Accurate laser-based characterization of liquid refractive index for advanced undergraduate laboratories

This paper presents a compact, low-cost optical setup designed for measuring refractive indices of liquid samples. The system employs a tilted transparent quartz cuvette placed on a rotating stage, where a small angular offset between the laser beam and the cuvette induces a lateral displacement of...

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Bibliographic Details
Main Authors: Wang, Zhe (Author) , Barwig, Chantal (Author) , Dave, Gaurav (Author) , Selhuber-Unkel, Christine (Author)
Format: Article (Journal)
Language:English
Published: April 2026
In: American journal of physics
Year: 2026, Volume: 94, Issue: 4, Pages: 331-336
ISSN:1943-2909
DOI:10.1119/5.0297246
Online Access:Verlag, kostenfrei, Volltext: https://doi.org/10.1119/5.0297246
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Author Notes:Zhe Wang, Chantal Barwig, Gaurav Dave, and Christine Selhuber-Unkel
Description
Summary:This paper presents a compact, low-cost optical setup designed for measuring refractive indices of liquid samples. The system employs a tilted transparent quartz cuvette placed on a rotating stage, where a small angular offset between the laser beam and the cuvette induces a lateral displacement of the transmitted beam. By quantifying this displacement, the refractive index of liquids (water and 1-propanol in this paper) is determined with minimal optical complexity. The laser beam displacement is accurately quantified by the knife-edge technique. Key physical quantities, including beam displacement and refractive index, are derived through an optical ray transfer matrix. Students typically obtain accuracy of three significant figures after the decimal point. Experimental results demonstrate agreement with theoretical models, validating the method's precision for applications in materials science, biochemical sensing, or quality control. Considering the simplicity, affordability, and versatility of this device, the setup integrates practical optical experiments with fundamental optical principles, making it well-suited for both research and educational environments.
Item Description:Veröffentlicht: 1. April 2026
Gesehen am 23.04.2026
Physical Description:Online Resource
ISSN:1943-2909
DOI:10.1119/5.0297246