A novel strongly correlated electronic thin-film laser energy/power meter based on anisotropic Seebeck effect

Strongly correlated electronic (SCE) materials including high-temperature superconducting cuprate and colossal magnetoresistance manganite thin films demonstrate tremendous anisotropic Seebeck effect which makes them very promising for developing high-performance laser detectors. In this work, laser-induced thermoelectric voltage (LITV) signals with nanosecond response time have been measured in SCE La_1?x Pb _x MnO₃ thin films based on anisotropic Seebeck effect at room temperature. The magnitude of the LITV signals increases linearly with laser energy/power density in a wide range of laser wavelengths from ultraviolet, visible to infrared based on which a novel SCE thin-film laser energy/power meter has been developed.     

Improving the performance of thermoelectric devices by doping Ag in LaPbMnO3 thin films

A series of Ag-doped La_0.6Pb_0.4MnO₃ thin films were grown on vicinal cut substrates by pulsed laser deposition (PLD). Laser-induced thermoelectric voltages (LITV) had been observed in these films, and these LITV signals had been demonstrated to originate from the anisotropic Seebeck effect. By doping Ag to an optimum value, it was found that the peak values (U_P) of the LITV signals were maximized, and the full-width at half-maximum (τ) of the response curves of LITV were minimized at the same time. The figure of merit (F_m) of the device used as photodetector is greatly improved by doping Ag in La_0.6Pb_0.4MnO₃ thin films. The possible reason for these improvements had been well discussed.     

拍摄脉冲全息肖象母版的研究

本文介绍了我们在拍摄脉冲全息肖象母版方面的研究工作.讨论了拍摄工作中所需要特别注意的若干问题.如:人眼安全、对易律失效、消除双频条纹、如何获得高亮度图象等问题.此外,还介绍了我们拍摄脉冲全息母版时,在未使用Q开关的情况下,同样获得了高质量全息肖象母版的经验.     

LaCaMnO3 thin film laser energy/power meter

A prototype laser energy/power meter was designed based on the anisotropic Seebeck effect of LaCaMnO₃ thin film grown on vicinal cut LaAlO₃ substrate. The optical response of this device to the pulsed laser and the chopped CW laser was measured from infrared to ultraviolet. The peak voltage of the measured signal shows a good linear relation to the laser energy and power in the measured range. It was shown that at 1064 nm wavelength, this prototype device demonstrates higher sensitivity than that of commercial device.     

利用压电移相器判别物体变形方向

本文提出了一种在实时全息干涉计量术中利用压电移相器判别物体形变方向的简单而可靠的方法,文中给出了它的原理和实验验证.     

光纤双向应变-位移点式传感器

选择不同间距的基片自由端和不同长度的自由悬垂光纤研制了利用光纤弯曲损耗的光纤双向应变-位移传感器.该传感器可分别用于测量应变和位移.实验表明:悬臂梁上的应变标准误差约为～26 με.微位移架上的位移标准误差约～0.06 mm.基本满足建筑结构对测量精度的要求.     

Forecasting business cycle with chaotic time series based on neural network with weighted fuzzy membership functions

This study presents a forecasting model of cyclical fluctuations of the economy based on the time delay coordinate embedding method. The model uses a neuro-fuzzy network called neural network with weighted fuzzy membership functions (NEWFM). The preprocessed time series of the leading composite index using the time delay coordinate embedding method are used as input data to the NEWFM to forecast the business cycle. A comparative study is conducted using other methods based on wavelet transform and Principal Component Analysis for the performance comparison. The forecasting results are tested using a linear regression analysis to compare the approximation of the input data against the target class, gross domestic product (GDP). The chaos based model captures nonlinear dynamics and interactions within the system, which other two models ignore. The test results demonstrated that chaos based method significantly improved the prediction capability, thereby demonstrating superior performance to the other methods.     

准直透镜反射光引起的一个问题

准直透镜主要用于产生平行光束然而,由于其表面的反射作用,在准直后的平行光束中,还存在一束会聚光束这会聚光束与平行光束相比虽很微弱,但在其会聚点附近具有较高的强度,在安排光路时应注意避开它,否则会带来某种程度的干扰本文讨论了这种反射光对全息记录带来的影响和应注意的问题,并根据衍射理论导出了反射光的会聚位置,结果与实验符合甚好.