A laser line level is a device that is capable of projecting a straight line of colored light along a surface. These devices make use of line lasers and a number of leveling mechanisms to ensure the accuracy of both horizontally and vertically oriented lines. Laser line levels are commonly used in surveying, construction, and other industries that require the placement of highly accurate vertical or horizontal lines. A laser line level can also function as a straight edge to determine if items such as boards or shelves are warped.
Laser line levels are based around lasers that use a specific type of optics. The actual lasers are somewhat similar to laser pointers, though the optics are modified to project a straight line along a surface instead of a single dot. Most of these levels use a single straight line, though it is also possible to achieve different patterns by altering the laser optics. Simple laser line levels cast only one line, though more complex versions of these devices can have four or more lines and a variety of different patterns, such as dashes or cross hairs.
The other necessary component in the construction of a laser line level is some method of ensuring that the line is sufficiently horizontal or vertical. Spirit levels are commonly used in devices that have to be set manually. This typically comprises two spirit levels that are perpendicularly oriented so that the device can be set accurately in either a horizontal or vertical fashion. Like a straight edge, the operator must align the device according to a bubble located within the spirit level.
It is also possible for a laser line level to automatically cast a plumb or level line within certain tolerances. These automatic devices often use a type of internal plumb bob to cast a level or plumb line even if the surface it is set on it not quite flat. One method to achieve this is to use a type of swinging prism. The prism itself acts as a sort of plumb bob, and will tend to settle and cast a level or plumb line as long as the laser line level itself is held on a relatively even plane.
Laser line levels are found in a variety of different fields and industries, including survey work, construction, and woodworking. Complex and highly accurate levels are often used for delicate survey work, though inexpensive models can also be found for use in every day home repairs. Some common home uses for these devices include hanging pictures, checking to see if shelving is warped, and ensuring that tiles are laid out straight.