Infrared multispectral imaging with silicon-based multiband pass filter and infrared focal plane array

Abstract

This paper reports the implementation of a siliconbased infrared (IR) multiband pass filter (BPF) on an uncooled microbolometer IR focal plane array (IR-FPA), both of which are fabricated by the standard CMOS process. IR spectroscopy has been widely used as a sample identification technique, exploiting the fact that each molecule structure has a unique spectral feature. Using IR-BPF and IR-FPA, a low-cost and compact IRspectral imaging system is realized. The microbolometer IR-FPA exhibits broad spectral response sufficient to cover the IR-region from the mid-infrared (3 µm) to far-infrared (8 µm~), which is broader than the coverage of conventional non-silicon-based photodetectors such as mercury cadmium telluride. Single-band images of invisible gases such as ethanol vapor and CO 2 in breath are obtained with the IR-FPA. For multiband imaging, a guidedmode resonance IR filter is fabricated by patterning aluminum (Al) layer of 100 nm thickness on a silicon-on-insulator wafer.

MIR spectral characterization of plastic to enable discrimination in an industrial recycling context: II. Specific case of polyolefins

“…However, HSI cameras operating in MIR do not currently cover the full range but only MWIR, Middle Wavelength Infrared (2-5 µm, 5000-2000 cm À1 ), or LWIR, Long Wavelength Infrared (7.4-14.0 µm, 1350-700 cm À1 ), even if the limits given here are subjects to variations. Scientific literature about extending MWIR photosensors limits, not necessary about HSI application, is pretty rich nowadays (Delmas et al, 2017;Serincan et al, 2018;Ueno et al, 2015), demonstrating that these limits could change in the future. A few papers also focused on its application to plastics identification.…”