'Making Darkfield Illumination is easy'
by Mike Samworth and Wim van Egmond
A mirror of the original article http://www.micropolitan.orgmaking.html
on Wim van Egmond's web site.
The advantage of darkfield illumination is that you can see details that are normally not resolved by the microscopes objective. You can't see the actual detail but because it reflects light you can see it. A nice analogy here is that of dust in a room. In a well lit room you do not see the very small dust particles. However, if the lights go out, a beam of light from an acute angle makes these same particles visible. Besides the optical advantages darkfield illumination is very beautiful and gives an almost science fiction like image.