UV–Vis Spectrometers
Spectrophotometry: Introduction
IR Spectrometers
Raman Spectroscopy Instrumentation: Overview
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Updated: Mar 29, 2026

Subjective Refraction Test Using a Smartphone for Vision Screening
Published on: October 18, 2024
Chenji Zhang1, Gong Cheng2, Perry Edwards1
1Department of Electrical Engineering, The Pennsylvania State University, University Park, Pennsylvania 16802, USA. ZLiu@engr.psu.edu.
We developed a smartphone spectrometer for measuring protein concentration. This portable device uses a G-Fresnel lens for nanometer resolution in the visible spectrum, enabling easy quantification via Bradford assay.
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