  Multi-spectral imagers reveal information unperceivable to humans and
conventional cameras. Here, we demonstrate a compact single-shot multi-spectral
video-imaging camera by placing a micro-structured diffractive filter in close
proximity to the image sensor. The diffractive filter converts spectral
information to a spatial code on the sensor pixels. Following a calibration
step, this code can be inverted via regularization-based linear algebra, to
compute the multi-spectral image. We experimentally demonstrated spectral
resolution of 9.6nm within the visible band (430nm to 718nm). We further show
that the spatial resolution is enhanced by over 30% compared to the case
without the diffractive filter. We also demonstrate Vis-IR imaging with the
same sensor. Furthermore, our camera is able to computationally trade-off
spectral resolution against the field of view in software without any change in
hardware as long as sufficient sensor pixels are utilized for information
encoding. Since no absorptive color filters are utilized, sensitivity is
preserved as well. Finally, the diffractive filters can be easily manufactured
using optical lithography and replication techniques.
