Class 2 St Microscopy Fall 2024 copy

Trace Evidence

Small pieces of material, man-made or naturally occurring, often microscopic, that can be transferred during a crime.

Locard's Exchange Principle

The theory that states 'Every Contact Leaves a Trace', meaning that there is always a transfer of material when objects come into contact.

Persistence

The duration that transferred evidence remains in a location before it's further transferred, degraded, decomposed, or collected.

Microscopy Lab

A practical session where students examine small items of evidence under a microscope to analyze trace materials.

Polarized Light Microscopy

A microscopy technique used to analyze materials by observing their light interaction with polarized light.

Primary Transfer

Evidence directly transferred from the source to the target.

Secondary Transfer

Evidence transferred from one person or object to another before reaching the final target.

Microscopic Evidence

Evidence that is too small to be seen with the naked eye and requires a microscope for examination.

Non-contact Transfer

Transfer of trace evidence without physical contact, often through airborne particles.

Collection Methods

Techniques used to collect trace evidence, including picking, scraping, tapping, and vacuuming.

Ocular Micrometer

A scale inside the eyepiece of a microscope used for measuring the size of specimens.

Calibration of Micrometer

The process of determining the accuracy of the ocular scale with reference to a stage micrometer.

Microscopic Analysis

Examination of small particles using a microscope to provide forensic evidence in investigations.

Field of View

The extent of the observable area through the microscope, which decreases with higher magnification.

Resolution

The smallest distance between two points at which they can still be distinguished as separate entities.

Stereomicroscope

A type of microscope used mainly for examining larger objects with lower magnification.

Comparison Microscope

A microscope that allows for side-by-side comparison of two samples.

Low Power Microscope

A type of microscope used to examine larger objects with lower magnification.

High Power Microscope

A microscope that offers high magnification to inspect small specimens like fibers and hair.

Chemicals for Evidence Collection

Specific substances used during the evidence collection process to avoid contamination and degradation.

Factors Affecting Transfer

Elements that influence how trace evidence is transferred, such as surface nature, contact force, and environmental conditions.

Evidence Contamination

Undesired mixing or mingling of evidence that can compromise its integrity.

Microscopy Theory

The principles and techniques regarding the use of microscopes in forensic analysis.

Magnification

Increasing the apparent size of an object through lenses to facilitate detailed examination.

Types of Microscopes

Different varieties of microscopes including simple, compound, stereomicroscopes, and electron microscopes.