Laser codes trace bullets back to guns

18 Oct 2002

Tracing a bullet back to a specific firearm could be aided by an embossing system being patented by a US company.

US-based NanoVia is patenting a laser-machined stamp that embosses a unique code on the casing of a bullet as it is fired from a rifle or handgun. The technique could become a valuable forensic tool during a criminal investigation.

Marked casing

Current techniques rely on linking specific scratches and marks on the casing of bullets back to firearms. According to NanoVia's vice president of R&D Todd Lizotte, its approach is different as it embosses an alphanumeric code or a 2D barcode. "Because each firearm stamps the cartridge casing with the serial number of the firearm, there is a direct code that links the casing to the firearm," he said.

The company is currently investigating the optimum position for the stamp inside the firearm. "We want to find places within standard handguns where the technology cannot easily be defeated by criminals," explained Lizotte. To date, NanoVia has looked at writing codes on the firing pin and the barrel area of a handgun.

NanoVia uses a diode-pumped solid-state laser emitting at 266 and 355 nm to write the stamp. Lizotte says that the company's optical system uses holographic imaging techniques that can form precise codes, which can be customized during the marking process.

This results in a pattern containing characters that are 7 to 15 microns tall in the form of an alpha numeric or a 2D barcode. "We have developed a proprietary aspect ratio that ensures mechanical strength and a quality embossed image," Lizotte told Optics.org.

He explains that when the gun is fired, the bullet is placed under extreme pressure as it is shot down the barrel. As a result, the brass cartridge casing is forced against the stamp for a few milliseconds and receives a permanent mark, before being discarded from the gun. The embossing goes a few microns into the casing surface, just enough to be detected by a machine vision system that the company is also developing.

"My feeling is that a combination of technologies will implemented over the next few years and ours will be one of many to help law enforcement," said Lizotte. "There are a great number of experts within this field. We will look to provide possible solutions and let them guide us on how to implement it effectively and efficiently."

Author
Jacqueline Hewett is news reporter on Optics.org and Opto & Laser Europe magazine.