|Title||Nanoscale EUV Microscopy on a Tabletop: A General Transmission and Reflection Mode Microscope Based on Coherent Diffractive Imaging with High Harmonic Illumination|
|Year of Publication||2014|
|Number of Pages||192|
|University||University of Colorado|
A new scientic frontier exists at the intersection of the nanoscale and the ultrafast. In order to explore this frontier, new tools with unique capabilities for imaging with nanometer spatial and femtosecond temporal resolution are critical. This thesis describes the development of such a tool, combining coherent diffractive imaging (CDI) with an extreme ultraviolet (EUV) high harmonic generation (HHG) light source to produce a compact, accessible, high-resolution microscope. Here, this microscope is used to demonstrate 22 nm resolution in transmission, a record for any full-field tabletop light-based microscope. Further, this microscope is used to demonstrate the most general reflection mode implementation of CDI to date, enabling image reconstruction at any angle of incidence.
Chapter 2 describes the optimization of the HHG source for use with CDI. A pulse shaper is implemented to produce transform-limited pulses at 800 nm for increased HHG conversion efficiency. Furthermore, the long-term stability of the HHG source is improved by an order of magnitude through the pointing stabilization of the kHz driving laser. Chapter 3 develops the ideas necessary for the data processing techniques that enable general reflection mode CDI. Chapter 4 describes enhancements to the microscope to produce images with record 22 nm resolution in addition to extension of the microscope to image more complex, transmissive samples. Chapter 5 presents the most general implementation of reflection mode CDI to date. In chapter 6, the route towards dynamic femtosecond imaging of complex nanosystems is outlined, which includes potential for simultaneous hyperspectral EUV imaging across multiple absorption edges.