Mid-spatial frequency matters: examples of the control of the power spectral density and what that means to the performance of imaging systems

We will discuss mid-spatial frequency (MSF) optical surface errors, and how they affect optical performance of an optical system, including contrast, ensquared energy and pixel cross-talk. MSF errors will be represented in terms of Power Spectral Density (PSD), and examples will be discussed where PSD is well controlled and poorly controlled. We will show recent examples of PSDs of aspheric mirrors, sometimes with very challenging aspheric departure or other attributes, as routinely finished Tinsley, and suggest ways the designer can effectively specify an optic for smoothness.