Abstract

A three-terminal capacitance type dilatometer has been developed for investigating the thermal expansion of optical materials at low temperatures. The method is applicable when only small sample lengths (13 mm or less) are available. The thermal expansion coefficients of six polycrystalline materials (the Irtrans) and of one nonoxide glass have been determined in the range from room temperature down to about 60 K. Minute changes of the length of a sample produce a change of the spacing of a parallel plate capacitor with guard ring; the resulting change of capacitance is measured on a highly sensitive bridge. The expansion coefficients are then determined by relating the change of capacitance to the change of dimensions of the sample.

© 1969 Optical Society of America

Thermal Expansion Measurements on Four Optical Materials from Room Temperature to 10 K

James Steve Browder and Stanley S. Ballard
Appl. Opt. 11(4) 841-843 (1972)

Apparatus for Measuring the Thermal Expansion of Optical Materials from 30°C to 250°C

John F. Ebersole, Stanley S. Ballard, and James Steve Browder
Appl. Opt. 11(4) 844-848 (1972)

Measurements of the thermal expansion of six optical materials, from room temperature to 250°C

Stanley S. Ballard, Stephen E. Brown, and James Steve Browder
Appl. Opt. 17(7) 1152-1154 (1978)

Precision Thermal Expansion Measurements on Low Expansion Optical Materials

W. A. Plummer and H. E. Hagy
Appl. Opt. 7(5) 825-831 (1968)

Thermal expansion data for eight optical materials from 60 K to 300 K

James Steve Browder and Stanley S. Ballard
Appl. Opt. 16(12) 3214-3217 (1977)