Distance meters are sophisticated measuring devices designed to make highly accurate measurements of distance, and in many cases, other parameters. These small, handheld devices
offer a quick and convenient way for a single user to safely measure nearly anything from a few feet to a few hundred feet long. Simply point the meter at the target and press the
button—the exact distance will appear on the display without the need to crawl over obstacles dragging a measuring tape.
Distance meters can be used in numerous applications. Distance meters are ideal for contractors and engineers when laying out or building a project. They can also be of great use to
electrical and HVAC professionals for precisely measuring duct or cable runs. The ability of distance meters to measure height is useful for crane and lift applications. They are also
ideal for measuring fill levels and material height monitoring.
Distance Meter Technology
Most distance meters rely on laser technology to make measurements. Lasers are intensely focused beams of light, usually of a single frequency. They are very useful for measuring distances
as they travel through the atmosphere at fairly constant rates and can travel long distances before dispersing, allowing the laser to retain much of its original intensity when the light
reflects off the target.
Laser distance meters generally use one of two techniques to calculate distance. The time of flight method sends a pulse of light to the target and precisely measures the
amount of time for the light to reflect back to the meter. With this method the distance to the target equals the speed of light multiplied by the time it takes for the round trip between t
he meter and the target, divided by two. This method is highly reliable and accurate to about 3mm over a distance of 30 meters. The primary drawback of time of flight measurement is the sheer
speed of light. Since light travels at 300,000 kilometers per second, small differences in distance may have travel times that differ by only a few billionths of a second. While the technology
is capable of making these minute distinctions, it is less reliable for very short distances.
The phase shift method is another way to calculate distance with a laser. With this method, the laser emits light pulses at a specific wavelength and frequency. Runtime
differences between the internal reference path and external measurement path results in a phase shift of the reflected pulse of light. The phase difference between the reference signal
and measurement signal is proportional to the distance between instrument and target.
Alternatively, some distance meters use ultrasonic technology instead of lasers. While both methods use a similar measuring principle, ultrasonic uses focused beams of sound rather than
light. Though ultrasonic distance meters are less expensive and offer many of the same advantages as lasers, they cannot match the range and accuracy of lasers. Sound waves are far more
difficult to focus than light beams so they disperse much more quickly and are more prone to interference from other objects as they spread out. This limits the range of ultrasonic distance
meters to around 15 meters while laser distance meters are accurate to distances many times that. Ultrasonic distance meters also require a fairly large, smooth, flat surface as the target
which can be a serious limitation.
Though distance meters are primarily concerned with measuring straight line distances, most models are capable of complex calculations that greatly increase the versatility of the instrument.
Some of the advanced calculations found on distance meters include add/subtract, area measurements, and volume calculations. Another, very handy, calculation found in many meters is the
Pythagoras function which determines distance from two other measurements. Suppose it was necessary to measure a cable that runs underneath a building. Without a line of sight between the
start and end points, it would be difficult to measure. The Pythagoras function could calculate the distance based upon a measurement from the start point to a corner of the building and a
second measurement from the corner of the building to the end point. This same feature would also allow height measurements by measuring your distance to the top of the object and the bottom
of the object.
Things to Consider When Selecting a Distance Meter:
- What is the range required?
- How much accuracy is needed?
- Are any advanced calculations needed?
- Does it require IP or NEMA protection?
If you have any questions regarding distance meters please don't hesitate to speak with one of our engineers by e-mailing us at sales@instrumart.com or calling 1-800-884-4967.
