Editing Laser level (section)

==Rotary laser level==
A rotary laser level is a more advanced laser level in that it spins the beam of light fast enough to give the effect of a complete 360 degree horizontal or vertical plane, thus illuminating not just a fixed line, but a [[horizontal plane]].<ref name="UrenPrice2010">{{cite book|author1=J. Uren|author2=W.F. Price|title=Surveying for Engineers|url=https://books.google.com/books?id=iQEdBQAAQBAJ&pg=PA543|date=17 March 2010|publisher=Palgrave Macmillan|isbn=978-1-137-05279-7|pages=543–}}</ref> The laser beam projector employs a rotating head with a [[mirror]] for sweeping the laser beam about a vertical axis.  If the mirror is not self-leveling, it is provided with visually readable level vials and manually adjustable screws for orienting the projector. A staff carried by the operator is equipped with a movable sensor, which can detect the laser beam and gives a signal when the sensor is in line with the beam (usually an audible beep). The position of the sensor on the [[graduated (measurement)|graduated]] staff, also known as a grade rod, or story pole, allows comparison of elevations between different points on the terrain. Most laser levels are used in the construction industry.