Changing debris orbits using High Power Pulsed Laser Interaction (HP PLI) finds interest in the Low-Earth Orbit (LEO) due to space debris congestion. Laser facilities allowing both high energy and repetition rate of a short pulsed irradiation become available as provided by the high power HiLASE beamline facility (Prague, CZ) with BIVOJ (100J, 10ns, 10Hz, 1030nm). In order to illustrate such an application, originally Crookes radiometer concept was adapted to quantify the efficiency of repeated laser shots in increasing rotating speed according to laser matter interaction. Various materials, from model to space applicative materials, allowed to estimate the material response with various irradiation characteristics (single shots vs. repeated shots). Matter behaviors (ablation, cratering, spallation, perforation) bracketed the laser conditions suitable in the perspective of laser propulsion with limited creation of extra debris or irradiated structures damages. Next is to strengthen the robustness of the simulation/experiment dialog to use simulation as a predesign tool for laser space propulsion.
We report on the successful commissioning of DiPOLE-100Hz, a DPSSL amplifying nanosecond pulses to 10 J energy at 100 Hz repetition rate. As part of initial commissioning experiments, the system was configured to amplify 15 ns pulses at 100 Hz pulse rate to an energy of 7 J. The system was operated at this level for four hours (corresponding to 1.44·106 shots) with an energy stability of 1% rms. Subsequently, the laser demonstrated amplification of 15 ns pulses to the full specification of 10 J, 100 Hz, corresponding to 1 kW average power, with an optical-to-optical efficiency of 25.4% and long-term energy stability of less than 1% rms measured over one hour. To the best of our knowledge, this is the first time long-term, reliable operation of a kW-class high energy nanosecond pulsed DPSSL at 100 Hz has been demonstrated.
Laser beam distribution system (LBDS) is an important component at any high-power laser facility. Being a system of mirrors, lenses, and windows, the LBDS can significantly contribute to the laser beam quality degradation at target location. Phase correcting methods are among the few instruments allowing efficient control over the laser spot quality at the application site. We present a simpler solution utilizing only a PSF camera at every site. The PSF optimization is a sensorless modal correction algorithm, where each Legendre polynomial is scanned by the deformable mirror to find the best shape that maximize the PSF sharpness metric.
Laser amplifiers producing high energy (multi-J) nanosecond pulses at high repetition rate (multi-Hz) are required for a wide range of commercial and scientific applications. The DiPOLE concept, developed at the STFC Central Laser Facility (UK), consists in scalable, high-energy DPSSL amplifiers based on cryogenically-cooled, multi-slab ceramic Yb:YAG. In this work we discuss the most recent developments aimed at scaling the pulse repetition of new generation DiPOLE lasers from 10 Hz to 100 Hz. We present the design and current status of a 10 J, 100 Hz DiPOLE laser. We will discuss thermal management approaches adopted for this system.
Spectrum of light which is emitted or reflected by an object carries immense amount of information about the object. A simple piece of evidence is the importance of color sensing for human vision. Combining an image acquisition with efficient measurement of light spectra for each detected pixel is therefore one of the important issues in imaging, referred as hyperspectral imaging. We demonstrate a construction of a compact and robust hyperspectral camera for the visible and near-IR spectral region. The camera was designed vastly based on off-shelf optics, yet an extensive optimization and addition of three customized parts enabled construction of the camera featuring a low f-number (F/3.9) and fully concentric optics. We employ a novel approach of compressed sensing (namely coded aperture snapshot spectral imaging, abbrev. CASSI). The compressed sensing enables to computationally extract an encoded hyperspectral information from a single camera exposition. Owing to the technique the camera lacks any moving or scanning part, while it can record the full image and spectral information in a single snapshot. Moreover, unlike the commonly used compressed sensing table-top apparatuses, the camera represents a portable device able to work outside a lab. We demonstrate the spectro-temporal reconstruction of recorded scenes based on 90×90 random matrix encoding. Finally, we discuss potential of the compressed sensing in hyperspectral camera.
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