Abstract
Diffractive lens arrays with overlapping apertures can produce spot arrays with high numerical apertures (NAs). Combined with low-NA objectives, they can measure a large area with high lateral resolution. However, for surface measurements, the axial resolution of such setups is still fundamentally limited by the objectives. In this work, we propose a new design of diffractive optical elements (DOEs) to overcome this problem. The proposed Direct-imaging DOEs can perform 3D high-NA multi-spot surface measurements. Laterally, a non-vanishing contrast up to 1448 lp/mm is measured with a USAF resolution target. Axially, an average height of 917.5 nm with a standard deviation of 49.9 nm is measured with a calibrated step height target of 925.5 nm.
Zusammenfassung
Diffraktive Linsenarrays mit überlappenden Aperturen können Spot-Arrays mit hohen numerischen Aperturen (NAs) erzeugen. Kombiniert mit Low-NA-Objektiven können sie einen großen Bereich mit hoher lateraler Auflösung messen. Für Oberflächenmessungen ist die axiale Auflösung solcher Aufbauten jedoch immer noch grundlegend durch die Objektive begrenzt. In dieser Arbeit schlagen wir ein neues Design von diffraktiven optischen Elementen (DOEs) vor, um dieses Problem zu lösen. Die vorgeschlagenen Direct-imaging DOEs können 3D-Multispot-Oberflächenmessungen mit hohen NA durchführen. Lateral wird ein nicht verschwindender Kontrast bis zu 1448 lp/mm mit einem USAF Auflösungstest gemessen. Axial wird eine durchschnittliche Höhe von 917.5 nm mit einer Standardabweichung von 49.9 nm bei einem kalibrierten Stufenhöhentarget von 925.5 nm gemessen.
About the authors
Zheng Li received his Master’s degree from Karlsruhe School of Optics & Photonics (KSOP) at Karlsruhe Institute of Technology (KIT) in 2016 and his Bachelor’s degree from School of Mechanical Engineering at Shanghai Jiao Tong University (SJTU) in 2013. Since September 2016, he has joined Vision and Fusion Laboratory (IES) as a doctor candidate. His research interests include electromagnetic simulation, diffractive optics and microscopy.
Miro Taphanel studied mechanical engineering at the University of Karlsruhe and received his diploma with distinction in 2010. He received his doctor degree in Vision and Fusion Laboratory (IES). His field of work is optical metrology for dimensional and material sensing tasks. The work takes place in close cooperation with the Department of Visual Inspection Systems (SPR) at Fraunhofer IOSB in Karlsruhe. Currently he serves as the CEO of Gixel GmbH.
Thomas Längle is adjunct professor at Karlsruhe Institute of Technology (KIT) and the head of the business unit “Vision Based Inspection Systems” (SPR) at Fraunhofer IOSB in Karlsruhe, Germany. His research interests included different aspects of image processing and real-time algorithms for inspection systems.
Jürgen Beyerer has been a full professor for informatics at the Institute for Anthropomatics and Robotics at the Karlsruhe Institute of Technology (KIT) since March 2004 and director of the Fraunhofer Institute of Optronics, System Technologies and Image Exploitation (IOSB) in Ettlingen, Karlsruhe, Ilmenau, Lemgo and Görlitz. He is Spokesman of the Fraunhofer Group for Defense and Security VVS and he is member of acatech, National Academy of Science and Engineering. Furthermore, he is Head of team 7 of the platform “Lernende Systeme” and Spokesman of the Competence Center Robotic Systems for Decontamination in Hazardous Environments (ROBDEKON). Research interests include automated visual inspection, signal and image processing, pattern recognition, metrology, information theory, machine learning, system theory security, autonomous systems and automation.
References
1. K. Brenner, T. Stenau and M. Azizian. Entwicklung eines scannenden Mikroskops mit diffraktiven Mikrolinsen. In Online-Zeitschrift der Deutschen Gesellschaft für angewandte Optik e. V., Braunschweig, May 2013.Search in Google Scholar
2. E. Dai, C. Zhou, P. Xi and L. Liu. Multifunctional double-layered diffractive optical element. Optics Letters, 28 (17): 1513–1515, 2003.10.1364/OL.28.001513Search in Google Scholar PubMed
3. P. de Groot and D. Fitzgerald. Measurement, certification and use of step-height calibration specimens in optical metrology. In P. Lehmann, W. Osten and A. Albertazzi Gonçalves, Jr., editors, Optical Measurement Systems for Industrial Inspection X, Volume 10329, pp. 328–336. International Society for Optics and Photonics, SPIE, 2017. 10.1117/12.2269800.Search in Google Scholar
4. A. Forbes, P. Harris and R. K. Leach. The comparison of algorithm for the assessment of type a1 surface texture reference artefacts. Technical Report CMSC 33/03, National Physical Laboratory, 2018.Search in Google Scholar
5. B. Hulsken, D. Vossen and S. Stallinga. High NA diffractive array illuminators and application in a multi-spot scanning microscope. Journal of the European Optical Society – Rapid Publications, 7, 2012.10.2971/jeos.2012.12026Search in Google Scholar
6. Z. Li. Application of diffractive optical elements in confocal microscopy. In M. Taphanel and J. Beyerer, editors, Proceedings of the 2018 Joint Workshop of Fraunhofer IOSB and Institute for Anthropomatics, Vision and Fusion Laboratory. KIT Scientific Publishing, Karlsruhe, 2019.Search in Google Scholar
7. Z. Li, M. Taphanel, T. Längle and J. Beyerer. Direct-imaging DOEs for high-NA multi-spot confocal microscopy. tm - Technisches Messen, 87 (s1): s40–s43, 01 Sep. 2020. 10.1515/teme-2020-0017.Search in Google Scholar
8. Z. Li, M. Taphanel, T. Längle and J. Beyerer. Application of DOE in confocal microscopy for surface measurement. In M. Rosenberger, P.-G. Dittrich and B. Zagar, editors, IMEKO Joint TC1–TC2 International Symposium on Photonics and Education in Measurement Science, Volume 11144, pp. 254–261. International Society for Optics and Photonics, SPIE, 2019.10.1117/12.2531610Search in Google Scholar
9. X. Liu and K.-H. Brenner. High resolution wavefront measurement with phase retrieval using a diffractive overlapping micro lens array. In W. Osten, editor, Fringe 2013, pp. 233–236. Springer Berlin Heidelberg, Berlin, Heidelberg, 2014. ISBN 978-3-642-36359-7.10.1007/978-3-642-36359-7_35Search in Google Scholar
10. A. Orth and K. Crozier. Microscopy with microlens arrays: high throughput, high resolution and light-field imaging. Opt. Express, 20 (12): 13522–13531, Jun 2012. 10.1364/OE.20.013522.Search in Google Scholar PubMed
11. A. Orth and K. B. Crozier. High throughput multichannel fluorescence microscopy with microlens arrays. Opt. Express, 22 (15): 18101–18112, Jul 2014. 10.1364/OE.22.018101.Search in Google Scholar PubMed
12. S. Pang, C. Han, J. Erath, A. Rodriguez and C. Yang. Wide field-of-view Talbot grid-based microscopy for multicolor fluorescence imaging. Opt. Express, 21 (12): 14555–14565, Jun 2013. 10.1364/OE.21.014555.Search in Google Scholar PubMed PubMed Central
13. F. Shen and A. Wang. Fast-Fourier-Transform based numerical integration method for the Rayleigh-Sommerfeld diffraction formula. Applied Optics, 45 (6): 1102–1110, 2006.10.1364/AO.45.001102Search in Google Scholar PubMed
14. A. Sommerfeld. Mathematische Theorie der Diffraction. Mathematische Annalen, 47 (2): 317–374, 1896.10.1007/BF01447273Search in Google Scholar
15. A. Sommerfeld. Mathematical Theory of Diffraction. Birkhäuser Boston, Boston, MA, 2004. ISBN 978-0-8176-8196-8. 10.1007/978-0-8176-8196-8_2.Search in Google Scholar
16. T. Stenau and K.-H. Brenner. Diffractive lenses with overlapping aperture a new tool in scanning microscopy. In Imaging Systems and Applications, p. IT1F–1. Optical Society of America, 2016.10.1364/ISA.2016.IT1F.1Search in Google Scholar
17. Y. Sun and S. Pang. Multi-perspective scanning microscope based on Talbot effect. Applied Physics Letters, 108 (2): 021102, 2016.10.1063/1.4939873Search in Google Scholar
18. G. J. Swanson. Binary optics technology: the theory and design of multi-level diffractive optical elements. Technical report, Lincoln Laboratory, Massachusetts Institute of Technology, 1989.10.21236/ADA213404Search in Google Scholar
19. VLSI Standards. Application note: Step height standards for use with KLA-Tencor instruments, 2010. Rev.AB.Search in Google Scholar
20. T. Wilson. Resolution and optical sectioning in the confocal microscope. Journal of Microscopy, 244 (2): 113–121, 2011.10.1111/j.1365-2818.2011.03549.xSearch in Google Scholar PubMed
21. T. Wilson and C. Sheppard. Theory and Practice of Scanning Optical Microscopy, Volume 180. Academic Press London, 1984.Search in Google Scholar
22. J. Wu, X. Cui, G. Zheng, Y. M. Wang, L. M. Lee and C. Yang. Wide field-of-view microscope based on holographic focus grid illumination. Opt. Lett., 35 (13): 2188–2190, Jul 2010. 10.1364/OL.35.002188.Search in Google Scholar PubMed
23. G. Zheng. Fourier Ptychographic Imaging: A Matlab Tutorial. Morgan & Claypool Publishers, 2016.10.1088/978-1-6817-4273-1Search in Google Scholar
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