共查询到17条相似文献,搜索用时 62 毫秒
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铁电180°畴结构在超声波作用下将被诱导出沿畴壁传播的铁电畴层波,其电场导致了构成铁电180°畴结构的晶体的电光效应,畴结构的光率体发生了改变,晶体的主折射率受到激发铁电畴层波的超声波的调节。这一效应在声光控制和超声检测方面有应用价值。 相似文献
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中空光束具有特殊的物理性质,在光信息处理、微电子学、同位素分离和分子光学等领域有着广泛的应用。本文提出采用TFT—LCD制作相位型菲涅尔波带片,平面波经TFTLCD衍射生成中空光束。实验结果表明,基于TFT—LCD的菲涅尔波带片生成的中空光束具有实时可调、快捷和精确等优点。 相似文献
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液晶菲涅尔波带透镜是基于液晶的电光效应来改变其折射率分布的新型透镜。在频率为100 Hz的交流电压驱动下,用UV-Vis 8500型紫外/可见分光光度计测量了液晶菲涅尔波带透镜三基色R(700.0 nm)、G(546.1 nm)、B(435.8 nm)的电光特性,得到三基色的T-V曲线。分别在0 V、1.0 V、3.0 V下,测量He-Ne激光通过液晶菲涅尔波带透镜后的光强,得到光强分布。结果表明,液晶菲涅尔波带透镜的阈值电压为1.0 V,且随着电压的改变,三基色透过率的变化趋势是一致的。同一波长的入射光在不同电压下通过透镜后,透镜的焦距不同。 相似文献
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空心高斯光束是一种不携带轨道角动量的空心光束,它的暗斑尺寸较小,函数公式简单,在原子引导、粒子操控、光通信等领域具有潜在应用价值。近年来,关于波带片的研究不断深入,通过使用等效光瞳函数理论,说明了波带片的焦平面复振幅分布函数正比于其等效光瞳函数的傅里叶-贝塞尔变换,可以通过此关系设计产生空心高斯光束的波带片。作为一个应用,分别计算了用来产生一阶、三阶、六阶空心高斯光束的波带片的等效光瞳函数,据此设计了这三个波带片的结构参数,并研究了改变波长和焦距对波带片结构参数和暗斑尺寸的影响。基于瑞利-索末菲衍射积分对这三个改进型菲涅耳波带片的焦平面光场进行仿真模拟,仿真结果与预期相符,验证了使用等效光瞳函数法设计波带片的可靠性和精确性。 相似文献
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用矢量Rayleigh-Sommerfeld(VRS)衍射理论分析计算了高数值孔径多台阶相幅型菲涅耳波带片(M-SHFZP)的聚焦场分布。当线性偏振光垂直入射到M-SHFZP,结果显示:1)由于薄膜透射率随着刻蚀台阶深度发生变化,致使实际的M-SHFZP的聚焦强度小于多台阶纯相位型菲涅耳波带片(M-SPFZP)的聚焦强度,但是M-SHFZP的聚焦光斑大小基本上与M-SPFZP的相同;2)聚焦光的强度随着台阶数的增加而增加,但聚焦光斑的大小不随台阶数变化;3)对于低数值孔径的M-SHFZP,光轴上的强度呈现一个多焦点分布,但是对于高数值孔径的M-SHFZP,高级焦点的强度被大大抑制。台阶数愈多,数值孔径愈大,抑制高级次焦点的能力愈强。VRS矢量衍射理论的计算结果与时域有限差分法(FDTD)模拟结果基本一致。 相似文献
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铁电180°畴结构在超声波作用下将被诱导出沿畴壁传播的铁电畴层波,其应变场导致了构成铁电180°畴结构的晶体的弹光效应,畴结构的光率体发生了改变,晶体的主折射率和双折射率受到激发铁电畴层波的超声波的调制,这一现象在声光控制和超声检测方面有应用价值。 相似文献
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Y. J. Guo S. K. Barton 《International Journal of Satellite Communications and Networking》1994,12(4):381-385
The theory of offset Fresnel zone plate antennas is presented. Explicit formulae for the design of the zone boundaries for the offset Fresnel zone plate are given. Theorectical equations and numerical results for the far-field analysis are presented. It is found that when the offset angle increases, the zone boundaries become more elliptic and the plate becomes more asymmetric in the E-plane. With the number of full wave zones and the plate width in the W-plane fixed, the plate width in the E-plane increases with the offset angle, which keeps the projected aperture area constant. Within a limited range of offset angles, the offset configuration can be employed without degrading the radiation performance much. For large offset angles, however, the asymmetry of the configuration may lead to increased sidelobes and decreased antenna directivity. An experiment with one particular phase reversal zone plate antenna with 30° offset angle shows good agreement between the measured antenna pattern and the theoretical prediction. 相似文献
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An objective lens composed of a spherical Fresnel zone plate mirror and aspheric mirrors is designed.The Fresnel zone plate with a spherical shape is analyzed, and the method to approximately replace the aspherical mirror with spherical Fresnel zone plate is deduced. The objective lens is designed with a single spherical Fresnel zone plate mirror and three aspherical mirrors. Under the condition of 100 × magnification,2.5 Fresnel number and 120° field angle, the modulation transfer function can reach above 40% at 0.6 line pairs/mm on the magnification side, and the distortion is less than 2.2%. This method can provide a reference for the application of Fresnel zone plate in visible light imaging, and has a bright future with the continuous development of the fabrication technique of Fresnel devices. 相似文献
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Y. J. Guo S. K. Barton 《International Journal of Satellite Communications and Networking》1993,11(2):75-80
Owing to its flat nature and light weight etc., the Fresnel zone plate antenna is becoming very attractive for such applications as DBS reception and receive-only VSAT. The disadvantages of low efficiency and high sidelobes of the simple and the phase reversing zone plates can be improved by using phase correcting techniques. In this paper, a systematic investigation on the efficiency and sidelobe performance of subzone phase correcting zone plate antennas is presented. The design of a form of multilayer phase correcting zone plate reflector is described. A quarter-wave zone plate reflector constructed with three dielectric layers and metallized rings is reported, with measured peak efficiency of 55 per cent. 相似文献
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