Signal-to-noise ratio in lock-in amplifier synchronous detection: A generalized communications systems approach with applications to frequency, time, and hybrid (rate window) photothermal measurements
- 1 November 1994
- journal article
- research article
- Published by AIP Publishing in Review of Scientific Instruments
- Vol. 65 (11), 3309-3323
- https://doi.org/10.1063/1.1144568
Abstract
Detailed analytical models of signal‐to‐noise ratios (SNR) of the conventional frequency domain (FD) and time domain (TD) photothermal measurement methodologies are developed and compared to the rate‐window photothermal method, both theoretically and experimentally. The conclusions of this study demonstrate that the lock‐in amplifier (LIA) rate‐window measurement mode in general, and the digital LIA mode, in particular, exhibits superior SNR to both the conventional frequency‐scanned LIA FD method and to the transient, time‐averaged TD method. Between the pulse‐duration‐scanned and pulse‐repetition‐period scanned rate‐window methodologies, the former clearly exhibits superior SNR. The theoretical conclusions are in agreement with experimental SNRs using the implementation of the foregoing measurement methodologies with simple infrared photothermal radiometric setups.This publication has 16 references indexed in Scilit:
- A comparison between conventional photothermal frequency scan and the lock-in rate window method in measuring thermal diffusivity of solidsReview of Scientific Instruments, 1994
- Highly resolved separation of carrier- and thermal-wave contributions to photothermal signals from Cr-doped silicon using rate-window infrared radiometryJournal of Applied Physics, 1993
- Photothermal rate-window spectrometry for noncontact bulk lifetime measurements in semiconductorsJournal of Applied Physics, 1993
- Thermal-diffusivity measurements of ultrahigh thermal conductors with use of scanning photothermal rate-window spectrometry: Chemical-vapor-deposition diamondsPhysical Review B, 1992
- Lock-in rate-window thermomodulation (thermal wave) and photomodulation spectrometryReview of Scientific Instruments, 1992
- Accurate broadband square-to-triangle convertorElectronics Letters, 1977
- Phase sensitive detection as a means to recover signals buried in noiseJournal of Physics E: Scientific Instruments, 1975
- A correlation method for semiconductor transient signal measurementsJournal of Applied Physics, 1975
- Measurement of Low Light Intensities by Synchronous Single Photon CountingReview of Scientific Instruments, 1966
- An Alternative Approach to the Realization of Network Transfer Functions: TheN-Path FilterBell System Technical Journal, 1960