The work presented here experimentally measures the tilt imposed on a laser beam by the atmosphere from Shack-Hartmann wavefront sensor measurements collected in-flight. Tip/tilt is imposed on the laser beam by propagating through optical turbulent structures larger than or of the order of the size of the beam diameter. This tip/tilt causes a dynamic, net deflection of the beam in the far field, referred to as jitter, which poses a serious problem for tracking in directed energy applications. The practical measurement of turbulence-induced tip/tilt at altitude is challenging since mechanical contamination in the form of vibrations also manifests as tip/tilt. In this paper, a procedure referred to as the stitching method is used to quantify the turbulence-induced component of tilt without the influence of mechanical corruption. It is found that the measured tilt aligns with what analytic solutions predict and that the turbulent environment through which the beam propagates has Kolmogorov-like characteristics.
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http://dx.doi.org/10.1364/AO.460717 | DOI Listing |
Materials (Basel)
December 2024
Applied Materials Science, Uppsala University, SE-751 03 Uppsala, Sweden.
In additive manufacturing, the presence of residual stresses in produced parts is a well-recognized phenomenon. These residual stresses not only elevate the risk of crack formation but also impose limitations on in-service performance. Moreover, it can distort printed parts if released, or in the worst case even cause a build to fail due to collision with the powder scraper.
View Article and Find Full Text PDFPhys Rev Lett
December 2024
Departamento de Física e Astronomia, Faculdade de Ciências, Universidade do Porto, Rua do Campo Alegre s/n, 4169-007 Porto, Portugal and INESC TEC, Centre of Applied Photonics, Rua do Campo Alegre 687, 4169-007 Porto, Portugal.
Easily accessible through tabletop experiments, paraxial fluids of light are emerging as promising platforms for the simulation and exploration of quantumlike phenomena. In particular, the analogy builds on a formal equivalence between the governing model for a Bose-Einstein condensate under the mean-field approximation and the model of laser propagation inside nonlinear optical media under the paraxial approximation. Yet, the fact that the role of time is played by the propagation distance in the analog system imposes strong bounds on the range of accessible phenomena due to the limited length of the nonlinear medium.
View Article and Find Full Text PDFRev Sci Instrum
December 2024
State Key Laboratory of Particle Detection and Electronics, University of Science and Technology of China, No. 96, Jinzhai Road, Hefei, Anhui, China.
We present a fully digital servo optimized for ultra-stable laser frequency stabilization. Experiments such as optical clock experiments can achieve high laser frequency stability, imposing high bandwidth, high precision, and low noise requirements on servo systems. The laser system utilizes the Pound-Drever-Hall method, employing an ultra-stable cavity to generate an error signal for servo input.
View Article and Find Full Text PDFSensors (Basel)
November 2024
Center for Gravitational Wave Experiment, National Microgravity Laboratory, Institute of Mechanics, Chinese Academy of Sciences, Beijing 100190, China.
Since Einstein's prediction regarding the existence of gravitational waves was directly verified by the ground-based detector Advanced LIGO, research on gravitational wave detection has garnered increasing attention. To overcome limitations imposed by ground vibrations and interference at arm's length, a space-based gravitational wave detection initiative was proposed, which focuses on analyzing a large number of waves within the frequency range below 1 Hz. Due to the weak signal intensity, the TMs must move along their geodesic orbit with a residual acceleration less than 10 m/s/Hz.
View Article and Find Full Text PDFJ Phys Chem B
December 2024
Institute of Electronic Structure and Laser, FORTH, Heraklion 70013, Greece.
The response of soft materials to an imposed oscillatory stress is typically frequency dependent, with the most utilized frequency range falling in the range of 10-10 rad/s. In contrast to most conventional contact techniques for measuring material elasticity, like tensile or shear rheology and atomic force microscopy, or invasive techniques using probes, such as microrheology, Brillouin light spectroscopy (BLS) offers an optical, noncontact, label-free, submicron resolution and three-dimensional (3D) mapping approach to access the mechanical moduli at GHz frequencies. Currently, the correlation between the experimental viscoelastic (at lower frequencies) and elastic (at higher frequencies) moduli has fundamental and practical relevance, but remains unclear.
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