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Publication: Michael Noel Lab

April 10, 2024

Using Lock-In Detection to Build a Barcode Scanner

Authors: Riley E. Alexander '23, Maya M. DiFrischia '23, Margaret J. Doubman (HC), Stefany Fabian Dubon '23, Lily Goltz '23, Yuqian Li '23, Rebecca A. Long '22, Genevieve Love '22, Nina Martinez Diers '24, Matangi Melpakkam '23, Catie Robinson '23, Elizabeth M. Tompkins '23, Avalon L. B. Vanis '23, Xinrui Wang '24, Mallory Yu '22, Sarah E. Spielman (Ph.D. candidate), Michael W. Noel

Source: American Journal of Physics, Volume: 91, Issue: 12, Pages: 1023-1030, DOI: 10.1119/5.0151621, Dec. 2023

Type of Publication: Article

Abstract: Lock-in detection is a widely used experimental technique in which a weak signal is measured by modulating it at a particular frequency. Then, by detecting an experimental output at that frequency, the desired signal can be isolated from much larger-amplitude noise. Here, we report on the implementation and optimization of a homemade laser barcode scanner based on the lock-in technique. Our setup is comprised of components that are readily available in an undergraduate instructional laboratory. The successful transcription of the barcode into a digital signal was achieved, and this digital signal was collected with a simple computer and processed to reveal the encoded number.