Abstract
The Technology Demonstration Mirror (TDM) is designed to be a 1.8 m diameter off-axis primary mirror with a highly aspheric surface. This TDM development effort was targeted at demonstrating technology relevant to the chronographic Terrestrial Planet Finder (TPF) mission. A 2D Lorentzian Power Spectral Density (PSD) function was a requirement used for specifying the mid-spatial frequency content, between 0.025 cm<sup>-1</sup> and 0.5 cm<sup>-1</sup>, of the interferometricallymeasured TDM. The objective of this study was to develop a 2D PSD algorithm with improved immunity to spatial frequency noise relative to full aperture PSD approaches. The Welch Overlapping Sub Aperture (WOSA) PSD algorithm was identified for its strong variance-reducing characteristics inherent in the averaging of multiple PSDs. Results of this study showed that the variance in the WOSA PSD is roughly an order of magnitude lower than that of the full aperture PSD. The impact of window type, low-frequency pre-filtering, and RMS scale factors on the PSD results are also considered.
Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
