# Method for Accuracy Assessment of the Length Measurement Unit of Laser Tracking Systems
## 4 Discussion
\begin{table}
\begin{tabular}{c c c c} \hline \hline
**Uncertainty** & \multicolumn{3}{c}{**Measured Distance**} \\ \cline{2-4}
**Estimation Method** & **100** & **500** & **900** \\ \hline Type A & 0.0004 & 0.0005 & 0.0009 \\ Simulation & 0.0002 & 0.0003 & 0.0005 \\ \hline \hline \end{tabular}
\end{table} 
Table 3: The uncertainties obtained with simulation and on the basis of ball-bar measurements. All values given in mm. Funding: This research was funded by the National Science Centre, Poland, grant number 2017/27/N/ST8/03063. Institutional Review Board Statement: Not applicable. Informed Consent Statement: Not applicable. Data Availability Statement: Not applicable. Conflicts of Interest: The authors declare no conflict of interest. References  
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