| 摘要 |
The apparatus or the measuring head (26) comprises a housing (30), in which a light source (32) and a light-sensitive element (34) are arranged. From the light source (32) light energy is directed via optical fibres over a profile (24) to be monitored. Light energy is picked up by optical fibres (44), which direct the light to the light-sensitive element (34). Due to the arrangement of optical fibres, the measuring head can be made very thin, so that it can be arranged directly in the hold-up area ahead of a calibrating device. In order to eliminate disturbing light effects from the surrounding area, a filter (46) is arranged in front of the light-sensitive element (34). The fine setting of the measuring head (26) is performed by means of a stepping motor and the controlling of the hauling-off device of the extruder is performed with a delay after detecting the tendency of a proportional change in the profile ahead of the calibrating device. <IMAGE> |
