Waveguide-based near-eye display with dual-channel exit pupil expander

We propose a waveguide-based near-eye display featuring a dual-channel exit pupil expander, which is composed of an in-coupler, relay gratings, and an out-coupler. Unlike the conventional waveguide-based near-eye displays, whose field of views are usually non-split or partially split, our dual-channel exit pupil expander is able to evenly split the field of view into two halves. The greatest benefit of doing so is that the upper limit of field of view could be significantly increased. The design rules for all components, including the microdisplay, collimating lens, waveguide and gratings, have been studied. The refractive index and dimension of waveguide are identified as two factors that limit the field of view. In what follows, its key specifications are recapitulated. Field of view is 70° (diagonal), eye relief is 15 mm, exit pupil is 20 × 9 mm², modulation transfer function is above 0.591 at 30 cycle/degree, contrast ratio is 13, and distortion is 1.38%.     

Preparation of periodic surface structures on doped poly(methyl metacrylate) films by irradiation with KrF excimer laser

In this work, we describe laser modification of poly(methyl methacrylate) films doped with Fast Red ITR, followed by dopant exclusion from the bulk polymer. By this procedure, the polymer can be modified under extremely mild conditions. Creation of surface ordered structure was observed already after application of 15 pulses and 12 mJ cm⁻² fluence. Formation of grating begins in the hottest places and tends to form concentric semi-circles around them. The mechanism of surface ordered structure formation is attributed to polymer ablation, which is more pronounced in the place of higher light intensity. The smoothness of the underlying substrate plays a key role in the quality of surface ordered structure. Most regular grating structures were obtained on polymer films deposited on atomically ‘flat’ Si substrates. After laser patterning, the dopant was removed from the polymer by soaking the film in methanol.     

基于单元平均应变的结构多损伤静态识别

利用长标距布喇格光纤光栅（FBG）传感器，可以测量结构一定长度的平均应变。在介绍单元平均应变的基础上，采用单元平均抗弯刚度和广义单元平均中性轴高度作为识别参数，通过工字形悬臂钢梁和简支钢梁的多损伤数值模拟进行了验证，说明基于单元平均应变的结构静态损伤识别方法是可行的。     

光栅尺的防护设计与研究

光栅在应用中容易出现被切削液污染、被铁屑划伤的现象,从而使测量精度受到影响,甚至导致光栅无法工作。通过分析光栅的结构原理以及工作原理,结合数控机床的工作要求,设计出光栅防护装置,使光栅尺在封闭防护的条件下正常工作,保证了数控机床闭环控制的高精度、精确性。     

基于Cortex-M4的环面蜗杆检测仪的全闭环控制系统

针对环面蜗杆检测仪系统控制及定位精度的需要,采用Cortex M4作为主控制器,控制步进电机驱动载物台运动,步进电机采用闭环控制。光栅尺实时检测XYZ导轨的位置信息,并把光栅信号作为反馈信号,构成闭环运动控制系统,实现坐标系中XYZ轴的运动和时栅转台旋转的高精度定位。步进电机的驱动采用软硬件细分方法,克服了步进电机爬行和丢步现象。实验表明：该系统采用全闭环控制、步进电机软硬件细分方法,实现了三坐标轴±2 μm 的精密定位,保证了环面蜗杆检测仪的准确测量。     

修井作业中油管长度的检测

环形防喷器是在带压作业中实现高温高压的关键部件。油管上提或下降时,需对管箍位置进行检测。针对油田修井作业所需,设计了一种光栅检测的连续油管长度在线测量系统。系统采用光栅作为油管长度测量的传感器,用51单片机构成测量控制系统核心,根据实际需要设计了硬件电路并编写了软件程序,准确测量下井油管的单根长度和总体长度,此技术可延长环形防喷器寿命,节约成本,为修井作业时管箍及油管位置的判断及井口数据提供依据。     

基于光纤光栅的GIS导体温度巡检方法与装置

针对GIS设备导体温度监测和回路过热性故障预防,在分析光纤光栅测温原理和成像解调技术的基础上,提出了一种基于光纤光栅温度传感网络的GIS导体温度巡检方案。通过现场温升试验建立了GIS导体温度测量模型并根据相关标准制定了GIS导体温度过热性故障判据。研制了可应用于不同GIS母线温度测量的便携式巡检装置,设计了温度巡检装置的硬件系统和软件系统。现场实验表明该设备工作稳定,测温精度高,对于保障GIS设备的安全稳定运行具有现实意义。     

Application of ionic liquids in photopolymerizable holographic materials

The influence of ionic liquids in photopolymerizable holographic materials was investigated extensively. The structures of ionic liquids have important effect on the properties of the materials. Although not all tested ionic liquids can improve the properties of the materials, the ionic liquids based on imidazolium, pyridium, or phosphonium with appropriate counter anions can be used as additives to increase the sensitivity, the diffraction efficiency, and the resolution of the materials in the thin hologram. Polymerizable ionic liquids have also been used as additives. Higher sensitivity, higher diffraction efficiency and higher resolution were obtained as well. These ionic liquids can carry out the photopolymerization during exposure to UV light to recording the hologram. They may assist to form a more stable hologram.     

基于ARM的直线式时栅传感器自动闭环控制系统设计

设计的自动闭环控制系统,是为了完成直线式时栅传感器数据的快速采样,提高测试效率。基于PHILIPS公司的ARM处理器LPC2214作为主控芯片,设计了控制电路,控制步进电动机驱动滚珠丝杠,带动直线式时栅传感器的动测头与直线光栅的扫描头同步运动,同时接收直线式时栅传感器的反馈信号,并与上位机之间进行串口通信。实践证明:系统响应速度快,控制精度能达到0.1μm。     

一款光栅尺数显表的设计

叙述一款光栅尺数显表的设计,介绍对光栅尺传感器输出脉冲的细分辨向原理。基于该原理,可将光栅尺测量分辨率提高4倍。同时简要介绍了单片机对光栅尺传感器输出数据的处理。该数显表采用计数器芯片计数与单片机对数据处理相结合的技术。具有体积小、成本低、计量准确、结构简单、工作可靠、校准简单等特点。