An optical non-contact high steepness profile measuring device

Abstract

The present application relates to a kind of optical non-contact high steep profile measurement device, belong to the field of precision measurement.The device is mainly by precision motion execution module, profile surface detection module, precision displacement measurement module is constituted.The present application uses the spectral dispersion confocal displacement measuring head with certain installation inclination to realize the detection of high steep profile, utilizes two-dimensional orthogonal linear motion platform to carry the head and moves according to specified trajectory, is combined with the rotation of the measured part on precision rotary shaft to realize three-dimensional profile scanning.The device uses the displacement of the head by multi-axis double-frequency laser interferometric distance measurement of optical fiber light guide and reference datum frame technology to carry out high-precision measurement and realize Abbe error compensation.The present application measurement device structure simplifies, and can realize the ultra-precision measurement of high steep precision parts.

Description

Technical Field

[0001] This invention belongs to the field of precision measurement, specifically relating to an optical non-contact high-steep profile measurement device. Background Technology

[0002] With the widespread development of precision engineering, the demand for precision parts is constantly increasing. The geometric profile accuracy of a part is often a core technical indicator that determines its quality and performance. The key to obtaining a high-quality profile lies in providing reliable and effective precision measurements to guide manufacturing and conduct quality evaluation. This places higher demands on precision profile measurement technology and equipment.

[0003] Currently, commercial contour detection devices can be classified into the following categories according to their implementation methods: contact contour scanning method, coordinate measuring machine method, and non-contact optical scanning method.

[0004] The contact profile scanning method utilizes a mechanical probe and a measurement reference datum to scan the profile of an object along a one-dimensional direction. During measurement, the probe remains in contact with the surface being measured; when scanning along a straight line, changes in the profile height cause displacement of the mechanical probe, which can be accurately measured by a sensor. The profile value can then be calculated by combining this displacement with the geometric relationship of the probe structure. This method is simple in structure and easy to implement, but it has drawbacks such as limited measurement dimensions, complex adjustment, limited sagittal height of the measurable profile, and the risk of surface damage.

[0005] Coordinate measuring machine (CMM) uses a mechanical or optical probe to contact the surface of the workpiece. Three mutually perpendicular linear motion axes, each equipped with an optical scale, move and record the spatial position of the probe to obtain the coordinates of the measurement points and thus acquire the contour value. While CMMs offer strong versatility and automation, they generally employ a point-by-point measurement mode, resulting in low measurement efficiency and sampling density. The use of optical scales for displacement measurement limits accuracy and does not meet Abbe's principle. Panasonic of Japan improved upon traditional CMMs to enhance measurement accuracy by employing a reference frame combined with laser interferometry to improve three-dimensional displacement measurement accuracy. The displacement measurement optical path is designed at the same height as the probe contact point to reduce Abbe error, achieving contour measurement accuracy within a few hundred nanometers. However, due to limitations in the probe system structure, probe replacement is required when measuring steep contours, resulting in some accuracy loss. Furthermore, the Abbe error-eliminating measurement optical path somewhat limits the size of the workpiece and the measurable height. The three-dimensional orthogonal measurement method also leads to low instrument efficiency and a large size.

[0006] A typical example of non-contact optical scanning is the Luphos series profilometer from Taylor Instruments, Inc. This instrument employs a four-axis structure, using two linear motion axes and one rotary axis to achieve a non-contact optical multi-wavelength interferometric probe that comprehensively scans the surface of the workpiece. Simultaneously, the additional probe rotation axis ensures that the probe always measures along the contour normal of the workpiece, reducing the requirements for the probe's working angle and focal point size. This method offers advantages such as compact structure, adherence to Abbe's principle, high measurement accuracy, and high efficiency; however, the additional rotary axis increases the instrument's structural complexity and implementation difficulty. Summary of the Invention

[0007] The technical problem to be solved by the present invention is to provide a simple, high-precision, and steep contour detection device to meet the high-precision contour detection requirements in the manufacturing of precision parts.

[0008] The technical solution adopted by the present invention to solve the above-mentioned technical problems is: an optical non-contact high-steepness contour measurement device, comprising: a precision air-bearing rotary table 1, a horizontal linear motion stage 2, a vertical linear motion stage 3, a spectral dispersive confocal displacement probe 4, a laser 5, an optical fiber 6, a beam expander 7, a first beam splitter 8, a second beam splitter 9, a third beam splitter 10, a second conversion mirror 11, a first conversion mirror 12, a third interferometer 13, a second interferometer 14, a first interferometer 15, a first beam coupler 16, a second beam coupler 17, a third beam coupler 18, a fourth beam coupler 19, a first receiver 20, a second receiver 21, a third receiver 22, a fourth receiver 23, an X-axis displacement measurement reference 24, a Z-axis displacement measurement reference 25, a mechanical platform 26, and a controller 27, wherein...

[0009] The precision air-bearing rotary table 1 is used to fix the part to be measured 28 and perform precision rotary motion to realize the surface contour scanning of the part to be measured. Its rotation axis is defined as the Z-axis of the measuring device.

[0010] The horizontal linear motion stage 2 is used to perform the horizontal movement and positioning of the spectral dispersive confocal displacement probe 4, so that it can scan the contour of the measured part 28 radially, and its movement direction is orthogonal to the Z-axis.

[0011] The vertical linear motion stage 3 is installed on the horizontal linear motion stage 2 and is used to carry the spectral dispersive confocal displacement probe 4 to move and position in the vertical direction. Its direction of movement is parallel to the Z-axis.

[0012] The controller 27 drives the horizontal linear motion stage 2 and the vertical linear motion stage 3 to work together, and controls the spectral dispersive confocal displacement probe 4 to scan and measure along a specified trajectory, so that the contour of the measured part 28 is always within the effective stroke range of the spectral dispersive confocal displacement probe 4 during scanning.

[0013] The spectral dispersive confocal displacement probe 4 is mounted on the vertical linear motion stage 3 and is used for non-contact detection of the surface contour information of the measured part 28.

[0014] Laser 5 is used to provide a frequency-stabilized dual-frequency helium-neon laser for interferometric measurement of the two-dimensional spatial position of the spectral dispersive confocal displacement probe 4. The laser emitted from laser 5 is transmitted to the vertical linear motion stage 3 in the device by optical fiber 6.

[0015] Beam expander 7 expands the laser beam transmitted from fiber 6, and the expanded laser beam can be used to build an interferometric ranging optical path;

[0016] The first beam splitter 8 is used to separate the laser into a reference beam and a measurement beam. The reference beam is used to suppress environmental errors and interference in interferometric measurements, and the measurement beam is used to measure the displacement of the Z-axis 1 path and the X-axis 2 path.

[0017] The second beam splitter 9 is used to split the laser into two beams, one for Z-axis interferometric ranging and the other for X-axis interferometric ranging.

[0018] The third beam splitter 10 is used to split the X-axis measurement beam into two beams, of which the 90° folded portion of the beam is the X-axis measurement beam 1.

[0019] The second deflector 11 is used to deflect the laser beam transmitted through the third beam splitter 10 by 90° to form the X-axis measurement beam 2;

[0020] The first turning mirror 12 is used to turn the laser beam reflected by the second beam splitter 9 by 90°, and the direction of the beam after turning is parallel to the Z-axis of the device.

[0021] The third interferometer 13 is used to realize the interferometric measurement of the X-axis measurement beam 2;

[0022] The second interferometer 14 is used to realize the interferometric measurement of the X-axis measurement beam 1;

[0023] The first interferometer 15 is used to realize the interferometric measurement of Z-axis displacement;

[0024] The first beam coupler 16, the second beam coupler 17, the third beam coupler 18, and the fourth beam coupler 19 are used to receive, couple, and transmit the optical signals from the third interferometer 13, the second interferometer 14, the first interferometer 15, and the first beam splitter 8 to the first receiver 20, the second receiver 21, the third receiver 22, and the fourth receiver 23, so as to realize the photoelectric conversion of the reference signal and the measurement signal.

[0025] The X-axis displacement measurement reference 24 is fixed on a stable mechanical platform 26. Its plane normal is defined as the X-axis of the measuring device. As a component of the dual-frequency laser interferometric ranging optical path, it realizes the measurement of the X-axis dual-optical-path displacement.

[0026] Z-axis displacement measurement reference 25 is fixed on a stable mechanical platform 26, and its plane normal is parallel to the Z-axis. As a component of the dual-frequency laser interferometric ranging optical path, it realizes the measurement of displacement in the Z direction.

[0027] The controller 27 is used to realize the programmed motion of the precision air-bearing rotary table 1, the horizontal linear motion table 2, and the vertical linear motion table 3, as well as the real-time acquisition, processing, and analysis and evaluation of the output signals of the precision air-bearing rotary table 1, the horizontal linear motion table 2, the vertical linear motion table 3, the first receiver 20, the second receiver 21, the third receiver 22, and the fourth receiver 23.

[0028] Furthermore, the laser emitted from laser 5 is transmitted into the measurement optical path via optical fiber, which simplifies the optical path layout and structural form of the device.

[0029] Furthermore, the dual-frequency laser is split into four beams. One beam serves as the reference signal for measurement, suppressing environmental errors and interference; another beam serves as the measurement signal along the Z-axis, enabling the measurement of the 4Z-direction displacement of the spectral dispersive confocal displacement probe; and the other two beams serve as the measurement signals along the X-axis dual optical path, enabling the measurement of the 4X-direction displacement of the spectral dispersive confocal displacement probe, while effectively compensating for the Abbe error in the measurement.

[0030] Furthermore, the spectral dispersive confocal displacement probe 4 is mounted at a certain tilt angle to the Z-axis to increase the steepness of the measurable profile.

[0031] The principle of this invention is as follows:

[0032] Based on the cylindrical coordinate measurement principle, rapid three-dimensional contour scanning measurement is achieved through a three-axis motion method. A non-contact detection of the surface contour of the object is achieved using an obliquely mounted spectral dispersive confocal displacement probe, expanding the measurable slope range. A precision interferometric displacement measurement optical path is constructed using fiber optic guidance to introduce a frequency-stabilized dual-frequency laser, enabling precise measurement of the measurement point position. A four-way beam splitting method is employed to suppress environmental errors and interference, and to compensate for Abbe errors. The device includes:

[0033] A precision air-bearing rotary table is used to fix the part to be measured and perform precision rotary motion to achieve surface contour scanning of the part. Its rotation axis is defined as the Z-axis of the measuring device.

[0034] The horizontal linear motion stage is used to perform the horizontal movement and positioning of the spectral dispersive confocal displacement probe, enabling it to scan the contour of the measured part radially, with its movement direction orthogonal to the Z-axis.

[0035] A vertical linear motion stage, mounted on a horizontal linear motion stage, is used to carry a spectral dispersive confocal displacement probe for vertical movement and positioning, with its direction of movement parallel to the Z-axis.

[0036] The controller drives the horizontal and vertical linear motion stages in tandem, controlling the spectral dispersive confocal displacement probe to scan and measure along a specified trajectory, ensuring that the contour of the measured part remains within the effective stroke range of the spectral dispersive confocal displacement probe during scanning.

[0037] The spectral dispersive confocal displacement probe is mounted on a vertical linear motion stage and is used for non-contact detection of the surface contour information of the measured part.

[0038] The laser provides a frequency-stabilized dual-frequency helium-neon laser for interferometric measurement of the two-dimensional spatial position of a spectral dispersive confocal displacement probe. The emitted laser light is transmitted via optical fiber to the vertical linear motion stage in the device.

[0039] The beam expander expands the laser beam transmitted from the optical fiber, and the expanded laser beam can be used to build an interferometric ranging optical path.

[0040] The first beam splitter is used to separate the laser into a reference beam and a measurement beam. The reference beam is used to suppress environmental errors and interference in interferometry, and the measurement beam is used to measure the displacement of the Z-axis (channel 1) and X-axis (channel 2).

[0041] The second beam splitter is used to split the laser into two beams, one for Z-axis interferometric ranging and the other for X-axis interferometric ranging.

[0042] The third beam splitter is used to split the X-axis measurement beam into two beams, with the 90° folded portion being the X-axis measurement beam 1.

[0043] The second deflector is used to redirect the laser beam transmitted through the third beam splitter by 90° to form the X-axis measurement beam 2.

[0044] The first deflector is used to deflect the laser beam reflected by the second beam splitter by 90°, and the direction of the deflected beam is parallel to the Z-axis of the device.

[0045] The third interferometer is used to perform interferometric measurements on the X-axis measurement beam 2.

[0046] The second interferometer is used to perform interferometric measurements of the X-axis measurement beam 1.

[0047] The first interferometer is used to perform interferometric measurements of Z-axis displacement.

[0048] The first beam coupler, the second beam coupler, the third beam coupler, and the fourth beam coupler are used to couple and transmit the optical signals received by the third interferometer, the second interferometer, the first interferometer, and the first beam splitter to the first receiver, the second receiver, the third receiver, and the fourth receiver, so as to realize the photoelectric conversion of the reference signal and the measurement signal.

[0049] The X-axis displacement measurement reference is fixed on a stable mechanical platform. Its plane normal is defined as the X-axis of the measuring device. As a component of the dual-frequency laser interferometric ranging optical path, it realizes the measurement of dual optical path displacement in the X direction.

[0050] The Z-axis displacement measurement reference is fixed on a stable mechanical platform, with its plane normal parallel to the Z-axis. As a component of the dual-frequency laser interferometric ranging optical path, it enables the measurement of displacement in the Z direction.

[0051] The controller is used to realize the programmed motion of the precision air-bearing rotary table, horizontal linear motion table, and vertical linear motion table, as well as the real-time acquisition, processing, and analysis and evaluation of the output signals of the precision air-bearing rotary table, horizontal linear motion table, vertical linear motion table, first receiver, second receiver, third receiver, and fourth receiver.

[0052] Compared with the prior art, the present invention has the following advantages:

[0053] (1) The use of optical fiber to transmit laser light greatly simplifies the optical path layout of the device and reduces the structural complexity.

[0054] (2) By splitting the dual-frequency laser into four optical paths, not only can the precise detection of Z-axis and X-axis displacements be achieved, but the influence of environmental errors and interference on interferometric ranging is also suppressed, and the compensation of Abbe error is realized.

[0055] (3) The contour is measured by obliquely installing a spectral dispersive confocal displacement probe, which greatly improves the slope range of the measurable contour. Attached Figure Description

[0056] Figure 1 This is a schematic diagram of an optical non-contact high-steep profile measurement device.

[0057] Figure 2 These are the three measurement modes for device scanning measurement, among which... Figure 2 (a) is the spiral scanning measurement mode. Figure 2 (b) is the radial line measurement mode. Figure 2 (c) is the concentric ring measurement mode.

[0058] Figure 3 The measurement method used by the device to measure convex and concave surfaces, wherein, Figure 3 (a) is the measurement method used by the device to measure the convex surface. Figure 3 (b) is the measurement method used by the device to measure the concave surface.

[0059] In the figure, 1 is a precision air-bearing rotary table, 2 is a horizontal linear motion stage, 3 is a vertical linear motion stage, 4 is a spectral dispersive confocal displacement probe, 5 is a laser, 6 is an optical fiber, 7 is a beam expander, 8 is a first beam splitter, 9 is a second beam splitter, 10 is a third beam splitter, 11 is a second turning mirror, 12 is a first turning mirror, 13 is a third interferometer, 14 is a second interferometer, 15 is a first interferometer, 16 is a first beam coupler, 17 is a second beam coupler, 18 is a third beam coupler, 19 is a fourth beam coupler, 20 is a first receiver, 21 is a second receiver, 22 is a third receiver, 23 is a fourth receiver, 24 is an X-axis displacement measurement reference, 25 is a Z-axis displacement measurement reference, 26 is a mechanical platform, 27 is a controller, and 28 is the part being measured. Detailed Implementation

[0060] The present invention will be further described below with reference to the accompanying drawings and specific embodiments.

[0061] like Figure 1 The diagram shows a schematic of an optical non-contact high-steepness profile measurement device, comprising a precision air-bearing rotary table 1, a horizontal linear motion stage 2, a vertical linear motion stage 3, a spectral dispersive confocal displacement probe 4, a laser 5, an optical fiber 6, a beam expander 7, a first beam splitter 8, a second beam splitter 9, a third beam splitter 10, a second deflector 11, a first deflector 12, a third interferometer 13, a second interferometer 14, a first interferometer 15, a first beam coupler 16, a second beam coupler 17, a third beam coupler 18, a fourth beam coupler 19, a first receiver 20, a second receiver 21, a third receiver 22, a fourth receiver 23, an X-axis displacement measurement reference 24, a Z-axis displacement measurement reference 25, a mechanical platform 26, and a controller 27.

[0062] The precision air-bearing rotary table 1 is horizontally fixed to the mechanical platform 26. It is used to perform the precision rotary motion of the measured part 28 and provide real-time feedback of the angle value of the rotary motion. Its rotation axis is defined as the Z-axis of the measuring device.

[0063] The horizontal linear motion stage 2, fixed to the mechanical platform 26, is used to perform the horizontal movement and positioning of the spectral dispersive confocal displacement probe 4, enabling it to scan the contour of the measured part 28 radially. The horizontal linear motion stage 2 moves in a direction orthogonal to the Z-axis, with perpendicularity on the order of arcseconds, and has positioning accuracy on the order of micrometers and motion accuracy on the order of arcseconds. Its stroke allows the dispersive confocal displacement probe 4 to cover the radial dimension range of the measured part 28.

[0064] A vertical linear motion stage 3, mounted on a horizontal linear motion stage 2, is used to carry and position a spectral dispersive confocal displacement probe 4 in the vertical direction. The vertical linear motion stage 3 moves parallel to the Z-axis, with parallelism on the order of micrometers, providing micrometer-level positioning accuracy and arcsecond-level motion accuracy. Its stroke allows the dispersive confocal displacement probe 4 to cover the sagittal range of the measured part 28.

[0065] The controller 27 drives the horizontal linear motion stage 2 and the vertical linear motion stage 3 to work together, controlling the spectral dispersive confocal displacement probe 4 to scan and measure along a specified trajectory, so that the contour of the measured part 28 is always within the effective stroke range of the spectral dispersive confocal displacement probe 4 during scanning.

[0066] The spectral dispersive confocal displacement probe 4 is mounted on a vertical linear motion stage 3. Its optical axis lies in the XZ plane and forms an angle θ with the Z-axis. The angle θ can generally be set to 2 / 3 of the maximum working tilt angle of the spectral dispersive confocal displacement probe 4, and can be appropriately increased or decreased within the maximum working tilt angle range according to measurement requirements. The spectral dispersive confocal displacement probe 4 should have a displacement resolution on the order of 10 nm and a measurement range on the order of hundreds of micrometers to meet the range and accuracy requirements of the measuring device.

[0067] Laser 5 is used to provide a frequency-stabilized dual-frequency helium-neon laser, which is coupled to polarization-maintaining fiber 6 at the laser beam exit position.

[0068] The beam expander 7 collimates and expands the laser beam transmitted and emitted by the fiber 6 to 3mm~6mm. After beam expansion, the laser direction is parallel to the Z-axis and coplanar with the XZ plane.

[0069] The first beam splitter 8 is used to separate the laser beam into a reference beam and a measurement beam. The reflected beam is received by the fourth receiver 23 as a reference signal to suppress environmental errors and interference in interferometric measurements. The transmitted beam is used to measure the displacement along the Z-axis (path 1) and X-axis (path 2). The first beam splitter 8 can generally be a non-polarizing beam splitter with a reflected beam to transmitted beam splitting ratio of 3:7.

[0070] The second beam splitter 9 is used to split the laser into two beams, one for Z-axis interferometric ranging and the other for X-axis interferometric ranging. The second beam splitter 9 can generally be a non-polarizing beam splitter with a reflected light to transmitted light splitting ratio of 3:7.

[0071] The third beam splitter 10 is used to split the X-axis measurement beam into two beams, with the 90° reflected beam being the X-axis measurement beam 1. The third beam splitter 10 can generally be a non-polarizing beam splitter with a beam splitting ratio of 1:1 between reflected and transmitted light.

[0072] The second deflector 11 is used to redirect the transmitted beam after the X-axis measurement beam is split by 90 degrees, and the redirected beam is the X-axis measurement beam 2. The direction of the redirected laser beam is parallel to the X-axis of the device.

[0073] The first deflector 12 is used to deflect the reflected laser beam from the second beam splitter 9 by 90 degrees, forming a Z-axis measurement optical path. The direction of the deflected laser beam is parallel to the Z-axis of the device.

[0074] The third interferometer 13 is used to realize the interferometric measurement of the X-axis measurement beam 2, and a single-beam interferometer is adopted.

[0075] The second interferometer 14 is used to realize the interferometric measurement of the X-axis measurement beam 1, and a single-beam interferometer is used.

[0076] The first interferometer 15 is used to realize the interferometric measurement of Z-axis displacement, and a single-beam interferometer is adopted.

[0077] The distance between X-axis measurement beam 1 and X-axis measurement beam 2 is d, and the distance between the focal point of the spectral dispersive confocal displacement probe and X-axis measurement beam 2 is s.

[0078] The first beam coupler 16, the second beam coupler 17, the third beam coupler 18, and the fourth beam coupler 19 are used to couple and transmit the optical signals received by the third interferometer 13, the second interferometer 14, the first interferometer 15, and the first beam splitter 8 to the first receiver 20, the second receiver 21, the third receiver 22, and the fourth receiver 23, so as to realize the photoelectric conversion of the reference signal and the measurement signal.

[0079] The X-axis displacement measurement reference 24 is a bar-shaped standard flat crystal with a reflective coating on its surface, fixed on a stable mechanical platform 26. The normal of the plane of the X-axis displacement measurement reference 24 is orthogonal to the Z-axis, and the perpendicularity should be controlled at the arcsecond level. The direction of the normal of the plane of the X-axis displacement measurement reference 24 is defined as the X-axis of the measuring device. As a component of the dual-frequency laser interferometric ranging optical path, it realizes the measurement of X-axis dual-optical-path displacement.

[0080] The Z-axis displacement measurement reference 25 is a bar-shaped standard flat crystal with a reflective coating on its surface, fixed on a stable mechanical platform 26. The plane normal of the Z-axis displacement measurement reference 25 is parallel to the Z-axis, and the parallelism should be controlled at the arcsecond level. The Z-axis displacement measurement reference 25 serves as a component of the dual-frequency laser interferometric ranging optical path, enabling the measurement of Z-axis displacement.

[0081] The controller 27 has motion control, data acquisition, and analysis functions. It is used to realize the programmed motion of the precision air-bearing rotary table 1, the horizontal linear motion table 2, and the vertical linear motion table 3, as well as the real-time acquisition, processing, and analysis and evaluation of the output signals of the precision air-bearing rotary table 1, the horizontal linear motion table 2, the vertical linear motion table 3, the first receiver 20, the second receiver 21, the third receiver 22, and the fourth receiver 23.

[0082] The specific steps for the device to perform measurements are as follows:

[0083] (1) Selection of measurement mode

[0084] The device uses the cylindrical coordinate measurement principle for contour measurement. The measurement modes include: spiral scanning measurement mode, radial line measurement mode, and concentric ring measurement mode, as shown below. Figure 2 (a) Figure 2 (b) Figure 2 As shown in (c).

[0085] In the spiral measurement mode, the precision air-bearing rotary table 1 maintains a constant rotational speed, the horizontal linear motion table 2 moves along the radial line at a specified speed, and the vertical linear motion table 3 follows, thus forming a spiral scanning measurement trajectory. This measurement mode is particularly suitable for rapid measurement of surfaces with continuous and basically axisymmetric contours.

[0086] In radial line measurement mode, the device scans and tests the radial profiles of the part under test 28 at different polar angles. The precision air-bearing rotary table 1 carries the part under test 28 to different polar angles, the horizontal linear motion table 2 moves along the radial line at a specified speed, and the vertical linear motion table 3 follows, acquiring the profile data of each radial line. This mode is suitable for profile measurement with large changes in height in the rotation direction, and the sampling surface density is relatively low.

[0087] In the concentric ring measurement mode, the precision air-bearing rotary table 1 maintains a constant rotational speed, while the horizontal linear motion table 2 and the vertical linear motion table 3 move according to the specified coordinate positions and stop after reaching their positions. At the same time, the device performs full-circumference sampling. This mode is suitable for high surface density measurement of surfaces that are continuous and have a basically axisymmetric profile. It can reduce the impact of dynamic errors of the motion table on the measurement, but the measurement speed is relatively slow. It usually needs to be combined with multiple radial line profile data for environmental error compensation.

[0088] (2) Setting measurement parameters

[0089] 1. Input the contour parameters of the part 28 to be measured to generate the theoretical scanning trajectory. For the measurement of convex and concave surfaces, the horizontal linear motion stage 2 should be driven to measure along the 0-degree radial line and the 180-degree radial line to increase the measurable steepness and improve accuracy. Figure 3 (a) Figure 3 As shown in (b).

[0090] 2. Based on the measurement requirements of the part 28 being measured, set the rotation speed of the precision air-bearing rotary table 1, the moving speed and range of the horizontal linear motion table 2, and the follow-up mode of the vertical linear motion table 3.

[0091] 3. Set the effective measurement area based on the dimensional information or contour boundary information of the part being measured.

[0092] 4. Set the data sampling rate, filter type, and filter parameters for the measurement process.

[0093] (3) Implementation of measurement

[0094] 1. Align the rotating shaft of the part to be tested (28) with the rotating shaft of the precision air-bearing rotary table (1);

[0095] 2. Drive the horizontal linear motion stage 2 to bring the spectral dispersive confocal displacement probe 4 to its zero reference point (which can be set to its midpoint Lc). m Located on the Z-axis, the vertical linear motion stage 3 is driven to make the zero reference point of the spectral dispersive confocal displacement probe 4 located on the surface of the part being measured 28.

[0096] 3. Drive the precision air-bearing rotary table 1, the horizontal linear motion table 2, and the vertical linear motion table 3 according to the set measurement mode and parameters, and synchronously collect the angle signal of the precision air-bearing rotary table 1 in real time. The displacement value Lc was measured by the spectral dispersive confocal displacement probe 4. i The reference axis displacement signal Lref of the laser interferometric ranging optical path i X-axis measurement beam 1 displacement signal Lx1 i X-axis measurement beam 2 displacement signal Lx2 i Z-axis displacement measurement signal measurement Lz i .

[0097] (4) Data processing

[0098] 1. Obtaining the interferometric displacement values ​​of the coordinate axes

[0099] The X-axis and Z-axis interference displacement signals Lx1 i Lx2 i Lz i Do not use with reference displacement signal Lref i Perform the subtraction to obtain the compensated X-axis measurement beam 1 displacement Lx1c i X-axis measurement beam displacement Lx2c i Z-axis displacement Lzc i .

[0100]

[0101] 2. Compensation for Abbe error

[0102] Based on the initial state, the displacement values ​​corresponding to X-axis measurement beam 1 and X-axis measurement beam 2 are Lx1c0 and Lx2c0, respectively. During the measurement process, the displacement values ​​corresponding to X-axis measurement beam 1 and X-axis measurement beam 2 are Lx1c0 and Lx2c0, respectively. i Lx2c i .

[0103] During the measurement process, the X-axis displacement Lx at the focal point of the spectral dispersive confocal displacement probe 4 is determined. i The calculation formula is:

[0104] Lx i =Lx2c i -((Lx1c i -Lx2c i )-(Lx1c0-Lx2c0))*s / d

[0105] 3. Coordinate value calculation

[0106] Based on the measurement principle, system geometric parameters, and acquired displacement information, calculate the coordinate values ​​(x, y, y) corresponding to the surface sampling points. i y i , z i ):

[0107]

[0108] Among them, Lc i The reading is for the spectral dispersive confocal displacement probe 4.

[0109] 4. Based on the calculated discrete coordinate points, calculate the contour error through model comparison or fitting.

[0110] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any transformations or substitutions that can be conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the scope of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. An optical non-contact high-steepness profile measuring device, characterized in that, include: The system comprises a precision air-bearing rotary stage (1), a horizontal linear motion stage (2), a vertical linear motion stage (3), a spectral dispersive confocal displacement probe (4), a laser (5), an optical fiber (6), a beam expander (7), a first beam splitter (8), a second beam splitter (9), a third beam splitter (10), a second conversion mirror (11), a first conversion mirror (12), a third interferometer (13), a second interferometer (14), a first interferometer (15), a first beam coupler (16), a second beam coupler (17), a third beam coupler (18), a fourth beam coupler (19), a first receiver (20), a second receiver (21), a third receiver (22), a fourth receiver (23), an X-axis displacement measurement reference (24), a Z-axis displacement measurement reference (25), a mechanical platform (26), and a controller (27). The precision air-bearing rotary table (1) is used to fix the part to be measured (28) and perform precision rotary motion to realize the surface contour scanning of the part to be measured. Its rotation axis is defined as the Z-axis of the measuring device. The horizontal linear motion stage (2) is used to perform the horizontal movement and positioning of the spectral dispersive confocal displacement probe (4), so that it can scan the contour of the measured part (28) radially, and its movement direction is orthogonal to the Z-axis; The vertical linear motion stage (3) is installed on the horizontal linear motion stage (2) and is used to carry the spectral dispersive confocal displacement probe (4) to move and position in the vertical direction. Its movement direction is parallel to the Z-axis. The controller (27) drives the horizontal linear motion stage (2) and the vertical linear motion stage (3) to work together to control the spectral dispersive confocal displacement probe (4) to scan and measure along the specified trajectory, so that the contour of the part under test (28) is always within the effective stroke range of the spectral dispersive confocal displacement probe (4) during scanning. The spectral dispersive confocal displacement probe (4) is mounted on the vertical linear motion stage (3) and is used for non-contact detection of the surface contour information of the part (28) being measured. The laser (5) is used to provide a frequency-stabilized dual-frequency helium-neon laser for interferometric measurement of the two-dimensional spatial position of the spectral dispersive confocal displacement probe (4). The laser emitted from the laser (5) is transmitted by the optical fiber (6) to the vertical linear motion stage (3) in the device. The beam expander (7) expands the laser beam transmitted from the optical fiber (6), and the expanded laser beam can be used to build an interferometric ranging optical path; The first beam splitter (8) is used to separate the laser into a reference beam and a measurement beam. The reference beam is used to suppress environmental errors and interference in interferometric measurements, and the measurement beam is used to realize the measurement of displacement along the Z-axis and X-axis. The second beam splitter (9) is used to split the laser into two beams, one for Z-axis interference ranging and the other for X-axis interference ranging. The third beam splitter (10) is used to split the X-axis measurement beam into two beams, of which the 90° folded part of the beam is the X-axis measurement beam 1; The second turning mirror (11) is used to turn the laser beam transmitted through the third beam splitter (10) by 90° to form the X-axis measurement beam 2; The first turning mirror (12) is used to turn the laser beam reflected by the second beam splitter (9) by 90°, and the direction of the beam after turning is parallel to the Z-axis of the device. The third interferometer (13) is used to realize the interferometric measurement of the X-axis measurement beam 2; The second interferometer (14) is used to realize the interferometric measurement of the X-axis measurement beam 1; The first interferometer (15) is used to realize the interferometric measurement of Z-axis displacement; The first beam coupler (16), the second beam coupler (17), the third beam coupler (18), and the fourth beam coupler (19) are used to receive, couple, and transmit the optical signals from the third interferometer (13), the second interferometer (14), the first interferometer (15), and the first beam splitter (8) to the first receiver (20), the second receiver (21), the third receiver (22), and the fourth receiver (23) to achieve photoelectric conversion of the reference signal and the measurement signal. The X-axis displacement measurement reference (24) is fixed on a stable mechanical platform (26), and its plane normal is defined as the X-axis of the measuring device. As a component of the dual-frequency laser interferometric ranging optical path, it realizes the measurement of the X-direction dual optical path displacement. The Z-axis displacement measurement reference (25) is fixed on a stable mechanical platform (26), and its plane normal is parallel to the Z-axis. As a component of the dual-frequency laser interferometric ranging optical path, it realizes the measurement of displacement in the Z direction. The controller (27) is used to realize the programmed motion of the precision air-bearing rotary table (1), the horizontal linear motion table (2), the vertical linear motion table (3), and the real-time acquisition, processing, and analysis and evaluation of the output signals of the precision air-bearing rotary table (1), the horizontal linear motion table (2), the vertical linear motion table (3), the first receiver (20), the second receiver (21), the third receiver (22), and the fourth receiver (23).

2. An optical non-contact high-steep profile measuring device according to claim 1, characterized in that, The laser emitted by the laser (5) is introduced into the measurement optical path by optical fiber transmission, which simplifies the optical path layout and structure of the device.

3. An optical non-contact high-steep profile measuring device according to claim 1, characterized in that, The dual-frequency laser is divided into four beams. One beam serves as the reference signal for measurement, suppressing environmental errors and interference. Another beam serves as the measurement signal for the Z-axis, enabling the measurement of the Z-direction displacement of the spectral dispersive confocal displacement probe (4). The other two beams serve as the measurement signals for the X-axis dual optical path, enabling the measurement of the X-direction displacement of the spectral dispersive confocal displacement probe (4), while effectively compensating for the Abbe error in the measurement.

4. An optical non-contact high-steep profile measuring device according to claim 1, characterized in that, The spectral dispersive confocal displacement probe (4) is installed at a certain tilt angle with the Z-axis to increase the steepness of the measurable profile.

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