Multifrequency measurement

The Multifrequency Lockin Amplifier (MLA™) can run as many as 42 lock-in measurements in parallel, without interference between the different frequencies.  By carefully tuning of the multiple drive frequencies, the MLA™ can capture response at intermodulation products, or mixing products of many drive tones [1].  For example, a linear system driven with two pure tones will only respond at those two frequencies (top spectrum).  A nonlinear system will  generate response at  harmonics (integer multiples of the drive frequencies) and intermodulation products (integer linear combinations of the drive frequencies).  With appropriate choice of the drive frequencies we can generate many intermodulation products near a resonance, or in some frequency band where the response can be detected with good signal-to-noise ratio.  By measuring the intermodulation response we can reconstruct the nonlinearity, a technique called Intermodulation Spectroscopy [2].

[1] E. Tholén et al. Rev. Sci. Instrum. 82, 026109 (2011)

[2] C. Hutter et al.  Phys. Rev. Lett. 104, 050801 (2010)



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