REFRACTION ISSUES
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Product types: All Rotary and Cross line laser levels
Although there will always be the 0.1% of products that develop a fault, 99.9% of the technical
enquiries we receive relating to “incorrect levels”, “random positions”, “out-of-level” or “Detector
not picking up the beam correctly” transpire to being Refraction of the laser beam.
Laser levelling equipment is used by many diff erent industries in various work-site
environments. Users should be aware of the possibility of refraction problems, when using this
type of equipment.
“Refraction” is the phenomenon where light is transmitted but moves direction when it passes
from one medium to another e.g. through air then glass or water. This is why a pond of water
appears shallower than it actually is or when you shine a torch at a window and the beam
bounces off to another position. In the same way, this refraction can aff ect the correct setting-
out, when using laser beams.
An easy example to understand is if, for example, a rotary laser is operated with a double-glazed
window behind it. The true level position can be refracted and the deviation can be appreciable,
even over small distances. In some instances, a double beam position can occur and the wrong
level marked.
Our advice is to be aware of this and take appropriate care when setting out with your laser
level,
both
indoor & outdoors.
A simple
fi x
(if the laser cannot be moved or lowered) is to position a simple brown cardboard
cover over the laser level on the side towards the refraction surface.
The following surfaces can potentially be problematic:
All glazing - single, double or treble glazed units. Patio / Bi-fold glass doors etc.
Glazed offi ce partitioning.
Vehicle or Site Plant - glass windows & windscreens. (Curved windows are the worst)
Panel van sides - wet surfaces.
Mirrors & mirrored surfaces.
Stainless steel, shiny aluminum panels & refl ective Celotex panels
Water – fountains, water displays, rivers, dams and weirs etc.
In addition, please be aware of the eff ects of amber & green warning beacons on plant &
equipment. This “strobe eff ect” is a known problem and can aff ect all types of laser detectors to
give erratic readings.
Our main advice is just to be site-aware when using laser levelling equipment, to ensure the
reliable and accurate setting-out of your jobs.
It’s also important to understand that refraction of the beam, occurs with all lasers
regardless of cost and or brand purchased.
