English
Related papers

Related papers: Laser guide star return-flux gain from frequency c…

200 papers

We present a study of the low-frequency radio properties of star forming (SF) galaxies and active galactic nuclei (AGN) up to redshift $z=2.5$. The new spectral window probed by the Low Frequency Array (LOFAR) allows us to reconstruct the…

Single-shot ultrafast absorbance spectroscopy based on the frequency encoding of the kinetics is analyzed theoretically and implemented experimentally. The kinetics are sampled in the frequency domain using linearly chirped, amplified 33 fs…

Spectral-line results from a new cryogenic phased array feed (cryoPAF) on the Murriyang telescope at Parkes are presented. This array offers a significant improvement in field of view, aperture efficiency, bandwidth, chromaticity and survey…

The Max-Planck institutes for astronomy (MPIA) and for extraterrestrial physics (MPE) run an adaptive optics (AO) system with a laser guide star at the 3.5 m telescope on Calar Alto, Spain. This system, called ALFA, produces now scientific…

Instrumentation and Methods for Astrophysics · Physics 2016-07-20 Markus Kasper , Douglas Looze , Stefan Hippler , Ric Davies , Andreas Glindemann

In this study, the frequency of an external cavity diode laser with an antireflection-coated laser diode was continuously tuned over a range of 14.8 GHz, which was 4.5 times larger than the free spectral range, by only sweeping the…

Optics · Physics 2024-12-17 Akifumi Takamizawa

The High Resolution Camera (HRCam) speckle imager at the 4.1 m Southern Astrophysical Research telescope is a highly productive instrument that has accumulated about 40K observations to date. Its performance (detected flux, level of the…

Instrumentation and Methods for Astrophysics · Physics 2024-08-23 Andrei Tokovinin

Many experiments in biological and medical sciences currently use multiphoton microscopy as a core imaging technique. To date, solid-state lasers are most commonly used as excitation beam sources. However, the most demanding applications…

For exploring the application potential of coherent soft x-ray (SXR) and extreme ultraviolet radiation (XUV) provided by high-harmonic generation, it is important to characterize the central output parameters. Of specific importance are…

Aims. We study the 2D spectral line profile of HARPS (High Accuracy Radial Velocity Planet Searcher), measuring its variation with position across the detector and with changing line intensity. The characterization of the line profile and…

A key for understanding the evolution of galaxies and in particular their star formation history will be future ultra-deep radio surveys. While star formation rates (SFRs) are regularly estimated with phenomenological formulas based on the…

Astrophysics of Galaxies · Physics 2017-04-12 Jennifer Schober , Dominik R. G. Schleicher , Ralf S. Klessen

Detecting and studying pulsars above a few GHz in the radio band is challenging due to the typical faintness of pulsar radio emission, their steep spectra, and the lack of observatories with sufficient sensitivity operating at high…

High Energy Astrophysical Phenomena · Physics 2018-06-29 Pablo Torne

Generation of high-fidelity amplified pulse bursts with a regular interpulse interval yields, in the spectral domain, an equidistant pattern of narrowband spectral modes, similar to frequency combs produced by cw mode-locked lasers, but…

Intrinsic spectrum that results from the coupling of spontaneous emission in a laser cavity, can determine the energy concentration and coherence of lasers, which is crucial for the optical high-precision measurement. Up to now, it is hard…

When bright solar-system objects are observed by GHz-THz regime telescopes, off-axis signals bounce around locally and re-enter the signal path with a time delay, causing sinusoidal ripples in output spectra. Ripples that are unstable over…

Earth and Planetary Astrophysics · Physics 2024-11-07 J S Greaves

The radio continuum spectra of 14 star-forming galaxies are investigated by fitting nonthermal (synchrotron) and thermal (free-free) radiation laws. The underlying radio continuum measurements cover a frequency range of ~325 MHz to 24.5 GHz…

Astrophysics of Galaxies · Physics 2018-03-28 Uli Klein , Ute Lisenfeld , Simon Verley

Solar flares may be the best-known examples of the explosive conversion of magnetic energy into bulk motion, plasma heating, and particle acceleration via magnetic reconnection. The energy source for all flares is the highly sheared…

Solar and Stellar Astrophysics · Physics 2022-08-02 Joel T. Dahlin , Spiro K. Antiochos , Jiong Qiu , C. Richard DeVore

Laser guide stars created by Rayleigh scattering provide a reasonable means to monitor atmospheric wavefront distortions for real-time correction by adaptive optics systems. Because of the $\lambda^{-4}$ wavelength dependence of Rayleigh…

Astrophysics · Physics 2007-05-23 L. A. Thompson , S. W. Teare

We describe a method for the determination of stellar [C/Fe] abundance ratios using low-resolution (R = 2000) stellar spectra from the SDSS and SEGUE. By means of a star-by-star comparison with a set of SDSS/SEGUE spectra with available…

The performance of adaptive optics systems is partially dependant on the algorithms used within the real-time control system to compute wavefront slope measurements. We demonstrate use of a matched filter algorithm for the processing of…

By measuring the thermal effects resulting from stimulated Raman excitations, stimulated Raman photothermal (SRP) microscope offers a new access to spatially and temporally resolved Raman signatures across various sample types. Unlike…

Optics · Physics 2026-03-03 Yifan Zhu , Hongli Ni , Hongjian He , Yueming Li , Meng Zhang , Ji-Xin Cheng