共查询到19条相似文献,搜索用时 140 毫秒
1.
2.
3.
根据波动光学的理论,对菲涅耳近场衍射公式误差相位的影响进行了分析。以单缝衍射为例,讨论了误差相位与计算精度的联系。结合菲涅耳线波带片焦面光强分布的计算,对比了菲涅耳衍射公式与基尔霍夫衍射公式的计算结果,说明在不满足误差相位近似条件下使用菲涅耳衍射公式带来的影响。最后对影响波带片焦面光强分布的几个因素进行了讨论。 相似文献
4.
研究了基于菲涅耳相位透镜实现多平面全息投影的方法,采用硅基液晶相位调制器建立了多平面全息投影系统.首先,利用可编程菲涅耳相位透镜代替傅里叶透镜,将计算机生成的相位全息图与菲涅耳透镜的相位结合;其次,基于时分复用和空分复用原理提出了加载菲涅耳相位透镜与相位全息图到相位空间光调制器上的两种方法;最后,讨论了在多平面全息投影中每个单一平面实现旋转物体动态360°视角显示的方法.实验结果表明:在距离硅基液晶分别为500、800、1 100和1 400mm处的四个重构平面可以获得全息投影图像;通过动态地改变菲涅耳相位透镜的焦距,可以实现多平面全息投影. 相似文献
5.
大数值孔径衍射透镜的优化设计方法 总被引:4,自引:0,他引:4
本文针对大数值孔径衍射透镜工艺制作难的问题,以菲涅耳衍射透镜为例,研究了相位匹配原理并提出了一种优化设计二元大数值孔径衍射透镜的方法。在菲涅耳衍射透镜原理的基础上,确定了优化设计多相位台阶衍射透镜的结构参数,并给出了一个设计实例,最后对结果元件的衍射效率进行了分析与讨论。 相似文献
6.
7.
8.
应用反射型球面菲涅耳波带片的成像物镜设计 总被引:3,自引:0,他引:3
设计了一种应用球面菲涅耳波带反射面与非球面反射面结合的成像物镜。对球面结构的菲涅耳波带反射面进行分析,推导了球面菲涅耳波带反射面近似替代非球面的方法,采用单片球面菲涅耳波带反射面和三片非球面反射面设计成像物镜,在放大倍数100×、视场角120°、菲涅耳数2.5情况下,调制传递函数在放大成像侧可实现0.6 lp/mm的40%以上,畸变小于2.2%。该设计方法为菲涅耳波带片应用于可见光成像提供了参考,并随着菲涅耳器件加工技术的不断发展具有良好的应用前景。 相似文献
9.
10.
针对基于白光LED室内可见光无线光通信技术的应用需求, 设计了等齿距平面菲涅尔透镜. 相比常规透镜光接收天线, 菲涅尔透镜具有聚焦能力强、焦距短、透镜厚度薄、重量轻、成本低等优点. 利用Trace pro软件对设计进行了模拟仿真, 分析了透镜不同设计参数对接收天线光学增益、光学效率及光斑尺寸的影响, 讨论了透镜在平行光斜入射时的会聚情况. 结果表明, 平面点聚焦菲涅尔透镜的光学效率可达92.1%, 适用于小视场、高增益接收光学系统前端. 相似文献
11.
H. D. Hristov L. P. Kamburov R. Feick J. R. Urumov 《International Journal of Infrared and Millimeter Waves》2007,28(6):451-464
A millimeter wave antenna consisting of two Fresnel zone plate lenses, plane and conical, is examined numerically by use of
the vector diffraction theory. The lenses are of Wood-Wiltse (double-dielectric) or Soret (half-open) type, and are designed
for the frequency of 117 GHz. The lenses are made conformal to a truncated circular cone with a base diameter of 500 mm and
a plateau diameter of 250 mm. Designs for two opening semi-angles, 45° and 75° each of them with a particular lens thickness
are presented. For the angle of 90° the cone lens becomes a plane ring lens, which in combination with the plateau zone lens
forms a plane lens of size equal to the cone base diameter. Illuminated by directive feeds set at a focal distance of 525 mm
from the cone apex, the double-dielectric and half-open compound and plane lenses, form three pairs of Fresnel zone lens antennas,
the co-polar and cross-polar radiation characteristics of which have been compared numerically. The double-dielectric lens
antennas examined are about 5 dB superior in gain to the half-open lens antennas, which has a gain of approximately 45 dBi.
Because all lenses are of equal transverse aperture, the corresponding lens antennas exhibit the same −3 dB beamwidth of about
0.33 degrees. The plane zone lens antenna is very thin and simple. Instead, the antenna comprising a 3-D compound Fresnel
zone lens is thicker but can be made conformal to a specific surface shape and possesses more levels of design and optimization
freedom. 相似文献
12.
13.
The imaging principle of Fresnel zone plate and photon sieve were analyzed in this paper. The design and fabrication of phase photon sieve were discussed. The feasibility of using phase photon sieve to realize nano-lithography was analyzed, a novel lithography experiment system based on phase photon sieve was presented, which not only has higher resolution and image contrast than the Fresnel zone plate lithography but also have higher diffractive efficiency than the amplitude photon sieve lithography. 相似文献
14.
We propose a method to improve the resolution of near-field optical system with a solid immersion lens by using a multiphase level Fresnel zone plate. The analyses are based on scalar angular spectrum theory. The results show that the multiphase Fresnel zone plate can not only decrease the spot size but also decrease the sidelobe intensity and enhance greatly the diffractive efficiency compared with annular amplitude filter or binary 2-, 3-, 4-zone phase filter. 相似文献
15.
为满足星间激光通信对高隔离水平光学天线的要求,实现对光学天线隔离度的仿真分析和优化,提出了一种将红外系统冷反射的特征控制量YNI值作为衡量光学元件表面后向反射能量强度,并控制光学天线优化以提高隔离度水平的方法。在Light Tools软件中为某激光通信终端的卡塞格林天线创建了实体模型,通过仿真分析得出了各元件表面的后向反射率。在ZEMAX软件中以增大各元件表面的YNI值为目标优化天线结构。对比优化前后的结果,系统的后向反射率从3.068 8×10~(-4)减小到1.075 5×10~(-5),隔离度从-35.13 d B减小到-49.68 d B。优化后的卡塞格林天线具备较高的隔离度水平,可用于星间激光通信。 相似文献
16.
为了减小馈线损耗和方便天线旋转,设计了超宽带Cassegrain双反射面天线系统。采用FEKO数值模拟软件在0.2~1.5 GHz频率范围内模拟了不同副反射面直径的4.5 m双反射面天线(焦径比为0.4)的辐射增益,并与相同口径和焦径比的前馈式反射面天线进行了比较。模拟结果表明:当双曲副反射面直径为70 cm,焦距为22.5 cm时,在0.2~1.0 GHz频率范围内,双反射面天线增益比前馈式抛物面天线高1~2 dB;在1.1~1.5 GHz频率范围内,双反射面天线增益比前馈式抛物面天线小1~2 dB。选择直径为70 cm、焦距为22.5 cm的双曲副面与TEM喇叭和4.5 m抛物面组成双反射面天线系统,分别用960 ps和3 ns脉宽的单极脉冲源对天线进行了实验研究。实验结果表明:用960 ps和3 ns脉宽的单极脉冲激励,Cassegrain双反射面天线在70 m轴上远场辐射场波形峰峰值分别为前馈式反射面天线的158%和162%。 相似文献
17.
Based on the Kirchhoff-Huygens diffraction theory, a simple analytical method of a planar folded Fresnel zone-plate (FZP), that is the case when a planar reflector is placed behind the zone plates, has been developed. According to the numerical calculation results, the design procedure of the FZP antenna has been presented, and its focusing characteristics and gain-optimized conditions have been discussed. The variations of the focal field distribution with the antenna parameters such as zone numbers, focal length and antenna diameter and the radiation power patterns of the FZP have been simulated numerically. To take a good balance of both receiving and transmitting antennas, at 60GHz operating frequency, the focal length should be designed as a half of the antenna diameter and the zone number should be from 10 to 15. The results in this work show that the folded FZP has good focal characteristics and off-axis performance, and its antenna gain can be optimized by the suitable antenna parameter design. The possibility of applying the folded FZP as a low cost and high gain antenna without strict manufacturing requirement for millimeter-wave communications has been shown. 相似文献
18.
高强度辐射场构建系统是对多种武器进行电磁辐照效应试验的关键装备,其要求在距天线一定距离的区域内产生高强度且尽量均匀分布的电磁场。本文设计了一款适用于该系统的X波段偏置卡塞格伦多模反射面天线。用反射面天线是为了获得尽可能高的增益,使期望区域内的场强尽可能大;用多模反射面理论实现了窄波束的平顶赋形,使期望区域内的场趋于均匀分布,区域外的场迅速减小。实测结果表明天线增益大于29.8 dB,3 dB波束宽度不小于4.6°,在此范围内方向图幅度起伏小于2 dB,平顶特性明显。此外,偏置的反射面天线还有馈源遮挡小、馈线损耗低和易于折叠收藏等优点,可以很好的应用于电磁环境模拟试验设备中。 相似文献
19.
设计了具有抛物面结构的卡塞格伦光学天线.通过对偏轴下的卡塞格伦光学天线系统的分析,得到了不同偏转角所对应的接收光斑面积表达式和功率衰减曲线.讨论了偏轴下的接收天线增益与波长及偏转角的关系,仿真出在偏轴与轴对准两种情形下的增益曲线.仿真结果表明,〖JP2〗最大偏轴比轴对准情形增益降低了6.564dB.最后分别针对轴对准与某种偏轴情形下的系统做了光斑测试实验与天线耦合效率测试实验.结果为:偏轴下天线耦合效率降低了26.966%.这些研究为星间光通信中控制系统实现光轴的精确对准提供了理论依据,具有重要的实用价值
关键词:
偏轴
卡塞格伦光学天线
偏转角
增益 相似文献