Microscope for investigating the size of an EUV radiation source emitting at 11.2 nm

Abstract In this article, we report on the development, construction and operation of a microscope to study the emission radiation of laser plasma in the EUV spectral range. The main optical unit of the microscope is a two-mirror spherical Schwarzschild objective with a 5x magnification. The microscope builds an image of the plasma cloud at a wavelength of 11.25 nm. This wavelength is determined by the manufactured multilayer x-ray mirrors based on a Mo/Be structure. To suppress the long-wave noise component of the signal in the VUV, UV, visible and IR spectral range, we used two thin-film Mo/Be filters. The device was calibrated on the basis of both EUV radiation registration efficiency and spatial resolution at the operating wavelength, these being 12% and 3.9 μm, respectively. We also discuss the results of studying the size of a laser spark in gas-jet targets.