Evaluating intermediate frequency error property of wavefront of optical components with PSD collapse

Arithmetic of two-dimensional power spectral density (2-D PSD) of large optics wavefront was briefly described and PSD collapse was introduced to evaluate the intermediate frequency error property of wavefront. As the PSD collapse is radon transform projection of 2-D power spectral density at any angle, all valid data of wavefront of optics were used in calculation of the PSD collapse and the features of 1-D PSD were inherited in PSD collapse. Although the PSD collapse is the same as 1-D PSD in unit and behaving style, it is better in 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 wavefront and can be directly perceived through its profile, the PSD collapse is possibly the sta