Optics and Precision Engineering, Volume. 24, Issue 12, 3033(2016)
Filter calculation based on wavefront figures
To improve the measuring accuracy of optical interferometry, the filtering methods to eliminate the noise in interference fringe patterns were researched. The results of different filtering methods were discussed in different wavefronts and different noises of the interferometer. By taking the effects of interferometric noise on fringe patterns and different wavefronts into account, four kinds of fringe patterns for defocus, astigmatism, coma, spherical aberration were established based on zernike polynomials by matlab simulation. The differences of PV and GRMS values before and after filtering were calculated for different wavefronts. The results on four kinds of wavefronts for defocus, astigmatism, coma, spherical aberration show that under the same kind of noise and filtering, the PV difference of the spherical aberration is largest, up to 0.11λ, which shows a poor filtering effect as compared with the 0.08λ from other wavefront differences under the multiplicative noise. Furthermore, the PV difference of the astigmatism wavefront is smallest, and it is down to 0.05λ excepting median filtering in the multiplicative noise, showing a better filter effect. Moreover, the result of coma wavefront filtering is slightly better than that of the defocus wavefront filtering. For the filter methods, low-pass filters offer high-stability and the differences of the PV is from 0.01λ to 0.04λ, showing a better filtering effect.
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XIA Zhi-lin, ZENG Xiang, LIU Shi-jie, ZHOU You, ZHANG Zhi-gang. Filter calculation based on wavefront figures[J]. Optics and Precision Engineering, 2016, 24(12): 3033
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Received: Oct. 13, 2016
Accepted: --
Published Online: Jan. 23, 2017
The Author Email: Zhi-lin XIA (xiazhilin@whut.edu.cn)