412 resultados para Bai f, Lazare de, 1496?-1547.
Resumo:
Far-field spot compression without energy loss in main lob is of great significance to wireless laser communication. In this letter, we propose two schemes to obtain far-field spot compression without energy loss in main lob. One scheme is based on the simulated annealing (SA) algorithm. Using SA algorithm, we design the phase profile of the diffractive phase element (DPE). Using the designed DPE, far-field spot compression without energy loss in main lob is achieved. The other scheme is based on YG algorithm. By means of YG algorithm, we appropriately designed the DPE in the emitting plane. Using the DPE, far-field spot compression without energy loss in main lob is obtained. (c) 2007 Elsevier GmbH. All rights reserved.
Resumo:
Doubled femtosecond laser pulses in-line are needed in the collinear pump-probe technique, collinear second harmonic generation frequency-resolved optical gating (SHG FROG) and the spectral phase interferometry for direct electric-field reconstruction (SPIDER), etc. Normally, it is generated by using a Michelson's structure. In this paper, we proposed a novel structure with two-layered reflective Dammann gratings and the reflective mirrors to generate doubled femtosecond laser pulses in line without transmission optical elements. Angular dispersion and spectral spatial walk-off are both compensated. In addition, this structure can also compress the positive chirped pulse, which cannot be realized with a Michelson's structure. By adopting triangular grating and blazed gratings, the efficiency of the system would in principle be increased as the Michelson's scheme. Experiments demonstrated that this method should be an alternative approach for generation of the double compressed pulses of femtosecond laser for practical applications. (c) 2006 Elsevier GmbH. All rights reserved.
Resumo:
The Er3+-Yb3+ codoped Al2O3 has been prepared by the sol-gel method using the aluminium isopropoxide [Al(OC3H7)(3)]-derived Al2O3 sols with addition of the erbium nitrate [Er(NO3)(3) center dot 5H(2)O] and ytterbium nitrate [Yb(NO3)(3) center dot 5H(2)O]. The phase structure, including only two crystalline types of doped Al2O3 phases, theta and gamma, was obtained for the 1 mol% Er3+ and 5 mol% Yb3+ codoped Al2O3 at the sintering temperature of 1,273 K. By a 978 nm semiconductor laser diodes excitation, the visible up-conversion emissions centered at about 523, 545, and 660 nm were obtained. The temperature dependence of the green up-conversion emissions was studied over a wide temperature range of 300-825 K, and the reasonable agreement between the calculated temperature by the fluorescence intensity ratio (FIR) theory and the measured temperature proved that Er3+-Yb3+ codoped Al2O3 plays an important role in the application of high temperature sensor.
Resumo:
We demonstrate, for the first time as far as Re known, a passively Q-switched operation of a Nd:YVO4 laser in which a Cr4+:YAG crystal and a laser-diode bar are used as the saturable absorber and the pump source, respectively. Stable laser pulses as short as 28 ns with 20-mu J energy can be generated with this laser, which has the advantages of simplicity, high efficiency, and good long-term stability. (C) 1997 Optical Society of America.
Mating patterns and pollen dispersal in a heterodichogamous tree, Juglans mandshurica (Juglandaceae)
Resumo:
SyringaOleaceae -------- 3612).3),4 5).6Ser. Villosae (Schneid.) Rehd. 1Ser. Syringa2-4Ser, Pinnatifolia Rehd,5Sect.Ligustrina Rupr.6 n=2324n=lln=12n 2n=24 221Syringa protolaciniataSx persica Sx laciniataSafghanica Ser. Pinnatifolia2Set. VulgaresSer. PubescentesSer. Syringa3Syringa potaninii Schneid.Smicropylla Dielsspatula (Palibin) NakaiSjuliana Schneid.Sdilatata NakaiSyunanensis Franch.fpubicalyx (Jien ex P.Y. Bai) M.C. Chang232 1Sect.l. Syringa:1Ser.1Villosae(Sch- neid.)Rehd.;2Ser.2. Syringa1Subser.1Syring2Pubescentes(Schneid.)Rehd.;3Ser.3. Pinnatifoliae Rehd. 2Sect.2. Ligustrina Rupr. Sect. Sarcocarpion (Franch.)Mansf. 28592111
Resumo:
61199216;Flora of China1519961620 16200070124050061940;;; 22121313;5565;12134S. pubescens MeyerS. villosa subsp. wolfiiS. yunnanensis subsp. sweginzowiiS. yunnanensis subsp. tomentella11S. fauriei H. Lv.S. julianae C. K. Schneid.S. meyeri var. spontanea M. C. ChangS. pinetorum W. W. Sm.S. wardii W. W. Sm.S. oblata var. donaldii R. B. Clark et J. L. FialaS. afghanica C. K. Schneid.S. protolaciniata P. S. Green et M. C. ChangS. tibetica P. Y. BaiS. reflexa C. K. Schneid. S. wilsonii C. K. Schneid.34(S. reticulata subsp. reticulata S. reticulata subsp. amurensisS. pubescens subsp. microphyllaS. oblata subsp. dilatata10 13162n=482n=46
