Phase-shift algorithm for white-light interferometry insensitive to linear errors in phase shift
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White-light interference has changes in fringe contrast. When phase-shift techniques are applied to white-light interference, the phase-shift algorithm which can extract the phase accurately under the contrast changes is required. There is often another requirement that the phase shift between frames should not be restricted to π/2. Computer simulations show that the well-known algorithms have non-negligible errors under both requirements. To find an algorithm which will satisfy the requirements, I extract individual terms (Ij ∓ Ik) in an algorithmic equation by considering symmetry of light intensity against phase, where Ij is light intensity just after the j-th phase shift. Using computer simulations, I search for appropriate coefficients by which the terms are multiplied in the equation, finally finding an algorithm which satisfies both the requirements with the phase shift used.
Key wordsphase shift algorithm white-light interferometer fringe contrast error estimation computer simulation
- 4).J. E. Greivenkamp and J. H. Bruning: in Optical Shop Testing, ed. D. Malacara (Wiley, New York, 1992) 2nd ed., p. 524.Google Scholar
- 5).J. E. Greivenkamp and J. H. Bruning: in Optical Shop Testing, ed. D. Malacara (Wiley, New York, 1992) 2nd ed., p. 510.Google Scholar