An Etymological Dictionary of Astronomy and Astrophysics
English-French-Persian

Describing a lens with two concave faces.

→ bi-; → concave; → lens.

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."

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.

→ concave; → grating.

A lens which is thinner at the center than at the edges and diverges the light rays.

→ concave; → lens.

A mirror whose surface is curved inward and converges the light rays.

→ concave; → mirror.

A diverging lens having one surface convex and the opposite surface concave.

→ convex; → concave; → lens.

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.

→ plano-; → concave; → lens.