Measuring through glass surfaces will not produce repeatable or accurate results. Unless the glass surface has very specific coatings, back reflections could be present and these would affect the radial measurements. Even if the glass surface does have proper coatings to prevent or minimize this, the glass has a different index of refraction than the air the beam is travelling through.
This index of refraction change can result in an error in the radial distance measurement and will also result in the beam “bending” or no longer travelling a straight path from the tracker to the target. This bending of the of the beam will affect the measurements from the scanner. The nature of the bend will also change as the angle the beam enters the glass window changes resulting in a loss of both accuracy and repeatability.
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