Vertical metro-scopes using Abbe’s principle AVM are used for different dimensional measurements. The accuracy of their measurement is low compared to other available techniques used in the calibration of gauge blocks. This uncertainty can be improved through the use of laser interferometer system in combination with it. This paper describes the improvement, the results of the calibration of a set of gauge blocks and the uncertainty budget for such a calibration. The uncertainty of such calibration is estimated to be within ± (0.06+L/650) *m; L in mm; for gauge blocks less than 200 mm. An inter-comparison between the results of such improved AVM and the results obtained from one of the gauge block electronic comparators available on the market proved that the differences in the mean results are insignificant.