Laser Overview Preface | What is a Laser? | The Construction Laser Advantage

Preface:
Lasers have been used in the construction industry for over three decades. If you're in the construction industry you've probably heard of them, and in most cases either used or have been on a jobsite where they were being used. But what makes them such a vital part of most contractor's inventory? The basic functions they perform have been accomplished for years by tried-and-true tools like carpenter's levels, plumb bobs, and chalk lines, so why the change?

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What is a laser?:
There are two types of laser beams used in construction, visible beam and infrared. Visible beams (635nm to 532nm for the Green Beam®) are generally used in the interior and utility/pipe markets where they take the place of other and more cumbersome visual references (see The Construction Laser Advantage). Infrared lasers are used in general construction (concrete, small excavation), and heavy earthmoving markets. Infrared lasers use the same 5mW output but they're barely visible or completely invisible to the human eye (680nm and lower), yet they have the ability to travel through, and be effected less, by atmospheric conditions at far greater distances than visible beams. This makes them perfect for large jobsites or land leveling applications.

Although the harmfulness of these lasers is extremely small, care should always be taken when using a visible beam laser in open areas. Never set a visible beam laser in an open area at a height that may strike machine operators, workers, or motorists in the eye. Most visible beam construction lasers are Class II and limited to 5mW total output by law. Infrared lasers are Class I lasers, and pose no danger from incidental eye exposure.

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The construction laser advantage:
As mentioned above, lasers are replacing many traditional tools. That's not to say that the traditional tools weren't up to the job. It's just the fact that every tool has its limitations, including lasers (See Construction Lasers and The Topcon Advantage). Qualities inherent in lasers have overcome many of the limitations of traditional tools. Take for example a 4' carpenter's level. Generally, when the bubbles are centered you're accurate to within 1/32". But what happens if the object you're leveling is 30' long? That 1/32 of an inch begins to multiply as you move farther away from the level.

Rotating lasers on the other hand "broadcast" a plane of light over distance. The beam is at a constant elevation or vertical plane no matter if you're next to the laser or 100' away. But that's only one advantage. Here's an example:

In the interior industry where lasers are widely used, a contractor places a rotating laser in its vertical position so the beam sweeps across the ceiling, down the far wall and across the floor. From that single setup he or she can hang a wall bracket from the ceiling, the floor, and place the studs exactly vertically by themselves. The savings realized from using a laser in this instance is two-fold: first the setup time is reduced from traditional methods by at least 50% or more because the same reference is used for the floor, ceiling and everything in between. Second, a two person job was reduced to a single person, saving labor and freeing that extra person to work on another part of the job finishing the job faster.

This is just one example, but these types of scenarios can be attributed to lasers in many areas of construction. Here's a brief overview of construction laser types, how they are used, and the general advantage they have over previous methods:

Interior Lasers:
Using visible beams, Interior Lasers are used to hang ceiling grids, align and mount floor and ceiling brackets for walls, align studs, level and hang cabinets, and a host of other applications unique to the Interior construction industry. Interior lasers with slope capabilities can be used to "rake-in" or match angles in situations where settling or non-90° angles occur. Their visible beams replace the need for cumbersome bubble vials, ceiling string, and chalk lines that can get in the way and require time consuming setups.

General Construction Lasers:
Using infrared beams, GC lasers are short to medium range (500' to 1000' radius) lasers used for exterior applications. Setting concrete forms, checking grade on flat pads, checking depth of footers and trenches, and even providing elevation indication for laser receivers mounted on excavators, backhoes, and the like are common applications for these lasers. Because the beams are invisible, these lasers use a receiver mounted on a grade rod to detect the beam. The receivers emit audible signals indicating where the beam is in reference to grade. These lasers provide a continuous and reliable elevation reference over a large area, yet they are passive. In other works, there's nothing to avoid or watch out for when construction equipment or personnel are working throughout the site, unlike stakes, strings, and reference laths. They also provide a large measure of safety in trenching applications by removing the necessity for the grade checker to be in the trench.

Slope/Machine Control Lasers:
Perhaps the most advanced of all rotating construction lasers, Slope/Machine Control lasers use high power infrared or barely visible beam lasers that "broadcast" over long distances (1500' to 2500' or more) at extremely exacting slopes. Land leveling applications in the farming industry is a prime example. Extremely gentle slopes are required across long distances to promote irrigation water coverage while preventing soil erosion. But other applications such as road and runway construction that require slope for rain drainage, long trenching jobs requiring a constant fall for the pipes, and large sites where multiple machines are operating off the same laser reference are also examples of the broad application of these lasers. GC lasers have all but eliminated the use of transits and other optical instruments that were used to verify grade during the construction process previous to the introduction of lasers.

Pipe Lasers:
One of the earliest application of lasers in the construction industry occurred in the pipe laying market. Unlike the lasers in the previous categories, Pipe Lasers emit a stationary (non-rotating) beam of circular, visible laser light. Underground alignment is accomplished by placing the pipe laser in the manhole with the beam "broadcasting" at the designated line and slope down the trench. A target is placed inside of the far end of the pipe section being placed and is positioned so the beam strikes the center of the target. Doing this section after section, the pipe sections provide a constant fall from the manhole (or starting point) to the destination. There are also "over-the-top" methods used that involve projecting the laser beam over the top of the pipe and "plunging" the beam down to the pipe using a Theodolite. Previous to laser technology, there were several methods employed to align the pipes including "batter boards", "drop" strings (a plumb bob type system) as well as other equally cumbersome methods.

Almost without exception, these markets have realized tremendous advantages in efficiency, accuracy, and safety through the use of laser technology. But that's not where the story ends. Laser technology continues to develop and evolve on a daily basis.