Discriminator: a device that converts a property of an input signal such as frequency or phase into an amplitude variation depending on how the signal differs from a standard or reference signal.
Using the optical chopper to modulate the detected light to make it related to the reference squarewave signal is a common method of locking phase detection of weak signals.
其中利用光学斩光器对被测光进行调制使其与方波参考信号相关是对微弱光信号进行锁相检测的一种常用方法。
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We present a method for preserving time-invariant phase relationships, through introduce a third signal as a reference, when ratios are taken between two complex signals that are harmonically related.