Abstract
The Transverse Field Detector (TFD) is a filter-less and demosaicking-less color sensitive device that easily allows the
design of more than three color acquisition channels at each pixel site. The separation of light into different wavelength
bands is based on the generation of transverse electric fields inside the device depleted region, and exploits the properties
of the Silicon absorption coefficient. In this work we propose such a device for the joint capture of visible and near
infrared (NIR) radiation, for possible applications in videoconferencing and 3D imaging. In these applications the
detector is used in combination with suitably generated NIR structured light. The information of the fourth acquisition
channel, mainly capturing NIR signals, can be used both for sampling NIR light intensity and for subtracting unwanted
NIR crosstalk from visible channels thus avoiding the need for the IR-blocking filter. Together with the presentation of a
4-channel sensor, a suitable algorithm for the processing of signals generated in the visible and infrared bands is
described. The goal of the algorithm is to minimize the crosstalk of NIR radiation inside the visible channels and,
simultaneously, to maintain good color reproduction and noise performance for the sensor, while holding a good
sensitivity of the NIR channel up to 900 nm. The analysis indicates that the algorithm reduces the crosstalk of infrared
signals inside R, G and B channels from 31%, 12% and 5% respectively to less than 2%. Concerning noise propagation,
the worst coefficient of the color conversion matrix (CCM) is -2.1, comparable to those obtained for CCM of Bayer
Color Filter Arrays.
