A simple and inexpensive imaging device is described adaptable to ir, microwave, or ultrasound radiation. An image is projected on a heat-sensitive surface which expands in proportion to the intensity of the radiation. The resulting bas-relief is recorded by double exposure holography.
J. G. Hirschberg, "A Novel Means of Thermal Imaging," Appl. Opt. 9, 761-763 (1970)