第一章 红外辐射

些高灵敏度的探测器的出
现， 红外技术开始走向实用阶
段。
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Sir Frederick William Herschel (1738-1822) was born in Hanover, Germany, and became well known as both a musician and an astronomer. He emigrated to England in 1757, and with his sister Caroline, constructed telescopes to survey the night sky. Their work resulted in several catalogs of double stars and nebulae. William Herschel is perhaps most famous for his discovery of the planet Uranus in 1781, the first new planet found since antiquity. Caroline Herschel gained fame for the discovery of several comets.
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Herschel directed sunlight through a glass prism to create a spectrum - the "rainbow" created when light is divided into its colors - and measured the temperature of each color. He used three thermometers with blackened bulbs (to better absorb the heat) and placed one bulb in each color while the other two were placed beyond the spectrum as control samples. As he measured the temperatures of the violet, blue, green, yellow, orange and red light, he noticed that all of the colors had temperatures higher than the controls and that the temperature of the colors increased from the violet to the red part of the spectrum. After noticing this pattern, Herschel decided to measure the temperature just beyond the red portion of the spectrum in a region apparently devoid of sunlight. To his surprise, he found that this region had the highest temperature of all.
– 二、红外光谱
• 分子光谱，双原子分子的振—转光谱，多原子分子的红外 光谱。
– 三、红外辐射源
• 黑体等常用辐射源的介绍
– 四、红外线在大气中的传输
• 大气特性，大气吸收，大气散射。
– 五、红外探测器
• 红外探测器分类、噪声和性能参数；光子探测器、热探测 器；检测微弱信号的方法。
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– 六、红外调制
红外技术
• 红外技术是光电子学的重要组成部分， 属于光学的应用分支。
• 红外技术课是一门培养学生掌握红外基 本理论和相关的红外探测技术的应用基 础课。
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本课程内容
• 本课程分九章：
– 一、红外辐射
• 红外辐射的基本概念，辐射物理量和光谱辐射量，基尔霍 夫定律，黑体和普朗克公式，斯蒂芬—玻尔兹曼定律和维 恩位移定律。
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• 二、红外线
– 红外线也是电磁波，其波长范围从0.7微米到1000微米。
近红外 中红外 远红外
– 分为三个波段(International Commission on Illumination(CIE, 国际照明委员会))：
• Near-infrared (NIR，IR-A)：0.7um~1.4um
• 红外调制的方法及分类。
– 七、常用红外器件及应用
• 介绍常用的红外发射器件和红外检测器件及其应 用。
– 八、红外光学系统
• 在红外系统中离不开红外光学系统，其作用往往 是收集目标的红外辐射并传递到红外探测器。本 章介绍常用的红外光学系统及其特点
– 九、红外系统
• 本章将介绍两种常见的红外系统，红外探测系统 和热成像系统的工作原理及系统构成。
In the year 1800, William Herschel made another very important discovery. He was interested in learning how much heat passed through the different colored filters he used to observe the Sun and noticed that filters of different colors seemed to pass different levels of heat. Herschel thought that the colors themselves might contain different levels of heat, so he devised a clever experiment to investigate his hypothesis.
• 他做实现时，用热敏探测器(水银 温度计)发现了频率低于红光的 “不可见(invisible)光”，他称这 为“热射线（ calorific rays ）”。 后来，红外线的英语单词取Infrared意思是“below red”。
– 很长一段时间内，人们主要从
事红外线的本质方面的研究以
及红外光学材料研究，随着一
信息科学与工程学院 冯传胜 Email:fcs@
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• 1.1 红外线基本知识 • 1.2 基本辐射量与光谱辐射量 • 1.3 红外辐射基本定律
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1.1 红外线基本知识
• 一、红外现象的发现
– 1800年，英国天文学家S.W.赫 胥耳(Sir William Herschel)第 一次发现红外辐射现象。
Herschel performed further experiments on what he called the "calorific rays" that existed beyond the red part of the spectrum and found that they were reflected, refracted, absorbed and transmitted just like visible light. What Sir William had discovered was a form of light (or radiation) beyond red light. These "calorific rays" were later renamed infrared rays or infrared radiation (the prefix infra means `below'). Herschel's experiment was important not only because it led to the discovery of infrared, but also because it was the first time that someone showed that there were forms of light that we cannot see with our eyes. Herschel's original prism and mirror are on display at the National Museum of Science and Industry in London, England.
• Long wavelength infrared(LWIR，IR-C)：8um~15um
– 热成像的工作区域(人体热辐射波长10um)
• Far infrared(FIR，IR-C)：15um~1000um
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• 三、应用
– Night vision（微光夜视）
红外摄像机（英军押解伊战俘）
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• 参考文献：
– 1、《红外物理学》，张幼文。 – 2、《红外光学工程》，陈衡。 – 3、《光电检测技术》，罗先和等。 – 4、《光电检测技术》，雷玉堂等。 – 5、《红外光谱法》，董庆年。 – 6、《红外系统》，杨宜禾等。 – 7、《红外辐射测量基础》，周书铨。
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第一章 红外辐射 (Infrared Radiation, IR)
– 三、辐射强度I
• 点源与扩展源：
– 相对于被观测者(一般指探测器) 的张角很小的辐射源称为点源。 – 相对于被观测者的张角很大的辐 射源称为扩展源。
• 点源单位立体角内的辐射功率称为辐射强度。单 位为[瓦/球面度]。
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1.2 基本辐射量与光谱辐射量
• 1.2.1 基本辐射量
– 以电磁波形式传播的能量称为辐射能，用Q
表示，单位为[焦耳]。
– 红外探测器响应的往往是辐射能相对于时间
的速率，称为辐射功率(P)。