Device for obscuration measurement in monitoring area at road in tunnel, has evaluation unit for selecting light-sensitive pixel element of matrix image sensor, where light source lies in receiving area of element

摘要

The device has an evaluation unit i.e. controller (24), to calculate an extinction coefficient based on a distance between a light source (26) e.g. halogen lamp, and a light receiving unit and decrease in measured intensity with respect to reference intensity of light incident on the receiving unit. The source is arranged in a monitoring area (22). The evaluation unit selects a light-sensitive pixel element of a matrix image sensor (20) e.g. charge-coupled device sensor chip, where the source lies in a receiving area of the element. The element is provided as the receiving unit. An independent claim is also included for a method for obscuration measurement in a monitoring area.