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Solution: Turn away optical axis from the external source or install an orifice in the light beam Fig. 6.5.7: Avoiding interfering light 96 © Festo Didactic GmbH & Co. KG • FP 1110 6. Optical proximity sensors A reflecting surface in the vicinity of some types of optical proximity sensors can
lead to interference, if stray light from the emitter reaches the receiver via a
reflecting surface, see Fig. 6.5.8. If diffuse sensors are used, then a reflecting
background (e.g. light anodised aluminium parts) can create problems. a) b) a) Problem: Reflecting surfaces in surrounding area.
b) Solution: Cover reflecting surfaces or reflection by means of orifices.
Further possibilities are:
– To set the optical axis at an angle in order to "deflect away" the interfering reflection.
– To reduce the sensitivity of the receiver. Fig. 6.5.8: Avoidance of reflective interference The lenses of optical proximity sensors must be screened against dirt or regularly
cleaned (e.g. with jets of compressed air). If dirt could cause interference, basic
consideration should be given to whether alternative proximity sensors less affected
by dirt should be used. © Festo Didactic GmbH &a...
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- Spring '12