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复合式剪切差可调谐平行分束偏光镜 总被引:1,自引:0,他引:1
为了克服现有平行分束偏光镜剪切差较小且不可调谐的缺点,拓宽平行分束偏光镜的应用范围,采用冰洲石晶体和两块间距可调的三角形玻璃棱镜,制作出造价相对低廉、剪切差大范围内可调谐、且具有优越的分束比和透射比的复合式剪切差可调谐平行分束偏光镜。从理论上分析了该复合式棱镜的剪切差可调谐范围、e光和o光的分束比及未镀增透膜的情况下总的透射比随复合式棱镜中玻璃棱镜的结构角及两块玻璃棱镜的间距等结构参数的变化,并给出了仿真计算结果。依据该结果设计了实验样品,剪切差在1.4~50.2mm范围内可调谐,e光和o光的光强分束比优于1.1,且在未镀增透膜的情况下总的透射比大于80%。 相似文献
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为了既节省冰洲石晶体材料,又可以实现剪切差对入射点的连续可调,将光学玻璃(ZBaF3)与冰洲石结合,并用溴代萘胶合,设计了一种新型平行分束偏光镜.实验测试表明,棱镜出射的o光透射比高于85%,消光比优于10-5;e光透射比高于70%,消光比优于10-3.结果表明,该设计在节省冰洲石的前提下,不仅保持了良好性能,还实现性能创新,给使用带来便利,具有良好的应用前景. 相似文献
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频率差可调的加力型频率分裂氦氖激光器具有广阔的应用前景,目前鲜有关于该激光器频率差热漂移的具体报道,但它是一个重要的应用指标,特别是在光刻机用干涉仪中需要重点关注。采用弹性加力法对双折射-塞曼氦氖双频激光器进行频率差赋值,详细观察了频率差在开机漂变阶段、过渡阶段及稳定阶段状态的变化过程, 给出了频率差对开机时间的曲线。实验表明稳频作用下的频率差的稳定性优于23 kHz/h,重复性优于130 kHz。此外还就不同结构或材料的弹性加力元件对频率差的影响进行了对比分析,实验表明系统温度分布的均匀性和稳定性对频率差热漂移起重要作用。 相似文献
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本文提出了一种结合电润湿效应和静电力共同作用的可调偶次非球面液体透镜,利用Comsol Multiphysics软件对非球面液体透镜进行仿真研究,四圆环电极产生的静电力可以灵活地调整液体透镜的面型。利用该液体透镜设计了变焦光学系统,采用Zemax软件获得优化校正像差的非球面方程。作为可调偶次非球面液体透镜的目标面型,调整电润湿电极和四圆环电极上的电压,仿真得到的非球面与目标非球面间的光程均方根误差小于λ14,满足Marechal判据。在26~30 mm焦距范围内,与环形电极电压为0 V的液体透镜系统相比,环形电极施加调节电压的可调偶次非球面液体透镜变焦距系统有良好的成像效果。 相似文献
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Young‐Gi Kim Chang‐Woo Kim Seong‐Il Kim Byoung‐Gue Min Jong‐Min Lee Kyung Ho Lee 《ETRI Journal》2005,27(1):75-80
This paper addresses a fully‐integrated low phase noise X‐band oscillator fabricated using a carbon‐doped InGaP heterojunction bipolar transistor (HBT) GaAs process with a cutoff frequency of 53.2 GHz and maximum oscillation frequency of 70 GHz. The oscillator circuit consists of a negative resistance generating circuit with a base inductor, a resonating emitter circuit with a microstrip line, and a buffering resistive collector circuit with a tuning diode. The oscillator exhibits 4.33 dBm output power and achieves ?127.8 dBc/Hz phase noise at 100 kHz away from a 10.39 GHz oscillating frequency, which benchmarks the lowest reported phase noise achieved for a monolithic X‐band oscillator. The oscillator draws a 36 mA current from a 6.19 V supply with 47.1 MHz of frequency tuning range using a 4 V change. It occupies a 0.8 mm × 0.8 mm die area. 相似文献
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We study the delay performance of all-optical packet communication networks configured as ring and bus topologies employing cross-connect switches (or wavelength routers). Under a cross-connect network implementation, a packet experiences no (or minimal) internal queueing delays. Thus, the network can be implemented by high speed all-optical components. We further assume a packet-switched network operation, such as that using a slotted ring or bus access methods. In this case, a packet's delay is known before it is fed into the network. This can be used to determine if a packet must be dropped (when its end-to-end delay requirement is not met) at the time it accesses the network. It also leads to better utilization of network capacity resources. We also derive the delay performance for networks under a store-and-forward network operation. We show these implementations to yield very close average end-to-end packet queueing delay performance. We note that a cross-connect network operation can yield a somewhat higher queueing delay variance levels. However, the mean queueing delay for all traffic flows are the same for a cross-connect network operation (under equal nodal traffic loading), while that in a store-and-forward network increases as the path length increases. For a ring network loaded by a uniform traffic matrix, the queueing delay incurred by 90% of the packets in a cross-connect network may be lower than that experienced in a store-and-forward network. We also study a store-and-forward network operation under a nodal round robin (fair queueing) scheduling policy. We show the variance performance of the packet queueing delay for such a network to be close to that exhibited by a cross-connect (all-optical) network. 相似文献
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Le Jian Wang Cao Yang Jintao Zhang Hao Li Xingrui 《International Journal of Electronics》2018,105(11):1881-1899
A dynamic voltage restorer (DVR) can be installed in a middle-voltage (MV) power grid, to concurrently protect a cluster of sensitive loads from voltage sags. To further improve its efficiency and reduce the difficulty in its implementation, a novel control strategy for operating such a DVR as a virtual impedance in series with sensitive loads is proposed in this paper. In addition to its usual function of compensating for voltage sags, such a DVR can also operate as a virtual inductance, to function as a fault current limiter (FCL) during a downstream fault, or a virtual capacitance, to function as a series compensator (SC) to compensate the voltage loss along the feeder line during heavy load. Based on a dual-loop control design, strategies for operating a DVR as a series virtual inductance and a virtual capacitance are proposed, and methods for tuning the parameter values and a stability analysis of the whole system are presented. The feasibility and effectiveness of the proposed method are verified by simulations using the PSCAD software, and experimental results obtained using a prototype DVR are presented. 相似文献
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Optical and electrical characteristics of GaN vertical light emitting diode with current block layer
A GaN vertical light emitting diode(LED)with a current block layer(CBL)was investigated.Vertical LEDs without a CBL,with a non-ohmic contact CBL and with a silicon dioxide CBL were fabricated.Optical and electrical tests were carried out.The results show that the light output power of vertical LEDs with a non-ohmic contact CBL and with a silicon dioxide CBL are 40.6%and 60.7%higher than that of vertical LEDs without a CBL at 350 mA,respectively.The efficiencies of vertical LEDs without a CBL,with a non-ohmic contact CBL and with a silicon dioxide CBL drop to 72%,78%and 85.5%of their maximum efficiency at 350 mA,respectively. Moreover,vertical LEDs with a non-ohmic contact CBL have relatively superior anti-electrostatic ability. 相似文献
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Ian Glendinning Michael Nlle Christian Hausleitner Erwin Greilinger 《International Journal of Satellite Communications and Networking》2019,37(3):269-282
We describe a method for identifying the source of a satellite interferer using a single satellite. The technique relies on the fact that the strength of a carrier signal measured at the downlink station varies with time due to a number of factors, and we use a quantum‐inspired algorithm to compute a “signature” for a signal, which captures part of the pattern of variation that is a characteristic of the uplink antenna. We define a distance measure to numerically quantify the degree of similarity between two signatures, and by computing the distances between the signature for an interfering carrier and the signatures of the known carriers being relayed by the same satellite at the same time, we can identify the antenna that the interferer originated from, if a known carrier is being relayed from it. As a proof of concept, we evaluate the performance of the technique using a simple statistical model applied to measured carrier data. 相似文献
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传统地,MEMS红外探测器响应时间的测量需要基于黑体辐射源、斩波器、水冷装置等设备搭建一套复杂的测量系统,然而斩波器的遮挡区域和透光区域具有一定的面积,其按某频率工作时会消耗一定的时间,而测试所得的器件响应时间无法排除斩波器的工作耗时,导致测试结果存在较大误差,所测响应时间为14.46ms。为解决这一问题,提出了一种以钛宝石激光器为辐射光源,利用声光调制器构建纳秒级激光脉冲,MEMS红外探测器响应激光脉冲的作用输出脉冲电信号,很好地规避了测量系统中设备工作耗时引入的时间参数,所测响应时间仅为3.13ms。由此可见,传统方法中斩波器工作耗时引入的时间误差甚至超过器件响应时间的300%,充分证明了此方法可以有效解决这一问题,进而为MEMS红外探测器以及其它光学探测器性能参数的测试与计量提供了一种新的方法。 相似文献
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捷联惯性制导系统由于没有稳定的平台而需要通过大量的数学运算建立数学平台 ,因此制导对计算装置的性能要求很高。DSP芯片的出现为这种需要大量实时计算的制导系统提供了方便的应用方案。文中介绍了一种用DSP芯片设计的捷联惯性制导系统 ,给出了整个系统的电路和程序设计方法 相似文献
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Kamel Benachenhou Mhamed Hamadouche Abdelmalik Taleb‐Ahmed 《International Journal of Satellite Communications and Networking》2017,35(3):215-230
This paper deals with the analysis of the acquisition process performed by a global navigation satellite system (GNSS) receiver with a pilot and data channel or in case of GNSS hybrid receiver. Signal acquisition decides the presence or absence of GNSS signal by comparing signal under test with a fixed threshold and provides a code delay and a Doppler frequency estimation, but in low signal conditions or in a noisy environment; acquisition systems are vulnerable and can give a high false alarm and low detection probability. Firstly, we introduce a cell‐averaging‐constant false alarm rate (CFAR) then a data‐pilot cell‐averaging‐CFAR detector fusion based to deal with these situations. In this context, we use a new mathematical derivation to develop a closed‐form analytic expressions for the probabilities of detection and false alarm. The performances of the proposed detector are evaluated and compared with a non‐CFAR case through an analytical and numerical results validated by Mont Carlo simulations. Copyright © 2016 John Wiley & Sons, Ltd. 相似文献
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《Mechatronics》2014,24(8):1178-1188
This article presents the hybrid design and control of a quad-rotor system called Flymobile. Flymobile is a combined system of a mobile robot and a quad-rotor system aimed to perform both flying and driving tasks. Flymobile performs flying tasks in the same way as conventional quad-rotor systems while the tilting mechanism of each rotor allows Flymobile to navigate in its terrain for a driving task. The body frame with rotors is implemented by a calibration process through a test-bed equipped with a force sensor. The triangular wheel frame is designed to mimic motions of a mobile robot with three passive wheels. Sensor data of a gyro and an accelerometer are filtered and used for controlling the attitude of the system. Focusing on a practical approach of implementing a hybrid system, a non model-based approach is applied to control Flymobile. Experimental studies are demonstrated to show the feasibility of performing both driving and flying missions. 相似文献