| foci | Plural of focus. The origin or centre of a disseminated disease. (16 Dec 1997) |
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| focimeter | An instrument to measure the power and cylindrical axis of a spectacle lens. Synonym: focimeter, vertometer. Origin: Lens + G. Metron, measure (05 Mar 2000) |
| conjugate foci | <microscopy> In an image-forming system, two fields are said to be conjugate with each other when two or more object fields are simultaneously in focus in a single plane, for example, in Kohler illumination the field diaphragm, specimen and ocular front focal plane are conjugate foci as are the filament, condenser aperture diaphragm, objective back focal plane and ocular front focal plane(when a Bertrand lens is used). (05 Aug 1998) |
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