With infrared light, forensic investigators can tell you whether a document is a forgery or whether paper currency is counterfeit. They can take a paint chip and tell you the make, model, and age of a car. Now the boundaries of infrared forensics are being pushed into uncharted territories by researchers at Lawrence Berkeley National Laboratory, and the results are promising for criminal and antiterrorism investigations, as well as for historians and archaeologists.
http://www2.lbl.gov/Science-Articles/Archive/ALS-IR-Forensics.html