Infrared optical element mounting techniques for wide temperature ranges.

Area of Science:

• Optical Engineering
• Materials Science
• Aerospace Engineering

Background:

• Spaceborne interferometers require robust optical mounting systems capable of withstanding extreme temperature fluctuations (-120°C to +150°C).
• Standard mounting solutions often struggle to balance the conflicting demands of mechanical stiffness and stress mitigation for sensitive infrared optics.

Purpose of the Study:

• To develop and optimize a novel mounting system for infrared optics in spaceborne interferometers.
• To ensure mechanical stability and prevent stress-induced damage to optics across a wide operational temperature range.
• To meet the stringent stiffness requirements (natural frequencies > 200 Hz) for space missions.

Main Methods:

• Designed an aluminum alloy frame with integrated mechanical compliance to accommodate differential thermal expansion.
• Incorporated thermal adapters with specific thermomechanical properties between the metallic structure and the infrared optics.
• Analyzed and compensated for thermoelastic and acceleration-induced stresses on the optical components.
• Validated the system's performance using a case study of a miniaturized Fourier transform infrared spectrometer interferometer.

Main Results:

• The optimized mounting system effectively compensates for the coefficient of thermal expansion mismatch between optics and holder.
• High stiffness is achieved, meeting the natural frequency requirements (> 200 Hz) essential for space applications.
• Reduced interface stresses on mechanically sensitive infrared materials were observed under both thermal and acceleration loads.
• The system successfully balances stiffness and stress-free mounting requirements over the specified wide temperature range.

Conclusions:

• The proposed mounting system offers a viable solution for reliably mounting infrared optics in demanding spaceborne environments.
• The design demonstrates the successful integration of mechanical compliance and stiffness for thermal management and operational stability.
• This approach is crucial for enhancing the longevity and performance of optical instruments in future space missions, particularly for Fourier transform infrared spectrometers.