Evaluation of the potentialities of the roughness characterization via replica approach

In the development of next generation telescopes, the quality of optical surfaces in terms of roughness is an important parameter for determining their performance and it is constantly monitored during the manufacturing process. While portable instruments are commonly employed for on-surface monitoring, their effectiveness diminishes in case of large optics with complex geometry and/or thin substrate. In such a scenario, the replica approach emerges as a highly efficient alternative, involving the acquisition of imprints on surfaces with silicone-based replication materials. This paper aims to systematically characterize the measurement process by comparing standard methods with the replica approach. Samples of diverse vinyl polysiloxane impression materials were cured and measured at various stages of the optical manufacturing. The goal is to optimize the process, providing a comprehensive evaluation of its advantages and effectiveness.