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%.     

光源光色对隧道照明效果的影响

为了研究隧道照明中光源的光色,在3种照明水平和负对比条件下,比较了5种色温的LED光源与传统照明光源高压钠灯(HPS)、金卤灯(MH)对隧道照明效果的影响。通过反应时间实验方法,分析了光源光色分别与反应时间和人眼瞳孔大小之间的变化关系。实验结果显示,在高照明水平下,高色温LED光源的视觉功效最高,光生物效应最显著;而在中间视觉照明水平下,中间色温的LED光源的视觉功效和光生物效应最显著。合理选择适用隧道照明各区段的光源应考虑光源光色对视觉功效和光生物效应的综合影响,并值得进一步研究。     

红外头盔式眼动仪的瞳孔中心定位算法

为了提高瞳孔中心定位精度,降低运算复杂度,首先采用星射线方法获取瞳孔边界点,与对整幅图搜索相比,计算量大大减小.设定感兴趣区域,对眼皮、眼睫毛及光斑干扰产生的虚假特征点进行剔除,然后利用特征点通过随机化的椭圆拟合定位瞳孔中心.随机化椭圆拟合允许杂质点的存在,确保了拟合定位算法的准确性,对虚假点的剔除更进一步加快了拟合速度.在连续帧处理时通过瞳孔像素数的变化快速对眨眼进行检测,区分眨眼与伪眨眼.实验结果表明,该算法简单且鲁棒性好.     

一种基于圆形角点的瞳孔定位算法*

提出了一种利用圆形角点定位瞳孔的算法。该算法主要在定位到人眼区域的基础上,利用改进的SUSAN算法寻找圆形角点;然后根据梯度放缩计算角点向量的梯度值,最后通过筛选函数输出瞳孔中心位置及亮瞳面积,准确地定位到瞳孔,并根据亮瞳的大小定位到瞳孔区域中心。实验结果表明本算法是准确可靠的。     

Pupil center detection with a single webcam for gaze tracking

This paper presents a user friendly approach to localize the pupil center with a single web camera.Several methods have been proposed to determine the coordinates of the pupil center in an image,but with practical limitations.The proposed method can track the user’s eye movements in real time under normal image resolution and lighting conditions using a regular webcam,without special equipment such as infrared illuminators.After the pre-processing steps used to deal with illumination variations,the pupil center is detected using iterative thresholding by applying geometric constraints.Experimental results show that robustness and speed in determining the pupil’s location in real time for users of various ethnicities,under various lighting conditions,at different distances from the webcam and with standard resolution images.     

Exit pupil expander with a large field of view based on diffractive optics

Abstract— The field of view is an important parameter of a near‐to‐eye display. To achieve an immersive viewing experience, the field of view should be as high as possible. Presently, in most of the commercially available devices the field of view is between 15° and 30°. In this paper, a large‐field‐of‐view exit pupil expander that is based on diffractive optics was demonstrated. Usually these types of diffractive expanders cannot have a field of view much more than 25°. Here, an exit pupil expander with an extended field of view, based on two stacked plates, was demonstrated. The expander is designed for green light and it achieves a field of view of more than 40°.     

光学系统轴向超分辨滤波器的研究

运用最优化算法，存给定超分辨模型和爱里模型主瓣最大亮度比的斯特列耳比S的条件下，设计出3区振幅型轴向超分辨光瞳滤波器。给出设计模型和实例。结果表明，该超分辨滤波器优越于文献。     

用傅里叶变换计算单缝衍射的光强分布

现代光学和通讯理论由于引入了傅里叶变换的方法，使计算光学系统和通讯系统的物像的对应关系简洁、清晰。该文用傅氏变换计算长为２ａ、照度为Ａ的均匀缝光源在观察面上的光强分布为Ｉ（ｘ）＝│Ｅ（ｘ）│＾２＝ＡＡ＾２ａ＾２（ｓｉｎ２πｆａ／２πｆａ）此方法也可运用于矩形孔、圆孔等。     

基于人眼检测优化的立体人机交互技术的研究

随着3D显示技术的逐渐成熟,越来越多基于3D显示技术的产品被应用于各个领域,例如3D电影、裸眼3D电视、体感交互式系统和影像教学等。基于3D显示的人机交互系统也是近年来越来越热门的研究方向,但是却没有高效地利用深度信息作为交互的线索,因此本文提出将3D显示与体感交互结合,实现立体人机交互的虚拟键盘,让用户只需点击屏幕前方键盘的图像即可进行对应按键信息的录入和编辑,其帧率可达10.6fps。针对3D显示中用户视角偏离会导致按键的像在视觉上的偏移,容易造成误输入的问题,在系统中整合人眼检测功能,修正因视角偏离带来按键定位误差,从而实现了准确率100%的字符输入交互功能。     

Teacher attitudes and temperament as a measure of teacher-pupil rapport.

To attempt to determine the personality and temperament factors measured by the Minnesota Teacher Attitude Inventory, scores on the MTAI were correlated with scores on the scales of the Guilford-Zimmerman Temperament Survey, for a sample of 300 public school teachers. Teachers who have high rapport with pupils are characterized by personal cooperativeness, friendliness, objectivity, and emotional stability." (PsycINFO Database Record (c) 2010 APA, all rights reserved)