Rotating laser
A rotating laser is a device for the efficient determination of heights. It is used for construction work, machine measurements and alignment. The latter places much higher demands on the accuracy of the measuring system than its use in construction work.
description
A laser beam is deflected by 90 ° by a pentagon prism. A reference plane is created by rotating this prism around its standing axis. Depending on the design, this plane can run horizontally, vertically or at a defined angle of inclination to the earth's surface. The height of the laser beam can be detected and read at the target point with a photoelectric detector or, if the laser emits in the visible wavelength range (400–700 nm), with the naked eye on a leveling staff.
As a rule, a horizontal starting level is used. This level is leveled either manually with the help of vials or automatically with the help of inclination compensators. Plane angles deviating therefrom can be set by appropriate arrangement of deflecting prisms or inclination of the optics relative to the compensation and stabilization mechanism.
Rotary lasers usually have their own fine leveling. They can be operated remotely and work automatically. Their range is up to 500 meters; The accuracy in construction is 5 to 10 mm at a distance of 100 meters, in mechanical and plant engineering up to 0.001 mm / m. Rotating lasers usually have laser class 2 or 3R according to DIN-EN 60825-1.
The disadvantages of rotating lasers are, among other things, that air turbulence and refraction have an influence on the measurement accuracy and they are susceptible to vibrations. This is particularly important at great distances.
commitment
Use as a measuring system for machine measurement and alignment
Rotating lasers are also used to measure machines and systems ( flatness , straightness, squareness or parallelism). The requirements due to the precision of today's machine tools are many times higher than for laser systems that are used on construction sites. Accuracies of 0.01 mm / m to 0.001 mm / m must be achieved here. For systems (e.g. crane measurements or flange evenness in wind turbines), the requirements are in the range from 0.1 mm / m to 0.01 mm / m.
Rotating lasers are also used for these measuring tasks. Part of the laser beam is deflected by 90 ° by a pentagon prism. A reference plane is generated by rotating this prism about its standing axis. Depending on how the laser is set up, this plane can run horizontally, vertically or at a defined angle of inclination to the machine surface. If the reference plane is aligned horizontally to the machine surface (e.g. machine table of a machine tool), the evenness of the machine table can be determined with a corresponding receiver. With a photoelectric sensor, like a dial gauge, the altitude can be measured at various points. This is done via a display in the sensor or, for documentation, via a Bluetooth connection between the sensor and a computer on which the corresponding software is installed. In this way, the evenness of a surface is determined.
In addition, the laser has a switchable self-leveling function so that the reference plane for measurement is perpendicular to gravity and the machine is measured and / or aligned in relation to gravity. The other part of the laser beam passes the pentaprism without deflection and is therefore very precisely at right angles to the reference plane formed by the rotating laser beam. This “standing” beam can be used for measuring the straightness of an axis and for measuring the perpendicularity (e.g. tool holder of a milling machine in relation to the reference plane of the machine table).
See also
literature
- Martin Asbeck, Stefan Drüppel, Klaus Skindelies, Markus Stein: Surveying and Geoinformation . Specialist book for surveyors and geomatists. Ed .: Michael Gärtner. Gärtner, Solingen 2012, ISBN 978-3-00-038273-4 , p. 212, 227 .
