Spectral characterization of a hyperspectral imaging system using optical standards

Hyperspectral imaging relies on the optical properties of materials which absorb or scatter light at different wavelengths. To obtain repeatable results from a hyperspectral or any other imaging system, the system´s spectral response must be characterized using optical standards against the light source used. Light sources vary in their spectral properties and their performance over time. Differences in light sources, such as intensity or emitted wavelengths, can affect the acquired data; however, through calibration and data normalization, such effects can be minimized. Knowing the imager´s spectral response to the light source is vital for analyzing hyperspectral data and interpreting the results from the media of interest. In this study, the spectral response of the hyperspectral imaging system to tungsten halogen diffuse light source is determined in reflection and transmission modes using optical standards of varying thickness. In addition, the system´s response to the same light source over time is investigated. The noise levels in single and averaged spectra are measured and reported. System normalization methods are described. For the tested hyperspectral imaging system and light source, the noise reduces in averaged spectra across multiple spectra compared to single spectra. Spectral peak shifts have also been observed at different light source power levels.