High Precision Optical Strain Measurements at High Pressures
- Murli H. Manghnani and
- Yasuhiko Syono
Published Online: 21 MAR 2013
Copyright © 1987 by Terra Scientific Publishing Company (TERRAPUB), Tokyo.
High-Pressure Research in Mineral Physics: A Volume in Honor of Syun-iti Akimoto
How to Cite
Meade, C. and Jeanloz, R. (1987) High Precision Optical Strain Measurements at High Pressures, in High-Pressure Research in Mineral Physics: A Volume in Honor of Syun-iti Akimoto (eds M. H. Manghnani and Y. Syono), American Geophysical Union, Washington, D. C.. doi: 10.1029/GM039p0041
- Published Online: 21 MAR 2013
- Published Print: 1 JAN 1987
Print ISBN: 9780875900667
Online ISBN: 9781118664124
- Mineralogy and Crystal Chemistry;
- Phase transformations;
- High Pressure-High Temperature Research
We have used a high-resolution video image-shearing system to carry out the first direct measurement of the hydrostatic compression of glass in the diamond cell. Our work is based on a new optical technique for making precise length determinations. From calibration measurements and the diffraction theory of optical imaging we find that our system has the highest precision when measuring the spacing between lines that are thinner than the formal resolution of our objective lens (∼1.5 μm). By depositing a thin chromium emulsion of this pattern on the glass samples, we can measure sample lengths with an uncertainty of ±0.010 μm. For typical dimensions of diamond-cell samples (∼100 μm), this corresponds to measuring linear strains (δl/l o) to a precision of 10−4. Our data for fused silica and a Ca-Mg-Na glass, collected at room temperature to about 10 GPa, yield zero pressure bulk moduli (K o) of 37.0±5.5 and 35.5±3.7 GPa respectively. These values, and our finding that the pressure derivative of the bulk modulus is negative in both cases, are in good agreement with previous ultrasonic measurements.