Long-term stability and temperature variability of Iris AO segmented MEMS deformable mirrors

TL;DR

This study evaluates the long-term stability and temperature effects on Iris AO segmented MEMS deformable mirrors, demonstrating minimal error increases over time and small temperature-induced deformations, supporting their reliability in precision applications.

Contribution

It provides empirical data on the stability and temperature variability of Iris AO DMs over nearly two years, highlighting their robustness for open-loop correction systems.

Findings

Small increase in positioning errors over 29 months (1.38-5.68 nm rms)

Errors due to temperature changes are less than 1.42 nm rms/°C

Segment deformation due to heating is ≤0.11 nm rms/°C

Abstract

Long-term stability of deformable mirrors (DM) is a critical performance requirement for instruments requiring open-loop corrections. The effects of temperature changes in the DM performance are equally critical for such instruments. This paper investigates the long-term stability of three different Iris AO PTT111 DMs that were calibrated at different times ranging from 13 months to nearly 29 months prior to subsequent testing. Performance testing showed that only a small increase in positioning errors occurred from the initial calibration date to the test dates. The increases in errors ranged from as little as 1.38 nm rms after 18 months to 5.68 nm rms after 29 months. The paper also studies the effects of small temperature changes, up to 6.2{\deg}C around room temperature. For three different arrays, the errors ranged from 0.62-1.42 nm rms/{\deg}C. Removing the effects of packaging shows that errors are $\le$0.50 nm rms/{\deg}C. Finally, measured data showed that individual segments deformed $\le$0.11 nm rms/{\deg}C when heated.