dark-field illumination


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dark-field illumination

[′därk ‚fēld ə‚lüm·ə′nā·shən]
(optics)
A method of microscope illumination in which the illuminating beam is a hollow cone of light formed by an opaque stop at the center of the condenser large enough to prevent direct light from entering the objective; the specimen is placed at the concentration of the light cone, and is seen with light scattered or diffracted by it.
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References in periodicals archive ?
Dark-field illumination results in most of the light falling outside of a camera's field of view (FOV).
In other words, oblique illumination covers every lighting possibility between bright-field and dark-field illumination. Transmitted oblique illumination is useful for inspecting translucent polymers, while incident oblique illumination can be used for large samples like human bones, which tend to be highly contoured.
It has been suggested that Leeuwenhoek might have used some simple means of dark-field illumination to visualize details such as flagella on bacteria.