, the structure is simple, and the measurement stroke and the measurement range are large.
Drawings
FIG. 1 is a diagram of an optical path system of an interference device for simultaneous measurement of two-dimensional straightness and linear displacement;
FIG. 2 is a schematic diagram of the light path of a light beam propagating in a conical lens;
FIG. 3 is a diagram of initial interference fringes;
FIG. 4 shows an interference fringe pattern after the conical lens is displaced in the direction of the optical axis;
FIG. 5 is a schematic diagram of an interference fringe pattern after a displacement of a conical lens in a direction perpendicular to the optical axis;
FIG. 6 is an interference pattern with a horizontal linearity shift of 50 microns and a vertical linearity shift of 50 microns perpendicular to the optical axis;
fig. 7 shows the principle of measurement of linear displacement in the direction of the optical axis.
Detailed Description
The invention is further described below with reference to the accompanying drawings. The following examples are only for illustrating the technical solutions of the present invention more clearly, and the protection scope of the present invention is not limited thereby.
Referring to fig. 1, a two-dimensional linearity and linear displacement simultaneous measurement interference device, a laser 1 emits a collimated light beam, the collimated light beam passes through a beam expanding system 2, a central light beam is received by a baffle 3, a hollow light beam which is not blocked by the baffle 3 is divided into two parts by a light splitting plate 4, one part of the hollow light beam passes through a quarter-wave plate 8, then enters a reflector 9 and returns to the original path, passes through the quarter-wave plate 8, then passes through the light splitting plate 4 to be transmitted, then passes through a polarizer 11, the polarizer 11 forms a 45 degree angle with the horizontal direction, passes through a concave lens 12 to be diverged, and the light beam is imaged to a photoelectric detector 13; the aperture beam passes through the light splitting plate 4, the transmission part of the aperture beam passes through the quarter-wave plate 5 and then passes through the conical lens 6 to generate a corner, the corner is incident on the conical surface reflector 7 and then returns to the original path, the aperture beam passes through the conical lens 6 and the quarter-wave plate 5 to be reflected again, the aperture beam passes through the polaroid 11, the transmission direction of the aperture beam and the horizontal direction form a 45-degree angle, and then the aperture beam passes through the concave lens 12 and is imaged on the photoelectric detector 13.
The cone angle of the conical lens 6 is 170-179 degrees.
The laser 1 may be a He — Ne laser, a solid laser, or a semiconductor laser.
A two-dimensional straightness and linear displacement simultaneous measurement method, emergent light of a laser 1 is a collimated light beam; the collimated light beam passes through the beam expanding system 2, the light beam diameter is enlarged, the central light beam is received by the baffle 3, the rest of the collimated light beam is called as a hollow light beam which is not shielded, the hollow light beam is divided into two parts after passing through the light splitting plate 4, the reflected light is a reference light beam, the polarization state is vertical polarization light, the circular polarization state is changed after passing through the quarter-wave plate 8, the circular polarization state is incident to the reflector 9 and returns to the original path, the horizontal polarization light is changed after passing through the quarter-wave plate 8 again, the polarization light is transmitted after passing through the light splitting plate 4, the polarization direction of the polarization light is 45 degrees with the horizontal direction after passing through the polarizing plate 11, the light beam is dispersed after passing through the concave lens; the hollow light beam passes through the light splitting plate 4, the transmission part of the hollow light beam is a measuring light beam, the polarization state is horizontal polarization light, the hollow light beam is changed into a circular polarization state after passing through the quarter-wave plate 5, the circular polarization state passes through the conical lens 6, the propagation direction of the light beam generates a certain turning angle, the light beam enters the conical surface reflector 7 and returns back, the polarization state of the light beam passes through the conical lens 6 and the quarter-wave plate 5 again, the vertical polarization state is changed, the light beam is reflected after passing through the light splitting plate 4, the transmission direction of the light beam passes through the polarizing plate 1, the transmission direction and the horizontal direction of the light beam form 45 degrees, and the light beam passes through.
The reference beam and the measuring beam interfere on the photodetector 13; the photoelectric receiver is an area array CCD or two linear array CCDs arranged in a cross way; the concave lens 12 functions to image the interference light on the photodetector.
The photodetector may be an area array CCD or two line CCD arrays arranged in a cross, see fig. 3 and 4.
When the conical lens is linearly displaced in the optical axis direction, the interference fringes appear as 'invagination' or 'spitting out', and refer to fig. 5, the interference fringe pattern after the displacement in the optical axis direction is 7.5 micrometers; if the conical lens generates linear displacement perpendicular to the optical axis, the interference fringes show that the movement direction of the conical lens is changed towards or away from the conical lens, and the interference fringes are symmetrically distributed, the symmetrical axis is along the displacement change direction, and fig. 6 shows an interference pattern with the horizontal linearity displacement of 50 micrometers and the vertical linearity displacement of 50 micrometers in the direction perpendicular to the optical axis.
The principle of the straightness measurement perpendicular to the optical axis direction is described in detail below:
FIG. 2 is a schematic diagram of the propagation of a Beam through a wedge-angle prism (arbitrary cross section through the optical axis), where α is the wedge angle and β is the refraction angle. at the beginning of the measurement, the optical path of the Beam is shown by a dashed line, and if the wedge-angle prism is displaced by d in the x direction, the left Beam1 is displaced by d relative to the propagation path of the Beam as shown by a solid line, and the right Beam2 is displaced by d inward, since the total path of the Beam propagation does not change, but the Beam1 propagates within the wedge-angle prism at an increased distance AA, the distance of the Beam propagating in air is reduced by BB, the wedge-angle prism is made of k9 glass with a refractive index of 1.516, and the refractive index of air is about 1, and the optical path of the Beam1 is increased, and the Beam2 propagates within the wedge-angle prism at a decreased distance and an increased distance of the Beam2, the Beam2 is decreased, and the absolute change of the Beam1 is equal in sign.
Assuming that L is the variation of the path of the light Beam1 in the wedge prism, it can be obtained:
since the Beam1 passes through the wedge angle prism 2 times in sequence, the total optical path difference can be expressed as:
ΔL＝2L(n-1)＝2(n-1)dtanα (2)
where n represents the index of refraction of the wedge angle prism and 1 represents the index of refraction of air. The relationship between the optical path change and the phase difference Δ Φ can be expressed as:
where λ is the wavelength of the incident light. Thus, it is possible to obtain:
when α is 2 °, the wavelength is 632.8nm, and the resolution of the phase meter is 2 pi/720, the minimum resolution of the linearity d measured from the change in the interference fringe of Beam1 is about 24nm, and since the interference fringes are symmetrically distributed, the symmetrical interference fringes change equally when the linearity is shifted, and therefore, the symmetrical fringes can be detected, and the resolution can be doubled to 12 nm.
The measurement principle of the linear displacement in the optical axis direction is described in detail below:
referring to fig. 7, when the conical lens (6) is displaced in the optical axis direction, the conical lens (6) starts at the position of the broken line, and the solid line is the position after the displacement in the optical axis direction. The path of the light beam is changed from an MK section to an MN section, and the rest light paths are overlapped or parallel with the original light path.
Therefore, the optical path length thereof varies as follows:
ΔL′＝1*(LMk-LMN)＝LMK*(1-cosγ) (5)
where 1 is the refractive index of air, γ is α - β, and is the deflection angle of the light beam after passing through the conical lens, and when α is 2 °, the wavelength is 632.8nm, and the resolution of the phase meter is 2 pi/720, the resolution of the linear displacement along the optical axis direction is about 2.9 μm.
Compared with the invention patent with the publication number of CN201910056987.1, the optical system used by the invention is simpler, and can realize the detection of the displacement error of the two-dimensional linearity at the nanometer level and the detection of the displacement of the linear linearity at the micrometer level. The method is suitable for online detection of two-dimensional straightness errors of various precision positioning platforms.
The above is only a preferred embodiment of the present invention, and it should be noted that, for those skilled in the art, several modifications and variations can be made without departing from the technical principle of the present invention, and these modifications and variations should also be regarded as the protection scope of the present invention.
Claims (5)
1. The utility model provides a two-dimentional straightness accuracy and linear displacement simultaneous measurement interference device which characterized in that: after collimated light beams emitted by the laser (1) pass through the beam expanding system (2), central light beams are received by the baffle (3), hollow light beams which are not shielded by the baffle (3) are divided into two parts by the light splitting plate (4), one part of the hollow light beams pass through the quarter-wave plate (8) and then enter the reflector (9) and then return to the original path, pass through the quarter-wave plate (8) and then pass through the light splitting plate (4) to be transmitted, then pass through the polaroid (11), the polaroid (11) forms 45 degrees with the horizontal direction, the light beams are diffused after passing through the concave lens (12), and the light beams are imaged to the photoelectric detector (13); the aperture beam passes through the light splitting plate (4), the transmission part of the aperture beam passes through the quarter-wave plate (5), then passes through the conical lens (6) to generate a corner, the corner is incident on the conical surface reflector (7), then the original path returns, the aperture beam passes through the conical lens (6) and the quarter-wave plate (5) again to be reflected, then passes through the polarizing plate (11), the transmission direction of the aperture beam forms 45 degrees with the horizontal direction, and then passes through the concave lens (12), and the beam is imaged onto the photoelectric detector (13).
2. The simultaneous two-dimensional straightness and linear displacement measuring interferometer of claim 1, wherein: the cone angle of the conical lens (6) is 170-179 degrees.
3. The simultaneous two-dimensional straightness and linear displacement measuring interferometer of claim 1, wherein: the laser (1) may be a He-Ne laser, a solid-state laser, or a semiconductor laser.
4. A method for simultaneously measuring two-dimensional straightness and linear displacement is characterized by comprising the following steps: emergent light of the laser (1) is a collimated light beam; the collimated light beam passes through the beam expanding system (2), the beam diameter is enlarged, the central light beam is received by the baffle (3), the rest of the collimated light beam is called as a hollow light beam which is not shielded, the hollow light beam is divided into two parts after passing through the light splitting plate (4), the reflected light is a reference light beam, the polarization state is vertical polarized light, the hollow light beam is changed into a circular polarization state after passing through the quarter-wave plate (8), the circular polarization state is incident to the reflector (9) and then returns to the original path, the horizontal polarized light is changed into horizontal polarized light after passing through the quarter-wave plate (8), the polarized light is transmitted after passing through the light splitting plate (4), and then passes through the polaroid (11), and the transmission direction and the; the transmission part of the hollow beam is a measuring beam after passing through the light splitting plate (4), the polarization state is horizontal polarized light, the hollow beam is changed into a circular polarization state after passing through the quarter-wave plate (5), the circular polarization state is changed into a circular polarization state after passing through the conical lens (6), the propagation direction of the beam generates a certain rotation angle, the circular polarization state is incident to the conical surface reflector (7) and returns to the original path, the circular polarization state passes through the conical lens (6) and the quarter-wave plate (5), the polarization state is changed into a vertical polarization state after passing through the light splitting plate (4), the vertical polarization state is reflected, the transmission direction of the beam passes through the polarizing plate (11), the polarization direction of the polarizing plate and the horizontal direction form 45 degrees after passing through the polarizing plate (11), the reference beam and the measuring beam are interfered, and.
5. The simultaneous two-dimensional straightness and linear displacement measuring method according to claim 4, wherein: the reference beam and the measuring beam interfere on a photodetector (13); the photoelectric receiver is an area array CCD or two linear array CCDs arranged in a cross way; the concave lens (12) is used for imaging the interference light on the photoelectric detector.
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| CN201911343035.4A CN111174735A (en) | 2019-12-24 | 2019-12-24 | Two-dimensional straightness and linear displacement simultaneous measurement interference device and measurement method |
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| CN201911343035.4A CN111174735A (en) | 2019-12-24 | 2019-12-24 | Two-dimensional straightness and linear displacement simultaneous measurement interference device and measurement method |
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN112504154A (en) * | 2020-11-02 | 2021-03-16 | 南京信息工程大学滨江学院 | Large-size support structure deformation measuring device and measuring method based on optical path |
| CN112525082A (en) * | 2020-11-26 | 2021-03-19 | 合肥工业大学 | Device and method for simultaneously detecting positioning accuracy and straightness of linear displacement table |
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2019
- 2019-12-24 CN CN201911343035.4A patent/CN111174735A/en not_active Withdrawn
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN112504154A (en) * | 2020-11-02 | 2021-03-16 | 南京信息工程大学滨江学院 | Large-size support structure deformation measuring device and measuring method based on optical path |
| CN112504154B (en) * | 2020-11-02 | 2022-06-03 | 南京信息工程大学滨江学院 | Large-size support structure deformation measuring device and measuring method based on optical path |
| CN112525082A (en) * | 2020-11-26 | 2021-03-19 | 合肥工业大学 | Device and method for simultaneously detecting positioning accuracy and straightness of linear displacement table |
| CN112525082B (en) * | 2020-11-26 | 2022-04-29 | 合肥工业大学 | Device and method for simultaneously detecting positioning accuracy and straightness of linear displacement table |
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