The Lock-In Amplifier
摘要
The lock-in amplifier (LIA) is a common instrument in physics laboratories that can detect signals with extremely low signal-to-noise ratios. However, to really take advantage of its potential, a basic understanding of its operating principle is necessary. This chapter first introduces the phase sensitive detector (PSD) and evolves it into a lock-in amplifier. At the end of this chapter, the dual-phase lock-in amplifier is introduced and the I and Q signals are defined.