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Development of a method for flat surface measurement of quasi-flat-bottomed plates using triple bonding

Zofia Sunderland

Abstract

This dissertation is devoted to flatness measurments of quasi-parallel plates taking advantage of three-beam interference. Method of analysis of the registered three-beam interferograms resulting in determination front and back surface flatness and optical thickness variation assuming homogeneous distribution of refractive index of the element under test is proposed. Processing paths using a single three-beam interferogram or a set of (at least two) three-beam interferograms with mutual phase shift is developed. The first case may be applied to images registered in Twyman-Green interferometer, the second case also in the Fizeau system. In both cases determination of plate parameters may be realized without interference into the optomechanical setup or the plate. Firstly, each of the proposed processing paths eliminates a fringe set Ifb from a three-beam interferogram. The set Ifb results from interference of the beams reflected from the tested element surfaces. It leads to intensity distribution containing sum of two fringe families coding plate front and back surface topography, which is further processed. In case of wedge plates, for which number of fringes in the Ifb map is greater than 5, furher processing relies on separating the fringe sets with the use of single-frame algorithms for interferogram analysis, for example two-dimensional continuous wavelet transform or Hilbert-Huang transform. Also, the Fourier transform,Wigner-Hough pseudotransform and phase-shifting digital moiré method was tested. In case of parallel plates more complex, multi-stage processing is conducted. Finally the methods lead to to the same results, i.e. to information on plate front surface shape and other plate parameters. There are a few ways to carry out the elimination of the fringe set Ifb from a three-beam interferogram: in the Twyman-Green interferometer by registration of the Ifb interferogram while the reference beam is blocked and its subtraction from the three-beam interferogram, and in the Fizeau setup by manipulating the reference beam intensity or subtracting two phase-shifted three-beam interferograms. All operations are described by formulas derived in this work. Accuracy of the methods was estimated using both computer-generated and experimental images. The accuracy of obtained phase maps was compared with reference methods.
Record ID
WUT8896346f828643a3a7a3362aecc6e6b5
Diploma type
Doctor of Philosophy
Author
Title in Polish
Opracowanie metody pomiaru płaskości powierzchni płytek Quasi-płaskorównoległych z wykorzystaniem interferencji trójwiązkowej
Title in English
Development of a method for flat surface measurement of quasi-flat-bottomed plates using triple bonding
Language
(pl) Polish
Certifying Unit
Faculty of Mechatronics (FM)
Discipline
mechanical engineering / (technology domain) / (technological sciences)
Status
Finished
Defense Date
08-02-2017
Title date
22-02-2017
Supervisor
Internal reviewers
Wacław Urbańczyk Wacław Urbańczyk,, Author's external affiliation: Wroclaw University of Science and Technology
External reviewers
Jan K. Jabczyński Jan K. Jabczyński,, Author's external affiliation: Wojskowa Akademia Techniczna im. Jarosława Dąbrowskiego
Pages
121
Keywords in English
three-beam interference
Abstract in English
This dissertation is devoted to flatness measurments of quasi-parallel plates taking advantage of three-beam interference. Method of analysis of the registered three-beam interferograms resulting in determination front and back surface flatness and optical thickness variation assuming homogeneous distribution of refractive index of the element under test is proposed. Processing paths using a single three-beam interferogram or a set of (at least two) three-beam interferograms with mutual phase shift is developed. The first case may be applied to images registered in Twyman-Green interferometer, the second case also in the Fizeau system. In both cases determination of plate parameters may be realized without interference into the optomechanical setup or the plate. Firstly, each of the proposed processing paths eliminates a fringe set Ifb from a three-beam interferogram. The set Ifb results from interference of the beams reflected from the tested element surfaces. It leads to intensity distribution containing sum of two fringe families coding plate front and back surface topography, which is further processed. In case of wedge plates, for which number of fringes in the Ifb map is greater than 5, furher processing relies on separating the fringe sets with the use of single-frame algorithms for interferogram analysis, for example two-dimensional continuous wavelet transform or Hilbert-Huang transform. Also, the Fourier transform,Wigner-Hough pseudotransform and phase-shifting digital moiré method was tested. In case of parallel plates more complex, multi-stage processing is conducted. Finally the methods lead to to the same results, i.e. to information on plate front surface shape and other plate parameters. There are a few ways to carry out the elimination of the fringe set Ifb from a three-beam interferogram: in the Twyman-Green interferometer by registration of the Ifb interferogram while the reference beam is blocked and its subtraction from the three-beam interferogram, and in the Fizeau setup by manipulating the reference beam intensity or subtracting two phase-shifted three-beam interferograms. All operations are described by formulas derived in this work. Accuracy of the methods was estimated using both computer-generated and experimental images. The accuracy of obtained phase maps was compared with reference methods.
Thesis file
  • File: 1
    rozprawa_doktorska_Zofia_Sunderland.pdf
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Uniform Resource Identifier
https://repo.pw.edu.pl/info/phd/WUT8896346f828643a3a7a3362aecc6e6b5/
URN
urn:pw-repo:WUT8896346f828643a3a7a3362aecc6e6b5

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