For this report dot center positions (x, y) are measured in the calibration target as shown in the below:
Ø pattern size: 20x10mm
Ø array size: 11x6
Ø dot spacing: 2.0mm
Ø dot diameter: 1.0mm
Ø type: chrome-on-glass
Ø OMM machine used: a Hexagon OMM machine with uncertainty Exy= ±(0.6+L/900) um (Laboratory temerature 20℃, humidity 49%)
Ø OMM measuring 3rd party is accredited in accordance with ISO/IEC 17025:2005 General Requirement for the competence of Testing and Calibration Laboratories
Figure 1. Ideal location of target
Figure 2. Measure result values of circle centers
For most measurement results, the measured (x, y) positions may generally have a inclination or eccentricity effect regarding its ideal positions. The original (x, y) results are transformed by a best-fit 2D rigid transformation, which will not change relative position of all points, towards their ideal (x, y) value. After this transformation, the inclination and eccentricity effect of measured value can be eliminated.
The error of every point is analyzed by calculating distance between ideal (x, y) location and actual (x, y) location. The result is shown in Figure 3.
Figure 3. Positioning error of measured calibration plate
In order to have a better understanding, the error vectors of all points are also presented in Figure 4. The error vector is pointing from a point’s ideal location to its actual location. In order to have a better visualization, all the vector are enlarged with a scale of 1844. As shown in Figure 4, the maximum error is marked in red circle. The maximum error of this plate is 0.81um, so it is enlarged to 1.5mm in below figure.
Figure 4. Vector error of all points
Conclusion:
As you can see in Figure 3, the maximum error of the whole plate is 0.81um. All feature points have a high accuracy of < ±1um. You can archive similar results of your optical measurement system by using our precise calibration targets.
