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ISO-Norm for Range and Accuracy

By jrowles


The Leica DISTO defines a new benchmark!

The range and accuracy of laser distance meters depend on light conditions and reflectivity of the measuring target. For Leica Geosystems it is important that the instruments not only perform under perfect laboratory conditions, but above all under the kind of everyday working conditions encountered on construction sites. This is why, working together with external experts, the company have developed a standard by which laser distance meters can be tested and compared with each other.

With almost 200 years experience, Leica Geosystems is the pioneer in the development and production of modern measuring technology and inventor of the hand-held laser distance meter. As the leading company in the market, Leica Geosystems has committed itself to making measuring instruments with praxis-oriented specifications, so that when they are used on site, they always do what it says on the box. As far as accuracy and range are concerned, this actually means that the specified performances are met under practical working conditions and not just under those perfectly prepared in the laboratory.

Differing factors, such as the structure of the surface and the color of the measuring point, the strength of ambient light and the temperature at which a measurement is taken, have a very significant effect on the accuracy and the maximum range achieved. These factors have not previously been defined by a standard, each manufacturer has used its own definition. It has therefore become increasingly difficult for the customer to make a comparison between the large and growing number of laser distance meters on the market. However, misunderstandings or imprecise data can result in serious unreliability of measurements or even expensive errors.

The new ISO Standard 16331-1, to which Leica Geosystems has made a significant contribution, defines in detail how information concerning accuracy and range must be presented and describes the necessary measuring procedures. This renders specifications of laser distance meters capable of being tested by independent institutions, thus making direct comparisons possible.

 The ISO Standard 16331-1 takes the following measuring conditions into account:


   ISO Illustration DISTO        

Measurement under favorable conditions – conditions which often apply for interior use:

  • Weak ambient light (3 klux)
  • Measuring to white painted wall
  • Room temperature
  ISO Disto Illustration 2

Measurement under unfavorable conditions – conditions which often apply for exterior use:

  • Bright sunshine (30 klux)
  • Measuring to white painted wall
  • Total operating temperature range
   ISO Disto Illustration 3

Other measuring conditions can also be specified, for example:

  • Measuring to a defined target plate 
  • Measuring to unfavorable measuring points with strong or weak 

A customer who purchases a laser distance meter which conforms to the ISO standard can arrive at reliable conclusions with respect to the maximum range and accuracy achievable under defined measuring conditions. This is crucial for assessing the advantages for everyday use on the construction site.