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By seeding amplifying plasmas pumped with the so-called Transient collisionnal excitation scheme, the amplified pulse seems to be limited to an energy of several 10's of J. Aiming to attain several mJ, we study the seeding of plasma pumped by long laser pulse. Thanks to our time-dependant Maxwell-Bloch code, we demonstrate that direct seeding with femtosecond pulse is inefficient. We also study the amplification of pulse train with the drawback of re-synchronizing the pulses. We proposed and studied the amplification of high harmonic seed stretched by a grating pair, amplified finally compressed. We consider off-axis diffraction on the gratings for maximizing their efficiency. Considering the phase deformation induced by the amplification and the spectral narrowing the final pulse is 230 fs in duration and 5 mJ.

Animals for surviving have developed cognitive abilities allowing them an abstract representation of the environment. This Internal Representation (IR) could contain a huge amount of information concerning the evolution and interactions of the elements in their surroundings. The complexity of this information should be enough to ensure the maximum fidelity in the representation of those aspects of the environment critical for the agent, but not so high to prevent the management of the IR in terms of neural processes, i.e. storing, retrieving, etc. One of the most subtle points is the inclusion of temporal information, necessary in IRs of dynamic environments. This temporal information basically introduces the environmental information for each moment, so the information required to generate the IR would eventually be increased dramatically. The inclusion of this temporal information in biological neural processes remains an open question. In this work we propose a new IR, the Compact Internal Representation (CIR), based on the compaction of spatiotemporal information into only space, leading to a stable structure (with no temporal dimension) suitable to be the base for complex cognitive processes, as memory or learning. The Compact Internal Representation is especially appropriate for be implemented in autonomous robots because it provides global strategies for the interaction with real environments (roving robots, manipulators, etc.). This paper presents the mathematical basis of CIR hardware implementation in the context of navigation in dynamic environments. The aim of such implementation is the obtaining of free-collision trajectories under the requirements of an optimal performance by means of a fast and accurate process.

Many scene change detection techniques have been developed for scene cuts, fade in and fade out by analyzing video encoder input signals. For real time scene change detection, sensor input signals provide first-hand information which can be used for scene change detection. In this paper, by analyzing camcorder front end sensor input signals with our proposed algorithms based on camera 3A (auto exposure, auto white balance and auto focus), a novel scene change detection technique is described. Camera 3A based scene change detection algorithm can detect scene changes in a timely manner and therefore fits well for real time scene change detection applications. Experimental results show that this algorithm can detect scene changes with good accuracy. The proposed algorithm is computationally efficient and easy to implement.

Seeding plasma-based soft-x-ray lasers (PBSXR) with high order harmonics (HOH) is a promising way to obtain fully coherent, short (hundreds of femtoseconds), tens of microJoules pulses. Nevertheless, up to date only 1 J, 1 ps pulses have been demonstrated seeding plasmas created from gas targets and solid targets. As the amplification process couples plasma hydrodynamics, atomic processes and the propagation of electromagnetic fields, a careful optimization of seed and amplifier properties is essential to reach multi-microJoule, hundreds of fs regime. Recent papers showed that short and wide (up to 1 mm) plasmas present an optimal gain zone and up to 20 J could be extracted when seeding. Nevertheless, the temporal duration and profile of the output beam is still not optimal. Simulations show that the HOH is weakly amplified whereas most of the energy is within a long (several picoseconds) wake induced by the HOH. In addition to this, these simulation pointed out the presence of deleterious Amplified Spontaneous Emission (ASE). In order to obtain intense pulses useful for practical applications is crucial to reduce the duration to hundreds of fs and obtain ASE-suppressed, structure-free (ideally only an amplified HOH) pulses. Using the 1D Bloch-Maxwell code DeepOne we will show that fully coherent, wake and ASE-suppressed, 15 J, 120 fs pulse can be obtained when optimizing at the same time both the seed and the plasma conditions.

Seeding plasma-based soft x-ray laser (SXRL) demonstrated diffraction-limited, fully coherent in space and in time beam but with energy not exceeding 1 J per pulse. Quasi-steady-state (QSS) plasmas demonstrated to be able to store high amount of energy and then amplify incoherent SXRL up to several mJ. Using 1D time-dependant Bloch-Maxwell model including amplification of noise, we demonstrated that femtosecond HHG cannot be efficiently amplified in QSS plasmas. However, using Chirped Pulse Amplification concept on HHG seed allows to extract most of the stored energy, reaching up to 5 mJ in fully coherent 130 fs pulses. Original pump-probe experiments will be proposed thanks to the high laser energy available in ELI facilities.