ˌplano-ˈconcave, a.
[f. plano-1 + concave.]
Having one surface plane and the opposite one concave, as a lens.
| 1693 E. Halley in Phil. Trans. XVII. 961 Whether the Lens be..Plano-Convex or Plano-Concave. 1807 Herschel ibid. XCVII. 183 The plain side of a plano-concave, or plano-convex lens. 1881 Le Conte Sight 34 And one with excess of dispersive over refractive power for our plano-concave lens. |