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Instructions for Operating
optoNCDT 1402
Instructions for Operating
9.
Reflection Factor of the Target Surface
9.1
In principle the sensor evaluates the diffuse part of the reflected laser light (see Fig. 21).
Laser beam
Ideal diffuse reflection
Real reflecion
Direct mirror
reflecion
Laser beam
Laser beam
D
2
D
Reflection factor of the target surface
Fig. 21:
A statement concerning a minimum reflectance is difficult to make, because even a small diffuse fraction can
be evaluated from highly reflecting surfaces. This is done by determining the intensity of the diffuse reflection
from the CCD array signal in real time and subsequent compensation for intensity fluctuations, see Chap. 3.2.
Dark or shiny objects being measured, e.g. black rubber, may require longer exposure times. The exposure
time is dependent on the measurement rate and can only be increased by reducing the sensor’s measure-
ment rate.
Error Influences
9.2
Light from other Sources
9.2.1
Thanks to their integrated optical interference filters the optoNCDT1402 sensors offer outstanding perfor-
mance in suppressing light from other sources. However, this does not preclude the possibility of interference
from other light sources if the objects being measured are shiny and if lower measurement frequencies are
selected. Should this be the case it is recommended that suitable shields be used to screen the other light
sources. This applies in particular to measurement work performed in close proximity to welding equipment.
