A compact snapshot multispectral imager with a monolithically integrated per-pixel filter mosaic

The adoption of spectral imaging by industry has so far been limited due to the lack of high speed, low cost and compact spectral cameras. Moreover most state-of-the-art spectral cameras utilize some form of spatial or spectral scanning during acquisition, making them ill-suited for analyzing dynamic scenes containing movement. This paper introduces a novel snapshot multispectral imager concept based on optical filters monolithically integrated on top of a standard CMOS image sensor. It overcomes the problems mentioned for scanning applications by snapshot acquisition, where an entire multispectral data cube is sensed at one discrete point in time. This is enabled by depositing interference filters per pixel directly on a CMOS image sensor, extending the traditional Bayer color imaging concept to multi- or hyperspectral imaging without a need for dedicated fore-optics. The monolithic deposition leads to a high degree of design flexibility. This enables systems ranging from application-specific, high spatial resolution cameras with 1 to 4 spectral filters, to hyperspectral snapshot cameras at medium spatial resolutions and filters laid out in cells of 4x4 to 6x6 or more. Through the use of monolithically integrated optical filters it further retains the qualities of compactness, low cost and high acquisition speed, differentiating it from other snapshot spectral cameras.