GOBO projection for 3D measurements at highest frame rates: a performance analysis

Aperiodic sinusoidal patterns that are cast by a GOBO(GOes Before Optics)projector are a powerful tool for optically measuring the surface topography of moving or deforming objects with very high speed and accuracy.We optimised the first experimental setup that we were able to measure inflating car airbags at frame rates of more than 50 kHz while achieving a 3D point standard deviation of~500μm.Here,we theoretically investigate the method of GOBO projection of aperiodic sinusoidal fringes.In a simulation-based performance analysis,we examine the parameters that influence the accuracy of the measurement result and identify an optimal pattern design that yields the highest measurement accuracy.We compare the results with those that were obtained via GOBO projection of phase-shifted sinusoidal fringes.Finally,we experimentally verify the theoretical findings.We show that the proposed technique has several advantages over conventional fringe projection techniques,as the easy-to-build and cost-effective GOBO projector can provide a high radiant flux,allows high frame rates,and can be used over a wide spectral range.

Petawatt and exawatt class lasers worldwide

In the 2015 review paper‘Petawatt Class Lasers Worldwide’a comprehensive overview of the current status of highpower facilities of>200 TW was presented.This was largely based on facility specifications,with some description of their uses,for instance in fundamental ultra-high-intensity interactions,secondary source generation,and inertial confinement fusion(ICF).With the 2018 Nobel Prize in Physics being awarded to Professors Donna Strickland and Gerard Mourou for the development of the technique of chirped pulse amplification(CPA),which made these lasers possible,we celebrate by providing a comprehensive update of the current status of ultra-high-power lasers and demonstrate how the technology has developed.We are now in the era of multi-petawatt facilities coming online,with 100 PW lasers being proposed and even under construction.In addition to this there is a pull towards development of industrial and multi-disciplinary applications,which demands much higher repetition rates,delivering high-average powers with higher efficiencies and the use of alternative wavelengths:mid-IR facilities.So apart from a comprehensive update of the current global status,we want to look at what technologies are to be deployed to get to these new regimes,and some of the critical issues facing their development.

Material-specific high-resolution table-top extreme ultraviolet microscopy

Microscopy with extreme ultraviolet(EUV)radiation holds promise for high-resolution imaging with excellent material contrast,due to the short wavelength and numerous element-specific absorption edges available in this spectral range.At the same time,EUV radiation has significantly larger penetration depths than electrons.It thus enables a nano-scale view into complex three-dimensional structures that are important for material science,semiconductor metrology,and next-generation nano-devices.Here,we present high-resolution and material-specific microscopy at 13.5 nm wavelength.We combine a highly stable,high photon-flux,table-top EUV source with an interferometrically stabilized ptychography setup.By utilizing structured EUV illumination,we overcome the limitations of conventional EUV focusing optics and demonstrate high-resolution microscopy at a half-pitch lateral resolution of 16 nm.Moreover,we propose mixed-state orthogonal probe relaxation ptychography,enabling robust phase-contrast imaging over wide fields of view and long acquisition times.In this way,the complex transmission of an integrated circuit is precisely reconstructed,allowing for the classification of the material composition of mesoscopic semiconductor systems.