1. Forensic Microscopy
Microscope 1

2. Forensic Microscopy
Generally takes one of six forms depending on the type of evidence to be examined
Compound microscope
Stereoscopic microscope
Comparison microscope
Polarizing microscope
Microspectrophotometer
Electron microscope

3. Compound Microscopes The “classic” microscope
Light is passed through object from beneath
Image is upside down and backwards
May possess a zoom magnification or multiple lenses of varying strength
Monocular and binocular versions
Generally up to 1000x magnification
Higher magnification limitations
“Depth of focus” is decreased and creates focusing challenge
Cuts down on available light

4. Compound Microscopes Major Components Eyepiece Tube Nosepiece
Objectives
Stage
Focus
Arm
Base

5. Compound Microscopes

6. Comparison Microscopes
Essentially two compound or stereographic microscopes joined by a “bridge”
Vital for side by side comparison of two pieces of evidence
View can show either microscope or can be “split” to show both at the same time
Especially useful in ballistics and hair/fiber cases

7. Comparison Microscopes

8. Stereographic Microscopes
Most frequently used type of microscope in forensics
Light is passed either through an object or from above
Image is projected right side up and correct right to left
Usually the only method for opaque forms of evidence
Especially useful for soil analysis, entomology and macroscopic evidence
Magnification generally ranges from 2x to 125x
Often called “dissecting” microscopes

9. Stereographic Microscopes

10. Polarizing Microscopes
A special microscope application that outfits a “normal” microscope with two devices (a polarizer and an analyzer)
The polarizer is used to impact incoming light waves to reveal special properties of a material
Affected light waves then pass through analyzer before hitting the eye
Especially useful in soil analysis (minerals) and the identification of artificial fibers

11. Polarizing Microscopes

12. Polarizing Microscopes
Blemish on an LCD screen visible in polarized light (right) but not in normal visible light (left)
Polarizing microscope view a a thin slice of granite

13. Electron Microscope
Unique in that it uses a beam of electrons aimed at the object
Does not use light
Extremely high magnification possible
Ranging from 10x – 100,000x
Can also be used as a spectroscope in some applications
Useful in gunshot residue cases
Very expensive

14. Electron Microscope

15. Electron Microscope

16. Electron microscope

17. Electron microscope

18. Microspectrophotometer
A beam of light is aimed at the object and its spectrum can be collected
The specific spectrum will be unique to particular chemicals, fibers, etc.
Spectral “fingerprints” can then be used to determine specific matches between different evidence samples

19. Microspectrophotometer

20. Microspectrophotometer