The University of Auckland

Project #123: A low-cost LED-based spectrometer

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Description:

The reflectance function of an object is a measure of the amount of incident light that is reflected from the surface and is a function of wavelength and position on the surface. The reflectance function is an intrinsic property of an object but is notoriously difficult and expensive to acquire. A recent summer research project has shown that it is possible to use the known spectral shape of multiple light emitting diodes (LEDs) to selectively illuminate a surface and recover the reflectance function using linear algebraic methods from signal processing. Experimental results have indicated that under certain circumstances several hundred samples of the reflectance function can be recovered with as few as 8 LEDs of differing wavelengths. The aim of this project is to design and build a smaller and more compact device that acts as a low-cost spectrometer. It will use the minimum number of LEDs required to reconstruct an approximation of the reflectance function while still being able to usefully discriminate between multiple spectral signatures.

The project will require students with interests in digital signal processing, embedded systems, optics, and have both hardware and software development skills.

Outcome:

The outcomes of the project will be (a) a hardware system that can illuminate a target with known spectral signatures, and record the resulting spectral response, (b) an embedded software system that can perform the appropriate linear algebraic manipulations to infer the reflectance function from the measured samples, and (c) an assessment and critique of the accuracy and success of the system.

Prerequisites

None

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Supervisor

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Lab

Lab allocations have not been finalised