ArXiv Preprint
A multispectral camera records image data in various wavelengths across the
electromagnetic spectrum to acquire additional information that a conventional
camera fails to capture. With the advent of high-resolution image sensors and
colour filter technologies, multispectral imagers in the visible wavelengths
have become popular with increasing commercial viability in the last decade.
However, multispectral imaging in longwave infrared (LWIR: 8 to 14 microns) is
still an emerging area due to the limited availability of optical materials,
filter technologies, and high-resolution sensors. Images from LWIR
multispectral cameras can capture emission spectra of objects to extract
additional information that a human eye fails to capture and thus have
important applications in precision agriculture, forestry, medicine, and object
identification. In this work, we experimentally demonstrate an LWIR
multispectral image sensor with three wavelength bands using optical elements
made of an aluminum-based plasmonic filter array sandwiched in germanium. To
realize the multispectral sensor, the filter arrays are then integrated into a
3D printed wheel stacked on a low-resolution monochrome thermal sensor. Our
prototype device is calibrated using a blackbody and its thermal output has
been enhanced with computer vision methods. By applying a state-of-the-art deep
learning method, we have also reconstructed multispectral images to a better
spatial resolution. Scientifically, our work demonstrates a versatile spectral
thermography technique for detecting target signatures in the LWIR range and
other advanced spectral analyses.
Noor E Karishma Shaik, Bryce Widdicombe, Dechuan Sun, Sam E John, Dongryeol Ryu, Ampalavanapillai Nirmalathas, Ranjith R Unnithan
2023-03-03
