3-D Liquid Crystal Displays and Their Applications

Three-dimensional (3-D) data is regularly used to create 3-D images that are rendered onto a plane and shown on a two-dimensional (2-D) display. Stereoscopic displays are becoming more widespread and are currently available at consumer level prices. With these displays it is possible to see images with a high-quality perception of depth and with a greater sense of realism. It is an exciting time in the 3-D displays market as the current generation of 3-D display technologies continues to develop. A number of technologies for 3-D displays have existed for some time, many of which are based on liquid crystal displays (LCDs). LCDs combined with the parallax barrier method have a number of advantages in terms of cost, ease of manufacture, size, weight,and most importantly the ability to switch from 2-D to 3-D mode. Several consumer products are available based on this type of display. Applications such as entertainment, scientific visualization, advertising, and education benefit greatly from the improved realism offered by stereoscopic displays. There are many challenges to creating suitable images for 3-D displays; some have been solved and others are receiving attention. In order to build the 3-D display market, industry will need to tackle all of them in order to support the content creators and provide the features and ease of use that end users require. The aim of this paper is to describe and compare the core 3-D display technologies, bring together a number of important considerations for content creation and discuss some of the applications that have a strong benefit from using 3-D images on a 3-D display.     

Polymer-MEMS-Based Optoelectronic Display

In this paper, a novel all-polymer integrated microsystem, which realizes a 2-D display by integrating a 1-D array of polymer light-emitting diodes (PLEDs) with a polymer scanner of microelectromechanical system (MEMS), is presented. Electronic modulation of PLEDs forms the first dimension of the display (fast scan), and the scanner actuation orthogonal to the direction of PLED lineup forms the second one (slow scan). MEMS scanner (actuator) is fabricated on a polymer composite (FR4 material) with a double-sided process using lithography to pattern copper lines and laser micromachining to cut the scanner outline. PLEDs are fabricated on polyethylene terephthalate sheets. They have a thin-film structure of indium tin oxide, poly (3,4-ethylenedioxythiophene) poly (styrenesulfonate), poly [2-methoxy-5-(2'-ethyl-hexyloxy)-1,4-phenylene vinylene], and aluminum. The scanner is actuated electromagnetically in its slow-scan resonance mode at 49 Hz, generating a maximum displacement of 3.5 mm at a drive power of 84 mW with the help of a mini permanent magnet attached to the tip of the scanner and an off-chip energizing coil. Turn-on voltage of a PLED is 7.5 V, and each one generate a luminance of 0.3 cd/m² at 13 V, consuming 1.1-mA current. Successful operation of the integrated-display system is shown by forming a checker box image with a resolution of 20 × 7 and a size of 9 mm by 3.4 mm.     

液晶光学相控阵的双波束成形和2维扫描技术

为了在光学相控阵中实现双波束成形和2维扫描,以玻璃作为基底材料,以液晶作为移相介质,利用液晶的电控移相特性,对入射光束进行双波束成形和相控空间扫描;采用现场可编程门阵列芯片对液晶驱动芯片进行波控数据发送,完成对液晶移相阵列的电压驱动,从而达到电控光束扫描功能,完成单个透射型液晶光学相控阵组件的研制;利用该组件的电控光束扫描功能,采用多个组件级联的方式,实现基于透射型液晶光学相控阵组件的双波束成形和2维扫描技术。结果表明,该系统能够实现双波束独立偏转控制,以及高精度的空间2维偏转。     

Tomorrow's TV - the grating light valve

The host of technologies tussling to displace the CRT have yet to face one strong contender: the grating light valve (GLV). This paper describes the construction and operation of GLVs which are MEMS technology electrostatically operated ribbon-shaped mirrors. Their main application, also outlined in this paper, is in large sized, high quality laser projection displays.     

Array interconnection for rearrangeable 2-D MEMS optical switch

Two-dimensional (2-D) microelectromechanical systems (MEMS) optical switches can be constructed by arranging the MEMS-actuated micromirrors as an array. We consider here the switching capability, routing, and optimization of the rectangular array interconnection on which the capability and efficiency of 2-D MEMS switches depend. The switching capability of a rectangular array is proved analytically. Two routing algorithms, namely, the most-bend routing and the least-bend routing, are developed, which, respectively, maximize and minimize the number of 2 /spl times/ 2 switches in the "bend" state. A method of counting the number of permutations realizable with a given number of switches in the "bend" state is proposed to evaluate the performance of both routing schemes. The understanding of the underlying interconnection pattern enables us to study the problem of constructing rearrangeable optical switches of arbitrary size.     

A Dynamic 3-D Surface Profilometer With Nanoscale Measurement Resolution and MHz Bandwidth for MEMS Characterization

Commercialization of microelectromechanical systems (MEMS) has made accurate dynamic characterization a major challenge in design and fabrication. In view of this need, a dynamic 3-D surface profilometer involving white light interferometric scanning principle with a stroboscopic LED light source was developed. The developed instrument was applied to a microcantilever beam used in atomic force microscopy (AFM) to analyze its full-field resonant vibratory behavior. The first five resonant vibration modes were fully characterized with vertical measurement accuracy of 3-5 nm and vertical measurement in the range of tens of micrometers. The experimental results were consistent with the outcomes of the theoretical simulation by ANSYS. Using stroboscopic illumination and white light vertical scanning techniques, the developed static and dynamic 3D nanoscale surface profilometry of MEMS devices can achieve measurement range of tens of micrometers and dynamic bandwidth of up to 1-MHz resonance frequency.     

Two-dimensional LED arrays for virtual display image sources

The design and fabrication of large-scale two-dimensional (2-D) arrays of visible light emitting diodes (LED's) is described along with their implementation as image sources for prototype virtual displays. The LED pixels were fabricated in the InGaAlP material system using a double mesa etch process. Pixel characteristics are presented and used to predict display luminance properties. The 10-μm square LED's produced external quantum efficiencies of 0.5% with an emission spectrum peaked near 650 nm (red). This performance level allowed the target display luminance of 10 fL to be attained with just 2.9 mW of array power consumption. The LED arrays consisted of 240 columns×144 rows (~VGA/8) with pixels on a 20-μm pitch and were driven in a column major matrix addressing mode at 60 frames per second for image display. Pixels were driven at a constant current with pulse width modulation to achieve sixteen levels of gray. An analysis of array luminance uniformity is presented. Sample images of text, graphics, and gray scale images demonstrate the capabilities of the LED arrays as monochrome image sources for virtual displays     

电力系统中MEMS光开关切换路径优化控制的方法

针对电力系统中微机电系统(MEMS)光开关在切换备纤时可能受到光控信号的影响而造成光时域反射仪(OTDR)发生损坏的问题,文章提出了一种电力系统中MEMS光开关切换路径优化控制的方法,在对MEMS光开关进行完整的扫描后得到其精确的光信号通道功率等高图,然后再对其切换路径进行优化控制,使得MEMS光开关可以在平衡控制通道...     

白光干涉检测仪垂直扫描系统设计

白光垂直扫描干涉测量方法具有高精度、大量程并且为非接触测量等优点,因此被广泛地应用于半导体、微机电系统(MEMS)等检测领域.传统的白光扫描干涉仪采用压电(PZT)陶瓷驱动器,虽然能实现高精度的测量,但存在量程小、测量效率低等缺点.基于此,提出了以步进电机作为驱动器、高精度光栅尺作为位置反馈的白光干涉垂直扫描运动平台,并设计了以现场可编程逻辑门阵列(FPGA)为核心处理器的控制板卡.实验证明,该运动平台在运动速度为50 μm/s时,定位偏差小于15 nm,最大行程为3 mm,实现了高精度、大行程以及高效率的扫描检测.可以以较低的成本实现对具有高深宽比的微纳器件形貌的检测.     

Scanning Polymeric Waveguide Design of a 2-D Display System

Many small-scale display systems used in head-mounted displays (HMDs) create planar images by beaming light from an optical fiber onto deflectable or rotating mirrors. This mirror-based approach has a critical limitation: the hardware of mirror scanners and grating deflectors must be significantly larger than the light beam diameter to avoid undesirable clipping or diffraction effects. Typically, attempting to reduce the size of a conventional display device reduces pixel count by loss of resolution or field-of-view (FOV) of the device. In this paper, we propose a HMD system utilizing a microfabricated 2D optical scanner controlled by a field-programmable gate array (FPGA) that overcomes the size limitations of other systems while maintaining high resolution.     

MEMS空间光调制器的研究现状与发展趋势

空间光调制器是自适应光学系统中用来实时校正波前畸变的关键器件,其发展水平能够反映整个自适应光学系统的水平。基于微电子机械系统(MEMS)技术的空间光调制器具有体积小、能耗低、驱动器单元密度高以及与集成电路工艺兼容性好等优点,而成为空间光调制器领域研究的热点。详细介绍了MEMS空间光调制器的研究现状和存在的主要问题,并分析了MEMS空间光调制器的未来发展趋势。     

Three-dimensional display rendering acceleration using occlusion camera reference images

Volumetric three-dimensional (3-D) displays allow the user to explore a 3-D scene free of joysticks, keyboards, goggles, or trackers. For non-trivial scenes, computing and transferring a 3-D image to the display takes hundreds of seconds, which is a serious bottleneck for many applications. We propose to represent the 3-D scene with an occlusion camera reference image (OCRI). The OCRI is a compact scene representation that stores only and all scene samples that are visible from a viewing volume centered at a reference viewpoint. The OCRI enables computing and transferring the 3-D image an order of magnitude faster than when the entire scene is processed. The OCRI approach can be readily applied to several volumetric display technologies; we have tested the OCRI approach with good results on a volumetric display that creates a 3-D image by projecting 2-D scene slices onto a rotating screen.     

Microelectromechanical systems and system-on-chip connectivity

The interconnection of microelectromechanical systems (MEMS) and other devices to a system-on-chip (SoC) implementation is described. MEMS technology can be used to fabricate both application specific devices and the associated micropackaging system that will allow for the integration of devices or circuits, made with non-compatible technologies, with a SoC environment. In the primary example presented, MEMS technology has been used to develop an acoustical array sensor for a hearing instrument application and also to provide a custom micropackaging solution suitable for in-the-ear canal implantation. A MEMS based modular micropackaging solution consisting of MEMS socket submodules and an insertable/removable microbus card has been developed to provide the necessary packaging and connectivity requirements. The modular socket concept can also be used for many other purposes, such as temporarily connecting a CMOS die to a SoC implementation of a die tester using MEMS based cantilevered bridge-type microspring contacts to provide connectivity to the die under test.     

3-D Displays and Signal Processing

In this article, main electronic 3-D display technologies from a signal processing perspective are overviewed. And the underlying physics, benefits, deficiencies of various displays are described. The general role of signal processing and provide specific examples of signal processing helping address certain display deficiencies are discussed. Challenges awaiting signal processing in quest of the ultimate 3-D experience is highlighted.     

3-D Mobile Display Based on MoirÉ-Free Dual Directional Backlight and Driving Scheme for Image Crosstalk Reduction

A novel micro-grooved structure of lightguides and a sequential driving scheme of light sources were demonstrated in achieving comparable image qualities of 3-D displays to that of 2-D displays. The modified distribution of micro-grooves not only locates viewing cones for respective eyes but also suppresses the moire pattern, which might occur when a periodic micro-grooved structure and a color filter are superimposed. The configuration of lightguides for a 1.8-in liquid crystal display (LCD) panel can yield acceptable 3-D perceptions at the viewing distance of 7-23 cm and the brightness uniformity of greater than 83%. In addition, the driving scheme of light sources in synchronization with parallax images can project images to the viewer's respective eyes sequentially. With the refreshing sub-frame rate of 190 Hz and double displaying parallax images, the image crosstalk of 3-D perceptions can be efficiently reduced for an LC response time of 7.0 ms.     

Cameras and display systems

We first discuss the position of cameras and displays in digital television systems. It is difficult to realize these devices in digital form so cameras and displays will remain analog for some time, even after television signal processing is implemented digitally. Nevertheless, the importance of camera and display in television systems will not diminish. These devices will always be key elements in the human interface. Second, we describe the current state of the art and future trends in camera and display technology. In addition to providing an overview of the charge coupled device (CCD), we discuss the digital technologies used in a CCD camera. We also provide an overview of currently available displays-CRT's, flat panel displays, projection displays, and head-mounted displays (HMD's)-and discuss future possible lines of research. Finally, we discuss camera and display technology as applied to digital television systems, including the use of these devices in a multimedia environment     

Reducing speckle artifacts in digital holography through programmable filtration

We propose a speckle reduction technique in electronic holographic display systems, where digital micro‐mirror array devices are used as spatial light modulators. By adopting a programmable filtration in a general 4‐f optic configuration, it is shown that the signal spectrum components in the frequency domain of a viewing‐window‐based holographic display system can be selectively filtered. Compared to the widely utilized single‐sideband filtration techniques in electronic holographic display systems, our proposed programmable filtration can be utilized to effectively reduce the speckles in the reconstruction of point‐cloud‐based computer‐generated holograms. Experimental results are presented to verify our proposed concept.     

Assessment of Mobile Technologies for Displaying Medical Images

We compared the characteristics of state-of-the-art mobile display systems based on reflective and transmissive liquid crystal displays (LCDs) and an organic light-emitting display with respect to physical characterization metrics and observer studies. Physical performance factors provided information on the differences among display technologies. Observer studies resulted in different system ranking between the task-based performance and user-preference approaches. The results of the physical characterization and preference study showed that the reflective LCD ranked lower. We also found that ambient illumination played a lesser role than previously seen in large-format workstation displays. The methodology developed in this study provides an initial insight into the comparison of alternative technologies for display of diagnostic images in small portable devices.      

扫描MIMO阵列近场三维成像技术

基于扫描阵列的近场3维成像是合成孔径雷达(SAR)3维成像技术在民用领域的一种重要应用形式。“多发多收(MIMO)-扫描”体制是该领域一种独特的成像方式。相比于“单发单收(SISO)”阵列,MIMO阵列具有成像质量好、阵元利用率高、对天线间隔要求宽松以及成本低等特点。该文分别从信号模型、成像算法、实验系统和成像结果等方面介绍了“MIMO-平面扫”和“MIMO-柱面扫”两种成像体制。所得结果充分展现了该成像技术在许多场景中的巨大应用潜力。      

Experiment Studies on Two-Dimension Terahertz Raster Scan Imaging

In this article, two kinds of THz two-dimension raster scan imaging methods are investigated. An array scanning system, which uses a Pyrocam III camera as the detecting device, and a point-wise scanning system, which adapts a Golay cell as the detector, are designed and tested with imaging experiments. The speed, scale and quality aspects of the two systems are analyzed. The experimental results show the point-wise scanning system has higher contrast and precision performances, with a lower scanning speed, and it could be used to scan detailed small-scale textures. The array scanning system has faster scanning speed, with lower resolution, and it could be deployed for rapid, large-scale scans.