Al_2O_3∶Fe~(3+)体系晶格局域结构的EPR理论研究

本文通过分析Al2 O3 ∶Fe3 + 体系中Fe3 + 离子的EPR谱 ,研究Fe3 + 的局域晶体结构结果表明Al2 O3 ∶Fe3 + 的局域结构存在各向异性膨胀。用拟合EPR谱的低对称参量D和 (a -F)实验值的方法 ,求得两个三棱锥的棱与C3 轴的夹角分别为θ1=4 6 .5 4°和θ2 =6 1.2 6° ,相对于原Al2 O3 结构的畸变角分别是Δθ1=- 1.1°± 0 .1° ,Δθ2 =- 1.8°。两畸变角同时均小于 0说明Al2 O3 ∶Fe3 + 体系中含Fe3 + 离子的晶格主要产生沿C3 轴的伸长畸变     

AWG中波导间耦合造成的相位畸变的分析

用(1,1)阶Pad啨近似的广角BPM计算了阵列波导光栅(AWG)中由于阵列波导间耦合造成的相位畸变以及由于相位畸变引起的相位误差分别考虑了光从中心/非中心输入波导入射两种情况结果表明,波导间的耦合会造成显著的相位畸变,但由此引起的相位误差却很小,光从中心输入波导入射时对应的相位误差10-3rad,从非中心输入波导入射时的相位误差约为10-2rad针对波导阵列边缘效应引起的相位畸变,设计AWG结构时,在阵列部分两侧增加了边缘辅助波导结构,从而消除了边缘效应,使得边缘阵列波导对应的相位误差从10-1rad量级减小为10-3(10-2)rad量级.     

Expressions for third-order aberration theory for holographic images

Expressions for third-order aberration in the reconstructed wave front of point objects are established by Meier. But Smith, Neil Mohon, Sweatt independently reported that their results differ from that of Meier. We found that coefficients for spherical aberration, astigmatism, tally with Meier’s while coefficients for distortion and coma differ.     

Analysis of Blocking Effect for MM-Wave Receiver

In this paper, the blocking effect that takes place in MM-wave receiver is analyzed; the methods that prevent and avoid the blocking effect are put forward. The results analyzed and the methods put forward possess certain useful significance for many MM-wave receivers in which the RF amplifiers are contained at present.     

Wavefront reconstruction using iterative discrete Fourier transforms with Fried geometry

A new kind of wavefront reconstruction algorithm is proposed in this paper, which can estimate the wavefront from its orthogonal gradients at different sample points. We model the gradients measured by wavefront sensor with the Fried geometry. Iterative discrete Fourier transforms and the correspondent Fried inverse filter in spatial frequency domain are introduced. No special boundary control is required to process the boundary condition in this algorithm. The stimulation and the experimental results show that the new algorithm has strong capability to fit the wavefront and it is more available if the sample points are few.     

热晕效应相位补偿定标参量的数值分析

利用数值模拟的方法，对三种不同发射口径情况下准直强激光水平传输稳态热晕效应的自适应光学相位补偿进行了计算。结果表明，定标参量ND／NFB可充分描述其相位补偿的效果，且对理想柔形镜及实际自适应光学系统相位补偿而言，其不稳定性定标参量的阈值分别为6.0、0.35。当ND／NFB于阈值时，相位补偿效果理想且随ND／NFB的改变Strehl比变化平缓；而当ND/NFB大于阈值时，由于相位补偿不稳定性的增强，补偿效果迅速变差。     

Intraocular lens design for treating high myopia based on individual eye model

In this research, we firstly design the phakic intraocular lens (PIOL) based on individual eye model with optical design software ZEMAX. The individual PIOL is designed to correct the defocus and astigmatism, and then we compare the PIOL power calculated from the individual eye model with that from the experiential formula. Close values of PIOL power are obtained between the individual eye model and the formula, but the suggested method has more accuracy with more functions. The impact of PIOL decentration on human eye is evaluated, including rotation decentration, flat axis decentration, steep axis decentration and axial movement of PIOL, which is impossible with traditional method. To control the PIOL decentration errors, we give the limit values of PIOL decentration for the specific eye in this study.     

图像显示系统几何畸变的测量及校正

为了保证图像显示系统能够产生120°的大视场,在系统中使用了超广角耦合物镜,这样就不可避免地存在几何畸变。提出了一种基于点物成像原理,并采用数码相机和精密单轴转台进行畸变测量的方法,介绍了测量原理和测量过程,根据测量后得到的畸变规律,采用数字图像处理的方法对几何畸变进行了校正。校正后,图像显示系统的畸变小于0.4%,完全能够满足导弹景象匹配系统定位误差及定位概率的检测要求。     

Nonlinear Frequency-Modulation Distortion Analysis for VCO Based on Harmonic Balance Method

The analysis methods for the steady-state responses of the voltage tuning negative resistance oscillator (voltage-controlling oscillator, VCO) by the microwave nonlinear autonomous circuit harmonic balance method in millimeter-wave bands are studied in the paper. Firstly, the quasi-periodic characteristic of the steady-state response of the VCO modulated by a periodic signal is proved. Then, on the bases of the harmonic balance analysis and the inter-modulation balance analysis, a novel method for obtaining the steady-state tuning performance and the nonlinear frequency-modulation distortion characteristic of the VCO is presented. The total analysis process is aimed to a kind of NRD-guide Gunn diode VCO. The large-signal lumped equivalent circuit model of the millimeter-wave P⁺N-junction varactor is also given for explaining the algorithm and the principle of the NRD-guide VCO.     

板条侧面绝热技术研究

 分析了当侧面绝热不彻底时所带来的侧向温度梯度对板条光程畸变造成的影响，提出采用吸收材料吸收板条的自发辐射，控制吸收材料的温升使之与板条中心的平均温度相同的方法来实现板条侧面绝热，并给出了“隔热层+吸收层+铜热沉”的绝热结构的设计方法。板条热透镜效应实验结果表明，在500Hz重复频率下，未装绝热结构的板条热焦距为0.78m，而装有绝热结构的板条的热焦距为1.93m，热聚焦大为改善。