Volume 23, Issue 3 (July 1978)
A Rapid, Inexpensive Method of Obtaining Infrared Images
Special photographic techniques have long been used to examine evidence for identification and comparison. Ultraviolet, infrared, and X-ray are the most notable [1,2]. In particular, the visualization of charred writing, obliterated writing, and gunpowder residues and the comparison of inks have been successfully made with the aid of infrared-sensitive films and electronic video techniques . Success with this technique depends on the existence of differences in the tendencies (that is, extinction coefficients) of the components of the materials being studied to absorb radiation in the infrared band. If the ink added to alter a check shows no difference in absorption from the original ink then no distinction between the two can be made with infrared photography.