Optics
Diagram of Tilt/Focus Box(Looking From Below, Towards Telescope)
Focus sweep montage, knife edge and Hartmann mask tests, Sept 5
Focus sweep montage and Hartmann mask sweep, Sept 7
Focus sweep with the SBIG, Sept 8
Focus sweep with the SBIG and the old secondary, Sept 10
Focus Sweeps from September 14, 2010 (with PreCam)
Focus Sweeps from Sept 16, 2010 (with PreCam)
Focus Sweeps from Sept 17, 2010 (with PreCam)
Focus Sweeps from Sept 18, 2010 (with PreCam)
Focus Sweeps from Sept 19, 2010 (with PreCam)
Focus Sweeps from Sept 20, 2010 (with PreCam)
Focus Sweeps from Sept 21, 2010 (with PreCam)
Comparison one file (Note under construction)
Steve Kent:
Here is an attempt to reproduce the focus sweep that was taken on Sept. 7. The left half of the picture has spot diagrams from my raytrace program, while the images on the right are from the "optic-sept-7" web page. I made a guess at the telescope design (61 cm clear aperture, f/3.5). For simplicity, I insert a folding flat that is perpendicular to the optical axis rather than tilted at 45 deg.
On the flat (which I assume has a radius of 21 cm), I introduce two zernike terms to represent astigmatism and coma. The astigmatic term has a semi-amplitude of 100 microns at the mirror edge. The comatic term has a semi-amplitude of 54 microns and the axis is rotated by 22 degrees relative to that of the astigmatic term. Focus steps are 500 microns, with each step moving the focal plane away from the folding flat.
I did NOT fine-tune any of the Zernike parameters - they were coarse guesses that seemed to work.
Aside from an overall rotation of the pattern, I match the bottom half of the foccus sweep reasonably well. The top half doesn't match as well - I'm not sure what needs to be added to improve it.
I note that since the beam does not fill the entire folding flat, the wavefront errors themselves are not as large - smaller aberrations would be needed if the problem were the primary mirror itself.
(Click for bigger version)
Picture of straight edge on secondary and secondary in box.
Pictures of the RTV which mounts the secondary to the secondary support: one and two.