Quick medical question

Short answer-no. A contusion is a bruise. Lasers are focused light. Light will not bruise you.
You may be thinking of a concussion, which is what happens to your brain after a blow to the head.
That said, light CAN hurt you. Lasers can burn you or blind you. Other types of focused radiation beams can damage brain tissue or cause cancer (wiki gamma knife radiotherapy for example). So you could permanently damage someone's brain that way. For a physical brain injury, you just can't beat a good hard crack on the noggin, though.

Unless someone hits you over the head with the thing. I remember back in the eighties, the shop at school had one, it was the size of a lunchbox. This was before laser pointers. (though, occasionally, someone would try to point with it) That thing could cause some damage.

Sarpedon said:

Unless someone hits you over the head with the thing. I remember back in the eighties, the shop at school had one, it was the size of a lunchbox.

Click to expand...

Awwww, Sarpedon, I was about to write "Sure. Hit the character on the head with the machine " Guess I lost the oportunity of the joke

Like others have said, the short answer is no. However, depending upon the type of laser used there are varrying depths of tissue coagulation deep to the area burned. If that depth is relatively shallow about 12-24 hours after the burn as the white blood cells etc try to clean up the area, there can be a secondary or delayed bleed. This was common in the early days of laser prostatectomies where everything looked dry (nothing bleeding) at the end of the surgery and then later that night the patient would suddenly go into clot retention. Although this process is actually a hematoma rather than a bruise, it might be what you are getting at in your question.