| 摘要 |
Apparatus for the detection of a phase boundary (10) in a transparent measuring tube (9), in particular of a liquid level in a rising tube (11) (LLD, Liquid Level Detector). The rising tube (11) is illuminated by an illumination device (15) and the light passing through the rising tube (11) is received by a light reception device (17) which converts it into signals dependent on the spatial distribution of the light intensity. A data processing unit (7) is used for processing the signals from the light reception device (17) into information on the height of the liquid level (10) in the rising tube (11). In such an apparatus very accurate detection can be achieved even for weakly and differently coloured liquids in very thin capillary-shaped rising tubes by means of an illumination device (15) which is designed for the spatially steady illumination of the rising tube (11), in particular with diffuse light, the light reception device (17) comprising an optical imaging system (18) for generating an image of the rising tube (11) in an image plane (19) and a row (20) of closely spaced light-sensitive elements in the image plane. |
