Comparison of Real Foucault Images of a Telescope Mirror and Simulated Foucault from Interferometric Data

Dale Eason May 25 2006
The top row of images are the real Foucualt Images of an 8 inch F5.3 Telescope Mirror.  The second row are the simulated Foucault images created from the interferometric data of the same mirror.

real and simulated Foucault

I think they are very similar except at the edge.  The simulated images show a diffraction ring where none really exists.  I'm still working at characterizing the false artifacts that arise from my process.  Some of which are:

Below is top level view of the surface as computed by the interferometric software as compared to the best fit paraboloid.  Red is high surface, blue is low.

surface view

Below is a profile through a diameter of the mirror to help show the scale of the surface error.  The purple line is the profile computed by FigureXP using a 7 zone mask.  The adjuster in the upper right corner shows the angle of the diameter measured.  I picked this diameter because it seemed to be the closest match to the FigureXP measurements.  The vertical scale is in nanometer deviation from the perfect paraboloid.

Last here is a view with exaggerated height.  Just because I like it.  The box around it is 1/8 wave heigh.