An apparatus has been designed and constructed for measuring the coefficient of linear thermal expansion in the 30–250°C temperature range for samples as small as 13 mm in length and 6 mm in diameter. Similarities between this apparatus and one previously built for measurements from room temperature down to 10 K are reviewed; important modifications appropriate to the high temperature range are discussed in detail. Measurements were made at 25°C intervals on two infrared-transmitting optical materials: polycrystalline cadmium sulfide (Eastman Kodak Co.) and chalcogenide glass 20, composition Ge33Se55As12 (Texas Instruments, Inc.). Measurements were also made on a sample of Corning crown glass 8263; the results are compared with Corning data. Finally, it is shown that the thermal expansion coefficients determined with this high temperature apparatus are compatible with those obtained with the above-mentioned low temperature device.
© 1972 Optical Society of America
Original Manuscript: September 3, 1971
Published: April 1, 1972
John F. Ebersole, Stanley S. Ballard, and James Steve Browder, "Apparatus for Measuring the Thermal Expansion of Optical Materials from 30°C to 250°C," Appl. Opt. 11, 844-848 (1972)