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# Pulsed 1.5-$\mu$m LIDAR for Axial Aircraft Wake Vortex Detection Based on High-Brightness Large-Core Fiber Amplifier

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French Aerosp. Lab., French Aeronaut. & Space Res. Center (ONERA), Palaiseau
(Impact Factor: 2.83). 05/2009; 15(2):441 - 450. DOI: 10.1109/JSTQE.2008.2010463
Source: IEEE Xplore

ABSTRACT

In this paper, we present the development of an axial aircraft wake vortex light detection and ranging (LIDAR) sensor, working in Mie scattering regime, based on pulsed 1.5-mu m high-brightness large-core fiber amplifier. An end-to-end Doppler heterodyne LIDAR simulator is used for the LIDAR design. The simulation includes the observation geometry, the wake vortex velocity image, the scanning pattern, the LIDAR instrument, the wind turbulence outside the vortex, and the signal processing. An innovative high-brightness pulsed 1.5-mum laser source is described, based on a master oscillator power fiber amplifier (MOPFA) architecture with a large-core fiber. The obtained beam quality is excellent ( M 2 = 1.3), and achieved pulsed energy is 120 muJ with a pulse repetition frequency of 12 kHz and a pulse duration of 800 ns. A Doppler heterodyne LIDAR is developed based on this laser source with a high-isolation free-space circulator. The LIDAR includes a real-time display of the wind field. Wind dispersion is postprocessed. Field tests carried out at Orly airport in April 2008 are reported. Axial aircraft wake vortex signatures have been successfully observed and acquired at a range of 1.2 km with axial resolution of 75 m for the first time with fiber laser source.

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• "The wake vortex generated by a large aircraft is very hazardous to aviation safety because it might cause a following aircraft to roll out of control, particularly during the take-off and landing phases [26]. In order to avoid the wake vortex encountering hazard, many efforts have been made in the past decades to find proper approaches to monitor and detect wake vortices , and the existing approaches include Lidar [5] [6] [8] [13], Sodar [7] [30], and radar [1] [2] [12] [22] [24]. Among them, the radar detection is taken as a very potential approach for its long working range and good adaptability to different weather conditions. "
##### Article: Temporal evolution of the RCS of aircraft wake vortices
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ABSTRACT: Knowledge of the radar scattering characteristics is one of the key issues for the development of wake vortex detection technology. This paper studies the temporal evolution of the RCS (radar cross-section) of wake vortices. The RCS–time plot is observed to increase as a whole and step at a certain time. These properties could provide help to the design of wake vortex detection radar and the optimization of radar station layout. The special spiral structures within the wake, together with the Bragg scattering theory, are used to well explain these phenomena, and some representative radar experiments are also included to verify them.
Full-text · Article · Feb 2013 · Aerospace Science and Technology
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• "The development of a pulsed direct UV LIDAR was reported by Schmitt et al. et al. (2007) for axial detection of wind in the air and for wake vortex detection. Other types of LIDAR were also used, such as 1.5 µm fiber pulse Axial LIDAR (Bouteyre et al., 2009), a 2 µm pulsed infrared airborne LIDAR (Douxchamps et al., 2008), and fiber pulsed axial LIDAR(Akbulut et al., 2011). A commercial wind SODAR was used by Mackey and Burnham (2006). "
##### Conference Paper: Survey for methods of detecting aircraft vortices
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ABSTRACT: Wake vortices produced by the lifting surfaces of large aircraft can have catastrophic effects on aircraft that follow too close behind Many incidents have been blamed on wingtip vortices in the past several decades. Therefore, vortex detection is important for enhancing airport productivity by allowing adoptive spacing and for increasing the safety of all aircraft operating around the airport by alerting controllers that hazardous conditions may exist near the runways. Many methods have been developed for detecting wake vortices. However, there is a lack of a literature review to summarize all the methods and compare their advantages and drawbacks. Thus, the purpose of this paper is to review these technologies and to summarize their strengths and weaknesses. There are two main methods available in the literature: active and passive detection methods. Active detection methods include LIDAR (LIGHT Detection And Ranging), RADAR (Radio Detection and Ranging), and SODAR (Sonic Detection And Ranging). Passive detection methods include microphone systems, opto-acoustic systems, and ultrasonic detection of circulation. Although vortex detection methods are available, due to military and scientific usage, many researchers are still investigating new methods that are more effective.
Full-text · Conference Paper · Jan 2012
• ##### Article: Semianalytic pulsed coherent laser radar equation for coaxial and apertured systems using nearest Gaussian approximation
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ABSTRACT: We present a semianalytic pulsed coherent laser radar (CLR) equation for coaxial and apertured systems. It combines the conventional CLR equation, numerical Fresnel integration (NFI), and nearest Gaussian approximation, using correction factors that correspond to beam truncation. The range dependence of the signal-to-noise ratio obtained by this semianalytic equation was found to agree well with the precise NFI solution for not only the focal range, but also the near-field range. Furthermore, the optimum beam truncation condition depending on the atmospheric refractive index structure constant is shown. The derived equation is useful for precisely predicting the CLR performance simply by its semianalytic expression.
No preview · Article · Sep 2010 · Applied Optics