US Patent 7814670 Laser level detection system

A laser level detection system which detects a reference plane of laser at an arbitrary position includes a plurality of level detection units and an operation unit which displays a detection result of each of the level detection units and can operate each of the level detection units, and the laser level detection unit, which has detected the reference plane of the laser, outputs the detection result and an own identification signal of the level detection unit, and the operation unit displays the detection result and a receiving result of the identification signal of the level detection unit.