电场作用下染料掺杂液晶器件的激光辐射

通过在向列相液晶TEB30A中掺杂激光染料DCM和手性剂CB15制作了平面排列态液晶器件.采用Nd:YAG倍频532 nm波段激光作为泵浦光源,测量分析了平行于液晶器件表面方向的受激辐射光谱.当泵浦光较弱时,观察到了染料DCM较宽的荧光辐射谱;随着泵浦光的逐渐增强,辐射谱带逐渐变窄,辐射峰中心波长约为610 nm,最小...     

高精度双折射晶体定轴测厚仪

一、前言为研制透过带为0.12～0.15(?)窄带双折射滤光器,要求双折射晶片的光程差的偏差小于1/200波长,晶体光轴定向误差小于2′。而以往用常规仪器测定,厚度偏差只能达到1/50波长,定向误差约5′。为此,我们研制了高精度双折射晶体定轴测厚仪。本仪器用来测量晶体厚度、晶轴的方位角及晶体材料的双折射率(μ值)。测厚精度达1/(1000)波长,定轴精度优于1′,μ值可定准到5×10~(-5),测试数据稳定可靠。二、仪器的测量原理及精度1.晶体测厚原理及精度在两平行或正交的偏振片之间,放一片双折射晶体b(图1),其晶轴躺在通光面上,且与偏振轴成45°夹角。光束通过双折射晶体后,o 光和e 光之间有光程差σ为:     

Lu2SiO5晶体电子结构的模拟研究

基于密度泛函理论,GGA-PBE交换相关势研究了含氧空位和氧填隙的Lu2SiO5(LSO)晶体的电子结构。详细讨论电子态密度,分析了含氧空位的LGO晶体的电子态密度,结果显示,在禁带中出现了一个新的态密度分布,VO5能产生一个吸收带,该吸收带位于400~500nm之间。     

新显色剂NPNTT的合成及其与镉的显色反应

本文报道了1-(4-硝基苯基)-3-(4-硝基-噻唑)-三氮烯(NPNTT)的合成及其与镉的显色反应研究。在O(P聚乙二醇辛基苯基醚)的存在下,pH11.0的Na2B4O7-NaOH缓冲溶液中,该试剂能与镉发生显色反应,镉与NPNTT形成摩尔比为1:3型的配合物,在450nm处有一最大正吸收,在540nm处有一最大负吸收。以450nm为参比波长,540nm为测量波长进行双波长测定,表观摩尔吸光系数为5.23×105L/(mo·lcm),镉的浓度在0～400μg/L范围内符合比尔定律。用拟定方法测定废水中的微量镉,结果满意。     

纳米Fe3O4磁流体的制备及其影响因素研究

通过液相共沉淀法制备了Fe3O4水基磁流体,选择油酸作为表面活性剂,获得油酸包覆的Fe3O4纳米粉,将其分散于有机溶剂中,制备了纳米Fe3O4有机基磁流体。采用X-Ray衍射分析仪和粒径分布仪分析了生成物的结构和粒径分布;用FT-IR和高分辨透射电镜表征了生成物的成分和形貌。结果表明:制得的立方晶体纳米Fe3O4平均粒径为16.3 nm,FT-IR图谱中1 593、1 736和2 926 cm-1等处的吸收峰很强烈,这充分说明该纳米粒子被油酸很好地包覆;选择油酸作为表面活性剂,起到表面改性和萃取出纳米粒子的作用;制得的油酸包覆纳米Fe3O4粒子能够稳定分散于有机溶剂中。     

全固态复合内腔和频570nm连续波黄光激光器

研制了全固态连续波570nm黄光激光器,黄激光分别由两片Nd:YAG的1444nm和946nm谱线非线性和频产生,两条谱线分别对应各自的晶体能级跃迁4F3/2-4I15/2和4F3/2-4I9/2。实验采用复合腔结构,利用KTP晶体II类临界相位进行内腔和频。测量了570nm黄激光输出功率随泵浦功率的变化,结果表明,当注入到两片Nd:YAG晶体的泵浦功率分别为24W和15W时,获得了560mW的连续波570nm黄激光输出,其4h功率稳定度优于±2.8%。在输出功率为560mW时,采用光束质量分析仪测量了激光输出光斑质量,结果显示,在570nm最大和频激光输出时的光束质量因子M2为2.3。所提出的复合内腔和频技术可为新波长激光器的发展提供参考。     

6.5W LD泵浦914 nm钒酸钇激光器

掺钕钒酸钇作为一种重要的激光增益介质,以其受激发射截面大、对809 nm波长存在很强的宽吸收带、偏振发射等优点,在LD端面泵浦全固态激光器中得到了广泛的应用,其中比较有应用价值的受激发射谱线为1 064 nm,1 342 nm和914 nm。由于914 nm谱线属准三能级结构,以及钒酸钇晶体较低的热导率,限制了其向大功率方向的发展。研究了一种具有较高效率的大功率钒酸钇连续输出激光器,通过采用简单的折叠腔设计和对腔镜镀适当的介质膜,抑制了波长为1 064 nm和1 342 nm的高增益谱线。当泵浦功率为29W时,输出功率高达6.5W,斜效率为37.9%,光光转换效率为22.4%.     

基于1397nm波长H_2O分子吸收光谱的温度测量研究

为了准确获得燃烧场温度信息,利用可调谐半导体激光吸收光谱技术进行了气体温度测量实验。利用1397nm波长范围内的两条H_2O吸收谱线进行气体温度测量,简化了实验装置和数据处理的复杂程度。将两种测量方法得到的温度与管炉温度对比,可以看出直接吸收光谱的测量误差在3%以内,波长调制光谱误差在4%。结果表明,1397nm波长范围内的两条H_2O吸收谱线可以用于TDLAS气体温度的测量,并且测量的精度较高。     

基于二维荧光相关谱的多环芳烃重叠峰解析

以激发波长为外扰,基于二维荧光相关谱技术对蒽芘混合溶液中重叠的荧光峰进行有效解析。采集了蒽、芘单组份无水乙醇溶液的激发谱,选择了蒽和芘荧光强度单调变化的5个激发波长:270nm、320nm、325nm、330nm和340nm。在此基础上,采集浓度为5×10-5g/L蒽芘无水乙醇混合溶液在5个激波长下的荧光谱,并以选择的激发波长为外扰,构建同步和异步二维荧光相关谱。结果表明:在同步谱上出现5个较强的自相关峰,位置分别在369nm、379nm、391nm、400nm和424nm处;依据未被覆盖的蒽在424nm的处荧光与各波长处荧光交叉峰的正负,指出379nm和400nm处的荧光峰来自混合溶液中的蒽,而369nm和391nm处的荧光峰来自混合溶液中的芘。同时,又根据异步二维荧光相关谱交叉峰的有无,进一步确认和验证了混合溶液中各荧光峰的来源。     

谱线弯曲对成像光谱仪辐射信号采集的影响

为了研究谱线弯曲对棱镜色散成像光谱仪光谱辐射信号采集的影响。首先,给出探测器像元采集到的辐射能量的表达式。然后,结合复合棱镜的色散特性,在可见近红外光谱范围（400～1000nm）内,计算当光谱偏离量为0.01d、0.1d和0.5d（d为探测器像元尺寸）时系统采集到的辐射能量与没有谱线弯曲情况下系统采集到的辐射能量的归一化差值,衡量谱线弯曲下系统辐射测量的变化。结果表明：谱线弯曲引起的探测器上的光谱偏离导致系统辐射信号采集发生变化,与没有谱线弯曲的情况相比,采集到的景物辐射信号在大气吸收带的边缘出现明显的偏差,且信号的差值随光谱偏离量的增大而增大,当光谱分辨率提高时,一些较弱的吸收峰附近也会出现明显的信号偏差。对于光谱分辨率平均为10nm的成像光谱仪,谱线弯曲量应控制在0.3nm以内。     

用于植物培育实验的宽带负滤光片的研制

植物生长过程中对太阳光谱的吸收具有选择性。由于植物在光合作用和生长发育中对蓝紫光和红光较为敏感,因此设计并镀制了一种滤光片,目的是从太阳光谱中过滤掉植物吸收很少、且可能有害的黄绿光,从而采集植物生长所需要的蓝紫光和红光。通过离子源辅助电子枪蒸镀的物理沉积方式在大尺寸的K9玻璃基底上镀制了宽带负滤光片,镀膜后的滤光片在400~470nm和630~750nm波长范围内平均透过率大于90%,而500~580nm波长范围内平均透过率小于0.2%。结果表明该宽带负滤光片膜系的镀制满足植物培育实验的使用要求。     

An attenuated total reflectance far-UV spectrometer

An ultraviolet spectrometer based on attenuated total reflection (ATR) has been developed and tested for liquid water (light and heavy water) in the wavelength range from 140 to 300 nm, which includes the far ultraviolet (FUV) region. One of the principal limitations of FUV transmission spectra is the strong absorption of the solvent itself. High absorptivity of the n --> sigma(*) transition in water molecule has thus far prevented meaningful spectral measurements of aqueous solutions in the wavelength region under 170 nm. Our technique uses the evanescent wave created through total reflection when light is passed through an internal reflection element (IRE) in contact with the sample. Since the evanescent field is used as an optical path length, the method allows spectral measurements favorably comparable with that of transmittance method with a shorter path length than the wavelength of FUV light. In this study, we have designed an original miniature IRE probe made of sapphire that allows detection of the whole n --> sigma(*) transition absorption band of water down to 140 nm. The obtained ATR-FUV spectra closely match calculations based on the Fresnel formula. It is also confirmed that this spectrometer is equally effective for spectral measurements of nonaqueous solvents with significant absorptivities in the FUV region.     

面成型光固化方法研究

阐述了一种面成型的光固化成型加工方法,系统采用普通紫外光作为成型光源,它的频谱可以与光敏树脂的吸收频谱匹配,从而固化树脂材料.紫外光经过椭球反射镜的反射后,汇聚到聚光透镜的焦点位置,并且通过透镜产生平行的紫外光束.成型零件的截面特征是由位于光敏树脂上方的掩模产生的,通过对比实验F46薄膜、聚四氟乙烯薄膜、THV610薄膜、聚酯薄膜、石英玻璃、有机玻璃等掩模材料对于紫外光的透射率,证实几种塑料薄膜的紫外光透射率差别不大.在临界光学系统下进行的工艺实验结果表明,该成型方式能大幅提高零件的成型速度,是一种有效的成型方法.     

Variable rowland radius laboratory vacuum surface-sensitive x-ray absorption fine structure spectrometer

A new laboratory x-ray spectrometer for surface-sensitive extended x-ray absorption fine structure [(S)EXAFS] and surface-sensitive x-ray absorption near-edge structure [(S)XANES] measurements is described. The spectrometer employs a 12 kV mA rotating anode generator. It has a monochromator equipped with a set of exchangeable curved crystals of Johann or Johansson type with different cell parameters, orientations, and Rowland radii. The computer controlled movement system based on nine stepping motors allows all the main elements of the spectrometer to be positioned freely relative to the x-ray source and gives an opportunity to use sophisticated scanning modes (for example, a mode with a focus spot position on a sample surface instead of an exit slit). The whole x-ray beam line is completely enclosed in a vacuum chamber that is directly connected to the x-ray generator, thereby preventing the absorption of x rays in the air. This layout allows a wide x-ray photon energy range from a few keV up to dozens of keV. A registration of x rays transmitted through the sample with proportional counter- and photoelectrons emitted from the sample with channeltron is used to carry out bulk- and surface-sensitive measurements, respectively. Using a 25 x 200 kV mA power regime of a rotating anode x-ray generator, a photon flux of 2.5 x 10(5) counts/s was registered at the Cu K edge, where the energy resolution was about 5 eV. High near surface sensitivity is demonstrated by the EXAFS spectra of Cu K and Hf LIII edges measured from 3 nm Cu and Hf oxide films.     

半导体双波长透射式红外干涉仪的研制及应用

采用635nm波长半导体可见光激光和10.5μm波长半导体红外激光作为干涉光源,设计了635nm和10.5μm双波段共光路透射式红外干涉仪,实现了可见光波段干涉测试与红外光波段干涉测试共光路,且双光路共用可见光对准。双波段共用机械式相移系统,并采用635nm测试光分段驻点标定10.5μm测试时相移器的长行程误差。研制的双波长红外干涉仪系统的红外测试精度达到PV优于0.05λ,RMS优于0.02λ,系统重复性RMS优于0.001λ。采用该干涉仪测试口径为400mm×400mm,离轴量为800mm的离轴非球面,得到边缘最大偏差值为21.9μm,能够实现大口径离轴非球面从粗磨到精磨高精度加工面形的全过程干涉测试。     

A sample holder for soft x-ray absorption spectroscopy of liquids in transmission mode

A novel sample holder for soft x-ray absorption spectroscopy of liquids in transmission mode based on sample cells with x-ray transparent silicon nitride membranes is introduced. The sample holder allows for a reliable preparation of ultrathin liquid films with an adjustable thickness in the nm-μm range. This enables measurements of high quality x-ray absorption spectra of liquids in transmission mode, as will be shown for the example of liquid H(2)O, aqueous solutions of 3d-transition metal ions and alcohol-water mixtures. The fine structure of the x-ray absorption spectra is not affected by the sample thickness. No effects of the silicon nitride membranes were observed in the spectra. It is shown how an inhomogeneous thickness of the sample affects the spectra and how this can be avoided.     

Measurement of soft X-ray absorption spectra and elemental analysis in local regions of mammalian cells using an electronic zooming tube

Direct measurement of absorption spectra for minute areas (2 μm ×2 μm) in a dried mammalian cell was attempted using X-ray contact images of a whole cell. The wavelength region used ranged from 1.5 to 10 nm covering the absorption edges of the major cellular elements. The measurements were achieved taking advantage of synchrotron radiation as a tuneable light source and an electronic zooming tube as an X-ray detector with a high spatial resolution. The spectra in every intracellular area exhibited marked absorption changes at the absorption edges of carbon, nitrogen and oxygen, while minor but significant changes for iron and calcium were observed, particularly in the cytoplasmic areas. These results reveal the different spatial distributions of the constituent elements in a cell.     

Fully automated spatially resolved reflectance spectrometer for the determination of the absorption and scattering in turbid media

We describe a fully automated setup which is based on measurements of the spatially resolved reflectance for the determination of the reduced scattering and absorption coefficients in semi-infinite turbid media. The sample is illuminated with a xenon light source in combination with a monochromator enabling the scan of the wavelength from 450 nm to 950 nm. Reflected light from the sample is detected with a CCD camera providing a high spatial resolution. The essential steps for signal processing including, e.g., the consideration of the optical transfer function and the correct treatment of the background subtraction, are presented. The solutions of the diffusion theory and of the radiative transfer theory are investigated regarding the exact detection and illumination geometry. Systematic errors caused by using the different theories for fitting the optical parameters are characterized. The system was validated using liquid phantoms which contain Intralipid 20% and ink, and the measurement range of the system is specified. Further, we carefully characterized the optical properties of Intralipid 20% in the wavelength range between 450 nm and 950 nm.     

天空偏振光测量系统的设计

根据一束光的偏振特性可以由斯托克斯矢量来表征的原理,设计搭建了一种天空偏振光测量系统。该系统由计算机、赤道仪、光纤光谱仪和配备了可旋转偏振片的改进式天文望远镜组成,在400~900 nm的光谱分辨率为1.4 nm。赤道仪经过标定后可以实现0~180°方位角以及0~90°高度角的调整,角度分辨率为2.5°。系统的光学全视场为4.5°,使用该系统可以测量全天空的光强辐射度、偏振度以及偏振方位角。由标定结果可知,系统光强测量的重复率在450~500 nm为99%,在500~900 nm为(95±3)%;在400~750 nm偏振度测量误差＜2%,在475 nm处达到1.2%。偏振方位角的测量误差＜2°。