lock-in amplifier


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lock-in amplifier

[′läk‚in ′am·plə‚fī·ər]
(electronics)
An amplifier that uses some form of automatic synchronization with an external reference signal to detect and measure very weak electromagnetic radiation at radio or optical wavelengths in the presence of very high noise levels.
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.
References in periodicals archive ?
It comes with the vendor's cryogen-free bottom-loading cryostat (the OptistatDry BLV), an MFLI lock-in amplifier from Zurich Instruments, a specially designed ESD break-out box, and high-quality cables.
We have significantly enhanced the detection sensitivity of the eddy current method by detecting and demodulating the differential signal of the two coils induced by rail defects, using a digital lock-in amplifier algorithm.
The block diagram of a typical lock-in amplifier is shown in Figure 2.
The reflected scattered signal is diverted to a wideband homodyne quadrature mixer and the in-phase and quadrature IF (10 to 100 kHz) voltages are detected by a lock-in amplifier. The signal levels from the in-phase and quadrature channels of the mixer for a typical microwave circuit with 10 dBm input power range from 10 [[micro]volt] to 10 mV when measured with a lock-in amplifier with a 10 dB gain preamplifier.
A lock-in amplifier with two detectors--a dual-phase lock-in--has two references in quadrature and determines both the cosine of the phase difference as well as a separate sine term.
The photodiode signal is analyzed by a dual-channel lock-in amplifier, referenced by the driving frequency of the rf coils produced by a voltage controlled oscillator (VCO).
The FLL functional blocks consist of an RF generator, lock-in amplifier and the rubidium physics package.
The system is based an RF comb-generator that modulates laser light at 2.46 GHz and mixes the detected power to a 123 MHz frequency measurable by a low-phase-noise RF lock-in amplifier. The PMD resolution of the system appears to be limited by the phase noise of the lock-in amplifier itself.
In spite of the high performance lock-in amplifier used as a second stage signal-amplifier, the signal-to-noise ratio must be optimized for the output of the photocurrent measuring preamplifier.