Then add in a RGB curves node to set the color of your laser. Now what you wan to do is using add nodes add them all together. connect your vector blur to all of these. Now add in four blur nodes set to fast guassian. Do not do any thing with the alpha node connect. Connect speed with speed, z to z, and image to image. Now add in a Vector Blur node under filter. This will enable you to see what you are making. Select use nodes and backdrop on the header. Go to the node editor window make sure that you have node render passes selected. Then go to your passes panel under the render settings and make sure that the ** combined, Z, and Vector** are selected.

Go to the shading panel under materials, and select shadeless. Then you will need to add your materials. I find that a cylindrical object works well. You will start with modeling your object. This approach depends on which Render Engine you are using. Here is everything nicely organized and nodes grouped: For a point light you can actually skip the subtract. This can also be used with a point light, when the bottom most node is used instead of the geometry normal. Some artifacts appear near the edge of the area light when using constant strength, therefor a slight adjusment is required. I will contact the devs about this, since the normal has no meaning for other lights now, it could contain the direction of the object. Other light sources are not capable of providing their direction to the node system. An important note is that this solution only works with area lights, since the normal is only provided for those. Since I answered this, Blender was updated several times, and I had to update my solution also. I got a solution that is easier to understend. Now that you have asked and I tried to remember, I have a line-laser and a plane-laser node setup.

Blender light beam