A novel method to calibrate standard angle gauge blocks

Abstract

Artefact standards, viz. polygons, angle gauges and indexed rotary tables, realize the geometric plane angle. The construction of the standard angle gauges restricts the pitch angle calibration using the closure technique. The angle gauges are traditionally calibrated using an autocollimator with an indexed rotary table. The positional errors in the angular scale of the rotary stage affect the measurement accuracy.A novel technique is devised to extend the benefit of the closure and the reversal techniques to calibrate the angle gauges. Eleven measurements are made on three angle gauge blocks, one reference angle block, and two angle stacks. These measurements are modelled using a set of equations. The pitch angle of the angle gauges is found by solving these equations. The uncertainty of angle gauge measurement is estimated as 0.32″. The proposed method is experimentally validated. The analysis of results ensured the elimination of the influence of the reference-indexed rotary table.