PDF《系统光学》

Application Report DLPA022CJuly

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

1 Overview of DMD Use in Projection Optical Systems

2 2 Projection Optical System Architectures

2 2.1 Telecentric Architectures

3 2.2 Nontelecentric Architectures

5 3 Projection Optical System Design Considerations

8 3.1 Illumination-System Components and Design Parameters

8 3.2 Projection-System Components and Design Parameters

13 4 System Performance Tuning Tips and Techniques

15 4.1 Contrast Ratio

15 4.2 Lumens

19 4.3 Optimizing Optical Costs

19 5 Alternate Light Sources and Systems

21 5.1 LED Sources

21 5.2 Laser Sources

24 5.3 Non-Imaging or Non-Projection Applications

25 List of Figures

1 Simplified Optical Function of a 12-Degree-Mirror-Tilt Device

2 2 Generic Telecentric Optical System Components Using a TIR Prism

3 3 Telecentric TIR Prism Design Layout for Minimum Package Height Due to Projection-Lens Offset

4 4 Nontelecentric Optical-System Components

6 5 Effect of Projection Offset on Illumination Angle, Nontelecentric Design, Side View

7 6 Nontelecentric Optical Layout for Flat Projector Using Reflective and Refractive Illumination Elements (Isometric View)7

7 Spatial 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)12

8 Frustrated TIR in TIR Prism Air Gap Should be Biased Toward Illumination Path

13 9 Scattering Incident-Beam Geometry

16 10 Scattered Light Into Projection Pupil for Off-State Mirror, 10-Degree Device

16 11 Contrast and Lumens as a Function of Illumination Angle for F/3 Telecentric System

17 12 Keystone Distortion for 0.9 XGA by Throw Ratio and Offset

20 1 DLPA022CJuly

2010 DLP? System Optics Copyright ? 2010, Texas Instruments Incorporated 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