Laser-based measurement of distance or separation with active optical filter protection of a photo-detector to prevent its destruction

摘要

Radiation receiver with a photo-detector (22) and a sensor (11) that measures the radiation intensity. A shutter (19) arranged in front of the photo-detector is controlled dependent on the radiation intensity detected by the sensor. The shutter has a delay device (15) that is used to control transmission of radiation to the photo-detector. The invention also relates to a corresponding method using a shutter with a number of filters with different absorption properties and a distance or separation meter that uses a laser radiation source and a radiation receiver as described.