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人类很早就认识到光可以传递信息,2000多年前我国就有了用光传递远距离信息的设施——烽火台;后来又有利用灯光闪烁传递信息的方法。1880年,发明家贝尔利用太阳光作光源,用硒晶体作为光接收器件,成功进行了光电话的实验,通话距离最远达到了213米。用大气作为传输介质,损耗大,而且无法避免外界干扰,光信号最多只能传送几百米远。人们不得不寻求可以在封闭状态下传送光信号的办法,例如利用波导管、棱镜、透镜折射的光束导管等。
Human beings have long realized that light can transmit information. In 2000, China had the facility of transmitting long-distance information with light - beacon towers. Later, it used the method of transmitting information with blinking lights. In 1880, the inventor Bell made use of sunlight as a light source and selenium crystal as a light-receiving device, and succeeded in carrying out the experiment of optical telephone with the distance as far as 213 meters. With the atmosphere as a transmission medium, loss, and can not be avoided outside interference, optical signals can only be sent up to a few hundred meters away. People have to find a way to transmit optical signals in the closed state, such as the use of waveguides, prisms, lens refraction of the beam guide tube.