格兰泰勒棱镜高性能宽带减反射膜的优化设计及性能测试

格兰泰勒棱镜在光学领域有着重要的应用,透过比的高低和有效带宽的大小,直接影响着棱镜的品质.为了提高棱镜的透射率,拓宽有效使用带宽,借助于计算机辅助设计方法,设计了高性能多层减反射膜系:选用合适的光学薄膜材料,利用电子束蒸镀,借助于离子源辅助蒸镀,制作了高性能的宽带减反射膜.测试结果表明:平均剩余反射率小于0.5%,有效使用带宽在可见光区大于100 nm,达到了设计要求,提升了棱镜的品质.     

Total reflection in a uniaxial crystal–uniaxial crystal interface

Considering an interface between two uniaxial birefringent crystals, four reflected and four refracted waves for each incidence direction are obtained. Along this direction can propagate an ordinary wave and an extraordinary wave. Here, we present the analytic expressions for the four critical angles, from which each refracted wave no more exists as propagating wave. We show the variation in these critical angles for different interfaces varying the orientation of the incidence plane with respect to the optical axes. When both principal refractive indices of the second medium are smaller than those of the first medium, then the four critical angles exist for each incidence plane and for any direction of the optical axes. But, when one of the indices has an intermediate value between the values of the indices of the other crystal, we can chose the optical axes directions in such a way that certain critical angles do not exist. Therefore, we can select the refracted wave that is eliminated by total reflection.     

偏振干涉成像光谱仪中格兰-泰勒棱镜全视场角透过率的分析与计算

论述了自行设计研制的偏振干涉成像光谱仪的工作原理,分析了其核心部件格兰-泰勒棱镜的分光机理;运用光线追迹方法,推导出了格兰-泰勒棱镜全视场角透过率计算公式;通过计算机模拟分析了入射面、入射角和空气隙厚度对该棱镜透过率的影响,并利用方解石Sellmeier色散方程,给出了该棱镜在仪器系统要求的光谱范围内透过率与波长的关系曲线;实验测试结果与理论计算公式相符,验证了理论公式的正确性.     

晶体膜层效应对棱镜偏光镜透射比影响的理论研究

为满足现代光信息技术对偏光器件各项技术指标的苛刻要求,利用膜层理论推导出线偏振光垂直入射时棱镜偏光镜透射比的数学解析表达式,并对影响棱镜偏光镜技术指标的每个物理参量作了定量分析。通过计算机定量模拟表明：晶体厚度对透射比的影响幅度与中间空气膜层的透射比有着密切的关系,在晶体折射率等参量取某些特定值,中间空气隙的厚度h=26．2μm和27．4μm时,格兰-泰勒（Glan-Taylor）棱镜晶体厚度对总透射比的影响幅度分别为5．934％和7．034％,格兰-傅科（Glan-Foucauh）棱镜晶体的厚度对总透射比的影响分别为1．24％,8．893％;晶体厚度,空气膜层厚度,棱镜结构角共同影响棱镜偏光镜的透射比。这一理论研究克服以前棱镜偏光镜透射比公式不能定量分析晶体厚度对棱镜偏光镜透射比影响的缺点,对偏光器件的的设计,具有重要的应用价值。     

晶体的双参量调制及其应用

利用折射率椭球分析法,分析了某些具有多重光学效应的光学晶体在两个外场同时作用下的一些特有调制规律.结果表明,当晶体的折射率椭球方程的三个交叉项中只有一项x1x2不为零时,可以得到其外场诱导新主轴折射率及其主轴取向的简单计算式.据此可以揭示出某些晶体在两个外加电场同时作用下将具有双横向电光Pockels效应,例如ˉ6点群的电光晶体.但一般晶体在双横向应力作用下不具有与双横向电光效应类似的调制特性,其弹光双折射大小与其应力差成正比,其双折射主轴方向一般为固定值.在相互垂直的外加应力和电场同时作用下,某些晶体(例如ˉ43m点群晶体)的双折射大小与外加应力和外加电场的加权几何平均值成正比,且新折射率主轴旋转角由外加应力和外加电场的比值来确定.晶体的上述双参量调制特性对设计新型光学调制器或传感器具有重要指导意义.     

新型偏振干涉成像光谱仪中格兰-泰勒棱镜像质分析与评价

阐述了自行研制的新型偏振干涉成像光谱仪中重要偏光器件格兰-泰勒棱镜的分光机理,应用光线追迹法分析计算了光在格兰-泰勒棱镜中的传播规律与光线轨迹;推导出了任意角度入射时光线在棱镜中的传播方向及出射点坐标;给出了格兰-泰勒棱镜的像点位移和色差理论计算公式.该研究对晶体器件像质的分析计算及评价具有普遍的指导意义,为新型偏振干涉成像光谱技术的研究以及偏振干涉成像光谱仪的研制提供了重要的理论依据. 关键词： 偏振干涉成像光谱仪 格兰-泰勒棱镜 像点位移 色差     

Polarisation studies on the Raman spectra of cubic crystals

General expressions have been derived for the intensities of the three classes of Raman lines namely totally symmetricA, doubly degenerateE and triply degenerateF, in the case of cubic crystals under the following conditions. The direction of the incident beam which is polarised with its electric vector inclined at an angleα to the normal to the scattering plane makes an angleΘ with one of the cubic axes of the crystal. The transversely scattered light is analysed by a double image prism with its principal axes inclined at angleβ to the normal to the scattering plane, which is horizontal. For incident unpolarised light and Θ=22 1/2°, and the scattered light being analysed by a double image prism rotated through 45° from the position when its principal axes are vertical and horizontal? forA lines is equal to one, forE lines >1 and forF lines <1. This gives a method of classifying the Raman lines of a cubic crystal in a single setting. The results have been experimentally verified in sodium chlorate.     

Geometrical optics analysis for reduction of trapezoidal image distortion in a single prism-based optical fingerprint scanner

A single prism-based optical fingerprint scanner structure is mathematically analyzed by using geometrical optics approach. Important parameters including a tilting angle of the fingerprint accepting plane, a geometrical-optic distant difference, a trapezoidal image distortion, an object compression ratio, and an orientation of a two-dimensional image sensor are formulated for the first time in terms of all three angles of the prism and the prism material. In addition, based on our mathematical model, we propose to design all three angles of the prism in such a way that the plane accepting the fingertip observed from one side of the prism is normal to the optical axis of the system. In this way, the imaging plane is perpendicular to the optical axis, eliminating the trapezoidal image distortion and leading to ease of implementation. Experimental verification using three commercially available dispersion prisms made from three different glass materials and one prism based on our design concept shows that a prism with higher refractive index provides lower trapezoidal image distortion. The experimental data generally obeys our theoretical analysis.     

Polarization-maintaining fiber-based optical low-coherence reflectometer for characterization and ranging of birefringence

We describe a polarization-maintaining fiber-based polarization-sensitive optical low-coherence reflectometer for measurement of depth-resolved birefringence. Unlike for other fiber-based polarization-sensitive optical low-coherence reflectometers, here the linear birefringence of a sample can be measured from data recorded in a single A scan. Simultaneous measurement of retardation and orientation of birefringent axes with mica wave plates is demonstrated. The measured retardation is insensitive to sample rotation in the plane perpendicular to ranging.     

扩展琼斯矩阵在研究Solc滤波器离轴消光比中的应用

根据广泛使用的双折射材料的性质以及滤波器入射角有限的特点,讨论了晶体中o光和e光的关系;根据光的折射定律,将光在晶体表面的折射效果表述为输入、输出折射率矩阵;建立了从入射面坐标系到晶体本征坐标系的坐标变换矩阵;推出了简化的扩展琼斯矩阵。整个过程物理思想清楚,每个矩阵表示的物理意义直观、明确,得到的结果简单,计算量小。用于Solc滤波器消光比的研究,给出了在任意入射角下计算多块晶片Solc滤波器传输特性的一般表达式,对Solc滤波器锥光干涉图作了数值模拟。适用于计算各种类型双折射滤波器的离轴消光比。     

空气隙偏光镜对单模高斯光束光强分布影响的分析

根据光在格兰泰勒棱镜和格兰傅科棱镜空气隙胶合层中的干涉效应,分析了空气隙偏光棱镜对单模高斯光束光强分布的影响;结果表明:对于某一波长的入射光,当空气隙的厚度一定时,透射光强随光在空气隙介面上入射角的变化作周期性振荡;当入射角一定时,透射光强随空气隙厚度的变化作周期性变化;且透射高斯光束的形状也随光的入射角以及空气隙厚度的改变发生变化;且无论是透射光强的周期性振荡,还是透射高斯光束的形状的变化,格兰泰勒棱镜的影响均小于格兰傅科棱镜;这说明前者的综合性能优于后者。     

偏光棱镜调制器调制光强扰动的理论分析

以格兰-泰勒棱镜为例，根据实验现象对透射光强随旋转角扰动的原因进行了理论分析。实验中发现，透射光强曲线随着入射角的微小变化而偏离马吕斯定律，出现了周期性扰动。通过格兰-泰勒棱镜的单色偏振光束产生的干涉，再加上晶体-空气隙界面处反射比的因素，使得出射光强依赖于入射角。引入了扰动因子的概念，并系统讨论了扰动因子所造成的影响，从而得出了减小扰动的方法。理论研究结果与实验符合较好。为偏光棱镜的优化设计、生产及使用提供了理论基础。     

New Configuration of the Polarizationinsensitive Optical Circulator

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外应力对Y波导器件尾纤消光比的影响

本文研究了外应力对Y波导器件尾纤消光比及其温度稳定性的影响机理.在对保偏光纤固定部分进行应力分析的基础上,研究了外应力的大小、方向对于光纤应力双折射及尾纤消光比的影响,并分析了消光比的全温稳定性.结果表明,外应力是影响消光比常温性能及全温稳定性的主要因素.当外应力的方向与光纤固有应力双折射的主轴不重合时,尾纤最大消光比会低于保偏光纤的固有消光比,并且耦合后波导芯片与光纤慢轴之间对轴失准.当温度变化时,外应力的变化将导致消光比随温度的波动.当外应力沿着保偏光纤固有双折射主轴方向时,能够确保尾纤在耦合过程中实现最大的消光比,并保证波导芯片偏振方向与光纤慢轴的严格对准,此时尾纤消光比具有最佳的温度稳定性.对V型槽和U型槽光纤固定块进行了尾纤消光比性能及其温度稳定性的比较分析,试验验证表明,V型槽方案相对于难以保证外应力方向与光纤慢轴重合的U型槽固定块设计方案而言,可以有效改善消光比性能及其全温温度稳定性.     

可见光波段及1064nm波长处用于Glan-Taylor棱镜减反射膜

为了提高Glan-Taylor棱镜的透射率,研究了Glan-Taylor棱镜在可见光波段及1064nm波长处减反射膜膜的设计和制备．为提高薄膜和冰洲石晶体的附着力,采用沉积Al2O3为过渡层,ZrO2作缓冲层的方法,用单纯形优化的方法进行膜系优化设计．用电子束沉积和离子柬辅助沉积的方法制备了多层减反射膜,并采用石英晶体振荡法监控膜厚和沉积速率．测量结果表明,在可见光波段及1064nm波长处的剩余反射率均小于0．5％经测试薄膜与冰洲石晶体的附着力性能良好．     

可见光波段及1 064 nm波长处用于Glan-Taylor棱镜减反射膜

为了提高Glan-Taylor棱镜的透射率,研究了Glan-Taylor棱镜在可见光波段及1 064 nm波长处减反射膜膜的设计和制备.为提高薄膜和冰洲石晶体的附着力,采用沉积Al2O3为过渡层,ZrO2作缓冲层的方法,用单纯形优化的方法进行膜系优化设计.用电子束沉积和离子束辅助沉积的方法制备了多层减反射膜,并采用石英晶体振荡法监控膜厚和沉积速率.测量结果表明,在可见光波段及1 064 nm波长处的剩余反射率均小于0.5%经测试薄膜与冰洲石晶体的附着力性能良好.     

洛匈棱镜的正反向特性

给出了洛匈棱镜正、反向使用时分束角的精确表达式。从理论上证明,对任意合理的结构角及主折射率值来说,洛匈棱镜反向使用时的分束角小于正向使用时的分束角。研究了在锥光入射条件下洛匈棱镜中的e光和o光的传播方向、折射率、主平面、偏振方向等问题。证明了洛匈棱镜正向使用时第二块晶体中无偏折的光波只含有o光,参考圆圆周上各点光波的主平面相互平行,通过一个检偏器后可以实现消光;洛匈棱镜反向使用时,第二块晶体无偏折的光波同时包含了o光和e光,参考圆圆周上各点光波的主平面沿参考圆的径向,e光和o光的偏振方向分别沿径向和垂直于径向,通过检偏器后形成锥光干涉现象,不能消光。     

直角屋脊棱镜与立方角锥棱镜的光学特性

在光学工程应用方面,常利用棱镜对光路的折转作用,完成一定的转像、检测和测量等工作。在实际应用中,考虑到棱镜加工误差对光轴产生的影响,应用动态光学理论及推导公式,分别给出直角屋脊棱镜与立方角锥棱镜的作用矩阵、特征方向和极值轴向,得出2种棱镜光轴偏差的数学模型。根据实际加工误差,进一步推导出2棱镜的理论误差,并对2棱镜的理论误差进行比较。最后得出可以用直角屋脊棱镜代替立方角锥棱镜的结论。     

Cancellation of simple optical anisotropies without use of a Faraday mirror

We first derive the round-trip Jones matrix for double passage through a reciprocal optical medium by means of reflection off a plane mirror that could be optically anisotropic. We then show that if a medium with only linear birefringence and linear dichroism is placed between a pair of orthogonal quarter-wave plates with principal axes at 45 degrees to that of the medium and the sandwich is placed in front of an isotropic mirror it behaves, under double passage, like an isotropic medium. We describe a simple liquid crystal device that behaves, in reflection, as an isotropic medium whose refractive index can be varied by application of an electric field, thus acting as a phase only modulator for light in any polarization state.     

空气隙厚度对格兰-泰勒棱镜透射光强扰动影响的理论分析

以格兰–泰勒棱镜为例,根据实验现象对透射光强随旋转角扰动的原因进行了理论分析。通过泰勒棱镜的单色偏振光束在空气隙处发生多束光的干涉,使得透射光强依赖于入射角的大小。实验中棱镜振动引起入射角的微小扰动,导致了透射光强的扰动。着重分析了泰勒棱镜空气隙的厚度对于扰动的影响,并在此基础上讨论了减小扰动的方法,通过选取合适的空气隙厚度以及对棱镜的结构角做相应的调整可有效地减小扰动。