Forensic dental photography 219the use of CDs or DVDs, or even an Internet off-site data storage vender,
if legally allowable.
The frequency of the backups and the suggestion to use multiple backup
media cannot be emphasized enough. There will be an event in the digital
photographer’s lifetime when there will be a catastrophic loss of digital data
via hard disk crash, electrical power surge during a storm, water or dust con-
tamination, or some other incident. The only protection of the existing data
is multiple frequent backups. While some have advocated doing backups on
CDs or DVDs, it is important to understand that the surface integrity of the
CD or DVD can environmentally degrade over time, rendering the data on
the disks worthless. As part of the standard technique, the digital photogra-
pher must include routines for multiple frequent backups of the data files.
11.9 Alternate Light Imaging and
Fluorescent Imaging TechniquesThe field of forensic investigation has seen a tremendous growth in the utili-
zation of alternate light imaging for both locating and photographing latent
evidence. Fingerprints,7, 8 serological fluids left behind at a crime scene (blood,
semen, saliva),^9 types of ink used to counterfeit or falsify documents,^10 and
bruises or other pattern injuries left on human skin sustained during violent
crimes can not only be more easily detected but also transformed into excit-
ing and important exhibits with the utilization of fluorescence.^11 The applica-
tion of this new technique has numerous titles. For simplicity, in this chapter,
it will be referred to as alternate light imaging (ALI). The technique of photo-
graphing evidence with alternate light is called fluorescent photography.
“Fluorescence is the stimulation and emission of radiation from a subject by
the impact of higher energy radiation upon it. Luminescence is a general term
for the emission of radiation that incorporates fluorescence and phosphores-
cence, as well as other electro-chemical phenomena like bioluminescence.”^12
All of the physical reactions that occur during illumination with full-
spectrum visible light (reflection, absorption, transmission, and fluorescence)
also occur for monochromatic light. Monochromatic light refers to the pro-
duction of a single wavelength of light. Almost any object can be made to
fluoresce, depending on the wavelength of light radiated upon it.^13 Although
this filtered light is sometimes as much as 30 nm in width, it is called mono-
chromatic (a misnomer) because very bright full-spectrum light is filtered to
only allow one color of visible light to be predominant. This is accomplished
with the use of bandpass filters, which are placed in the path of the light
usually on the front of the lens.