Results 41 to 50 of about 504,859 (272)
Scientific Reports, 2017 In this paper, we experimentally validate a tiled-aperture conformal projection system with the largest array filling factor and element beam truncation factor to the best of our knowledge. The conformal projection system, which is made up of a hexagonal
Dong Zhi +7 more
doaj +1 more source
Heat-machine control by quantum-state preparation: from quantum engines to refrigerators [PDF]
Physical Review E 90, 022102 (2014), 2013 We explore the dependence of the performance bounds of heat engines and refrigerators on the initial quantum state and the subsequent evolution of their piston, modeled by a quantized harmonic oscillator. Our goal is to provide a fully quantized treatment of self-contained (autonomous) heat machines, as opposed to their prevailing semiclassical ...
arxiv +1 more source
Deep learning piston aberration control of fiber laser phased array by spiral phase modulation [PDF]
, 2021 The stochastic parallel gradient descent (SPGD) algorithm is usually employed as the control strategy for phase-locking in fiber laser phased array systems. However, the convergence speed of the SPGD algorithm will slow down as the number of array elements increases.
arxiv +1 more source
Single conjugate adaptive optics for the ELT instrument METIS [PDF]
, 2018 The ELT is a 39m large, ground-based optical and near- to mid-infrared telescope under construction in the Chilean Atacama desert. Operation is planned to start around the middle of the next decade.
Absil, Olivier +9 more
core +3 more sources
, 2014 The limiting magnitude is a key issue for optical interferometry. Pairwise fringe trackers based on the integrated optics concepts used for example in GRAVITY seem limited to about K=10.5 with the 8m Unit Telescopes of the VLTI, and there is a general ...
Benkhaldoum, Zouhair +8 more
core +1 more source
Shack-Hartmann wavefront sensing with elongated sodium laser beacons: centroiding versus matched filtering [PDF]
, 2006 We describe modeling and simulation results for the Thirty Meter Telescope on the degradation of sodium laser guide star Shack-Hartmann wavefront sensor measurement accuracy that will occur due to the spatial structure and temporal variations of the ...
Ellerbroek, Brent, Gilles, Luc
core +1 more source
P-REx II. Off-line Performance on VLTI/GRAVITY [PDF]
arXiv, 2021 For sensitive optical interferometry, it is crucial to control the evolution of the optical path difference (OPD) of the wavefront between the individual telescopes of the array. The OPD between a pair of telescopes is induced by differential optical properties such as atmospheric refraction, telescope alignment, etc. This has classically been measured
arxiv
Control and Alignment of Segmented-Mirror Telescopes: Matrices, Modes, and Error Propagation [PDF]
, 2004 Starting from the successful Keck telescope design, we construct and analyze the control matrix for the active control system of the primary mirror of a generalized segmented-mirror telescope, with up to 1000 segments and including an alternative sensor ...
Chanan, Gary +3 more
core +1 more source
Turbulence scale effects and resolution requirements in aero-optics.
Applied Optics, 2021 While optical aberrations caused by atmospheric turbulence have been extensively investigated and well characterized, recent research has identified structural differences in optical phase distortions caused by aircraft-induced, compressible turbulence ...
Edwin Mathews +3 more
semanticscholar +1 more source
A method of estimating time scales of atmospheric piston and its application at DomeC (Antarctica) [PDF]
, 2007 Temporal fluctuations of the atmospheric piston are critical for interferometers as they determine their sensitivity. We characterize an instrumental set-up, termed the piston scope, that aims at measuring the atmospheric time constant, tau0, through the image motion in the focal plane of a Fizeau interferometer.
arxiv +1 more source