The lock-in amplifier: what is it for? how to build one?

Torzo, G.; Delfitto, G.

doi:10.1590/1806-9126-rbef-2022-0072

Cited by 4 publications

(4 citation statements)

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“…For an integration time τ < 1 s, a drop-off appears due to the cut-off frequency of the lock-in amplifier low pass filter. The Allan deviation is trustworthy for an integration time τ that is at least five times greater than the lock-in amplifier time constant [ 16 ]. As shown in Figure 9 , for τ > 500 ms, the curves have the classical τ −1/2 slope indicating dominant white noise.…”

Section: Photoacoustic Sensingmentioning

confidence: 99%

Highly Sensitive Capacitive MEMS for Photoacoustic Gas Trace Detection

Seoudi

Charensol

Trzpil

et al. 2023

Sensors

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An enhanced MEMS capacitive sensor is developed for photoacoustic gas detection. This work attempts to address the lack of the literature regarding integrated and compact silicon-based photoacoustic gas sensors. The proposed mechanical resonator combines the advantages of silicon technology used in MEMS microphones and the high-quality factor, characteristic of quartz tuning fork (QTF). The suggested design focuses on a functional partitioning of the structure to simultaneously enhance the collection of the photoacoustic energy, overcome viscous damping, and provide high nominal capacitance. The sensor is modeled and fabricated using silicon-on-insulator (SOI) wafers. First, an electrical characterization is performed to evaluate the resonator frequency response and nominal capacitance. Then, under photoacoustic excitation and without using an acoustic cavity, the viability and the linearity of the sensor are demonstrated by performing measurements on calibrated concentrations of methane in dry nitrogen. In the first harmonic detection, the limit of detection (LOD) is 104 ppmv (for 1 s integration time), leading to a normalized noise equivalent absorption coefficient (NNEA) of 8.6 ⋅ 10−8 Wcm−1 Hz−1/2, which is better than that of bare Quartz-Enhanced Photoacoustic Spectroscopy (QEPAS), a state-of-the-art reference to compact and selective gas sensors.

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Section: Photoacoustic Sensingmentioning

confidence: 99%

Highly Sensitive Capacitive MEMS for Photoacoustic Gas Trace Detection

Seoudi

Charensol

Trzpil

et al. 2023

Sensors

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“…Simultaneously, phase alignment technology is extensively employed in precision measurements [17,18] and can be categorized into two structures. One approach [19][20][21] employs a dual-channel method for phase alignment, where a pair of orthogonal reference signals is multiplied by the input signal to calculate the current phase difference and ultimately achieve phase alignment.…”

Section: Introductionmentioning

confidence: 99%

Research and Implementation of a Demodulation Switch Signal Phase Alignment System in Dynamic Environments

Xue,

Yu,

Sui

et al. 2023

Sensors

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In the space gravitational wave detection mission, inertial sensors play the role of providing an inertial reference for the laser interferometric measurement system. Among them, the capacitance sensor serves as the core key technology of the inertial sensor, used to measure the relative position of the test mass (TM) in the electrode cage. The capacitance sensor utilizes synchronous demodulation technology to extract signals from the AC induction signal. When the phase of the demodulation switch signal is aligned, the synchronous demodulator can most effectively filter out noise, thus directly influencing the performance of the capacitance sensor. However, since the TM is in a suspended state, the information read by the capacitance sensor is dynamic, which increases the difficulty of demodulation phase alignment. In light of this, a method is proposed for achieving the phase alignment of the demodulation switch signal in a dynamic environment. This is accomplished by adjusting the phase of the demodulation switch signal, and subsequently computing the phase difference between the AC induction signal and the demodulation switch signal. At the same time, a measurement and evaluation method for phase deviation is also proposed. Ultimately, an automatic phase alignment system for the demodulation switch signal in dynamic environments is successfully implemented on an FPGA platform, and tests are conducted on a hexapod PI console platform to simulate dynamic environments. The experimental results demonstrate that the system accurately achieves phase alignment in the static environment, with a phase deviation of 0.1394 rad. In the simulated dynamic environment, the phase deviation is 0.1395 rad.

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“…First, it is necessary to introduce the basic working mechanism of a lock-in amplifier (LIA). (58) The LIA can be seen not only as a scientific instrument but a signal manipulation principle. The idea behind it is to introduce a modulation in the signal G(t) with frequency f r , or to make use of a natural modulation frequency of the system.…”

Section: Lock-in Analysis Of Ta Signalmentioning

confidence: 99%

“…In this manner, frequencies that only contain noise are eliminated, and usually it is possible to extract high-quality data even from noisy signals. (58) The way this is possible can be explained by considering the Fourier series expansion of a periodic function G(t) as a sum of oscillating terms of frequency f r :…”

Section: Lock-in Analysis Of Ta Signalmentioning

confidence: 99%

Ultrafast pump-probe platform for broadband and polarization-resolved characterization of materials: case study of octupolar push-pull azobenzenes

Garcia

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Eu sei o que estou fazendo. Antes mesmo de ser mestre, Com esse azobenzeno, eu fiz um último teste. Eu excitei num só atto um gato vivo e morto. Feito assim só por um femto, Causando enorme lamento (ou alegramento). E depois de mais um pico, Morro abaixo num trupico, Uma interseção dramática. Forte, não-adiabática. Que do avesso e de repente Se tornou tão diferente Cisfigura metaestável, Com um remolejo amável. Tal movimento intrincado Me rendeu até um mestrado.

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The lock-in amplifier: what is it for? how to build one?

Cited by 4 publications

References 0 publications

Highly Sensitive Capacitive MEMS for Photoacoustic Gas Trace Detection

Highly Sensitive Capacitive MEMS for Photoacoustic Gas Trace Detection

Research and Implementation of a Demodulation Switch Signal Phase Alignment System in Dynamic Environments

Ultrafast pump-probe platform for broadband and polarization-resolved characterization of materials: case study of octupolar push-pull azobenzenes

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