Dark Field Microscope, can creat a contrast between the object and surrounding field, such that, the background is dark and the edge of the object is bright. It can show some transparent & very small objects clearly, The resolution under dark field microscope can raise up to 0.02~0.004um from normally 0.45um under bright field view. Dark field microscope can be upgraded from normal microscope by adding a dark field condenser, and higher intensity lamp, some times a dark field objective with iris diaphragm which can reduce the aperture less than 1.0.