Disto D2:

Disto laser distance measurement 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"