Inexpensive LED-based spectrophotometer for analyzing optical coatings

TL;DR

This paper introduces a low-cost, portable LED-based spectrophotometer capable of analyzing optical coatings across a broad spectrum, providing a simple tool for quick identification and characterization of optical elements.

Contribution

The paper presents a novel, inexpensive spectrophotometer design using ten LEDs and automation for optical coating analysis, enhancing accessibility and ease of use.

Findings

Successfully identified different optical coatings

Operates across 365 nm to 1000 nm spectrum

Automated and portable design

Abstract

Optical coatings are widespread in everyday life, from camera lenses to glasses, to complex optics experiments. A simple, reliable device that can quickly and inexpensively analyze optical coatings is a valuable laboratory tool. Such a device can identify unknown or mislabelled optics, and characterize the transmission spectra of optical elements used in an experiment. We present the design and characterization of a LED-based spectrophotometer, and demonstrate its ability to identify different optical coatings. Our approach uses ten LEDs that cover a spectrum from 365 nm to 1000 nm. A small servomotor and microcontroller rotates a LED board to sequentially position each LED over an optical sample, and the transmitted light corresponding to each LED is measured with a silicon photodetector. The device is automated, portable, inexpensive, user-friendly and simple to build.