From back in the day when a laser pointer was that big! The device utilized a helium-neon gas laser that had to be externally powered by a battery and power supply hidden in Schwarzenegger's jacket: https://surefire.news/the-terminator-laser-45/
From my observations, laser sights operating at visible wavelengths are not used as frequently these days for military and law enforcement applications, although they are still produced. I tend to see the most about red/green lasers used for short range applications where the deviation between the laser and bullet trajectory will remain small, such as defensive pistol use. To a large extent, visible lasers have been replaced by reflex/red-dot or holographic sights (e.g. AimPoint, EOTech, Trijicon RMR, etc.). Those have various advantages, including usability during daytime, negligible front side signature, no risk of confusing your aiming dot with someone else's when in a group, and choices of reticles.
What is much more prevalent these days is the use of infrared lasers for operations with night vision equipment. NVDs/NODs are usually manually focused and don't have a whole lot of depth-of-field, so you can't employ iron sights on a weapon normally. Various optics (like the reflex and holographic sights mentioned previously) have night vision compatible brightness settings, but the size/length of head mounted NVDs and the limited viewing windows of the sights can make the combination cumbersome. IR lasers are much easier to use, and as long as your adversary doesn't also have night vision equipment, they are fairly covert. Like any other sighting system, the laser has to be correctly zeroed for the expected engagement ranges to get accurate hits. Besides aiming your own weapon, an IR laser pointer can also be used to mark targets or communicate things to friendly units, again with the caveat that it is only covert when the adversary doesn't also have NVDs.
