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Unformatted text preview: example, can be 150 µs and parts of up to
2 mm in diameter can be resolved. 242 © Festo Didactic GmbH & Co. KG • FP 1110 15. Special designs and variants of proximity sensors 15.2.3 Laser barrier sensors
Light emitting diodes (LED) are mostly used as the light source for optical sensors.
However, by using laser diodes, it is possible to construct laser sensors, which have
the following advantages:
• Extremely wide range by means of concentrating the laser beams
• Very narrow and precise response range over great distances
With laser beams having a cross section of 18 mm x 10 mm, it is possible to detect
objects at ranges of more than 200 m for instance. With shorter ranges of for
example 2 m, it is possible to detect an object of only 0.3 mm diameter. Such
extremely small response areas are particularly useful for accurate approaching and
setting of tools and workpieces. 15.2.4 Polarised retro-reflective sensors
Where retro-reflective sensors are used to detect highly reflective objects, the
proximity sensor is unable to distingui...
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- Spring '12