Similar articles

Abstract: In this study, a displacement measurement method based on digital moiré; fringe is described and experimentally demonstrated. The method is formed by only one grating with a constant pitch. First, the magnified grating image is received by an imaging array and is sent to a computer. Then, the digital moiré; fringes are generated by overlaying the grating image with its mirrored one. Finally, a specifically designed algorithm is used to obtain the fringes’ phase difference before and after movement and calculate the displacement. This method has the effects of amplifying displacement and averaging the grating lines error, the same as the traditional moiré technique using two pieces of gratings. At the same time, the proposed system is much easier to assemble and the measurement resolution can be set more flexibly. One displacement measuring system based on this method was built up. Experiment results show that its measurement errors are less than 0.3 µm and less than 0.12 µm at the resolutions of 0.1 µm and 0.03 µm, respectively.

The authors present a well-known digital Moiré fringe method, which the authors applied like a displacement sensor and claim easier to assemble and more flexible to set the resolution displacement measuring system using a single grating. Because this method does not need complex grating interference system, it has the advantage of being easy to operate. The proposal is presented in a generally clear manner. Then the author shows the displacement calculation and its resolutions. Finally some experiments and quality of the Moiré fringes are presented.

一种用于位移传感器的数字莫尔方法

[1]Chen, X.X., Chang, C.C., 2015. A digital sampling moiré method for two-dimensional displacement measurement. SPIE, 9435:943523.

[2]Cheng, F., Fan, K.C., 2011. Linear diffraction grating interferometer with high alignment tolerance and high accuracy. Appl. Opt., 50(22):4550-4556.

[3]Chu, X.C., Lü, H.B., Zhao, S.H., 2008. Research on long-range grating interferometry with nanometer resolution. Meas. Sci. Technol., 19(1):017001.

[4]Fleming, A.J., 2013. A review of nanometer resolution position sensors: operation and performance. Sens. Actuat. A, 190:106-126.

[5]Khorshad, A.A., Hassani, K., Tavassoly, M.T., 2012. Nanometer displacement measurement using Fresnel diffraction. Appl. Opt., 51(21):5066-5072.

[6]Lee, J.Y., Jiang, G.A., 2013. Displacement measurement using a wavelength-phase-shifting grating interferometer. Opt. Expr., 21(21):25553-25564.

[7]Li, N.H., Wu, W., Chou, S.Y., 2006. Sub-20-nm alignment in nanoimprint lithography using moiré fringe. Nano Lett., 6(11):2626-2629.

[8]Liu, C.M., Chen, L.W., Wang, C.C., 2006. Nanoscale displacement measurement by a digital nano-moiré method with wavelet transformation. Nanotechnology, 17(17):4359-4366.

[9]Oka, T., Ohmura, Y., Nakajima, H., et al., 2007. Displacement sensor based on grating imaging with a cylindrical lens array and a phase grating. Opt. Eng., 46(7):073603.

[10]Ramos, P.M., Serra, A.C., 2008. A new sine-fitting algorithm for accurate amplitude and phase measurements in two channel acquisition systems. Measurement, 41(2):135-143.

[11]Shao, J., Liu, H., Ding, Y., et al., 2008. Alignment measurement method for imprint lithography using moiré fringe pattern. Opt. Eng., 47(11):113604.

[12]Shao, J., Ding, Y., Tian, H., et al., 2012. Digital moiré fringe measurement method for alignment in imprint lithography. Opt. Laser Technol., 44(2):446-451.

[13]Suehira, N., Terasaki, A., Okushima, S., et al., 2007. Position measurement method for alignment in UV imprint using a high index mold and “electronic” moiré technique. J. Vac. Sci. Technol. B, 25(3):853-856.

[14]Vucijak, N.M., Saranovac, L.V., 2010. A simple algorithm for the estimation of phase difference between two sinusoidal voltages. IEEE Trans. Instr. Meas., 59(12):3152-3158.

[15]Wang, H., Wang, J., Chen, B., et al., 2015. Absolute optical imaging position encoder. Measurement, 67:42-50.

[16]Wu, D., Xie, H., Li, C., et al., 2014. Application of the digital phase-shifting method in 3D deformation measurement at micro-scale by SEM. Meas. Sci. Technol., 25:125002.

[17]Yuan, B., Yan, H.M., Cao, X.Q., 2009. A new subdivision method for grating-based displacement sensor using imaging array. Opt. Lasers Eng., 47(1):90-95.

[18]Zhao, S., Hou, C., Bai, J., et al., 2011. Nanometer-scale displacement sensor based on phase-sensitive diffraction grating. Appl. Opt., 50(10):1413-1416.