Abstract: An infrared imaging system is described which includes a pyro-optic sensor for receiving a thermal image on one of its sides, the sensor exhibiting a substantial change in refractive index in responses to changes in its temperature. A light beam is projected onto a second side of the sensor, the beam being selectively, locally reflected by the sensor in accordance with local changes in its refractive index. A receiver detects the reflected beam and responds to the reflectance changes to derive a visible image of the thermal image.The pyro-optic sensor comprises a sandwich structure which includes a film of energy absorbant material upon which the thermal image is received; a thin film of thermal-optic material; and a supporting layer which includes an optically transparent foam positioned next to the pyro-optic material on the side at which is directed an interrogating light beam.