Generation and Application of Coherent Extreme Ultraviolet Radiation

High harmonic generation featuring ultra-short pulses, short wavelengths and highly coherent radiation in a table-top setup has become one of the most versatile and affordable tools for studies of atomic and molecular dynamics as well as for nano-scale coherent diffractive imaging. In this book, we show the background and technical aspects of the generation and enhancement of high order harmonic radiations down to the water window region (2.3 - 4.4 nm). The source is specifically tailored and developed for imaging applications. By controlling and stabilizing the phase-matching condition in a gas cell, an extreme ultra-violet source which satisfies these requirements has been generated. Using a harmonic source with wavelengths around 30 nm, a resolution of 45 nm for a micrometer-size transmission sample has been obtained and biological-like absorption samples are also successfully reconstructed. A phase retrieval algorithm with a phase-curvature correction is developed to take advantage of the higher photon flux when placing the sample near the focus point.