Active Hyperspectral Sensors at VTT: Combining MEMS-based Fabry-Perot Interferometers and Supercontinuum Lasers for Remote Hyperspectral Measurements
ABSTRACT
Broadband supercontinuum lasers have high intensity and efficiency, and good propagation properties. Thus, they are a promising solution for remote hyperspectral sensing, especially in applications where ambient light is insufficient, such as indoor and underground measurements, or nighttime operation. Furthermore, they can be combined with VTT proprietary MEMS Fabry–Pérot interferometer (FPI) [1] to provide a compact and cost efficient tunable light source. This allows monochrome cameras to be used for active hyperspectral imaging [2], and the approach is also applicable to line cameras [3] and single point scanners [4]. Our active hyperspectral technology has been demonstrated in various applications. For example, in mining [5-7] it can utilized in mineral mapping and ore/waste sorting to improving resource recovery. There is on-going development to cover broader range and longer wavelengths, which would be useful for applications like plastic sorting [7-8]. When the spectral sorting is done at the source, only a small fraction of laser power is emitted at a time. This enables eye-safe operation even at long distances, and is useful in surveillance applications [9-10].
[1] Antila J, et al. "MEMS and piezo actuator-based Fabry-Perot interferometer technologies and applications at VTT." Next-Generation Spectroscopic Technologies III. Vol. 7680. SPIE, 2010.
[2] Kääriäinen T, et al. "Active hyperspectral imager using a tunable supercontinuum light source based on a MEMS Fabry–Perot interferometer." Optics Letters 46.22 (2021): 5533-5536.
[3] Kääriäinen T, et al. “Active hyperspectral pushbroom imager for conveyor belt applications.” Abstract from International Association for Spectral Imaging (IASIM) 2024, p. 124, Bilbao, Spain.
[4] Kääriäinen T, et al. "Active hyperspectral sensor based on MEMS Fabry-Pérot Interferometer." Sensors 19.9 (2019): 2192.
[5] Senna Vieira F, et al. “Active hyperspectral sensor for mineralogy mapping and plastic waste sorting”, in 20th International Conference on Near Infrared Spectroscopy, P-28 (2021).
[6] Dönsberg T, et al. “Supercontinuum laser-based active hyperspectral sensor (AHS) for mining applications”, in Abstract of Optics in Engineering (OIE) 2023, pp. 5-6, 2023.
[7] Senna Vieira F, et al. “Active hyperspectral sensor for mineralogy mapping and plastic waste sorting”, in 20th International Conference on Near Infrared Spectroscopy, P-28 (2021).
[8] Saleh A, et al. "Mid-infrared hyperspectral sensor based on MEMS Fabry-Pérot interferometer for stand-off sensing applications." Scientific Reports 12.1 (2022): 19392.
[9] Kääriäinen T, et al. "Detection and recognition of persons in snowy foliage using active hyperspectral sensing for border control." Infrared Technology and Applications XLVIII. Vol. 12107. SPIE, 2022.
[10] Kääriäinen, T, et al. "Active shortwave infrared pushbroom imager for security and defense applications." Electro-Optical and Infrared Systems XXI. Vol. 13200. SPIE, 2024.
BIOGRAPHY
Timo Dönsberg leads the Optical Spectroscopy group at the VTT Technical Research Centre of Finland. The group specializes in supercontinuum laser-based hyperspectral measurements, utilizing MEMS-based Fabry–Pérot interferometers, and laser spectroscopy for gas isotope sensing. Dönsberg received the M.S. and Ph.D. degrees from the Aalto University, Finland, 2012 in electronics and applications and 2017 in measurement science and technology, respectively. He has over 15 years of experience in spectroscopy, optical metrology and instrument design.