High-precision air-floating linear table used in inclined mode

Abstract

The invention discloses a high-precision air-floating linear table used in an inclined manner, which is used in an optical synthetic aperture imaging system with a variable base line so as to drive a structural member of a sub-aperture and a combined light imaging light beam to perform inclined high-precision variable base line motion. Comprising two sets of inclined air-floating linear tables, and each set of inclined air-floating linear table comprises an inclined granite base, a granite air-floating guide rail, a set of linear motor, a set of grating ruler, two air-floating sleeves and synchronous belts, synchronous wheels and counterweights thereof, and two sub-apertures and supports and counterweights thereof. The inclined granite bases are triangles with the angle of 30 degrees, the bottom faces of the inclined granite bases are installed on the main base, the two inclined granite bases are arranged in a staggered mode, the air flotation linear guide rails are installed on the inclined faces, and the included angle of the two air flotation linear guide rails is 60 degrees. The device is small in occupied space, simple in structure and mature in used parts, and has the advantages of being easy to implement, high in universality, high in generalization performance, high in cost performance and high in precision.

Description

Technical Field

[0001] The invention relates to the technical field of astronomical observation, and in particular to a high-precision air-floating linear stage for tilting. Background Art

[0002] Optical synthetic aperture technology is a technology that precisely arranges multiple optical elements or optical systems of smaller apertures so that the light beams passing through each sub-aperture can achieve coherent superposition of the light field on the focal plane, and after image restoration processing, achieves a diffraction-limited resolution equivalent to that of a single large-aperture system. Depending on whether the combined light path in the optical synthetic aperture imaging system is constrained, it can be distinguished into Fizeau type, Michelson type, and Hyper telescope type. The Fizeau type interference imaging system has the advantages of instantaneous imaging, high imaging efficiency, and a large field of view, but the technical requirements for implementation are also higher. The polygon formed by the sub-aperture entrance pupil of the Fizeau type interference imaging system and the polygon formed by the exit pupil of the imaging system have strict similarity, and the similarity ratio is the magnification of the sub-aperture. This has very high position and angle accuracy requirements for the sub-aperture and the combined light imaging beam it generates when the baseline moves. Therefore, the present invention proposes a high-precision air-floating linear stage for tilting to meet the above requirements.

[0003] Existing methods and means: 1. The wide-field imaging interferometry (WIIT) device established by NASA contains only two sub-apertures with a diameter of 25 mm, which can be placed horizontally at both ends of the same linear air-floating linear stage. The baseline range of the device is from 25 mm to 250 mm, which is different from the use of the inclined air-floating linear stage in this scheme.

[0004] 2. The National Astronomical Observatory of the Chinese Academy of Sciences designed and built a Fizeau imaging interferometer test device (FIIT), which contains three 100mm sub-apertures with a Golay-3 distribution (equilateral triangle). The baseline is fixed and cannot be adjusted, so there is no need for a translation stage to drive the sub-aperture and the combined imaging beam to move.

[0005] 3. The Very Large Telescope (VLT) built by the European Southern Observatory in Chile consists of four primary mirrors with a diameter of 8.2m and four movable auxiliary mirrors with an aperture of 1.8m. These telescopes can work alone or in groups of two or three to form a huge interferometer array. The light beams from different telescopes are combined through underground tunnels. The baseline can reach 200m and the angular resolution is 0.001″. The four small-aperture telescopes with an aperture of 1.8m move on horizontal rails, which is different from the use of the inclined air-floating linear stage in this scheme.

[0006] Disadvantages of existing technology: (1) Currently, the variable baseline motion stages in existing optical synthetic aperture imaging systems at home and abroad are mostly mechanical guides with low precision.

[0007] (2) Currently, the variable baseline motion stages in existing optical synthetic aperture imaging systems at home and abroad are mostly horizontally arranged, which cannot achieve spatial variable baseline motion and does not require additional force and torque balancing devices.

[0008] The present invention relates to a Fizeau-type variable baseline optical synthetic aperture interference imaging system, the main optical axis of which is arranged horizontally, and the system includes 4 sub-apertures, and correspondingly has 4 combined imaging beams, the centers of the entrance pupils of the 4 sub-apertures are located at the 4 vertices of the same rectangle, and the optical axis projections of the 4 combined imaging beams are also at the 4 vertices of a rectangle. When the imaging system changes its baseline, the 4 sub-apertures expand outward or contract inward equidistantly along the diagonal of the rectangle, and the 4 combined imaging beams also perform the above operations accordingly. The above two rectangles need to always maintain strict similarity when the system changes its baseline, and the similarity ratio is the angular magnification of the sub-aperture, which is 5 in this example. In view of the above situation and requirements, the Fizeau-type optical synthetic aperture interference imaging system in this example requires 4 sets of high-precision air-floating linear stages used for tilting to drive the sub-apertures and the structural parts of the combined imaging beams to perform variable baseline movement, so as to ensure that the above two rectangles always maintain strict similarity when the system changes its baseline.

[0009] The information disclosed in this background technology section is only intended to deepen the understanding of the overall background technology of the present invention, and should not be regarded as acknowledging or suggesting in any form that the information constitutes the prior art already known to those skilled in the art. Summary of the invention

[0010] In view of the problems existing in the prior art, the purpose of the present invention is to provide a high-precision air-floating linear stage for tilting, which is used to drive the structural parts of the sub-aperture and the combined-light imaging beam in the optical synthetic aperture imaging system to perform tilted high-precision variable baseline movement, thereby ensuring that the sub-aperture and the combined-light imaging beam reach the theoretical position and posture with smaller straightness error and angle error.

[0011] In order to achieve the above object, the present invention adopts the following technical solutions: A high-precision air-floating linear stage for tilting, which is used in an optical synthetic aperture imaging system with a variable baseline to drive the structural parts of the sub-aperture and the combined imaging beam to perform tilted high-precision variable baseline movement; comprising: Tilted granite base a, tilted granite base b, granite air-floating linear guide a, granite air-floating linear guide b, linear motor a, linear motor b, grating ruler a, grating ruler b, air-floating sleeve a, air-floating sleeve b, air-floating sleeve c, air-floating sleeve d, sub-aperture a, sub-aperture b, sub-aperture c, sub-aperture d, sub-aperture a support, sub-aperture b support, sub-aperture c support, sub-aperture d support, sub-aperture a counterweight, sub-aperture b counterweight, sub-aperture c counterweight, sub-aperture d counterweight, air-floating sleeve a synchronous belt, air-floating sleeve b synchronous belt, air-floating sleeve c synchronous belt, air-floating sleeve d synchronous belt, air-floating sleeve a synchronous wheel, air-floating sleeve b synchronous wheel, air-floating sleeve c synchronous wheel, air-floating sleeve d synchronous wheel, air-floating sleeve a counterweight, air-floating sleeve b counterweight, air-floating sleeve c counterweight and air-floating sleeve d counterweight; wherein, The cross-section of the inclined granite base a and the inclined granite base b is a triangle with an angle of 30°. The bottom surfaces of the two are installed on the total base. The two inclined granite bases are arranged alternately, and the granite air-floating linear guide a and the granite air-floating linear guide b are installed on the inclined surfaces respectively. The angle between the two air-floating linear guides is 60°. Two air-floating sleeves are installed on each air-floating linear guide rail, a vertically placed sub-aperture support is installed on each air-floating sleeve, and one sub-aperture is installed on each sub-aperture support. The entrance pupils of the four sub-apertures are on the same plane, with the same posture, and the centers of the entrance pupils are at the four vertices of the rectangle. A set of linear motors is installed on each air-floating linear guide rail to drive the two sub-apertures to perform variable baseline movement, and a set of grating rulers is installed to feedback the positions of the two sub-apertures; A counterweight is installed on each sub-aperture support to balance the torque generated at the centroid of the air-floating sleeve due to the eccentricity of the sub-aperture, so as to ensure the high-precision and smooth movement of the air-floating sleeve; A synchronous belt, a synchronous wheel and a counterweight are installed on each air flotation sleeve. The synchronous wheel is fixed to the upper end of the air flotation guide rail. One end of the synchronous belt is fixed to the air flotation sleeve, and the other end bypasses the synchronous wheel and is connected to the counterweight, which is used to balance the gravity components of the air flotation sleeve, the sub-aperture and its support and the counterweight, as well as the torque generated at the centroid of the air flotation sleeve due to the eccentricity of the above-mentioned structure. The counterweight of the air flotation sleeve moves vertically up and down with the movement of the air flotation sleeve.

[0012] Furthermore, the air flotation sleeve counterweight and the sub-aperture counterweight are both made of lead material.

[0013] By adopting the above technical solution, the present invention has the following beneficial effects: 1) The technology involved is relatively mature and easy to implement. At present, the manufacturing and application technologies of air-floating linear stages, grating scales, linear motors, synchronous belts, synchronous wheels, etc. are relatively mature, and the feasibility and reliability of this invention are relatively high; 2) Strong versatility. The invention is generally applicable to variable baseline spatially distributed synthetic aperture imaging systems; 3) Strong promotional potential. The invention can be promoted in systems with high-precision tilt motion requirements; 4) High cost performance. The invention can achieve its functions and performance by using mature parts, fewer motion mechanisms and devices, smaller space, lower cost and difficulty; 5) High precision. The tilting air-floating linear stage with a follow-up force and torque balance device can achieve micron-level and micro-radian-level linearity and angular error motion on a meter-level stroke. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] In order to more clearly illustrate the specific implementation methods of the present invention or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0015] Figure 1 This is a schematic diagram of the composition structure of the high-precision air-floating linear stage used for tilting in the present invention.

[0016] Figure 2 This is a partial enlarged view of a sub-aperture variable baseline air-floating linear stage of the present invention.

[0017] Figure 3 This is a side view of the sub-aperture variable baseline air-floating linear stage of the present invention.

[0018] Figure 4 This is the force diagram of the air-floating sleeve of the sub-aperture inclined air-floating linear stage of the present invention.

[0019] Figure 5 Schematic diagram of the position relationship between the entrance pupil and the exit pupil of the present invention. DETAILED DESCRIPTION

[0020] The technical solution of the present invention will be described clearly and completely below in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0021] The specific implementation of the present invention is described in detail below in conjunction with the accompanying drawings. It should be understood that the specific implementation described here is only used to illustrate and explain the present invention, and is not used to limit the present invention.

[0022] Combination Figure 1-3As shown, the present invention proposes a high-precision air-floating linear stage for tilting, taking a sub-aperture variable baseline air-floating linear stage as an example, the high-precision air-floating linear stage is used in a variable baseline optical synthetic aperture imaging system to drive the structural parts of the sub-aperture and the combined light imaging beam to perform tilted high-precision variable baseline motion; comprising: Tilted granite base a1, tilted granite base b2, granite air-floating linear guide a3, granite air-floating linear guide b4, linear motor a5, linear motor b6, grating ruler a7, grating ruler b8, air-floating sleeve a9, air-floating sleeve b10, air-floating sleeve c11, air-floating sleeve d12, sub-aperture a13, sub-aperture b14, sub-aperture c15, sub-aperture d16, sub-aperture a support 17, sub-aperture b support 18, sub-aperture c support 19, sub-aperture d support 20, sub-aperture a counterweight 21, sub-aperture b counterweight 22, sub-aperture c counterweight 23, sub-aperture d counterweight 24, air-floating sleeve a synchronous belt 25, air-floating sleeve b synchronous belt 26, air-floating sleeve c synchronous belt 27, air-floating sleeve d synchronous belt 28, air-floating sleeve a synchronous wheel 29, air-floating sleeve b synchronous wheel 30, air-floating sleeve c synchronous wheel 31, air-floating sleeve d synchronous wheel 32, air-floating sleeve a counterweight 33, air-floating sleeve b counterweight 34, air-floating sleeve c counterweight 35 and air-floating sleeve d counterweight 36; wherein, The cross-section of the inclined granite base a1 and the inclined granite base b2 is a triangle with an angle of 30°. The bottom surfaces of the two are installed on the total base. The two inclined granite bases are arranged alternately. The granite air-floating linear guide a3 and the granite air-floating linear guide b4 are installed on the inclined surfaces respectively. The angle between the two air-floating linear guides is 60°. Two air-floating sleeves are installed on each air-floating linear guide rail, a vertically placed sub-aperture support is installed on each air-floating sleeve, and a sub-aperture is installed on each sub-aperture support. The entrance pupils of the four sub-apertures are on the same plane, with the same posture, and the center of the entrance pupil is at the four vertices of the rectangle; the specific structure is as follows: Figure 5 As shown, the figure shows the entrance pupil 37, the sub-aperture baseline 38, the combined imaging beam baseline 39 and the exit pupil 40.

[0023] A set of linear motors is installed on each air-floating linear guide rail to drive the two sub-apertures to perform variable baseline movement, and a set of grating rulers is installed to feedback the positions of the two sub-apertures; A counterweight is installed on each sub-aperture support to balance the torque generated at the centroid of the air-floating sleeve due to the eccentricity of the sub-aperture, so as to ensure the high-precision and smooth movement of the air-floating sleeve; A synchronous belt, a synchronous wheel and a counterweight are installed on each air flotation sleeve. The synchronous wheel is fixed to the upper end of the air flotation guide rail. One end of the synchronous belt is fixed to the air flotation sleeve, and the other end bypasses the synchronous wheel and is connected to the counterweight, which is used to balance the gravity components of the air flotation sleeve, the sub-aperture and its support and the counterweight, as well as the torque generated at the centroid of the air flotation sleeve due to the eccentricity of the above-mentioned structure. The counterweight of the air flotation sleeve moves vertically up and down with the movement of the air flotation sleeve.

[0024] Both the air flotation sleeve counterweight and the sub-aperture counterweight are made of lead material, which has the advantages of high density and small size. Threaded holes cannot be processed and can only be lifted up from the bottom by a tray.

[0025] In order to more clearly demonstrate the working principle of this application, Figure 1 Also shown are the collimator 37, the sub-aperture incident light 38, the sub-aperture outgoing light 39, etc., which are not part of the tilted air-floating linear stage.

[0026] The above-mentioned sub-aperture variable baseline air-floating linear stage of the present application mainly includes 2 sets of inclined air-floating linear stages, and each set of inclined air-floating linear stages includes a basically identical structure, including 1 inclined granite base, 1 granite air-floating guide rail, a set of linear motors, a set of grating scales, 2 air-floating sleeves and their synchronous belts, synchronous wheels and counterweights, 2 sub-apertures and their supports and counterweights. The inclined granite base is a triangle with an angle of 30°, and the bottom surface is installed on the main base. The two inclined granite bases are staggered, and the air-floating linear guide rails are installed on the inclined surface. The angle between the two air-floating linear guide rails is 60°.

[0027] The working principle of the present invention is as follows: Continuing with the example of the sub-aperture variable baseline air-floating linear stage, the working principle of the Heguang urban and rural variable baseline air-floating linear stage is consistent with it. Two sets of linear motors drive four air-floating sleeves to perform linear motion along two tilted air-floating guide rails. The grating scale provides real-time feedback on the position of the air-floating sleeves, and the four sub-apertures are supported and mounted on the four air-floating sleeves. When the sub-apertures are at different baselines (920mm-310mm), the entrance pupils of the four sub-apertures are always on the same plane, and the postures remain consistent. At the same time, the centers of the entrance pupils of the four sub-apertures are at the four vertices of the rectangle. The tilted air-floating linear stage of the Heguang imaging beam is similar to the tilted air-floating linear stage of the sub-aperture, the difference being that the stroke is 1 / 5 of that of the tilted air-floating linear stage of the sub-aperture (the magnification of the sub-aperture).

[0028] Sub-aperture counterweight design of the present invention: Since the entrance pupils of the four sub-apertures are on the same plane, and the tilted air-floating linear stage needs to be installed offset in the direction of light propagation, the center of gravity of the sub-aperture is not on the center line of the air-floating sleeve. When the gravity of the sub-aperture acts on the air-floating sleeve, it will cause the air-floating sleeve to roll (rotate along the direction of movement of the air-floating sleeve), which will introduce a roll angle error and affect the attitude accuracy of the sub-aperture and the imaging accuracy of the system. This requires the design of a counterweight on the sub-aperture support to balance the torque generated at the centroid of the air-floating sleeve due to the eccentricity of the sub-aperture, so as to ensure the high-precision and smooth movement of the air-floating sleeve; Solidworks software was used to build a 3D model of the subaperture variable baseline air-floating linear stage. Considering the stability of the air-floating linear stage, the subaperture counterweight was installed as close to the air-floating sleeve as possible. Further considering factors such as the spatial size of the imaging system, the size and installation position of the subaperture counterweight were designed, and lead was selected as the material of the subaperture counterweight. The final design criteria are: the center of gravity of all loads above the air-floating sleeve, including the subaperture and its support and the subaperture counterweight, is located on the center line of the air-floating sleeve and the air-floating guide rail, eliminating the rolling tendency of the air-floating sleeve.

[0029] The present invention's air flotation sleeve counterweight design: Considering the fact that the air-floating guide rail of the inclined air-floating linear stage is installed at an angle of 30° to the horizontal plane, there is basically no friction between the air-floating sleeve and the air-floating guide rail, the air-floating sleeve and the load on it are heavy, and the linear motor thrust is insufficient, it is necessary to design a counterweight mechanism for the air-floating sleeve to balance the component of the gravity of the air-floating sleeve and the load on it along the direction of movement of the air-floating sleeve and the torque generated at the centroid of the air-floating sleeve due to the eccentricity of the above load. The counterweight of the air-floating sleeve is fixed by a synchronous belt and a synchronous wheel and moves vertically up and down with the movement of the air-floating sleeve to ensure that the air-floating sleeve can move smoothly and with high precision when the output of the linear motor is small and that the air-floating sleeve and the sub-aperture can remain stationary when the system is imaged (the motor does not exert force). In order to balance the gravity component and torque of the air-floating sleeve and the load on it, it is necessary to determine the mass of the counterweight of the air-floating sleeve and the connection position of the synchronous belt on the air-floating sleeve. The method for determining the mass of the counterweight of the air-floating sleeve and the connection position of the synchronous belt on the air-floating sleeve is as follows: Combination Figure 4 As shown, ignoring the friction of the synchronous wheel, the pulling force of the synchronous belt on the air-floating sleeve is equal to the gravity of the mass of the air-floating sleeve counterweight, which is also equal to the component of the total gravity of the air-floating platform and its load along the moving direction of the air-floating sleeve, then: F 拉 =sin30°×(M 套 +M 载荷 ) × g; In the formula, F 拉 is the tension of the synchronous belt, M 套 is the mass of the air flotation sleeve, M 载荷 is the total mass of the subaperture, subaperture support, subaperture counterweight and other loads.

[0030] The torque generated by the tension provided by the synchronous belt is equal to the pitch torque generated by the gravity of the air bearing table and its load, so: H=2× F 压 ×L / (M 套 ×g+F 压 )-H 套 ; Where H is the vertical height from the connection point between the synchronous belt and the air flotation sleeve to the upper surface of the air flotation sleeve, F 压 is the total gravity of the air-floating platform and its load, L is F 压 The vertical distance to the centroid of the air flotation sleeve, H 套 It is the distance from the centroid of the air flotation sleeve to its upper surface.

[0031] According to the above two formulas, the mass of the air-floating sleeve counterweight and the connection position of the synchronous belt on the air-floating sleeve can be determined.

[0032] The working process of the present invention is as follows: Continuing with the example of the sub-aperture variable-baseline air-floating linear stage, the working process of the Heguang urban and rural variable-baseline air-floating linear stage is the same.

[0033] 1) When the imaging system changes the baseline, the four air-floating sleeves drive the four sub-apertures, sub-aperture supports and sub-aperture counterweights to move along the air-floating guide rails. The grating ruler provides real-time feedback to ensure that the centers of the four sub-aperture entrance pupils are located at the four vertices of the same rectangle. 2) The air-floating sleeve counterweight is fixed by a synchronous belt and a synchronous wheel and moves vertically up and down with the movement of the air-floating sleeve, ensuring the air-floating sleeve's low straightness and angle error movement, and ensuring the position and attitude accuracy of the four sub-apertures; 3) After the imaging system completes baseline change, the linear motor is enabled and the imaging system performs combined light imaging; 4) Repeat steps 1)-3) to change the imaging system baseline multiple times; 5) Synthesize images collected under multiple baselines.

[0034] Compared with the prior art, the innovations and technical effects of this application mainly include: 1) The tilted air-floating linear stage of the present invention is applied to an optical synthetic aperture imaging system with a variable baseline composed of four sub-apertures and four light-combining imaging structures, and the spatial variation of the four sub-aperture baselines and the four light-combining imaging baselines can be achieved through staggered arrangement; 2) The inclined air-floating linear stage of the present invention, when combined with a follow-up force and torque balancing device, can achieve micrometer-level and micro-radian-level linearity and angular error motion over a meter-level stroke; 3) The tilting air-floating linear stage of the present invention can realize the tilting movement of parts while saving the number of motion mechanisms, cost and space; 4) The follow-up force and torque balancing device of the inclined air-floating linear stage involved in the present invention occupies less space, has a simple structure, and uses mature components. It does not require an active motion mechanism and a complex control system to meet the functional and performance requirements of the inclined air-floating linear stage, saving space, cost and difficulty.

[0035] In addition, the present application can also expand the following aspects: the optical axis of the optical synthetic aperture imaging system is not limited to the horizontal, it can be in any direction; different numbers and distribution forms of sub-apertures; different angular magnifications of sub-apertures; the stroke of the tilted air-floating linear stage can be arbitrary; the installation angle of the tilted air-floating linear stage can be arbitrary; the tilted air-floating linear stage can be applied to any system with tilting motion requirements; the counterweight can be made of any material.

[0036] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A high-precision air-floating linear stage for tilting, wherein the high-precision air-floating linear stage is used in a variable-baseline optical synthetic aperture imaging system to drive the sub-aperture and the structure of the combined imaging beam to perform tilted high-precision variable-baseline movement; characterized in that: include: Inclined granite base a (1), inclined granite base b (2), granite air-floating linear guide a (3), granite air-floating linear guide b (4), linear motor a (5), linear motor b (6), grating scale a (7), grating scale b (8), air-floating sleeve a (9), air-floating sleeve b (10), air-floating sleeve c (11), air-floating sleeve d (12), sub-aperture a (13), sub-aperture b (14), sub-aperture c (15), sub-aperture d (16), sub-aperture a support (17), sub-aperture b support (18), sub-aperture c support (19), sub-aperture d support (20), sub-aperture a counterweight (21), sub-aperture b counterweight (22), sub-aperture c counterweight (23), sub-aperture d counterweight (24), air-floating sleeve a synchronous belt (25), air-floating sleeve b synchronous belt (26), air-floating sleeve c synchronous belt (27), air-floating sleeve d synchronous belt (28), air-floating sleeve a synchronous wheel (29), air-floating sleeve b synchronous wheel (30), air-floating sleeve c synchronous wheel (31), air-floating sleeve d synchronous wheel (32), air-floating sleeve a counterweight (33), air-floating sleeve b counterweight (34), air-floating sleeve c counterweight (35), and air-floating sleeve d counterweight (36); wherein, The cross-section of the inclined granite base a (1) and the inclined granite base b (2) is a triangle with an angle of 30°. The bottom surfaces of the two are mounted on the main base. The two inclined granite bases are arranged alternately. The granite air-floating linear guide rail a (3) and the granite air-floating linear guide rail b (4) are respectively mounted on the inclined surfaces. The included angle of the two air-floating linear guide rails is 60°. Two air-floating sleeves are installed on each air-floating linear guide rail, a vertically placed sub-aperture support is installed on each air-floating sleeve, and one sub-aperture is installed on each sub-aperture support. The entrance pupils of the four sub-apertures are on the same plane, with the same posture, and the centers of the entrance pupils are at the four vertices of the rectangle. A set of linear motors is installed on each air-floating linear guide rail to drive the two sub-apertures to perform variable baseline movement, and a set of grating rulers is installed to feedback the positions of the two sub-apertures; A counterweight is installed on each sub-aperture support to balance the torque generated at the centroid of the air-floating sleeve due to the eccentricity of the sub-aperture, so as to ensure the high-precision and smooth movement of the air-floating sleeve; A synchronous belt, a synchronous wheel and a counterweight are installed on each air flotation sleeve. The synchronous wheel is fixed to the upper end of the air flotation guide rail. One end of the synchronous belt is fixed to the air flotation sleeve, and the other end bypasses the synchronous wheel and is connected to the counterweight, which is used to balance the gravity components of the air flotation sleeve, the sub-aperture and its support and the counterweight, as well as the torque generated at the centroid of the air flotation sleeve due to the eccentricity of the above-mentioned structure. The counterweight of the air flotation sleeve moves vertically up and down with the movement of the air flotation sleeve.

2. The high-precision air-floating linear stage for tilting according to claim 1, characterized in that: The air flotation sleeve weight and the sub-aperture weight are both made of lead material.

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