Forensic Infrared and Full Spectrum Photography
With digital infrared and full spectrum, forensic photography is much easier. Full spectrum cameras can take UV, visible light, or IR pictures with just a change of a filter in the front, which is much more convenient than having to change between specialty film.
Many of these cameras have telephoto lenses as well as a live view which is very usefull for forensics. Without liveview, you must take many test pictures effectively blind to UV or IR light. With live view, you can view directly in infrared on the LCD.
US currency has banding patterns that are visible in the IR spectrum, allowing counterfeits to be easily spotted. You can see below some of the banding patterns.
Infrared photography can be used in document recovery. Many inks and stains appear clear when viewed in infrared, allowing you to see underneath stains to the original document.
Below, text written over by an imitation sharpie felt pen, the text below is not visible.
In the next picture, viewed with an infrared camera, you can clearly see the text below the ink.
This effect can not only be used to see below inks, but it can be used for a quick test of wether or not a document has had a single ink used on it. Because only some inks are transparent, if someone made an addition to a check, for example, under an IR camera it will immediately stand out.
Just like the inks above, many other colorings look different in visible and white light. Many colors that look the same to the eye have different infrared properties. This can be used to spot if a different kind of paint or ink was used, for example if someone repainted a portion of a wall, the new and old paint can look very different. This can be a useful tool for insurance investigations.
Another use is to spot some forms of fraud.
Below, the check does not look suspicious, all the writing looks like it came from the same pen.
However, when viewed with an IR camera, you can see that the some of the inks came from a different pen.
Many natural dies will show up differently as well. While synthetic greens may show up dark in infrared, the chlorophyll in leaves comes out white. Many fibers have unique IR or UV charecteristics allowing for easy identification between types of fiber.
The UV range has its own wide range of capabilities as well. Many stains will apear clearly under UV light conditions.
When viewed with a UV sensative camera, skin bruising will become more apparent.
In either UV or IR, small blood stains will be more visible, particularly against a dark background. Bullet residue can also become much clearer.