Carbon–carbon silicon carbide (C/C–SiC) is a ceramic matrix composite combining low density with high stiffness, damage tolerance, and excellent thermal properties. A feature of this material is its low (0.1𝜇m/mK) and tunable coefficient of thermal expansion (CTE), making it highly suitable for precision structures that must remain dimensionally stable under varying thermal loads. This thesis investigates its applicability to a 100 mm diameter Cassegrain telescope structure as a candidate for space-based laser communication terminals. A parametric thermo-elastic finite element model was developed in COMSOL Multiphysics. Rigid body motions and surface form errors were quantified using a Zernike-polynomial-based Python post-processing pipeline, enabling evaluation of optical performance. Results show that by targeting a near-zero in-plane CTE, C/C–SiC can maintain deformations within acceptable limits, supporting its feasibility for lightweight and stable free-space optical communication
systems. Using an opto-thermo-mechanical workflow, the model couples radiative and conductive heat transfer with the structural response to assess wavefront stability under representative orbital thermal load cases. Within the evaluated steady-state cases, tuning the in-plane CTE to approximately 0.1–0.5 𝜇m/mK kept rigid-body motions and surface-form errors within a 𝜆/30 ≈ 50 nm RMS budget, leaving margin for other effects treated as out of scope. From a production perspective, however, current cleanliness and manufacturing-consistency challenges for large continuous-fiber C/C–SiC constrain near-term applicability to off-the-shelf terminals, suggesting more viable deployment in other use cases until maturity improves.

http://10.4121/e139a134-6bd2-4298-932d-975356efd964
Location of the models and post-processing scripts