Single point diamond turning of optical surfaces is becoming more commonly used, especially in infrared systems. However, the process introduces its own peculiar forms of figure error that can compromise performance. These errors include tool misalignment error, thermal effects, low frequency surface ripple, and mounting effects. Techniques have been developed to model these effects in Monte Carlo simulations using conventional optical design codes to predict the changes in optical performance.© (2003) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.