Spectr@phone

Development of a hand-held multi-functional multispectral imaging device

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Objective

The aim of this research project is to develop and test a low-cost hand-held multi-functional multispectral imaging device for the age determination of bruises. The TUD focus lies on the development of a large mirror Fabry-Pérot interferometer operated with nanometer precision and the choice of a clever optical design.

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Impact

Child abuse is a widespread problem, but very often detecting it, proves to be very difficult. The goal of this project is to develop a spectral imaging system that can determine the precise age of a bruise. With this additional information, it is possible for a doctor to base his judgement about whether a child was abused on more than just a suspicion.

Spectral imaging, which means taking an image with the full spectral information in each pixel, has the potential to measure the age of a bruise. The spectral information obtained by imaging skin gives insights into the chemical composition of the upper skin layers. So the technique has been applied in plenty of cases, i.e. to determine the oxygen content of blood, or to find malignant tumours. In the case of bruise imaging the areas, where different chromophores (haemoglobin, bilirubin) can be found in the skin, are analysed to calculate the exact age of the bruise.

Current technology can provide hyperspectral cameras, that are capable of measuring bruises, but they are in fact only available for large hospitals who can afford buying a camera for more than €30000.

The goal of this project was developing a small cheap alternative for powerful spectral skin analysis. To achieve this the Academic Medical Center (Amsterdam) joined forces with the Saxion University of Technology, Avantes BV, Anteryon BV and the TU Delft to create a new camera based on modern wafer optics manufacturing techniques. While Richelle Hoveling and Maurice Aalders at the AMC focus on the development of the age determination algorithm, Saxion takes care of packaging and presentation of the product in several student projects. Anteryon and Matthias Strauch at TU Delft focus on the development of a Fabry-Pérot optomechanical spectral filter with nanometer precision. Avantes is responsible for electronics and system integration.

During the project several technical issues had to be investigated like the exact control of the surface roughness of the Fabry-Pérot mirrors, the design of the mirror coatings and the choice of an appropriate optical system.

The analysis of different lens systems in combination with the Fabry-Pérot interferometer gave insights into new system design criteria that are published in http://www.jeos.org/index.php/jeos_rp/article/view/15037.

Matthias Strauch, Irina L. Livshits, Florian Bociort, and H. Paul Urbach, Wide-angle spectral imaging using a Fabry-Pérot interferometer, Journal of the European Optical Society: Rapid Publications, 10, 2017, doi:10.2971/jeos.2015.15037

The research has been finished successfully and a spectral camera prototype has been developed.

The Fabry-Pérot interferometer is now available comercially.

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Publications

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