  We designed and fabricated a flat multi-level diffractive lens (MDL) that is
achromatic in the SWIR band (875nm to 1675nm). The MDL had a focal length of
25mm, aperture diameter of 8.93mm and thickness of only 2.6um. By pairing the
MDL with a SWIR image sensor, we also characterized its imaging performance in
terms of the point-spread functions, modulation-transfer functions, and still
and video imaging.
