Answer 1:
To get a background on this topic, please click
here and read the text below Another
way to detect fingerprints is vacuum metal
deposition. In this process, the surface in
question is placed in a vacuum chamber which is
pumped down to a very low pressure. Then a thin
layer of gold is deposited onto the surface,
followed by the deposition of a thin layer of
zinc. The zinc layer attaches to the gold in the
area where there is no fingerprint. This creates
contrast between the valleys and ridges of the
print. Vacuum metal deposition works well only on
smooth surfaces that are small enough to fit in
an
evaporation chamber; however it works very well
in
these cases and is becoming a popular means of
latent fingerprint detection. Many other
methods also exist such as the use of argon
lasers
or infra-red spectroscopy.
References:
http://www.scafo.org/library/11
0502.html
(Southern California Association of Fingerprint
Officers)
http://www.rcmp-grc.gc.ca/fsis-
ssji/firs-srij/bulletins/vacuum-vide-eng.htm
(Royal Canadian Mounted
Police)
http://en.wikipedia.org/wiki/Fingerprint#Late
nt_fingerprint_detection | 
