Laser distance meters (LDM) provides you with various measuring techniques for the precise measurement of distances of up to three kilometers.
A Laser Distance Meter sends a pulse of laser light to the target and measures the time it takes for the reflection to return. For distances up to 30m, the accuracy is 3mm. On-board processing allows the device to add, subtract, and calculate areas and volumes and to triangulate. You can measure distances at a distance. Compared with a good, old-fashioned tape there’s no contest. A Laser Distance Meter wins on every count: speed, accuracy, safety, versatility, convenience and functionality.
Basic Principles
A Laser Distance Meter sends out a finely focused pulse of light to the target and detects the reflection. The meter measures the time between those two events, and converts this to a distance. The formula is simple: Distance = Ä (Speed x Time). However the speed of light is 300,000 km per second, so to resolve differences of (say) 1 cm, the meter must measure time intervals of the order of billionths of a second. But don’t worry – the technology is well established and reliable. A laser distance meter can measure distances of up to 30m with an accuracy of É3mm. An Ultrasonic Distance Meter works on a similar principle, but instead of light it uses sound with a pitch too high for the human ear to hear. The speed of sound is only about ⅓ of a km per second, so the time measurement is easier, but there are other issues, as we shall see below.
These laser sensors use laser light (pulsed or continuously modulated) to measure geometric distances, heights, lengths, levels and positions in a non-contact process. To achieve this, all the components work together in a perfectly coordinated overall system. This system is made up of a laser, the transmitter and receiver optics, the sensitive photo diodes and sophisticated electronics and algorithms for time or phase measurement.
Drawing on various optoelectronic principles for measuring devices, such as time-of-flight, phase comparison and the pulse back-mixing method. These individual methods allow measurements accuracy to the millimeter, and measuring ranges up to several hundred meters.
Natural and manmade surfaces/objects
Using laser distance sensors or laser distance meter, you can measure on natural surfaces or reflectors and obtain fast and precise results. The laser distance meters operate using visible or invisible laser radiation and are rated as eye safe in compliance with laser class 1 or 2.
The devices are compact and locust allowing for various applications including construction, industrial both indoor and outdoor. All of the devices offer common standard interfaces, analog or digital data output, and parameterizable switching outputs.
Besides laser distance meters for industrial applications, there are also extremely compact and high-performance laser distance meters (“laser rangefinder” based on diode- or solid-state lasers) for deployment in defense and security technology.
A Laser Distance Meter is accurate to within a few millimeters, certainly equaling a tape for larger distances, and the line is always dead straight; no bending or sagging. You have a choice of units, and there is no risk of misreading, as with the intermediate marks on a tape. The Laser Distance Meter is much faster; point, click, and you have the result in front of you on the display. The job is done in just a fraction of the time it would take to use a tape. You do not need to walk to and fro, or have a helper at the other end. What is more, you can use it with one hand, leaving the other free to hold your notebook. With a backlit display and the laser dot itself, you can use your Laser Distance Meter in relatively poor lighting conditions.
There is no need to wait until morning or to rig up lights. You do not have to access the far end of the measurement range or poke anything where it should not be poked; only the laser light has to do that. You do not have to worry about obstacles on the ground, or even large features such as pipes or cables. If there is a line of sight to your target, and it is within range, you can very quickly find out exactly how far away it is. For the same reason, you can measure upwards without climbing to a ceiling or to the top of a building. So, the Laser Distance Meter brings safety benefits as well. No more scrambling up ladders or over steep or wet surfaces to get a measurement. These safety and versatility benefits are particularly valuable in hazardous environments, and there will be occasions when you would not be able to do the job at all with a tape. Only a Laser Distance Meter will do.
Distance measurement with tilt sensors
With LDM, Measuring a distance is easy, just power on your LDM and aim at your target and press measure.   The inclination angle of the line of sight of the LDM from the horizontal line is always displayed on screen in real time as one changes position of LDM. So one can easily measure inclined distances at various vertical angles including precise horizontal lines (0o), vertical lines (90o) and at 45o inclinations. You can use this function also to check horizontality and verticality of the surfaces and lines.
Indirect distance measuring
Indirect distance measure can easily be achieved. You are only required to measure at least two distance measurements, one precisely horizontal and other to the top of the object by selecting Pythagoras measurement function of the LDM.
The height of a billboard can easily be measured with a simple 3 measurements, the first shot establishes the horizontal distance, while the 2nd and 3rd measurements establish the top and base angle of the billboard. Height is then calculated and instantly displayed on the screen.
Suppose you have to measure up for a cable run underneath a building. There is no line of sight between the start and end of the run; you have to walk around the corner. Obviously a complicated task with a tape, followed by some work on a calculator. However with your Laser Distance Meter you can measure two sides of a right-angled triangle, and it will work out the third with its built-in Pythagoras functionality. Similarly, you can get the height of a structure without even being next to it, just by measuring your distance from the base and from the top, and you can measure the width of a building by standing some distance away and taking measurements from there.
Something else that a tape simply cannot do is to work out an area from two length measurements, or a volume from three measurements. Answers in seconds without a notebook and calculator. Another feature intrinsic to a Laser Distance Meter is that it can measure continuously in situations where you would have to reposition a tape repeatedly. You can walk along, marking out a path that is (say) a certain minimum distance from a building. This is another bonus that has great value in hazardous environments.
There are many applications, such as to measure the width of a billboard, or to between one point with another point, which are separated by a river, or two inaccessible points, but you ask for a quick, accurate, and safe solution of measurement.  So simply take two distance measurements to one point and then move the LDM to take the measurement to the second point, the distance between these two points will automatically  be calculated and instantly displayed on the screen.
Area and volume measurements
Area calculations, measure width and length, then area enclosed is automatically calculated.
Volume calculations, measure length, width and height. The volume enclosed by the three measurements is then automatically calculated
Camera and point Finder: When you are taking measurements up to 30m or further, the laser spots can hardly be visible and it is impossible to measure distance accurately. But some LDMs including Mileseey P7 which are equipped with high resolution camera and zooming capabilities(4X zoom in P7) can easily locate the right target on the screen and then simply pressing measure button to record the distance. Some LDM can measure up to 100m just as conveniently as measuring 10m.
The measurement taken can be exported to your smart mobile device or laptop via Bluetooth. The drawing or plans can be prepared thereafter.
Why use a tape now!
Finally a good old tape measure may be simple and reliable, but it is limited. You will need to find someone to hold the other end and also need to raise hot-work permits, make risk assessments and method statements. A Laser Distance Meter is accurate and quick and requires only one person and one hand. It is easy to use and versatile. Laser Distance Meters have on-board processing enabling the device to triangulate and calculate; it knows Pythagoras. You can measure distances at a distance, add, subtract and calculate areas and volumes.
