Compact high-speed snapshot multispectral imagers in the VIS/NIR (460-960 nm) and SWIR range (1.1-1.65 nm) and its potential in a diverse range of applications

Abstract

This paper presents the latest advances on Imec snapshot multispectral imagers based on either 3x3, 4x4 and 5x5 mosaic filter patterning on industry ready VIS/NIR and SWIR detectors. The mosaic patterns are implemented by means of high-transmission Fabry-Perot interferometers processed using thin-film technology. Our snapshot multispectral imagers offer a spatial resolution of 640x480 pixels (SWIR) and 2048x1088 (VIS/NIR) down sampled according to the mosaic pattern to acquire data in 9 (3x3), 16 (4x4) of 25 (5x5) spectral bands respectively. To achieve imaging at the native spatial resolution of the sensor, super resolution methods are available post-acquisition. Moreover, our compact USB-3 cameras of 260 gr (SWIR) and 27 gr (VNIR), without lens, reach an acquisition speed of up to 120 multispectral cubes/second and are therefore suitable for dynamic applications, high-speed inspection such as a conveyor belt or UAV inspection. The potential for snapshot cameras in a wide range of applications is showcased in this paper. We first show how applications on industrial quality inspection (chocolate gloss estimation) and precision agriculture (plant disease detection) achieve good discrimination potential in the VNIR range. Specifically, UAV inspection benefits from our compact camera size, low weight, and video capabilities. We then demonstrate the potential for plastic and textile recycling in the SWIR range and the benefit brought by both VNIR and SWIR ranges for people tracking under low visibility conditions. Finally, an application involving the joint use of a microscope and a multispectral camera system is presented for particle contamination exposure assessment. The suitable range is in this case application dependent.