Specular Reflection
Definition
Mirror-like reflection from a smooth surface where angle of incidence equals angle of reflection; minimised in forensic photography with crossed polarisers to reveal underlying evidence details.
- Field
- Forensic photography, light-matter interaction
- Rule
- Angle of incidence equals angle of reflection
- Occurs on
- Smooth, mirror-like surfaces
- Mitigation technique
- Crossed polarisers
Common questions
Why do forensic photographers use crossed polarising filters?+
One polariser on the light source and another on the camera lens, oriented perpendicular to each other, block the glare of specular reflection while letting diffusely scattered light through, revealing surface detail such as indented writing or fingerprints obscured by glare.
How does specular reflection differ from diffuse reflection in what it reveals?+
Specular reflection bounces light at a single predictable angle and mainly shows surface glare, while diffuse reflection scatters light in many directions and carries the colour and texture information photographers actually want to capture.
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