Following the selection of an appropriate measurement product it is usually prudent to perform acceptance tests to familiarise the user with the product and to establish a performance baseline. The complexity of acceptance tests can vary considerably from simple tests against a traceable measurement standard or the development of testing methods where none exist. OMC are able to deliver independence and rigour to the testing procedures where companies may not have the time, equipment, or background knowledge to design such tests themselves.

A customer required to measure the distance to a surface at an angle of 10 to 30 degrees with a range of 50 mm and a stand-off of 100 mm. An optical triangulation probe using a PSD sensor was chosen. To analyse the performance of this instrument the sensor was set up on a linear movement and a target was placed at an appropriate distance where the angle of incidence could be changed. An interferometer was also used to measure the distance to the target. A series of experiments was performed where the distances measured by both the interferometer and optical triangulation probe were compared. The results of this experiment are illustrated in the following figure

 Graph of the difference between the interferometer and the optical triangulation probe

The performance of the sensor was found to be within the manufacturers specification but the nature of the error profile could have given a consistent bias if it had not been understood and appropriate measures taken.