How Does IFM Work?
Discover how IFM is applied to modern day forensics as a tool for criminal intelligence for identification of firearms
How it Works
The codes placed intentionally onto a firearm’s firing pin or breech are linked to the serial number of the gun. These codes are formed as micro embossing structures, which come into contact with the cartridge when it is ejected from its chamber. There are two codes imprinted onto the firing mechanism. The first is a combination of serialized codes while the second is a gear code that wraps around them.
Micron level features are optimized to the multivariate and dynamic behavior of the firearm mechanism being outfitted. Through a highly evolved and refined protocol, a firearm model is used to test intentional stamping geometries, including draft angle, character height, separation, surface finish, width, depth, as well as the physical arrangement of the imprint within the firearm for optimum durability and transfer ability allowing for enhanced optical character recognition, with microstamped cartridges, specific font structures are created.
This optimization routine allows for a higher level of transfer in comparison to unintentional microstamping. Even if the code is somewhat skewed while stamped onto a cartridge, the use of heuristic algorithm code extraction enables the ability to read the unique numbers to track the firearms. This can be pictured below.
The Power of Heuristics
Close up of micro- stamp imprint on cartridge
Zoomed out micro- stamp imprint on cartridge
Heuristic algorithm code extraction example.
Heuristics algorithm explains how, even when a code is skewed, our brains are still able to process the letters and numbers
Technology Used to Extract IFM Codes from Cartridges
The optical microscope also referred to as a light microscope, is a type of microscope that commonly uses visible light and a system of lenses to generate magnified images of small objects. Optical microscopes are the oldest design of microscope and were possibly invented in their present compound form in the 17th century. Basic optical microscopes can be very simple, although many complex designs aim to improve resolution and sample contrast.
TACLABS™ utilizes polarized light in a polarizer analyzer configuration to enhance the contrast of the micro stamp.
The Olympus DSX1000 is the newest high resolution microscope that allows us to examine and document high quality imagery of laser imprinted firing pins and microstamped cartridges.
TACLABS™ is able to utilize this tool for both high precision measurement and analysis to continue to develop intentional microstamping methods.
Polarizer / Analyzer Metallographic Microscopy
TACLABS™ over the years has adapted methods to enhance IFM features by leveraging a microscopy technique termed a Polarizer / Analyzer Configuration. With Stereo Microscopy and even traditional tool scopes, the White Light source is polarized illuminating the raised metal that forms the IFM coded features. The reflected polarized light is then imaged through an analyzer, which takes the form of another polarizer, through the imaging lens of the microscope, which enhances the edges of the features and reduces the glare on the flat surfaces. By rotating the analyzer or the polarizer on the illuminator, the features can be further enhanced. Below is an example of this technique.
A scanning electron microscope (SEM) is a type of electron microscope that produces images of a sample by scanning the surface with a focused beam of electrons. The electrons interact with atoms in the sample, producing various signals that contain information about the surface topography and composition of the sample. The electron beam is scanned in a raster scan pattern, and the position of the beam is combined with the intensity of the detected signal to produce an image.
TACLABS™ utilizes both standard and back scatter SEM imaging methods in its analysis of multiple pin strike cartridges.