beam from mirroring surfaces
with scratches
· multiple reflections at edges
· dark coloured objects, which
do not reflect enough light
· extreme variation of the sur
face finish
· no object within the measu
ring range
· interrupted laser beam and
shadows
· partly transparent surfaces (si
milar to glass or synthetic ma
terial
· for each measurement point the
corresponding intensity has to be
evaluated in addition to the dis
tance information {X;Z} in order to
obtain valid measurements
Application Notes
Measurement setup
· The resolution degrades with
increasing distance between
object and scanner, especially
with large scan ranges
· Best results are achieved when
the scanner beam is focused
rectangular to the objects sur
face Measurements with angu
lar deviation of up to 60° are pos
sible
· In order to avoid radio interfe
rence or noise, the scanner
should be electrically isolated
from the mounting surface
· Scanners with detached sensor
head are perfectly matched to
their individual electronic box
and should not be interchan
ged or mixed up
· The interface wire should not
be exchanged by a longer or
shorter one
Scanner Configuration
Adjustment of shutter speed
The shutter speed is regulated
depending on the brightness of
the reflected signal The diffuse
reflection of the objects surface is
influencing the shutter speed Sur
faces with more diffuse reflections
will yield brighter profiles, thus cau
sing shorter shutter times Darker
surfaces result in longer shutter ti
mes accordingly
Due to an automatic Gain Control
of the Video signal, the shutter
speed can be reduced, hence cau
sing of some extra noise
Depending on the reflections of the
surface, shutter speeds between
1/47,000 sec and 1/225 sec are
typical
With the supplied configuration
software, shutter speed and video
gain control can be adjusted (see
software description)
External Synchronisation
In order to synchronize the measu
rement exactly with a running pro
cess, it is possible to trigger the
scanner externaly The maximum
scan rate is 100 halfscans/sec
The measurement object is scan
ned 100 times / sec If the object is
not moving or moving very slowly,
then 2 consecutive measurements
can be integrated to one measure
ment, which will result in 2-times
the resolution in X-direction (fig 5)
Security advices
When setting up the Scanner it is
important that the Caution sign will
be visible very well
The power of the Laserbeam is so
low, that damage to the human eye
ist prevented by the wink reflex of
the eyelid It is harmless to view in
to the diffuse reflected laser line
nterfaces
Digital Outputs:
The scanner can output the digital
profile-data via the integrated
Ethernet-Interface Detailled infor
mation about interfaces and soft
ware-control can be found in the
respective hardware- and softwa
re manuals
Signal nputs:
The following functions can be ad
justed via Ethernet -Interface:
· Time of exposure
· Video-Gain
· Trigger-input
· Trigger with rising edge
A single measurement ca be trig
gered with the trigger input During
measurements no new triggers will
be accepted
Synchronization of two
Scanners
Option 1: alternating mode
Option 2: sync mode
Sync inaccuracy +/-15 µsec
Master slave mode can be defined
via jumpers onthe ISA-board, via
external wires with the Blue Box
The desired option can be selected
-7-
Fig 4
Z
Z
Z
X
X
X
1st half frame
2nd half frame
full frame
Fig 5
X
Z
I
X
Sensor
Measured object
Scan data Z(X)
Intensity I(X)
Area to suppress
Option 1 Option 2
Fig 7
MIKROELEKTRONIK GmbH · Tel. +49 89 / 327150-0 · F x +49 89 / 319 20 23 · www.MELsensor.de
Fig 6
CAUTION
LASER RADIATION
DO NOT STARE INTO BEAM
CLASS II LASER PRODUCT
