FAQ: Measuring accuracy

This section contains questions and answers concerning measuring accuracy.

I cannot obtain the desired measuring accuracy, some of the measurements are unstable. What can I do to improve measuring accuracy?

Please note: The longer the measurement time, the higher the measuring accuracy.

  • Increase the measurement time of the GEPARD receiver (from 0.5s to 2s or even 5s).
  • Carry out an analysis of the surroundings: This function of the WIN-GEPARD software helps to determine the measuring accuracy that can be obtained under the current conditions.
  • Use the WIN-GEPARD's adaptive measuring method. It may be necessary to slightly adjust the tolerances.
  • Carry out identical measurement sequences several times and evaluate the results using the statistics module.
  • Gather any number of measurements for individual measuring points in the positioning module (long measurement time: e.g. 5s). WIN-GEPARD outputs the average of the measured values as Xquer and Yquer.
    You can also obtain the Xquer/Yquer values in a straightness measurement and export them to an Excel table. To do so, use the regression line function to subsequently record the straightness graph.

Measurement setup: Make sure the GEPARD measurement system is set up in a mechanically stable and reproductive way. The GEPARD laser transmitter needs to be mechanically coupled with the GEPARD receiver, i.e. firmly mounted to the test object, to ensure that the position remains stable during measurement.

Environment: Check your environment for possible sources of interference such as heavily vibrating machine tools, heavy fork-lift trucks in motion, transmission of vibrations to your shop floor originating from nearby roads or railway tracks etc. Air current caused by alternating temperatures (air conditioning systems, heating systems etc.) are another source of interference which greatly impact accuracy. The GEPARD uses a laser beam for reference, i.e. light, and light reacts to refraction. Different ambient temperatures cause air current resulting in various atmospheric layers, which in turn cause refraction along the edges of the individual layers (air flicker). Since the GEPARD measuring device measures in the micrometre range this air flicker is recorded as a measuring error. The only corrective measure is to homogenise the environment: The temperature should be constant, and no draught or jet-like, highly homogenised air current (fan) should flow over the test object.

Please bear in mind that our user guide contains lots of useful information on this topic.