| 摘要 |
The invention concerns a laser survey device which can be used inter alia in setting out roads and splits in board-and-pillar mining practice. The device has a housing which can be mounted at a survey point in a mine working in a manner allowing the housing to be rotated about a vertical axis. In the housing are laser beam directing means in the housing for projecting from the housing first and second laser beams at predetermined angles to one another and transverse to the axis. |
