Do Rangefinders Work Through Windows

There is a boatload of reasons to begin using a rangefinder. Whether you’re shooting long-range or practicing on a golf course, being able to aim and hit the bullseye is the ultimate goal, and so you may need to employ the use of this device.

You may just be indoors wanting to measure the distance of an object through a closed window, and you’re wondering how efficient your findings might be because you have to measure straight through a glass barrier.

Can your rangefinder be accurate through your window? To answer this, we first have to understand what goes on when laser beams hit the glass.

Do Rangefinders Work Through Windows

What Happens When You Use A Laser Rangefinder Through A Window?

The primary aim of utilizing rangefinders is to obtain accurate distance measurements. This is unattainable when you measure through glass or a window.

The measurement results are not reliable and can not be documented.

The only way to circumvent this is by covering the window or glass with very special coatings. If this is not done, the window will cause back reflections which will make the distance measurements invalid.

In some cases, the special coatings might not make much difference.

Even with the presence of special coatings that can greatly minimize or prevent these back reflections, glass generally has a higher refractive index than air, and since the beam travels through air before hitting the glass, the beam may not hit its target.

You may want to measure the distance of an object in a vacuum chamber that is divided by a glass barrier.

This will further worsen the overall error in the measurement as the vacuum on one part of the glass has a refractive index different from that of air, or the glass that is used to separate the two vacuum chambers.

Do Rangefinders Work Through Windows Or Glass

As a result of the significant difference in the refractive index, there can be an equally significant error in the distance measurements.

Also, when the beam hits the glass, the beam no longer travels on a straight path and is knocked off course. This is referred to as the bending of the beam.

As a result of the bending away from the straight path from the position tracker to the target, the tracker’s angular measurements will also be affected.

As the beam continues to progress, the nature of its bend will continue to change.

For instance, as the beam enters the glass at a specified angle thereby losing both accuracy and validity, the nature of its bend will change. 

If the entire experiment aimed to measure the distance of an object in the other vacuum chamber, as the beam enters the vacuum, the bend of the beam will change again as it emerges from the glass into the second vacuum chamber making the entire endeavor filled with errors.

Can A Laser Rangefinder Measure Through A Window Accurately?

For the laser rangefinder to even get a reading close to being accurate at all, some parameters must be set just right, unless the beam will never reach its target.

These parameters include the frequency of the beam coming from the laser rangefinder and the angle at which the beam hits the window

Some experts believe that if you hit the window with visible laser beams, then you should have a near accurate reading.

However, if you decide to use an infrared laser on a window that has been coated against infrared rays, then the strength of the laser beam will be significantly diminished.

In the case of an ultraviolet laser, you will find out that glass becomes opaque when hit with beams at ultraviolet frequencies.


As you are now aware, the measurements obtained through glass are not reliable. While there are a few things you can do to increase the chances of the measurements being accurate, you must not record them as your major findings.

Many also believe that cheaper and older rangefinder models have the most difficulty in measuring through the glass.

More recent advanced models are equipped with sharper lenses and more powerful beams and as such can give you a more solid chance of getting an accurate result.

For instance, an experiment conducted with the modern Simmons LRF600 proved more favorable than with an older cheaper rangefinder, Leupold RX II.

The results obtained from both rangefinders after a series of tests showed that the Simmons rangefinder could get a better reading and perhaps closer to accuracy reading through the window than the Leupold rangefinder.

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