Fr.: lentille biconcave
Describing a lens with two concave faces.
Of a surface, curving inward.
From L. concavus "hollow," from → com- intensive prefix + cavus "hollow;" PIE base *keu- "a swelling, arch, cavity."
Kâv "hollow," verb kâvidan (kâftan) "to dig; to examine, investigate," cf. L. cavus "hollow" (E. derivatives: cavity, concave, cave, excavate), Gk. koilos "hollow," Armenian sor; PIE *kowos "hollow."
turi-ye kâv (#)
Fr.: réseau concave
A → diffraction grating ruled on a concave spherical mirror that eliminates chromatic aberration and transmits regions of the spectrum, such as the ultraviolet, which is not transmitted by glass lenses.
adasi-ye kâv (#)
Fr.: lentille concave
A lens which is thinner at the center than at the edges and diverges the light rays.
âyene-ye kâv (#)
Fr.: miroir concave
A mirror whose surface is curved inward and converges the light rays.
Fr.: lentille convexo-concave
A diverging lens having one surface convex and the opposite surface concave.
adasi-ye taxt-kâv (#)
Fr.: lentille plano-concave
A → divergent lens composed of one concave surface and one plane surface. This type of lens has a negative focal point and produces a → virtual image.