Section 60
Chapter 59,405

A simplified digital lock-in amplifier for the scanning grating spectrometer

Wang, J.; Wang, Z.; Ji, X.; Liu, J.; Liu, G.

Review of Scientific Instruments 88(2): 023101


ISSN/ISBN: 1089-7623
PMID: 28249479
DOI: 10.1063/1.4974755
Accession: 059404871

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For the common measurement and control system of a scanning grating spectrometer, the use of an analog lock-in amplifier requires complex circuitry and sophisticated debugging, whereas the use of a digital lock-in amplifier places a high demand on the calculation capability and storage space. In this paper, a simplified digital lock-in amplifier based on averaging the absolute values within a complete period is presented and applied to a scanning grating spectrometer. The simplified digital lock-in amplifier was implemented on a low-cost microcontroller without multipliers, and got rid of the reference signal and specific configuration of the sampling frequency. Two positive zero-crossing detections were used to lock the phase of the measured signal. However, measurement method errors were introduced by the following factors: frequency fluctuation, sampling interval, and integer restriction of the sampling number. The theoretical calculation and experimental results of the signal-to-noise ratio of the proposed measurement method were 2055 and 2403, respectively.

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