نتایج جستجو برای: remote sensing by laser beam

تعداد نتایج: 7282589  

پایان نامه :وزارت علوم، تحقیقات و فناوری - دانشگاه شیراز - دانشکده علوم 1390

any change in the refractive index of a laser active medium can lead to serious degradation of beam quality, laser beam modes, laser performance and variation in the intensity distribution. alteration in the refractive index of laser active medium is especially notable in high power lasers. it is clear that in the laser beam production, the pumping agent induces a great amount of heat which...

N. Nithya, R. Mahalakshmi, S. Sagadevan,

The study of amino acid based nonlinear optical (NLO) materials with optimum physical properties is an important area due to their practical applications such as optical communication, optical computing, optical information processing, optical disk data storage, laser fusion reactions, laser remote sensing, colour display, medical diagnostics, etc. Also, microelectronic industries require cryst...

Journal: :Optics express 2009
Benjamin G Lee Jan Kansky Anish K Goyal Christian Pflügl Laurent Diehl Mikhail A Belkin Antonio Sanchez Federico A Capasso

Wavelength beam combining was used to co-propagate beams from 28 elements in an array of distributed-feedback quantum cascade lasers (DFB-QCLs). The beam-quality product of the array, defined as the product of near-field spot size and far-field divergence for the entire array, was improved by a factor of 21 by using wavelength beam combining. To demonstrate the applicability of wavelength beam ...

2003
John S. Popovics

John S. Popovics Summary Lasers are devices that create a high intensity, directed light beam. The light beam can travel in air or through fiber optic cables. Lasers can be used to generate waves and detect stretching or motion in a solid material without direct contact with the material. Thus lasers are useful in many important engineering applications that require remote non-destructive evalu...

Journal: :The Review of scientific instruments 2014
Young-Keun Kim In Gwun Jang Kyung-Soo Kim Soohyun Kim

This paper presents performance enhancement of the three beam detector through design improvement based on the error analysis. The three-beam detector is a novel sensor system that measures six motions (i.e., 3 translations and 3 rotations) of a remote object with high accuracy by implementing three laser distance sensors and a vision sensor. In this paper, finite element analysis and parameter...

پایان نامه :وزارت علوم، تحقیقات و فناوری - دانشگاه زنجان 1387

چکیده ندارد.

Journal: :Remote Sensing 2013
Ola Ringdahl Peter Hohnloser Thomas Hellström Johan Holmgren Ola Lindroos

Accurate vehicle localization in forest environments is still an unresolved problem. Global navigation satellite systems (GNSS) have well known limitations in dense forest, and have to be combined with for instance laser based SLAM algorithms to provide satisfying accuracy. Such algorithms typically require accurate detection of trees, and estimation of tree center locations in laser data. Both...

2012
S. I. Mitryukovskiy Y. Liu A. Houard

Laser filaments appear spontaneously during the propagation of intense ultrashort laser pulses with a power exceeding a critical value Pcr (Pcr = 5 GW at 800 nm in air) [1]. The intense beam tends to collapse due to the optical Kerr self-focusing effect until the intensity is high enough to ionize the medium, giving rise to a defocusing plasma. Thereafter, a dynamic competition between these tw...

Journal: :Optics letters 2004
Gadi Fibich Shmuel Eisenmann Boaz Ilan Arie Zigler

In this Letter we provide what is believed to be the first experimental evidence of suppression of the number of filaments for high-intensity laser pulses propagating in air by beam astigmatism. We also show that the number, pattern, and spatial stability of the filaments can be controlled by varying the angle that a focusing lens makes with the axial direction of propagation. This new methodol...

2015
Fei Wang Xianlong Liu Yangjian Cai

Partially coherent beam is preferred in many applications, such as free-space optical communications, remote sensing, active laser radar systems, etc., due to its resistance to the deleterious effects of atmospheric turbulence. In this paper, after presenting a historical overview on propagation of optical beams in turbulent atmosphere, we describe the basic theory for treating the propagation ...

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