| 释义 |
Foucault knife-edge test Foucault knife-edge test[fü′kō ′nīf ‚ej ‚test] (optics) Test of a lens or a concave mirror in which a pinhole source is placed at twice the focal length behind the lens or at the mirror's center of curvature, the eye is placed at the image of the pinhole, and defects in the lens or mirror result in irregular darkening of the image when a knife edge is moved across the image immediately in front of the eye. |