Visualization of superficial vasculature using a Vidicon camera tube with silicon target.

Infrared photography has been used by a number of authors in the study of disease (Ronchese, 1937; Massopust, 1948). The technique depends upon the fact that radiation of wavelength 0.7 to 1.2 μm penetrates the skin to a depth of about 2 mm and is absorbed more strongly by blood than surrounding tissues. To avoid shadows, the area to be photographed should be illuminated with diffuse uniform lighting and, since infrared emulsions are sensitive to visible as well as infrared radiation, a filter must be placed over the photographic camera lens. Although infrared photography is in principle a simple technique, it requires careful execution to achieve consistent results.