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CN-121677608-B - Super-surface-based spectrum interference surface morphology measurement method and device

CN121677608BCN 121677608 BCN121677608 BCN 121677608BCN-121677608-B

Abstract

The application relates to the technical field of surface topography measurement and discloses a method and a device for measuring spectral interference surface topography based on a super surface. The device comprises a spectrometer, a white light source, an optical fiber, a focusing super surface and a dispersion super surface which are arranged in parallel and aligned, wherein spherical thin lenses and micro-nano structures are respectively arranged on two sides of the focusing super surface, a reflecting metal film is arranged in the middle of two sides of the focusing super surface, a semi-transparent semi-reflective film and a micro-nano structure are respectively arranged on two sides of the dispersion super surface, the focusing super surface is used for converging parallel incident light, one part of light is used as reference light and is reflected and focused on a reflecting coating by the semi-transparent semi-reflective film, the other part of light is used as measuring light and is transmitted through the semi-transparent semi-reflective film, the dispersion super surface is used for axially dispersing the light transmitted through the semi-transparent semi-reflective film, and monochromatic light focused on a surface to be measured returns along an optical path and interferes with the reference light to generate confocal signals or interference signals so as to calculate the shape information of the surface to be measured. By adopting the device, high-precision surface morphology measurement can be realized in a narrow space.

Inventors

  • LU WENLONG
  • CAO ZHICHEN
  • CHANG SUPING

Assignees

  • 华中科技大学

Dates

Publication Date
20260508
Application Date
20260210

Claims (10)

  1. 1. The spectral interference surface morphology measuring device based on the super surface is characterized by comprising a spectrometer, a white light source, an optical fiber and a super surface mirror group, wherein the super surface mirror group comprises a collimating mirror, a focusing super surface and a dispersion super surface which are arranged in parallel and aligned, a set distance exists between the dispersion super surface and the focusing super surface, the distance is equal to half of the working focal length of the focusing super surface; The collimating lens is used for collimating the divergent light emitted by the optical fiber light outlet into parallel incident light, and the position of the collimating lens is determined by the numerical aperture of the optical fiber light outlet and the caliber of the optical fiber light outlet; the focusing super surface is used for converging parallel incident light, one part of the light is used as reference light, the reference light is reflected and focused on the reflecting coating by the semi-transparent semi-reflecting film, and the other part of the light is used as measuring light and penetrates through the semi-transparent semi-reflecting film; The dispersion super surface is used for axially dispersing the light transmitted through the semi-transparent semi-reflective film, and monochromatic light focused on the surface to be measured returns to the super surface mirror group along a light path and interferes with reference light to generate confocal signals or interference signals; The spectrometer is used for receiving the confocal signals or the interference signals, and the confocal signals or the interference signals are used for calculating the morphology information of the surface to be measured.
  2. 2. The measuring device according to claim 1, wherein the material selection of the spherical thin lens in the focusing super surface is determined by the working focal length of the focusing super surface, the radius of curvature of the spherical thin lens obtained by preliminary calculation, the center wavelength of the working band of the incident light, and the refractive index of the spherical thin lens material corresponding to the center wavelength.
  3. 3. The measuring device of claim 2, wherein the working focal length F when focusing the super surface is greater than When the refractive index of the spherical thin lens is smaller than the preset refractive index threshold and the chromatic dispersion is smaller than the preset chromatic dispersion threshold, the working focal length F of the focusing super-surface is not larger than When the refractive index of the spherical thin lens is not less than the set refractive index threshold value and the dispersion is not less than the set dispersion threshold value, wherein, The calculation formula of the spherical thin lens curvature radius obtained by preliminary calculation is as follows: ; indicating the center wavelength of the operating band of incident light, Representing the refractive index of the spherical thin lens material corresponding to the center wavelength, Representing the derivative of the refractive index of the spherical thin lens material with respect to the wavelength function, The function value of the derivative of the refractive index of the spherical thin lens material with the wavelength function at the center wavelength is represented.
  4. 4. The measurement device of claim 1, wherein the layout of micro-nano structures in the focusing supersurface is determined by: , Wherein, the Representing focused super-surface coordinates The phase of the micro-nano structure is positioned, Indicating the working focal length of the focusing super-surface, Indicating the wavelength of the incident light, And Respectively represent the horizontal coordinate value and the vertical coordinate value of the position of the micro-nano structure.
  5. 5. The measurement device of claim 4, wherein the focal super-surface coordinates The cross-sectional area of the micro-nanostructure is determined by: , Wherein, the Representing focused super-surface coordinates The cross-sectional area of the micro-nano structure, Indicating the location of the micro-nano structure the cross-sectional area of the periodic space, Representing the refractive index of the material of the micro-nano structure, Indicating the refractive index of the medium in which the focusing supersurface is located, Is the height of the micro-nano structure.
  6. 6. The measurement device of claim 1, wherein the layout of micro-nano structures in the dispersive subsurface is determined by: , Wherein, the Representing dispersive subsurface coordinates The phase of the micro-nano structure is positioned, And Representing the first of the wavelength sequences The number of wavelength sequences is N, the number of wavelength data and their corresponding focal lengths.
  7. 7. The measurement device of claim 6, wherein the dispersive super-surface coordinates The cross-sectional area of the micro-nanostructure is determined by: , Wherein, the Representing dispersive subsurface coordinates The cross-sectional area of the micro-nano structure, Indicating the location of the micro-nano structure the cross-sectional area of the periodic space, Representing the refractive index of the material of the micro-nano structure, Representing the refractive index of the medium in which the dispersive subsurface is located, Is the height of the micro-nano structure.
  8. 8. A method for measuring a super-surface based spectral interference surface topography, applied to the super-surface based spectral interference surface topography measuring device according to any one of claims 1 to 7, the measuring method comprising: Acquiring spectrometer signal data received by a spectrometer; and obtaining the morphology information of the surface to be measured according to the spectrometer signal data.
  9. 9. The method of measuring according to claim 8, wherein obtaining topography information of the surface to be measured from the spectrometer signal data comprises: When the surface to be measured is in the dispersion range, the spectrometer signal data comprise confocal signals, wavelength sequence data and light intensity sequence data, and the morphology information of the surface to be measured is obtained according to the wavelength sequence data, the light intensity sequence data and the wavelength-focal length corresponding relation.
  10. 10. The method of measuring according to claim 8, wherein obtaining topography information of the surface to be measured from the spectrometer signal data comprises: When the surface to be measured is in the interferometry range, the spectrometer signal data comprise interference signals, and the morphology information of the surface to be measured is obtained according to the interference signals.

Description

Super-surface-based spectrum interference surface morphology measurement method and device Technical Field The application relates to the technical field of micro-nano optics and high-precision surface morphology measurement, in particular to a super-surface-based spectral interference surface morphology measurement method and device. Background The surface morphology measurement plays an important role in the fields of high-end manufacturing and strategy such as aerospace, precise instruments, nuclear fusion and the like. The existing surface morphology measuring method mainly uses a contact type surface profile measuring instrument, but the contact type measuring method is low in efficiency and is easy to damage the surface of a sample, and is difficult to adapt to the requirements of mass nondestructive detection. The non-contact white light interferometer has the problems of large equipment volume, difficult measurement in a narrow space environment and the like, although the efficiency is high, and the surface of a sample is not damaged. At present, a measurement mode combining spectral confocal and white light interference is gradually developed, and the measurement method combines a wide range of the spectral confocal and high axial resolution of interference measurement, so that high-precision measurement can be carried out on complex surface morphology. Compared with a white light interferometer, the volume of the interferometer is slightly reduced, but due to factors such as traditional optical lens materials and aberration optimization, the optical path system is complex in structure, and high-precision measurement of the surface morphology in narrow spaces such as blisks, micropores and gaps is still difficult to realize. Disclosure of Invention In order to solve the problem of low measurement precision of the surface morphology in a narrow space, the invention provides a super-surface-based spectral interference surface morphology measurement method and device, which can realize non-contact high-precision spectral interference surface morphology measurement in the narrow space. To achieve the above object, according to a first aspect of the present invention, there is provided a super-surface-based spectral interferometry surface topography measuring apparatus comprising: The device comprises a spectrometer, a white light source, an optical fiber and a super-surface lens group, wherein the super-surface lens group comprises a collimating lens, a focusing super-surface and a dispersing super-surface which are arranged in parallel and aligned, wherein a set distance exists between the dispersing super-surface and the focusing super-surface, and the distance is equal to half of the working focal length of the focusing super-surface; The collimating mirror is used for collimating the divergent light emitted by the optical fiber light outlet into parallel incident light, and the position of the collimating mirror is determined by the numerical aperture of the optical fiber light outlet and the caliber of the optical fiber light outlet; The focusing super surface is used for converging parallel incident light, one part of the light is used as reference light, the reference light is reflected and focused on the reflecting coating by the semi-transparent semi-reflecting film, and the other part of the light is used as measuring light and penetrates through the semi-transparent semi-reflecting film; The dispersive super-surface is used for axially dispersing the light transmitted through the semi-transparent semi-reflective film, and monochromatic light focused on the surface to be measured returns to the super-surface mirror group along the light path and interferes with the reference light to generate a confocal signal or an interference signal; The spectrometer is used for receiving confocal signals or interference signals, and the confocal signals or interference signals are used for calculating the morphology information of the surface to be measured. Further, the material selection of the spherical thin lens in the focusing super surface is determined by the working focal length of the focusing super surface, the radius of curvature of the spherical thin lens obtained through preliminary calculation, the central wavelength of the incident light working wave band and the refractive index of the spherical thin lens material corresponding to the central wavelength. Further, when the working focal length F of the focusing super-surface is greater thanWhen the refractive index of the spherical thin lens is smaller than the preset refractive index threshold and the chromatic dispersion is smaller than the preset chromatic dispersion threshold, the working focal length F of the focusing super-surface is not larger thanWhen the refractive index of the spherical thin lens is not less than the set refractive index threshold value and the dispersion is not less than the set dispersion threshold value, wherei