CN115371587A - Surface topography measuring device and method and object surface height calculating method - Google Patents
Surface topography measuring device and method and object surface height calculating method Download PDFInfo
- Publication number
- CN115371587A CN115371587A CN202211020203.8A CN202211020203A CN115371587A CN 115371587 A CN115371587 A CN 115371587A CN 202211020203 A CN202211020203 A CN 202211020203A CN 115371587 A CN115371587 A CN 115371587A
- Authority
- CN
- China
- Prior art keywords
- optical fiber
- displacement
- measured
- displacement table
- dimensional
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Pending
Links
Images
Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
- G01B11/00—Measuring arrangements characterised by the use of optical techniques
- G01B11/24—Measuring arrangements characterised by the use of optical techniques for measuring contours or curvatures
- G01B11/2441—Measuring arrangements characterised by the use of optical techniques for measuring contours or curvatures using interferometry
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
- G01B11/00—Measuring arrangements characterised by the use of optical techniques
- G01B11/02—Measuring arrangements characterised by the use of optical techniques for measuring length, width or thickness
- G01B11/06—Measuring arrangements characterised by the use of optical techniques for measuring length, width or thickness for measuring thickness ; e.g. of sheet material
- G01B11/0608—Height gauges
Abstract
The application provides a surface topography measuring device and method, object surface height calculating method, is applied to the optical precision measurement technical field, including: the optical fiber F-P interference measuring head and the three-dimensional displacement platform; the optical fiber F-P interference measuring head consists of an optical fiber head array and a micro lens array, and an object to be measured is fixed on the three-dimensional displacement table; the light beam is transmitted to the optical fiber F-P interference measuring head, is emitted from the emergent surface of the micro lens array after passing through the optical fiber head array and the micro lens array, and is collimated and irradiated to the surface of the object to be measured; the three-dimensional displacement platform drives the object to be measured to do three-dimensional motion so as to measure the surface appearance of the object to be measured. By adopting a scanning measurement scheme combining the optical fiber head array, the micro lens array and the three-dimensional displacement table, the problems of small measurement range and low measurement speed of the optical fiber F-P interference measuring head are solved, the measurement range and the measurement speed of an optical fiber F-P interference surface morphology detection product are improved, and the cost is reduced.
Description
Technical Field
The application relates to the technical field of optical precision measurement, in particular to a surface topography measuring device and method and an object surface height calculating method.
Background
With the rapid development of the precision equipment processing and manufacturing industry, the surface topography measurement has important application in the production processes of element size measurement, element surface defect measurement, quality control and the like, and the optical non-contact measurement based on optical detection becomes a research and application hotspot in the field of surface topography measurement by virtue of the advantages of high measurement precision, wide application range of measurement objects, convenience in automation, modularization and the like.
In the optical non-contact measurement method, compared with the traditional interferometer with a lens combination, the optical fiber interferometer with the all-fiber structure has the advantages of compact and flexible structure, high sensitivity and strong environmental adaptability. Common optical fiber interferometers include an optical fiber mach-zehnder interferometer, an optical fiber michelson interferometer and an optical fiber F-P interferometer (Fabry-perot interferometer), wherein the optical fiber mach-zehnder interferometer and the optical fiber michelson interferometer have the problems of complex system structure and need of setting a reference arm in the application of surface topography measurement due to the structure of a light splitting path, and are not beneficial to the integration of a surface topography detection system. The optical fiber F-P interferometer is a common-path structure interferometer, and the working principle of the optical fiber F-P interferometer is that the phase change of an F-P cavity interference field is changed by changing the length of an F-P cavity. Due to the unique working principle and the common-path structure of the F-P interferometer, the optical fiber F-P interferometer applied to displacement measurement has the advantages of high sensitivity, strong stability and simple structure.
However, at present, the optical fiber F-P interferometer is generally applied to scenes such as one-dimensional displacement measurement, object micro-vibration measurement and the like, the optical fiber F-P interferometer is not applied to three-dimensional surface topography measurement, and meanwhile, the traditional intensity demodulation optical fiber F-P interferometer also has the problems of small measurement range and low stability.
Therefore, a new technical solution for applying the fiber-optic F-P interferometer to three-dimensional surface topography measurement is needed.
Disclosure of Invention
In view of this, embodiments of the present disclosure provide a surface topography measurement apparatus and method, and an object surface height calculation method, so as to solve technical problems of a distance measurement principle scheme of an optical fiber F-P interferometric probe in the prior art, such as low precision, poor stability, a small measurement range, and a slow measurement speed.
The embodiment of the specification provides the following technical scheme:
an embodiment of the present specification provides a surface topography measurement apparatus, including: the optical fiber F-P interference measuring head and the three-dimensional displacement platform;
the optical fiber F-P interference measuring head consists of an optical fiber head array and a micro lens array, and an object to be measured is fixed on the three-dimensional displacement table;
the light beam is transmitted to the optical fiber F-P interference measuring head, is emitted from the emergent surface of the micro lens array after passing through the optical fiber head array and the micro lens array, and is collimated and irradiated to the surface of the object to be measured;
the three-dimensional displacement platform drives the object to be measured to do three-dimensional motion so as to measure the surface appearance of the object to be measured.
Preferably, the microlens array is composed of a plurality of microlens units side by side;
the emergent surface of each micro lens unit and the corresponding reflection area on the surface of the object to be measured form an F-P cavity.
Preferably, the optical fiber head array is opposite to the incidence surface of the microlens unit, the optical fiber head array is composed of a plurality of optical fiber units, and the plurality of optical fiber units correspond to the plurality of microlens units one to one.
Preferably, each optical fiber unit includes an optical fiber, a protection tube, and a round table;
the optical fiber is welded with the small cylindrical surface of the circular truncated cone, and the protection tube is welded with the large cylindrical surface of the circular truncated cone;
the circular arc surface of the circular truncated cone is opposite to the incident surface of the micro lens unit.
Preferably, the three-dimensional displacement stage comprises a first displacement stage, a second displacement stage and a third displacement stage;
the first displacement table is fixedly connected with the second displacement table, the object to be detected is fixed on the first displacement table, and the optical fiber head array and the micro-lens array are fixed on the third displacement table;
the first displacement table and the second displacement table control the object to be measured to perform two-dimensional motion in the first plane, and the third displacement table controls the optical fiber head array and the micro-lens array to perform one-dimensional motion in the direction perpendicular to the first plane.
Preferably, the method further comprises the following steps: the device comprises a laser, an optical fiber beam combiner, an optical fiber circulator, a displacement table control upper computer, a spectrometer and a computer;
the laser is a broadband light source and is used for outputting laser;
laser is divided into a plurality of light beams by an optical fiber beam combiner, the light beams are transmitted to an optical fiber F-P interference measuring head after passing through an optical fiber circulator, the light beams are transmitted to the optical fiber F-P interference measuring head, emitted from the emergent surface of a micro lens array, collimated and irradiated on the surface of an object to be measured, reflected back and forth between the surface of the object to be measured and the emergent surface of the micro lens array, a multi-beam interference field is formed in a plurality of F-P cavities, and the reflected part of the multi-beam interference field is transmitted to a spectrometer through the optical fiber circulator;
the three-dimensional displacement table carries out displacement real-time detection through a displacement sensor and feeds displacement data back to a displacement table control upper computer in real time, the displacement table control upper computer controls the three-dimensional displacement table to carry out three-dimensional motion through the displacement data and a preset motion track and feeds motion data of the three-dimensional motion back to a computer;
and the computer controls the motion data fed back by the upper computer and the spectrum data on the spectrometer according to the displacement table to finish the surface appearance measurement of the object to be measured.
An embodiment of the present disclosure further provides a surface topography measurement method, which is applicable to the surface topography measurement apparatus described above, and includes:
laser emitted by a laser is divided into a plurality of light beams by an optical fiber beam combiner, the light beams are transmitted to an optical fiber F-P interference measuring head after passing through an optical fiber circulator, are emitted from an emergent surface of a micro-lens array, are collimated and irradiated onto the surface of an object to be measured, and are reflected back and forth between the surface of the object to be measured and the emergent surface of the micro-lens array, a multi-beam interference field is formed in a plurality of F-P cavities, the reflection part of the multi-beam interference field is transmitted to a spectrometer through the optical fiber circulator, and the emergent surface of each micro-lens unit in the micro-lens array and the reflection area on the surface of the corresponding object to be measured form the F-P cavity;
the three-dimensional displacement table carries out displacement real-time detection through a displacement sensor and feeds displacement data back to a displacement table control upper computer in real time, the displacement table control upper computer controls the three-dimensional displacement table to carry out three-dimensional motion through the displacement data and a preset motion track and feeds motion data of the three-dimensional motion back to a computer;
and the computer controls the motion data fed back by the upper computer and the spectrum data on the spectrometer according to the displacement table to finish the surface appearance measurement of the object to be measured.
Preferably, the three-dimensional displacement platform comprises a first displacement platform, a second displacement platform and a third displacement platform, comprising:
adjusting the first displacement table and the second displacement table to enable the micro-lens array to irradiate on an initial sampling point of the object to be detected, and adjusting the relative position of the optical fiber F-P interference measuring head and the object to be detected through the third displacement table to obtain a first distance between the optical fiber F-P interference measuring head and the object to be detected at the initial sampling point;
the third displacement table is kept unchanged, the object to be measured is driven by the first displacement table to perform continuous one-dimensional motion in the second direction, first cavity length data of the F-P cavity at each moment in the one-dimensional motion are calculated through spectral data in the one-dimensional motion process, and the second distance of each sampling point on the surface of the object to be measured in the second direction relative to the initial sampling point is obtained according to the first cavity length data and the first distance;
the third displacement table is kept unchanged, the object to be measured is driven by the second displacement table to perform continuous one-dimensional motion in the first direction, second cavity length data of the F-P cavity at each moment in the one-dimensional motion are calculated through spectrum data in the one-dimensional motion, and according to the second cavity length data and the first distance, a third distance of each sampling point of the surface of the object to be measured in the first direction relative to the initial sampling point is obtained;
and finishing the surface topography measurement of the object to be measured according to the first distance, the second distance and the third distance.
Preferably, in the process that the object to be measured makes continuous one-dimensional motion in the second direction under the drive of the first displacement table and the object to be measured makes continuous one-dimensional motion in the first direction under the drive of the second displacement table, the cavity length of an F-P cavity formed by the surface of the object to be measured and the optical fiber F-P interference measuring head changes.
The embodiment of the present specification further provides an object surface height calculation method, which is applied to the surface topography measurement method, and includes:
step 1: obtaining an interference pattern according to the initial reflection spectrum of the F-P cavity, tracking and recording the central wavelength of a resonance peak in the interference pattern, wherein the exit surface of each micro lens unit in the micro lens array and the corresponding reflection area on the surface of the object to be detected form the F-P cavity;
step 2: calibrating the cavity length variation of the F-P cavity and the wavelength variation of the center wavelength of the resonance peak to obtain the corresponding relation between the cavity length variation and the wavelength variation;
and 3, step 3: obtaining the cavity length variation of the F-P cavity according to the wavelength variation and the corresponding relation in the measurement process of the object to be measured;
and 4, step 4: and obtaining the surface height of the object to be measured according to the cavity length variation.
Compared with the prior art, the beneficial effects that can be achieved by the at least one technical scheme adopted by the embodiment of the specification at least comprise: the measuring head distance measuring scheme adopting spectrum demodulation solves the problems of lower precision and poorer stability of an optical fiber F-P interference measuring head distance measuring principle scheme in the prior art, improves the distance measuring precision and the environmental stability of an optical fiber F-P interference surface morphology detection product, solves the problems of small measuring range and low measuring speed of the optical fiber F-P interference measuring head by adopting a scanning measuring scheme combining an optical fiber head array, a micro lens array and a three-dimensional displacement table, improves the measuring range and the measuring speed of the optical fiber F-P interference surface morphology detection product, and reduces the cost of the optical fiber F-P interference surface morphology detection product.
Drawings
In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings needed to be used in the embodiments will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present application, and it is obvious for those skilled in the art to obtain other drawings based on these drawings without creative efforts.
FIG. 1 is a schematic structural diagram of a surface topography measurement apparatus provided in an embodiment of the present application;
fig. 2 is a schematic structural diagram of an optical fiber F-P interference probe according to an embodiment of the present disclosure;
fig. 3 is a schematic structural diagram of a fiber head unit according to an embodiment of the present disclosure.
Detailed Description
The embodiments of the present application will be described in detail below with reference to the accompanying drawings.
The following description of the embodiments of the present application is provided by way of specific examples, and other advantages and effects of the present application will be readily apparent to those skilled in the art from the disclosure herein. It is to be understood that the embodiments described are only a few embodiments of the present application and not all embodiments. The present application is capable of other and different embodiments and its several details are capable of modifications and/or changes in various respects, all without departing from the spirit of the present application. It is to be noted that the features in the following embodiments and examples may be combined with each other without conflict. All other embodiments obtained by a person of ordinary skill in the art based on the embodiments in the present application without making any creative effort belong to the protection scope of the present application.
It is noted that various aspects of the embodiments are described below within the scope of the appended claims. It should be apparent that the aspects described herein may be embodied in a wide variety of forms and that any specific structure and/or function described herein is merely illustrative. Based on the present application, one skilled in the art should appreciate that one aspect described herein may be implemented independently of any other aspects and that two or more of these aspects may be combined in various ways. For example, an apparatus may be implemented and/or a method practiced using any number and aspects set forth herein. Additionally, such an apparatus may be implemented and/or such a method may be practiced using other structure and/or functionality in addition to one or more of the aspects set forth herein.
It should be noted that the drawings provided in the following embodiments are only for illustrating the basic idea of the present application, and the drawings only show the components related to the present application rather than the number, shape and size of the components in actual implementation, and the type, amount and ratio of the components in actual implementation may be changed arbitrarily, and the layout of the components may be more complicated.
In addition, in the following description, specific details are provided to facilitate a thorough understanding of the examples. However, it will be understood by those skilled in the art that the invention may be practiced without these specific details.
In the optical non-contact measurement method, compared with the traditional interferometer with a lens combination, the optical fiber interferometer with the all-fiber structure has the advantages of compact and flexible structure, high sensitivity and strong environmental adaptability. Common optical fiber interferometers comprise an optical fiber Mach-Zehnder interferometer, an optical fiber Michelson interferometer and an optical fiber F-P interferometer, wherein the optical fiber Mach-Zehnder interferometer and the optical fiber Michelson interferometer have the problems of complex system structure and need of setting a reference arm in the application of surface topography measurement due to the structures of light splitting paths of the optical fiber Mach-Zehnder interferometer and the optical fiber Michelson interferometer.
Patent document CN107796423A discloses an optical fiber interferometer using micro lenses, which adds micro lenses to the output end of the optical fiber interferometer for coupling, and improves the light collection capability of the detection system and the spatial resolution of sample detection by means of the large numerical aperture of the micro lenses and the convergence effect on the light beams, however, the optical path splitting structure interferometer is adopted, the structure of the measuring head is complex, and the integration of the surface morphology detection system is not facilitated. Patent document CN112097680a discloses a surface topography test device and test method based on a multi-cavity FP interferometer, which uses a fiber circulator to form a multi-cavity fiber F-P interferometer, and can simultaneously test the topography of a surface to be tested, without scanning process, avoiding time required for scanning and mechanical vibration interference caused by scanning. In principle, the method of intensity demodulation is used in the patent, and the stability is poor compared with the spectrum demodulation; in the measurement scheme, a plurality of groups of optical fiber F-P interferometers are used for completely covering a certain area of the measured surface, and the method has the defects of narrow measurement range, high design requirement of an optical system and complex whole system. The displacement measurement principle of the F-P interferometer is that displacement change is calculated according to intensity signal change, and the interference of the F-P interferometer is large; a scanning mode is not adopted on the surface detection system, the requirement on the size of a detected piece is met, and the application range is narrow.
The optical fiber F-P interferometer is a common optical path structure interferometer, and the working principle of the optical fiber F-P interferometer is that the phase change of an F-P cavity interference field is changed by changing the cavity length of an F-P cavity. Due to the unique working principle and the common light path structure of the F-P interferometer, the optical fiber F-P interferometer applied to displacement measurement has the advantages of high sensitivity, strong stability and simple structure.
However, currently, the optical fiber F-P interferometer is generally applied to scenes such as one-dimensional displacement measurement, object micro-vibration measurement and the like, and there are only reports that the optical fiber F-P interferometer is applied to three-dimensional surface topography measurement, and meanwhile, the traditional intensity demodulation optical fiber F-P interferometer also has the problems of small measurement range and low stability.
Based on this, the embodiment of the present specification proposes a processing scheme: as shown in fig. 1, the surface topography of the object to be measured is measured by combining the fiber head array and the micro lens array with the three-dimensional displacement table, and a plurality of irradiation points on the surface of the object to be measured are measured at the same time, so that the measurement speed is increased.
The technical solutions provided by the embodiments of the present application are described below with reference to the accompanying drawings.
As shown in fig. 1 to 3, an embodiment of the present specification provides a surface topography measuring apparatus, including: the fiber F-P interferes with the stylus 104 and the three-dimensional displacement stage.
The optical fiber F-P interference measuring head 104 is composed of an optical fiber head array 201 and a micro lens array 202, and the object 105 to be measured is fixed on the three-dimensional displacement table.
The three-dimensional displacement stage in the present embodiment includes a first displacement stage 106, a second displacement stage 107, and a third displacement stage 203; the first displacement table 106 is fixedly connected with the second displacement table 107, the object to be measured is fixed on the first displacement table 106, and the fiber head array 201 and the micro-lens array 202 are fixed on the third displacement table 203; the first displacement table 106 and the second displacement table 107 control the object to be measured to perform two-dimensional motion in the first plane, and the third displacement table 203 controls the fiber head array and the micro-lens array to perform one-dimensional motion in the direction perpendicular to the first plane.
Specifically, after being transmitted to the optical fiber F-P interference measuring head 104, the light beam passes through the optical fiber head array 201 and the micro lens array 202, is emitted from the exit surface of the micro lens array 202, and is collimated and irradiated on the surface of the object 105 to be measured; and, the three-dimensional displacement table drives the object to be measured 105 to make three-dimensional motion so as to measure the surface topography of the object to be measured 105.
Optionally, when the three-dimensional displacement table drives the object 105 to be measured to perform three-dimensional motion, the height between the exit surface of the microlens and the surface of the object to be measured changes, so that the cavity length of an F-P cavity formed by the exit surface of the microlens and the surface of the object to be measured changes, the surface height of the object 105 to be measured can be obtained according to the cavity length change of the F-P cavity, and the surface topography measurement of the object 105 to be measured is completed.
In the embodiment of the description, the optical fiber head array 201, the micro lens array 202 and the three-dimensional displacement table are combined to measure the surface appearance of the object to be detected, so that the measurement range and the measurement speed of the product for detecting the surface appearance of the optical fiber F-P interferometer are improved, the cost is reduced, the detection speed and the detection range of the product for detecting the microscopic surface appearance are improved, and the application object range is expanded.
Further, as shown in fig. 2, the microlens array 202 is constituted by a plurality of microlens units side by side; the exit surface of each microlens unit and the corresponding reflection area on the surface of the object to be measured 105 form an F-P cavity; the fiber head array 201 is opposite to the incidence surface of the micro lens unit, the fiber head array 201 is composed of a plurality of fiber units, and the plurality of fiber units correspond to the plurality of micro lens units one by one.
Further, as shown in fig. 3, each optical fiber unit includes an optical fiber 301, a protective tube 302, and a round stage 303; the optical fiber 301 is welded with a small cylindrical surface of the circular truncated cone 303, and the protection tube 302 is welded with a large cylindrical surface of the circular truncated cone 303; the circular arc surface of the circular truncated cone 303 faces the incident surface of the microlens unit.
In the embodiment of the present specification, the light beam is emitted to the surface of the object 105 to be measured by collimating the exit surface of the microlens array.
The surface topography measuring apparatus in embodiments herein further comprises: a laser 101, a fiber combiner 102, a fiber circulator 103, a displacement table control upper computer 108, a spectrometer 109 and a computer 110.
The laser 101 is a broadband light source and is used for outputting laser; laser is divided into a plurality of light beams by an optical fiber beam combiner 102, the light beams are transmitted to an optical fiber F-P interference measuring head 104 after passing through an optical fiber circulator 103, the light beams are transmitted to the optical fiber F-P interference measuring head 104, are emitted from the emergent surface of a micro lens array 202, are collimated and irradiated onto the surface of an object 105 to be measured, are reflected back and forth between the surface of the object 105 to be measured and the emergent surface of the micro lens array 202, a multi-beam interference field is formed in a plurality of F-P cavities, and the reflected part of the multi-beam interference field is transmitted to a spectrometer 109 through the optical fiber circulator 103; the three-dimensional displacement table carries out displacement real-time detection through a displacement sensor and feeds displacement data back to the displacement table control upper computer 108 in real time, the displacement table control upper computer 108 controls the three-dimensional displacement table to carry out three-dimensional motion through the displacement data and a preset motion track and feeds motion data of the three-dimensional motion back to the computer 110; the computer 110 completes the surface topography measurement of the object 105 to be measured according to the motion data fed back by the displacement table control upper computer 108 and the spectrum data on the spectrometer 109.
In an alternative embodiment, as shown in fig. 1 to 3, an embodiment of the present disclosure provides a surface topography measuring apparatus, including: the device comprises a laser 101, an optical fiber beam combiner 102, an optical fiber circulator 103, an optical fiber F-P interference measuring head 104, an object to be measured 105, a one-dimensional displacement table 106, a one-dimensional displacement table 107, a displacement table control upper computer 108, a spectrometer 109 and a computer 110. The laser 101 is a broadband light source, and its output band is determined comprehensively according to the surface reflectivity of the object 105 to be measured and the spectral response range of the spectrometer 109. The object 105 to be measured is fixed on the one-dimensional displacement table 106, the one-dimensional displacement table 106 and the one-dimensional displacement table 107 are fixed, and no relative movement exists between the one-dimensional displacement table 106 and the one-dimensional displacement table 107. The one-dimensional displacement stage 203 is a component of the fiber F-P interference side head 104, and functions to fix the fiber head array 201 and the microlens array 202. The one-dimensional displacement table 106, the one-dimensional displacement table 107 and the one-dimensional displacement table 203 detect the displacement of the two-dimensional displacement table in real time through internally integrated high-precision displacement sensors such as grating rulers and the like, and feed displacement data back to the displacement table control upper computer 108 in real time. The displacement table control upper computer 108 controls the one-dimensional movement of the optical fiber F-P interference measuring head 104 in the z direction by controlling the one-dimensional displacement table 203 and controls the two-dimensional movement of the measured object 105 in the x and y planes by controlling the one-dimensional displacement table 106 and the one-dimensional displacement table 107 by combining the displacement data fed back by the one-dimensional displacement table 106, the one-dimensional displacement table 107 and the one-dimensional displacement table 203 with preset movement tracks in all directions. The one-dimensional displacement table 106 and the one-dimensional displacement table 107 respectively drive the object 105 to be measured to perform scanning motions in the y direction and the x direction. The computer 110 calculates the relative heights of the points on the surface of the object to be measured according to the displacement information data fed back by the displacement table control upper computer 108 and the spectrum data of the spectrometer 109.
The optical fiber F-P interference probe 104 includes an optical fiber head array 201, a micro lens array 202, and a one-dimensional displacement table 203. The fiber head array 201 and the micro lens array 202 form a laser collimation system, and the function of the laser collimation system is to enable laser emitted by the micro lens array 202 to be a test beam with good collimation. The exit surface of the microlens array 202 is a plane, and functions to form an F-P interference cavity, i.e., an F-P cavity, with the region of the surface of the object 105 to be measured illuminated by the light spot, where the object 105 to be measured and the object 105 to be measured are the same object in different modes. The fiber head array 201 and the micro lens array 202 are fixed to a one-dimensional displacement table 203. The one-dimensional displacement table 203 drives the fiber head array 201 and the micro lens array 202 to do z-direction one-dimensional motion under the control of the displacement table control upper computer 108, the motion range is the distance between two adjacent focusing light spots on the surface of the object 105 to be measured, and the distance can be calculated according to the specific parameters of the actual fiber head array 201 and the micro lens array 202 and the distance between the actual fiber head array 201 and the object 105 to be measured. In practical applications, there is no perfectly collimated outgoing beam with a divergence angle of 0 °, so the range of motion a of the one-dimensional motion stage 204 can be obtained according to equation (1):
A＝D-D 1 -2·l 1 ·θ+2·l 2 ·a·θ； (1)
wherein a represents the angular magnification of a single microlens unit in the microlens array; d represents the center-to-center spacing of adjacent microlens units; θ represents the numerical aperture of the fiber head unit; d 1 Represents the core diameter of the optical fiber; l 1 The distance between the micro-lens array and the end face of the optical fiber is small; l 2 Representing the distance between the microlens array and the surface of the object to be measured.
Further, the optical fiber head array 201 is composed of optical fiber head units, and each optical fiber head unit includes an optical fiber 301, a protection tube 302, and a circular truncated cone 303. The protective tube 302 and the circular truncated cone 303 are made of common optical materials and are connected into a whole in a fusion welding mode, and the specific material type is determined according to the material and the fusion welding process of the optical fiber 301. The optical fiber 301 is welded with the small cylindrical surface of the circular truncated cone 303, and the protection tube 302 is welded with the large cylindrical surface of the circular truncated cone 303. The measuring surface of the circular truncated cone 303 is frosted or blacked to reduce the influence of scattered light on the measuring result, and the inner diameter of the protection tube 302 is slightly larger than the diameter of the small cylindrical surface of the fused quartz circular truncated cone 303 to reduce the stress of the optical fiber at the welding point and protect the welding point of the optical fiber.
An embodiment of the present disclosure further provides a surface topography measurement method, which is applicable to the surface topography measurement apparatus described above, and includes:
laser emitted by a laser is divided into a plurality of light beams by an optical fiber beam combiner, the light beams are transmitted to an optical fiber F-P interference measuring head after passing through an optical fiber circulator, are emitted from an emergent surface of a micro-lens array, are collimated and irradiated onto the surface of an object to be measured, and are reflected back and forth between the surface of the object to be measured and the emergent surface of the micro-lens array, a multi-beam interference field is formed in a plurality of F-P cavities, the reflection part of the multi-beam interference field is transmitted to a spectrometer through the optical fiber circulator, and the emergent surface of each micro-lens unit in the micro-lens array and the reflection area on the surface of the corresponding object to be measured form the F-P cavity; the three-dimensional displacement table carries out displacement real-time detection through a displacement sensor and feeds displacement data back to a displacement table control upper computer in real time, the displacement table control upper computer controls the three-dimensional displacement table to carry out three-dimensional motion through the displacement data and a preset motion track and feeds motion data of the three-dimensional motion back to a computer; and the computer controls the motion data fed back by the upper computer and the spectrum data on the spectrometer according to the displacement table to finish the surface appearance measurement of the object to be measured.
Specifically, laser emitted by the laser 101 is divided into a plurality of light beams by the optical fiber combiner 102, the light beams are transmitted to the optical fiber F-P interference measuring head 104 through the optical fiber ring group 103, the light beams are emitted from the end face of the microlens array 202 in the optical fiber F-P interference measuring head 104, are collimated and irradiated on the surface 105 to be measured and are reflected back and forth on the surface 105 to be measured and the emergent face of the microlens array 202, and finally form a multi-beam interference field, the emergent face of each microlens unit in the microlens array 202 and the reflecting area of the corresponding surface to be measured form an F-P cavity, the reflecting end part of the multi-beam interference field is transmitted to the spectrometer 109 through the optical fiber ring group 103, the change amount of the cavity length of each F-P cavity is calculated according to the spectral change, and the relative height of each point on the surface of the object to be measured is obtained.
Wherein, three-dimensional displacement platform includes first displacement platform, second displacement platform and third displacement platform, includes: adjusting the first displacement table and the second displacement table to enable the micro-lens array to irradiate on an initial sampling point of the object to be detected, and adjusting the relative position of the optical fiber F-P interference measuring head and the object to be detected through the third displacement table to obtain a first distance between the optical fiber F-P interference measuring head and the object to be detected at the initial sampling point; the third displacement table is kept unchanged, the object to be measured is driven by the first displacement table to perform continuous one-dimensional motion in the second direction, the first cavity length data of the F-P cavity at each moment in the one-dimensional motion is calculated through the spectrum data in the one-dimensional motion process, and the second distance of each sampling point on the surface of the object to be measured in the second direction relative to the initial sampling point is obtained according to the first cavity length data and the first distance, wherein the second direction is the y direction in the graph 1; the third displacement table is kept unchanged, the object to be measured is driven by the second displacement table to perform continuous one-dimensional motion in the first direction, second cavity length data of the F-P cavity at each moment in the one-dimensional motion are calculated through spectrum data in the one-dimensional motion, and a third distance of each sampling point of the surface of the object to be measured in the first direction relative to the initial sampling point is obtained according to the second cavity length data and the first distance, wherein the first direction is the x direction in the graph 1; and finishing the surface topography measurement of the object to be measured according to the first distance, the second distance and the third distance.
And in the process that the object to be detected makes continuous one-dimensional motion in the second direction under the drive of the first displacement table, the cavity length of an F-P cavity formed by the surface of the object to be detected and the optical fiber F-P interference measuring head changes.
Specifically, any point on the object to be measured is selected as an initial sampling point, and the one-dimensional displacement stage 106 and the one-dimensional displacement stage 107 are adjusted so that the microlens array 202 irradiates on the initial sampling point. The relative position of the optical fiber F-P interference measuring head 104 and the object to be measured is adjusted through the one-dimensional displacement table 203, so that the feedback signal intensity is maximum, and a first distance H0 between the interference measuring head 104 and the object to be measured is obtained according to feedback of a high-precision displacement sensor integrated in the one-dimensional displacement table 203, such as a grating ruler and the like; the one-dimensional displacement table 203 keeps the original position unchanged, the object 105 to be measured does continuous one-dimensional motion in the y direction under the drive of the one-dimensional displacement table 106, at this time, the relative distance between each point on the surface of the object and the optical fiber F-P interference measuring head 104 changes, namely, the cavity length of the F-P cavity formed by the surface of the object to be measured and the corresponding point and the optical fiber F-P interference measuring head 104 changes, and the first cavity length data of the F-P cavity at each moment in the motion process is solved through spectrum change: h t1 、H t2 ……H tn Where t1 and t2 … … tn represent different times, H t1 、H t2 ……H tn And representing the cavity lengths at different moments, the height difference of each sampling point of the surface of the object to be measured in the y direction relative to the initial sampling point, namely a second distance: h t1 -H0、H t2 -H0……H tn -H0; completing the scanning of the y direction of the surface of the object to be detected; similarly, the one-dimensional displacement table 203 keeps the original position unchanged, the object 105 to be measured makes continuous one-dimensional motion in the x direction under the drive of the one-dimensional displacement table 107, a third distance of each sampling point of the surface of the object to be measured in the x direction relative to the initial sampling point is obtained, and the scanning of the surface of the object to be measured in the x direction is completed; the computer 110 calculates the first distance, the second distance and the third distanceAnd after the relative height difference of each sampling point on the surface of the object to be measured, the recovery and measurement of the surface appearance of the object to be measured are completed by combining the distance H0 between the initial sampling point and the interference measuring head 104.
The embodiment of the specification adopts a measuring head distance measuring scheme of spectrum demodulation, improves the distance measuring precision and the environmental stability of an optical fiber F-P interference surface morphology detection product, improves the detection precision of a microscopic surface morphology detection product, and enlarges the application scene range of the microscopic surface morphology detection product.
The embodiment of the present specification further provides an object surface height calculation method, which is applied to the surface topography measurement method, and includes:
step 1: and obtaining an interference pattern according to the initial reflection spectrum of the F-P cavity, tracking and recording the central wavelength of a resonance peak in the interference pattern, wherein the exit surface of each micro lens unit in the micro lens array and the corresponding reflection area on the surface of the object to be detected form the F-P cavity.
Step 2: and calibrating the cavity length variation of the F-P cavity and the wavelength variation of the center wavelength of the resonance peak to obtain the corresponding relation between the cavity length variation and the wavelength variation.
And step 3: and obtaining the cavity length variation of the F-P cavity according to the wavelength variation and the corresponding relation in the measurement process of the object to be measured.
And 4, step 4: and obtaining the surface height of the object to be measured according to the cavity length variation.
Specifically, an initial reflection spectrum of each F-P interference cavity is first acquired. The interference spectral intensity of the reflected light output by each F-P cavity can be represented by equation (2):
wherein j =1,2,3, … … n, I j Representing the intensity of the interference field; a. The j Representing the reflected light intensity of the exit surface of the single microlens unit; b is j Representing the reflection light intensity of the irradiation surface of the object to be measured; phi j Represents the phase of the F-P cavity; n is air Represents the refractive index of air; l is j Representing a single microlens elementThe distance from the emergent surface to the irradiation surface of the object to be measured; and lambda is the central wavelength of the vibration peak, when the phase meets the condition of the interferometer, a stable interference spectrum is formed on the spectrometer, a plurality of resonance peaks are formed, and the central wavelength of a certain resonance peak is tracked and recorded.
Then: and calibrating the cavity length variation of the F-P cavity and the wavelength variation of the central wavelength of the tracked resonance peak. In the structure of fig. 1, the object 105 to be measured is replaced with a planar optical element such as a mirror, a parallel plate, or the like, whose surface roughness and surface reflectivity are similar to those of the object 105 to be measured. The optical fiber F-P interference measuring head 104 emits test light to irradiate on the planar optical element, the optical fiber F-P interference measuring head 104 is moved along the z direction by using the third displacement table 203, when the cavity length of the F-P cavity is changed, the central wavelength of a tracked resonance peak can be changed, and the wavelength drift amount and the displacement amount meet the formula (3).
Wherein the content of the first and second substances,
represents the F-P cavity phase; n represents the refractive index of air; l represents the initial length of the F-P cavity, and Δ L represents the change of the length of the F-P cavity due to the movement of the third displacement table 203; λ represents the initial center wavelength of the resonance peak; Δ λ represents the amount of shift in the center wavelength of the resonance peak due to the change in F-P cavity length.
Specifically, the cavity length of an F-P cavity formed by the optical fiber F-P interference measuring head 104 and the standard plane optical element in the moving process of the third displacement table 203 along the z direction, that is, the distance between the optical fiber F-P interference measuring head 104 and the standard plane optical element, is fed back and output in real time by a high-precision displacement sensor, such as a grating ruler, integrated inside the third displacement table 203. And establishing a one-to-one correspondence relationship between the central wavelength drift amount of the tracked resonance peak and the cavity length change amount of the F-P cavity by combining the central wavelength drift amount of the tracked resonance peak fed back by the spectrometer 109, wherein the one-to-one correspondence relationship can be a mapping table or a mapping formula and the like.
And then: and tracking the central wavelength change of a certain peak value of the reflection interference spectrum in the measurement, and contrasting or calculating according to the corresponding relation determined by the calibration, such as a mapping table or a mapping formula and the like to obtain the cavity length change quantity of the corresponding F-P cavity.
And finally, obtaining the surface height of the object to be measured according to the cavity length variation.
In the embodiment of the specification, the one-dimensional displacement measurement is completed by tracking the variation of a certain peak wavelength of the reflection spectrum of the interference field, and compared with an intensity demodulation optical fiber F-P interferometer in the prior art, the sensitivity is higher and the anti-interference capability is stronger.
In the embodiment of the specification, the F-P interference measuring head is formed by coupling an optical fiber head array and a micro-lens array, and simultaneously measures a plurality of irradiation points on the surface of an object to be measured, so that the measuring speed is improved.
In the embodiment of the specification, non-contact measurement is adopted to ensure that the surface of the object to be measured is not damaged.
The embodiments in the present specification are described in a progressive manner, and the same and similar parts among the embodiments can be referred to each other, and each embodiment focuses on the differences from the other embodiments. In particular, for the product embodiments described later, since they correspond to the method, the description is simple, and the relevant points can be referred to the partial description of the system embodiments.
The above description is only for the specific embodiments of the present application, but the scope of the present application is not limited thereto, and any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope of the present application should be covered within the scope of the present application. Therefore, the protection scope of the present application shall be subject to the protection scope of the claims.
Claims (10)
1. A surface topography measurement apparatus, comprising: the optical fiber F-P interference measuring head and the three-dimensional displacement platform are arranged on the optical fiber F-P interference measuring head;
the optical fiber F-P interference measuring head consists of an optical fiber head array and a micro lens array, and an object to be measured is fixed on the three-dimensional displacement table;
transmitting light beams to the optical fiber F-P interference measuring head, transmitting the light beams from the emergent surface of the micro lens array after passing through the optical fiber head array and the micro lens array, and collimating and irradiating the light beams to the surface of the object to be measured;
the three-dimensional displacement table drives the object to be measured to do three-dimensional motion so as to measure the surface appearance of the object to be measured.
2. The surface topography measuring apparatus according to claim 1, wherein said microlens array is constituted by a plurality of microlens units side by side;
and the emergent surface of each micro-lens unit and the corresponding reflection area on the surface of the object to be measured form an F-P cavity.
3. The surface topography measuring device according to claim 2, wherein said fiber head array is opposed to an incident surface of said microlens unit, said fiber head array being constituted by a plurality of fiber units, a plurality of said fiber units corresponding to a plurality of said microlens units one to one.
4. The surface topography measuring device according to claim 3, wherein each of said optical fiber units comprises an optical fiber, a protective tube and a circular truncated cone;
the optical fiber is welded with the small cylindrical surface of the circular truncated cone, and the protection tube is welded with the large cylindrical surface of the circular truncated cone;
the circular arc surface of the circular truncated cone is opposite to the incident surface of the micro lens unit.
5. The surface topography measuring apparatus according to claim 1, wherein said three-dimensional displacement stage comprises a first displacement stage, a second displacement stage and a third displacement stage;
the first displacement table is fixedly connected with the second displacement table, the object to be detected is fixed on the first displacement table, and the optical fiber head array and the micro-lens array are fixed on the third displacement table;
the first displacement table and the second displacement table control the object to be measured to perform two-dimensional motion in a first plane, and the third displacement table controls the optical fiber head array and the micro-lens array to perform one-dimensional motion in a direction perpendicular to the first plane.
6. The surface topography measurement device according to any of claims 1 to 5, further comprising: the device comprises a laser, an optical fiber beam combiner, an optical fiber circulator, a displacement table control upper computer, a spectrometer and a computer;
the laser is a broadband light source and is used for outputting laser;
the laser is divided into a plurality of light beams by the optical fiber beam combiner, the light beams are transmitted to the optical fiber F-P interference measuring head after passing through the optical fiber circulator, the light beams are transmitted to the optical fiber F-P interference measuring head, are emitted from the emergent surface of the micro lens array and are collimated and irradiated onto the surface of the object to be measured, and are reflected back and forth between the surface of the object to be measured and the emergent surface of the micro lens array, a multi-beam interference field is formed in the F-P cavities, and the reflected part of the multi-beam interference field is transmitted to the spectrometer through the optical fiber circulator;
the three-dimensional displacement table carries out displacement real-time detection through a displacement sensor and feeds displacement data back to the displacement table control upper computer in real time, the displacement table control upper computer controls the three-dimensional displacement table to carry out three-dimensional motion through the displacement data and a preset motion track and feeds motion data of the three-dimensional motion back to the computer;
and the computer completes the surface appearance measurement of the object to be measured according to the motion data fed back by the displacement table control upper computer and the spectrum data on the spectrometer.
7. A surface topography measuring method, which is applied to the surface topography measuring apparatus according to any one of claims 1 to 6, comprising:
laser emitted by a laser is divided into a plurality of light beams by an optical fiber beam combiner, the light beams are transmitted to an optical fiber F-P interference measuring head after passing through an optical fiber circulator, are emitted from an emergent surface of a micro lens array, and are collimated and irradiated onto the surface of an object to be measured, and are reflected back and forth between the surface of the object to be measured and the emergent surface of the micro lens array, a multi-beam interference field is formed in a plurality of F-P cavities, the reflection part of the multi-beam interference field is transmitted to the spectrometer through the optical fiber circulator, and the emergent surface of each micro lens unit in the micro lens array and the reflection area on the corresponding surface of the object to be measured form the F-P cavity;
the three-dimensional displacement table carries out displacement real-time detection through a displacement sensor and feeds displacement data back to a displacement table control upper computer in real time, the displacement table control upper computer controls the three-dimensional displacement table to carry out three-dimensional motion through the displacement data and a preset motion track and feeds motion data of the three-dimensional motion back to a computer;
and the computer completes the surface appearance measurement of the object to be measured according to the motion data fed back by the displacement table control upper computer and the spectrum data on the spectrometer.
8. The method of claim 7, wherein the three-dimensional displacement stage comprises a first displacement stage, a second displacement stage, and a third displacement stage, comprising:
adjusting the first displacement table and the second displacement table to enable the micro lens array to irradiate on an initial sampling point of the object to be detected, and adjusting the relative position of the optical fiber F-P interference measuring head and the object to be detected through the third displacement table to obtain a first distance between the optical fiber F-P interference measuring head and the object to be detected at the initial sampling point;
the third displacement table is kept unchanged, the object to be detected is driven by the first displacement table to make continuous one-dimensional motion in a second direction, first cavity length data of an F-P cavity at each moment in the one-dimensional motion are calculated through the spectral data in the one-dimensional motion process, and a second distance of each sampling point on the surface of the object to be detected in the second direction relative to the initial sampling point is obtained according to the first cavity length data and the first distance;
the third displacement table is kept unchanged, the object to be detected makes continuous one-dimensional motion in the first direction under the drive of the second displacement table, second cavity length data of an F-P cavity at each moment in the one-dimensional motion are calculated through the spectrum data in the one-dimensional motion, and a third distance of each sampling point of the surface of the object to be detected in the first direction relative to the initial sampling point is obtained according to the second cavity length data and the first distance;
and finishing the surface topography measurement of the object to be measured according to the first distance, the second distance and the third distance.
9. The method according to claim 8, wherein a cavity length of the F-P cavity formed by the surface of the object to be measured and the optical fiber F-P interference probe changes during the continuous one-dimensional movement of the object to be measured in the second direction driven by the first displacement stage and the continuous one-dimensional movement of the object to be measured in the first direction driven by the second displacement stage.
10. A method for calculating the height of the surface of an object, which is applied to the surface topography measuring method according to any one of claims 7 to 9, comprising:
step 1: obtaining an interference pattern according to the initial reflection spectrum of the F-P cavity, tracking and recording the central wavelength of a resonance peak in the interference pattern, wherein the exit surface of each micro lens unit in the micro lens array and the corresponding reflection area on the surface of the object to be detected form the F-P cavity;
step 2: calibrating the cavity length variation of the F-P cavity and the wavelength variation of the center wavelength of the resonance peak to obtain the corresponding relation between the cavity length variation and the wavelength variation;
and step 3: obtaining the cavity length variation of the F-P cavity according to the wavelength variation and the corresponding relation in the process of measuring the object to be measured;
and 4, step 4: and obtaining the surface height of the object to be measured according to the cavity length variation.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202211020203.8A CN115371587A (en) | 2022-08-24 | 2022-08-24 | Surface topography measuring device and method and object surface height calculating method |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202211020203.8A CN115371587A (en) | 2022-08-24 | 2022-08-24 | Surface topography measuring device and method and object surface height calculating method |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN115371587A true CN115371587A (en) | 2022-11-22 |
Family
ID=84068736
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202211020203.8A Pending CN115371587A (en) | 2022-08-24 | 2022-08-24 | Surface topography measuring device and method and object surface height calculating method |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN115371587A (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN116222415A (en) * | 2022-12-06 | 2023-06-06 | 安徽至博光电科技股份有限公司 | Surface morphology measuring device and method based on single wavelength-double FP cavity |
| CN116295108A (en) * | 2023-05-25 | 2023-06-23 | 中国科学院长春光学精密机械与物理研究所 | Matrix type contour measurement method and device |
-
2022
- 2022-08-24 CN CN202211020203.8A patent/CN115371587A/en active Pending
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN116222415A (en) * | 2022-12-06 | 2023-06-06 | 安徽至博光电科技股份有限公司 | Surface morphology measuring device and method based on single wavelength-double FP cavity |
| CN116222415B (en) * | 2022-12-06 | 2023-11-28 | 安徽至博光电科技股份有限公司 | Surface morphology measuring device and method based on single wavelength-double FP cavity |
| CN116295108A (en) * | 2023-05-25 | 2023-06-23 | 中国科学院长春光学精密机械与物理研究所 | Matrix type contour measurement method and device |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CN111220090A (en) | Line focusing differential color confocal three-dimensional surface topography measuring system and method | |
| CN115371587A (en) | Surface topography measuring device and method and object surface height calculating method | |
| US6882433B2 (en) | Interferometer system of compact configuration | |
| Berger et al. | Non-contact metrology of aspheric surfaces based on MWLI technology | |
| CN104913732B (en) | The normal tracking mode non-spherical measuring method and system interfered based on recombination laser | |
| CN110514142B (en) | Surface shape detection device and surface shape detection method | |
| CN112648926B (en) | Line-focusing color confocal three-dimensional surface height measuring device and method | |
| CN101105390A (en) | Synthetic wave interference nano surface tri-dimensional on-line measuring system and method | |
| CN104913733B (en) | The normal tracking mode non-spherical measuring method and system interfered based on multiwavelength laser | |
| Kuang et al. | A four-degree-of-freedom laser measurement system (FDMS) using a single-mode fiber-coupled laser module | |
| CN211876977U (en) | Line focusing differential color confocal three-dimensional surface topography measuring system | |
| US11073370B2 (en) | OCT measurement device with back-reflection | |
| US4538911A (en) | Three-dimensional interferometric length-measuring apparatus | |
| JP7182306B2 (en) | Position measurement of objects in space | |
| US20150077759A1 (en) | Compact, Slope Sensitive Optical Probe | |
| US6614534B1 (en) | Method and apparatus for combined measurement of surface non-uniformity index of refraction variation and thickness variation | |
| CN112710251B (en) | Multi-mode optical online measuring device and measuring method | |
| CN205581024U (en) | Optical element surface defect detecting device of transmission type synthetic aperture digital holographic art | |
| JP5704150B2 (en) | White interference device and position and displacement measuring method of white interference device | |
| CN114144635A (en) | Device and method for measuring the height profile of an object | |
| Marcus | Fiber optic interferometry for industrial process monitoring and control applications | |
| JP2541197Y2 (en) | Interference shape measuring instrument | |
| JPH01235807A (en) | Depth measuring instrument | |
| US20180283845A1 (en) | Wavelength modulatable interferometer | |
| CN205562427U (en) | Optical element surface defect detecting device of reflection -type synthetic aperture digital holographic art |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination |