  Infrared (IR) imaging is invaluable across many scientific disciplines, from
material analysis to diagnostic medicine. However, applications are often
limited by detector cost, resolution and sensitivity, noise caused by the
thermal IR background, and the cost, portability and tunability of infrared
sources. Here, we describe a compact, portable, and low-cost system that is
able to image objects at IR wavelengths without an IR source or IR detector.
This imaging with undetected photons (IUP) approach uses quantum interference
and correlations between entangled photon pairs to transfer image information
from the IR to the visible, where it can be detected with a standard silicon
camera. We also demonstrate a rapid analysis approach to acquire both phase and
transmission image information. These developments provide an important step
towards making IUP a commercially viable technique.
