## 4 Discussion and Conclusions  
The SXR and EUV desktop microscopes, both full-field and contact-type, recently developed at the Institute of Optoelectronics, Military University of Technology, Warsaw, Poland, for imaging nanoscale objects were presented. All microscopes are based on laser plasma sources producing the EUV and SXR radiations through interaction of nanosecond laser pulses with double stream gas puff target. The imaging systems allow capturing magnified images of the samples, with 50-80 nm half-pitch spatial resolution and exposure time as low as few seconds. The microscopes are compact and allow obtaining images with a nanometer spatial resolution and short exposure time, which may open the possibility of their future commercialization. Those systems employing photons and not electrons, like in SEM, can obtain additional/complementary information about the sample under investigation. Moreover, those systems do not require coating with a conductive layer, such as in the SEM microscopes, to remove surface charges accumulated during the imaging. Although their spatial resolution cannot compete with electron based systems, it is much better that the visible light microscopes and comparable to synchrotron based microscopy systems and to Stimulated Emission Depletion microscopy (STED) [42; 43]. Such table-top systems allow for a direct acquisition of a full field images, in contrary to STED acquisition operating in scanning mode, and do not require fluorescent bio markers or staining that modifies the morphology of the sample. Additionally, they use wavelengths that provide high optical contrast, either in biological (SXR microscope) or in all matter with thicknesses less than a few hundred nanometers (EUV microscope). To distinguish between EUV/SXR full field microscopes and SXR contact microscope one has to notice, however, that although the contact microscopy lacks expensive optics and allows for high spatial resolution, limited in principle by the resolution of the underlying photoresist (for PMMA \(\sim\)10 nm), the contact microscopy procedure causes the sample to be destroyed after imaging. It is because the resist, with the sample located on top, is being developed chemically after the exposure, which causes the sample to be irreversibly lost. In full-field microscopes the sample is located at some distance from the objective, without any contact with optics, detectors, etc., and can be later studied using other techniques (VIS, SEM, AFM microscopes, etc. ), however, for the price of costly and still optically inefficient EUV and SXR optics. So, the choice of the technique is always related directly to the information that one wants to obtain from the samples investigated. This work is supported by the National Science Centre, Opus program, grant agreement number UMO-2015/17/B/ST7/03718 and UMO-2015/19/B/ST3/00435, the National Centre for Research and Development, LIDER program; award # LIDER/004/410/L-4/12/NCBR/2013, the Education, Audoviusal and Culture Executive Agency (EACEA) Erasmus Mundus Joint Doctorate Program Project No. 2012-0033 and from the European Union's Horizon 2020 research and innovation program, under LaserLab-Europe IV, grant agreement No. 654148. The preparation of the biological cells has been supported by MEYS grant LG15013. We would like to thank to [PERSON] and [PERSON], from the Institute of Electronic Materials Technology (ITME), Warsaw, Poland for the preparation of the photoresist in their laboratory. We also acknowledge [PERSON] and [PERSON], from the Faculty of Chemistry Warsaw University of Technology and [PERSON], from the institute of Nuclear Physics Krakow, Poland for providing the biological samples used for contact microscopy experiments.