ISO 16331-1:2017

ISO 16331-1:2017 pdf free.Optics and optical instruments一 Laboratory procedures for testing
surveying and construction instruments一Performance of handheld laser distance meters.
5 General information
5.1 General
The maximum measurement range on typical targets (info and examples, see Annex F) and the uncertainty of measurements provided by handheld laser distance meters are influenced by the following factors.
5.2 Target reflectivity
The higher the target reflectivity, the better the signal to noise ratio at the receiver; therefore better measurement performance is achievable. For more details, refer to Annex F.
As handheld laser distance meters are used on construction sites and for indoor applications, typical targets are painted walls, bricks, concrete, wood, and similar targets. Special attention has to be paid to the effect of penetration of the laser into certain materials, e.g. white marble.
5.3 Background illumination
Background light in indoor applications is typically below 3 klx and therefore negligible. However, in outdoor applications, the sunlight reflected by the target might reach an illuminance of up to 100 klx and might cause a degradation of the signal to noise ratio and therefore, a poorer performance of the instrument.
5.4 Temperature of key components
The temperature of the laser system and of the receiver system has an influence on the uncertainty of distance measurement. Most of these instruments have a built-in temperature compensation system to minimize this kind of influence.
5.5 Atmospheric influence
The maximum range and the accuracy of laser distance meters are influenced by meteorological conditions at the moment of the measurements being taken. These conditions include variations in air temperature, air pressure and humidity of the air. Distances calculated by handheld laser distance meters are based on predefined meteorological conditions. To achieve accurate measurements, in particular at long distances, these meteorological variables in the distance calculation shall be determined and the measured distance shall be corrected accordingly if the device under test offers this possibility.
5.6 Measurement resolution
The measurement resolution of a measurement instrument shall be at least two times better than the specified accuracy. For very accurate measurements, like in a calibration situation, a laser distance meter shall offer a unit setting which allows a measurement resolution that is at least five times better than the specified accuracy.
5.7 Average deviation and uncertainty of measurement
The typical user of handheld laser distance meters wants to take only one single measurement and wants to rely on the specified maximum tolerances. Therefore, it is the value of the combined and expanded uncertainty of a single measurement that the user wants to see below the tolerance limits.
Handheld laser distance meters are often specified up to ranges extending the practical dimensions of typical mechanical test benches of reference measurement systems in laboratories. In this case, the length of the bench determines the maximum distance investigated for the accuracy compliance test (see 6.3). In this clause, a test procedure is presented to determine compliance with range specifications for this scenario. Similar to the test procedure for determining the compliance with accuracy specifications, the compliance with range specifications is also tested with favourable conditions and with unfavourable conditions. In case of unfavourable conditions, background illumination has the biggest influence by far. Therefore, the test procedure focuses on this effect.ISO 16331-1 pdf download.

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