Physics and Astronomy

Physics Seminar Series

Lock-In Detection

presented by Hank Norton C'20

Tuesday, March 12, 7:30 - 8:30pm, Woods Labs 216


Lock-in amplifiers are used to detect and measure very small AC signals all the way down to a few nanovolts. Signals and noise are all around us in the world; sometimes a signal of interest can become so buried in overwhelming noise that it may seem beyond retrieval. But lock-in detection is precisely the process of extracting a desired signal out of the depths of noise by means of a technique known as phase-sensitive detection, which singles out the component of the signal at a specific reference frequency and phase. Any signals or noise that are not at this specific frequency are rejected and filtered out, and so the desired signal clearly stands out.

These types of measurements can work even if noise levels are 1000 times larger than the signal of interest. I will discuss the fundamentals of the lock-in technique and illustrate its power with results from my recent experiments and simulations.


Hank Norton, C’20, is a junior physics major at the University of the South from Ringgold, GA. He is a retired Sewanee basketball player and a member of the Sewanee chapter of the Society of Physics Students.

For more informationProf. Eugene Donev (931) 598-3154 |



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