On-chip thin-film filters for multispectral LWIR imaging

This work investigates the integration of LWIR (8-16 µm wavelength) on-chip filters on a microbolometer focal plane with 12 µm pixel size. Several filter types are considered and compared in terms of spectral performance and manufacturing feasibility. We designed and demonstrated experimentally several filter prototypes with excellent agreement between optical simulations and measurements. Next, we investigate the thermography performances (temperature and emissivity measurement) in the case of grey bodies based on the optical performances of the filters. The final discussion outlines the path for improvement of the spectral capabilities of on-chip integrated filters and the perspectives for the development of a multispectral thermal imager with a 4-band Bayer focal plane array.