复眼透镜提高液晶投影照明系统的能量利用率

照明系统是液晶投影仪的重要组成部分．它将直接影响到投影仪的光能利用率以及色彩等系统性能。对于复眼照明系统,复眼透镜的良好设计可以大人提高系统的能量利用率。在对液晶投影照明系统的原理进行分析的基础上,提出了两种复眼透镜的设计方案。两种方案均采用矩形子复眼,便于设计和加工。通过对复眼透镜中每个子复眼进行偏心以及改变其形状大小来提高系统能量利用率。计算机模拟结果表明,两种设计方案与传统设汁相比,在光能利用率上分别提高了16．5％和26．3%,并且具有较高的均匀性。最后,还对两种复眼透镜的设计方案进行了分析和比较。     

声光栅正弦结构光投射器的光学系统设计

针对一种新型的声光波干涉测量技术,对声光栅正弦结构光投射器的三维测量工作原理进行了系统的分析,讨论了影响投射器光学系统结构的因素和影响接收屏上的光照度的因素,并进行了光学系统设计。在优化设计过程中,采用了限制光线最大入射角的方法,达到控制投射系统的球差和保证接收屏上照明均匀的要求。所设计的声光栅正弦光投射器具有很好的成像质量。应用该系统对在500mm处的石膏像上投射干涉条纹,可以得到能量比较均匀、变形量很小的干涉条纹图,利用该条纹图和相关的算法可以对具有复杂几何形状的物体进行有效的三维测量。     

一种色度自适应投影标记点的选取方法

近年来,对物体的颜色显现力、光源光谱功率分布和自身表面反射光谱三者的定量关系方面的研究备受大家关注。在三维扫描测量领域,由于颜色特征具有反映物体材料和纹理等丰富信息的优势,提出了一种主要由彩色相机、投点光源和PC机组成的色度自适应投点仪结构,其中数字微镜(DMD)作为投点光源的核心元件用于调制R,G,B 三个LED光源的光谱功率分布。然而主动式标记点的颜色显现力因受未知反射光谱投影接受面的影响,其颜色特征往往难以识别和区分。为了提高投影标记点与不同反射光谱的投影接收面作为背景的分辨力,描述了一种色度自适应投影标记点的选取方法。在高维线性反射光谱建模的基础上,用光谱响应的方法对彩色投点仪设备特征化,以解决三通道彩色相机设备特征化精度低的问题。并通过样本训练为高维线性反射光谱的求解提供条件约束。继而,在CIE1931色度坐标空间下,选取与投影接收面背景色度坐标欧氏矩最大的色度坐标点。根据投点仪设备特征化结果,推导其LED最优设定值。最后,采用24孟塞尔色卡作为被投影对象,主动标记点与色块的色差作为其颜色显现力的评价参数,通过与激光二极管投点仪做对比性实验。实验结果表明对各不同色度的投点接受面,提出的色度自适应投影标记点的选取方法均有较好表现。     

用投影仪检控边厚差和中心偏差

用投影仪检控边厚差和中心偏差的方法,解决了特别小的不可见光透镜、可见光透镜在生产过程中控制边厚差及中心偏差的验收问题。本文还介绍了投影屏上的分划形式,以及调试放大投影像进行测量的方法。     

Analysis of speckle reduction based on theory of optical eigenfunction

The principle of optical eigenfunction is used in the analysis of speckle reduction in laser projection display.When the moving diffiuser is used in the speckle reduction approach,the speckle contrast is decided by both the degree of freedom (DOF) of the projector and the area of resolving cell of the eyes on the screen.It can gain high DOF of the projector by increasing the space-bandwidth product,i.e.,adopting a projection lens with a high numerical aperture or a large viewing field.The best scheme is equalizing the DOF of the scattering wave from a moving diffiuser to that of the projection lens.The experimental results are in accordance with the conclusion drawn by optical eigenfunction.     

An eye-tracking and head-control system using movement increment-coordinate method

In this paper a novel design which combines an eye-tracking device with a head gesture control module is discussed. In the eye-tracking mode, the user wears goggles, and two tiny CCD cameras capture the eye image from the screen with the help of a video capture card. In the head gesture control mode, a light source projector is turned on, and the CCD camera detects the position of the light source. The locations of the spots on the screen and on the image pupil of the eye image are calculated, compared with the previous point and are subsequently mapped to the point on the screen. The movement increment-coordinate control is also discussed, which could improve the ease of use of the computer.     

用于投影机的发光二极管照明单元

目前的投影机光源——高压汞灯存在寿命短、色温高、存在有害光线、发热集中等缺点,严重制约了投影机进入家庭应用领域。发光二极管的最近发展为其作为高压汞灯的替代光源提供了可能性。提出了一种由一个发光二极管、一个准直镜、一个前蝇眼透镜和一个后蝇眼透镜组成的用于投影机的发光二极管照明单元,由数个照明单元加上会聚透镜则构成一个基本的照明系统。发光二极管的发光经准直镜压缩光束发散角后被前蝇眼透镜分割为多个细光束,会聚透镜将每个细光束都叠加会聚到显示芯片上,实现光能量的会聚和光场再分布．以满足投影机对光通量和光场均匀性等方面的要求,后蝇眼透镜用于与后续光路的匹配。作为照明单元的一个应用实例,文中分析了一种单片式硅上液晶投影机。     

Sketch of a New 5-dimensional Projective Unified Field Theory — Physical Predictions and Applications

Some years ago the author published a new version of a 5-dimensional Projective Unified Field Theory unifying gravitation, electromagnetism and scalarism. Geometrically this theory is mainly based on following 5-dimensional assumptions: symmetric metric tensor, Riemannian curvature, torsion, projector property of the basic quantities. A particular projection procedure leads from the 5-dimensional field equations and conservation laws to 4-dimensional ones. The 4-dimensional scheme of equations is interpreted physically. Special interest is taken in the energy projector, describing an electrically charged perfect fluid. Several physical predictions and applications are presented.     

用于中小型飞行模拟器的球带幕投影镜头的光学设计

针对现有沉浸式飞行模拟器进一步小型化和低成本化的需求,设计了一款应用于中小型飞行模拟器的球带幕投影镜头。论文确定了投影方案中各部件(球带幕、投影机、投影物镜)的关键参数,设计的球带幕投影镜头具有172°的视场角和6∶1的反远比,将一台装有该镜头的投影机置于银幕上沿就可以将画面投满整个球带幕。文中给出了大视场、大反远比光学系统的构造方法,对大视场非相似成像系统中的畸变、场曲和相对照度进行了分析和讨论,并给出了改善照度均匀性的有效途径。该镜头以8片透镜的低成本结构满足了4 k分辨率的高质量投影需求,在奈奎斯特频率185 lp/mm处全部视场的MTF值均达到了0.4以上,且具有良好的工艺性。     

A fast and accurate calibration method for the structured light system based on trapezoidal phase-shifting pattern

Calibration plays an important part in the structured light system. It used to be regarded as time-consuming, expensive and hard to implement. In this paper, we introduce a novel and fast method to calibrate the structured light system by using the camera to control the projector to “capture” images. Firstly, we projected just six trapezoidal grayscale pattern to establish the corresponding pixel between the camera and the projector, then we converted the camera image to its corresponding projector image. Thus the structured light system can be easy controlled by the camera calibration. Experiments showed that the present calibration method is fast, easy and accurate.     

Research on DMD infrared scene projector with a high contrast ratio infrared prism design

In this paper a single-DMD infrared scene projector with a high contrast ratio prism design of the illumination optical system is presented. By using the innovative infrared three-element TIR prism group, the off-state and flat-state light that reflected by the DMD could be all steered away from the projection lens. The contrast ratio and optical efficiency has been improved with this three-element TIR prism as the light-separator. This DMD infrared scene projector also features low-profile and compact structure. The illumination and projection optical systems are proved to be of great efficient light utilization. In this letter we analyze the impacts of optical efficiency on temperature simulation. This architecture with three-element TIR prism added could be used in IRSP based single-DMD to improve contrast and optical efficiency.     

High-accuracy measurement for small scale specular objects based on PMD with illuminated film

In this paper we describe an approach to measure small glossy objects by illuminated film based on Phase Measuring Deflectometry (PMD) system. In this setup, the standard sinusoidal fringe patterns are produced by the photographic film frame (135-film), which is illuminated from behind using LED and diffuser, instead of the well-known LCD monitor plane or digital projector. This setup can avoid the influence of electronic noise and screen refreshing, and fulfill the test of small objects in low cost. Moreover the system is easily calibrated with its vertical setup. With the experiments of measuring a plastic contactless smartcard and a metal plate, it is proven that the setup can reach sub-micrometer accuracy with respect to the data of the Wyko white light interferometer. This setup will be promising in the small scale measurement field.     

Compact compound-eye projector using superresolved projection

We propose a compact compound-eye projector using superresolved projection. The optics are composed of multiple small suboptics (units) to reduce their thickness in the projector. Each of the suboptics adds a subpixel shift to a projected image for superresolved projection and has a color filter or a dispersive element for multicolor projection. The projected images in the units are determined via a model of the system in preprocessing. The images are projected by the suboptics and superimposed on a screen. In this Letter, we describe the system model and show the simulation results.     

Flexible digital projector calibration method based on per-pixel distortion measurement and correction

When a digital projector is applied in high precision applications, the intrinsic parameters and distortion characteristics should be calibrated precisely. In this paper, a flexible full-field projector calibration method is proposed without any approximate distortion model. With planar homography theory and fringe projection technique, the projector distortion characteristic on each pixel can be measured independently and an initial distortion map is generated. The intrinsic parameters are calibrated afterwards. Then, the initial distortion map can be refined by correcting the non-perpendicularity between the optical axis and image plane. The original pattern to be projected is corrected with the refined distortion map. Thus, the calibrated projector can be regarded as an ideal projector conforming to the pinhole model. Experimental results show a nearly ideal residual map for the corrected projection pattern. In addition, the proposed calibration method is flexible without any sophisticated ancillary equipment or complicated procedure.     

光学三维扫描仪光强传递函数的测量和校正

由于数字光栅投影仪的光强传递函数对于正弦投影条纹的质量以及相位测量精度起着至关重要的作用,本文提出了一种校正光学三维扫描仪光强传递函数的新方法。首先,分析了由于投影仪非线性响应引起的光栅谐波的相位测量误差;然后,通过投影一组不同灰度级的图像,并利用光功率计测出数字投影仪投出图像的亮度。接着,通过分析得到数字投影仪的非线性响应特性曲线,再经过数据处理,即可获得投影仪的光强传递函数;最后,对光强传递函数进行反函数逆变换,得到一个校正后的非正弦光栅,利用投影仪对该光栅的投影即可在被测物体表面上获得一个正弦光栅。数字投影仪对标准平板的测量结果表明,校正前平均误差为0.71 mm,校正后为0.55 mm;对于标准量块的测量,校正前的平均误差为0.62 mm,校正后为0.15 mm。上述结果表明,本文提出的方法可以减小由于系统非线性响应引起的测量误差并提高测量精度。     

Kamlah expansion and gauge theories

In Yang-Mills theories, variational calculations of the Rayleigh-Ritz type face the problem that on the one hand, calculability puts severe constraints on the space of test wave functionals; on the other hand, the test wave functionals have to be gauge invariant. The conflict between the two requirements can be resolved by introducing a projector. In this paper, we present an approach to approximating the projector in a way known and successfully employed in nuclear physics: the Kamlah expansion. We discuss it both for electrodynamics and for Yang-Mills theories to leading order in a perturbative expansion, and demonstrate that the results are compatible with what one would expect from perturbation theory.     

中波红外景象投影光学系统消热差设计

针对红外成像系统性能测试与评估的应用需求,设计了一套基于数字微镜器件的消热差的中波红外景象投影光学系统.探讨了红外视景仿真用投影光学系统的像差特性和设计方法,并对投影系统的无热化进行了分析.采用分光板和补偿板方案,解决了大相对孔径条件下投影系统的远心照明分光和像差平衡问题,提高了分辨率和均匀性,增大了视场.系统由远心投...     

A novel device for head gesture measurement system in combination with eye-controlled human–machine interface

This study describes the design and combination of an eye-controlled and a head-controlled human–machine interface system. This system is a highly effective human–machine interface, detecting head movement by changing positions and numbers of light sources on the head. When the users utilize the head-mounted display to browse a computer screen, the system will catch the images of the user's eyes with CCD cameras, which can also measure the angle and position of the light sources. In the eye-tracking system, the program in the computer will locate each center point of the pupils in the images, and record the information on moving traces and pupil diameters. In the head gesture measurement system, the user wears a double-source eyeglass frame, so the system catches images of the user's head by using a CCD camera in front of the user. The computer program will locate the center point of the head, transferring it to the screen coordinates, and then the user can control the cursor by head motions. We combine the eye-controlled and head-controlled human–machine interface system for the virtual reality applications.     

结构光三维测量系统中投影仪标定技术研究

投影仪标定是单摄像机单投影仪结构光三维测量中的基础。采用双面标定块实现投影仪的标定。标定块正面为黑底白色圆点图案,通过Tsai两步法及非线性优化完成摄像机标定。背面为反射率均匀的白色平面,由投影仪投影双方向高亮度的直线来生成特征点。针对特征点三维坐标难以确定的问题,采用了两种方法:一是依靠摄像机标定结果;二是结合正面圆点图案,利用交比不变性获取更多的有效输入数据。标定设备简单,操作方便。实验结果证明具有较理想的标定精度。