Thermochromic materials for infrared recording

For the purpose of recording coherent infrared signals, a material is needed which is properly sensitive and which has the necessary resolution. The red thermochromic compound cuprous mercuric iodide (Cu2HgI⁴) has these attributes. Using a paint made with Cu2HgI⁴and a silicon varnish, an infrared hologram has been recorded with a CO2laser at 10.6 µm. The hologram was photographically reduced in size and was reconstructed in the visible.