- 1、本文档共10页,可阅读全部内容。
- 2、原创力文档(book118)网站文档一经付费(服务费),不意味着购买了该文档的版权,仅供个人/单位学习、研究之用,不得用于商业用途,未经授权,严禁复制、发行、汇编、翻译或者网络传播等,侵权必究。
- 3、本站所有内容均由合作方或网友上传,本站不对文档的完整性、权威性及其观点立场正确性做任何保证或承诺!文档内容仅供研究参考,付费前请自行鉴别。如您付费,意味着您自己接受本站规则且自行承担风险,本站不退款、不进行额外附加服务;查看《如何避免下载的几个坑》。如果您已付费下载过本站文档,您可以点击 这里二次下载。
- 4、如文档侵犯商业秘密、侵犯著作权、侵犯人身权等,请点击“版权申诉”(推荐),也可以打举报电话:400-050-0827(电话支持时间:9:00-18:30)。
查看更多
外文原文二2015精选
外文原文二
Photoelectric Sensing
Photoelectrics: The Past
Albert Einstein first gave momentum to photoelectric science when he published his Nobel Prize winning paper on quanta in 1905. His theory explained the photoelectric effect, which had been observed but not fully explained by scientists for many years. It was a bold proposition that light energy travels through space in concentrated bundles (now called photons). Photons that strike a material (especially a metal surface) liberate photoelectrons, and the energy from those photoelectrons may be used to create current flow. Careful experiments by R.A. Millikan in 1914 and 1916 confirmed Einsteins theory.
A growing understanding of the photoelectric effect over the next fifty years led to the development and evolution of various optoelectronic devices. The first applied photoelectric device was the photoemissive cell or phototube, whose primary application was in movie sound reproduction. The fragile nature of phototubes, however, limited their use in industrial sensing.
In the late 1940s, the photoconductive cell (photocell) was developed for use in light sensing circuits. Although it was originally manufactured in a fragile glass envelope, the photocell did have the advantage of being much smaller and simpler in function than the phototube.
From the beginning, photoelectric receivers took on the shape of small, round metal barrels, with a collimating lens on one end and a cable exiting the opposite end. The cable connected the photocell to a tube-type amplifier. Small incandescent bulbs, protected in matching metal barrels, were the opposing light source. These smaller and more rugged devices made beam-break (opposed) photoelectric sensing an attractive mode for many industrial applications, and were the forerunners of todays sensor designs.
The key to sensing success in the days of incandescent photoelectrics was to make the photocell see the light from its source without gathering any stray (ambient) light. This
您可能关注的文档
- 复习专题 病句的辨析和修改精选.doc
- 复习古诗词精选.doc
- 复习册页申精选.doc
- 复习资料11 名著导读精选.doc
- 复习方法指导精选.pdf
- 复习题1精选.ppt
- 复习题s精选.doc
- 墨与色的韵味Microsoft PowerPoint 演示文稿精选.ppt
- 复习:古代中国的科技与文学艺术精选.ppt
- 复旦大学 计算机院 赵一鸣 离散数学 图论习题精选.ppt
- 运动风格趋势:轻量化户外 2025 S S.pdf
- 数字乡村建设村村通广播应用方案.pdf
- 高盛-日本市场策略 Japan Strategy Flash 1Q325 earnings summary Double-digit (%) profit growth as results largely surprised upwards 0820 2024.pdf
- CEEM《全球智库半月谈》(总第286期).pdf
- 智慧物流概论微课课件第4章智慧物流信息平台.pdf
- 数字乡村公共安全综合平台项目解决方案.pdf
- 智慧物流概论微课课件第7章智慧物流包装.pdf
- 【案例】”啤酒之王“的智慧物流探索之路.pdf
- 数字连江城市数字基座(一期)和数字乡村示范点建设项目.pdf
- 智慧物流概论微课课件第1章智慧物流概述.pdf
文档评论(0)