Impact of free electron laser coherence on imaging quality
Shuang Wei(魏爽)1, Shuang Gong(龚爽)2,†, Yang Bu(步扬)3,‡, and Zi-Jian Song(宋子健)1
1 School of Microelectronics, Shanghai University, Shanghai 200444, China; 2 Zhangjiang Laboratory, Shanghai 201210, China; 3 Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Shanghai 201800, China
Abstract The high temporal and spatial coherence of free electron lasers (FELs) reduces the uniformity of the illumination field, leading to scattering effects that blur the edges of patterns, resulting in diminished accuracy and clarity. Traditional imaging models regard the light source as fully incoherent, making it difficult to assess the impact of partially coherent light fields on imaging. If FELs are used in imaging systems, their coherence must be considered. To address this issue, this study explores the relationship between coherence, imaging quality and speckle contrast through a simulation method based on random phases. The method divides the light beam into temporal and spatial coherence cells, analyzes their interactions, and simulates imaging results under different coherence conditions. Additionally, speckle patterns for various illumination modes are calculated to evaluate their effects on speckle contrast and illumination uniformity. The results indicate that under different illumination modes, illumination uniformity decreases as coherence increases, while speckle contrast increases with higher coherence. In terms of imaging quality, higher coherence leads to an increase in both line edge roughness (LER) and line width roughness (LWR), thereby reducing the imaging quality. Additionally, the narrower the line width, the greater the impact of coherence on the imaging quality, resulting in poorer imaging performance.
Corresponding Authors:
Shuang Gong, Yang Bu
E-mail: gongshuang@zjlab.ac.cn;buyang@siom.ac.cn
Cite this article:
Shuang Wei(魏爽), Shuang Gong(龚爽), Yang Bu(步扬), and Zi-Jian Song(宋子健) Impact of free electron laser coherence on imaging quality 2025 Chin. Phys. B 34 054201
[1] Kwan T, Dawson J M and Lin A T 1977 The Free Electron Laser (Springer) pp. 486-506 [2] Kim K J, Huang Z and Lindberg R 2017 Synchrotron Radiation and Free-Electron Lasers (Cambridge: Cambridge University Press) pp. 23-25 [3] Madey J M 1971 J. Appl. Phys. 42 1906 [4] Cardman L S, Harwood L and Jefferson T 2008 2007 IEEE Particle Accelerator Conf. (PAC), June 22-26, 2007, Albuquerque, United States of America, p. 58 [5] Benson S V, Beard K, Behre C, Biallas G H, Boyce J, Douglas D, Dylla F 2004 High power lasing in the IR Upgrade FEL at Jefferson Lab Thomas Jefferson National Accelerator Facility (TJNAF) (VA: USA) [6] Kulipanov G N, Bagryanskaya E G, Chesnokov E N, Choporova Y Y, Gerasimov V V, Getmanov Y V and Vinokurov N A 2015 IEEE Trans. on Terahertz Science and Technology 5 798 [7] Thompson N R, Clarke J A, Craig T, Dunning D J, Kolosov O V, Moss A and Weightman P 2015 Proceedings of the 37th Int. Free Electron Laser Conf., 2015, Daejeon, Korea, p. 379 [8] Ben-Zvi I, Derbenev Y, Litvinenko V N and Merminga L 2006 Nuclear Instruments and Methods in Physics Research Section A 557 28 [9] Wang G, Chao Y C, Liu C, Zhao K, Lu X, Zhuang J and Chen J 2007 IEEE Particle Accelerator Conf. (PAC), June 25-29, 2007, Albuquerque, United States of America, p. 1191 [10] Huang S L, Liu K X, Quan S W, Lin L, Zhu F and Chen J E 2011 ii Preface 2007 2005 [11] Chen S, Huang S L, Li Y M, Feng L W, Zhu F, Quan S W and Chen J E 2013 Chin. Phys. C 37 087001 [12] Socol Y, Kulipanov G N, Matveenko A N, Shevchenko O A and Vinokurov N A 2011 Phys. Rev. Spec. Top. Accel. Beams 14 040702 [13] Socol Y, Kulipanov G N, Shevchenko O A, Vinokurov N A and Matveenko A N 2010 13.5 nm Proc. FEL 28 250 [14] Goldstein M, Lee S H, Shroff Y A, Silverman P J, Williams D, Park H and Pantell R H 2005 Proc. 2005 FEL Conf., August 21-26, Stanford, California, United States of America, p. 422 [15] Chen M, Chen L, Zeng A, Zhu J, Yang B and Huang H 2015 Applied Optics 54 6820 [16] Voelkel R 2014 Optical Microlithography XXVII, March, 31, 2014, San Jose, California, United States of America, p. 530 [17] Chang C, Naulleau P, Anderson E and Attwood D 2000 Opt. Commun. 182 25 [18] Anderson C N, Miyakawa R H and Naulleau P P 2011 Extreme Ultraviolet (EUV) Lithography II, April, 8, 2011, San Jose, California, United States of America, p. 986 [19] Naulleau P P, Anderson C N, Dean K, Denham P, Goldberg K A, Hoef B and Wallow T 2007 Emerging Lithographic Technologies XI March, 15, 2007, San Jose, California, United States of America, p. 265 [20] Goodman J W 2005 Introduction to Fourier Optics (Greenwood Village: Roberts and Company Publishers) p. 56 [21] Gbur G and Visser T D 2022 Progress in Optics 67 275 [22] Young T 1802 Phil. Trans. Roy. Soc. Lond. 92 387 [23] Kim Y, Seo H and Park J 2013 Journal of Gifted/Talented Education 23 817 [24] Wolf E 1986 JOSA A 3 76 [25] Mandel L 1995 Optical Coherence and Quantum Optics (Cambridge: Cambridge University Press) p. 59 [26] Zernike F 1938 Physica 5 785 [27] Mandel L and Wolf E 1976 JOSA 66 529 [28] Goodman J W 2007 Speckle Phenomena in Optics: Theory and Applications (Greenwood Village: Roberts and Company Publishers) pp. 89-113 [29] Kim S K 2021 Micromachines 12 1493 [30] Stulen R H and Sweeney D W 1999 IEEE J. Quantum Electron. 35 694 [31] Murakami K, Oshino T, Kondo H, Chiba H, Komatsuda H, Nomura K and Iwata H 2008 Emerging Lithographic Technologies XII, March, 20, 2008, San Jose, California, United States of America, p. 222 [32] Antoni M, Singer W, Schultz J, Wangler J, Escudero-Sanz I and Kruizinga B 2000 Soft X-Ray and EUV Imaging Systems, November, 8, 2000 San Jose, California, United States of America, p. 25-34 [33] Constantoudis V, Papavieros G, Karakolis P, Khiat A, Prodromakis T and Dimitrakis P 2019 Materials 12 3972 [34] Brunner T A, Chen X, Gabor A, Higgins C, Sun L and Mack C A 2017 Extreme Ultraviolet (EUV) Lithography VIII, March, 24, 2017, San Jose, California, United States of America, p. 48 [35] Kim S K 2021 Micromachines 12 1493
Altmetric calculates a score based on the online attention an article receives. Each coloured thread in the circle represents a different type of online attention. The number in the centre is the Altmetric score. Social media and mainstream news media are the main sources that calculate the score. Reference managers such as Mendeley are also tracked but do not contribute to the score. Older articles often score higher because they have had more time to get noticed. To account for this, Altmetric has included the context data for other articles of a similar age.
