共光路径向剪切干涉仪的设计

针对常规像移式干涉仪无法用于大口径、长光路光学系统波像差检测的工程问题,设计了共光路径向剪切干涉仪以消除采用标准波面所引入的系统误差.设计中采用由三角棱镜与斜方棱镜组合而成的胶合棱镜组作为波面剪切器件,将待测波面与其复制波面产生干涉,并通过一组有不同相对孔径的透镜切换装置来控制干涉仪剪切比.与4D动态干涉仪在不同条件下...     

五棱镜的运动误差对波前测量的影响

五棱镜使光束转向时,它的工作状态的改变会给测量带来一定的误差,分析了五棱镜由于机械运动引起的在三维方向有微偏角时使光束转向改变波前的复杂情况,计算机模拟实验证明了由机械运动引起的波前改变量是可分离的,以便减小五棱镜的运动误差对测量的影响,使五棱镜光束转向系统在测量中发挥最佳效能。     

激光棒干涉测量中单双通法的对比

由于激光棒具有细长的特殊形貌特征,传统的双通测试方法虽然灵敏度较高,但是往往存在明显的衍射效应和多重成像导致的边缘黑环,这会导致有效测量面积的缩减,对于小口径光学元件的测量尤为不利。为了克服这一缺陷,采用单通法测量激光棒的波前畸变,使用直角棱镜作为反射件,使得测试光仅通过激光棒一次,从而减少光路中的等效圆孔数和成像次数,抑制衍射和边缘重叠。利用展开的多小孔模型讨论了衍射效应的影响,并且从成像角度讨论边缘重叠的成因,从而得出单通法的优势。另外,为使参考光与测试光的匹配,需要将直角棱镜旋转至少5.40°偏摆角以提高干涉条纹的对比度。最终测得激光棒波前畸变的峰谷值为0.068λ,均方根值为0.012λ。     

Ultimate characteristics of an X-ray prism spectrometer

X-ray prism spectrometry schemes for experimental investigations of fast processes are considered. Diamond and beryllium prism dispersion parameters and special features of transmission spectra for crystal prisms are analyzed. It is shown that relative energy resolution E/ΔE at photon energies E ∼ 10 keV may reach 10³–10⁴ and the total working spectral band is ∼100 keV. This opens unique possibilities for measuring fine structures of single-shot absorption spectra for quasi-parallel beams and continuous monitoring of the fundamental and high-frequency harmonics of an X-ray free electron laser. Original Russian Text ? A.G. Tur’yanskii, 2009, published in Pribory i Tekhnika Eksperimenta, 2009, No. 4, pp. 150–158.     

A New High-Resolution Tof Mass Spectrometer

ABSTRACT

UV laser-induced surface ionization with prism internal reflection is demonstrated to be a useful ion source for the Time-of-Flight mass spectrometer (TOF-MS). Spraying aniline (93 amu) on the prism surface and using 2 ns UV laser pulses, mass resolutions of 3,900 and 11,000 have been achieved in a linear TOF-MS and in a reflectron TOF-MS, respectively. Theoretical calculations indicate that mass resolution of over one million is possible, if a picosecond laser and appropriate electronics are employed.     

Compensating for the Influence of Nonstationary Thermal Distortions of Active Elements on the Position of the Output Beam of a Double-Pulse Laser for Holographic Interferometry

Optotechnical methods of stabilizing the spatial position of the output beam of a double-pulse laser under conditions of wedge- and/or lens-shaped thermooptic distortions of solid-state active elements are proposed and investigated. In the master laser, thermal distortions were compensated for using a stable cavity, in which the active medium was located in the region of the center of curvature of a totally reflecting mirror. In the amplifier, a two-pass scheme was applied. It included a return reflector composed of a positive lens, an erecting prism, and a right-angle roof prism. These methods allowed the interval between paired pulses in holographic lasers, which are constructed on the basis of conventional two-lamp pumping systems, to be extended. The pulse separation in the millisecond range (10^–3–1 s) is controlled by the time shift in the flash of one of the lamps at the pulse generation within each flash.     

Formation of variable-spatial frequency interference patterns with the use of birefringent crystal prisms for laser Fourier spectroscopy

Splitting of orthogonally polarized radiation components at the exit of birefringent crystal prisms (BCPs) having a special structure and fabricated from uniaxial Iceland spar crystals is studied by the vector analysis method. For these prisms, the angle of splitting between the ordinary (o) and extraordinary (e) beams at the BCP exit depends linearly on the angle of incidence of a collimated laser beam onto the BCP entrance face. This dependence has the maximum slope only for two fixed orientations of the optical axis vectors a ₁ and a ₂ in both crystal wedges (BCP components). As a result of interference of polarized o- and e-waves, a straight-line interference pattern with a controlled and smoothly changed spatial frequency in the range from 0 to 125 periods/mm can be formed directly at the BCP exit. The BCP ability to form a sinusoidal interference pattern with the modulation depth not lower than 30% and with a varied spatial frequency at the aperture up to 30 mm makes it possible to use the BCP as a basis for creating a compact static Fourier spectrometer with the ultimate theoretical resolution λ/Δλ up to ∼2000.     

一种激光束形参数简便测试方法

在以激光作为测试光源的高精度测试装置中,激光器实际输出的束形参数值与其标称值的偏离会直接传递并影响到后续测试结果的准确度。提出一种基于CCD的多点测试方法,此方法在不降低测量精度的条件下可实现激光束形参数的简便测试。在搭建的测试装置上实现了633nm He-Ne激光器束腰半径、远场发散角和M2质量因子的测量,可以方便地评价激光光束质量。将束形参数简便测试方法的结果与法国Phasics公司的SID4波前探测器的测量结果进行了比对,结果表明,激光束形参数简便测试方法不仅能用于激光束形参数的简便检测,而且具有较高的精度。     

金属薄膜边缘诱导改变谐振激光模式实验

为研究在不同方向移动的金属薄膜边缘的干扰情况下谐振激光模式的改变现象,调节定制的氦氖激光谐振腔产生高阶高斯光束,用金属薄膜边缘进行干扰,并用CCD相机对光束的演变过程进行详细记录。随着金属薄膜边缘沿X和Y正方向上位移的增加,出射的激光模式由高阶向低阶模式演化,然后变成基模,变弱直到消失。原始激光模式的阶数越高,它的演化模式光斑形状越丰富。当用金属薄膜上方边缘向Y轴正向缓慢移动进行干扰时,激光模式的演化规则是最后趋于沿X轴的分裂模式;当用金属薄膜的左侧边缘向X轴正向缓慢移动进行干扰时,激光模式的演化规则最后趋于沿Y轴的分裂模式。     

Experimental characterization of the flow field of square prism with a detached splitter plate at high reynolds number

The characteristics of the flow field of a square prism with detached splitter plate in its wake were investigated by measuring the fluid force on the prism and by visualizing the flow field through particle image velocimetry (PIV) with a high Reynolds number (Re = 10,000). The experimental parameters included the ratios of the splitter and prism widths (H/B = 0.5–1.5) as well as the gap ratios (G/B = 0–2) between the prism and the splitter plate at a high Reynolds number (Re = 10,000). The drag reduction rate of the square prism increased with increasing H/B for the same G/B; meanwhile, it increased and then decreased with increasing G/B for the same H/B. When the detached splitter place was installed, vortices rotating in opposite directions were generated on its upper and lower sides. Reverse flow was caused by the vortices in the wake region of the square prism, and the prism drag was decreased by the reverse flow.     

剪切干涉仪的定量处理数学原理及采样处理技巧

介绍了剪切干涉仪适时定量处理的方法。通过互相垂直两个方向的剪切图形 ,解算出镜面的实际形状。提出两种处理方法 :即变换系数法和扩展了的联立方程求解法。然后介绍了在采样和处理过程中的技巧 ,最后对剪切干涉棱镜的发展和如何将移相干涉技术应用到剪切干涉中的可能性 ,做了初步的探讨。     

一种滚转角和直线度同步干涉测量方法的研究

提出一种用于精密线性位移台滚转角和运动直线度同步测量的激光外差干涉系统。该干涉系统由一个Koster棱镜、角隅棱镜、分光镜、1/2波片、直角棱镜、1/4波片以及楔面棱镜和楔面反射镜组成。楔面棱镜作为测量运动直线度和滚转角的传感器固定在线性导轨上,当双频激光器的光射入干涉系统中后,形成空间对称的六光束测量信号。空间结构对称、系统共光路的特点使光学分辨率比普通的迈克尔逊干涉仪高一倍,光程死区达到最小。系统稳定性好,抗环境干扰能力强。光路对称使得增加或减小的光程变化相同,其他自由度引起的光程变化相互抵消,仅有运动直线度和滚转角的变化可以进入光程差,有效地排除其他自由度及阿贝误差的串扰,实现高精密测量。试验证明相互平行且不同频率的两束光在同一反射系统中发生运动直线度偏移和滚转角变化时,通过两束光携带的不同相位信息能直接得到运动直线度和滚转角的变化值。它不需要一条与行程同样长度的大反射镜作参考便能够实现高分辨率测量,简单实用,可直接溯源米定义。     

偏振相移技术在DIC显微术中的应用研究

微分干涉（DIC）显微技术使用诺曼斯基棱镜完成光束的分割、合成、最后发生干涉,将样品上各个部分折射率、厚度的变化率或表面起伏的不同转化为像面上光强的差别,一般情况下,无法进行定量测量。文章将激光偏振相移技术应用于DIC显微术中,建立并推导出光学数学模型。该模型利用无限远光学系统优化系统光路,使系统减小了因为使用激光光源、     

A setup for measuring the temperature dependence of the refractive indices of solids

A setup for measuring the temperature dependences of refractive indices n(T) of semiconductors and dielectrics in the temperature range 300–700 K at the wavelengths of a He—Ne laser λ=0.63, 1.15, and 3.39 μm is described. Samples in the form of plane—parallel plates serve as Fabry—Perot etalons the optical thickness of which depends on the temperature. Upon heating and subsequent cooling of a sample, interference oscillations of the refiected-light intensity are recorded and used to determine the dependence n(T). The values of the refractive index at room temperature and the thermal expansion coefficient used in calculations are taken from the literature. Comparing the interferograms obtained for a heated and cooled sample allows evaluation of the temperature difference between the sample’s probed area and a measuring thermocouple. The relative error in determining thermooptical coefficient dn/dT in the range 300–700 K is within 1%.     

基于单压电变形镜的可控环形焦斑整形

为了实现可控环形焦斑的整形,提出了一套基于单压电变形镜的整形方法。首先结合波前衍射理论和随机并行梯度下降算法模拟迭代出环形焦斑整形所需的调制相位,进而利用波前传感器探测光束的波前信息,控制变形镜重构目标光斑对应的调制相位,实现聚焦光斑的整形。搭建了一套基于62单元单压电变形镜的光斑整形实验平台,采用焦平面上的CCD记录远场聚焦光斑。实验结果表明,该方法实现了对不同直径(0.32,0.4,0.6 mm)和宽度(0.05,0.08,0.1mm)环形焦斑的整形,可有效应用于激光束整形。     

Design of interference fits via finite element method

Studies of interference fits in ring gear-wheel connections show that the traditional design method based on thick-wall cylinder theory has some limitations. Application of the finite element method (FEM) for the three-dimensional stress analysis of interference fitted connections gives more complete and accurate results than the traditional method. An improved design method utilizes two safety factors, λ_s and λ_p, providing a new approach for evaluating the quality of interference fits. A tolerancing method utilizing the I_max and I_min curves provides a quantitative guideline for interference fit design. The selective assembly method combined with the FEM-based method for interference fit design provides an effective approach to achieve more reliable interference-fitted connections and more precise assembly with lower manufacturing cost.     

A prism combination for near isotropic fluorescence excitation by total internal reflection

Total internal reflection fluorescence (TIRF) microscopy is finding increasing application for selectively detecting molecules at or near a glass–water surface. As with all fluorescence methods, the efficiency of excitation of a fluorophore is potentially sensitive to the polarization state of the source. In TIRF, s‐polarized excitation produces an evanescent field that is perpendicular to the incident plane (y direction), whereas p‐polarized light generates a more complex pattern but one dominated by a field that is vertical to the surface (z direction). Thus, fluorophores whose absorption dipoles are fixed in the x direction are not favourably aligned for excitation. Here we describe a beam‐splitting prism arrangement that allows excitation by two orthogonal beams, thus giving isotropic excitation in the x–y plane with s‐polarized light. With linearly polarized light at the magic angle, near isotropic excitation in three dimensions should be achieved. This prism design should find application in polarized fluorescence microscopy to investigate the rotational motions of macromolecules or to minimize flickering of fluorescence emission arising from molecular rotations in single molecule studies.     

In Situ analysis of CO2 laser irradiation on controlling progression of erosive lesions on dental enamel

The present study aimed to evaluate in situ the effect of CO₂ laser irradiation to control the progression of enamel erosive lesions. Fifty‐six slabs of bovine incisors enamel (5 × 3 × 2.5 mm³) were divided in four distinct areas: (1) sound (reference area), (2) initial erosion, (3) treatment (irradiated or nonirradiated with CO₂ laser), (4) final erosion (after in situ phase). The initial erosive challenge was performed with 1% citric acid (pH = 2.3), for 5 min, 2×/day, for 2 days. The slabs were divided in two groups according to surface treatment: irradiated with CO₂ laser (λ = 10.6 µm; 0.5 W) and nonirradiate. After a 2‐day lead‐in period, 14 volunteers wore an intraoral palatal appliance containing two slabs (irradiated and nonirradiated), in two intraoral phases of 5 days each. Following a cross‐over design during the first intraoral phase, half of the volunteers immersed the appliance in 100 mL of citric acid for 5 min, 3×/day, while other half of the volunteers used deionized water (control). The volunteers were crossed over in the second phase. Enamel wear was determined by an optical 3D profilometer. Three‐way ANOVA for repeated measures revealed that there was no significant interaction between erosive challenge and CO₂ laser irradiation (P = 0.419). Erosive challenge significantly increased enamel wear (P = 0.001), regardless whether or not CO₂ laser irradiation was performed. There was no difference in enamel wear between specimens CO₂‐laser irradiated and non‐irradiated (P = 0.513). Under intraoral conditions, CO₂ laser irradiation did not control the progression of erosive lesions in enamel caused by citric acid. Microsc. Res. Tech. 77:586–593, 2014. © 2014 Wiley Periodicals, Inc.     

同轴单棱镜整形研究

半导体激光器广泛地应用在国防、商业、工业等领域,对其光学准直是一项重要的工作。介绍一种新的半导体激光整形系统——同轴单棱镜整形系统,详细地叙述了单棱镜的设计原理。与其它整形系统比较,该棱镜具有设计、加工和装调简单等优点,最大的优点还能保证光束同轴。最后以一个θ⊥×θ∥=25°×11°半导体激光器为例子,设计一个2.5×单棱镜同轴整形系统,通过软件模拟计算与实际计算结果比较,结果基本相符,证明了设计方法的正确性。     

高功率激光热效应对合束系统的影响

提出利用镀膜合束的方法对三路光束进行合束用于高功率红外激光合束系统设计。考虑系统中关键元件使用的红外材料ZnSe易受热效应影响,采用光机热耦合分析方法,研究了在温度边界条件固定时,各波段激光所产生的耦合热效应对各路激光波前畸变的影响,同时定性分析了系统中存在的激光偏置热效应。研究结果显示,系统中各波段的激光波前畸变均方根值(RMS)均满足设计要求(各波段波前畸变小于λ/8);激光偏置造成的波面高频成分增大了长波激光波前畸变量,但高频成分对系统波前畸变影响依然满足要求;轴向温差可在35s达到平衡,对光束波前造成主要影响的是各块镜片的面型畸变。根据分析结果搭建了实验平台,利用系统中短波400 W激光进行实验,采集了该条件下的面型并与仿真结果进行了对比,实验结果验证了该分析方法计算结果的准确性。