Answer:
dark-field microscopy
Explanation:
A darkfield microscope can be regarded as a brightfield microscope with a significant modification to condenser. There is an opaque disk, with a diameter of about 1cm placed in between the illuminator and condenser lens, the disk responsible for the blocking of most of the light from the illuminator, passing through the condenser to objective lens , which will then form hollow cone of light that has its focus on the specimen. Using a darkfield microscope the light that get to the objective is the only refracted or reflected light of structures in the specimen. And the image formed usually display a bright object with a dark background.
It should be noted that darkfield microscope is a type of microscopy works by allowing only light waves that have reflected from or refracted though the sample to enter the lens system.
