Coming soon

Since our new "Coming soon" professor still hasn't arrived, allow me to take the opportunity to tell you how this photo was made.

It is notoriously difficult to make a photo of a laser beam (most of them are photoshopped). Since laser light is highly uni-directional, the beams by themselfs can't be seen (aside from a little Rayleigh scattering). And since the air near our lasers is nearly dust free, the light has nothing to scatter from. It's possible to make it more visible by increasing the number of scattering partices in the beam, e.g. by blowing sigaret smoke in the laser beam. This makes the beam nicely visible, and the optics very dirty.

The method used here, is to darken the room completely, and use a long exposure time (minute). This by itself doesn't work, but if you take a piece of white paper, and move it frantically along the path of the laser beams, the paper itself does not leave a mark, but the very bright laser spot on the paper, sort of 'writes' the laser beam on the photo.