The Jagged Edge. Glass Fragment Identification. Forensic Materials Science. Scientific Working Group for Materials Science SWGMAT provides Guidelines/Best Practices that have application to Fibers, Glass, Paint, Hair, and Tape.
Glass Fragment Identification
For a given pair of materials,
sine of angle of incidence θ(in material 1)sine of angle of refraction θ(in material 2)
is equal to v1 / v2, and equal to n2/ n1.
The higher the n, the more the light bends
The Becke line is a bright halo near the border of a particle that is immersed in a liquid of a different refractive index.
When the two RI are the same (the match point) the Becke line disappears and minimum contrast between liquid and particle is observed.
Kendall/Hunt Publishing Company
Vehicle Headlight 1.47 – 1.49
Window 1.49 – 1.51
Bottle 1.51 – 1.52
Contact Lens 1.52 – 1.53
Refractive index at 20°C