Pulse width Modulation device is a circuit which can produce square wave signal with fixed period and adjustable pulse duration ratio (pulse width).

脉宽调制器是一种能够产生周期固定而占空比(脉宽)可调的方波信号的电路。

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And a theoretical model is established to expound the variation of pulse duration and the modulation on the pulse envelope similar to the diffraction characteristics in spatial domain.

通过与光束的空间传输特性类比解析了光栏宽度变化引起的脉宽变化以及脉冲轮廓出现时间衍射调制现象；

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