Next Generation Laboratory Soft X-Ray Microscope for 3D Nanoimaging

Recent advancements in microscopy techniques are continually pushing the boundaries of our understanding of cellular structures and functions. Soft X-ray microscopy in the water window region of the electromagnetic spectrum is a powerful technique for high-resolution 3D imaging of biological samples. The natural contrast between carbon structures and cellular water allows for high resolution imaging while preserving structural integrity through cryo-fixation. Traditionally performed at synchrotrons, the limited number of soft X-ray beamlines has hindered wider accessibility. Developing a laboratory based source would significantly broaden access, particularly benefiting biologists. This PhD research focuses on enhancing the soft X-ray intensity at the sample plane to empower laboratory-based microscopy. The goal is to enable the microscope to produce 3D tomography images that are of a comparable quality to those obtained at synchrotrons, all within a practical and acceptable timeframe. This has been achieved by (a) increasing the radiance of the microscope source by an order of magnitude and (b) enhancing the overall efficiency of the soft X-ray beamline to the sample by an order of magnitude, by demonstrating the performance of new optics. A high-power laser was initially acquired, complemented by the integration of advanced, higher-specification optics into the microscope. To further optimize performance, a second laser with a shorter pulse width was also tested. I, along with the team at SiriusXT, designed a series of experiments to measure the impact of these enhancements on the other components of the microscope. My research examined various source parameters, including laser repetition rate (750Hz-2kHz), pulse energy (14mJ-60mJ), and pulse-width (2.5ns-6ns). Additionally, I characterized improvements in soft X-ray optics. The insights gained from these investigations have already guided enhancements to the microscope’s capabilities, paving the way for advancements in soft X-ray microscopy research and providing biologists with high-performance tools for exploring cellular ultrastructure.