In surveying, and construction the laser level is affixed to a tripod, levelled and then spun to illuminate a horizontal plane. 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 moveable 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 staff allows comparison of elevations between different points on the terrain.
A tower-mounted laser level is used in combination with a sensor on a wheel tractor-scraper in the process of land laser leveling to bring land (for example, an agricultural field) to near-flatness with a slight grade for drainage.
- Rando, et al "System for controlling attitude of laser beam plane", U.S. Patent 4,062,634, December 13, 1977.
Retrieved from "http://en.wikipedia.org/wiki/Laser_level"