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.

Early study on the application of Nexcera ultra low thermal expansion ceramic to space telescopes

“…NEXCERA has a high specific stiffness, extremely low coefficient of thermal expansion (CTE) and excellent long term stability. In the previous paper, the long term dimensional stability of NEXCERA was reported as 0.01 ± 0.01 ppm over 13 months [1]. The excellent polishing characteristics and new development of material composition suitable for mirror applications were also reported in a recent paper.…”

“…NEXCERA MATERIAL PROPERTIES Ultra low thermal expansion ceramic NEXCERA is a cordierite (2MgO-2Al 2 O 3 -5SiO 2 ) based ceramic and has advanced material properties to meet severe requirements of space applications. Its key properties are a high specific stiffness (140 GPa / 2.55 g/cm 3 ) [2] and high long term stability (0.01 ppm / 13 months) [1] combined with an extremely low CTE (< 0.03 ppm/K) at room temperature [2]. Its high stability against thermal disturbance and secular change allow it to be applied to optical components in earth orbiting satellites.…”

Characterization of the long-term dimensional stability of a NEXCERA block using the optical resonator technique

“…The error of our NEXCERA drift rate measurement is approximately 0.01 × 10 −8 yr −1 , 50 times lower compared to the measurement in ref. [14]. To ensure that the long-term frequency drift measurement was not affected by the quality of the optical contacts, we tested them visually and mechanically after completion of the measurements.…”

“…The first characterization of the dimensional stability of NEXCERA was recently reported by Takahashi [14]. Length measurements of line scales made from NEXCERA showed that the ceramic has good long-term dimensional stability.…”

A simplified cryogenic optical resonator apparatus providing ultra-low frequency drift

“…Ultra-low-expansion glass (ULE) is today the most common material for use at or near room temperature. Another promising material is the ceramic Nexcera [12][13][14] . However, the Brownian motion imposes a fundamental limitation to their length stability 15 .…”