360 likes | 1.03k Views
Forensic Examination of Glass. Goals in examining glass evidence:Determine the types of glass at the sceneDetermine how the glass was fracturedUse physical characteristics to classify itIndividualize the glass to a sourceCompare physical and chemical characteristics:Optical properties: color and refractive indexNon-optical properties: surface wear, striations from manufacturing, thickness, surface film or dirt, hardness, densityChemical properties: additives or trace elements.
E N D
2. Forensic Examination of Glass
3. What is Glass?
4. What Types of Glass Are There?
5. What Types of Glass Are There?
6. How Do Glass Windows Break?
7. How Does Glass Break?
8. How Does Glass Break?
9. Exceptions to the Three R Rule
10. Types of Fractures by Projectiles
11. Which side was the bullet fired from?
12. Which Bullet Hole Was First?
13. Putting it Back Together Again?
14. Learning Check
15. Glass Transfer Evidence
16. Collection of Glass Samples
17. Forensic Examination of Glass
18. Optical Properties of Glass
19. Nonoptical Physical Properties of Glass
22. Why Measure Density? Can be used as a screening technique with large numbers of fragments.
Useful in identifying multiple sources present in the known and/or questioned samples.
It is nondestructive and an intensive property (not dependant on sample mass).
Need to measure very precisely in parts per hundred or thousand or better.
23. Glass Density
24. Density by the Flotation Method
25. Why Measure Refractive Index?
26. Snell’s Law
28. Refractive Index By Immersion
33. Chemical Analysis of Glass
34. Learning Check
36. The Wave of the Future: Laser Ablation