## EUV and SXR Full Field Microscopes Based on a Double Stream Gas-Puff Target Source
### SXR Tomography and 3D Imaging  
The SXR equipment was later improved in order to acquire 3D images, i.e., topography of the samples [59]. An Nd:YAG (YG981, from Quantel, MT, USA), with a pulse duration of 8 ns, 20 Hz repetition rate, and an energy of 1.5 J was employed. The photon flux of the source, at the sample plane, was of \(\sim\)9 \(\times\) 10\({}^{9}\) photons/pulse at 2.88 nm wavelength. The experimental setup is depicted in Figure 11a, while the internal components of the microscope are shown in Figure 11b. The system was  
Figure 10: (**a**) Optical and (**b**) SXR image of a #2000 TEM copper mesh. Insets in (**b**) shows some defects, including \(\sim\)200 nm wide features. (**c**) Shows the knife-edge test, performed on the base of the white-dotted line in (**b**). Figure modified, based on [80].  
equipped with a piezoelectric translation stage (Q-545.240, travel range of 26 mm, 1 nm resolution, and bidirectional repeatability of \(\pm\)18 nm) and a rotation stage (Q-632.930, rotation range \(>\)360\({}^{\circ}\), 0.75 \(\upmu\)rad sensor resolution, and unidirectional repeatability 6 \(\upmu\)rad), from Pi miCos, to move the sample to observe with nanometric precision. Thus, according to the type of sample to observe, two different sample holders, machined ad hoc, can be mounted inside the chamber: a tip-holder (Figure 11c), on the top of which it is possible to place samples in granular form, and a slit-holder (Figure 11d), having a width of 0.21 mm and a depth of 1 mm, which can host a standard TEM Si\({}_{3}\)N\({}_{4}\) membrane (typically 30 nm thick), on the top of which are typically deposited a few drops of a liquid sample [59]. The slit-holder, having a slot 0.5 mm deep and 0.5 mm wide, ensures that the Si\({}_{3}\)N\({}_{4}\) membrane can be visible for a large range of rotation angles. The rotation angles range is limited to the geometry of the holder, \(\pm\)60\({}^{\circ}\) from normal incidence illumination. The holders are positioned on a rotation stage and the rotation axis of the sample is located 140 mm from the condenser exit plane, in its focal point. To avoid eccentricity, for both the holders, it is required an accurate alignment of their rotation axis with the rotation axis of the stage.  
The projections acquisition was optimized cooling down the CCD camera at a temperature of \(-\)20 \({}^{\circ}\)C, in order to reduce its internal noise and to improve the SNR of the acquired images. The tomography system consents to acquire the projections using two different CCD cameras, inside or outside the microscopy chamber. An Andor i-Kon, DX-420-BN camera, 256 \(\times\) 1024 pixels (25 \(\times\) 25 \(\upmu\)m\({}^{2}\) pixel size) can be placed inside the microscope vacuum chamber at a distance of \(\sim\)270 mm from the FZP, resulting in a (geometric) magnification of \(\sim\)100\(\times\) (sample--CCD camera). Alternatively, a second camera, Andor i-Kon, DO-934N-BN, 1024 \(\times\) 1024 pixels (13 \(\times\) 13 \(\upmu\)m\({}^{2}\) pixel size), can be located externally to the microscope vacuum chamber, at a distance of 530 mm from the FZP, resulting in a magnification of \(\sim\)200\(\times\). In this second case, the resulting FOV is 60 \(\times\) 60 \(\upmu\)m\({}^{2}\), while the spatial resolution is \(\sim\)60 nm [59]. The employment of the internal CCD camera, instead, limits horizontally the FOV, resulting in 150 \(\times\) 60 \(\upmu\)m\({}^{2}\); however, the spatial resolution of the 2D projections is limited by the detector sampling to \(\sim\)250 nm. Even though the external camera allows the acquisition of 2D projections with higher resolution and magnification, the use of the internal camera results easier and more useful for imaging of the samples whose axis of rotation is unknown, and must be determined by rotating the sample several times, compensating for the offset, according to its distribution.