Patent ID: 7433028

Claim:
A laser surveying instrument, comprising a laser projector for projecting a laser beam by rotary irradiation to form a reference plane and designed as tiltable, a tilting unit for tilting said laser projector so as to tilt the reference plane, a rotating unit for integrally rotating said tilting unit and said laser projector in a horizontal direction so as to change a tilting direction of the reference plane, a tilt setting unit for tilting said laser projector with respect to said rotating unit and for setting a target tilt angle, a tilt angle detector for detecting tilting of said laser projector, tilt sensors provided on said tilt setting unit in two directions perpendicularly crossing and for detecting horizontal position, a horizontal angle detector for detecting a horizontal rotation angle of said rotating unit, and an arithmetic control unit for controlling a rotation angle of said rotating unit based on detection results of said tilt sensors and based on detection results of said horizontal angle detector.