Getting real about lasers

Back in the day, lasers either meant Buck Rogers and all things in the future, or the lasers on the dance floor as you boogied the night away. Now they are a hand-held measuring tool and a cat toy – how times have changed.

The term “laser” originated as an acronym for light amplification by stimulated emission of radiation. Lasers are all around us and have many important applications. They are used in consumer devices such as optical disk drives, laser printers, and barcode scanners. Lasers are used in fibre optics. They are used on construction sites to measure distances and elevations, in medicine for surgery and various skin treatments and in industry for cutting and welding materials. They are used in military and law enforcement devices for marking targets and measuring range and speed. Laser lighting displays use lasers as an entertainment medium. In other words, we encounter lasers in our everyday life, many times without even knowing.

The lasers that we are going to concern ourselves with today are the ones that are used on a construction site. Construction lasers can have a red beam, a green beam or be totally invisible to the naked eye, but please note that all these just can’t be visible on a jobsite as that would be far too dangerous to use.

Originally, laser beams were created by using a gas-filled vacuum tube, which turned out to be very expensive, susceptible to vibration and easily damaged. They are now created by using a lasing diode, which is much more durable and far less expensive to manufacture. A construction laser is really very simple as it uses a lasing diode to create a beam, a compensator that allows the beam to be adjusted to the horizontal and a motor, which then spins the beam to cover the entire construction site. Once the height of this beam is known then elevations all over the site can be calculated. Also very useful is the ability to use as many sensors as needed to get the job done quicker. When buying a construction laser, the price can be anywhere from $500 to $5,000 as it really depends on what you need regarding features, durability, accuracy, slope capabilities and range.

Most of the lasers on the market today use electronic levelling, which means that after quickly setting up the laser to approximate level and turning it on there are no foot screws to adjust or bubbles to look at, or to become unadjusted.

Today we will talk about the electronic levelling lasers. There are different types of lasers available, but it all breaks down to the following for outside lasers.

Horizontal lasers are usually called one-button lasers and can account for more than 90 per cent of the work on a job site. Just press one button and walk away as they level themselves, nice and simple.

Manual grade lasers are used where the occasional slope might be required, such as for small grading or pipe jobs. On these units you actually turn off the compensator and then manually (using the laser controls) slope the beam to the desired amount. Very useful, but care must be taken.

Single slope lasers are more advanced as now you can dial in a slope to three decimal places for high accuracy.

Dual slope lasers are as above but now with dual slopes. They are for very advanced applications, such as the levelling of large areas and fields where you would want the water to be drained to one corner, as in a cranberry field.

H/V lasers are lasers that can be used in either a horizontal or vertical mode. In the vertical mode you can check the alignment of a pipe or see just how vertical that wall is anyway. They are very versatile.

The accuracy on lasers used in the construction field is stated in fractions of an inch per 100 feet. A good laser will be plus/minus 1/16 inch per 100 feet while others are stated anywhere up to plus/minus ¼ inch or more. These less accurate ones should only be used on a smaller jobsite or maybe for landscaping. Just consider that if you are on a building site and you are out ¼ inch high on one side you will be ¼ inch down on the other side for ½ inch out on a small jobsite. This might be ok for certain jobs, but not at all accurate enough for commercial projects like warehouses and condominiums. Some lasers will only give the accuracy over 50 feet or less, so just extrapolate that to 100 feet to get the true number.

 Warranties are all over the map as manufacturers via for your attention.  One-year, two-year, three-year, four-year and up to five-year on factory defects are available, but make sure they are offered in your province.  I would drop any make offering warranties of one year, two years or none at all.

Think about how waterproof the instrument needs to be to last in the rain, especially out here on the west coast of Canada. Out here, I would not go any lower than an IP55 on the international rating scale. The first number (five out of seven) measures dustproofing and is not much of a concern in B.C. The last number (five) is for waterproofing. A rating of eight is underwater-proof, so a five should be the minimum you would look for. If there is no IP rating at all then politely decline the purchase. It will only cause you and your customer grief when they need it most.

Check to see if there is a service shop in your town or at least in your province.  And of course check and make sure that the laser has been checked and adjusted by the supplier prior to you buying it and putting it on your shelf for sale.

So many questions, so little time, so try to look at survey equipment that has been manufactured by companies that are known for survey equipment. Ask surveyors and engineers on jobsites what they use. They are one of the most important tools on the site.