Cogent Systems Inc. has made its first invasion of a growth market: battlefield technology.

The Pasadena company recently released a rugged, lightweight device that can fit into a standard pocket of military trousers. It’s called the Fusion, and soldiers use it to scan the fingerprints, eye retinas and facial features of terrorism suspects and then transmit the data to a command post.

It’s a change in direction for a company perhaps best known for building fingerprint scanners for noncombat uses. But it meets a need: The wars in Iraq and Afghanistan are forcing soldiers to think more like police officers as they hunt terrorists, said Jeremy Grant, an analyst with Stanford Group Co.

“The feedback we are getting is that even as overall defense spending could decline in some areas, biometrics is going to be an important part of Department of Defense spending going forward,” Grant said. He estimated the military forensics market could be worth up to $100 million.

Cogent engineers got input from special operational forces soldiers who wanted something intuitive to use in a variety of conditions, said Teresa Wu, marketing manager for Cogent. So engineers put a conventional keyboard and 3.5-inch color display on the Fusion. They also made it dust- and waterproof. As waterproof as possible, that is.

“You probably couldn’t throw it into the ocean and expect it to work,” Wu acknowledged.

Wu said Cogent has already received some orders for the Fusion, but declined to name the buyers. The company is also marketing the device to law enforcement. The list price is in the four figures.