Bright Field Microscope

The bright field microscope is the ordinary compound microscope used in almost every school and college laboratory, and it is the workhorse instrument for routine cell observation. Its light source - typically a CFL or LED lamp built into the base - shines upward through a condenser lens, which focuses the light rays onto the specimen sitting on a microslide on the stage. The light then passes straight through the specimen and up through two separate lens systems in sequence: first the objective lens (the one closest to the object), which produces the first, 'primary' magnification as a real, inverted image, and then the eyepiece lens (the one closest to the observer's eye), which magnifies that image a second time into a 'secondary' magnification that is virtual and, again, inverted relative to the original object. A single bright field microscope usually carries four objective lenses of different power - 5X, 10X, 45X and 100X - mounted on a rotating nosepiece so the user can switch magnification simply by turning to a different lens. Because different parts of a specimen absorb light differently, some natural contrast appears automatically, but that …