How do laser tape measures work

How Laser Tape Measures Work.

Measuring distances can be a difficult task. Sometimes your tape measure is too short. Sometimes your tape sags too much. Sometimes you need someone to hold the other end of the tape.

And if you have a metal recoil tape, sometimes it recoils so fast it cuts your finger.

I know. It hurts.

And then there are all the errors that can be made whilst using a tape measure. Errors that make your measurements useless.

But measuring distances doesn’t need to difficult. You just need to use the right tool for the job. This is where you need a laser tape measure.

Laser Tape Measures are brilliant devices for measuring long distances accurately. They are so much more versatile than the standard tape measure. And they can be used by just one person on their own. No need to drag along your assistant. You just point and shoot. Easy, accurate measurements.


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But how do laser tape measures know what the distance is. From a beam of laser light. Stick around and hopefully by the end of this article you will understand how laser tape measures work.

Simple = Understanding.

Complicated = Lack of Understanding.

Having worked in a technical field (Construction Engineering and Surveying) for over two decades, I have noticed that colleagues would often say:

Oh, it’s simple.

Or.

This is very complicated.

These statements seem innocuous in themselves. But what people usually mean is that either they understand how something works or they don’t understand how it works.

Using a laser tape measure is a simple process. Point the laser tape measure, press a button and the distance is displayed on the screen.

How the laser tape measure works out that distance is the complicated part. But it doesn’t have to be. Hopefully I will explain how they work in a simple way that anyone can understand.

Leica Disto D2

How Laser Tape Measures Work.

Laser Tape Measures use a modulated laser beam to measure time. From this known time measurement, the laser tape measure can calculate the distance.

Laser Tape Measures are Electromagnetic Distance Measuring devices. This is more commonly known as an EDM. This is because light is an electromagnetic wave (Light can also be considered a particle to).

Light and radiation refer to the same physical phenomenon that is electromagnetic energy. We often feel the effects of this radiation (the electromagnetic wave) when we are outside on a sunny day.

Over the years we have learnt how to harness, produce, and concentrate this light energy into concentrated beams. Laser Beams.

We now treat “Laser” as a word, but really it is an acronym. LASER stands for Light Amplification by the Stimulated Emission of Radiation.

Lasers are very common these days. All the lasers that we have, produce a very concentrated beam of light that we can direct at our will. The Lasers that we use in laser tape measures are very useful as they do not suffer from light dispersal from the beam, like the light from a torch or flashlight would. Lasers allow us to have a very narrow concentrated beam.

This means that the laser beam can travel long distances. Importantly it also means that a lot of the laser beam can be reflected back off surfaces to the laser tape measure. The laser tape measure needs to receive enough laser light back so that it can make the distance calculation.

How does the Laser Tape Measure use the Laser Beam to Calculate Distance?

Now that we know that laser light can be returned to the laser tape measure from surfaces that we want to measure to, we can now use this laser light to calculate the distance. As the laser light from the laser tape measure travels at a constant speed we can use this to measure the time it takes for the laser light to travel from and back to the laser tape measure.

The time period for the laser light to travel from and to the laser tape measure is incredibly small. It takes just 330nanoseconds for the light to travel 100m.

In order to calculate the time for the light to travel from and to the laser tape measure, the laser light is modified. This is done by creating an impulse modulation to the electromagnetic wave (the laser light). This can be either by increasing and decreasing the intensity of the light or by adding a pulse to the light.

When the laser light has been uniquely modified the returning light can be compared against the outgoing light and the time between these modulated waves can be calculated. And from this time calculation the distance can be calculated.

Choosing the right laser tape measure.

Knowing how laser tape measures work you can now have an appreciation of how technical they are and how well they can measure distances. Choosing the right laser tape measure is important. Get it right and you have a trusty tool. Choose the wrong one and you will be forever cursing the day you bought it.

Buying the cheapest laser tape measure available is never a good plan. I have just explained the intricacies of how they measure distances. A laser tape measure is worthless if it is not accurate. You would be better off buying a traditional tape measure than buying the Atolla T201 laser tape measure. I did buy 3 cheap laser tape measures to see if they were any good.

My choice of laser tape measure would be the Leica Disto D510. This is the laser tape measure that replaced the Leica Disto A5 that I bought back in 2007, that I still have and use at certain times. I like the Leica Disto D510 because it is accurate and can measure up to 200m. The Leica Disto D510 is more suited to professionals who need to take lots of accurate measurements daily. Like myself who works on large buildings and infrastructure projects where accuracy is paramount.

If I wasn’t working on large scale projects, then my choice of laser tape measure would be different. I would either choose the Mileseey S2 or the Leica Disto D1 or even treat myself to the Leica Disto D2. Why would I choose these laser tape measures? I have used many Leica laser tape measures and Leica Total Stations over the years and know that they are accurate for taking measurements. I would also recommend the Mileseey S2 laser tape measure. I tested it against my Leica Disto some time ago to see if it was any good.

My choice of laser tape measures would be:

  • Leica Disto D510
  • Leica Disto D2
  • Leica Disto D1
  • Mileseey S2
Leica Disto D2
Leica Disto D2, a Good Buy?

Do Not Buy this Laser Tape Measure.

I have tested a lot of laser tape measures over the years and recently I tested 3 cheap laser tape measures. The worst laser tape measure of the three was the Attola T201. I would recommend that you do not buy the Attola T201.

Why Is The End Of A Tape Measure Lo...
Why Is The End Of A Tape Measure Loose

I found that the Attola T201 had the worst accuracy of the 3 models tested. But what was more disappointing was the range. No matter what I tried I could not achieve the quoted range of the Attola T201. The maximum distance that I could achieve was woefully short of the 60m range claimed.

Measuring Distances can be Frustrating.

Measuring distances can be frustrating. But it doesn’t have to be. Choosing the right tape measure is key to taking accurate measurements. Traditional tape measures are straightforward to use and understand. And you should now know how laser tape measures work.

Taking accurate measurements doesn’t need to be difficult or frustrating or painful. You just need the right tool for the job.


Related Articles

5 of the Best Laser Tape Measures Available.

Are Cheap Laser Tape Measures any Good?

Review of the Leica Disto D2

Beginners guide to laser tape measures

Review of the Mileseey S2 laser tape measure

The purpose and importance of laser tape measures

Is a laser tape measure worth it?

How to get accurate linear measurements

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