Spatial coherence measurements of the EUV emission from laser-plasma source based on xenon/helium gas puff target

Abstract

employed for important achievements in diffraction imaging [7], high-resolution holography [8], among others.Among compact sources, there are also sources that use gas-type targets to produce laser-plasma-emitting short wavelength radiation. These sources are often referred to as sources based on gas jets [9]. Variations of those are double stream gas puff targets, which inject not one but two gasses into the interaction region. While the inner gas is called working gas, which is the material of the target, to which a specific elemental emission can be attributed, the other, outer gas surrounds the inner gas shaping its flow and increasing its density in the interaction region. Such source was already proven to be useful so far for various applications in metrology [10], full-field imaging [11], photoionization [12], polymer surface modification [13], radiobiology [14], etc. All those applications were related to the use of spatially incoherent EUV and SXR radiation; however, to this day, it was never used for coherent-type applications.In this work, we would like to present the first to our knowledge attempt to obtain partially coherent EUV emission with usable photon flux from xenon/helium plasma, to perform coherent imaging experiments. We present the spatial coherence measurements, performed using Young double slit interferometry and demonstration of the use of such spatially coherent radiation to imaging. In the following chapters, the details about this work will be presented and discussed. Experimental setupThe experimental setup for spatial coherence measurements of the emission from xenon plasma is depicted in Fig. 1a. An Nd:YAG laser beam, produced by NL 129 laser system (10 J/1-10 ns), from EKSPLA, Lithuania, having Abstract In this paper, we present the first measurements of the partial spatial coherence of the EUV emission from xenon plasma in laser-plasma source, based on a double stream gas puff target. The Young double slit approach was employed to measure complex coherence factor of the EUV Xe emission at 13.5-nm wavelength in two orthogonal directions. The radius of coherence of ~60 μm was estimated at the distance of 2.1 m from the source. The number of coherently emitted photons was sufficient to demonstrate coherent imaging. Using partially coherent radiation from such source Gabor EUV holography was successfully demonstrated.