| 摘要 |
PCT No. PCT/GB96/01898 Sec. 371 Date Jul. 2, 1997 Sec. 102(e) Date Jul. 2, 1997 PCT Filed Aug. 5, 1996 PCT Pub. No. WO97/06016 PCT Pub. Date Feb. 20, 1997A method and apparatus for monitoring a body having a reflective surface (1), a coating layer (2) of material transparent to visible light present on the surface (1) and producing a covert optical discontinuity in an imagewise distribution on the layer (2); the imagewise distribution is such that it is visible via polarized light (7) and viewing through a polarized filter (8). |
