Abstract: Disclosed is a rotational laser apparatus capable of setting an obliquity without requiring a high accuracy light receiver or a complex optical system for separating different polarized fluxes. The rotational laser apparatus comprises a plurality of reflected sections provided on a target in a direction transverse to scanning laser beam. The reflected planes is disposed in such a manner that a time series arranging state for pulses of the light receiving signal differs between a case that the scanning laser beam intersects the reflected sections from one side to the other side and a case that the laser beam intersects the reflected sections from the other side to one side, with identical scanning direction of the scanning laser beam, The control part includes a judging circuit for judging an operated direction of the oblique mechanism based on the time series arranging state for pulses of the light receiving signal.

Abstract: Disclosed is a rotational laser apparatus capable of setting an obliquity without requiring a high accuracy light receiver or a complex optical system for separating different polarized fluxes.

Abstract: The laser survey instrument according to the present invention comprises a rotary laser device and a photodetector for receiving a laser beam, wherein the rotary laser device comprises a light source unit for emitting the laser beam, a rotator for projecting the laser beam toward the photodetector by rotary irradiation, detection means for detecting status of the rotary laser device, and a control unit for changing the number of rotations of said rotator based on the result of detection from the detection means in order to transmit the detection result from the detection means to the photodetector, the photodetector comprises a photodetection unit for receiving the laser beam from the rotary laser device and for issuing a photodetection signal, display means having a display corresponding to the photodetection signal, and judging means for detecting the number of rotations of the laser beams from the photodetection signal of the photodetection unit and for operating the display means according to the rotating