He-Ne激光器放电点火电压的实验研究

寻找能降低He—Ne激光器点火电压的外加催离剂．实验对He—Ne激光器的点火电压在阴、阳极被可见光照射、低放射源作用于放电管和阴极附近加强电场的条件下进行了测量．对不同外加条件作用下He—Ne激光器点火电压实验数据的误差进行了分析．实验结果指出，用可见光照射阴极或阳极不能降低He—Ne激光器的点火电压；能明显降低点火电压的因素可以是低放射源或外加强电场．     

多谱线He-Ne激光器中棱镜组件的热变形研究

拉曼散射分析通常使用多谱线He-Ne激光器作为光源。通过建立多谱线He-Ne激光器腔内棱镜组件的有限元模型,并进行热变形分析,得到了棱镜组件的热变形位移结果。讨论了在棱镜角度改变时多谱线He-Ne激光器输出谱线的变化情况,通过实验进一步验证了仿真结果的准确性。结果表明:多谱线He-Ne激光器长时间工作会使温度升高,严重影响其腔内棱镜的偏转角度,使得其输出谱线发生一定的漂移。当腔内温度继续升高到一定值时会导致激光器不出光,此时,应当采取散热装置或者温度控制措施。     

Exciton photoreflectance of semiconducting layer compound GaTe

Reflectance modulation produced by an intense secondary light beam (an 18 mW He-Ne laser) has been studied for wavelengths near the fundamental edge of the semiconducting layer-type compound GaTe as a function of temperature and intensity of the modulating light. To clarify the experimental lineshape, ΔR/R spectra have been transformed into the laser induced changes in the real and imaginary parts of the dielectric constant, through Kramers-Kronig relations. As the temperature is lowered, the energy spacing between adjacent peaks in the PR spectrum decreases, indicating that the electric field at the surface is also decreasing. The lineshape is independent of the intensity of the laser beam, in agreement with the picture that the secondary light beam is only slightly modifying the surface electric field.     

读出光光源对液晶光阀实验的影响

液晶光阀实验中一般是用带布氏窗的He-Ne激光器作为读出光光源,本文分析了普通He-Ne激光、半导体激光、卤素灯等常见光源在液晶光阀实验中应用的可能性和各自特点并进行了实验验证.     

一种新型多波长绝对距离干涉测量系统的研究

介绍了一种新型多波长绝对距离干涉测量系统。系统采用633nm的双纵模He-Ne激光器和629nm的He-Ne激光器,组成三级合成波长链对较大距离进行精密测量,并作了误差分析。系统采用高稳定度的声光晶体对各波长分别进行偏频,再用外差探测法测量出光束通过参考光路和测量光路后的位相差。简要介绍了629nm的He-Ne激光器的设计方案。     

低强度He-Ne激光照射巨噬细胞对其免疫活性的影响

利用新型化学发光试剂MCLA,通过光学方法,并改变激光功率和照射时间研究了低强度HeNe激光照射巨噬细胞对其免疫活性影响实验结果表明,巨噬细胞在适当的激光功率和照射剂量下可大大提高其免疫活性,而过大或过小的激光功率或照射剂量则不能激活其免疫活性的显著提高,甚至产生明显的抑制效应.     

Experimental research on spatial filtering of deformed laser beam by transmitting volume Bragg grating

Using transmitting volume Bragg gratings (TVBG) as a basis,an experiment on one-dimensional spatial filtering of a deformed laser beam is designed.The deformed laser beam results from a He-Ne laser beam modulated by an amplitude modulation plate with a spatial frequency of 7.2 mm·1.Results show that when the central wave vector of the deformed beam satisfies the Bragg law of TVBG,the spatial profile of the -1st forward-diffracted order is similar to that of the undeformed He-Ne laser beam due to the TVBG with a spatial frequency selective bandwidth of less than 5.0 mm·1.The higher frequency components of the deformed beam are filtered out in the optical near field.Thus,the TVBG cleanup of the spatiallydeformed laser beam is realized experimentally.     

氦氖激光器稳定性测试及功率谱分析

在使用氦氖激光的一些测试系统或控制系统中，氦氖激光的时间稳定性直接影响着测试的精度和控制的稳定性。为了提高系统测试精度或消除控制中的振荡，就必须了解氦氖激光器输出信号的强弱变化和它们的频谱。本文提出了一种氦氖激光器稳定性的测试方案。作者结合科研课题采用这一方案进行了多次内场和外场实验，利用微机进行数据采集，得到了多组激光输出强度随时间变化的数据，且编制了应用软件用极大熵法对采集的结果进行了频谱特性分析。文中给出了若干组测试结果曲线和相应的功率谱曲线。并对这些曲线进行了分析，得出了一些符合实验的结论，提出了若干改进的意见，已经得到了有关单位的采纳。     

增强UV-B辐射和He-Ne激光辐照对小麦离体叶绿体光化学活性的影响

利用低剂量的He-Ne激光和增强UV-B处理小麦叶绿体,研究了He-Ne激光对UV-B辐射损伤的修复效应.将提取的离体完整叶绿体分成CK(对照)、L(激光)、B(UV-B)和BL(UV-B和He-Ne激光复合处理)不同处理组.B、BL组经过不同剂量的紫外辐照处理(剂量依次为0.42 kJ·m－2·d－1,0.84 kJ·m－2·d－1 ,1.26 kJ·m－2·d－1),其中BL组被UV-B辐射处理后再用He-Ne激光(5 mW·mm－2)辐照.利用低温荧光法测定不同处理组小麦叶绿体荧光发射光谱的变化;用电导仪和Clark氧电极仪分别测量叶绿体膜透性和电子传递速率,膜透性的改变从一定程度上能反应膜的损伤程度;ATPase活性采用分光光度计测量.研究表明:He-Ne激光和增强UV-B辐射影响叶绿体激发能的分配,UV-B辐照达到1.26 kJ·m-2·d－1时,叶绿体几乎完全失去活性;He-Ne激光则从一定程度上能促进叶绿体的光化学活性.UV-B辐射后的叶绿体再经过He-Ne激光的辐照处理后,可以恢复部分光化学活性,但当叶绿体损伤严重,光化学活性完全丧失时,He-Ne激光对其没有激活作用.     

遗传算法在激光器谐振腔优化设计中的应用

讨论了用遗传算法优化设计普通激光器谐振腔参量的方法.以典型的50 cm长的氦氖(He-Ne)激光器为例,进行了具体计算.结果表明:对于输出相同的激光功率,模拟优化的谐振腔参量与传统局域化设计(非优化)的结果基本一致.通过适当匹配谐振腔参量,仍可提高激光(单模)的输出功率.     

He-Ne激光对增强UV-B辐射拟南芥抗氧化系统的损伤修复

以培养6周左右的拟南芥为材料,采用UV-B辐射（剂量1 KJ/m2/d）和He-Ne激光器（波长632.8 nm,输出功率5 mW·mm2,辐照时间60 s）对材料进行处理,分成CK（没有经过UV-B或激光辐照）组、B(UV-B辐射)组、BL（UV-B和激光复合处理）组和L（激光辐照）组4个不同处理组.结果表明:增强的UV-B辐射拟南芥幼苗导致MDA(Malondialdehyde)、超氧阴离子含量升高,GSH(Glutathione)含量降低,PAL(phenylalanine ammomia-lyase)、CAT(catalase)和APX(ascorbate peroxidase)活性升高,SOD(supemxide dismutas)活性降低.单独He-Ne激光处理使MDA、超氧阴离子含量降低,GSH的含量升高,SOD、APX、CAT的活性升高,PAL的活性降低.UV-B辐射后再用He-Ne激光进行后处理,发现与单独UV-B辐照处理相比,MDA、超氧阴离子含量降低,GSH含量升高,SOD、APX、CAT的活性升高了,PAL的活性降低了.因此激光在一定程度上提高了拟南芥叶片抗氧化能力,在此基础上讨论了其可能的形成机理.     

Mode effects in second harmonic generation and their uses for laser stabilization

The influence of laser modes on second harmonic generation has been investigated using a three mode He-Ne laser operating at 633 nm as the source of the fundamental radiation. Mode locking which occurs when the laser modes are symmetrically placed relative to the centre of the gain profile enhances the second harmonic signal. This effect has been used to stabilize the frequency of the He-Ne laser to ± 1.5 MHz.     

用刀口法测量氦氖激光基横模

介绍研究氦氖激光基横模的刀口法测量原理，给出实验装置和实验结果，这种方法能够证实氦氖激光基横模的光强分布是高斯分布，能够确定光斑的大小。     

Dynamics of laser-induced shock wave by optical probe in air

A new simple optical system based on optical beam deflection combining the holophote corner cube was developed in order to study the dynamics of laser-induced shock waves in air. In this method, we adopt a He-Ne laser beam as the detection beam. The He-Ne laser beam, reflected by corner cube, intersects the propagating shock wave at two successive positions. The measurement of the shock wave velocity benefits from the double peak signals induced by the same acting laser pulse, which is calculated from the time interval between the corresponding oscilloscope signals and the distance of the two He-Ne laser beams. By virtue of this setup, we are also able to determine the pressure of the generated shock waves. It is shown that this method is simple with a fairly good precision and is much easier than the conventional methods used for this task.     

Displacement sensor based on polarization mixture of orthogonal polarized He-Ne laser at 1.15μm

Displacement sensor based on the polarization mixture and the cavity tuning of the orthogonal polarized He-Ne laser 1.15μm is presented.The power tuning curves of He-Ne laser are irregular,and it is difficult to measure the change in cavity length.The distortion of the curves is caused by the higher relative excitation compared with the He-Ne laser at 633 nm.In view of its potential for the wider displacement measuring range,a new method of displacement sensing is developed.Experiments show that displacement measuring stability based on the method of the polarization mixture is better than that of the power tuning curves. The displacement sensor achieves the measuring range of 100 mm,resolution of 144 nm,and linearity of 7×10-6 .     

An intermittent frequency offset lock of a transverse Zeeman laser to an iodine stabilized He-Ne laser

A single-mode frequency stabilized laser with modulation-free and moderate power is desired as a light source for an ultra-high resolution interferometer system and/or a rapid laser calibration system. For this purpose, we developed a new stabilized laser system that utilizes intermittent control of a 2 mW transverse Zeeman stabilized He-Ne laser (Zeeman laser) with an iodine stabilized He-Ne laser (I2 stabilized laser). Because of the intermittent control, working time of the I2 stabilized laser is reduced. The Zeeman laser has two operational modes: independent and slave mode. In the independent mode, the Zeeman laser is stabilized through control of Zeeman beat frequency. Temperature dependent drift of the oscillation frequency during the independent mode is periodically corrected by the slave operation utilizing frequency offset locking to the I2 stabilized laser. Frequency instability of the Zeeman laser in independent and slave modes is 7.7X10-11 and 2.0X10-11, respectively, at the sampling time of 100 s.     

用超声光栅测量氦氖激光的波长

介绍了一种新的测量激光波长的方法,并与传统的迈克耳孙干涉仪测量的结果进行了比较.我们对汞光和氦氖激光在乙醇(97%)形成的超声光栅中的衍射光谱进行了测量研究,首先利用汞光数据计算得到了超声波在乙醇中的传播速度,并分析了温度对结果的影响,然后利用超声波波速计算了氦氖激光的波长,得到的结果与标准值相比的相对误差为0.55%.此方法操作简便,且有与迈克耳孙干涉仪可比的精度.     

光源的偏振态对动态光散射颗粒测量结果的影响

研究了在动态光散射纳米颗粒测量中,光源的偏振态对测量结果的影响。采用了粒径为100nm、体积浓度为0.5%的标准颗粒作为样品,使He-Ne激光通过起偏器得到0°～180°方向的偏振光,测量了散射光强、偏振度和粒径测量值的变化,计算了相应的粒径均值偏差和标准差,并将这一结果与无偏振He-Ne激光入射进行了比较。结果表明,当入射光为线偏振光时,偏振方向垂直于散射面时测量效果最好;另一方面,由于颗粒系散射迭加造成的散射光偏振度降低,使线偏振光源与无偏振光源产生的散射光偏振度无明显差别,证明在测量中可以使用无偏振He-Ne激光代替。     

Cancellation of laser dither modulation from optical frequency standards

We demonstrate the removal of the dither modulation from an iodine-stabilized He-Ne laser by using a frequency-modulated acousto-optic modulator and feed-forward techniques. This procedure reduces the linewidth of the beat between this laser and a flywheel He-Ne laser from 6 MHz to 8 kHz, the undithered beat linewidth being ~7 kHz. Dither suppression greatly reduces counter errors during beat measurements from stroboscopic effects between the counter's gate and the frequency of the dither modulation and increases the utility of the already formidable array of dithered laser frequency standards by making locking to them an easier task.     

氦氖激光对链霉菌原生质体种间融合频率的影响

采用双亲灭活原生质体融合技术对金霉素链霉菌(Streptomyces aureofaciens)和龟裂链霉菌(Streptomyces rimous)种间原生质体融合进行了研究,分别利用聚乙二醇(PEG)、He-Ne激光以及PEG与He Ne激光混合诱导融合,结果表明:PEG及激光的双重诱导作用,使链霉菌原生质体种间融合频率得到显着提高。通过同工酶谱分析对融合子进行了初步鉴定。