Advanced Optical Imaging with Scattering Lenses


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TitleAdvanced Optical Imaging with Scattering Lenses
Publication TypeThesis
Year of Publication2015
AuthorsH. Yılmaz
Date Published07/2015
UniversityUniversity of Twente
Thesis TypePhD
Keywordscomputational imaging, light microscopy, Light scattering, optical imaging, Wavefront shaping
Abstract

This thesis describes new advanced optical methods to control light propagation through disordered nanophotonic materials for focusing and high‐resolution imaging applications. A combination of light scattering, wavefront control, and our new image processing algorithms enable using random nanophotonic materials as optical lenses.

We have demonstrated optimal focusing of coherent light through scattering media in the presence of experimental noise. We found that our algorithm suppresses the camera read‐out noise and brings the experiment into a shot‐noise limited regime. Our results bring new insights to wavefront shaping experiments from an information‐theoretical point of view.

High‐index substrates of silicon (Si) or gallium phosphide (GaP) are essential materials for high‐ resolution solid immersion microscopy. Previously, a scattering solid immersion lens (SSIL) has been reported which enables sub‐100 nm resolution with visible light. Until now there was no convenient method to characterize SSILs. We have developed a new optical characterization method that enables measurement of high internal‐angle scattering of high‐index substrates. We have confirmed that a SSIL with an unpolished rough surface is at least as good as a SSIL with a thick scattering layer for sub‐100 nm optical imaging.

We have developed speckle correlation resolution enhancement (SCORE) imaging that simultaneously produces wide‐field and high‐resolution fluorescence images. SCORE is a scanning optical microscopy method that benefits from a speckle correlation effect, known as the optical memory effect. The high‐resolution of SCORE is due to very fine speckle patterns that are generated by a solid immersion medium which is made of a gallium phosphide (GaP) substrate with a scattering layer. We demonstrate a deconvolved Abbe resolution of 116 nm with a field‐of‐view of 10 µm × 10 µm.

Seeking to improve even the high resolution of SCORE, we have developed and presented a new high‐resolution fluorescence imaging method that is based on periodically patterned light illumination through scattering medium. Our wide‐field and high‐contrast fluorescence imaging method enables sub‐Abbe‐resolution images of surfaces. In our initial demonstration we have demonstrated a significant improvement both in resolution and contrast, however we have not reached the theoretical limit yet.

Group

COPS

List number

15.01

Promotor(s)

Prof. Dr. Allard P. Mosk

AttachmentSize
150701_Yilmaz_PhD_thesis.pdf8.58 MB