Construction and development of a low-cost hyperspectral imaging system

Sammanfattning: Quantification of spectral data is of great interest in many fields of science, since it can provide further insight into other properties of an object. However, traditional cameras are usually made to image the world in a similar fashion as to how we see it, wherefore they are usually not fit to record nor measure further spectral information. To get a better insight into the spectral properties of an object, a hyperspectral camera might be of use, since those can often identify and measure hundreds of different spectral bands. In this study we look at the construction and further development of an existing design of a push broom hyperspectral imaging system, built with optics for a fraction of the cost of commercial ones. With developed software and objects at hand a spectral calibration was performed, showing a possible spectral range of 184(2)-918(11) nm, but the use of the whole spectral range was however not possible due to limitations in the transmissivity of the lenses below 350 nm. A shift of the spectral range towards longer wavelengths is proposed, which would give further insight into the near infrared spectrum without any information losses. It was found that the spectral calibration of the imager was the main limiting factor of the system, since inaccuracies up to ±11 nm were identified, while the resolution has been found to be 1.4 nm in previous studies, proving that better calibrations are of essence. In good operating conditions, the resolution in the angle of view of the imager was found to be 0.55 mdeg. If the measurement conditions are not as good, or if such kind of spatial resolution is not required, a camera with a smaller detector size and larger pixels could be used to lower the cost of the system without a deterioration in image quality, since the uncertainties in the calibrations and measurement conditions were found to be the limiting factor.