Continuous zoom wide-spectrum interference micrometer device

Abstract

The invention discloses a continuous zoom wide-spectrum interference micrometer device which comprises a wide-spectrum light source, a reticle, an optical lens group, an objective lens group, a spectroscope, a continuous zoom lens group, a camera, a displacement table, a displacement table controller and a calculation unit. The optical lens group is used for converging light beams emitted by the wide-spectrum light source into parallel light beams, the spectroscope is used for reflecting the parallel light beams and penetrating interference light beams, and the interference light beams penetrate through the spectroscope and are converged by the continuous zoom lens group and the camera to form interference images; the continuous zoom lens group consists of a plurality of groups of lenses, and the distance between the lenses can be changed through movement, so that the focal length can be continuously changed, and the continuous zoom and the variable view field can be realized; and the calculation unit is used for calculating the longitudinal height of the measured surface according to the series of interference images and reconstructing the three-dimensional shape of the measured surface. The invention has the advantages of high precision, continuously variable focal length, continuously variable magnification, continuously variable field of view, light weight and small volume.

Description

Technical Field

[0001] The invention belongs to the field of optics, and in particular relates to a continuously variable magnification wide spectrum interference micrometer device. Background Art

[0002] The industrial field has put forward an urgent demand for non-contact measurement technology. In the fields of semiconductors, aerospace, etc., high-precision three-dimensional morphology detection technology at the micron to nanometer level has become an important development direction. In the field of non-contact optical detection, there are mainly imaging vertical scanning measuring instruments, scanning confocal scanning devices, plane interferometers, multi-focal plane superposition measuring instruments, white light interferometer scanners, etc. These non-contact optical measurement technologies have advantages over contact measurement methods such as high measurement accuracy and fast speed.

[0003] The wide-spectrum interferometry device is a precision aiming and measuring tool for measuring three-dimensional contours, flatness, and roughness. It can obtain a series of interference patterns of the measured surface, which are used to aim and measure different positions and heights in the longitudinal direction (direction of the main optical axis). The wide-spectrum interferometry device uses the low coherence of the wide spectrum to achieve high-precision, high-resolution aiming, positioning and measurement of micro-nano-sized devices through the zero-order fringes of interference. However, the existing wide-spectrum interferometry technology has problems such as fixed magnification, fixed focal length, high cost, complex structure, equipped with a series of objective lenses, large size, and low precision. Summary of the invention

[0004] The purpose of the present invention is to provide a high-precision, continuously variable focal length, continuously variable magnification, continuously variable field of view, light weight, and small size continuously variable wide spectrum interferometry micrometer with regard to the problems existing in the prior art.

[0005] In order to achieve the above-mentioned object, one aspect of the present invention provides a continuously variable magnification wide spectrum interferometry device, comprising a wide spectrum light source, a graticule, an optical lens group, an objective lens group, a beam splitter, a continuously variable magnification lens group, a camera, a translation stage, a translation stage controller and a computing unit;

[0006] The wide-spectrum light source is used for illumination and as an interference light source. The graticule is arranged between the wide-spectrum light source and the optical lens group, and is used for displaying the magnification and dividing the regions of different fields of view in the case of continuous zooming. The optical lens group is used for converging the light beams emitted from the wide-spectrum light source into parallel light beams. The beam splitter is used for reflecting the parallel light beams and transmitting the interference light beams. The parallel light beams reflected by the beam splitter are converged to the measured surface through the objective lens group and form interference light beams with the reflected light of the measured surface and generate interference fringes in the objective lens group. The interference light beams pass through the beam splitter and are converged by the continuous zoom lens group and the camera to form an interference image.

[0007] The continuous zoom lens group is composed of multiple groups of lenses, and can change the spacing between the lenses by movement to achieve continuous change of focal length, thereby achieving continuous zoom and variable field of view. The translation stage is used for longitudinal movement to achieve scanning measurement of the measured surface, thereby obtaining a series of interference images. The translation stage controller is used to control the movement of the translation stage under the control of a computing unit, and the computing unit is used to calculate the longitudinal height of the measured surface according to the series of interference images and reconstruct the three-dimensional morphology of the measured surface.

[0008] Preferably, the computing unit is used to convert the interference image into a light intensity map, obtain the modulation map of each interference image through filtering and signal extraction algorithms, obtain the height information of each pixel point of the measured surface through solving, and realize the three-dimensional morphology reconstruction of the measured surface.

[0009] Preferably, the broad spectrum light source is a white light source or a low coherence light source, and the graticule is a line graticule or a concentric circle graticule.

[0010] Preferably, the beam splitter comprises a beam splitter plate, a beam splitter prism, a polarizing beam splitter and a non-polarizing beam splitter.

[0011] Preferably, the optical lens group and the objective lens group are visible light band coated optical lens groups.

[0012] Preferably, the displacement stage is a micro-nano displacement stage controlled by piezoelectric ceramics or a micro-nano displacement stage controlled by a stepping motor.

[0013] Preferably, the continuous zoom lens assembly changes the focal length by changing the curvature or applying pressure to change the refractive index of the material.

[0014] Preferably, the continuous zoom is 0.5 to 1000 times continuous zoom, and the range of the field of view includes the central field of view, 1 / 3 of the full field of view, 2 / 3 of the full field of view and the full field of view range.

[0015] Preferably, by arranging and combining each position of each lens, the optimal aberration solution at the same magnification is listed, so as to obtain the position of each lens at the corresponding magnification, and then obtain the spacing value between the lenses.

[0016] The continuously variable wide spectrum interferometry device of the present invention has the advantages of high precision, continuously variable focal length, continuously variable magnification, continuously variable field of view, light weight and small size. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the technical solution of the present invention, the following briefly introduces the drawings used in the description of the embodiments of the present invention. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative work:

[0018] Figure 1 is a schematic structural diagram of a continuously variable wide spectrum interferometry device according to an embodiment of the present invention,

[0019] Figure 2 This is a schematic diagram of a continuously variable magnification wide spectrum interferometry device according to an embodiment of the present invention;

[0020] Figure 3 This is an interference fringe pattern obtained by a continuously variable magnification wide spectrum interferometry micrometer according to an embodiment of the present invention. DETAILED DESCRIPTION

[0021] In order to make the purpose, technical solution and advantages of the present invention clearer, the technical solution of the present invention will be clearly and completely described 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.

[0022] One embodiment of the present invention provides a continuously variable wide spectrum interferometer micrometer, such as Figure 1 As shown, the continuously variable magnification wide spectrum interferometry device of the embodiment of the present invention includes a wide spectrum light source 1, a graticule 2, an optical lens group 3, an objective lens group 4, a translation stage 5, a beam splitter 6, a continuously variable magnification lens group 7, a camera 8, a translation stage controller 9 and a computing unit 10.

[0023] The wide spectrum light source 1 is located at the front end of the optical path, and is used for illumination and acting as an interference light source. The wide spectrum light source 1 is a light source of non-single spectrum. Optionally, the wide spectrum light source 1 is a white light source with a central wavelength of 560nm. During the actual measurement process, the brightness can be flexibly changed by the control circuit. The wide spectrum light source 1 is not limited to a white light source, and a wide spectrum light source such as a low coherence light source can be used. Optionally, the wide spectrum light source 1 is a full spectrum light source. The wide spectrum light source 1 is preferably an LED or OLED series light source, but is not limited thereto. Optionally, the wide spectrum light source 1 is a fiber optic light source, which can be a DC voltage-regulated fiber optic light source.

[0024] The graticule 2 is used as a marker (line pattern), and the graticule includes but is not limited to a crosshair-shaped line graticule, and may also be a concentric circle graticule, etc., which is used to display the magnification and divide the area of ​​different field of view ranges during continuous zooming.

[0025] The optical lens group 3 and the objective lens group 4 are respectively used for converging the light beams emitted from the wide spectrum light source 1 and generating interference fringes. The beam splitter 6 is used for reflecting the light beams emitted from the wide spectrum light source 1 and the interference light beams reflected by the measured surface. The beam splitter 6 includes but is not limited to a beam splitter plate, a beam splitter prism, a polarizing beam splitter, a non-polarizing beam splitter, etc. The beam splitter 6 is preferably a beam splitter prism. The beam splitter prism can be a cubic beam splitter prism.

[0026] The light emitted by the wide spectrum light source 1 passes through the optical lens group 3 to form a parallel light beam and is reflected by the beam splitter 6. After passing through the objective lens group 4, it converges to the measured surface and forms an interference light beam with the reflected light and generates interference fringes in the objective lens group 4. The interference light beam passes through the beam splitter 6 and is converged by the continuous zoom lens group 7 and the camera 8 to form an image. The objective lens group 4 includes but is not limited to a fixed focal length objective lens group. Preferably, the optical lens group 3 and the objective lens group 4 are optical lens groups coated in the visible light band.

[0027] The displacement stage 5 and the displacement stage controller 9 are used for movement and control along the light propagation direction. The displacement stage 5 is used for longitudinal movement to realize scanning measurement of the measured surface. For each independent longitudinal scanning position, a series of interference images are collected through corresponding scanning movement. The displacement stage controller 9 is used to control the movement of the displacement stage 5 under the control of the calculation unit 10. Optionally, the displacement stage 5 is a micro-nano displacement stage controlled by piezoelectric ceramics, and the resolution can reach ±1nm. The displacement stage 5 can also be a micro-nano displacement stage controlled by a stepping motor.

[0028] The continuous zoom lens group 7 uses a zooming method to achieve continuous zoom imaging of the target, and realizes continuous change of the field of view and magnification. The continuous zoom lens group 7 is composed of multiple groups of lenses, such as Figure 2 As shown in the figure, by changing the distance between the lenses, the focal length can be continuously changed, thereby achieving continuous magnification and field of view. Figure 3 The interference diagrams at the maximum and minimum magnifications under continuous magnification are shown. Camera 8 is an industrial CCD camera or CMOS camera for digital imaging and display. The industrial CCD camera can be an industrial low-light response CCD camera.

[0029] The continuous zoom lens group 7 is composed of a single lens or a double-cemented lens, which plays three roles in converging light, adjusting the focal length, and compensating for aberrations. The overall continuous zoom and variable field of view requirements are achieved by changing the spacing between multiple groups of lenses. The spacing calculation is calculated in a global range. Each position of each lens is arranged and combined, and the optimal solution of aberrations under the same magnification is listed to obtain the position of each lens under the corresponding magnification, and then the lens spacing value is obtained. Each continuous magnification is calculated to obtain the position of each corresponding lens and thus the spacing between the lenses. The zoom range of the continuous zoom lens group 7 includes but is not limited to continuous zoom, and any zoom ratio within the zoom range can also be selected. The spacing between the lenses includes but is not limited to the spacing of linear positions, and also includes the spacing of non-linear positions.

[0030] Optionally, the continuous zoom lens group 7 is composed of multiple groups of lenses, and the focal length can be changed by mechanical zooming methods such as changing the curvature and changing the refractive index of the material by applying pressure, thereby achieving continuous zoom and variable field of view. The continuous zoom is 0.5 times to 1000 times continuous zoom, but is not limited to 0.5 times to 1000 times continuous zoom. Preferably, the continuous zoom range is 0.5 times to 120 times continuously variable. The field of view range applicable to aiming, measuring, and observing includes but is not limited to the central field of view, 1 / 3 of the full field of view, 2 / 3 of the full field of view, and the full field of view range. Preferably, the field of view for observation application is the full field of view range, and the field of view range for aiming and measuring application is 1 / 3 of the full field of view range.

[0031] The calculation unit 10 is used to save the obtained series of interference images and calculate the longitudinal height of the measured surface by an algorithm and reconstruct the three-dimensional shape of the measured surface. Specifically, the calculation unit 10 converts the obtained interference grayscale image into a light intensity image, obtains the modulation image of a single interference image through filtering and signal extraction algorithms, and obtains the height information of each pixel point on the surface of the measured object through solution, thereby realizing the aiming, measurement and three-dimensional shape reconstruction of the measured micro-size.

[0032] Specifically, the coordinate values ​​of the x / y position are obtained by solving the obtained image pixel points, and the z coordinate corresponding to the longitudinal direction is obtained by solving the interference image fringes, thereby obtaining the z-direction position coordinates of each pixel point in the full field of view, and then reconstructing the entire three-dimensional appearance. The solving algorithm includes but is not limited to any interference fringe displacement solving algorithm such as four-step phase shifting and nine-step phase shifting.

[0033] The continuously variable wide spectrum interferometry measurement device of the embodiment of the present invention utilizes the combined effect of light intensity and modulation for detection, which can effectively eliminate the influence of factors such as unstable light intensity of the light source and external disordered disturbances. It has the characteristics of high measurement accuracy, strong anti-interference ability, small system structure, and light weight. It is suitable for micro-nano-size aiming, observation, measurement and three-dimensional morphology detection, and has the characteristics of strong practicality and high measurement stability.

[0034] The continuously variable magnification wide spectrum interferometry micrometer of the embodiment of the present invention can be placed vertically, with the measured surface placed perpendicular to the principal optical axis (the direction of light propagation) and moved along the principal optical axis to complete three-dimensional scanning measurement, but is not limited to vertical placement, and can also be placed horizontally, and is not limited to movement along the principal optical axis and three-dimensional measurement.

[0035] Preferably, the total weight of the wide-spectrum light source 1, the optical lens group 3, the continuous zoom lens group 7, the graticule 2, the beam splitter 6, the camera 8, the translation stage 5, and the objective lens group 4 does not exceed 10 kg.

[0036] The continuously variable magnification wide spectrum interferometry device of the embodiment of the present invention can achieve a very nanometer-level longitudinal resolution on the one hand, and on the other hand, the field of view is adjustable. While meeting the accuracy requirements, it is especially aimed at high-precision micro-nano structure size detection, and has the characteristics of high measurement accuracy and can achieve miniaturization, small volume, and small mass of the device.

[0037] Of course, in the embodiment of the present invention, the external vibration amplitude, frequency and disturbance, and the light intensity fluctuation amplitude of the light source need to be strictly controlled within a certain numerical range, so that high-precision and high-stability measurements can be completed to the greatest extent. The three-dimensional morphology reconstruction algorithm can also be continuously optimized to better adapt to various complex measurement environments.

[0038] The continuously variable wide spectrum interferometry measuring device of the embodiment of the present invention can be used as a separate aiming and positioning measuring device for measurement; it can also be used as a part of other instruments, such as a three-coordinate measuring machine, to realize the aiming and measuring function, and has the following beneficial effects:

[0039] 1. The present invention uses a zoom method to achieve continuous zooming and magnification through a sophisticated optical path structure design, and obtains white light interference images at different magnifications, thereby achieving measurement of different micro-sizes and reconstruction of three-dimensional surface morphology;

[0040] 2. The present invention adopts a wide spectrum as a light source and can be used as a single instrument or as part of other instruments in combination;

[0041] 3. The overall structure of the present invention is compact, light, small, and low in cost. Since continuous zooming is achieved, a single magnification objective lens can be used to achieve continuous zooming of 0.5 to 1000 times magnification, overcoming the shortcomings of traditional wide-spectrum interferometry devices, such as large size, heavy weight, and high price of a series of fixed-focus objective lenses.

[0042] The above description is only by way of illustration of certain exemplary embodiments of the present invention. It is undoubted that those skilled in the art can modify the described embodiments in various ways without departing from the spirit and scope of the present invention. Therefore, the above drawings and descriptions are illustrative in nature and should not be construed as limiting the scope of protection of the claims of the present invention.

Claims

1. A continuously variable wide spectrum interferometry device, characterized in that: It includes a wide spectrum light source, a graticule, an optical lens group, an objective lens group, a beam splitter, a continuous zoom lens group, a camera, a translation stage, a translation stage controller and a computing unit; The wide-spectrum light source is used for illumination and as an interference light source. The graticule is arranged between the wide-spectrum light source and the optical lens group, and is used for displaying the magnification and dividing the regions of different fields of view in the case of continuous zooming. The optical lens group is used for converging the light beams emitted from the wide-spectrum light source into parallel light beams. The beam splitter is used for reflecting the parallel light beams and transmitting the interference light beams. The parallel light beams reflected by the beam splitter are converged to the measured surface through the objective lens group and form interference light beams with the reflected light of the measured surface and generate interference fringes in the objective lens group. The interference light beams pass through the beam splitter and are converged by the continuous zoom lens group and the camera to form an interference image. The continuous zoom lens group is composed of multiple groups of lenses, and can change the spacing between the lenses by movement to achieve continuous change of focal length, thereby achieving continuous zoom and variable field of view. The translation stage is used for longitudinal movement to achieve scanning measurement of the measured surface, thereby obtaining a series of interference images. The translation stage controller is used to control the movement of the translation stage under the control of a computing unit, and the computing unit is used to calculate the longitudinal height of the measured surface according to the series of interference images and reconstruct the three-dimensional morphology of the measured surface.

2. The continuously variable wide spectrum interferometry device according to claim 1, characterized in that: The calculation unit is used to convert the interference image into a light intensity map, obtain the modulation map of each interference image through filtering and signal extraction algorithms, obtain the height information of each pixel point of the measured surface through solution, and realize the three-dimensional morphology reconstruction of the measured surface.

3. The continuously variable wide spectrum interferometry device according to claim 1 or 2, characterized in that: The wide spectrum light source is a white light source or a low coherence light source, and the graticule is a line graticule or a concentric circle graticule.

4. The continuously variable wide spectrum interferometry device according to claim 1 or 2, characterized in that: The beam splitter includes a beam splitter plate, a beam splitter prism, a polarization beam splitter and a non-polarization beam splitter.

5. The continuously variable wide spectrum interferometry device according to claim 1 or 2, characterized in that: The optical lens group and the objective lens group are visible light band coated optical lens groups.

6. The continuously variable wide spectrum interferometry device according to claim 1 or 2, characterized in that: The displacement stage is a micro-nano displacement stage controlled by piezoelectric ceramics or a micro-nano displacement stage controlled by a stepping motor.

7. The continuously variable wide spectrum interferometry device according to claim 1 or 2, characterized in that: The continuous zoom lens group changes the focal length by changing the curvature or applying pressure to change the refractive index of the material.

8. The continuously variable wide spectrum interferometry device according to claim 1 or 2, characterized in that: The continuous zooming is from 0.5 times to 1000 times, and the range of the field of view includes the central field of view, 1 / 3 of the full field of view, 2 / 3 of the full field of view and the full field of view range.

9. The continuously variable wide spectrum interferometry device according to claim 1 or 2, characterized in that: By arranging and combining each position of each lens and listing the optimal aberration solutions at the same magnification, the position of each lens at the corresponding magnification is obtained, and then the spacing value between the lenses is obtained.

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