Therefore, a multi-aperture system approach with a specifically adapted microlens array in combination with a slanted, linear variable spectral filter was used. With a size of only 60 x 60 x 28 mm3 and a weight of only 200 g, the compact system offers a large field of view of 68° and a spatial scanning of 400 x 400 pixels per channel. Possible applications of the multi-spectral camera are environmental and agricultural monitoring, industrial production control and sorting as well as biomedical imaging.
A new type of array filter
Furthermore, a new array filter was developed at Fraunhofer IOF. This is a special Fabry-Pérot filter, which is laterally structured by a combination of gray scale lithography and a dry etching process. In combination with an adapted microlens array, another ultra-compact multispectral camera can be realized. This camera has a spatial resolution of 610 x 610 pixels with a field of view of 32°. A reconstruction of the complete multispectral data cube is then performed by superimposing the individual channels based on a spectral calibration of each pixel as well as a spatial calibration of the relative single image coordinates.