While most of the imagers available today use the Bayer mosaic to allow color images to be captured, some sensor and camera manufacturers now offer custom filters that can be added to sensors and cameras to target specific application areas.

http://www.vision-systems.com/articles/print/volume-20/issue-7/departments/technology-trends/filters-and-optics-multispectral-filters-let-camera-vendors-target-niche-markets.html