Unformatted text preview: ty environment, it is to be expected that the lenses of optical proximity
sensors and reflectors may become contaminated. Example By means of the following example using a retro-reflective sensor, you will discover
how much the function of a optical proximity sensor depends on whether its lens
and reflecting device are clean. Let us assume that the lens and the reflector are
dimmed by deposits of dirt by 10 %. This is a value which is easily achieved. This
level of pollution is barely detectable by visual means. Because the light beam of a
retro-reflective sensor has to penetrate this contamination four times, the irradiated
light is weakened from 100 % to approx. 66 %. Almost a third of the effective
emission capacity is used up as a result of this slight contamination.
With optical systems, it is always important to ensure that the lenses and/or
reflectors are clean. If required, additional measures must be taken to prevent rapid
or high build-up of contamination (e.g. blowing by compressed air, installing a dust
trap). The maximum contamination permissible depends o...
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- Spring '12
- pH, proximity sensors, Festo Didactic GmbH, Festo Didactic GmbH & Co