| 摘要 |
<p>PCT No. PCT/EP83/00082 Sec. 371 Date Nov. 22, 1983 Sec. 102(e) Date Nov. 22, 1983 PCT Filed Mar. 22, 1983 PCT Pub. No. WO83/03442 PCT Pub. Date Oct. 13, 1983.The device consists of an inspection glass (3) inserted in the door (1), a semi-transparent mirror (5) which is arranged inclined behind the inspection glass (3) and which faces the inspection glass (3) with the semi-reflecting side (6), and an optical receiver (7) which is located in the axis of reflection of the mirror (5). The invention is used in the building industry.</p> |
