- 01: Introduction
- 02: History
- 03: Propellants, Firearms, and Ammunition Development
- 04: Modern Firearms Manufacture
- 05: Small Arms Ammunition
- 06: Evidence Handling Procedures
- 07: Equipment and Instrumentation
- Introduction
- Objectives
- AFTE Knowledge and Ability Factors
- Measurement, Standards, and Accuracy
- Weight, Force, and Their Measurement
- Dimensional Data and Measurement Tools
- Muzzle Velocity of Bullets
- Stereo and Comparison Microscopes
- Small Tools and Supplies
- Imaging Equipment
- Field Support Equipment
- Computer-Based Technologies
- Firing Facilities
- Selected Bibliography
- 08: Examination of Firearms
- 09: Cartridge and Shotshell Examination
- 10: Characterization and Evaluation of Fired Projectiles
- 11: Bullet Comparison and Identification
- 12: Gunshot Residue and Distance Determination
- 13: Toolmark Identification
- 14: Communicating Results
- Resources
U.S. Department of Justice, Office of Justice ProgramsNational Institute of JusticeThe Research, Development, and Evaluation Agency of the U.S. Department of Justice
Digital Measuring Equipment
Home > Equipment and Instrumentation > Dimensional Data and Measurement Tools > Digital Measuring Equipment
This new generation of comparison microscopes offers two major options for taking and recording measurements:
- Electronic reticules similar to those available for stereo microscopes (see previous page)
- Mouse-driven point-to-point techniques displayed on-screen (proprietary in nature and software dependent)
The accompanying software provides options for saving, storage, and retrieval.
Micrometer
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Micrometers:
Mechanical versus Electronic readouts
The micrometer is a measuring tool frequently used in firearm/toolmark examinations for measuring class characteristics such as thickness, width, or diameter. The device consists of an outer thimble and inner spindle joined by a fine pitch screw mechanism. On older analog or mechanical models, measurements are read with a vernier scale or a mechanical digital readout. The modern micrometer has an electronic display that has nearly replaced the older versions.
Click here to read more about using micrometers in Module 10
The electronic models
- are easy to use,
- are easily zeroed at any point,
- offer a choice of units, usually English and metric,
- are designed for analog use in the event of battery failure,
- are accurate,
- provide easy to read liquid crystal displays (LCD).
Click here to read more about how to use the older analog micrometers.
