Large Bondspot RTV Adhesion for NFIRAOS OAPs

The Narrow Field Infrared Adaptive Optics System (NFIRAOS) within the Thirty Meter Telescope (TMT) will unlock new potential for ground-based astronomy. This subsystem is a series of optics that correct for atmospheric turbulence seen in the Infrared wavelength. One of the critical challenges in the NFIRAOS system is the ability to operate at -30 degrees Celsius. The use of RTV (Room Temperature Vulcanizing) silicone as an adhesive allows a more flexible bond between the optic and its mount. This material is capable of withstanding temperature changes without losing bond strength. Additionally, the large Off Axis Parabola (OAP) mirrors provide a unique technical challenge in their mounting configurations. The optics have with a mass of 90 kilograms and must be mounted able to withstand a 50-degree temperature differential from their ambient temperature bonding. This paper builds of initial conceptual and prototyping work done by ABB and provides the next steps scaling towards a final design of large RTV bondspot optical mounting. Through a combination of simulations, iterative prototyping, room temperature and operational temperature stress testing, a final design proposal is presented backed by statistical and in-house life cycle testing methods. The findings in this work have applications as the industry moves towards mounting larger optics in increasingly challenging environments.