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5
Refraction
Refraction
•
Refraction happens when layers of air with varying degrees of temperature and
humidity deflect light as it passes through it.
•
Layers of air in a sewer pipe can refract a laser beam, causing it to bend down-
ward or produce a "dancing" effect as the beam passes through to the target.
•
Refraction is especially noticeable during hot or humid weather, but may also
occur in extrremely cold conditions when warm air from a newly opened trench
mixes with the colder air.
•
In these conditions, Leica Geosystems strongly recommends the use of a blower
assembly to reduce or eliminnate the effects of refraction. A blower mixes the
different layers of air temperature and density inside a sewer pipe, thereby
creating a uniform medium for the laser beam to pass through.
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