E. E. Smith - Lensman - Book 3 - Galactic Patrol

The Galactic Patrol has been given the ultimate weapon in its war against the evil pirate Boskone: The Lens. But even though the Patrol's Lensmen are the most feared peacekeepers in the galaxy, they aren't quite sure how to use their unique gift. Things are about to change, however. Kimball Kinnison has just graduated from the academy, and now that's he's earned his Lens, he's determined to figure out how it works. Kinnison begins his journey of discovery by taking command of the Brittania, an experimental ship that's as likely to kill him as it is the Boskone raiders it was built to fight. That leads him on a series of whirlwind adventures that include a visit to the planet Arisia--where the mysterious creators of the Lens make their home--and end up in a confrontation with Helmuth, who may well be Boskone himself.