Ultraslow strain rate measurement system for ice using a modified phase modulation homodyne interferometer

Abstract

The analysis of the flow behavior of the Antarctic ice sheet provides information on past climate changes of Earth. To understand the ice sheet flow behavior, the ice creep strain rate measurements with various stresses are important. In this study, an ice creep strain rate measurement system with an uncertainty of order less than 10−10 s−1 and a minimum measurement time of 10 min is developed. The ice specimen of interest is set in a low-constant-temperature room and cell, with a set-point temperature and maximum stability of −30 to −10 °C and ±20 mK or less, respectively. A modified phase modulation homodyne interferometer, the supporting material of which is ultralow-thermal-expansion glass, is combined with the system to measure the ice deformation with the resolution of nanometer scale or less. In this paper, the operational principle, instrumentation and experimental results are discussed.