38
8018478/YWL5/2018-06| SICK
O P E R A T I N G I N S T R U C T I O N S | NAV245
Subject to change without notice
3
PRODUCT DESCRIPTION
3.10.3
Distance between the
NAV245
and the object/surface to be measured
The measuring range of the NAV245 starts 0.5 m in front of the lens (light emission window).
With recessed installation of the NAV245, it is important to consider how the laser beam
expands as the distance increases in order to avoid incorrect measurements.
If the device is mounted in an unfavorable position, depending on the distance, this could
therefore mean that objects in the scanning area are detected constantly as they are hit by
the laser beam.
Fig. 25: Beam expansion and safety supplement
The optical axis is located around 198 mm above the lower edge of the housing when the
NAV245 is mounted vertically. This is used as a reference plane for the distance that must
be maintained from the wall.
The range-dependent beam expansion can be calculated using this formula:
Beam diameter = (distance (mm) × 15.0 mrad) + 8 mm
The table below provides a few values as examples:
Table 8: Beam diameter at different distances from the NAV245
When assessing whether the laser beam can meet an object, the distance from the half
beam diameter to the optical axis is used.
Important
A safety supplement of 5 mm per meter is used above and below (see
Recommendation
You can use a value of 25 mm per meter to make it easier to calculate the sum from the
beam expansion and the safety supplement.
Safety supplement
5 mm/m
Optical axis
Expanded
laser beam
Continuous detection from 15 m
Distance [m]
5
10
15
20
25
30
35
40
45
50
Beam diameter [mm]
83
158
233
308
383
458
533
608
683
758
