Measurement Uncertainty Evaluation Using Monte Carlo Simulation for Newly Established Line Scale Calibration Facility at CSIR-NPLI

Abstract

High-precision line scales are probably the most common physical standards for length measurements. They are used as reference standards, transfer standards, direct length measurement devices and ordinary measures for adjustments in length measuring machines etc. Hence, in the current scenario, a robust and reliable line scale calibration infrastructure with high precision and flexibility is of indispensable need. Keeping this in view, an improved calibration facility for line scales, ranging from 300 to 1000 mm, has been established at CSIR-NPL India by combining coordinate measuring machines, vision metrology and displacement measuring laser interferometer. The present article describes line scale (400 mm) calibration setup, measurement procedure and measurement uncertainty evaluation. Here measurement uncertainty evaluation is carried out by using two different approaches, law of propagation of uncertainties (LPU/GUM) and Monte Carlo simulation. The measured mean values and expanded uncertainties obtained by using the above two approaches are found to be in good agreement.