用于显示的透射型法布里-珀罗光调制器

提出了一种用于显示的,基于透射型法布里-珀罗干涉的微机电系统(MEMS)光学调制器。基于多光束干涉原理分析了调制器的光学特性,推导出了调制器结构的特征参量。分析表明,当调制器的腔长为cλ/4时,透射光可以实现暗态显示;当调制器的腔长取为零或cλ/2时,透射光可以实现亮态显示。通过控制法布里-珀罗腔长,就可实现调制器的明暗调制。理论上证明了该调制器用于显示的可行性。设计了一种基于微机电系统的透射型法布里-珀罗光学调制器结构,该调制器的理论衬比度达到150。仿真结果表明,该调制器具有2.4 V的低电压静电驱动性能。     

基于单片机的数字化调光装置的设计与实现

介绍了一种光学仪器照明调光电路的创新设计。通过由Atmega8单片机微控制器产生的PWM信号来控制卤钨灯的亮度。照明调光电路具有电路简单,光强输出稳定,其亮度可数字化线性调节和具有记忆功能等特点,同时还可以通过计算机实现自动调光。     

High-j proton alignments in 101Pd

High-spin states in ¹⁰¹Pd have been investigated by means of in-beam γ-ray spectroscopic techniques via the ⁷⁶Ge(²⁸Si, 3n) reaction at beam energies of 85 and 95 MeV. The previously known d _5/2 and 1/2^?[550] bands were extended to higher spins, and the unfavored signature branch of the 1/2^?[550] band was built. The band crossings observed experimentally are explained by the alignment of g _9/2 protons. The band properties in ¹⁰¹Pd are compared with those in the neighboring nuclei and are discussed within the framework of the cranked shell model (CSM).     

Diagnostic value of nonlinear optical signals from collagen matrix in the detection of epithelial precancer

During precancer development in epithelium, neoplastic cells remodel the underlying stroma, for example, the basement membrane, capillaries, fibroblasts, and extracellular matrix. The purpose of this study is to investigate the relationship between the nonlinear optical signals from the collagen matrix in stroma and the progression of early epithelial carcinogenesis. Two-photon excited fluorescence (TPEF) and second harmonic generation (SHG) signals were measured from the stroma of hamster oral cheek pouch in vivo. We found that three features, including the intensity ratio of TPEF over SHG, the spatial frequency distribution, and the texture feature of SHG images, provide the quantitative identification of epithelial precancer at different pathologic stages. We demonstrated that the combination of all three features by using a support vector machine algorithm can significantly improve the accuracy in the detection of epithelial precancer.     

Tunable chirped microwave photonic filter employing a dispersive Mach-Zehnder structure

A Mach-Zehnder structure with modulation in one arm and dispersive time delay in the other is proposed to implement highly flexible single-bandpass chirped microwave photonic filters based on broadband optical sources. Both the amplitude response and the time delay slope can be fully reconfigured via control of the optical spectra and dispersion. The passband can also be widely tuned without changing the shape. A chirped filter with a bandwidth of ～4?GHz, a delay slope of ～-0.6?ns/GHz, and a tunability up to 40?GHz is demonstrated experimentally.     

The fluctuation property of blown sand particles and the wind-sand flow evolution studied by numerical method

Sand particles blown by wind cause serious environmental problems and many researchers are trying to understand the dynamic properties of blown sand better. But the existing numerical approaches have not been able to simulate many important characteristics of wind-sand flow. In this paper, the evolution and fluctuation properties of blown sand at a dynamic steady state are investigated by using a more effective method. Using the LES (large eddy simulation) method for air phase movement and the DEM (discrete element method) for solid phase movement along with the existing particle-bed splashing function, we have characterized the whole movement property of the wind-sand system. The results indicate that the saturation time decreases with the inlet friction velocity, and it gradually reaches the shortest saturation time of about 1s; the saturation length, which is about 14 m at the usual wind velocity, first increases with wind velocity and then reaches a plateau; within the saturation length, the sand transport rate at different positions varies with time; the sand transport rate of the stable wind-sand flow is non-uniform with distance downwind and time, and has a notable correlation with the inflow friction velocity.     

Measurement of wurtzite ZnO/rutile TiO2 heterojunction band offsets by x-ray photoelectron spectroscopy

Four novel dmit complexes: [(C₂H₅)₄N][Ni (dmit)₂], [(C₃H₇)₄N][Ni(dmit)₂], [(C₂H₅)₄N][Au(dmit)₂] and [(C₃H₇)₄N][Au(dmit)₂], abbreviated as EtNi, PrNi, EtAu, and PrAu, were synthesized. The third-order nonlinear optical properties of them in acetonitrile solutions were investigated by using the Z-scan technique with 20 ps pulses width at 1064 nm. When the on-axis irradiance at focus I ₀ was 5.025 GW/cm², the nonlinear refraction coefficient n ₂, the third-order nonlinear susceptibility χ ⁽³⁾, the molecular second-order hyperpolarizability γ of the four types of material were obtained with subject to Z-scan curves, and these indexes were with the magnitudes of 10⁻¹⁸ m²/W, 10⁻¹³ esu, and 10⁻³¹ esu, respectively. The nonlinear absorption coefficient β of Ni samples had the 10⁻¹² m/W scale. The impact of different metals and cations on the third-order nonlinear optical properties of materials was analyzed. Through the derivation, the result suggests that these dmit complexes are promising candidates for applications to nonlinear optical devices manufacture in the near-infrared waveband.