UNDERSTANDING HANDS:
USING INFRARED LIGHT TO SEE THE VEINS
TEACHER’S PACK
Imaging veins using different types of light.
Each colour of light has a unique wavelength. The veins lie underneath the skin and
sometimes cannot be photographed using a normal camera which uses visible light. This is
because visible light is not strong enough to pass through the skin to reach the veins.
To photograph the veins, Infrared light is shone onto the skin. A light filter is attached to the
camera which only allows Infrared light to pass through. As this filter blocks visible light
from entering the camera, photographs will be in black and white.
Using the images below, try to answer the following questions:
Q1. Infrared (IR) light penetrates the skin more effectively than visible light. What
wavelength is IR light? ___________
Q2. If a filter is applied to the camera to block visible light, what light wavelengths should be
blocked? _______________
Q3. Which image below (image 2 or 3) do you think is the Infrared image?
Q4.Which image below (image 2 or 3) allows more of the Vein Pattern to be seen?
Image 2
Image 3
Comparing Suspect and Offender Images:
In forensic cases it is necessary to compare the vein pattern of an offender with the vein
pattern of a suspect. To compare the vein patterns, the images of the hand are opened in
Adobe Photoshop, and the visible vein pattern is traced. As a simple activity in the class, you
might use an acetate sheet to trace the veins that you see. Once the pattern for each hand has
been traced, these are then compared to see if the patterns match.
Activity 1:
Try tracing the vein
pattern for each image
onto an acetate sheet.
Which image did you
find easier to trace – the
normal light image or
the infrared image?
Webpage:
Email :
www.southampton.ac.uk/theidentitydetectives
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