esp. of glasses, lenses, mirrors, etc. of this shape used for optical purposes.

Of a lens, part of an animal or plant, etc.: having one surface plane and the opposite one convex. Also occasionally as n.: a planoconvex lens.

in combination = Concavely, concave and ——, as in concavo-ˈconcave n. concave on both sides. concavo-ˈconvex n. concave on one side and convex on…

In combination = Convexly, convex and ——, as in convexo-concave n. convex on one side and concave on the other, and thickest in the centre (cf. conc…

Powerful in operative effect. Of a lens: having great magnifying or corrective power. Hence: having such a lens or lenses.

Free from aberration; spec. applied to a compound lens which is free from spherical aberration or divergence of rays of light from the focus.

Of a lens, eyeglass, etc.: giving a wide field of view; spec. (of a lens) concavo-convex.

Of a lens: biconvex. rare.

Divided into or comprising several zones; occupying or involving several zones.

Extending only a short distance inward from the surface or from the front towards the back. Of a lens: Having slight convexity or concavity.

Designating a Fresnel lens in the first of a series of orders based on their focal length and size; (of a lighthouse) employing such a lens.

= periscopic, adj.

Having or producing normal vision; yielding an image free from optical distortion; spec. of binocular vision: without the reversal of convexity and…

Designating a spectroscope in which light leaves in the same line as it enters, undergoing no overall deflection. Obsolete. rare.

That has been overcorrected.

(of a lens) having a spherical and a cylindrical surface.

designating a lens or optical instrument (esp. a telescope) having a large maximum relative aperture.

Of a lens or other optical system: that transfers an image without bringing it to a focus, i.e. so that rays entering parallel emerge parallel…

Epithet of an improved form of achromatic lens invented by Abbe. Also as n.: an apochromatic lens; in Photography further shortened to ˈapochroˌmat n.…

Not astigmatic; free from astigmatism: applied to a compound lens so constructed as to correct the astigmatic aberration.

(a) adj. (of a compound lens or other optical system) configured in such a way that the ray passing through the centre of the aperture stop is…

Designating or relating to a lens or optical instrument that brings to the same focus both visible light and light that can only be detected…

= aspheric, adj.

Not spherical.

Having or relating to several foci or a range of focal lengths.

Of a surface of a lens: plane, flat.