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81.
用实验的方法,研究电流并联负反馈对放大器性能的改善,提出电流型、并联型负反馈放大器性能参数的测量方法。 相似文献
82.
A simple model has been developed to describe the Zeeman patterns of far-infrared laser magnetic resonance spectra of the monobromomethyl radical CH2Br observed at 447.3 and 671.1μm. A satisfactory agreement between the experimental spectra of the radical and their simulation with this simple model has been achieved. This approach can be used to gain further information about the structure and the spectrum of this interesting radical. 相似文献
83.
84.
本文给出了对高功率横流CO_2激光器脉冲预电离过程的理论和实验研究.表明了预电离过程中光电离的重要作用.实验结果表明,脉冲预电离可增大高功率横流CO_2.激光器的pd值(p为放电气压、d为放电间隔),增大放电区注入功率密度.对于提高此类型激光器的放电稳定性和输出激光功率是一种技术简单而有效的手段. 相似文献
85.
Jerzy Paczkowski D. C. Neckers 《Journal of polymer science. Part A, Polymer chemistry》1993,31(3):841-846
Several new fluorescence probes useful for following photopolymerization have been characterized. Among these are probes which can be used in rapidly gelling monomer mixtures and for photochemical polymerization initiated by very high laser powers. Systems which can be used with polyolacrylates and either with visible initiators or with UV initiators are reported. © 1993 John Wiley & Sons, Inc. 相似文献
86.
We fabricated high-quality InAlN/GaN heterostructures by metal–organic vapor phase epitaxy (MOVPE). X-ray diffraction measurements revealed that InAlN/GaN heterostructures grown under optimal conditions have flat surfaces and abrupt heterointerfaces. Electron mobility from 1200 to 2000 cm2/V s was obtained at room temperature. To our knowledge, this mobility is the highest ever reported for InAlN/GaN heterostructures. We also investigated the relationship between the Al composition and sheet electron density (Ns) for the first time. Ns increased from 1.0×1012 to 2.7×1013 cm−2 when the Al composition increased from 0.78 to 0.89. 相似文献
87.
We have presented an investigation of the induced focusing in Kerr media of two laser beams, the pump beam and the probe beam,
which could be either Gaussian or elliptic Gaussian or a combination of the two. We have used variational formalism to derive
relevant beam-width equations. Among several important findings, the finding that a very week probe beam can be guided and
focused when power of both beams are well below their individual threshold for self-focusing, is a noteworthy one. It has
been found that induced focusing is not possible for laser beams of any wavelength and beam radius. In case both beams are
elliptic Gaussian, we have shown that when power of both beams is above a certain threshold value then the effective radius
of both beams collapses and collapse distance depends on power. Moreover, it has been found that induced focusing can be employed
to convert a circular Gaussian beam into an elliptic Gaussian beam. 相似文献
88.
We consider the isothermal flow through a cylindrical flat chamber, a model of some particular heat exchanger, for which LDV measurements and a numerical simulation have been performed. Experimental results show the establishment of an important vortex zone, the secondary flow extending all along the chamber radius. This observation leads to an expected significant increase of the fluid mixing. Results issued from the numerical simulation appear to be in close agreement with experimental data. Nevertheless, the k–ε model used here must be improved to obtain a better approach near the vortex centre. To cite this article: S. Petitot et al., C. R. Mecanique 330 (2002) 593–599. 相似文献
89.
全固态多波长飞秒脉冲激光系统 总被引:1,自引:1,他引:0
利用棱镜对引进频谱空间啁啾来补偿飞秒脉冲激光二次谐波产生中的相位失配,提高了倍频效率建立了一套全固态、多波长(1065nm, 532nm,823.1nm, 402nm)飞秒脉冲激光系统自制的Nd:YVO4激光器输出532nm绿光激光,最高平均功率可达5.6W当用2.5W绿光激光泵浦时,从自制的钛宝石激光器及经BBO倍频可分别输出中心波长为823.1nm和402nm,平均功率300mW和73mW,谱宽32.3nm和5.1nm,脉宽22fs和33.3fs、重复率108MHz的近红外和蓝光激光整个系统具有结构紧凑、倍频效率高、运行稳定的特点. 相似文献
90.
The possibilities of controlling the laser beam properties by a deformable mirror introduced into the laser optical cavity
were studied theoretically and experimentally. The experiments were performed under conditions of an industrial high power
transverse flow cw CO2 laser operating with a stable resonator of a folded configuration. A deformable bimorph mirror of a surface profile controlled
by the voltage applied to the mirror electrodes is implemented to the laser system as a back cavity mirror or as a one of
the inner folding mirrors. The near-and far-field characteristics of the laser beam versus the resonator configuration controlled
by the changes of the focal length of the deformable mirror are discussed in the paper. The analysis reveals that the resonator
with an inner deformable mirror is much more sensitive to the mirror curvature variations than the resonator in which the
deformable mirror is used as a back cavity mirror. The presented results show that dynamic and controllable changes in the
resonator properties result in the controlled modification and optimisation of the laser output power and spatial parameters
of the laser radiation. 相似文献