模式偏置波前传感器理论模拟及实验验证

将模式偏置法与全息多重存储法波前传感器原理联系起来,通过研究模式偏置波前传感器的输出响应特性,间接得到全息模式波前传感器的运行规律.对模式偏置波前传感器进行理论分析与总结,并建立简化模型,针对若干阶Zernike像差,通过数值模拟对理论结果进行验证.模拟结果显示:传感器输出信号与各种类型待测像差系数有不同的变化关系,这...     

Neural network applied to reconstruction of complex objects based on fringe projection

The neural network has been introduced into the reconstruction of the complex object based on fringe projection. In this method, the neural network with powerful property of approximation is used to get the continuous approximate function of a discrete fringe pattern captured by an image frame grabber. The depth-related phase of the measured object modulated into the fringe pattern can be demodulated by dealing with the approximate function. Compared with the Fourier transform profilometry (FTP), in the network method, one deformed fringe pattern is needed to reconstruct the tested object, and a high spatial resolution is maintained for no filtering process. Therefore, this method performs better than FTP in the measurement of the complex object. Moreover, the network method is capable of demodulating more depth-related phase even in the case that the local shadow exists in the fringe pattern. Computer simulations and experiments validate the feasibility of this method.     

Modal attenuation in metal-clad graded-index slab optical waveguides

The paper presents the influence of refractive profile shape on the distribution of modal attenuation in planar metal-clad optical waveguide structures. A calculation method has been presented in which we applied the Snyder–Love expression on modal attenuation coefficients and matrix method 4 × 4 for the analysis of planar waveguides. The obtained results are almost identical with the exact results for refractive profiles: the parabolic, exponential, Gaussian and linear ones. It has been demonstrated that the applied calculation method can be used in waveguides of any profiles of the refractive index.     

Ag implantation-induced modification of Ni–Ti shape memory alloy thin films

Nanocrystalline thin films of Ni–Ti shape memory alloy are deposited on an Si substrate by the DC-magnetron co-sputtering technique and 120?keV Ag ions are implanted at different fluences. The thickness and composition of the pristine films are determined by Rutherford Backscattering Spectrometry (RBS). X-Ray diffraction (XRD), atomic force microscopy (AFM) and four-point probe resistivity methods have been used to study the structural, morphological and electrical transport properties. XRD analysis has revealed the existence of martensitic and austenite phases in the pristine film and also evidenced the structural changes in Ag-implanted Ni–Ti films at different fluences. AFM studies have revealed that surface roughness and grain size of Ni–Ti films have decreased with an increase in ion fluence. The modifications in the mechanical behaviour of implanted Ni–Ti films w.r.t pristine film is determined by using a Nano-indentation tester at room temperature. Higher hardness and the ratio of higher hardness (H) to elastic modulus (E_r) are observed for the film implanted at an optimized fluence of 9?×?10¹⁵ ions/cm². This improvement in mechanical behaviour could be understood in terms of grain refinement and dislocation induced by the Ag ion implantation in the Ni–Ti thin films.     

A novel fringe adaptation method for digital projector

Aimed to obtain high-quality sinusoidal fringe projection, a new method to correct the output fringe of digital projector is presented. The method is based on the proposed fringe transform model, which describes the relationship of the input and output fringe pattern. Firstly, a series of fringe patterns are projected and from the fringe images, the transform function is calculated by the pattern shifting method. At last, by modifying the input fringe pattern, a standard sinusoidal output fringe can be achieved. Different from the previous methods, the waveform nonlinearity is estimated by varying the intensity of the projected fringe pixel by pixel; thus the waveform nonlinearity can be estimated precisely and the time cost is considerably reduced. Experimental results show that by modification of the input projection patterns the projector can project fringe with high-quality sinusoidal waveform leading to high performance of the projection system.     

温度对CdS纳米颗粒形状和光致发光特性的影响

采用反胶束法,在常温和低温下(接近零度)合成了硅土包裹的CdS纳米颗粒.高分辨电镜表明常温下合成的颗粒呈现直径小于5 nm的球形,而在低温下出现了短棒形和长达微米量级的线形.通过对实验过程的分析表明:不仅合成CdS纳米颗粒溶液的浓度,而且温度对CdS纳米颗粒的形状产生了重要的影响.进一步研究了CdS纳米颗粒的光致发光特性.     

数字散斑时间序列相关三维面形测量方法

提出了一种测量三维面形的新方法,将随机数字散斑投影到参考平面上,深度方向等间距平移参考平面,用CCD提取时间序列散斑参考集R（t)。然后用被测物体取代参考平面,获取物体调制散斑图像O。O中的任意子图像O（x,y)与参考平面簇中对应位置的时间序列子图像R（x,y:t)之间的交叉相关值曲线呈高斯分布,其峰值位置就是被测物点的高度。该方法摆脱了以前数字散斑测量法水平相关思路,是真正的时间序列相关方法,且原理简单,测量精度高,不需要复杂的相位展开和校准过程,特别适用于测量突变面形和空间离散面形,根据测量结果的误差特征,提出了相关值加权邻平均插值算法,能得到比邻平均算法更好的测量结果。     

用于半导体激光器的等共轭距双曲柱面镜系统

论述用于把窗口尺寸为０－１２８５ｍ ｍ ×３ ．２３９０ ｍ ｍ 的半导体激光器发出４４°×１３°的发散光束压缩成在±０－００２５ｒａｄ 内出射光的柱面镜系统。该系统的核心是用两组互相垂直、且共轭距相等的双曲柱面镜,把激光器的条形窗口的像变粗变短;然后,再用透镜组把此像“准直”到“无限远”     

用超对称性和形不变性方法求解环形振子的能谱和波函数

运用超对称性和形不变性方法计算环形振子的能量本征值和本征波函数.所得到的能谱公式与用费曼路径积分方法得到的严格解完全一致.