Digitale Holografie mit adaptiver Wellenfrontformung zur hochauflösenden Untersuchung von 3D-Mikrostrukturen im tiefen UV-Bereich
Zusammenfassung der Projektergebnisse
In the first part of this project we have developed a digital holographic microscope in deep UV, capable of recording 3D image from nanostructures. The setup has been designed with the least possible optical elements in the imaging path to avoid aberration due to the non-perfect optical elements. By implementing the oblique illumination method we are able to detect structures even down to 250 nm. The setup was implemented in a way to be able to image in transmission and reflection modes and was used for the investigation of nanostructures provided by industrial partners which are looking for methods suitable for the investigations of structures whose dimensions are down to the nano-scale. Unlike scanning systems, the digital holographic microscope developed during this project has the ability to extract the 3D information of the object by taking only one image and gives the possibility to derive the phase and amplitude information of the object wave-front in any plane that makes the holographic microscope more feasible and convenient. Moreover, it allows to investigate the shape and the displacements of objects in the nanoscale with high resolution and it highlights its capability as a promising 3D imaging technique. Despite the potential advantages of using Deep-ultraviolet (DUV, wavelengths below 300 nm) light in microscopy, e.g. enhanced lateral resolution and image contrast compared to visible light, this range of wavelength is considered to be toxic for biological applications. DUV is mostly absorbed by the protein and the amino acids inside the cellular structure that results in damaging the cell. For this reason, it has been rarely used for imaging biological samples. While the focus in the first part of the project was directed on technical samples, in the final state the investigations have been extended to bio-samples. An simple approach, based on using low irradiance DUV LED and phase retrieval methods has been implemented to extract the phase information, while having the least damaging effect on the cells. We demonstrated that due to the high sensitivity of DUV to the phase change, a more precise topographic profile of biological samples can be retrieved. This contrast enhancement together with the possibility to apply digital focusing makes the method very attractive for the investigation of cell.
Projektbezogene Publikationen (Auswahl)
- "Complete wavefront reconstruction using sequential intensity measurements of a volume speckle field," Appl. Opt. 45, 8596-8605 (2006)
P. Almoro, G. Pedrini, and W. Osten
- "Reconstruction algorithm for high-numericalaperture holograms with diffraction-limited resolution," Opt. Lett. 31,1633-1635 (2006)
F. Zhang, G. Pedrini, and W. Osten
- Phase retrieval of arbitrary complex-valued fields through aperture plane modulation“, Phys. Rev. A 75, 043805 (2007)
F. Zhang, G. Pedrini, W. Osten
- Wavefront sensing with random amplitude mask and phase retrieval”, Opt. Lett. 32, 1584-1586 (2007)
A., Anand, G. Pedrini, W. Osten, P. Almoro
- “Aperture synthesis in phase retrieval using a volume speckle field”, Opt. Lett. 32, 733-735 (2007)
P. Almoro, G. Pedrini, W. Osten
- “Digital holographic microscopy in the deep (193 nm) ultraviolet”, Appl. Opt. 46(32), 7829-7835 (2007)
G. Pedrini, F.C. Zhang, W. Osten
- “Coherence effects in digital in-line holographic microscopy,” JOSA A, 25, 2459-2466 (2008)
U. Gopinathan, G. Pedrini, W. Osten
- “Nanoscale imaging using deep ultraviolet digital holographic microscopy,” Opt. Express, 18(13), 14159-14164 (2010)
A. Faridian, D. Hopp, G. Pedrini, U. Eigenthaler, M. Hirscher, W. Osten
- “High-resolution quantitative phase microscopic imaging in deep UV with phase retrieval”, Optics Letters, Vol. 36 Issue 22, pp.4362-4364 (2011)
A. Anand, A. Faridian, V. Chhaniwal, G. Pedrini, W. Osten, B. Javidi
- “Lensless phase microscopy using phase retrieval with multiple illumination wavelengths”, Applied Optics, Vol. 51 Issue 22, pp.5486-5494 (2012)
P. Bao, G. Situ, G. Pedrini, W. Osten
(Siehe online unter https://doi.org/10.1364/AO.51.005486)
