Study of the Induced Birefringence in the Single-mode Optic Fiber

单模光纤在通常情况下可以认为是不存在双折射现象的。但当光纤受到弯曲、侧压及扭转时 ,由于光弹效应使得光纤分别产生了线性双折射和圆振双折射。该文对单模光纤由于各种作用产生的诱导双折射进行了论述 ,推导了不同情况下双折射的计算公式 ,并分析了其中的差别。同时 ,还初步分析了实际系统中对各种双折射效应的应用。In a general way, it is considered that the single-mode optic fiber has no birefringence. But once the single-mode optic fiber is bent, clamped or twisted, the externally applied stresses can lead to induced birefringences through the photoelastic effect. This paper discusses the induced birefringences, one kind of which is linear birefringence, induced by bending or lamping the fiber, while another is circular birefringence, induced by twisting the fiber. Based on the photoelastic effect, the formulas in different conditions are presented. Furthermore, the applications of those formulas in real system are mentioned

Study on Laser Triangulation Method Measurement

三角法属于主动视觉测量方法,是非接触光学测量的一个重要形式。传统的光学三角法,改之以激光光源,并结合电子信号分析电路和计算机信号处理,使测量系统可以得到较高的精度,在三维形貌测量及其他应用中已有一定的研究并有相当的前景。该文较系统地分析了不同结构、不同类型的激光三角测量系统,并比较了其优缺点。针对实际应用中出现的对测量精度的影响因素,给出了相应的解决办法。Triangulation measurement is initiative and non-contact.With the laser as lamp-house,electronic signal analyzing circuit and computer signal disposal,the triangulation measurement can achieve the higher precision,which is needed in many applications,such as three-dimension measurement,and has equivalent foreground.Laser triangulation systems with different structures and different sorts are introduced respectively and their characteristics are compared.Infective factors on precision in practice applications are discussed and the corresponding solutions

Beam transformation in laser processing

激光光束形状和能量分布直接限定了激光加工的应用。为满足不同的激光加工要求,必须对激光光束进行光束变换。应用旋转棱镜和组合光学系统能够实现实心和环状光束之间的相互变换。从几何光学角度对旋转棱镜组合光学系统进行了理论分析和实验。通过调整正负旋转棱镜的间距d,获取不同形状和能量分布的激光光束。实验结果表明,基于旋转棱镜组合光学系统的光束变换技术,有效地实现了多种形式的光束变换,提高了激光束的利用率,在激光加工领域中具有广泛的应用前景。The shape and quality of laser beam directly define its applications in the laser processing.For different requests of laser processing,the input beam always needs to be transformed.The transformation between the solid beam and annular beam can be realized by the axicon-based optical devices.The optical system is analyzed based on the geometry optical theory.By adjusting the separation of the positive and negative axicon,different shapes and the energy distributions are gained.It is shown that the axicon-based beam transformations raise the use factor of laser and have wide application prospect in laser processing field.福建省科学技术厅资助项目(2005HZ1020

Experimental System of Optic Fiber Pressure Sensor Based on Photoelastic Effect

光纤具有很高的弹性模量和质量系数，其应力-应变在一个相当大范围内的成线性关系，没有诸如蠕变和时间-边缘效应缺陷，对正常变化的湿度、温度反应较不灵敏，因此以光纤作为传感元件的光纤压力传感器不但具有光纤传感器普遍具有的灵敏度高、响应速度快、抗电磁干扰、耐腐蚀、体积小、结构简单的优点，更在长时期压力测量方面有着相当的优越性。 本文通过对光弹效应及光纤双折射和偏振特性进行研究，使用高双折射保偏光纤设计并实现了基于光弹效应的光纤压力传感器实验系统，对该系统进行了压力测试。其主要研究工作如下： ①基于光弹效应原理，分析光纤双折射现象和偏振特性，考虑在实验过程中各种可能出现的光纤微扰，给出了光纤中各受力...The fiber, sensor element of the fiber optic pressure sensor, which has prevalent virtues of the fiber optic sensors: high sensitivity, quick responsibility, immunity to EMI, corrosion resistance, small volume and simple structure, reveals its superiority in the aspects of long-term pressure measuring, because of its quite high modulus of elastic and coefficient of mass, which provide the linear f...学位：工学硕士院系专业：物理与机电工程学院机电工程系_测试计量技术及仪器学号：20012901

Infrared focus plane array used in infrared thermal imaging technology

微机电系统(MEMS)推动了红外焦平面阵列(FPA)技术的发展,使红外热像仪的性能和精度得到了很大的提高。红外焦平面阵列按照其工作原理、结构形式、制冷方式和成像方式的不同分为各种类型,比较并分析了各类型红外焦平面阵列间的不同点和各自特点。着重介绍了红外焦平面阵列技术最新研究热点中的光量子类红外焦平面阵列和双色、多色红外焦平面阵列,以及近些年它们在国内外最新的研究成果。最后讨论了红外焦平面阵列技术的发展趋势。As micro-electromechanical systems (MEMS) promotion infrared focal plane array (FPA) technology development,thermal imaging performance and accuracy have been greatly improved.The infrared focus plane array with different principle,structures,refrigeration mode and imaging mode are summarized briefly and compared in this paper,and the world-wide up-to-date investigations in hotspots of infrared focus plane array are present,focusing on photons quantum wells IRFPA,dual-band IRFPA and multi-band IRFPA

灰雁繁殖期的行为日节律及时间分配

2011年4～6月,采用瞬时扫描法对徐州睢宁金桥禽业发展有限公司2对繁殖良好的灰雁的繁殖行为时间分配和活动节律进行研究,采用非参数检验的Kruskal-Wallis H法分析不同性别灰雁繁殖前中后期行为的性别差异,以及相同性别的灰雁在繁殖的不同时期的行为差异。结果显示:灰雁在采食、理羽、静立、趴卧、孵化等行为上存在着明显的节律性。取食行为多发生在上午和下午的中间时段,孵化多在早晨和傍晚,而中午的大部分时间处于休息状态。孵化期内雌雄个体的行为差异很大,灰雁繁殖时期各种行为所占的比例不仅存在着一定的性别差异,而且同一性别个体在不同的繁殖阶段各种行为所占的比例也有很大变化

复合光学微球腔回音壁模共振谱选模特性分析

提出一种新型的基于复合微球腔WGM（回音壁模式）共振谱的全光纤激光腔内选模方法。通过多层介质和并联结构构造复合光学微球腔,基于FDTD（有限差分时域）算法仿真并分析了复合微球腔内WGM的光场分布特性。基于复合光学微球腔-拉锥光纤的最佳耦合条件,计算得到其传输透射谱。通过优化复合微球腔的参数并改进耦合条件,实现了WGM共振谱带宽的压缩和边模抑制比的提高。所获得的窄带透射谱对实现全光纤激光选模具有重要意义

Effects of Cr(Ⅲ) Stress on Activities and Isozymes of SOD and POD of Kandelia candel Mangrove Seedlings

砂基栽培红树植物秋茄(Kandeliacandel)幼苗60d,研究重金属Cr(Ⅲ)不同暴污强度(0~300mg/L)的环境胁迫下,对秋茄幼苗根系及叶片超氧化物歧化酶(SOD)、过氧化物酶(POD)活性的影响以及其同工酶谱的变化.结果表明:随着Cr(Ⅲ)浓度的提高,秋茄幼苗根系及叶片SOD活性均表现为先上升后下降的变化趋势,并均高于对照,其中根系SOD持最高活性的Cr浓度在25~50mg/L,叶片在10mg/L左右.受Cr(Ⅲ)胁迫,秋茄幼苗根系POD活性普遍明显高于对照,而叶片POD活性则明显低于对照.在有效防御Cr胁迫伤害方面,根系比叶片具有更大的耐受性,POD活性对Cr的敏感性大于SOD.受Cr(Ⅲ)的胁迫,秋茄幼苗根系或叶片SOD和POD活性的变化与同工酶的谱带数量和强弱的变化密切相关.In this paper,mangrove Kandelia candel hypocotyls were cultivated by sand culture and treated for 60 days in a greenhouse under natural light conditions.The influence of increasing concentration of Cr(Ⅲ) (0,10,25,50,100,150,200,300 mg/L) on the activities and isozymes of SOD and POD of mangrove K.candel seedlings was studied.The results showed that activities of SOD and POD in roots of mangrove K.candel seedlings all increased compared to the control under the Cr(Ⅲ) stress conditions.The SOD activities in roots and leaves firstly increased and then decreased with increasing concentration of Cr(Ⅲ) and their efficacious recoveries separately occurred in the conditions that Cr(Ⅲ) concentrations were about 50 mg/L and 10 mg/L.Under the Cr(Ⅲ) stress conditions,the activitiy of POD in roots increased compared to the control but the activitiy of POD in leaves obviously declined.The roots had more tolerance than the leaves did on the Cr(Ⅲ) stress and the POD activity was more sensitive than the SOD activity.Moreover,the study showed that the changes of the SOD and POD activities in roots and leaves were caused by the according variances of the SOD and POD isozymes

黑天鹅孵化期行为时间分配

2011年1～2月,采用瞬时扫描法对徐州金桥珍禽养殖场的黑天鹅进行了研究。研究发现,黑天鹅在孵化期具有一定的行为时间分配。行为时间分配为:孵化29.96%、理羽15.06%、采食11.87%、游泳10.22%、站立8.09%、游走7.15%、筑巢7.07%、警戒6.09%、休息3.00%、对鸣1.53%。对不同性别黑天鹅的时间分配进行独立样本T检验,结果显示:除筑巢行为差异显著（P<0.05）,孵化、采食、休息、游泳行为上差异极显著（P<0.01）外,其他行为差异不显著