An illumination device provides temporally, spatially and angularly stable illumination for microscopic evaluations. An arc lamp serves as the light source. An input optical train gathers and focuses the light through an aperture stop to place an image of the arc incident on an input aperture of...http://www.google.com.au/patents/US5677762?utm_source=gb-gplus-sharePatent US5677762 - Apparatus for illumination stabilization and homogenization
