He-Ne激光对钝顶螺旋藻的诱变效应

利用He-Ne激光(波长632 nm，功率10 mW)诱变钝顶螺旋藻IS（Spirulina platensis IS），经过一定时间的辐照，选取生长较快的藻种测量其β-胡萝卜素、蛋白质及多糖含量，进一步筛选出生长快、高产胡萝卜素或高产蛋白质的藻种.实验结果表明：与出发藻种IS相比，经He-Ne激光15min和25 min照射后的藻种MS-1、MS-2和 MS-3，藻丝形态发生变化，藻丝变短、螺旋变紧密，生长速度明显加快，其中 MS-1的β-胡萝卜素含量增幅为18.1%，MS-3的蛋白质和多糖含量均有较大增加.此外通过对出发藻种和诱变藻种的叶绿素a和胡萝卜素的紫外吸收光谱进行比较，发现诱变藻种与出发藻种相比最大吸收峰值略有变化，从而说明He-Ne激光对于钝顶螺旋藻的诱变效应.     

激光偏振性对亚心形扁藻生物效应的影响

实验研究了偏振与非偏振激光对亚心形扁藻的促长作用、叶绿素含量以及色素粗提物吸收光谱等生物学效应的影响.采用488 nm,70 mW输出功率的氩激光,辐照哑心形扁藻,隔天取样进行细胞计数,培养至第6天提取叶绿素,测量叶绿素含量并扫描叶绿素的吸收光谱.实验结果表明,偏振激光与非偏振激光辐照对藻细胞密度、生长速率的促长作用区别不显著;偏振性与否对叶绿素含量的累积没有明显的区别;激光偏振性对色素粗提物的吸收光谱没有影响.激光偏振性与否均可对亚心形扁藻的生物效应产生有效的作用,激光偏振性与激光生物效应关系的研究有待于进一步深入.     

激光辐照对湛江等鞭金藻的复壮作用及机制研究

用Nd∶YAG激光（波长1.06 μm,功率密度6 W/cm2）对长期保存的湛江等鞭金藻藻种进行辐照处理.研究了激光辐照对藻生长和生理生化特性的影响,并从藻细胞的超微结构和自体荧光特性的变化探讨了激光复壮藻种的可能机制.实验结果表明：辐照剂量为30 s~60 s时,有较好的复壮效果,藻种的生长速率、细胞干重、叶绿素、类胡萝卜素及蛋白质等含量均较对照组有不同程度的提高,增幅约25.3％～48.3％.激光复壮后的藻细胞,线粒体数量增多,光合片层进一步发育.辐照剂量增至90 s时,胞内脂质颗粒增加.藻种的自体荧光光谱中,波长682 nm处的荧光强度明显增强.此结果说明,利用激光的“筛子”与诱变作用,可以提高饵料藻种的生物品质.     

Gd0.55Sr0.45MnO3薄膜光诱导电阻变化特性研究

分别采用固相反应和脉冲激光沉积的方法制备了电荷-轨道有序态锰氧化物Gd_0.55Sr_0.45MnO₃块材和多晶薄膜, 研究了薄膜在光诱导作用下的电阻变化特性. 实验结果表明该薄膜在整个测量温度范围内表现出了半导体型导电特性. 利用变程跳跃模型拟合电阻温度关系可知, 其电荷有序态转变温度为70 K. 激光作用致使薄膜电阻减小, 当激光功率度为40 mW/mm²时, 最大光致电阻相对变化值可达99.8%, 且在8 s的时间内达到了平衡态, 温度对其影响很小; 当激光功率度为6 mW/mm²时, 获得的最大光致电阻相对变化值为44%, 而且时间常数随温度的升高而增大, 这主要是由于光诱导和热扰动共同作用的结果.     

Si离子注入和H等离子体处理对单晶Si中空腔生长的影响研究

室温下首先采用160keVHe离子注入单晶Si样品到剂量5×10¹⁶ions/cm²,部分样品再接受80keVSi离子辐照到较高的剂量5×10¹⁵ions/cm²或接受高密度H等离子体处理.应用透射电镜观测分析了800℃高温退火引起的空腔的形成形貌.结果表明,附加Si离子辐照或H等离子体处理会影响Si中空腔的生长.就Si离子附加辐照而言,由于辐照引入富余的间隙子型缺陷,因此,它会抑制空腔的生长,而高密度H等离子体处理则有助于空腔的生长.定性地讨论了实验结果.     

提高拮抗菌WB3对番茄灰霉病菌拮抗能力的He-Ne激光与氯化锂复合诱变技术

利用He-Ne激光(波长632.8 nm,功率12 mW)与氯化锂复合诱变一株番茄灰霉病菌拮抗菌WB3,获得14株拮抗效果突出的菌株,其最大抑菌带宽为15.7 mm.综合单一诱变组里菌株致死率以及拮抗能力的大小,其中辐照时间为30 min,氯化锂浓度为1.2%时为复合诱变最佳条件.经过复合诱变,L8拮抗菌最高抑菌带宽可提高14%以上,而单一He-Ne激光诱变后抑菌带宽提高8.8%,单一氯化锂诱变后抑菌带宽提高9%.L8菌株生长迅速,经传代培养证明其抑菌性能具有稳定遗传性.该实验研究He-Ne激光与氯化锂复合诱变枯草芽孢杆菌WB3的方法可应用于番茄灰霉病的生物防治领域.     

提高拮抗菌WB3对番茄灰霉病菌拮抗能力的He-Ne激光与氯化锂复合诱变技术

利用He-Ne激光(波长632.8 nm,功率12 mW)与氯化锂复合诱变一株番茄灰霉病菌拮抗茵WB3,获得14株拮抗效果突出的菌株,其最大抑菌带宽为15.7 mm.综合单一诱变组里菌株致死率以及拮抗能力的大小,其中辐照时间为30 min,氯化锂浓度为1.2%时为复合诱变最佳条件.经过复合诱变,L8拮抗茵最高抑菌带宽可...     

新型MSM结构砷化镓半导体探测器的性能

研究一种新型双金属接触GaAs半导体探测器的性能,测量了²⁴¹Am 5.48MeVα粒子、⁵⁷Co 122keV的光子和⁹⁰Sr 2.27MeVβ粒子的最小电离粒子谱,比较了一个3×3mm²的GaAs芯片在经过¹³⁷Cs 662keV光子约1300rad辐照前后的电荷收集效率和能量分辨率.测量结果显示这种新型金属─半导体─金属(MSM)结构的半导体探测器不仅在室温下对各种粒子具有良好的探测能力,而且具有很好的抗辐照性能.     

光照强度对蛇足石杉共生蓝藻细胞悬浮培养的影响

以蛇足石杉孢子囊为材料,分离出蛇足石杉共生蓝藻细胞,研究光照强度对液体培养的共生蓝藻细胞生长的影响.研究结果表明,在光强500 Lx下,共生蓝藻的生长速率最大;增加光照强度(> 2000 Lx)将抑制共生蓝藻的生长,菌体褪绿变白;在共生蓝藻生长过程中,蓝藻细胞内叶绿素a的含量随着光强的增加而显著减少,这与其在强光照下生物量的降低呈正相关.不同光质实验结果表明,绿光和蓝光条件下蛇足石杉内生藻生长快而红光条件下藻体增殖最慢,这与在绿光和蓝光条件下藻体细胞合成的色素含量增高有密切的关系.实验结论:蛇足石杉共生蓝藻细胞适宜的光照条件是弱光光照,适宜的光质是绿光或蓝光.     

石墨改性环氧树脂抗强激光辐照性能

 在激光硬杀伤防护体系研究中,制备了鳞片石墨改性环氧树脂涂层,分析了它与辐照激光能量耦合作用规律,研究了其热烧蚀性能、隔热性能等抗激光辐照性能,并对不同参数激光辐照后该材料的损伤形貌进行宏观、微观分析,确定了损伤阈值与损伤形式。实验结果表明：石墨改性环氧树脂具有优良的抗强激光辐照性能,连续激光辐照下功率密度损伤阈值高于2 kW/cm²;高温下与激光能量耦合系数仅为10%左右,稳定热烧蚀率低至μg/J量级;具备优良的纵向隔热性能,高温下热导率在10 W·K^-1·m^-1以下;低功率密度激光辐照下损伤形式为轻微氧化,高功率密度激光辐照下则以汽化烧蚀为主;材料制备工艺简单,成本低廉,与被加固材料界面结合良好。     

激光二极管端泵微片固体激光器的研究

本文介绍了一种用波长为809nm的激光二极管(LD)端面泵浦厚度为1mm的微片Nd:YVO4全固化固体激光器。器件结构上采用了一种独特的光学系统,该系统由分别用于LD激光束的耦合和聚焦的两部分组成。由Nd:YVO4的一个平面与一个曲率半径为21mm的球面镜组成半共焦腔,以获得高的转换效率。文中详细讨论了单横模运转时的泵浦光与激光腔模之间的匹配问题。当泵浦光功率为400mW时,获得152mW的1064nm波长的TEM00模激光输出。器件阈值功率为48.3mW,总的光-光转换效率为38%,斜效率为43%.     

LD抽运Nd:LuVO4微片激光器性能研究

报道了一类新型的LD端面抽运Nd：LuVO₄微片激光器，讨论了在不同掺杂浓度，不同厚度和不同透过率下的激光性质，测定了在不同抽运功率下，微片最佳激光输出功率与LD抽运温度的关系.在2W抽运功率下获得923mW的1064nm激光输出，阈值为48mW，斜效率为52%.对微片制冷后斜效率提高到59%. 关键词： LD抽运 微片激光器 4')" href="#">Nd：LuVO₄     

Efficient laser operation and continuous-wave diode pumping of Cr2+:ZnSe single crystals

Efficient continuous-wave laser operation of Cr²⁺:ZnSe was demonstrated with an output power of 1400 mW at an absorbed pump power of 1900 mW from a Tm:YAG laser. Under continuous-wave diode pumping at 1.54 μm an output power of 15 mW was obtained from a Cr⁺²:ZnSe laser. Excited state absorption is shown to be negligible in the pump and laser spectral region. Received: 12 October 2000 / Published online: 30 November 2000     

Diode-pumped Nd:YCOB self-frequency-doubling blue laser at 468 nm

We report a continuous-wave (CW) self-frequency-doubling blue laser at 468 nm by a diodepumped Nd³⁺:YCa₄O(BO₃)₃ (Nd:YCOB) laser. With 14.3 W of diode pump power, a maximum output power of 211 mW in the blue spectral range at 468 nm has been achieved. The beam quality M² values were equal to 1.16 and 1.23 in X and Y directions, respectively. The output power stability over 30 min is better than 5%. To the best of our knowledge, this is the highest power laser at 468 nm generated by self-frequency doubling of a diode pumped Nd:YCOB laser.     

All-solid-state CW Nd:GdVO<Subscript>4</Subscript>-LBO red laser under direct 912 nm pumping

We report a red laser at 670.5 nm generation by intracavity frequency doubling of a continuous wave (CW) laser operation of a 1341 nm Nd:GdVO₄ laser under in-band diode pumping at 912 nm. An LBO crystal, cut for critical type I phase matching is used for second harmonic generation of the laser. At an incident pump power of 8.9 W, as high as 347 mW of CW output power at 670.5 nm is achieved. The fluctuation of the red output power was better than 3.7% in the given 30 min, and the beam quality factor M ² is 1.65.     

High power single-longitudinal-mode Nd:YAG CW laser using reflective volume Bragg grating as output coupler

The single-longitudinal-mode (SLM) laser system has been demonstrated using reflective volume Bragg grating (RVBG) as output coupler based on short oscillator. The laser is laser diode (LD) side pumped and the oscillator is composed of one surface of Nd:YAG and RVBG. The RVBG has good angle and wavelength selectivity in SLM laser system. The maximum SLM output power is 622.15 mW. The average opticsoptics efficiency is 17.2% and slope efficiency is 25.6%. The M ² factor is smaller than 1.3.     

Diode-end-pumped Tm,Ho:YVO<Subscript>4</Subscript> microchip laser at room temperature

Room temperature Tm, Ho:YVO₄ microchip laser operated around 2 μm was demonstrated for the first time to our knowledge. At a heat sink temperature of 283 K, a maximum output power of 47 mW was obtained by using a 0.25 mm length crystal at an absorbed pump power of 912 mW, corresponding to a slope efficiency of 9.1%. Increasing the temperature to 288 K, as much as 16.5 mW 2052.3 nm single-longitudinal-mode laser was achieved. The M ² factor was measured to be 1.4.     

Ultrasound assisted extraction of β-carotene from Spirulina platensis

This paper illustrates the Ultrasound Assisted Extraction (UAE) of β-carotene from Spirulina platensis. Various parameters such as extraction time, solvent type, biomass to solvent ratio, temperature, electrical acoustic intensity, length of the probe tip dipped into the solvent, duty cycle and pre treatment effect were explored for the extraction of β-carotene. From economic point of view, the optimal conditions for the extraction of β-carotene from Spirulina were 1.5 g Spirulina (2 min pre soaked in methanol) in 50 ml n-heptane at 30 °C temperature, 167 W/cm² electrical acoustic intensity and 61.5% duty cycle for 8 min with probe tip length of 0.5 cm dipped into the extracting solvent from the surface. The maximum extraction achieved under the above mentioned optimum parameters was 47.10%. The pre-treatment time showed a promising effect on the yield as pre-treating the biomass with methanol for 2 min before ultrasonication showed 12 times increase in extraction yield of β-carotene.     

LD泵浦的Nd:GdVO4/KTP腔内倍频激光器

基于对Nd:GdVO4晶体热焦距的测量及其1.06 μm激光基本性能,用三镜折叠腔研究了半导体激光器(LD)泵浦的Nd:GdVO4/KTP晶体的内腔倍频性质.当用从直径为200 μm的单光纤输出的低功率的半导体激光泵浦时,绿光的阈值是26 mW,光光转换效率为17.3%.当用从直径为1.55 mm的光纤束输出的高功率的半导体激光泵浦时,绿光的阈值是200 mW,光光转换效率为19.35%.