共查询到20条相似文献,搜索用时 140 毫秒
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光学系统温度效应分析和无热化设计 总被引:1,自引:0,他引:1
建立了用于温度效应分析的光学系统热模型,提出了一种光学机械综合优化的被动补偿方法.该方法将光学系统中光学元件和相关机械零件温度特性统一参与光学系统优化设汁.保证在较大的温度范围内都可以有很好的成像质量.设计实例表明,采用这个方法可以在不增加光学和机械结构复杂度的情况下得到良好的光机被动无热化效果. 相似文献
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红外成像光学系统无热化设计 总被引:1,自引:0,他引:1
红外成像光学系统受温度变化的影响非常明显,所以必须进行无热化设计.分析了温度变化对红外成像光学系统的影响,根据无热化设计技术设计一个能满足-40℃~80℃宽温度范围的红外成像系统.通过比较机械补偿法和光学补偿法两种无热化补偿技术,可以看出光学补偿法具有明显的优点. 相似文献
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红外光学系统无热化设计研究 总被引:1,自引:0,他引:1
分析了温度对红外光学系统的影响。军用红外光学系统往往工作在温度变化较大的环境中,因此必须采取有效的温度补偿措施以减少离焦。介绍了红外光学系统无热化设计的方法及原理。根据小型红外光学系统的设计参数,提出了光学被动式无热化设计思路。试验结果表明,光学系统在0~60℃范围内可保持良好的成像效果。 相似文献
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无热技术在光学系统中的应用 总被引:4,自引:3,他引:1
围绕环境温度对光学系统性能的影响及其解决方法.分析了温度效应的三个方面的因素:光学元件的折射率、曲率半径和中心厚度以及光学元件之间的空气间隔,并讨论了这三个因素与温度变化之间的关系。提出使用无热设计来消除温度效应对光学系统的影响.并且比较了当前三种无热技术之间的优缺点。最后给出了一个红外光学系统作为例子予以分析,在设计过程中使用了机械主动式无热技术,以补偿温度变化所产生的影响,通过比较使用无热设计前后系统的成像质量.说明了无热设计可以消除光学系统中温度效应的影响,使系统在较大的温度范围内保持较好的成像质量。 相似文献
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由于温度变化会导致红外光学系统的成像质量变坏,因此,对于工作环境温度在-45~60℃之间的长波红外折射光学系统来说,无热化设计成为光学系统设计的难点和关键.为研究不同的无热化补偿方式的特点,分别设计了基于光学被动式无热化补偿和基于机械被动式无热化补偿的两种长波红外非制冷光学系统,对比分析了两种光学系统的优缺点,给出了选择无热化补偿方法的基本原则. 相似文献
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A calibration system aiming for automatically correcting the effect of process variation on performance of on-chip Active Inductor Band Pass Filter (AIBPF) is presented. The benefit of using active inductors to build on-chip band pass filter is less chip area consumption and the tunability of center frequency compared to designs employing passive inductors. However, the fatal drawback of active inductor is performance degradation caused by process variation generated during chip fabrication. The proposed calibration system has the ability to detect process variation and adjust the AIBPF center frequency back to the designed 5.2 GHz by compensating the bias voltage. Simulation results show this calibration system can significantly improve the yield of circuits employing AIBPFs. 相似文献
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对于工作环境温度在-40~60℃之间的长波红外折射光学系统来说,由于红外光学材料受温度变化影响非常大,光学系统必须进行无热化设计。在介绍了无热化系统的种类,分析了温度变化对红外光学系统的影响基础之上,基于非制冷型焦平面探测器,设计了工作在长波红外8~12 m,F#为2,视场角为6.8的摄远型物镜系统。采用添加棱镜的方法,使系统在不添加特殊面型的情况下达到无热化的目的,同时使系统结构紧凑,摄远比达到0.69。透镜面型均为标准球面,利于加工、装调、检测。设计结果表明,光学系统的调制传递函数在每个规定温度下均能接近衍射极限,满足了设计要求。 相似文献
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Performance analysis and test for passive radio frequency identification (RFID) system at ultra high frequency (UHF) band in free space and line-of-sight (LOS) indoor environments are conducted in this article. Performance degradation of different materials is presented, in terms of power received by tag and reader, communication range and link information rates, etc. Particularly, the multipath fading and root mean square (RMS) delay spread in LOS indoor environments are analyzed by a 5-ray model with different polarization, such as horizontal polarization, vertical polarization and circular polarization. A practical test is carried out on an indoor balcony of an office building. In addition, the electric field environment is simulated to analyze multipath degradation using the tool of Ansoft HFSS. According to the test, the recognition rate is almost consistent with the results of theoretical analysis and simulation. The small scale fading and the field nulls are observed. The multipath degradation significantly affects the passive RFID system on communication range and recognition rate, and it is also one of the key limitations on system performance. The variations of power in multipath environments can also influence the information rates, while the rates are still enough for available standard and applications at short range. 相似文献
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总结了红外温度自适应光学系统的实现方式,理论分析了机械补偿法的设计过程,研制了一种机械补偿式红外温度自适应光机系统。其光学指标焦距f=50 mm,相对孔径1/1.2,适配长波非制冷红外焦平面探测器,其像素为640×480,像元大小17 m,工作温度:―40℃~+80℃。设计结果表明,各个温度参考点各个参考视场的弥散斑半径均小于系统艾里斑,并且像面照度均匀。在空间频率20 lp/mm处,光学系统的调制传递函数接近衍射极限。利用机械补偿方式实现了系统各项技术指标。 相似文献
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Dong Ku Kim Jung Min Park Myoung Seob Lim 《Electronics letters》1997,33(9):733-735
Using simulations, the authors evaluate the performance of the vestigial sideband QPSK modulated wideband CDMA (VSB/QPSK/W-CDMA) system. A VSB system is used to increase the spectrum efficiency by 30% compared to the conventional double sideband (DSB) system. The VSB/QPSK/W-CDMA scheme showed a comparable performance to the DSB/QPSK/W-CDMA scheme in the frequency flat fading channel. However, the VSB system showed an inferior performance in the presence of multipath fading and multiple access interference. It was shown that the use of additional Rake branches is effective in compensating for the VSB system's performance degradation 相似文献
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During the long coherent integration time in passive radar,the motion parameters (such as high speed,acceleration and jerk motion,etc.) will bring about range migration (RM) and Doppler frequency migration (DFM),further deteriorate the integration performance.To realize the coherent integration of maneuvering targets with jerk motion,a method based on frequency reversing transform (FRT) and modified Lv’s distribution (MLVD) called FRT-MLVD was proposed to achieve the coherent integration and motion parameters estimation.More specifically,the FRT was firstly proposed to remove RM.Then the MLVD was employed to estimate the acceleration and jerk parameters.After compensating the DFM induced by the acceleration and jerk motion,the residual RM was corrected and the velocity and range was achieved via the KT operation.Simulation results demonstrate that the proposed method can effectively compensate the RM and DFM induced by the target motion parameters in passive radar,and for maneuvering targets with jerk motion,the proposed method achieves a better integration and detection performance over existing methods. 相似文献
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提出了一种采用基于光学相位分集接收技术实现远程相干光正交频分复用(CO-OFDM)信号的远程光接入方案,并进行了理论研究和仿真验证。在本方案中,没有使用色散补偿光纤(DCF)或者色散补偿模块(DCM)补偿光纤信道色散导致的负面效应,原因是CO-OFDM信号能有效抵抗传输过程中色度色散(CD)和偏振模色散(PMD)引起的负面效应。仿真结果表明,10Gbit/s CO-OOFDM信号在标准单模光纤(SMF-28)传输320km后,采用相位估计技术得到的OFDM电信号,其时域波形的相位抖动幅度更小;与采用光载波自提取技术接收相位调制COOFDM的方案进行比较,测试误差向量幅度(EVM)的结果表明,本文方案可以获得更好的COOFDM信号接收性能,星座图中星座点收敛更加紧凑,接收的CO-OFDM信号质量更高。 相似文献