| FADF | fluorescent antibody dark field |
|---|---|
| FEER | field echo with even echo rephasing |
| FET | field-effect transistor; forced expiratory time |
| FF | degree of fineness of abrasive particles; fat-free; father factor; fecal frequency; fertility factor... |
| FFE | fast field echo; fecal fat excretion |
| periscopic lens | A lens with 1.25 D base curve. (05 Mar 2000) |
|---|---|
| photochromic lens | A light-sensitive spectacle lens that reduces light transmission in sunlight and increases transmission in reduced light. (05 Mar 2000) |
| minus lens | A diverging minus power lens. Synonym: minus lens. (05 Mar 2000) |
| collimating lens | <physics> A lens used to produce a collimated beam from a light source. With a true point source on the axis the beam would be an axial tube of parallel rays With practical sources having real area the beam will be a diverging cone of parallel rays from each light point, this beam still has special properties and can be collected again by a good lens. (05 Aug 1998) |
| plan apochromatic objective lens | <physics> A modern, high-numerical aperture microscope objective lens designed with high degrees of corrections for various aberrations. It is corrected for spherical aberration in four wavelengths (dark blue, blue, green, and red), for chromatic aberration in more than these four wavelengths, and for flatness of field. A single Plan Apo objective may contain as many as 11 lens elements. (05 Aug 1998) |
| compound lens | An optical system of two or more lenses. (05 Mar 2000) |
| concave lens | A diverging minus power lens. Synonym: minus lens. (05 Mar 2000) |
| concavoconcave lens | A lens that is concave on two opposing surfaces. Synonym: concavoconcave lens, double concave lens. (05 Mar 2000) |
| concavoconvex lens | A converging meniscus lens that is concave on one surface and convex on the opposite surface. (05 Mar 2000) |
| condenser or condenser lens | <physics> A term applied to lenses or mirrors designed to collect, control, and concentrate radiation in an illumination system. (05 Aug 1998) |
| multifocal lens | A lens with segments providing two or more powers; commonly, a trifocal lens. (05 Mar 2000) |
| plus lens | A converging lens. Synonym: plus lens. (05 Mar 2000) |
| contact lens | A lens that fits over the cornea and sclera or cornea only; used to correct refractive errors. (05 Mar 2000) |
| contact lens solutions | Sterile solutions used to clean and disinfect contact lenses. (12 Dec 1998) |
| convex lens | A converging lens. Synonym: plus lens. (05 Mar 2000) |