We report on experimental results in a new regime of relativistic light-matter interaction employing midinfrared (3.9−μm wavelength) high-intensity femtosecond laser pulses. In the laser-generated plasma, electrons reach relativistic energies already for rather low intensities due to the fortunate λ2 scaling of the kinetic energy with the laser wavelength. The lower intensity efficiently suppresses optical field ionization and creation of the preplasma at the rising edge of the laser pulse, enabling an enhanced efficient vacuum heating of the plasma. The lower critical plasma density for long-wavelength radiation can be surmounted by using nanowires instead of flat targets. Numerical simulations, which are in a good agreement with experimental results, suggest that ≈80% of the incident laser energy has been absorbed resulting in a long-living, keV-temperature, high-charge-state plasma with a density more than 3 orders of magnitude...

Im Rahmen der engen Zusammenarbeit zwischen Fertigung (FB 5.5) und Messtechnik (FB 4.2) in der PTB sind hochgenaue Referenzflächen gefertigt worden, die sich aus Kugelflächen zusammensetzen. Durch Rückführung der Sphärizität wurden die Referenzflächen im Rahmen des EMPIR-Projektes 15SIB01 erstmalig zur Überprüfung eines Asphären- und Freiformflächenmessgerätes verwendet.

Virtual experiments have become an indispensable tool for the design and the accuracy assessment of novel measurement procedures and instruments. Virtual experiments are particularly relevant in modern optics due to its challenging demands for highly accurate measurements. This paper introduces SimOptDevice, a flexible library for opto-mechanical virtual experiments. After describing the scope and general structure of the library, its underlying mathematical tools used for solving the related numerical tasks are described. Finally, the application of SimOptDevice to a recent interferometric measurement procedure is presented.