light from the specimen and its surroundings is collected to form an image against a bright background
Brightfield imaging is the simplest form of microscopy where light is either passed through, or reflected off, a specimen. Illumination is not altered by devices that alter the properties of light (such as polarizers or filters).
In biological applications, brightfield observation is widely used for stained or naturally pigmented or highly contrasted specimens mounted on a glass microscope slide. The specimen is illuminated from below and observed from above. The specimen appears bright, but darker than the bright background. This technique is widely used in pathology to view fixed tissue sections or cell films / smears. Brightfield imaging is not very useful for unstained living cells or unstained tissue sections as, in most cases, the light passes through transparent or translucent samples with little or no definition of structure.
Light is reflected from opaque samples and this is exploited in industrial environments where brightfield imaging is used for wafer inspection and liquid crystal board inspection.
All light microscopes are capable of brightfield imaging.
For biological applications, Nikon's upright microscopes Eclipse Ni / Eclipse Ci provide superb brightfield images ideal for the observation of fixed, stained specimens. These microscopes additionally provide a wealth of other imaging capabilities to meet the needs of both routine, clinical, and research applications.