Comparison Microscopy
Definition
A technique in which known and questioned samples are viewed simultaneously through split or adjacent fields in a single instrument. Used in toolmark, hair, fibre, and firearms examination to assess class and individual features side by side.
- Instrument
- Comparison microscope with split or bridged optical field
- Used in
- Toolmark, hair, fibre, firearms examination
- Compares
- Class and individual characteristics side by side
- Advantage
- Simultaneous viewing avoids memory-dependent comparison
Common questions
Why is simultaneous viewing preferred over comparing separate photographs?+
Viewing known and questioned samples side by side in the same optical field at the same time and magnification removes the need to rely on memory or on photographs taken under different lighting and orientation, which reduces a source of comparison error.
What distinguishes a comparison microscope from an ordinary compound microscope?+
A comparison microscope links two separate optical paths through a bridge so that two physically separate specimens appear together in a single split field, whereas a standard compound microscope only presents one specimen at a time under one objective.
Related terms
- Acquired Characteristics
- Individual characteristics that develop after manufacture through use, wear, damage, or corrosion. A new shoe has only class characteristics; a worn shoe...
- Class Characteristics
- Features deliberately or systematically imparted to a group of items by design or manufacture, such as the calibre of a bullet, the...
- Elimination Sample
- A known reference sample collected from someone who had legitimate access to a scene or item, used to separate their class and...
- Individual Characteristics
- Surface features on a fired bullet or cartridge case that arise from random or unique events (tool wear, corrosion, service damage) and...
- Source Attribution
- The inferential step of linking a trace to its donor. Serology identifies blood as human and potentially as a specific genetic type;...