中国近海悬浮颗粒物海水声波衰减

在对颗粒物声吸收机理分析的基础上,根据已有的南黄海和莱州湾海洋调查数据,对中国近海实际海域悬浮颗粒物海水在声呐工作频段内的声波衰减进行了计算分析.结果表明,在悬浮颗粒物浓度高的海水区域内,悬浮颗粒物粘滞性声吸收所造成的声波衰减与不计及颗粒物存在的海水声吸收相比不可忽略.计算分析同时表明,在声呐工作频段内,颗粒物的散射声吸收可以忽略不计.取可使粘滞衰减为较大值的粒径为5 um的悬浮颗粒物海水进行计算,在低于几十千赫兹的频率范围内,当泥沙类悬浮颗粒物浓度高于O.1 kg/m3、有机类悬浮颗粒物浓度高于1 kg/m3,颗粒物粘滞衰减系数将大于清澈海水的衰减系数.泥沙类悬浮颗粒物海水浓度高于0.1 kg/m3、有机类悬浮颗粒物海水浓度高于1 kg m3,可以作为是否需要计及颗粒物声吸收的比较保守的估计判据,或是作为悬浮颗粒物海水达到声学混浊的估计判据.     

外并干涉仪中声光调制器特性对测量精度的影响

提出并论证了混合型声光调制器衍射光的笛射级次混叠特性,它使衍射光强中存在着驱动射频率的谐波项,此外入射光束的漂移将引起衍射光的频率漂移。分析了在外差干涉仪中应用它们对精度的影响,提出了消除这些因素影响的方法;利用双声光调制器外差干涉,并在干涉仪的内部提取测量的参考信号。用双声光调制器的外差干涉仪可以纳米测量。     

法-珀干涉绝对距离测量中的声光移频器双通道配置方法

为在能量天平动圈位移测量中实现大范围纳米精度法-珀干涉绝对距离测量, 提出了声光移频器双通道配置, 实现了调谐范围为200 MHz的可调谐频差. 通过分析声光移频器调制带宽与衍射效率的平衡与入射光束聚焦透镜的关系, 确定透镜的最佳焦距范围; 利用零级光斑分布特点准确定位入射光束, 保证一级衍射光束质量. 声光移频器在调制带宽内的实验单通道和双通道峰值衍射效率分别为79.54%, 61.41%; 声光移频器双通道配置输出的一级衍射光束与入射本征光束的拍频范围为440-640 MHz, 是单通道调制带宽输出220-320 MHz的两倍, 信噪比好. 理论分析表明, 声光移频器双通道配置方法实现的可调谐频差可测量腔长变化范围约为53 mm的折叠法-珀腔.     

模拟核素固化体Gd2Zr2-xCexO7(0≤ x≤ 2.0)的物相及化学稳定性研究

为研究钆锆烧绿石固化Pu(Ⅳ)的相变化情况及化学稳定性, 以Gd₂O₃, ZrO₂为原料, Ce(Ⅳ)作为Pu(Ⅳ)的模拟替代物质, 采用冷压热烧结的方法制备出Gd₂Zr_2-xCe_xO₇(0≤ x≤ 2.0)系列样品. 分别在40 °C和70 °C的合成海水中, 对固化体的长期浸出性能进行研究. 借助粉末X射线衍射仪对所制备样品的物相信息进行收集, 利用等离子体质谱仪对固化体的浸出浓度数据进行分析. 研究结果表明: 当x ≤0.08时, 固化体保持为烧绿石相; 当x>0.08时, 固化体转变为具有缺陷的萤石型结构相. 固化体中Gd³⁺, Zr⁴⁺和Ce⁴⁺在合成海水中, 随着浸泡时间的延长浸出浓度逐渐上升, 70 °C下的浸出浓度高于40 °C下的浸出浓度. 在42 d时, 固化体中Gd³⁺的最大浸出浓度在0.032 μg·ml^-1以下, Zr⁴⁺的最大浸出浓度在0.003 μg·ml^-1以下; Ce⁴⁺的最大浸出浓度在0.032 μg·ml^-1以下.     

反常氧化碲声光偏转器控制理论研究

根据晶体的声光特性以及反常布喇格衍射的Dixon方程,得出了氧化碲声光偏转器在反常布拉格衍射条件下的参量矢量关系.分析了超声波方向、入射光角度、衍射光角度与声波频率之间的关系.针对卫星光通信中衍射角固定的应用情况,通过数值求解和参量拟合,建立了一个基于平面方程的简单控制模型.利用该模型可以很快得到超声控制频率,使衍射角固定不变.     

反常氧化碲声光偏转器控制理论研究

根据晶体的声光特性以及反常布喇格衍射的Dixon方程,得出了氧化碲声光偏转器在反常布拉格衍射条件下的参量矢量关系.分析了超声波方向、入射光角度、衍射光角度与声波频率之间的关系.针对卫星光通信中衍射角固定的应用情况,通过数值求解和参量拟合,建立了一个基于平面方程的简单控制模型.利用该模型可以很快得到超声控制频率,使衍射角固定不变.     

外差干涉仪中声光调制器特性对测量精度的影响

提出并论证了混合型声光调制器衍射光的衍射级次混叠特性, 它使衍射光强中存在着驱动频率的谐波项, 此外入射光束的漂移将引起衍射光的频率漂移。分析了在外差干涉仪中应用它们对测量精度的影响, 提出了消除这些因素影响的方法： 利用双声光调制器外差干涉, 并在干涉仪的内部提取测量的参考信号。用双声光调制器的外差干涉仪可以实现纳米测量。     

Raman-Nath衍射与Bragg衍射的判据

一、前 言 声光衍射现象依据其工作条件的不同可分为 Raman-Nath衍射与Bragg衍射.Raman-Nath衍射是入射光通过声光互作用介质后形成多级衍射光的衍射;Bragg衍射是以Bragg角θa入射的光束,通过声光互作用介质后衍射光只有零级和一级的衍射.满足什么条件才产生上述两种不同的衍射?所应满足的这种条件即称为Raman-Nath衍射和 Bragg衍射的判据.很显然,这一判据对于设计各种声光器件都是很重要的.以前人们曾普遍采用Klein和Cook[2]提出的Q判据.这一判据指出,Q《1为Raman-Nath衍射; Q》1为 Bragg衍射.其中Q=2。IL/A‘,几为介质中的光波长…     

声光衍射下He-Ne激光光强分布实验探讨

论文介绍了声光衍射的分类,概述了He-Ne激光在拉曼-奈斯声光衍射下光强分布的实验过程,探讨了声光衍射下He-Ne激光光强分布的特点及实验意义等.     

声光调制器偏振特性的实验研究

声光调制器利用声光晶体的声光效应对输入信号进行外调制。另外,实验结果也表明:由声光调制器出射的衍射光存在偏振态的改变。旋转起偏器的透振方向,拉曼—纳斯衍射的一级衍射光的偏振态发生变化;且各级衍射光的偏振度随着透振方向的改变而发生周期性的变化。     

Effect of the spatial structure of an acoustic field on Bragg’s acoustooptic diffraction under strong acoustic anisotropy conditions

Bragg’s acoustooptic diffraction in an acoustically anisotropic medium is considered taking into account the two-dimensional spatial diffraction structure of the acoustic beam. The conditions are determined under which reverse transfer of optical power from the diffracted to the transmitted beam in the regime of 100% efficiency of diffraction is considerably suppressed. It is shown that this effect is due to diffraction bending of wave fronts of the acoustic beam in the acoustooptic diffraction plane. The problem of optimization of the piezoelectric transducer size and the spatial position of the input light beam is solved using the criterion of the minimal required power of the acoustic field. The results of simulation in a wide range of the acoustooptic interaction parameters for a Gaussian light beam are reported. The correctness of the model is confirmed experimentally. Recommendations for designers of acoustooptic devices are formulated.     

Two-coordinate diffusion of optical beams by an acoustooptic Raman-Nath modulator based on a paratellurite crystal

Acoustooptic Raman-Nath diffraction by a standing acoustic wave in a paratellurite crystal is investigated. An acoustic line is made in the form of a polished cube and serves as a high-Q acoustic resonator. A slow shear wave is excited by a single piezoelectric transducer. Multiple lossless sound reflections lead to two-coordinate light diffusion. When the acoustic intensity introduced into the crystal is about 2 W/cm² at a sound frequency of 7 MHz, there appears a diffraction pattern in the form of a homogeneous light spot with a solid angle of about 0.5 sr. An explanation for the features of the acoustooptic interaction is given. It is shown that this type of diffraction is helpful in designing acoustooptic two-coordinate diffusers of light beams.     

Acoustooptic nonpolar light controlling devices and polarization modulators based on paratellurite crystals

A complex of investigations and projects aimed at solving problems of highly effective acoustooptic control of nonpolarized laser radiation is generalized on the basis of anisotropic Bragg’s diffraction in a TeO₂ crystal from a slow acoustic wave, which is characterized by extraordinarily high acoustooptic quality. Modulators of the zeroth diffraction order, modulators of the first Bragg’s order, and a polarization-insensitive deflector are considered. The developed systems ensure the control of the polarization state of optical radiation. These systems are employed in setups and devices based on high-power solid-state and fiber lasers with a wavelength of 1.06 μm.     

Acoustooptic multiplication of the frequency shift of optical radiation on the basis of bragg polarization splitting

A technique for the acoustooptic multiplication of the frequency shift of an optical beam is proposed. The technique is based on the cascade diffraction of the beam by a single acoustic wave with the use of Bragg polarization splitting in a uniaxial crystal. The fundamental possibility of the practical realization of the technique is confirmed experimentally by using anisotropic acoustooptic diffraction in LiNbO₃.     

Investigation into the acoustooptic properties of tellurium crystals by anisotropic diffraction of light

The optical, acoustic, and acoustooptic properties of tellurium crystals viewed as a candidate material for mid-and far-IR acoustooptic devices are considered. The phase velocities, polarization, and drift angles of the acoustic energy in different crystal planes are calculated. The acoustooptic figure of merit for tellurium under the anisotropic diffraction conditions is estimated, and light-sound interaction geometries promising for acoustooptic applications are discussed. Measuring data for the optical and acoustooptic parameters of tellurium crystals are given.     

Acoustooptic interaction in two-dimensional photonic crystals: Efficiency of Bragg diffraction

We obtain equations for the Bragg regime of acoustooptic diffraction of light in two-dimensional photonic crystals. We determine applicability conditions of the single-wave approximation, in which it is sufficient to take into account only one Fourier component of each of Bloch waves involved in the acoustooptic interaction. In the single-wave approximation, we obtain formulas that make it possible to estimate the acoustooptic figures of merit of a photonic crystal. We show that, in a photonic crystal, higher acoustooptic figures of merit can be achieved than in the materials that make up the crystal.     

离子束蚀刻微透镜中蚀刻深度允许误差的研究

基于衍射光学原理,获得了微透镜的衍射效率与蚀刻深度误差之间的关系式。研究表明,离子束蚀刻中目前采用的时间控制法可满足Ｌ＝１时的微透镜微加工要求,但未能满足Ｌ＞１时的微透镜微加工要求。对Ｌ＞１的情形,需要提高蚀刻深度控制精度以使蚀刻深度的误差小于８７ｎｍ。     

Investigation of anomalous acoustooptic interaction in lithium niobate crystal

Expressions are derived for the calculation of the central frequencies f _1,2 ⁰ , and the frequency band f of wide-band anomalous acoustooptic interaction in crystals of arbitrary symmetry class. The effect of the difference between the ray and phase velocities of the diffracted light on the magnitude of f _1,2 ⁰ and f is pointed out. Results are presented of the computed acoustooptic quality factor M₂, the frequencies f _1,2 ⁰ , f and the electromechanical coupling constant for the tangential field k_D for cuts of LiNbO₃ crystals ensuring maximum diffraction efficiency. It is shown that the maximum M₂=22.10^–18 cgs units in this crystal is attained in the case of anomalous light diffraction by the slow shear wave propagating in the Y-120 direction. To the same cut there corresponds the maximum K_D=0.685. The design of anomalous acoustooptic deflectors developed is described. Experimental results are presented.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 7, pp. 42–47, July, 1981.     

声光效应原理及应用

讨论了声光效应,介绍该效应在激光印刷机及军事上的应用。     

声光技术在雷达上的主要应用

通过对声光器件原理、结构和特性的简要回顾 ,着重介绍声光技术在雷达领域中的相关应用 ,其中包括频谱分析、相关处理、延时控制、相控阵等四个方面 ,给出了相应的应用示意图 ,作了一定的说明和分析 ,简单介绍了未来声光技术的发展