Evaluating Frequency Error Property of Wavefront of Large Optics by PSD Collapse

Operation of two-dimensional Power Spectral Density (2-D PSD) of large optics wavefront is briefly described and PSD collapse is introduced to evaluate the intermediate frequency error property of wavefront. As PSD collapse is Radon transform projection of 2-D Power Spectral Density at any angle, all valid data of wavefront of optics are used in calculation of the PSD collapse and the features of 1-D PSD were inherited in PSD collapse. Although PSD collapse is as same as 1-D PSD in unit and behavior style, it is better for evaluating intermediate frequency error property of optics wavefront than 1-D PSD or 2-D PSD. As PSD collapse calculation uses all valid data of evaluated optics wave front and can be directly perceived through its profile, the PSD collapse may possibly be the standard evaluating method of PSD.