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

Area of Science:

• Materials Science
• Optical Engineering
• Solid State Physics

Background:

• Accurate thermal expansion data is critical for designing optical systems that operate across a range of temperatures.
• Understanding material behavior under thermal stress prevents optical element failure and performance degradation.

Purpose of the Study:

• To experimentally determine the linear thermal expansion coefficients for eight key optical materials.
• To provide essential data for engineers designing optical systems for variable temperature environments.
• To characterize the anisotropic thermal expansion of crystalline magnesium fluoride, KDP, and lithium niobate.

Main Methods:

• Measurements were conducted using interferometric techniques over a temperature range from 60 K to room temperature (approx. 295 K).
• Linear thermal expansion coefficients were determined for samples including Polytran KCl, Polytran CaF2, CVD ZnS, CVD ZnSe, single-crystal and polycrystalline Ge, crystalline MgF2, KDP, and LiNbO3.
• For anisotropic crystals (MgF2, KDP, LiNbO3), expansion was measured parallel and perpendicular to the c-axis.

Main Results:

• Reported coefficients of linear thermal expansion for all eight materials within the specified temperature range.
• Detailed data for both isotropic and anisotropic materials, including directional expansion for the latter.
• The dataset provides a comprehensive resource for thermal management in optical applications.

Conclusions:

• The presented thermal expansion data is vital for the precise design and reliable operation of optical components in diverse thermal conditions.
• This research contributes fundamental material property data essential for advancements in optical engineering and materials science.
• The findings enable better prediction of dimensional changes in optical elements, improving system stability and longevity.