CN103644849B - A kind of three dimensional grating displacement measurement system surveying vertical displacement - Google Patents

Abstract

A three-dimensional grating displacement measurement system capable of measuring vertical displacement relates to a grating displacement measurement system; the measurement system includes a single-frequency laser light source, a light splitting component, a polarization beam splitter prism, a quarter-wave plate of a measuring arm, and a refractive element of the measuring arm , a reference arm quarter-wave plate, a reference arm refraction element, a two-dimensional reflective reference grating, photoelectric detection and signal processing components, and a two-dimensional reflective measurement grating; the two-dimensional reflective measurement grating and the two-dimensional reflective reference The surface topography of the grating is the same, the x-direction period and the y-direction period of the two-dimensional reflective measuring grating and the two-dimensional reflective reference grating are both d; the x-direction refraction angle and the y-direction The refraction angles are all θ _i , and satisfy 2dsinθ _i =±mλ; the present invention can not only measure the linear displacement along the three directions of x-axis, y-axis and z-axis at the same time, but also the z-direction displacement range of the system compared with the prior art has been greatly expanded.

Description

A three-dimensional grating displacement measuring system capable of measuring vertical displacement

technical field

A three-dimensional grating displacement measuring system capable of measuring vertical displacement relates to a grating displacement measuring system, in particular to a three-dimensional grating displacement measuring system capable of measuring vertical displacement.

Background technique

Grating displacement measurement technology first originated in the 19th century and has developed rapidly since the 1950s. At present, the grating displacement measurement system has become a typical displacement sensor and is widely used in many electromechanical devices. Due to the advantages of high resolution, high precision, low cost, and low environmental sensitivity, the grating displacement measurement system has not only been widely used in industry and scientific research, but also studied by many domestic and foreign scholars.

Lithography machine is the core equipment for producing semiconductor chips. The ultra-precision workpiece table is the core subsystem of the lithography machine, which is used to carry the substrate and complete the high-speed ultra-precision movement in the process of loading, exposing, changing the stage, and unloading the film. The ultra-precision workpiece table has the characteristics of high speed, high acceleration, multiple degrees of freedom, large stroke, and ultra-precision. Dual-frequency laser interferometer is widely used for displacement measurement of ultra-precision workpiece table because of its advantages of high precision and large range. However, in recent years, the process level of semiconductor chip manufacturing has been continuously improved: in 2010, the processing of semiconductor chips has adopted a 32nm line width process; at the end of 2011, CPU chips with a 22nm line width have also been sold on the market. The ever-increasing level of semiconductor chip processing puts forward higher requirements for the resolution and accuracy of ultra-precision workpiece table displacement measurement. The dual-frequency laser interferometer has poor environmental sensitivity, takes up a large space, and has a multi-degree-of-freedom measurement structure. Complex and expensive problems are difficult to meet new measurement requirements.

In order to solve the above problems, relevant companies and many scholars in the field of ultra-precision measurement at home and abroad have conducted a lot of research, and the research results have been disclosed in many patents and papers. The patent US7,483,120B2 (published on November 15, 2007) of the Dutch ASML company discloses a planar grating measurement system and layout scheme applied to the ultra-precision workpiece table of the lithography machine. The measurement system mainly uses a two-dimensional planar grating The horizontal large stroke displacement of the workpiece table is measured with the reading head, and the vertical displacement of the workpiece table can be measured by a separately arranged height sensor, but the use of multiple sensors will make the structure of the ultra-precision workpiece table complicated and limit the displacement measurement accuracy . Japanese scholar Gao Wei proposed a three-dimensional grating displacement measurement system based on the principle of diffraction interference in the paper "Asub-nanometric three-axis surface encoder with short-period planargratings for stage motion measurement. Precision Engineering 36 (2012) 576-585." Linear displacement in one direction, but when the system measures the linear displacement in the z direction, the interference area between the measuring light and the reference light will become smaller, so the range of the linear displacement in the z direction of the system is limited by the diameter of the beam, and it is impossible to realize z The measurement of the linear displacement of the large stroke in the direction. The patent CN102937411A (disclosure date: February 20, 2013) of Tsinghua University Zhu Yu et al. discloses a dual-frequency grating interferometer displacement measurement system, which can simultaneously measure linear displacements in both horizontal and vertical directions, and uses The dual-frequency laser is used as the light source to improve the anti-interference ability of the signal, but the range of the linear displacement in the vertical direction of the system is also limited by the size of the beam diameter, and it is still impossible to measure the linear displacement of the large stroke in the vertical direction, and the system uses One-dimensional and two-dimensional reflective measuring gratings can only measure linear displacement in two directions. In the paper "DisplacementMeasurementofPlanarStagebyDiffractionPlanarEncoderinNanometerResolution.I2MTC (2012) 894-897." published by FanKuang-Chao and others at National Taiwan University, a two-dimensional planar grating displacement measurement device with nanoscale resolution can be measured in two horizontal directions. Linear displacement, but it cannot measure the linear displacement in the vertical direction, nor can it meet the displacement measurement requirements in the vertical direction of the ultra-precision workpiece table.

Contents of the invention

In order to solve the above problems, the object of the present invention is to provide a three-dimensional grating displacement measuring system capable of measuring vertical displacement. Compared with the prior art, the z-direction displacement range of the system has been greatly expanded.

The purpose of the present invention is achieved like this:

A three-dimensional grating displacement measurement system capable of measuring vertical displacement, comprising a single-frequency laser light source, a light splitting component, a polarization beam splitter prism, a quarter-wave plate of a measuring arm, a refracting element of a measuring arm, a quarter-wave plate of a reference arm, Reference arm refraction element, two-dimensional reflective reference grating, photoelectric detection and signal processing components and two-dimensional reflective measurement grating;

The two-dimensional reflective measuring grating and the two-dimensional reflective reference grating have the same surface topography, the x-direction period and the y-direction period of the two-dimensional reflective measuring grating are both d; the x-direction period and the y-direction period of the two-dimensional reflective reference grating are d The directional periods are all d; the refraction angles in the x direction and y direction of the refraction element of the measuring arm are both θ _i , and the refraction angles in the x direction and y direction of the reference arm refraction element are both θ _i , and satisfy 2dsinθ _i =±mλ, where λ is the wavelength of the single-frequency laser source, and m is the diffraction order;

The single-frequency laser light emitted by the single-frequency laser light source is divided into four beams of parallel light beams with equal light intensity through the beam splitter, wherein the propagation direction of the two beams is parallel to the xoy plane, and the propagation direction of the other two beams is parallel to the xoz plane. The beam of parallel light passes through the polarization beam splitter and is divided into the measurement light whose propagation direction is deflected by 90 degrees and the reference light which propagates along the original direction. The polarization direction of the measurement light is perpendicular to the polarization direction of the reference light;

After the four parallel beams of measuring light pass through the quarter-wave plate of the measuring arm whose fast axis direction is 45 degrees to the polarization direction of the measuring light, they are all deflected by the refracting element of the measuring arm. Two of the deflected four beams of measuring light The propagation direction of the light is parallel to the yoz plane, and the propagation direction of the other two beams is parallel to the xoz plane. The two beams of measurement light whose propagation direction is parallel to the yoz plane are incident on the two-dimensional reflective measurement grating and are diffracted into +m in the y direction respectively. order diffraction measurement light and -m order diffraction measurement light, two beams of measurement light whose propagation direction is parallel to the xoz plane are incident on the two-dimensional reflective measurement grating and are diffracted into +m order diffraction measurement light and -m order diffraction measurement light in the x direction respectively Measuring light, the four beams of diffracted measuring light propagate along the opposite directions of the respective incident light propagation directions, and pass through the refraction element of the measuring arm, the quarter-wave plate of the measuring arm and the polarization beam splitter again, and then enter the photoelectric detection and signal processing components ;

After the four beams of parallel light of the reference beam pass through the reference arm quarter-wave plate whose fast axis direction is 45 degrees to the polarization direction of the reference beam, they are all deflected by the reference arm refraction element, and two of the deflected four beams of reference light The propagation direction of the light is parallel to the xoy plane, the propagation direction of the other two beams is parallel to the xoz plane, and the two reference beams with the propagation direction parallel to the xoy plane are incident on the two-dimensional reflective reference grating and are diffracted into +m in the y direction respectively order diffraction reference light and -m order diffraction reference light, two beams of reference light whose propagation direction is parallel to the xoz plane are incident on the two-dimensional reflective reference grating and are diffracted into +m order diffraction reference light and -m order diffraction in the x direction respectively Reference light, the four beams of diffracted reference light respectively propagate along the opposite directions of the respective incident light propagation directions, and pass through the reference arm refraction element, the reference arm quarter-wave plate and the polarization beam splitter again, and then enter the photoelectric detection and signal processing components ;

Two beams of diffracted measurement light in the x direction and two beams of diffracted reference light in the x direction form two groups of interference on the surface of the photoelectric detection and signal processing components, and two beams of diffracted measurement light in the y direction and two beams of diffracted reference light in the y direction And the surface of the signal processing part forms another two sets of interference; when the other components do not move and the two-dimensional reflective measurement grating moves along the x-axis, y-axis and z-axis, the photoelectric detection and signal processing parts output the x-direction, y-direction and z-axis respectively Direction of linear displacement.

In the above-mentioned three-dimensional grating displacement measuring system capable of measuring vertical displacement, the single-frequency laser light source is a semiconductor laser diode or a gas laser whose exit is terminated with an optical fiber.

In the above-mentioned three-dimensional grating displacement measurement system capable of measuring vertical displacement, the light-splitting component is one of the following four structures:

First, the beam-splitting component is composed of a collimating lens, a first non-polarizing beam splitting prism, a second non-polarizing beam splitting prism, a first right-angle reflecting prism, a third non-polarizing beam-splitting prism, and a second right-angle reflecting prism, and a single-frequency laser light source The emitted laser light is collimated by the collimator lens and then enters the first non-polarizing beam splitter prism and is divided into two beams of light with equal light intensity and perpendicular to each other. The transmitted light with the same light intensity and the reflected light with the propagation direction along the x direction, the transmitted light is reflected by the first right-angle reflective prism and propagates along the x direction, and the other beam propagates along the x direction and enters the third non-polarizing beam splitter prism to be divided into light intensities Equal transmitted light and reflected light with the propagation direction along the -y direction, and the reflected light is reflected by the second right-angle reflective prism and propagates along the x direction;

Second, the light splitting component is composed of a collimating lens, a two-dimensional transmission grating, a reflector, and an aperture stop. After being collimated by the straight lens, it enters the two-dimensional transmission grating and is diffracted. The ±1st-order diffracted light in the x-direction and y-direction is deflected by the mirror and passes through the aperture stop to form four beams of parallel outgoing light with equal light intensity. Other orders The diffracted light is filtered by the aperture stop;

Third, the spectroscopic component is composed of a collimating lens, a two-dimensional transmission grating, a lens, and an aperture stop. After the lens is collimated, it enters the two-dimensional transmission grating and is diffracted. The ±1st-order diffracted light in the x direction and y direction is deflected by the lens and passes through the aperture stop to form four beams of parallel outgoing light with equal light intensity. The other orders of diffraction The light is filtered by the aperture stop;

Fourth, the light splitting component is composed of a collimating lens, a two-dimensional transmission grating, a prism, and an aperture stop. The grating periods of the two-dimensional transmission grating in the x direction and the y direction are equal, and the laser light emitted by the single-frequency laser source is collimated. After the lens is collimated, it enters the two-dimensional transmission grating and is diffracted. The ±1st-order diffracted light in the x-direction and y-direction is deflected by the prism and passes through the aperture stop to form four beams of parallel outgoing light with equal light intensity. The other orders of diffraction The light is filtered by the aperture stop.

In the above-mentioned three-dimensional grating displacement measurement system capable of measuring vertical displacement, the refraction element of the measurement arm is one of the following four structures:

First, the refraction element of the measuring arm includes an aperture and a refraction mirror, and the two beams of parallel measuring light whose propagation direction is parallel to the yoz plane pass through the aperture and the refraction mirror, and the propagation directions are respectively deflected by ± _θi and incident Diffraction occurs to the two-dimensional reflective measuring grating, and the two beams of parallel measuring light whose propagation direction is parallel to the xoz plane pass through the diaphragm and the refracting mirror, and the propagation direction is respectively deflected by ± _θi and enters the two-dimensional reflective measuring grating Diffraction occurs;

Second, the refraction element of the measuring arm includes an aperture and a refraction prism, and the two beams of parallel measurement light whose propagation direction is parallel to the yoz plane pass through the aperture and the refraction prism, and the propagation directions are respectively deflected by ± _θi and incident on two Diffraction occurs on the two-dimensional reflective measuring grating, and the propagation direction of the two beams of parallel measuring light parallel to the xoz plane passes through the diaphragm and the refracting prism, and the propagation directions are respectively deflected by ± _θi and incident on the two-dimensional reflective measuring grating to undergo diffraction;

Thirdly, the refraction element of the measurement arm includes a diaphragm and a first refraction lens, and the propagation directions of the two parallel measuring lights whose propagation direction is parallel to the yoz plane pass through the diaphragm and the first refraction lens are respectively deflected by ±θ _i And incident to the two-dimensional reflective measurement grating for diffraction, the two beams of parallel measuring light whose propagation direction is parallel to the xoz plane pass through the diaphragm and the first refracting lens, and the propagation direction is respectively deflected by ± _θi and enters the two-dimensional reflective Diffraction occurs on the type measuring grating;

Fourth, the refraction element of the measuring arm includes a diaphragm and a second refraction lens, and the propagation direction of the two parallel measuring lights whose propagation direction is parallel to the yoz plane passes through the diaphragm and the second refraction lens, and their propagation directions are respectively deflected by ±θ _i And incident to the two-dimensional reflective measurement grating for diffraction, the two beams of parallel measuring light whose propagation direction is parallel to the xoz plane pass through the diaphragm and the second refraction lens, and the propagation direction is respectively deflected by ± _θi and enters the two-dimensional reflection Diffraction occurs on the formula measuring grating.

The reference arm refraction element is one of four structures adopted by the measurement arm refraction element.

The beneficial effects of the present invention are described as follows:

The measurement system uses a two-dimensional reflective measuring grating, a two-dimensional reflective reference grating, a measuring arm refracting element, a reference arm refracting element and a single-frequency laser light source satisfying the condition of _2dsinθi = ±mλ, ensuring that the four beams of diffracted measuring light are respectively Propagate along the opposite direction of the respective incident light propagation direction, so when the two-dimensional reflective measurement grating moves along the z-axis relative to the refraction element of the measurement arm, the spot positions of the four beams of diffracted measurement light on the surface of the photoelectric detection and signal processing components remain unchanged, and Because the relative positions of other components except the two-dimensional reflective measurement grating are always unchanged during the measurement, the spot positions of the four diffracted reference beams on the surface of the photoelectric detection and signal processing components are always unchanged, so in the two-dimensional reflective measurement When the grating moves along the z-axis relative to the refraction element of the measuring arm, the interference areas of the four sets of interference spots on the surface of the photoelectric detection and signal processing components remain unchanged, and the z-direction displacement range of the system is no longer limited by the size of the spot diameter, but depends on The coherence length of the light source. The light source of the present invention is a single-frequency laser light source. The coherence length of the single-frequency laser light source is generally above the order of centimeters, and can reach the order of meters or even kilometers. Therefore, the z-direction displacement range of the present invention can be extended To the order of meters or even kilometers, the measuring device developed by Japanese scholar Gao Wei in the prior art is the only device that can use a single measuring device to realize three-dimensional displacement measurement, but its z-direction displacement range only reaches 4mm, so the present invention The notable beneficial effect is that not only a grating measurement system capable of simultaneously measuring three-dimensional displacement is provided, but also the z-direction displacement range of the system is greatly expanded compared with the prior art.

Description of drawings

Fig. 1 is a structural schematic diagram of a three-dimensional grating displacement measuring system capable of measuring vertical displacement according to the present invention.

Fig. 2 is a schematic structural diagram of the first structure of the light splitting component of the present invention.

Fig. 3 is a sectional view in the xoz direction of the second structure of the light splitting component of the present invention.

Fig. 4 is a sectional view in the xoz direction of the third structure of the light splitting component of the present invention.

Fig. 5 is a sectional view in the xoz direction of the fourth structure of the light splitting component of the present invention.

Fig. 6 is a sectional view in the xoz direction of the first structure of the refraction element of the measuring arm of the present invention.

Fig. 7 is a sectional view in the xoz direction of the second structure of the refraction element of the measuring arm of the present invention.

Fig. 8 is a sectional view in the xoz direction of the third structure of the refraction element of the measuring arm of the present invention.

Fig. 9 is a sectional view in the xoz direction of the fourth structure of the refraction element of the measuring arm of the present invention.

In the figure: 1 single-frequency laser light source; 2 light-splitting components; 21 collimating lens; 22 first non-polarizing beam-splitting prism; 23 second non-polarizing beam-splitting prism; 24 first right-angle reflecting prism; 25 third non-polarizing beam-splitting prism; The second right-angle reflective prism; 27 two-dimensional transmission grating; 281 mirror; 282 lens; 283 prism; Diaphragm; 332 refraction mirror; 333 refraction prism; 334 first refraction lens; 335 second refraction lens; 34 reference arm quarter-wave plate; 35 reference arm refraction element; 36 two-dimensional reflective reference grating; 4 photoelectric detection And signal processing components; 5 two-dimensional reflective measurement grating.

detailed description

The specific embodiments of the present invention will be further described in detail below in conjunction with the accompanying drawings.

Specific embodiment one

The structure diagram of the three-dimensional grating displacement measurement system capable of measuring vertical displacement in this embodiment is shown in FIG. 1 . The measurement system includes a single-frequency laser light source 1, a light-splitting component 2, a polarization beam-splitting prism 31, a measurement arm quarter-wave plate 32, a measurement arm refraction element 33, a reference arm quarter-wave plate 34, and a reference arm refraction element 35. , a two-dimensional reflective reference grating 36, a photoelectric detection and signal processing component 4 and a two-dimensional reflective measurement grating 5;

The two-dimensional reflective measuring grating 5 and the two-dimensional reflective reference grating 36 have the same surface appearance, and the x-direction period and the y-direction period of the two-dimensional reflective measuring grating 5 are both d; the x-direction period of the two-dimensional reflective reference grating 36 is Both the direction cycle and the y direction cycle are d; the x-direction refraction angle and y-direction refraction angle of the measuring arm refraction element 33 are both _θi , and the x-direction refraction angle and y-direction refraction angle of the reference arm refraction element 35 are both θ _i , and satisfy 2dsinθ _i =±mλ, where λ is the wavelength of the single-frequency laser light source 1, and m is the diffraction order;

The single-frequency laser light emitted by the single-frequency laser light source 1 is divided into four beams of parallel light with equal light intensity through the light splitting component 2, wherein the propagation direction of the two beams of light is parallel to the xoy plane, and the propagation direction of the other two beams of light is parallel to the xoz plane. These four beams of parallel light are divided into measuring light deflected by 90 degrees in the propagation direction and reference light propagating along the original direction after passing through the polarization beam splitter 31, and the polarization direction of the measurement light is perpendicular to the polarization direction of the reference light;

After the four beams of parallel beams of measuring light pass through the quarter-wave plate 32 of the measuring arm whose fast axis direction is 45 degrees to the polarization direction of the measuring light, they are all deflected by the refracting element 33 of the measuring arm, and the deflected four beams of measuring light The propagation direction of the two beams of light is parallel to the yoz plane, the propagation direction of the other two beams of light is parallel to the xoz plane, and the two beams of measurement light whose propagation direction is parallel to the yoz plane are incident on the two-dimensional reflective measuring grating 5 and are diffracted into the y direction The +m-order diffraction measurement light and the -m-order diffraction measurement light, the two beams of measurement light whose propagation direction is parallel to the xoz plane are incident on the two-dimensional reflective measurement grating 5 and are diffracted into +m-order diffraction measurement light and - m-order diffracted measurement light, the four beams of diffracted measurement light respectively propagate along the opposite directions of the respective incident light propagation directions, and pass through the refraction element 33 of the measurement arm, the quarter-wave plate 32 of the measurement arm and the polarization beam splitter 31 again, and then enter To the photoelectric detection and signal processing unit 4;

After the four beams of parallel light beams of the reference light pass through the reference arm quarter-wave plate 34 whose fast axis direction is 45 degrees to the polarization direction of the reference beam, they are all deflected by the reference arm refraction element 35, and among the deflected four beams of reference light The propagation direction of the two beams of light is parallel to the xoy plane, the propagation direction of the other two beams of light is parallel to the xoz plane, and the two beams of reference light whose propagation direction is parallel to the xoy plane enter the two-dimensional reflective reference grating 36 and are diffracted into the y direction respectively The +m-order diffraction reference light and the -m-order diffraction reference light, the two beams of reference light whose propagation direction is parallel to the xoz plane are incident on the two-dimensional reflective reference grating 36 and are diffracted into the +m-order diffraction reference light and the +m-order diffraction reference light in the x direction respectively -m-order diffraction reference light, the four beams of diffraction reference light respectively propagate along the opposite direction of the propagation direction of the respective incident light, and pass through the reference arm refraction element 35, the reference arm quarter-wave plate 34 and the polarization beam splitter 31 again, and enter To the photoelectric detection and signal processing unit 4;

The two beams of diffraction measurement light in the x direction and the two beams of diffraction reference light in the x direction form two sets of interference on the surface of the photoelectric detection and signal processing component 4, and the two beams of diffraction measurement light in the y direction and the two beams of diffraction reference light in the y direction are in the photoelectric detection and signal processing component 4. The surface of the detection and signal processing part 4 forms another two groups of interference; when other components do not move and the two-dimensional reflective measuring grating 5 moves along the x-axis, y-axis and z-axis, the photoelectric detection and signal processing part 4 outputs the x-direction, Linear displacement in y-direction and z-direction.

In the three-dimensional grating displacement measurement system capable of measuring vertical displacement, the single-frequency laser light source 1 is a semiconductor laser diode.

Specific embodiment two

The difference between this embodiment and the first embodiment is that the single-frequency laser light source 1 is a gas laser whose output is connected to an optical fiber.

Specific embodiment three

The three-dimensional grating displacement measuring system capable of measuring vertical displacement in this embodiment has the same overall structure as that in Embodiment 1. Wherein, the three-dimensional specific structure of the light splitting component 2 is shown in FIG. 2 . This beam splitter 2 is made up of collimating lens 21, first non-polarization beam splitting prism 22, second non-polarization beam splitting prism 23, first right-angle reflective prism 24, the third non-polarization beam-splitter prism 25, second right-angle reflective prism 26, single The laser light emitted by the high-frequency laser light source 1 is collimated by the collimator lens 21 and then incident on the first non-polarizing beam splitter prism 22, where it is divided into two beams of light with equal light intensity and perpendicular propagation directions, one of which is incident to the second beam along the z direction. The non-polarizing beamsplitter prism 23 is divided into transmitted light with equal light intensity and reflected light whose propagation direction is along the x direction. The transmitted light is reflected by the first right-angle reflective prism 24 and propagates along the x direction, and another beam of light propagates along the x direction and is incident to the third The non-polarizing beam-splitting prism 25 is divided into transmitted light with equal light intensity and reflected light whose propagation direction is along the -y direction, and the reflected light is reflected by the second right-angle reflective prism 26 and propagates along the x direction.

Specific embodiment four

The three-dimensional grating displacement measuring system capable of measuring vertical displacement in this embodiment has the same overall structure as that in Embodiment 1. Wherein, the cross-sectional view of the light splitting component 2 in the xoz direction is shown in FIG. 3 . This spectroscopic component is made up of collimator lens 21, two-dimensional transmission grating 27, mirror 281, aperture diaphragm 29, and the grating period of described two-dimensional transmission grating 27x direction and y direction is equal, and the laser light emitted by single-frequency laser source 1 passes through After being collimated by the collimator lens 21, it enters the two-dimensional transmission grating 27 and is diffracted. The ±1st-order diffracted light in the x direction and y direction is deflected by the mirror 281 and passes through the aperture stop 29 to form four parallel beams with equal light intensity. The diffracted light of other orders is filtered by the aperture stop 29.

Specific embodiment five

The three-dimensional grating displacement measuring system capable of measuring vertical displacement in this embodiment has the same overall structure as that in Embodiment 1. Wherein, the cross-sectional view of the light splitting component 2 in the xoz direction is shown in FIG. 4 . This spectroscopic part is made up of collimating lens 21, two-dimensional transmission grating 27, lens 282, aperture stop 29, and the grating period of described two-dimensional transmission grating 27x direction and y direction is equal, the laser light emitted by single-frequency laser source 1 passes collimator After being collimated by the straight lens 21, it enters the two-dimensional transmission grating 27 and is diffracted. The ±1st-order diffracted light in the x direction and y direction is deflected by the lens 282 and passes through the aperture stop 29 to form four beams of parallel outgoing light with equal light intensity. The diffracted light of other orders is filtered by the aperture stop 29 .

Specific embodiment six

The three-dimensional grating displacement measuring system capable of measuring vertical displacement in this embodiment has the same overall structure as that in Embodiment 1. Wherein, the cross-sectional view of the light splitting component 2 in the xoz direction is shown in FIG. 5 . This spectroscopic part is made up of collimating lens 21, two-dimensional transmission grating 27, prism 282, aperture diaphragm 29, and the grating period of described two-dimensional transmission grating 27x direction and y direction is equal, and the laser light emitted by single-frequency laser source 1 passes collimator After being collimated by the straight lens 21, it enters the two-dimensional transmission grating 27 and is diffracted. The ±1st-order diffracted light in the x direction and y direction is deflected by the prism 282 and passes through the aperture stop 29 to form four beams of parallel outgoing light with equal light intensity. The diffracted light of other orders is filtered by the aperture stop 29 .

Specific embodiment seven

The three-dimensional grating displacement measuring system capable of measuring vertical displacement in this embodiment has the same overall structure as that in Embodiment 1. Wherein, the xoz direction sectional view of the refraction element 33 of the measuring arm is shown in FIG. 6 . The refraction element 33 of the measuring arm includes an aperture 331 and a refraction mirror 332, and the two beams of parallel measuring light whose propagation direction is parallel to the yoz plane pass through the aperture 331 and the refraction mirror 332, and the propagation direction is respectively deflected by ±θ _i and Diffraction occurs when it is incident on the two-dimensional reflective measuring grating 5, and the two beams of parallel measuring light whose propagation direction is parallel to the xoz plane pass through the diaphragm 331 and the refracting mirror 332, and the propagation direction is respectively deflected by ±θ _i and enters the two-dimensional The reflective measuring grating 5 diffracts.

Embodiment 8

The three-dimensional grating displacement measuring system capable of measuring vertical displacement in this embodiment has the same overall structure as that in Embodiment 1. Wherein, the xoz direction sectional view of the refraction element 33 of the measuring arm is shown in FIG. 7 . The measuring arm refraction element 33 includes an aperture 331 and a refraction prism 333. The two beams of parallel measuring light whose propagation direction is parallel to the yoz plane pass through the aperture 331 and the refraction prism 333, and the propagation direction is respectively deflected by ± _θi and incident on the Diffraction occurs on the two-dimensional reflective measurement grating 5, and the two beams of parallel measuring light whose propagation direction is parallel to the xoz plane pass through the diaphragm 331 and the refracting prism 333, and the propagation directions are respectively deflected by ± _θi and incident on the two-dimensional reflective measurement The grating 5 diffracts.

Specific embodiment nine

The three-dimensional grating displacement measuring system capable of measuring vertical displacement in this embodiment has the same overall structure as that in Embodiment 1. Wherein, the xoz direction sectional view of the refraction element 33 of the measuring arm is shown in FIG. 8 . The refraction element 33 of the measuring arm includes a diaphragm 331 and a first refraction lens 334, and the propagation directions of two parallel measuring lights whose propagation direction is parallel to the yoz plane are respectively deflected by ±θ after passing through the diaphragm 331 and the first refraction lens 334 _i and incident on the two-dimensional reflective measuring grating 5 to be diffracted, the two beams of parallel measuring light whose propagation direction is parallel to the xoz plane pass through the diaphragm 331 and the first refraction lens 334, and the propagation directions are respectively deflected by ± _θi and incident Diffraction into the two-dimensional reflective measuring grating 5 takes place.

Specific embodiment ten

The three-dimensional grating displacement measuring system capable of measuring vertical displacement in this embodiment has the same overall structure as that in Embodiment 1. Wherein, the xoz direction sectional view of the refraction element 33 of the measuring arm is shown in FIG. 9 . The refraction element 33 of the measuring arm includes a diaphragm 331 and a second refraction lens 334, and the propagation directions of the two parallel measuring lights whose propagation direction is parallel to the yoz plane pass through the diaphragm 331 and the second refraction lens 334 are respectively deflected by ±θ _i and incident on the two-dimensional reflective measuring grating 5 to undergo diffraction, the two beams of parallel measuring light whose propagation direction is parallel to the xoz plane pass through the diaphragm 331 and the second refraction lens 334, and the propagation direction is respectively deflected by ± _θi and incident Diffraction into the two-dimensional reflective measuring grating 5 takes place.

In the three-dimensional grating displacement measurement system that can measure vertical displacement in the above embodiments, the reference arm refraction element 35 is the structure of the measurement arm refraction element 33 described in Embodiment 7, Embodiment 8, Embodiment 9, and Embodiment 10. One of.

The present invention is not limited to the above-mentioned best implementation mode, and anyone should know that structural changes or method improvements made under the inspiration of the present invention, all technical solutions that are identical or similar to the present invention, all fall within the scope of protection of the present invention within.

Claims (4)

1. A three-dimensional grating displacement measurement system capable of measuring vertical displacement, characterized in that it comprises a single-frequency laser light source (1), a light splitting component (2), a polarization beam splitter prism (31), and a quarter-wave plate of a measuring arm (32), measuring arm refraction element (33), reference arm quarter-wave plate (34), reference arm refraction element (35), two-dimensional reflective reference grating (36), photoelectric detection and signal processing components (4 ) and two-dimensional reflective measuring grating (5); The two-dimensional reflective measurement grating (5) and the two-dimensional reflective reference grating (36) have the same surface appearance, and the x-direction period and the y-direction period of the two-dimensional reflective measurement grating (5) are both d; the two-dimensional reflective The x-direction period and the y-direction period of the formula reference grating (36) are both d; the x-direction refraction angle and the y-direction refraction angle of the described measuring arm refraction element (33) are _θi , and the reference arm refraction element (35) Both the x-direction refraction angle and the y-direction refraction angle are _θi , and satisfy _2dsinθi =±mλ, where λ is the wavelength of the single-frequency laser light source (1), and m is the diffraction order; The single-frequency laser light emitted by the single-frequency laser light source (1) is divided into four beams of parallel light with equal light intensity through the light splitting component (2), wherein the propagation direction of the two beams of light is parallel to the xoy plane, and the propagation direction of the other two beams of light is parallel to the xoy plane. The xoz plane is parallel, and these four beams of parallel light are divided into the measurement light deflected by 90 degrees in the propagation direction and the reference light propagating along the original direction after passing through the polarization beam splitter (31), and the polarization direction of the measurement light is perpendicular to the polarization direction of the reference light; After the four beams of parallel light beams of the measuring light pass through the quarter-wave plate (32) of the measuring arm whose fast axis direction is 45 degrees to the polarization direction of the measuring light, they are all deflected by the refracting element (33) of the measuring arm, and the deflected four beams The propagation directions of two beams of light in the beam of measurement light are parallel to the yoz plane, and the propagation directions of the other two beams of light are parallel to the xoz plane. They are respectively diffracted into +m-order diffracted measurement light and -m-order diffracted measurement light in the y direction, and the two beams of measurement light whose propagation direction is parallel to the xoz plane are incident on the two-dimensional reflective measurement grating (5) and are respectively diffracted into the x-direction The +m-order diffraction measurement light and the -m-order diffraction measurement light of the four beams of diffraction measurement light propagate along the opposite directions of the respective incident light propagation directions, and pass through the measurement arm refraction element (33), the measurement arm quarter-wave After the sheet (32) and the polarization beam splitter (31), it is incident on the photoelectric detection and signal processing unit (4); After the four beams of parallel light of the reference light pass through the reference arm quarter-wave plate (34) whose fast axis direction is 45 degrees to the polarization direction of the reference light, they are all deflected by the reference arm refraction element (35). The propagation direction of two beams of light in the beam of reference light is parallel to the xoy plane, the propagation direction of the other two beams of light is parallel to the xoz plane, and the two beams of reference light whose propagation direction is parallel to the xoy plane are incident on the two-dimensional reflective reference grating (36) and They are respectively diffracted into +m-order diffracted reference light and -m-order diffracted reference light in the y direction, and the two beams of reference light whose propagation direction is parallel to the xoz plane are incident on the two-dimensional reflective reference grating (36) and are respectively diffracted into the x-direction The +m-order diffraction reference light and the -m-order diffraction reference light, the four beams of diffraction reference light propagate along the opposite directions of the respective incident light propagation directions, and pass through the reference arm refraction element (35), the reference arm quarter-wave After the sheet (34) and the polarization beam splitter (31), it is incident on the photoelectric detection and signal processing unit (4); Two beams of diffracted measuring light in the x direction and two beams of diffracted reference beams in the x direction form two sets of interference on the surface of the photoelectric detection and signal processing component (4), and two beams of diffracted measuring light in the y direction and two beams of diffracted reference beams in the y direction Another two groups of interference are formed on the surface of the photoelectric detection and signal processing part (4); when other components are stationary and the two-dimensional reflective measurement grating (5) moves along the x-axis, y-axis and z-axis, the photoelectric detection and signal processing part (4) Output the linear displacements in x direction, y direction and z direction respectively. 2. A three-dimensional grating displacement measuring system capable of measuring vertical displacement according to claim 1, characterized in that: the single-frequency laser light source (1) is a semiconductor laser diode or a gas laser whose exit is terminated with an optical fiber. 3. A kind of three-dimensional grating displacement measuring system capable of measuring vertical displacement according to claim 1 or 2, characterized in that: the light splitting component (2) is one of the following four structures: First, the light-splitting component (2) is composed of a collimating lens (21), a first non-polarizing beam-splitting prism (22), a second non-polarizing beam-splitting prism (23), a first right-angle reflecting prism (24), a third non-polarizing beam-splitting prism Composed of a polarizing beam splitting prism (25) and a second right-angle reflecting prism (26), the laser light emitted by a single-frequency laser source (1) is collimated by a collimating lens (21) and then incident on a first non-polarizing beam splitting prism (22) to be divided into Two beams of light with equal light intensity and perpendicular propagation directions, one of which is incident on the second non-polarizing beam splitter prism (23) along the z direction and is divided into transmitted light with equal light intensity and reflected light and transmitted light with the propagation direction along the x direction The light is reflected by the first right-angle reflective prism (24) and travels along the x direction, and another beam of light travels along the x direction and enters the third non-polarizing beam splitter prism (25) to be divided into transmitted light with equal light intensity and a propagation direction along the -y direction The reflected light and the reflected light are reflected by the second right-angle reflective prism (26) and propagate along the x direction; Second, the light-splitting component is made up of a collimating lens (21), a two-dimensional transmission grating (27), a mirror (281), and an aperture stop (29). The grating period in the direction is equal, the laser light emitted by the single-frequency laser source (1) is collimated by the collimator lens (21), and then enters the two-dimensional transmission grating (27) and is diffracted. The ±1st-order diffracted light in the x direction and y direction Deflected by the reflector (281) and passed through the aperture stop (29) to form four beams of parallel outgoing light with equal light intensity, and the diffracted lights of other orders are filtered by the aperture stop (29); Third, the light splitting component is made up of a collimating lens (21), a two-dimensional transmission grating (27), a lens (282), and an aperture stop (29). The grating period is equal, the laser light emitted by the single-frequency laser light source (1) is collimated by the collimator lens (21), and then enters the two-dimensional transmission grating (27) and is diffracted. The ±1st order diffracted light in the x direction and y direction passes The lens (282) deflects and passes through the aperture stop (29) to form four bundles of parallel outgoing light with equal light intensity, and the diffracted lights of other orders are filtered by the aperture stop (29); Fourth, the light splitting component is made up of a collimating lens (21), a two-dimensional transmission grating (27), a prism (283), and an aperture stop (29). The grating period is equal, the laser light emitted by the single-frequency laser light source (1) is collimated by the collimator lens (21), and then enters the two-dimensional transmission grating (27) and is diffracted. The ±1st order diffracted light in the x direction and y direction passes The prism (283) deflects and passes through the aperture stop (29) to form four beams of parallel outgoing light with equal light intensity, and the diffracted lights of other orders are filtered by the aperture stop (29). 4. A kind of three-dimensional grating displacement measuring system capable of measuring vertical displacement according to claim 1 or 2, characterized in that: the refraction element (33) of the measuring arm is one of the following four structures: First, the refraction element (33) of the measuring arm includes an aperture (331) and a refraction mirror (332), and the two beams of parallel measuring light whose propagation direction is parallel to the yoz plane pass through the aperture (331) and the refraction mirror (332) After the propagation direction is respectively deflected by ± _θi and incident to the two-dimensional reflective measurement grating (5) for diffraction, the two beams of parallel measurement light whose propagation direction is parallel to the xoz plane pass through the diaphragm (331) and the refraction The propagation direction after the reflector (332) is respectively deflected ± θ _i and incident to the two-dimensional reflective measurement grating (5) for diffraction; Second, the refraction element (33) of the measuring arm includes a diaphragm (331) and a refraction prism (333), and the two beams of parallel measuring light whose propagation direction is parallel to the yoz plane pass through the diaphragm (331) and the refraction prism (333) ) after the propagation directions are respectively deflected ± θ _i and incident to the two-dimensional reflective measurement grating (5) for diffraction, the two beams of parallel measurement light whose propagation direction is parallel to the xoz plane pass through the diaphragm (331) and the refracting prism ( 333) The rear propagation direction is respectively deflected by ±θ _i and incident to the two-dimensional reflective measurement grating (5) for diffraction; Third, the measuring arm refraction element (33) includes an aperture (331) and a first refraction lens (334), and the two beams of parallel measuring light whose propagation direction is parallel to the yoz plane pass through the aperture (331) and the first refraction lens (334). After the refraction lens (334), the propagation direction is respectively deflected by ±θ _i and incident to the two-dimensional reflective measurement grating (5) for diffraction, and the two beams of parallel measurement light whose propagation direction is parallel to the xoz plane pass through the diaphragm (331) After the first refracting lens (334) and the propagation direction are respectively deflected ± θ _i and incident to the two-dimensional reflective measurement grating (5) to diffract; Fourth, the measuring arm refraction element (33) includes an aperture (331) and a second refraction lens (334), and the two beams of parallel measuring light whose propagation direction is parallel to the yoz plane pass through the aperture (331) and the second refraction lens (334). After the refraction lens (334), the propagation direction is respectively deflected by ±θ _i and incident to the two-dimensional reflective measurement grating (5) for diffraction, and the two beams of parallel measurement light whose propagation direction is parallel to the xoz plane pass through the diaphragm (331) and the second refraction lens (334), the propagating direction is respectively deflected by ± _θi and incident to the two-dimensional reflective measurement grating (5) to undergo diffraction.