DLP 光学系统

Application Report DLPA022–July 2010

DLP™System Optics ABSTRACT

This application note describes typical architectures for optical systems employing a single DMD device for projection applications,primarily for small portable projectors.Pros and cons of architectures are discussed in general terms.Front-and rear screen applications are discussed briefly.Techniques and trades for maximizing critical system performance parameters,defined by the application,are discussed.Unique considerations for DMD devices in optical systems are addressed.A general discussion of image quality and specific design metrics for acceptable performance is included.

Note the majority of this document describes the use of the DMD in a projection optical system,and the DMD is designed with this application in mind.However,there are many other ways to use the DMD to manage and steer light energy.This document addresses some of the non-projection applications briefly,but cannot anticipate all uses.

Contents 1Overview of DMD Use in Projection Optical Systems ..................................................................22Projection Optical System Architectures .................................................................................22.1Telecentric Architectures ..........................................................................................32.2Nontelecentric Architectures ......................................................................................53Projection Optical System Design Considerations .....................................................................83.1Illumination-System Components and Design Parameters ...................................................83.2Projection-System Components and Design Parameters ...................................................134System Performance Tuning Tips and Techniques ...................................................................154.1Contrast Ratio .....................................................................................................154.2Lumens ............................................................................................................194.3Optimizing Optical Costs ........................................................................................195Alternate Light Sources and Systems ..................................................................................215.1LED Sources ......................................................................................................215.2Laser Sources .....................................................................................................245.3Non-Imaging or Non-Projection Applications .. (25)

List of Figures 1Simplified Optical Function of a 12-Degree-Mirror-Tilt Device ........................................................22Generic Telecentric Optical System Components Using a TIR Prism ...............................................33Telecentric TIR Prism Design Layout for Minimum Package Height Due to Projection-Lens Offset ...........44Nontelecentric Optical-System Components ............................................................................65Effect of Projection Offset on Illumination Angle,Nontelecentric Design,Side View ..............................76Nontelecentric Optical Layout for Flat Projector Using Reflective and Refractive Illumination Elements (Isometric View)

.............................................................................................................77Spatial Irradiance Distribution of a Small-Arc Lamp at Focus of Elliptical Reflector Before Integration (left,at rod input)and After Integration (right,at rod output)..............................................................128Frustrated TIR in TIR Prism Air Gap Should be Biased Toward Illumination Path ...............................139Scattering Incident-Beam Geometry ....................................................................................1610Scattered Light Into Projection Pupil for Off-State Mirror,10-Degree Device .....................................1611Contrast and Lumens as a Function of Illumination Angle for F/3Telecentric System .........................1712Keystone Distortion for 0.9XGA by Throw Ratio and Offset .. (20)

应用报告ZHCA631 － 2010 年 7 月DLP™ 系统光学

摘要

本应用文档说明了面向投影应用（主要是小型便携式投影机）的采用单一DMD 器件的光学系统的典型架构。文章概括地阐述了相关架构的优缺点。简要地讨论了前投式和背投式屏幕应用。探讨了用于最大限度地提升应用规定的关键系统性能参数的方法和技巧。论述了将 DMD 器件应用于光学系统的独特考虑因素。文中还综合讨论了图像质量以及针对可接受性能的具体设计指标。请注意，本文件的大部分内容所描述的均是 DMD 在投影光学系统中的运用，而且 DMD 的设计是以该应用为主要考虑因素的。不过，使用 DMD 来管理和引导光能还有许多其他的方法。本文件简要地论及了某些非投影类应用，但无法预料所有的用途。目录

1DMD 在投影光学系统中的使用概述 ........................................................................................22投影光学系统架构 .................................................................................................................22.1 平行光路架构 ...............................................................................................................32.2 非平行光路架构............................................................................................................53投影光学系统设计考虑因素....................................................................................................83.1 照明系统组件和设计参数 ...............................................................................................83.2 投影系统组件和设计参数 ...............................................................................................134系统性能调优技巧与方法 ........................................................................................................154.1 对比度比 ......................................................................................................................154.2 流明 .............................................................................................................................194.3 优化光学成本 ................................................................................................................195替代光源和系统 .....................................................................................................................215.1 LED 光源 ......................................................................................................................215.2 激光光源 ......................................................................................................................245.3 非成像或非投影应用 ......................................................................................................25插图清单1一个 12°微镜的简化光学功能 ................................................................................................22采用 TIR 棱镜的通用平行光路光学系统组件 ..............................................................................33针对因投影透镜偏移引起的最小封装高度的平行光路 TIR 棱镜设计布局 ..........................................44非平行光路光学系统组件 .......................................................................................................65投影偏移对于照明角度的影响，非平行光路设计，侧视图..............................................................76针对采用反射式和折射式照明元件之平面投影机的非平行光路光学系统布局（等轴视图） .......................................................................................................................77积分前（左侧，在柱输入）及积分后（右侧，在柱输出）小型弧光灯在椭圆形反射器焦点处的空间辐射照度分布 ...........................................................................................................................128TIR 棱镜空气间隙中的受抑全内反射 (TIR) 应偏向照明路径 ...........................................................139散射入射光束几何结构 ...........................................................................................................1610散射光进入用于Off 态微镜的投影光瞳，10° 器件....................................................................1611对比度和流明与照明角度的函数关系（针对 F/3 平行光路系统）........................................................17120.9 XGA 的梯形失真（依据投射比和偏移）. (20)