Business / Machine Shop / Concave: A curved depression in the surface of an object.

Concave Lens

Entertainment / Photography / Concave Lens: See bi-concave lens. MORE

Bi-Concave Lens

Entertainment / Photography / Bi-Concave Lens: Simple lens or lens shape within a compound lens, whose surfaces curve toward the optical center. Such a lens causes light rays to diverge. MORE

Reflecting Telescope

Entertainment / Photography / Reflecting Telescope: Telescope using a concave parabolic mirror to increase focal length and focus light at a point. MORE

Radius Gage

Business / Machine Shop / Radius Gage: Any one of a number of small, flat, standard-shaped metal leafs or blades used for checking the accuracy of regular concave and convex surfaces. MORE

Negative Lens

Entertainment / Photography / Negative Lens: Is a simple concave lens that causes rays of light to diverge away from the optical axis. MORE

Meniscus Lens

Entertainment / Photography / Meniscus Lens: Is a simple lens consisting of a single piece off glass, thicker at the center than at the edges. It has one concave and one convex face. MORE