Forget about laser light, that is visually detectable.
Infrared laser light is invisible to the human eye but cameras can "see" near-infrared that's pointed directly at the lens. You can test this with any remote control. However, you won't see or detect a laser beam that's not aimed at you. All you'll detect is faint scatter from the air/vapor that it passes through.
Of course, extremely powerful beams ionise the air molecules so you'll see the glow. However, you might miss a brief pulse.
Infrared laser light is invisible to the human eye but cameras can "see" near-infrared that's pointed directly at the lens. You can test this with any remote control. However, you won't see or detect a laser beam that's not aimed at you. All you'll detect is faint scatter from the air/vapor that it passes through.
Of course, extremely powerful beams ionise the air molecules so you'll see the glow. However, you might miss a brief pulse.