| 摘要 |
PCT No. PCT/EP97/05869 Sec. 371 Date Jun. 24, 1998 Sec. 102(e) Date Jun. 24, 1998 PCT Filed Oct. 23, 1997 PCT Pub. No. WO98/18026 PCT Pub. Date Apr. 30, 1998An optical monitoring means comprises a plurality of pattern fields, which are arranged at one end of the area to be monitored, objectives at the other end of the area to be monitored and which are respectively associated with the pattern fields, reflectors, which deflect the image rays from the objectives onto a image projection surface, a sensor means, onto which the objectives throw an image of the pattern field, and which scans the image and feeds corresponding signals to a signal processing means, which ascertains whether the image received by the sensor means possesses the same optical characteristics as the pattern fields. As an alternative the monitoring means comprises a series of pattern fields is arranged at opposite sides of an area to be monitored, two units, which respectively comprise an objective and a reflector, are arranged at diagonally opposite corners of the area to be monitored, the units are so rotatably arranged that one objective in each case scans the pattern field arranged opposite to it, and that opposite each reflector a sensor means is placed, onto which the objectives throw the image of the pattern field, and which scans the image and feeds corresponding signals to a signal processing means, which ascertains whether the image received by the sensor means possesses the same optical characteristics as the pattern fields. |
