抑制穿过具有倾斜角度的介质探测成像时产生的寄生干涉条纹现象

进行穿透扫描探测实验时,在回波图像中发现了由于介质具有倾斜角度产生的周期性干涉条纹,这种干涉条纹对介质后或者介质中的目标成像有严重影响.研究表明,这种干涉条纹主要由介质表面反射波及透射后的层面反射波引起.文中建立点源辐射模型分析干涉条纹现象的形成机理,推导出薄层介质的干涉条纹间距表达式.考虑到天线的影响,建立了角锥喇叭天线近场模型,并且基于该模型进行精确的电磁仿真.商用软件Computer SimulationTechnology的电磁仿真结果与MATLAB程序的数字计算结果进一步验证了干涉条纹的成因分析及其与介质倾斜角度的关系.从推导的薄层介质干涉条纹间距表达式可以看出,干涉条纹间距与介质倾斜角度有关,控制影响条纹间距的因素,可以抑制干涉条纹现象,从而达到提高目标分辨率和成像质量的效果.     

Controlling the Microstructure of Conjugated Polymers in High-Mobility Monolayer Transistors via the Dissolution Temperature

It remains a challenge to precisely tailor the morphology of polymer monolayers to control charge transport. Herein, the effect of the dissolution temperature (T_dis) is investigated as a powerful strategy for morphology control. Low T_dis values cause extended polymer aggregation in solution and induce larger nanofibrils in a monolayer network with more pronounced π–π stacking. The field-effect mobility of the corresponding monolayer transistors is significantly enhanced by a factor of four compared to devices obtained from high T_dis with a value approaching 1 cm² V⁻¹ s⁻¹. Besides that, the solution kinetics reveal a higher growth rate of aggregates at low T_dis, and filtration experiments further confirm that the dependence of the fibril width in monolayers on T_dis is consistent with the aggregate size in solution. The generalizability of the T_dis effect on polymer aggregation is demonstrated using three other conjugated polymer systems. These results open new avenues for the precise control of polymer aggregation for high-mobility monolayer transistors.     

Mapping of vibration amplitudes by time average holography in Bi12SiO20 crystals

We report the performance of a holographic set-up with a Bi₁₂SiO₂₀ (BSO) photorefractive crystal for measuring vibration amplitudes in a time average holography system. The volume hologram is recorded with the 514.5 nm wavelength of an Ar⁺ laser. In this set-up the reference beam is sinusoidally phase-modulated with the same frequency of the vibrating object. By increasing the value of the phase modulation, the fringes of the time average pattern run along the object surface, so that the vibration amplitude mapping is carried out. This technique allows the improvement of the measurement sensitivity compared with conventional time average holography, even for interferograms with poor visibility.     

莫尔(干涉)条纹计数细分和辨向技术的研究

提出了一种双阈值计数法与正切细分法结合使用的莫尔(干涉)条纹计数细分和辨向技术。通过阈值的设置,实现了整周期信号的辨向和计数,消除了直流电平漂移和高频噪声引起的计数误差;采用正切细分法,对不足一个信号周期的条纹位移,实现了正确的辨向和高倍数细分。该方法同时具有双阈值计数法和正切细分法的优点,具有强的环境适应性和抗干扰能力。     

用激光干涉法测量长度的智能化处理技术研究

介绍利用激光干涉与数字图像处理技术以及应用FFT分析干涉涤纹方法，分析并解决测量端面长度标准中条纹图的处理技术。应用这种方法不但提高了测试过程的自动化程度，而且大大地提高了测量精度。文中给出了最典型的端面长度标准量块的干涉条纹小数部分的实测结果。     

用干涉条纹重迭法测量晶体双折射率差

本介绍用干涉条纹的重叠法测量晶体双折射的过程。此方法是在D．F．Heller先生的基础上，用干涉条纹取代光机的Tallbot像，主要优点是条纹的对比度好。     

基于等厚干涉的轴向空间相干度分析及其在表面形状测量中的可行性探讨

从等厚子干涉的解释出发，推导出了二维空间的相干方程。基于空间相干方程，利用SLM产生了一个新的空间非相干光源。同时提出了新的相移方案，并结合这个新的相移方案，实现了轴向空间距离的探测和干涉条纹的相移。分析了空间方向角度相干方程的影响，并给出了实验验证。通过对非相干光源的参数和特定的空间距离以及空间方向角的匹配，重建了一个具有标准段差的实际物体的表现形状。为光学表面形状测量提供了新的思路。     

一种正三角形结构的双光束干涉装置

依据波动光学的原理,介绍了一种能产生双光束干涉现象的正三角形干涉装置,解析推导并分析了该干涉结构发生等倾干涉的条件及干涉斑纹的分布规律;同时讨论了这一光学干涉结构的可能应用,及其对光学干涉的教学研究的补充与辅助作用.