① There is a possibility that correct distance measurement may be impossible by dispersion or reduction of laser beam when the laser beam comes into the target from diagonal angle.
② There is a possibility that the instrument cannot calculate correctly when receiving
reflected laser beam from forth and back directions in case of measuring the target on the road.
③ There is a possibility that synthesized values are calculated and the distance may become
longer or shorter than the actual one when the operator measures the target of slope or sphere or rugged shape.
④ There is a possibility that the instrument cannot calculate correctly collecting the reflected
laser beam from a man or a car that comes and goes in front of the target.