Laser and Optical Detectors

Optical level detectors can be used to measure the levels of solids, slurries, or opaque liquids. Their ranges are from 0.2 to 250 m (0.5 to 800 ft), and their measurement errors are about 5 mm (0.2 in.). These units are not limited in their pressure ratings and can be used from cryogenic temperatures up to those of molten metals at 1,500°C (2,732°F). 

Post-Oil Energy Technology After the Age of Fossil Fuels 

Continuous-wave laser technology directs a continuous laser beam at the target, and the distance is calculated on the basis of frequency, wavelength, and phase shift in the returning beam. It is used for short-range, extremely high-accuracy, clean-air applications usually for positioning and only infrequently for level. 

Triangulation measurement is done at an angle, with a sharply focused laser beam directed toward an object. This method is suitable for only short-range measurements, primarily for the positioning of objects and robotics, not for level sensing. 

Detection of level by measuring the time of reflection. Light travels at a speed of about 0.3 m/ 

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