Long-term dimensional stability of a line scale made of low thermal expansion ceramic NEXCERA

Abstract

Length measurement was carried out on line scales made of the ultralow-expansion ceramic NEXCERA™ and synthetic quartz for 13 months. 550 mm long precision line scales made of the two materials were manufactured and their changes in length were measured over the same period, using a high-precision laser-interferometric line scale calibration system. NEXCERA was used to evaluate its long-term dimensional stability. Synthetic quartz was used because of its long-term stability to ensure the stability of the long-term length measurement, including the line scale calibration system and measurement procedure. The long-term stabilities of relative length expressed in terms of 2σ over 13 months were 1.1 ± 1.1 × 10−8 for NEXCERA and 4.2 ± 6.3 × 10−8 for synthetic quartz. The experimental results were within the estimated measurement error. No significant secular change in length was observed for the line scale made of NEXCERA.