Difference between revisions of "Lock-in Amplifier"
| Line 6: | Line 6: | ||
== How Does a Lock-In Amplifier Work? == | == How Does a Lock-In Amplifier Work? == | ||
| − | Conceptually, a lock-in amplifier works by exploiting the orthogonality of sinusoidal functions. Use of a lock-in amplifier requires a clear reference signal at the frequency of the signal to be extracted. This reference signal is multiplied by the noisy input signal and then integrated over a set time. When sinusoidal functions are multiplied together and integrated over a significant amount of time, the result will be zero unless the two sinusoidal functions have the same frequency. For the output of a lock-in, this means that the contributions of all signals not at the reference frequency will be attenuated very close to zero | + | Conceptually, a lock-in amplifier works by exploiting the orthogonality of sinusoidal functions. Use of a lock-in amplifier requires a clear reference signal at the frequency of the signal to be extracted. This reference signal is multiplied by the noisy input signal and then integrated over a set time. When sinusoidal functions are multiplied together and integrated over a significant amount of time, the result will be zero unless the two sinusoidal functions have the same frequency. This is the before-mentioned orthogonality of sinusoidal functions. For the output of a lock-in, this means that the contributions of all signals not at the reference frequency will be attenuated very close to zero. This means the output is a DC signal showing the strength of the original signal at the reference frequency. |
Revision as of 13:04, 11 April 2016
What is a Lock-In Amplifier?
A lock-in amplifier is a type of amplifier used to extract quiet signals out of noisy data. High quality lock-in amplifiers can extract signals up to a million times quieter than the surrounding noise. The output of a lock-in amplifier is a DC signal showing the strength of the signal to be extracted.
How Does a Lock-In Amplifier Work?
Conceptually, a lock-in amplifier works by exploiting the orthogonality of sinusoidal functions. Use of a lock-in amplifier requires a clear reference signal at the frequency of the signal to be extracted. This reference signal is multiplied by the noisy input signal and then integrated over a set time. When sinusoidal functions are multiplied together and integrated over a significant amount of time, the result will be zero unless the two sinusoidal functions have the same frequency. This is the before-mentioned orthogonality of sinusoidal functions. For the output of a lock-in, this means that the contributions of all signals not at the reference frequency will be attenuated very close to zero. This means the output is a DC signal showing the strength of the original signal at the reference frequency.
