If that's the case, I think that you're making the rotation right (there's nothing wrong with the code you posted), but you're drawing the laser wrong. You might want to translate the image so that the center of the origin side is at (originX,originY) position.
If I understand you correctly, I should set originY to the laser height / 2?
Also, I think you might want to point to the center of the meat boy instead of the corner, it makes things easier. Well, generally, it makes it easier to work with the center of things, and even more when rotations are involved.