4-8
4 Measuring
4.4 PSV-G-500 Geometry Scan Unit
4.4.1 Introduction
The geometry scan unit is in the scanning head. It helps you to determine the
distance to the object under investigation. If you make a geometry scan,
within a few milliseconds the system switches from the vibrometer laser to the
geometry laser and determines the exact distance to the object.
Measurement
principle
The distance measurement in the geometry scan unit is based on the transit
time technique. The distance is determined based on the time the light needs
to reach the object and to return from it.
Optimal
measurement
In the same way as it is with a vibrometry measurement, the detected
radiation is independent from the scattering characteristic of the surface and
the distance. To get an optimal measurement result you should use a diffuse
white surface in the close-up range (below 1.5 m) and a retro-reflective film at
longer distances.
INFORMATION
If you use a retro-reflective film in the range below 1.5 m, the sensor may
overload and affect the measurement result. Therefore, use retro-reflective
film only at distances longer than 1.5 m.
You can make a distance measurement without retro-reflective film. If retro-
reflective film is on the object under investigation, set the scan points onto the
retro-reflective film or cover the retro-reflective film. If retro-reflective film is in
the proximity of the scan points, the measurement result can be falsified,
although the geometry laser is not pointed onto the retro-reflective film. Pay
attention to the following information when you carry out a distance
measurement.
Object under investigation
Distance to the
object
Precautions
< 1.5 m Cover the retro-reflective film in any
case. With optically poorly reflective
surfaces treat the object with white
paper and carry out the distance
measurement.
≥ 1.5 m Carry out the distance measurement on
the retro-reflective film.
Planar object
Retro-reflective film
Geometry laser
To Next Page
Loading...
Need help?
General
