反映当代高技术──激光生物学的专著《激光生物学》出版

反映当代高技术──激光生物学的专著《激光生物学》出版由青年学者向阳编著，由湖南科学技术出版社沙一飞编辑的《激光生物学》一书，最近已由湖南科学技术出版社出版。这是一本反映当代高技术─—激光生物学的专著，同时也是我国第一本以激光生物学学科命名的专著。激光...     

材料生物学——骨修复材料的机遇与挑战

材料与宿主微环境之间的相互作用直接影响骨修复的过程和质量。由于对材料在体内微环境中的生物学效应、修复过程及作用机理不清楚,导致目前大部分材料的修复效果不理想,难以达到真正的"骨性融合",临床应用受限。因此,弄清材料在骨修复过程中的生物学效应及其发生规律迫在眉睫。综述了骨修复材料在植入体内后产生的免疫调控效应、与体内生长因子的协同效应、以及血管化效应等一些新的生物学效应,指出了材料在体内所处的环境并非静止的,而是动态变化的,材料参数改变体内微环境,进而影响再生过程;同时,微环境也影响了材料的转归命运。聚焦材料生物学研究,揭示材料在生命活动中的作用机制和规律,将是未来组织修复材料的发展趋势。     

靶蒸气等离子体对高功率激光的反射效应

置于真空靶室中的金属靶 ( Fe) ,在高功率激光作用下产生的高密度等离子体 ,对入射激光有较强的受激布里渊散射效应。这种逆着入射激光方向的散射光 ,在5× 1 0 1 1 W/cm2 的激光功率密度作用下 ,后向散射能量是 0 .1 6 J。这种后向散射光 (反射 ) ,在激光器系统不加光学隔离的情况下 ,又反馈回来 ,使激光器某单元形成激光振荡 ,在激光器高功率单脉冲输出之后 ,又产生很强的自由振荡激光输出 ,使激光力学效应物理实验出现导常现象     

实际大气中激光闪烁效应的实验观测

就实际大气中激光闪烁效应的观测实验系统及实验结果，分析了背景与探测器件本身噪声以及探测器件饱和效应对实验结果精度的影响。     

单粒子效应激光模拟试验技术研究

介绍了一种新的单粒子效应模拟试验技术——脉冲激光模拟试验方法。对脉冲激光束进行单粒子效应试验研究的基本机理进行了分析讨论。总结分析了电子器件及集成电路单粒子效应激光模拟试验研究结果,给出了单粒子效应脉冲激光模拟试验的一般评估方法,并对采用脉冲激光模拟单粒子翻转试验获得的试验数据与重离子试验数据的等效性进行了比对分析。结果表明,激光模拟试验得出的LET阈值大小与重离子试验结果基本一致。     

紫外光纤的激光传输特性测试

为适应紫外激光传输需要，试制了高透过紫外石英光纤，设计了实验装置，并测量了该种光纤的紫外传输损耗、弯曲损耗、激光损伤阈值和非线性光学效应，并与普通商用石英光纤作比较。分析并获得了紫外光纤的激光传输特性。     

校正激光直写邻近效应的快速方法

针对激光直写中的邻近效应的特点，提出通过直写曝光数据补偿进行光学邻近效应校正的快速，有效方法，并获得了满意的实验结果。     

单粒子效应的激光模拟方法研究进展

单粒子效应是一种会引起器件状态改变的辐射效应现象,会对器件性能、状态造成重大影响,甚至可能造成器件无法正常工作.本文介绍了目前各种单粒子效应的研究方法,重点综述了脉冲激光模拟研究的进展,汇总了近些年来国内外的代表性研究机构以及相应的测试装置参数,同时对脉冲激光诱导产生单粒子效应的机理、研究测试方法和代表性前沿器件研究的成果进行了概括,最后对脉冲激光模拟单粒子效应的方法、器件的研究方向等进行展望.     

激光分离铀同位素分离器的设计及应用

描述了用ＤＭＰ－４５０型镀膜机改造，设计成应用于激光铀同位素分离的分离器装置。选用６０００Ｗ电子枪作为加热泊，产生激光同位素分离实验所需的铀蒸气，对激光与铀原子相互作用区中的铀原子密度进行了估算。讨论了在蒸发中，由多普勒效应引起的谱线加宽衣热离子等对分离实验的影响因素和排除方法。还对高温下液态铀的强腐蚀性，加热坩埚和屏蔽罩的实验选择等方面进行了有益的探讨。     

激光自混频干涉法测量表面粗糙度的理论分析

设计了一种半导体激光自混频干涉法测量表面粗糙度的实验，对半导体激光自混频干涉法测量表面粗糙度中的干涉效应进行了理论分析，推导了干涉信号与表面粗糙度的数学关系式，讨论了影响测量信号的因素。实验结果表明，随着加工表面粗糙度的降低，反射光的强度逐渐增加，被测物体表面的反射率越高，越有利于测量。     

Photon-drag effect in single-walled carbon nanotube films

We observed an interaction of single-walled carbon nanotube films with obliquely incident nanosecond laser radiation in visible and infrared regions generating unipolar voltage pulses replicating the shape of the laser pulses. The photoelectric signal significantly depends on the laser polarization and has maximum value at the laser beam incidence angle of ±65° and at the film thickness of 350 nm. The results are explained in the framework of the photon-drag effect.     

The optical attenuation of laser radiation in thin fullerene C70-polyimide films. Effect of fullerenes on the transmission of azide films

The phenomenon of optical attenuation of laser radiation in the visible spectral range was studied in a promising photosensitive medium based on fullerene C₇₀-polyimide films. The effect of fullerenes on the transmission of laser radiation in azide-based systems is demonstrated.     

Correlations between visible light scattering and CO2 laser damage to reflective and antireflective coatings

In this work, 10.6-microm pulsed laser damage studies were performed on reflective and antireflective coatings on Si, Ge, and ZnSe substrates. Single-pulse damage threshold determinations were conducted at two different laser spot sizes. A high-resolution TV system was used to perform visible light scattering studies, the results of which correlated with laser damage at 10.6 microm. Single-pulse damage determinations along with visible light scattering and multipulse damage determinations indicate that coating performance can be improved substantially by reducing the density of scattering centers present on the coatings.     

Strong quantum confinement effects in polymer-based PbS nanostructures prepared by ion-exchange method

Nanostructures of narrow band-gap semiconductiors such as PbS provide a large scope for band-gap engineering as strong quantum confinement effects can alter the bulk band-gap value all the way from 0.41 to 2.3 eV, rendering the material transparent in most of the visible range of the electromagnetic spectrum. This paper discusses the preparation and characterization of polymer-based PbS nanostructures showing large characteristic blue shift in optical absorption. Enhancement in electrical resistivity is observed as a result of quantum confinement. This material is found to exhibit strong thermal lens effects, which is utilized to achieve optical limiting at low laser power levels.     

Femtosecond laser assisted hatching: Dependence of <Emphasis Type="Italic">zona pellucida</Emphasis> drilling efficiency and embryo development on laser wavelength and pulse energy

Ultrashort laser pulses have enabled highly precise and delicate processing of biological specimens. We present the results of using femtosecond laser pulses for dissection of zona pellucida (ZP) in mouse embryos during assisted hatching procedure. We studied the effects of application of femtosecond laser radiation in the infrared (1028 nm) and visible (514 nm) wavelength ranges. Laser irradiation parameters were optimized so as not to compromise the viability of the treated embryos. We have demonstrated that application of femtosecond laser pulses with the energies in the range of 250–320 nJ (for the wavelength of 1028 nm) and 47–112 nJ (for 514 nm) resulted in efficient ZP dissection. Femtosecond laser-assisted ZP drilling does not slow down the development of pre-implantation embryos and leads to 90–95% frequency of complete hatching. The thermal effects can be significantly lower when femtosecond lasers are used as compared to continuous wave or long-pulse lasers. It is crucial when dealing with living cells or organisms. By optimizing femtosecond laser radiation parameters assisted hatching as well as a wide range of embryo-surgical procedures can be efficiently performed, thus creating a great potential of using femtosecond lasers as a multi-purpose “tool of choice” for specialists in the fields of embryology and developmental biology.     

Generation of multifrequency laser emission quasi equally spaced throughout the entire visible region

A circularly polarized, monochromatic laser beam is focused into a Raman cell, which contains hydrogen to generate rotational stimulated Raman emission. After linear polarization, this two-color (separated by 587 cm(-1)) laser beam is focused several times into a second Raman cell that is filled with hydrogen to generate a multifrequency laser emission. Many rotational and vibrational lines are generated efficiently by this multipass effect. Eighteen colors that are quasi equally spaced with a rather flat intensity distribution are generated throughout the entire visible region. The present multifrequency laser emission may be advantageously used for illumination in a higher-grade display, such as a laser light show.     

Laser power coupling efficiency in conduction and keyhole welding of austenitic stainless steel

Laser welding of thin sheets of AISI 304 stainless steel was carried out with high power CW CO₂ laser. The laser power utilized in the welding process was estimated using the experimental results and the dimensionless parameter model for laser welding; and also the energy balance equation model. Variation of laser welding efficiency with welding speed and mode of welding was studied. Welding efficiency was high for high-speed conduction welding of thin sheets and also in keyhole welding process at high laser powers. Effect of pre-oxidization of the surface and powder as filler material on laser power coupling is also reported. The paper also discusses effect of microstructure on the cracking susceptibility of laser welds.     

Microstructure and optical characterization of nanometric silicon films prepared by pulsed laser ablation

The effect of laser energy density, during pulsed laser ablation, on the microstructure and optical properties of silicon films has been investigated using techniques such as atomic force microscopy, scanning electron microscopy, X-ray diffraction, and UV–visible absorption/transmission spectroscopy. The thickness of prepared films increases with increase in laser energy density. The crystallite size and hence the crystallinity of prepared films have been estimated by X-ray diffraction and found to be dependent on laser energy density. The transmittance of films changes with laser energy density. The absorption coefficient of films has been found to be?>10⁴?cm^?1 in wavelength region 450–1100?nm. The band gap of silicon films has been determined as 2.27, 2.11, and 1.90?eV corresponding to laser energy density of 1.5, 2.5, and 3.5?J?cm^?2, respectively.     

可见光波段稀土激光晶体的研究进展

可见光激光在数据存储、光通讯、激光显示、激光医疗、激光打印以及科学研究等领域具有非常重要的应用价值。随着蓝光LD泵浦源的商用化, 直接泵浦稀土离子掺杂激光晶体实现可见光激光输出吸引了人们极大的研究兴趣。目前, 可见光稀土离子主要集中在Pr ³⁺、Dy ³⁺、Tb ³⁺和Sm ³⁺等。其中, Pr ³⁺的研究较多, 发光波长涵盖面较广, 发射波段覆盖蓝光、绿光、红光、橙光; Dy ³⁺和Tb ³⁺因为能够发射黄光以填补Pr ³⁺的不足也吸引了广泛的研究; 此外, Sm ³⁺和Eu ³⁺也是典型的可见波段稀土发光离子。本文综述了近几年可见波段稀土离子掺杂激光晶体的研究现状, 主要以Pr ³⁺、Dy ³⁺、Tb ³⁺和Sm ³⁺掺杂YAlO₃ (YAP)、Mg : SrAl₁₂O₁₉ (SRA)等晶体为研究对象, 总结了一套适合Pr ³⁺掺杂材料的判据, 对晶体生长、结构、热学性能、偏振光谱性能和激光性能进行了系统的研究。     

Spectral dependence of the optical rectification effect in nanographite films

The spectral dependence of the optical rectification effect in nanostructured carbon (nanographite) films obtained by plasmachemical deposition was studied in a wavelength range from 266 to 1900 nm. In this range, the amplitude of the electric signal observed when films were irradiated by nanosecond light pulses of constant power increases in inverse proportion to the laser wavelength. The experimental results confirm the assumptions made previously concerning the mechanism of the observed effect. It is suggested that nanographite films are promising materials for detectors of ultrashort laser pulses in the IR, visible, and UV spectral intervals and for generators of electromagnetic radiation operating in the terahertz frequency range.