The Stress-Optical Coefficient of Glasses

JSGT 1945 V29 T111-T123

A knowledge of the stress-optical coefficient of glass is necessary in calculations of the internal stresses set up by the application of mechanical force. Earlier measurements are reviewed and the results of new investigations are described, based on two groups of glasses, namely, (1) a series in which CaO progressively replaces Na₂O on a molecular basis in a parent glass of the general formula 6SiO₂.(2−x)Na₂O.xCaO, (2) twelve commercial optical glasses containing varying percentages of PbO (seven glasses) and BaO (five glasses). The progressive replacement of soda by lime in the above parent glass resulted in a small but significant increase in the stress-optical coefficient. The results of the measurements on the lead oxide-containing optical glasses were in good agreement with the general results for similar glasses published by F. Pockels in 1902.

W. Balmforth & A. J. Holland