Disto laser distancemeter FAQ:

What does the displayed message E 255 mean?   The return signal is too weak, measuring times are too long. The measured distance must be more than 250mm. Use a target plate to reduce measuring times.     What does the displayed message E 256 mean?     The return signal is too strong. If using target plates, the white side should be used for measuring short distances.     What does the displayed message E 272 and E 288 mean?     Turn the instrument off and on again. If the messages continue to be displayed, the instrument has to be sent in for servicing, as there is an internal module error in the electronics.   Can data from Leica DISTO be transferred directly to AutoCAD?     Yes, a direct transfer is possible with out software DISTO online. But there is software that permits an indirect transfer of the data into CAD-Programs. More information is available in the internet under "third party software suppliers".     How accurate is Leica DISTO at 0.5m, 1m to 200m?     The measurement deviation for Leica DISTO devices is not directly proportional to the measured distance. Therefore the accuracy of a Leica DISTO remains constant until a range specified in the manual. After this range the accuracy will change by a value proportional to the distance which is also specified in the operation manual. In many cases a maximum measurement deviation will not be exceeded. E.g. the Leica DISTOD3 is having an accuracy of 1mm up to 10m. After this the deviation will increase by 0,025mm/m (so at 30m the accuracy will be 1,5mm). After 30m the deviation will increase by 0,1mm/m (at 100m the measurement deviation might be 8,5mm).   Please note that measurement conditions may have an influence on the accuracy. Read more about this in the FAQ for "typical accuracy". The tolerance is not proportional to the measured distance, it is the same over the entire distance. However, over long distances, additional errors of +/-5 ppm (parts per million) (+/-0.5mm/100m) come into play..     What is measuring accuracy?     Measuring accuracy is specified in accordance with ISO-recommendation ISO/R 1938-1971, with a statistical safety of 95% (2s, i.e. two-fold standard deviation). Typical measuring accuracy is based on average measuring conditions within the specified measurement range. It is not valid for special application functions and calculations, such as Pythagoras and is not valid in tracking mode (continuous tracking).       link: measuring accuracy   How can I monitor my measuring equipment on my own?     Monitoring of measuring equipment for Leica DISTO - users who perform the required monitoring themselves, in accordance with their quality management systems: Measure an easily accessible distance of 2 to 10 m with a distance measuring instrument approved by your national bureau of standards. Make 10 measurements over the same distance. Determine the deviation of your measurements from the actual distance and calculate the standard deviation from the results. Record the value and set the time for the next series of measurements. Repeat these check measurements regularly, especially before and after important measuring tasks. Mark the Leica DISTO with an inspected sticker and protocol the entire monitoring process. Your Leica DISTO meets the specified accuracy, if the standard deviation is equal to or less than the value stated as the typical standard deviation. A Leica DISTO checked on the test distance works with the specified accuracy over the entire specified measuring and temperature ranges.     Which measuring technology does Leica DISTO use?     The distance measurement with the Leica DISTO is based on the phase measurement principle. The laser diode emits light pulses with a defined wavelength and pulse repetition frequency.   Due to the runtime difference between the internal reference path and the external measurement path, the light pulses, reflected on a target and received from the Leica DISTO, have experienced a phase shift in relation to the light pulses received through the internal reference path. That phase difference between those two signals is proportional to the distance between instrument and target.   The receivers convert the optical signals into electronic signals and the analogue-digital-converters (ADC) of the micro controller convert them into digital signals.    The built in micro controller calculates the phase difference between the reference signal and the measurement signal. If the phase difference is higher than 360 degree, for example 410 degree, then the micro controller would calculate a distance corresponding to 50 degree. To avoid such an error the pulse repetition frequency of the laser light pulses has to be reduced and a second measurement, a so-called coarse frequency measurement, has to be executed. Depending on the specified measurement range of the instrument various coarse frequencies have to be used to calculate the correct distance.     Accuracy of the instrument:     The accuracy of a laser distance measurement instrument based on the phase measurement principle is depending on the precision of the crystal oscillator inclusive temperature compensation, the jitter compensation of the frequency synthesizer, the crosstalk between different signal paths, the signal to noise ratio of the received light and the time the signal is sampled into the micro controller.   Concerning the last point it is worth to mention that in case of the fine measurement (using the highest frequency) a shorter sampling time results into a higher measurement jitter of a few millimetres between various measurements on the same target. In case of a coarse measurement (using one of the lower frequencies) a shorter sampling time could result into a coarse measurement error of various hundreds of millimetres.   Therefore it has to be evaluated very carefully how to balance sampling time versus accuracy. For all possible measurement conditions concerning the distance to the target, the surface characteristics of the target and the background illumination, the sampling time has to be determined in such a way that on the one hand the measurement time is as short as possible and on the other hand a coarse measurement error is completely avoided. This means that under difficult measurement conditions a shorter measurement time leads to a higher risk for a measurement error.     Can I perform an indirect measurement (Pythagoras) while holding the instrument in my hand?     Yes, but be aware that the result is more of an estimate than an exact measurement. To obtain good results use a tripod. To keep the centre of rotation steady, we offer special adapter plates.     What accuracy of my Leica DISTO can I expect when using the functions for indirect measurements?   Some Leica DISTO devices are offering the possibility of measuring heights or widths using indirect measurement functions with Pythagoras theorem or with inclination sensor. Generally it is recommended to measure any height directly at the object by using simple distance measurement. If this is not possible because the object is not accessible or a high accuracy is not needed measurements can be also taken with the indirect measurement functions.   Measurement of areas for polygonal rooms?   You can measure the area of a polygonal room by taking it apart into triangles and rectangles. You have to split the layout of a room in triangles and rectangles which cover the whole area once. After this you can add all areas together and will get the total area of rooms with even complex layouts. At following link you will get a template with formulas where you can even transfer the data for the distances into the according cells. link: triangle calculate template   Can Leica DISTO send an analogue signal?    No. The only way is using a digital-to-analogue converter.     What about the measuring technology?     The distance measurement with the Leica DISTO is based on the phase measurement principle. The laser diode emits light pulses with a defined wavelength and pulse repetition frequency.   Due to the runtime difference between the internal reference path and the external measurement path, the light pulses, reflected on a target and received from the Leica DISTO, have experienced a phase shift in relation to the light pulses received through the internal reference path. That phase difference between those two signals is proportional to the distance between instrument and target.     How can I measure outdoors with a Leica DISTO?     In bad weather or at dawn it is not a problem, when the sun shines the laser dot may no longer be clearly discernable. For distances up to 15 m we recommend our laser protective glasses. Through the red glass the laser point can be seen more distinctly.     The more professional approach is our telescopic viewfinder with 4x magnification. Measurements of up to 200 m can be made. You don't have to see the laser dot, the cross hairs on the lens act as the aiming device.     What are favourable / unfavourable measuring conditions?     Favourable/average measuring conditions:   Materials with good reflecting characteristics, meaning they reflect the laser beam in a divergent (not mirrored!) manner   Laser dot is brighter than the ambient light   Betrieb Operating within the allowable temperature range (-10 degree + 50 degree C)     Unfavourable measuring conditions:   Highly reflective surfaces   Highly absorbing surfaces, such as wet or dark surfaces   Operating at the limits of the allowable temperature range   Not waiting for temperature calibration   Very intensive ambient light   Shimmering   For optical and safety reasons, do not measure against colourless liquids (water) or glass     DISTO Safety & Certificates:   Leica DISTO emits a visible class 2 beam according to:   IEC825-1: 1993 "Safety of laser equipment"   EN60825-1:1994 "Safety of   equipment" FDA 21CFR Ch.I 1040: 1988 (US Department of Health and Human Service, Code of Federal Regulations)

What is a laser distance meter?     A handheld device that uses a laser for measuring distances between two objects. The best models are accurate within (+/-) 1/16th inch (+/- 1.5mm) and have a range of up to 650 ft (200m). The original, and most popular laser distance meter is the Disto by Leica Geosystems.   How does a laser distance meter work?     The user aims a red laser dot at an object, such as a wall, pole, cabinet or board. The user then triggers the unit to measure and the distance to the red dot is displayed on the screen. Normally, the unit is placed where the user would hold a tape measure and the dot is aimed at the point to which the tape would be extended. Precision optics and laser physics are used to quickly and accurately determine the distance to the object.     The most accurate devices use the phase shift method. They are accurate within +/- 1/16th inch and have a range of up to 650 ft (200m). The most common of these is the Disto by Leica.        How does it differ from a range finder?     Laser range finders are generally used for longer distances and when accuracy is not as critical. They are commonly used for hunting, golf and forestry applications. They often use the time of flight method for determining distance. The measuring ranges vary, but can be as great as 1000 yards (910m) and typically have an accuracy of +/- 1 yard (0.91m) Bushnell, Leica, Nikon and Optonics are a few of the range finder manufacturers.        How does it differ from ultrasonic / sonar devices?     Sonar or ultrasonic devices with a laser pointer used only for aiming the device. They emit a sound wave and measure the time it takes for the sound to come back to the unit. They then calculate how far the sound travelled before it was reflected back. There is no guarantee that the sound was reflected from the same item at which the laser was pointed, thus often providing the user with false readings, especially in rooms with furniture or cabinets on the wall. The range on ultrasonic devices is normally limited to 50 feet (15m), they do not work well outdoors and they are normally accurate within +/- 6 inches (15.24cm) over a 50 feet (15m) range. They are useful in applications where accuracy is not required and there are no obstructions in the measuring environment.         Who uses laser measuring devices?     Common users are Contractors, Architects, Real Estate Agents, Stage Technicians, Painters, Plumbers, Surveyors, Estimators, A/C Installers, Window Installers, Window Covering Installers, Carpet Installers and Flooring Salesmen.        What are the advantages of a laser distance meter?     Time savings: It is normally much faster to turn the laser on, hold it against a wall, for example, aim at the opposite wall and presses the button than to extend a tape measure to the far wall take the reading, and retract the tape. This is true in small rooms, and even more so on larger areas. The more crowded the area being measured, whether with furniture, equipment, trees, etc, the greater the time savings. Typical measuring jobs can be completed in about 1/3 the time required to use a tape measure. Time savings increase as the distances get longer.     Accuracy: Laser devices measure the true, straight line distance between two points, without the bend or sag that commonly occurs in tape measures.     Prevention of Errors: It is much easier to read the digital display on a laser measuring device, which can be held in a convenient position, than to read a tape measure that needs to be held in the measuring position. Most laser devices allow the user to select the units of measure, eliminating the need for conversion of units, a common source of measurement error. Laser devices display the measured value, preventing the user from misreading the dash marks on a tape. One Person Can Take Most Measurements: Tape measures often require a 2nd person to hold the end of the tape. Lasers are simply aimed at a target, such as a wall, pole, door, stake or post.   Difficult to Reach Measurements: High ceiling measurements are as easy as setting the laser on the floor and aiming at the ceiling. Tall buildings, 2nd floor extensions, measurements across water, measurements in tight quarters, are all easier with a laser measuring device. Some models are able to triangulate measurements that are otherwise inaccessible.     Data Interface: Some lasers are capable of sending the measurements directly to a computer for further processing. The Disto A6 will transmit measured dimensions to Any Windows software using a Bluetooth data interface. Many software vendors are incorporating the ability to import measurements directly from the Disto A6 into their programs, including PowerCAD, ZipCad and others.        What different kinds of laser measuring devices are available?     Laser Distance Meters: The Disto brand by Leica is the market leader and has 5 models, the Disto D2, Disto D3, Disto A5, Disto A6 and Disto A8.        Laser Range Finders: These are handheld devices. Rangefinder manufacturers include Bushnell, Leica, Nikon and Optonics. A few of the applications include hunting, archery and golf. They generally measure a longer range than Laser distance meters; up to 1000 yards (910m), with accuracy to within +/- 1 yard (0.9m).     Laser Sensors: Laser sensors are commonly used in manufacturing, quality control, and processing applications. They are more appropriate for shorter ranges; from under an inch to several yards. But commonly laser sensors are much more accurate - in the thousandths of an inch.        Is there any change in the accuracy as the distance increases?     The tolerance does not improve at shorter distances. It is essentially the same over the entire range (up to 200m or 650 ft.) of distances being measured. However, at distances over 100m (300 ft), additional errors of +/-5 ppm (parts per million) (+/-0.5mm/100m) come into play.        What is a direct measurement?     A direct measurement is one where the operator positions the measuring device at one end of the object being measured and points the red laser dot to the other end of the object to obtain a measurement. Direct measurements are commonly used indoors to determine the width of a room. The user holds the base of the device against a wall, and aims to laser dot at the wall across the room. Direct measurements are very accurate. With the use of the addition and subtraction keys, and creative selection of targets, most objects can be measured using the direct method. For situations where it is difficult to use the direct method, some laser distance meters have an indirect measurement, or triangulation feature.       What is an indirect measurement (triangulation)?     Indirect measurements allow the user to measure objects that don't have easy targets. A common use of this feature is measuring the width of a house from the street. The easiest method requires the user to stand in front of the house, in line with (perpendicular to) one end of the wall being measured. The user takes one measurement to the far end of the wall, and a second measurement to the near end of the wall. Both measurements must be taken from exactly the same point. The length of the wall is calculated and shown on the display. This method is the first triangulation option on the Disto.     A more accurate method uses 3 measurements. The user is able to stand anywhere in front of the house, between the ends. The first measurement is taken to the left end, a second measurement is taken perpendicular to the house, directly in front of the user, and the third measurement is taken to the right end of the house. All three measurements must be taken from exactly the same point. The Disto calculates the length of the house. This is the second triangulation option on the Disto.     The third triangulation option on the Disto allows the user to measure the height of a second story window (or similar feature) from the ground. The user measures the distance to the top of the window, then to the bottom of the window, and then the distance they are standing away from the house. Again, all three measurements must be taken from exactly the same position. The Disto returns the height of the window.     To access these features, press the triangulation key on the disto. Toggle through to select the method preferred, and follow the prompts on the screen that shows the order and location of each measurement. Note: Indirect measurements are not as accurate as direct measurements, and the accuracy specs do not apply. Typical accuracy on a 40 feet (12m) indirect measurement, using proper methods is (+/-) 1 foot (0.3m). We recommend practicing indoors to hone your skills prior to using this method outdoors.        What models have the Indirect (Triangulation, Pythagorean) capability?     The Disto D3, Disto A5, Disto A6, and Disto A8 have the triangulation features.      How does the indirect (also called Triangulation or Pythagorean) methods work?     Laser measuring devices use a process called triangulation to calculate indirect measurements. Triangulation involves measuring two sides of a right triangle and mathematically determining the missing (3rd) side using the Pythagorean Theorem - "the sum of the squares of the two sides (shortest length) of a right triangle is equal to the square of the hypotenuse (longest side)." For example, if you were able to position yourself at the southwest corner of a house (facing north) so that you can see the complete south side of the house (off to your right) and also at a position perfectly in line with the west side of the house, you have created a right triangle. One leg of the right triangle is the distance from you to the southwest corner of the house. The diagonal measurement from you to the southeast corner of the house is the hypotenuse (longest side). The third side (missing length) is the distance from the southwest corner to the southeast corner of the house. With indirect measurements, the Disto takes these two measurements and mathematically determines the missing side for you; no mathematical computations are required of the operator. In this example, if the first measurement taken for the perpendicular distance from you to the southwest corner was 60 feet and the second measurement from you to the southeast corner is 100 feet, you could use the Pythagorean theorem to determine the missing leg. To mathematically compute this, you would do the following:     (60 x 60) + (Missing length x Missing length) = (100 x 100)   3,600 + (Missing length x Missing length) = 10,000   3,600 -3,600 + (Missing length x Missing length) = 10,000 -3600 (subtract 3600 from both sides)   (Missing length x Missing length) = 6,400   Missing length = 80 ft (square root of 6,400)     Which Leica DISTOs offer an interface for communicating with a computer?     The Leica DISTO A6 utilizes BLUETOOTH technology for communication with Bluetooth compatible computers and PDAs. Measurements and directions (up, down, left right, etc.) can be transferred wirelessly.