Target instrument and surveying system

1. A surveying system comprising a laser scanner for scanning a distance measuring light and for acquiring point cloud data and a target instrument having a target for reflecting said distance measuring light, wherein said target is a sphere having a known diameter, said laser scanner comprises a distance measuring module for projecting said distance measuring light, for receiving a reflected distance measuring light and for performing a distance measurement, an optical axis deflector which enables to two-dimensionally deflect said distance measuring light, and an arithmetic control module for controlling said optical axis deflector, and wherein said arithmetic control module is configured to perform a circular scan on a surface of said target by said optical axis deflector, to obtain a center of said target based on the point cloud data acquired by said circular scan and said diameter, and to measure a distance of the center of said target.

2. The surveying system according to claim 1 , wherein, with respect to said moving target, said optical axis deflector is configured to direct a center of said circular scan to the center of said target in such a manner that distance measurement values of an entire circumference obtained by said circular scan become equal to each other.

3. The surveying system according to claim 1 , wherein said target instrument further comprises a pole of which end indicates a measuring point and an air bubble tube provided on said pole, wherein the center of said target is positioned on an axis of said pole and is provided at a known position from the end of said pole, and wherein said laser scanner is configured to measure the center of said target and to carry out a measurement of said measuring point in a state where said pole is vertically supported.

4. The surveying system according to claim 1 , wherein said optical axis deflector includes a biaxial galvanometer mirror.

5. The surveying system according to claim 1 , wherein said optical axis deflector has a reference optical axis, said optical axis deflector comprises a pair of optical prisms rotatable around said reference optical axis and motors which individually and independently rotate said optical prisms, and wherein said arithmetic control module is configured to control a deflection of a distance measuring light by said optical axis deflector by controlling a rotating direction, a rotation speed and a rotation ratio of said pair of optical prisms, to perform a two-dimensional scan with a scan center optical axis as a center, and to control a deflection of said scan center optical axis with respect to said reference optical axis.

6. The surveying system according to claim 1 , wherein said arithmetic control module is configured to scan said distance measuring light in a scan pattern with at least one intersection or to scan said distance measuring light in a circular pattern by said optical axis deflector.

7. The surveying system according to claim 6 , wherein said arithmetic control module is configured to scan said distance measuring light by said optical axis deflector in such a manner that said intersection is formed on said target and a part of said scan pattern crosses said pole, to obtain the center of said target based on the point cloud data acquired by scanning said target, to carry out a measurement of said target, and to measure a tilt of said pole based on the center of said target and a distance measurement value obtained by crossing said pole.

8. The surveying system according to claim 6 , wherein said arithmetic control module is configured to carry out a sighting and a tracking of said target by said circular scan and to carry out a measurement of said target in a scan pattern with at least one intersection.