Measurement optimization of high accuracy check master based on interferometry method in National Standardization Agency of Indonesia: a preliminary study for measuring range of 10 mm to 400 mm

Abstract

High accuracy check master is a type of geometry gauge that often used to check the accuracy of Coordinate Measuring Machine (CMM) in the high-class metrological institutes and manufacturing industries. This type of geometry gauge is composed of several high-accuracy short gauge blocks and a large rod as its foundation. Conventionally, the measurement of high accuracy check master can be carried on by using measuring machine. Since the bench has limit up to 400 mm, the measurement of high accuracy check master more than 400 mm range is performed in two-step. Firstly, from nominal range of 10 mm to 400 mm and the other range by utilizing extension. In some cases, this measurement method has bigger expanded uncertainty value, i.e. more than 2 µm. Since the check master has important role to verify the accuracy of CMM, the quality of calibration system of high accuracy check master is required to be improved. This paper describes only to achieve high accuracy of measurement up to 400 mm. In the developed measuring system, the heterodyne laser interferometer is used as the reference. The optical configuration of laser is combined with the measuring machine as a moving part. In order to improve the accuracy of measurement, the refractive index of air and the temperature compensation are recalculated manually by Edlen’s formula and linear expansion equation, respectively. Using this method, the expanded uncertainty from calibration 400 mm high accuracy check master is less than 1 µm. The results had a good agreement to the measurement results from manufacturer with international certification, experimentally. In conclusion, this method can be applied to calibrate the high accuracy check master of 400 mm range.

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