Given how complex and vast the station of Talos-I is in Prey, it's easy to miss out on a lot of secrets and amazing loot during your journey. Locked doors and passageways are not just fillers in Prey, but rather there's typically a way around or through if you manage to find a password or a keycard belonging to a door. The rewards could be a new weapon or some much-needed resources.
The Q-Beam is one of the most important weapons in the game, due to its ability to annihilate Weavers, an elusive type of Typhon. While the ammunition for Q-Beam is fairly expensive, it's still a good idea to get your hands on this fantastic futuristic energy weapon as early as possible to maximize your chances of survival. Luckily, even if you missed the first place you could find one, you can still go back or even encounter the Q-Beam in another location. Here's where to find it.
Location One: The Beams And Waves Lab
The easiest and earliest place to get your hands on the Q-Beam is the Beams and Waves Lab located in the Hardware Labs. When you first enter this area, you'll notice the labs are inaccessible due to structural damage. Once Morgan has gained access to the outside of Talos-I, they can make their way over to the labs and fix the breach next to it.
Inside, there's a locked room with a Phantom, which can be ignored for now, since the keycard is only found later on in the G.U.T.S. The actual Q-Beam is in an adjacent room on the right side, propped up on the first table closest to the door. You can use it to kill the Phantom inside the testing chamber as well.
Location Two: Next To Josh Dalton's Body
Finding Josh Dalton's corpse is a side mission you might get if you investigate the terminals inside the Beams and Waves Lab. It turns out Josh Dalton, the original creator of the Q-Beam, had a disagreement with his colleague Lane Carpenter and has met an untimely end. His body can be found floating in the G.U.T.S.
Next to this body, you'll also find another Q-Beam. Make sure to also search Dalton's body for a keycard which will get you access into the closed off section of the Beams and Waves Lab, where a now Typhonized version of Lane Carpenter still walks as a Phantom.
Location Three: The Crew Quarters Freezer
After you've gained access to the Arboretum, the main mission will send you to the Crew Quarters. Head over to the cafeteria, and after dealing with the Telepath and the humans under its control, speak to the man behind the cafeteria counter. Complete his mission, and then return to him, which should gain you access to the freezers of the kitchen.
Inside, there's a ton of loot to be grabbed, including Neuromods and even the Q-Beam. Grab everything you can, because in order to escape you might need to use a Recycling charge to get rid of the ice blocking your path.
Location Four: Cargo Bay B
After your escape from the Crew Quarters and back into the exterior of Talos-I, you'll get a call from the head of security, Sarah Elazar. Your next task is to enter Cargo Bay B and help her and a few other survivors fight off a horde of Typhons keeping them locked in. Entering the Cargo Bay B itself shouldn't be too difficult of a task itself, but beware of the Phantoms roaming around.
Once you've made your way to the survivors, take your time to grab some loot from this area. You should also find a Q-Beam around here, in one of the storage areas on the left side as you first enter the survivors' camp.
Location Five: Mariana Arias' Body
One of the more hidden locations for a Q-Beam and not necessarily worth your time is the body of Mariana Arias. She's located outside the station, nearby the Psychotronics exit. There will be a marker on the body, which can be found easier if you have the Million Dollar Caulk Gun side quest active, since it's nearby.
The body is somewhat concealed, and the Q-Beam is located next to it. There's also a Technopath patrolling in this area, so unless you really need the Q-Beam at this point, this isn't worth your time and effort.